JP2017125429A - Two-stage turbocharger system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-stage turbocharger system capable of improving the mountability thereof in a vehicle and reducing facility cost.SOLUTION: A two-stage turbocharger system equipped with a high pressure stage turbocharger 6 and a low pressure stage turbocharger 10 comprises: a bypass pipe 7 that bypasses a high pressure stage turbine 3 by short-cutting the inlet side and the outlet side of the high pressure stage turbine 3; and a three-way valve 20 disposed at a place where the bypass pipe 7 is joined to the outlet side of the high pressure stage turbine 3. The three-way valve 20 is configured in such a manner that a normal position to shut off only the bypass pipe 7, a high pressure stage bypass position to throttle only the bypass pipe 7 into a necessary opening in a state where at least a part of the bypass pipe 7 is opened, an exhaust throttle position to throttle the outlet side of the high pressure stage turbine 3 into a necessary opening while maintaining the bypass pipe 7 in a shut-off state, and an exhaust brake position to shut off only the inlet side of a low pressure stage turbine 8 can be selectively switched.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a two-stage supercharging system.

  In recent years, in order to realize downsizing and torque increase of a supercharging system, a two-stage supercharging system employing a small-sized high-pressure turbocharger has been studied. In this type of two-stage supercharging system, FIG. As shown in FIG. 2, the high-pressure stage turbocharger 6 operates the high-pressure stage turbine 3 by the exhaust G sent from the exhaust manifold 2 of the engine 1 and supplies the intake air A compressed by the high-pressure stage compressor 4 to the intake manifold 5 of the engine 1. A low-pressure stage turbo that operates the low-pressure stage turbine 8 with the exhaust G sent from the high-pressure stage turbine 3 of the high-pressure stage turbocharger 6 and supplies the intake air A compressed by the low-pressure stage compressor 9 to the high-pressure stage compressor 4 Charger 10 is provided.

  Furthermore, an intercooler 12 is interposed between the outlet side of the low-pressure stage compressor 9 of the low-pressure stage turbocharger 10 and the inlet side of the high-pressure stage compressor 4 of the high-pressure stage turbocharger 6, and the high-pressure stage compressor An aftercooler 13 is interposed between the outlet side of 4 and the intake manifold 5 of the engine 1.

  An EGR pipe 14 is provided from the upstream side of the high-pressure turbine 3 in the exhaust system (specifically, the exhaust manifold 2) to the downstream side of the aftercooler 13 (specifically, the intake manifold 5). 14 is provided with an EGR cooler 15 that cools the exhaust gas G diverted from the exhaust system, and an EGR valve 16 that adjusts the flow rate of the exhaust gas G to be recirculated to the intake system.

  Thus, in such a two-stage supercharging system, when the engine 1 is in operation, the exhaust G sent from the exhaust manifold 2 flows into the high-pressure turbine 3 and drives the high-pressure compressor 4. The intake air A that flows into the low-pressure turbine 8 and drives the low-pressure compressor 9 and flows into the low-pressure compressor 9 and is compressed is supplied to the high-pressure compressor 4 through the intercooler 12, and the high-pressure compressor 4 is compressed again and supplied to the intake manifold 5 via the aftercooler 13. Therefore, if the amount of intake A supplied to the cylinder is increased and the fuel injection amount per cycle is increased, the output of the engine 1 is increased. Can be increased.

  Further, a part of the exhaust G flows from the exhaust manifold 2 into the EGR pipe 14, and the exhaust G cooled by the EGR cooler 15 and adjusted in flow rate by the EGR valve 16 is combined with the intake air A with the intake manifold 5. This reduces the combustion temperature in the cylinder and reduces the generation of NOx.

  However, in the high-speed and high-load region where the flow rate of the exhaust G is large (the operation region indicated by cross-hatching in the graph of FIG. 7), the small-sized high-pressure turbocharger 6 rotates excessively and the supercharging pressure is more than necessary. The maximum in-cylinder pressure of each cylinder of the engine 1 exceeds the limit value, and the engine cannot be operated, or the supercharging pressure becomes higher than the pressure of the exhaust manifold 2 and the exhaust G cannot be recirculated. There is.

  Therefore, a bypass pipe 7 that bypasses the high-pressure turbine 3 is provided, and a bypass valve 11 is provided in the middle of the bypass pipe 7, and the bypass valve 11 is opened in a high-speed and high-load region so that only the exhaust gas G having an appropriate flow rate is high pressure. It flows through the stage turbine 3, and the remainder is bypassed to the high pressure stage turbine 3 and led to the low pressure stage turbine 8.

  Here, in the operation region indicated by cross hatching in the graph of FIG. 7, the operation of fully opening the bypass valve 11 is performed, but in the operation region indicated by hatching, the bypass valve 11 is appropriately opened. By narrowing the degree, an operation for adjusting the flow rate ratio of the exhaust G that bypasses the high-pressure turbine 3 is performed.

  Further, as the exhaust G bypasses the high-pressure stage turbine 3 and the rotational speed of the high-pressure stage compressor 4 is reduced and the flow of the intake air A is delayed, the outlet side of the low-pressure stage compressor 9 to the outlet side of the high-pressure stage compressor 4 The flow is distributed to the intake air switching pipe 17, and the intake air switching pipe 17 is provided with a check valve 18 that prevents the reverse flow of the intake air A.

  In addition, as prior art document information related to the two-stage supercharging system as described above, the following Patent Document 1 by the same applicant as the present invention already exists.

JP 2012-77730 A

  However, in such a two-stage turbocharging system, the exhaust throttle valve 19 is throttled when the differential pressure required for recirculation of the exhaust G (differential pressure between the exhaust manifold 2 side and the intake manifold 5 side) cannot be obtained. There is a type that assists in recirculation of the exhaust G, and this type of exhaust throttle valve 19 is also used as a substitute for a single exhaust valve that also serves as an exhaust brake. 11 and at least two exhaust valves are required for the exhaust system (when exhaust brakes are separately provided, three exhaust valves are required), so a large space is required for these exhaust valves and their drive mechanisms. As a result, there is a problem that the mountability to the vehicle becomes worse, and the expensive equipment with adjustable opening is required for these exhaust valves. There is also a problem that lead.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a two-stage supercharging system that can be mounted on a vehicle and can reduce equipment costs.

  The present invention relates to a high-pressure stage turbocharger that operates a high-pressure stage turbine by exhaust gas delivered from an engine and supplies intake air compressed by a high-pressure stage compressor to the engine, and the high-pressure stage turbine of the high-pressure stage turbocharger. A two-stage supercharging system comprising a low-pressure stage turbocharger that operates a low-pressure stage turbine by exhaust gas and supplies intake air compressed by a low-pressure stage compressor to a high-pressure stage compressor. A bypass pipe that bypasses the high-pressure turbine by bypassing the high-pressure turbine, a three-way valve at the junction of the bypass pipe to the outlet side of the high-pressure turbine, a normal position that blocks only the bypass pipe, and a bypass pipe The high-pressure stage bypass position and the bypass piping to reduce the required opening with at least a part of The three-way valve can be selectively switched between an exhaust throttle position that restricts the required opening on the outlet side of the high-pressure stage turbine while maintaining the disconnected state, and an exhaust brake position that shuts off only the inlet side of the low-pressure stage turbine. It is characterized by comprising.

  Thus, during normal operation, if the three-way valve is in the normal position and only the bypass pipe is shut off, the outlet side of the high-pressure stage turbine is opened to the inlet side of the low-pressure stage turbine to perform normal two-stage supercharging. In an operating range where the supercharging pressure is higher than necessary, if the three-way valve is a high-pressure stage bypass position and only the bypass pipe is opened to at least a part of the opening, the bypass pipe is opened. As a result, only the exhaust gas having an appropriate flow rate is allowed to flow through the high-pressure stage turbine, and the rest can be led to the low-pressure stage turbine by bypassing the high-pressure stage turbine.

  Furthermore, if the differential pressure required for exhaust gas recirculation cannot be obtained, the exhaust pressure can be reduced by reducing the outlet side of the high-pressure turbine to the required opening while keeping the bypass piping shut off with the three-way valve set to the exhaust throttle position. By increasing the resistance, the pressure of the exhaust manifold is increased, and a differential pressure necessary for exhaust gas recirculation can be easily obtained. If exhaust throttling is performed in this manner, exhaust can continue to flow through the high-pressure turbine and the rotation of the high-pressure turbine can be continued, and a reduction in engine output can be suppressed.

  Also, if you want to apply the exhaust brake, if the three-way valve is in the exhaust brake position and only the inlet side of the low-pressure turbine is shut off, the exhaust will not flow into the high-pressure turbine or the low-pressure turbine, and pumping on the engine side Loss will increase and engine braking will be greatly enhanced.

  In other words, the three functions of the bypass valve, the exhaust throttle valve, and the exhaust brake are integrated by selectively switching to the normal position, the high-pressure stage bypass position, the exhaust throttle position, and the exhaust brake position and using the three-way valve. It is possible to cover with three three-way valves, and it becomes unnecessary to provide two or more expensive exhaust valves in the exhaust system as in the prior art.

  Furthermore, in more concretely carrying out the present invention, the first port toward the bypass pipe out of the three ports of the three-way valve and the second port toward the inlet side of the low-pressure turbine are arranged to face each other. A third port heading toward the exit side of the high-pressure turbine in a direction perpendicular to the direction is disposed, and a valve body is provided that is rotatable in a circumferential direction in which the first port, the second port, and the third port are continuous, It is preferable to define a closed range by the valve body so that the third port can be throttled to the required opening while the shut-off state of the first port is maintained at the exhaust throttle position.

  According to the two-stage supercharging system of the present invention, the three functions of the bypass valve, the exhaust throttle valve, and the exhaust brake can be provided by one three-way valve, and the exhaust valves necessary for the exhaust system are integrated into one three-way valve. Therefore, it is possible to achieve a significant effect that the space can be saved significantly, the mounting property to the vehicle can be improved, and the facility cost can be greatly reduced.

It is a systematic diagram which shows an example of the form which implements this invention. It is explanatory drawing regarding the normal position of the three-way valve of FIG. It is explanatory drawing regarding the high pressure stage bypass position of the three-way valve of FIG. It is explanatory drawing regarding the exhaust throttle position of the three-way valve of FIG. It is explanatory drawing regarding the exhaust-brake position of the three-way valve of FIG. It is a systematic diagram which shows an example of the conventional two-stage supercharging system. It is a graph explaining the operation area | region which wants to detour a high pressure stage turbine.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 5 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIG. 6 represent the same items.

  That is, in the two-stage turbocharging system shown in FIG. 1, the high-pressure turbine 3 is driven by the exhaust G sent from the engine 1 in substantially the same manner as the conventional two-stage turbocharging system described above with reference to FIG. 6. The high-pressure stage turbocharger 6 that feeds the intake air A that is operated and compressed by the high-pressure stage compressor 4 to the engine 1 and the low-pressure stage turbine 8 is operated by the exhaust G that is sent from the high-pressure stage turbine 3 of the high-pressure stage turbocharger 6. And a low-pressure turbocharger 10 for supplying the intake air A compressed by the low-pressure compressor 9 to the high-pressure compressor 4.

  However, a bypass pipe 7 that bypasses the high-pressure stage turbine 3 by short-circuiting the inlet side and the outlet side of the high-pressure stage turbine 3 is provided, and three-way is provided at the junction of the bypass pipe 7 to the outlet side of the high-pressure stage turbine 3. A normal position (see FIG. 2) that includes the valve 20 and shuts off only the bypass pipe 7, and a high-pressure stage bypass position (see FIG. 3) that restricts only the bypass pipe 7 to a required opening with at least a part opened. An exhaust throttle position (see FIG. 4) that restricts the opening of the high-pressure turbine 3 to the required opening degree while holding the bypass pipe 7 in a shut-off state, and an exhaust brake position that shuts off only the inlet side of the low-pressure turbine 8 (see FIG. 4). The three-way valve 20 is configured so that it can be selectively switched.

  That is, as a specific configuration of the three-way valve 20, a first port 21 that faces the bypass pipe 7 out of the three ports and a second port 22 that faces the inlet side of the low-pressure turbine 8 are arranged opposite to each other. A third port 23 directed to the exit side of the high-pressure turbine 3 is disposed in a direction perpendicular to the facing direction, and the first port 21, the second port 22, and the third port 23 are rotatable in a circumferential direction. Is provided with a valve body 24, and the closed range of the valve body 24 is defined so that the third port 23 can be throttled to the required opening while maintaining the shut-off state of the first port 21 at the exhaust throttle position. Yes.

  Thus, as shown in FIG. 2, during normal operation, if the three-way valve 20 is in the normal position and only the bypass pipe 7 is shut off, the outlet side of the high-pressure turbine 3 is opened to the inlet side of the low-pressure turbine 8. It is possible to perform normal two-stage supercharging. Further, as shown in FIG. 3, in an operation region where the supercharging pressure is higher than necessary, the three-way valve 20 is used as a high-pressure stage bypass position and at least one bypass pipe 7 is provided. If the opening is reduced to the required opening degree, the bypass pipe 7 is opened, and only the exhaust gas G having an appropriate flow rate flows into the high-pressure turbine 3, and the rest bypasses the high-pressure turbine 3 and the low-pressure turbine 8. It becomes possible to lead to.

  Further, as shown in FIG. 4, when the differential pressure required for recirculation of the exhaust G cannot be obtained, the outlet side of the high-pressure turbine 3 is maintained with the three-way valve 20 set to the exhaust throttle position and the bypass pipe 7 kept in the shut-off state. If only the required opening is reduced, the exhaust resistance is increased, the pressure of the exhaust manifold 2 is increased, and the differential pressure necessary for the recirculation of the exhaust G is easily obtained. If the exhaust throttling is performed in this manner, the exhaust G can be continuously supplied to the high-pressure turbine 3 and the rotation of the high-pressure turbine 3 can be continued, so that a decrease in engine output can be suppressed.

  Further, as shown in FIG. 5, when it is desired to apply the exhaust brake, both the high-pressure turbine 3 and the low-pressure turbine 8 can be operated by shutting off only the inlet side of the low-pressure turbine 8 by setting the three-way valve 20 to the exhaust brake position. Exhaust G stops flowing, pumping loss on the engine 1 side increases, and engine braking is greatly enhanced.

  That is, by selectively switching to the normal position, the high-pressure stage bypass position, the exhaust throttle position, and the exhaust brake position and using the three-way valve 20, the three functions of the bypass valve, the exhaust throttle valve, and the exhaust brake can be achieved. One three-way valve 20 can cover this, and it is not necessary to provide two or more expensive exhaust valves in the exhaust system as in the prior art.

  Therefore, according to the above embodiment, the three functions of the bypass valve, the exhaust throttle valve, and the exhaust brake can be provided by the single three-way valve 20, and the exhaust valves necessary for the exhaust system are integrated into the single three-way valve 20. As a result, it is possible to achieve a significant space saving, to improve the mounting property on the vehicle, and to greatly reduce the equipment cost.

  It should be noted that the two-stage supercharging system of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

1 Engine 3 High-pressure turbine 4 High-pressure compressor 6 High-pressure turbocharger 7 Bypass piping 8 Low-pressure turbine 9 Low-pressure compressor 10 Low-pressure turbocharger 20 Three-way valve 21 First port 22 Second port 23 Third port 24 Valve body A Intake G Exhaust

Claims (2)

  A high-pressure stage turbocharger that operates a high-pressure stage turbine by exhaust gas sent from the engine and supplies intake air compressed by a high-pressure stage compressor to the engine, and a low-pressure stage by exhaust gas sent from the high-pressure stage turbine of the high-pressure stage turbocharger A two-stage supercharging system comprising a low-pressure turbocharger that operates a turbine and feeds intake air compressed by a low-pressure compressor to a high-pressure compressor, and shorts the inlet side and the outlet side of the high-pressure turbine. A bypass pipe that bypasses the high-pressure stage turbine, and a three-way valve is provided at the junction of the bypass pipe to the outlet side of the high-pressure turbine, so that at least one of the normal position that blocks only the bypass pipe and at least one bypass pipe is provided. High-pressure stage bypass position that restricts the opening to the required opening level with the opening open, and the bypass piping in the shut-off state The three-way valve is configured so that it can selectively switch between an exhaust throttle position that restricts the required opening on the outlet side of the high-pressure turbine while holding it, and an exhaust brake position that shuts off only the inlet side of the low-pressure turbine A two-stage turbocharging system characterized by   Out of the three ports of the three-way valve, the first port facing the bypass piping and the second port facing the inlet side of the low-pressure turbine are arranged opposite to each other, and at the outlet side of the high-pressure turbine in a direction perpendicular to the facing direction. A third port is provided, and a valve body is provided that is rotatable in the circumferential direction in which the first port, the second port, and the third port are continuous, and the shut-off state of the first port is maintained at the exhaust throttle position. However, the two-stage supercharging system according to claim 1, wherein a closed range by the valve body is defined so that the third port can be narrowed to a required opening degree.

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