JP2010196540A - Supercharging system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharging system for an internal combustion engine cooling a compressor without deteriorating fuel economy. <P>SOLUTION: In this supercharging system for the internal combustion engine, a turbosupercharger 10 is provided for recovering exhaust energy by a turbine 12 in an exhaust passage 4 and driving the compressor 11 in an intake passage 3. The supercharging system includes: a cooling passage 21 provided in a compressor housing 13, and having one end 21a closed and the other end 21b opened; a piston 23 reciprocatably inserted into the other end 21b of the cooling passage 21; a stack 22 arranged in the cooling passage 21 so that when a standing wave of a one-quarter wavelength is generated in the cooling passage 21, one end 22a is positioned on the side of the loop of the standing wave and also the other end 22b is positioned on the side of the node of the standing wave, and internally having a plurality of spaces communicating with the cooling passage 21; a cooling fin 24 cooling the one end 22a of the stack 22; and a connection passage 25 connecting the intake passage 3 to the other end 21b of the cooling passage 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a supercharging system for an internal combustion engine that includes a turbocharger that compresses intake air with a compressor provided in an intake passage of the internal combustion engine, thereby supercharging the internal combustion engine.

  There is known a turbocharger that recovers exhaust energy by a turbine in an exhaust passage, drives a compressor in an intake passage, and compresses intake air by the compressor to supercharge an internal combustion engine. In such a turbocharger, heat is generated when the intake air is compressed by the compressor. Therefore, if oil mist adheres in the compressor housing, the oil mist may be carbonized and the inside of the housing may be caulked. In particular, since the flow path of the diffuser portion of the compressor is narrow, when the diffuser portion is caulked, intake air hardly flows and the efficiency of the compressor decreases. Therefore, a supercharger is known in which a cooling path is provided in a portion adjacent to a seal plate constituting a part of the diffuser portion of the compressor, and the cooling water is supplied to the cooling path to cool the compressor (see Patent Document 1). . In addition, as a prior art related to the present invention, there is an internal combustion engine in which a thermoacoustic heat transfer device is provided in an exhaust passage so as to control the temperature of exhaust gas introduced into a catalytic converter (see Patent Document 2).

JP 2004-44451 A JP 2007-155167 A

  When the compressor housing is cooled with cooling water as in the supercharger of Patent Document 1, the amount of cooling water to be circulated increases in the internal combustion engine provided with the supercharger. Therefore, there exists a possibility that a water pump and a radiator may enlarge. Further, when the water pump is increased in size, energy consumed for driving the pump increases, so that fuel consumption may be deteriorated.

  Therefore, an object of the present invention is to provide a supercharging system for an internal combustion engine that can cool a compressor without deteriorating fuel consumption.

  The supercharging system for an internal combustion engine of the present invention includes a turbocharger that recovers exhaust energy by a turbine provided in an exhaust passage of the internal combustion engine and drives a compressor provided in the intake passage of the internal combustion engine. In the internal combustion engine supercharging system, a cooling passage provided in the compressor housing, having one end closed and the other end opened, and a piston member inserted reciprocally into the other end of the cooling passage; When a 1/4 wave standing wave is generated in the cooling passage, one end is located on the antinode side of the standing wave and the other end is located on the node side of the standing wave. A stack having a plurality of spaces disposed in the cooling passage and communicating with the cooling passage, cooling means for cooling the one end of the stack, and the intake passage or the exhaust passage Includes a connecting passage connecting either the one passage and the other end of the cooling passage, the (claim 1).

  As is well known, pressure pulsations with a frequency corresponding to the rotational speed of the internal combustion engine are generated in the intake passage and the exhaust passage of the internal combustion engine. In the supercharging system of the present invention, since the other end of the cooling passage is connected to the intake passage or the exhaust passage, the piston member can be vibrated by the pulsation of this pressure. When the piston member vibrates, a wave traveling from the other end to one end is continuously generated in the cooling passage. These waves are reflected at one end and travel from one end to the other. Then, when these waves whose traveling directions are opposite to each other resonate, a standing wave (also called a standing wave) is generated in the cooling passage. In this case, the pressure largely fluctuates in the antinode portion of the standing wave, and the pressure hardly fluctuates in the node portion of the standing wave. Since one end of the stack is located on the ventral side of the standing wave and the other end is located on the node side, the gas in the internal space is cooled in response to pressure fluctuations in the antinode of the standing wave. It reciprocates in the stack along the passage. When the gas moves to the far side of the standing wave, it is compressed and the temperature rises, but a part of the heat is dissipated to the stack, so the temperature drops slightly. On the other hand, when the gas moves to the node side of the standing wave, it adiabatically expands, thereby lowering the temperature of the gas. And by repeating such movement, compression and expansion of the gas, heat can be transferred from the other end of the stack to one end. That is, according to the supercharging system of the present invention, heat can be transferred from the other end of the stack to one end by a thermoacoustic phenomenon. Since one end of the stack is cooled by the cooling means, heat can be released to the outside. As described above, according to the supercharging system of the present invention, heat can be transferred from the other end of the stack to one end, and therefore, a portion of the cooling passage between the other end of the cooling passage and the stack. Heat can be dissipated to the outside. This thermoacoustic phenomenon is generated by vibrating the piston member by the pressure pulsation in the intake passage or the exhaust passage. Therefore, the compressor can be cooled without deteriorating fuel consumption.

  In one form of the supercharging system for an internal combustion engine of the present invention, the cooling passage may be provided in a seal plate that is a part of the diffuser portion so as to be adjacent to the diffuser portion of the housing. ). Generally, in the housing, the flow rate of the intake air becomes narrow at the diffuser portion. Therefore, when coking occurs in the diffuser portion, the efficiency of the compressor is greatly reduced. In this embodiment, since the cooling passage is provided so as to be adjacent to the diffuser portion, coking at the diffuser portion can be suppressed.

In one form of the supercharging system of the internal combustion engine of the present invention, the internal combustion engine is configured as a four-cycle internal combustion engine having a plurality of cylinders, and the length of the cooling passage is L, When the number of cylinders of the internal combustion engine is C, the speed of sound is V, and the number of revolutions per minute of the internal combustion engine in an operating state where the temperature of the intake air at the outlet of the compressor is highest is N, V / N × C / 60/2) / 4
May be set to satisfy (Claim 3). In this case, a ¼ wavelength standing wave can be generated in the cooling passage in an operating state in which the temperature of the intake air at the outlet of the compressor requiring cooling of the compressor is the highest. Therefore, the compressor can be appropriately cooled.

  In one form of the supercharging system of the internal combustion engine of the present invention, the connection switching valve that opens and closes the connection passage, and the connection switching valve is opened in an operation state in which the temperature of the intake air at the outlet of the compressor becomes the highest. And a control means for controlling the connection switching valve. In this case, the compressor can be cooled or the cooling can be stopped by opening and closing the connection switching valve. In addition, since the control means opens the connection switching valve in the operation state in which the temperature of the intake air at the outlet of the compressor becomes the highest, it is possible to cool the compressor appropriately.

  In one form of the supercharging system for an internal combustion engine of the present invention, the cooling means may be a plurality of cooling fins provided outside the housing. In this case, the heat of the stack can be dissipated into the air.

  As described above, according to the supercharging system for an internal combustion engine of the present invention, a thermoacoustic phenomenon is generated in the cooling passage by utilizing the pulsation of the pressure generated in the intake passage or the exhaust passage. The heat of the compressor can be dissipated outside by an acoustic phenomenon. Therefore, the compressor can be cooled without deteriorating fuel consumption.

The figure which shows the outline of the internal combustion engine in which the supercharging system which concerns on one form of this invention was integrated. The figure which expands and shows a part inside compressor. The figure which shows the compressor seen from the arrow III direction of FIG. The figure for demonstrating the thermoacoustic phenomenon generate | occur | produced in a cooling channel. The figure which shows the characteristic curve of the compressor of a turbocharger, and the operating line of an engine. The flowchart which shows the cooling device control routine which ECU performs. The figure which shows the modification of the supercharging system of this invention.

  FIG. 1 schematically shows an internal combustion engine in which a supercharging system according to one embodiment of the present invention is incorporated. An internal combustion engine (hereinafter sometimes referred to as an engine) 1 shown in FIG. 1 is a four-cycle internal combustion engine mounted as a driving power source in a vehicle, and has an engine body having a plurality of cylinders (not shown). 2 and an intake passage 3 and an exhaust passage 4 connected to each cylinder of the engine body 2. The intake passage 3 is connected to each cylinder via an intake manifold (hereinafter also referred to as intake manifold) 3a forming a part thereof. The exhaust passage 4 is connected to each cylinder via an exhaust manifold (hereinafter sometimes referred to as an exhaust manifold) 4a forming a part thereof. The intake passage 3 is provided with a compressor 11 of the turbocharger 10, an intercooler 5 for cooling the intake air, and a throttle valve 6 for adjusting the intake air amount. A turbine 12 of the turbocharger 10 is provided in the exhaust passage 4.

  FIG. 2 shows an enlarged part of the inside of the compressor 11. As shown in FIG. 2, the compressor 11 includes a compressor housing 13 and a compressor wheel 15 provided in the compressor housing 13 and rotating integrally with the rotary shaft 14. The compressor wheel 15 is provided with a plurality of blades 15a (only one is shown in FIG. 2). A turbine wheel (not shown) of the turbine 12 is attached to the other end of the rotating shaft 14 so as to rotate integrally. Therefore, when this turbine wheel is rotationally driven by exhaust, the compressor wheel 15 is rotationally driven by this. The compressor housing 13 is provided on the outer periphery of the wheel chamber 16 in which the compressor wheel 15 is disposed, on the outer periphery of the wheel chamber 16, and on the outer periphery of the diffuser portion 17. 17 is provided with a scroll chamber 18 communicating with 17. As shown in FIG. 2, a part of the diffuser portion 17 is configured by a seal plate 19. Since these may be the same as the known turbocharger compressor provided in the internal combustion engine, detailed description thereof is omitted.

  The compressor 11 is provided with a cooling device 20. As shown in FIG. 2, the cooling device 20 includes a plurality of cooling passages 21 (only one is shown in FIG. 2). Each cooling passage 21 is provided in the seal plate 19 so as to be adjacent to the diffuser portion 17. One end 21 a of the cooling passage 21 is disposed on the outer peripheral side of the compressor housing 13 and is closed. Further, the one end 21 a protrudes from the compressor housing 13 so as to be disposed radially outside the scroll chamber 18. On the other hand, the other end 21 b of the cooling passage 21 is disposed on the inner peripheral side of the compressor housing 13. The other end 21b is open. FIG. 3 shows a part of the compressor 11 viewed from the direction of arrow III in FIG. As shown in this figure, the cooling passage 21 extends from the inner peripheral side of the compressor housing 13 to the outer peripheral side while being curved. The length L of the cooling passage 21 (see FIG. 4) includes 1 of the engine 1 in an operating state in which the number of cylinders C of the engine 1, the speed of sound V (m / sec), and the temperature of the intake air at the outlet of the compressor 11 are highest. A value calculated by substituting the number of revolutions per minute N (rpm) into the following equation (1) is set.

        L = (V / N × C / 60/2) / 4 (1)

  As shown in FIG. 2, a stack 22 and a piston 23 as a piston member are provided in the cooling passage 21. The stack 22 is a heat exchanger, and a plurality of spaces (not shown) communicating with the outside are provided in the stack 22. As the stack 22, for example, a stack of many stainless steel plates with a small gap is provided. A ceramic filter having a plurality of minute holes may be provided as the stack 22. The stack 22 is disposed in the cooling passage 21 so as to be closer to the one end 21a than the middle between the one end 21a and the other end 21b, and to provide a predetermined gap between the one end 21a. Further, the stack 22 is disposed in the cooling passage 21 so as to be positioned radially outside the diffuser portion 17 of the compressor 11. The piston 23 is inserted into the other end 21b of the cooling passage 21 so as to be able to reciprocate. The seal plate 19 is provided with a plurality of cooling fins 24 as cooling means protruding toward the turbine 12 side. The plurality of cooling fins 24 are provided concentrically as shown in FIG. Further, as shown in FIG. 2, the plurality of cooling fins 24 are arranged so that the end portion of the stack 22 arranged on the one end side 21a, that is, the end portion 22a on the outer peripheral side of the stack 22 is cooled. It is arranged around. As shown in FIG. 1, the other end 21 b of the cooling passage 21 is connected to the intake manifold 3 a by a connection passage 25. The connection passage 25 is provided with a connection switching valve 26 that opens and closes the passage 25.

  Next, a method for cooling the compressor 11 by the cooling device 20 will be described with reference to FIG. The cooling device 20 cools the compressor 11 using a thermoacoustic phenomenon. As is well known, in the intake passage 3 of the engine 1, pressure pulsation (hereinafter referred to as intake pulsation) having a frequency corresponding to the rotational speed of the engine 1 is generated. Therefore, when the connection switching valve 26 is opened and the other end 21b of the cooling passage 21 and the intake manifold 3a are connected, the piston 23 vibrates due to the intake pulsation of the intake manifold 3a. When the piston 23 vibrates in this way, a wave W1 traveling from the other end 21b to the one end 21a side is continuously generated in the cooling passage 21. This wave W1 is reflected at one end 21a in the cooling passage 21 and becomes a wave W2 directed toward the other end 21b. The length L of the cooling passage 21 is set based on the number of revolutions N per minute of the engine 1 in the operation state in which the temperature of the intake air at the outlet of the compressor 11 is highest as described above. For this reason, when the connection switching valve 26 is opened while the engine 1 is operating at this rotational speed N, the waves W1 and W2 overlap and resonate, whereby a standing wave (1/4 wavelength in the cooling passage 21 ( Also called standing waves). At this time, an antinode of a standing wave is generated at one end 21 a of the cooling passage 21, and a node of a standing wave is generated at the other end 21 b of the cooling passage 21. Therefore, the end 22a on the outer peripheral side of the stack 22 is positioned on the antinode side of the standing wave, and the end 22b on the inner peripheral side is positioned on the node side of the standing wave. Therefore, the end 22a on the outer peripheral side of the stack 22 corresponds to one end of the stack of the present invention, and the end 22b on the inner peripheral side corresponds to the other end of the stack of the present invention.

  Then, by generating such a ¼ wavelength standing wave in the cooling passage 21, the temperature of the end 22 b on the inner peripheral side of the stack 22 is lowered by the thermoacoustic phenomenon, and the outer peripheral side of the stack 22. The temperature of the end portion 22a can be increased. This is because the gas is repeatedly compressed and expanded while moving along the cooling passage 21 in the stack 22 by the standing wave. Specifically, in the stack 22, the gas is first moved slightly by the standing wave to the outer peripheral side (the left side in FIG. 4) where the pressure is high and compressed, thereby reducing the volume. At this time, the temperature rises due to adiabatic compression, but since the heat is radiated to the wall surface of the stack 22 existing near the gas, the temperature of the gas slightly decreases. Next, this gas is slightly moved to the inner peripheral side (right side in FIG. 4) by the standing wave. At this time, the gas adiabatically expands and the temperature decreases. As described above, since the gas dissipates heat at the position when it moves to the outer peripheral side, the temperature becomes lower than the surroundings by the amount that the temperature is reduced by the heat dissipation. Thereafter, the gas is slightly moved to the outer peripheral side by the standing wave again and compressed. Thus, the compression and expansion of the gas are repeatedly performed by the standing wave. Since such gas compression and expansion is performed in each part in the stack 22, the heat moves along the cooling passage 21 to the outer peripheral side. Therefore, the temperature of the end 22b on the inner peripheral side of the stack 22 can be lowered, and the temperature of the end 22a on the outer peripheral side of the stack 22 can be increased. As a result, the temperature of the portion of the cooling passage 21 on the inner peripheral side of the stack 22 can be lowered to cool the seal plate 19. On the other hand, the heat that has moved to the outer peripheral side of the stack 22 in the cooling passage 21 is dissipated into the air by the plurality of cooling fins 24.

  The operation of the connection switching valve 26 of the cooling device 20 is controlled by an engine control unit (ECU) 30. The ECU 30 is configured as a computer including a microprocessor and peripheral devices such as RAM and ROM necessary for its operation, and controls the operating state of the engine 1 based on signals output from various sensors provided in the engine 1. It is a well-known computer unit. The ECU 30 may be referred to as an air flow meter 31 that outputs a signal corresponding to the intake air amount as a sensor for detecting the operating state of the engine 1 and the opening of the throttle valve 6 (hereinafter, abbreviated as the throttle opening). ) Is connected to a throttle opening sensor 32 or the like that outputs a signal corresponding to. In addition to this, various sensors are connected to the ECU 30, but their illustration is omitted.

  FIG. 5 shows a characteristic curve of the compressor 11 of the turbocharger 10 and an operation line of the compressor 11 when the engine 1 is operated at full load. Solid lines L1 and L2 indicate the surge lines of the compressor 11. A broken line L3 indicates an operating line of the compressor 11 when the engine 1 is operated at full load, that is, the throttle 6 is fully opened. The pressure ratio in FIG. 5 is a value obtained by dividing the pressure of the intake air at the outlet of the compressor 11 by the pressure of the intake air at the inlet of the compressor 11. As indicated by the broken line L3, in the engine 1, the pressure ratio of the compressor 11 increases as the intake air amount increases. When the intake air amount exceeds a predetermined amount, the pressure ratio of the compressor 11 decreases. The temperature of the intake air at the outlet of the compressor 11 is highest in the operation region where the pressure ratio changes from increase to decrease, that is, the operation region A in FIG. In the operation region A, the compressor 11 has a high pressure ratio and low efficiency. Therefore, the ECU 30 controls the operation of the connection switching valve 26 of the cooling device 20 so that the compressor 11 is cooled when the operating state of the engine 1 is within the operating region A. FIG. 6 shows a cooling device control routine that the ECU 30 repeatedly executes at a predetermined cycle during operation of the engine 1 in order to control the operation of the connection switching valve 26. By executing this control routine, the ECU 30 functions as the control means of the present invention.

  In the control routine of FIG. 6, the ECU 30 first acquires the operating state of the engine 1 in step S11. As the operating state of the engine 1, for example, an intake air amount, a throttle opening degree, and the like are acquired. In the next step S12, the ECU 30 determines whether or not the intake air amount is greater than or equal to a predetermined determination air amount set in advance. The predetermined determination air amount is set as a determination criterion for determining whether or not the operation state of the compressor 11 is within the operation region A shown in FIG. For example, the air amount Q in FIG. 5 is set as the determination air amount.

  If it is determined that the intake air amount is greater than or equal to the determination air amount, the process proceeds to step S13, where the ECU 30 determines whether or not the throttle opening is equal to or greater than a predetermined determination opening. This determination opening is also set as a determination criterion for determining whether or not the operation state of the engine 1 is in the operation region A shown in FIG. As described above, the broken line L3 in FIG. 5 is an operation line of the compressor 11 when the throttle opening is at a full load and is operated. Therefore, it is possible to determine whether or not the current pressure ratio is a pressure ratio corresponding to the operation region A by determining the ratio of the current throttle opening to the fully open position. Therefore, as the determination opening, for example, a lower limit value of a throttle opening range in which the pressure ratio is within the operation region A is set. That is, in these steps S12 and S13, it is determined whether or not the operation state of the compressor 11 is within the operation region A based on the intake air intake amount and the throttle opening.

  When it is determined that the throttle opening is equal to or greater than the determination opening, the process proceeds to step S14, where the ECU 30 opens the connection switching valve 26. If the valve has already been opened, the state is maintained. Thereafter, the current control routine is terminated.

  On the other hand, when it is determined that the intake air amount is less than the determination air amount, or when it is determined that the throttle opening is less than the determination opening, the process proceeds to step S15, and the ECU 30 closes the connection switching valve 26. If the valve has already been closed, the state is maintained. Thereafter, the current control routine is terminated.

  According to the supercharging system of the present embodiment, the seal plate 19 can be cooled using the thermoacoustic phenomenon by opening the connection switching valve 26 and vibrating the piston 23 by the intake pulsation. That is, the compressor 11 can be cooled by intake air pulsation without providing another drive source. Therefore, the compressor 11 can be cooled without deteriorating the fuel consumption of the engine 1. The temperature of the intake air at the outlet of the compressor 11 is high when the operation state of the compressor 11 is within the operation region A of FIG. Therefore, in such an operating state, oil is carbonized in the compressor 11 and coking is likely to occur. In the supercharging system of the present embodiment, the connection switching valve 26 is opened in such an operating state, and the connection switching valve 26 is closed in other operating states, so that the compressor 11 is wasted. The occurrence of coking can be sufficiently suppressed while being cooled. In addition, since the length L of the cooling passage 21 is set by the above-described equation (1), when the operation state of the compressor 11 is within the operation region A of FIG. A standing wave can be generated.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, the cooling passage may be connected to the exhaust manifold as shown in FIG. As is well known, pressure pulsation (exhaust pulsation) having a frequency corresponding to the engine speed is also generated in the exhaust passage. Therefore, a 1/4 wave standing wave may be generated in the cooling passage using this exhaust pulsation.

  The cooling method for cooling the outer peripheral end of the stack is not limited to cooling fins. It may be cooled by various means capable of dissipating heat to the outside. If the portion of the cooling passage between the open end and the stack can be placed adjacent to the diffuser, the inner end of the cooling passage is closed and the outer end is open. May be. In this case, the stack is provided near the end on the inner peripheral side, and the piston is provided on the end on the outer peripheral side. Further, the outer peripheral end is connected to the intake passage or the exhaust passage.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Intake passage 4 Exhaust passage 10 Turbo supercharger 11 Compressor 12 Turbine 13 Compressor housing 17 Diffuser part 19 Seal plate 21 Cooling passage 21a One end 21b Other end 22 Stack 22a Outer end (one end)
22b Inner peripheral end (the other end)
23 Piston (Piston member)
24 Cooling fin (cooling means)
25 connection passage 26 connection switching valve 30 engine control unit (control means)
L Length of the cooling passage C Number of cylinders of the internal combustion engine V Sonic speed N Number of rotations per minute of the internal combustion engine in an operating state in which the temperature of the intake air at the outlet of the compressor is the highest

Claims (5)

In a supercharging system for an internal combustion engine comprising a turbocharger that recovers exhaust energy in a turbine provided in an exhaust passage of the internal combustion engine and drives a compressor provided in the intake passage of the internal combustion engine,
A cooling passage provided in the compressor housing, having one end closed and the other end open, a piston member inserted in the other end of the cooling passage so as to be reciprocally movable, and 1/4 in the cooling passage. When a standing wave of a wavelength is generated, one end is located on the antinode side of the standing wave and the other end is located on the node side of the standing wave. A stack having a plurality of spaces communicating with the cooling passage, cooling means for cooling the one end of the stack, one of the intake passage and the exhaust passage, and the cooling passage A supercharging system for an internal combustion engine, comprising: a connection passage that connects the other end of the internal combustion engine.   The supercharging system for an internal combustion engine according to claim 1, wherein the cooling passage is provided in a seal plate that is a part of the diffuser portion so as to be adjacent to the diffuser portion of the housing. The internal combustion engine is configured as a four-cycle internal combustion engine having a plurality of cylinders,
The length of the cooling passage is 1 for the internal combustion engine in an operating state in which the length of the cooling passage is L, the number of cylinders of the internal combustion engine is C, the speed of sound is V, and the temperature of the intake air at the outlet of the compressor is highest. When the number of revolutions per minute is N, the following formula L = (V / N × C / 60/2) / 4
The supercharging system for an internal combustion engine according to claim 1 or 2, wherein the supercharging system is set so as to satisfy   A connection switching valve that opens and closes the connection passage; and a control unit that controls the connection switching valve so that the connection switching valve is opened in an operating state where the temperature of the intake air at the outlet of the compressor is highest. The supercharging system for an internal combustion engine according to any one of claims 1 to 3.   The supercharging system for an internal combustion engine according to any one of claims 1 to 4, wherein the cooling means is a plurality of cooling fins provided outside the housing.

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