JP2010048187A - Supercharger system for engine - Google Patents

Abstract

An engine supercharger system capable of improving a transient response during acceleration is provided.
An internal cooling water passage 58 is provided in a turbine housing 51, and an upstream end 581 is connected to a discharge side of a water pump 60 via an introduction pipe 59 and a water jacket 35, while a downstream end 582 is connected. Is connected to the suction side of the water pump 60 via the outlet pipe 61. An electric flow control valve 65 for controlling the flow rate of the cooling water with respect to the cooling water passage 58 in the housing by the opening degree of the valve body is provided on the downstream side of the connection portion of the introduction pipe 59 with the bypass passage 62. The acceleration state of the engine 1 is detected, that is, the engine speed is up to the minimum engine speed Ne1 when the throttle opening is 80% or more and the supercharging pressure of the intake air in the intake pipe 25 reaches the peak value P1. Is not reached, the engine ECU 4 performs control so that the opening degree of the electric flow control valve 65 is fully closed.
[Selection] Figure 1

Description

  The present invention relates to a supercharger system mounted on, for example, an automobile engine. In particular, the present invention relates to a measure for improving turbo efficiency.

  2. Description of the Related Art Conventionally, in an automobile engine, a turbocharger (hereinafter referred to as a turbocharger) that increases the air density by compressing intake air using the fluid energy of exhaust gas and thereby increasing the engine output is known. ing. In this turbocharger, a turbine shaft includes a turbine wheel provided in the turbine housing and disposed in the turbine housing, and a compressor wheel (also referred to as an impeller) disposed in the compressor housing and disposed in the intake passage. And a turbo rotor connected to each other. When the turbine wheel is rotated by the pressure of the exhaust gas, the rotational force is transmitted to the compressor wheel via the turbine shaft, and the intake air is supercharged toward the combustion chamber by the rotation of the compressor wheel.

  Further, since exhaust gas flows into the turbine housing, the heat load is high, and in order to ensure the durability and reliability of the turbine housing, a cooling medium flow passage is formed inside the turbine housing. On the other hand, by circulating a cooling medium, the thermal load of the turbine housing is suppressed to ensure durability reliability.

  Incidentally, an exhaust system of an engine for automobiles or the like is provided with a catalytic converter for purifying exhaust gas. In general, the catalytic converter uses a heat of the exhaust gas to heat a catalyst (for example, a three-way catalyst) and raises the catalyst to a predetermined activation temperature so as to exhibit an exhaust gas purification function. It has become. In that case, if the cooling medium flow passage is provided inside the turbine housing, the turbine housing may be supercooled by the cooling medium flowing through the cooling medium flow passage. Such a phenomenon appears prominently when the amount of heat of the exhaust gas is small, such as when the engine is in a light load operation or during cold start, and in this situation, the exhaust gas purification function is not exhibited until the catalyst temperature reaches the above activation temperature. Therefore, there has been a demand for a structure for rapidly increasing the catalyst temperature.

From this point, for example, in Patent Document 1 below, a flow rate control valve for controlling the flow rate of the cooling medium with respect to the cooling medium flow path is provided in the flow path through which the cooling medium flows with respect to the cooling medium flow path. When the amount of heat of the exhaust gas is small, such as during a load operation state or during cold start, the opening of the flow control valve is controlled to the closed side. This prevents overcooling by the cooling medium of the turbine housing when the heat quantity of the exhaust gas is small, such as when the engine is under light load operation or during cold start, and realizes early activation of the catalyst as the catalyst temperature rises rapidly is doing.
JP 61-49132 A

  By the way, the exhaust gas energy input to the turbine wheel is determined by the exhaust gas flow rate to the turbine wheel, the amount of heat of the exhaust gas flowing into the turbine housing, and the like. For this reason, if the cooling medium flows through the cooling medium flow passage inside the turbine housing during acceleration of the engine that requires a large amount of exhaust gas energy, the amount of heat of the exhaust gas flowing into the turbine housing cooled by the cooling medium is reduced. It will be small. As a result, sufficient exhaust gas energy cannot be obtained during engine acceleration, and the transient response during engine acceleration becomes poor.

  This invention is made | formed in view of this point, The place made into the objective is to provide the supercharger system of the engine which can improve the transient response at the time of acceleration.

-Principle of solving the problem-
The solution principle of the present invention taken to achieve the above object is to close the flow rate of the cooling medium flowing through the cooling medium flow passage inside the turbine housing when accelerating the engine that requires a large amount of exhaust gas energy. Further, the temperature drop of the turbine housing due to the cooling medium is suppressed, and sufficient exhaust gas energy can be obtained when the engine is accelerated.

-Solution-
Specifically, the present invention relates to a supercharging of an engine in which a turbine wheel housed in a turbine housing rotates by receiving fluid energy of exhaust gas and supercharges intake air by transmitting the rotational force to the compressor wheel. The machine system is assumed. A cooling medium flow passage formed in the turbine housing and a flow passage that controls the flow rate of the cooling medium with respect to the cooling medium flow passage. A control valve; and an opening detecting means for detecting the opening of the flow control valve. Furthermore, an engine acceleration state detection means for detecting the acceleration state of the engine, and a control means for controlling the opening degree of the flow control valve to the closed side when the engine acceleration state is detected by the engine acceleration state detection means, It has.

  With this specific matter, when the engine acceleration state is detected by the engine acceleration state detection means, the opening degree of the flow rate control valve for controlling the flow rate of the coolant to the coolant flow path inside the turbine housing is closed by the control means. Therefore, the flow of the cooling medium to the cooling medium flow passage inside the turbine housing is prohibited during acceleration of the engine, and the temperature drop of the turbine housing due to the cooling medium is suppressed. As a result, sufficient exhaust gas energy is obtained during engine acceleration, the boost pressure rises quickly, and transient response during engine acceleration can be improved.

  In particular, the following configuration is listed as a condition for performing control for switching the opening degree of the flow control valve from the closed side to the open side when the engine is accelerated. That is, the engine acceleration state detecting means is provided with engine speed detecting means for detecting the engine speed and load state detecting means for detecting the load state of the engine. Further, a minimum engine speed at which the supercharging pressure of the intake air reaches a peak value is stored in the control means. And when the load state detecting means detects that the engine is in a high load state and the engine speed detecting means detects that the engine speed has reached the minimum engine speed. The opening of the flow control valve is controlled to the open side by the control means.

  Even if the flow of the cooling medium to the cooling medium flow path inside the turbine housing is prohibited by the control to the closed side of the flow control valve during acceleration of the engine due to this specific matter, the engine speed is the minimum engine speed at high load. If the number reaches the value, the boost pressure cannot be increased any further. Therefore, the opening of the flow control valve is controlled to open and the cooling medium is circulated through the cooling medium flow passage inside the turbine housing to cool the turbine housing. Thus, it is possible to ensure the durability of the turbine housing while ensuring a transient response during acceleration of the engine.

  Moreover, the following structures are mentioned as a thing used also as a countermeasure which prevents the oil coking of the turbine shaft which connects a turbine wheel and a compressor wheel. That is, bearing housing temperature detecting means for detecting the temperature of the bearing housing of the turbine shaft connecting the turbine wheel and the compressor wheel is provided. When the engine speed detecting means detects that the engine speed has become smaller than the speed corresponding to the low load state by the load condition detecting means after the acceleration state of the engine is finished, The opening of the flow control valve is controlled to the closed side by means, but the temperature in the bearing housing detected by the bearing housing temperature detection means has reached the oil coking guarantee limit temperature of the turbine shaft. Is detected, the opening degree of the flow control valve is controlled to the open side.

  Due to this specific matter, the opening degree of the flow control valve controlled to the closed side when the engine speed becomes smaller than the speed corresponding to the low load state by the load state detection means after the acceleration state of the engine is finished. If the temperature in the bearing housing reaches the oil coking guarantee limit temperature of the turbine shaft, it is controlled to the open side, so that the engine speed that is lower than the engine speed corresponding to the low load state after the engine is accelerated, that is, When the engine is idling or running at low load, the turbine housing or the bearing housing that reaches the oil coking guarantee limit temperature of the turbine shaft due to heat conduction from the turbine wheel in the accelerated state of the engine Cooled by the cooling medium flowing through the cooling medium flow passage Quickly cools down the oil coking assurance limit temperature of the turbine shaft. This makes it possible to prevent turbine shaft oil coking during idling rotation or low load running after the acceleration state of the engine is finished.

  Further, the following configuration is listed as a measure for improving the shut-off performance at the cold start of the engine. That is, cooling water for engine cooling is applied as a cooling medium flowing through the flow path to the cooling medium flow path, and the cooling water from the engine is bypassed in the flow path. A bypass passage that circulates in a short circuit is provided, and a cooling water temperature detecting means that detects the temperature of the cooling water flowing through the bypass passage is provided in the bypass passage. Then, the control means controls the opening of the flow control valve to the closed side until the temperature of the cooling water detected by the cooling water temperature detecting means at the time of cold start of the engine reaches the warm-up completion temperature. is doing.

  With this specific matter, the opening degree of the flow control valve is controlled to the closed side by the control means until the temperature of the cooling water flowing through the cooling medium flow passage reaches the warm-up completion temperature when the engine is cold started. Therefore, the low-temperature (temperature before reaching the warm-up completion temperature) cooling water heated by the engine immediately after the low-temperature start flows into the cooling medium flow passage inside the turbine housing having a large heat capacity, thereby generating heat. The deprivation is avoided and the bypass passage is circulated, so that it is possible to improve the warm-up performance when the engine is cold started.

  In short, by controlling the opening of the flow rate control valve that controls the flow rate of the coolant to the coolant flow path inside the turbine housing during engine acceleration to the closed side, the temperature drop of the turbine housing due to the coolant is suppressed. Sufficient exhaust gas energy can be obtained at the time of engine acceleration, and the boost pressure rises quickly, and the transient response at the time of engine acceleration can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a single turbo turbocharger mounted on an automobile engine will be described. The present invention is not limited to this, and the present invention can also be applied to a hybrid turbocharging system provided with a twin turbo turbocharger, a sequential turbo turbocharger, and a supercharger.

  First, a diesel engine to which the present invention is applied will be described.

-Engine-
A schematic configuration of an engine to which the present invention is applied will be described with reference to FIG. FIG. 1 shows only the configuration of one cylinder of the engine.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  An engine 1 shown in FIG. 1 is, for example, an in-line four-cylinder gasoline engine, and a piston 12 that reciprocates in the vertical direction is provided in a cylinder block 11 that constitutes each cylinder. The piston 12 is connected to the crankshaft 22 via the connecting rod 21, and the reciprocating motion of the piston 12 is converted into rotation of the crankshaft 22 by the connecting rod 21.

  A signal rotor 23 is attached to the crankshaft 22. A plurality of protrusions (teeth) 231, 231,... Are provided at equal angles on the outer peripheral surface of the signal rotor 23. In the vicinity of the side of the signal rotor 23, an engine speed sensor (crank position sensor) 24 is disposed as an engine speed detecting means. The engine speed sensor 24 is, for example, an electromagnetic pickup, and generates a pulsed signal (output pulse) corresponding to the protrusion 231 of the signal rotor 23 when the crankshaft 22 rotates.

  A cylinder head 13 is provided at the upper end of the cylinder block 11 of the engine 1, and a combustion chamber 14 is formed between the cylinder head 13 and the piston 12. The combustion chamber 14 is connected to a surge tank 252 through an intake branch pipe 251. The surge tank 252 is connected to the air flow meter 253 via the intake pipe 25, and the air flow meter 253 is connected to the air cleaner 254. A throttle valve 26 driven by a motor 261 such as a DC motor is provided inside the intake pipe 25, and an opening degree (throttle opening degree) of the throttle valve 26 is detected by a throttle opening degree sensor 27 as a load state detecting means. Has been. In this case, the engine speed sensor 24 and the throttle opening sensor 27 constitute an engine acceleration state detection means 20 (appearing in FIG. 2) that detects the acceleration state of the engine 1.

  The intake branch pipe 251 is attached with an injector 28 as a fuel injection valve that injects fuel toward the intake branch pipe 251 (intake port). The injector 28 is controlled based on an output signal of an engine control circuit (hereinafter referred to as “engine ECU”) 4 as control means.

  An ignition plug 30 is attached to the cylinder head 13 of the engine 1 for each combustion chamber 14, and the air-fuel mixture in the combustion chamber 14 is ignited by the spark discharge of each ignition plug 30. The intake valve 31 and the exhaust valve 32 of the engine 1 are provided with variable valve timing mechanisms 33 and 34 that change the opening / closing timing, respectively. The cylinder block 11 of the engine 1 is provided with a water jacket 35 through which cooling water as a cooling medium circulates.

  On the other hand, the combustion chamber 14 of the engine 1 is connected to an exhaust pipe 29 via an exhaust manifold 291. The exhaust pipe 29 is provided with a catalyst 292 for purifying exhaust gas. As the catalyst 292, a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas is used.

  As shown in FIG. 2, the engine ECU 4 is composed of a digital computer, and is connected to each other via a bidirectional bus 41, a ROM (read only memory) 42, a RAM (random access memory) 43, and a CPU (microprocessor). 44, an input port 45 and an output port 46. The air flow meter 253 generates an output voltage proportional to the amount of intake air, and the output voltage of the air flow meter 253 is input to the input port 45 via the AD converter 47. The throttle opening sensor 27 generates an output voltage proportional to the opening of the throttle valve 26 (throttle opening). The output voltage of the throttle opening sensor 27 is input to the input port 45 via the AD converter 47. Yes. The engine speed sensor 24 is connected to an input port 45, and a crank angle and an engine speed are calculated based on an output signal (pulse signal) from the engine speed sensor 24. On the other hand, the output port 46 is connected to the motor 261, the injector 28, the spark plug 30, and the variable valve timing mechanisms 33 and 34 on the intake side and the exhaust side via corresponding drive circuits 48, respectively. In this case, the engine ECU 4 executes various control routines stored in the ROM 42 to control the fuel injection amount and fuel injection timing of the injector 28, the ignition timing of the spark plug 30 and the like according to the operating state of the engine 1. At the same time, the variable valve timing mechanisms 33 and 34 on the intake side and the exhaust side are controlled so that the actual valve timings of the intake valve 31 and the exhaust valve 32 coincide with the target valve timing.

-Configuration explanation of turbocharger-
The turbocharger 5 is accommodated in a turbine housing 51 provided in an exhaust manifold 291 of the engine 1 and is provided in a turbine wheel 52 that is rotated by exhaust gas fed into the turbine housing 51 and an intake pipe 25 of the engine 1. And a compressor wheel 54 for receiving the rotational force of the turbine wheel 52 and forcibly sending air (intake air) into the combustion chamber 14.

  The turbine wheel 52 and the compressor wheel 54 are connected to each other by a metal (for example, cast iron) turbine shaft 55 so as to be integrally rotatable. That is, the turbine wheel 52, the compressor wheel 54, and the turbine shaft 55 are arranged on the same axis, and are integrally assembled to constitute the turbo rotor 50. As the turbine wheel 52 rotates, the turbine shaft 55 and the compressor are combined. The wheel 54 is configured to rotate around this axis.

  The turbine wheel 52 includes a large number of turbine blades 521, 521,. The turbine wheel 52 is made of heat-resistant steel (carbon steel) because it is exposed to high-temperature (for example, 600 to 800 ° C.) exhaust gas. The turbine housing 51 is formed with a scroll chamber 511 having a spiral shape so as to surround the turbine wheel 52. The scroll chamber 511 has an exhaust gas inlet 512 that opens in the tangential direction of the turbo rotor 50 and an exhaust gas discharge port 513 that opens in the axial direction of the turbo rotor 50. The exhaust gas intake 512 is connected to the exhaust manifold 291 of the engine 1, and the exhaust gas discharge 513 is connected to the exhaust pipe 29 that guides the exhaust gas to the catalyst 292.

  On the other hand, the compressor wheel 54 includes a large number of compressor blades 541, 541,. The compressor wheel 54 is made of a lightweight aluminum alloy or synthetic resin in order to suppress turbo lag. A spiral diffuser 531 is formed in the compressor housing 53 so as to surround the compressor wheel 54. The diffuser 531 has an intake air intake port 532 that opens in the axial direction of the turbo rotor 50, and an intake air discharge port 533 that opens in the tangential direction of the turbo rotor 50. The intake air intake port 532 is connected to an air cleaner 254, and the intake air discharge port 533 is connected to the intake pipe 25 of the engine. An intercooler 255 for cooling the intake air supercharged by the turbocharger 5 is provided in the middle of the intake pipe 25.

  The shape of the turbine wheel 52 is not particularly limited, and an impact type, a reflection type, a mixed flow type, or the like can be adopted. Similarly, the shape of the compressor wheel 54 is not particularly limited, and a radial type, a backward type, a backward lake type, and the like can be adopted. In the turbo rotor 50 according to the present embodiment, the turbine wheel 52, the compressor wheel 54, and the turbine shaft 55 are formed as separate bodies, and these are integrally assembled. Good.

  The turbine shaft 55 is inserted through a bearing member 561 formed in the bearing housing 56. The bearing member 561 has a cylindrical space formed therein, and both ends of the inner circumferential surface in the axial direction, that is, both ends in the longitudinal direction of the turbine shaft 55 (locations close to the turbine wheel 52 and the compressor wheel 54). Bearing metals 562 and 563 are loosely fitted in two adjacent places). Further, the inner peripheral surfaces of the bearing metals 562 and 563 are loosely fitted to the turbine shaft 55. That is, the bearing metals 562 and 563 are disposed in the sliding portion between the turbine shaft 55 and the bearing member 561. Further, lubricating oil is supplied to the bearing metals 562 and 563 from a lubricating oil supply passage 57 formed in the bearing housing 56. By supplying the lubricating oil, an oil film is formed between the inner peripheral surface of the bearing member 561 and the outer peripheral surfaces of the bearing metals 562 and 563. On the other hand, each bearing metal 562, 563 is formed with oil supply holes 571, 571 penetrating from the outer peripheral surface to the inner peripheral surface. Accordingly, the lubricating oil supplied to the outer peripheral surface of each bearing metal 562, 563 is also supplied to the inner peripheral surface of the bearing metal 562, 563 via the oil supply holes 571, 571, and the inner diameter of each bearing metal 562, 563 is increased. An oil film is also formed between the peripheral surface and the outer peripheral surface of the turbine shaft 55. Thus, the bearing system of the turbine shaft 55 in the present embodiment is a so-called floating bearing system, and the bearing metals 562 and 563 can freely rotate between the turbine shaft 55 and the bearing member 561. It has become. The bearing metals 562 and 563 are restricted from moving in the axial direction by snap rings 564 and 564.

  The bearing housing 56 is made of the same material (for example, cast iron) as the turbine shaft 55. As a result, the amount of expansion of the bearing housing 56 due to heat and the amount of expansion of the turbine shaft 55 are made substantially equal, and a good bearing state is continuously maintained. Moreover, it is preferable that the constituent material of the compressor wheel 54 and the compressor housing 53 is also the same material.

  Further, in the turbine housing 51, a cooling water passage in the housing as a cooling medium flow passage having a substantially C-shaped cross section formed so as to cover the scroll chamber 511 from the radially outer side to substantially the entire circumference. 58 is provided. The cooling water passage 58 in the housing has an upstream end 581 connected to the discharge side of the water pump 60 via an introduction pipe 59 as a flow passage, while a downstream end 582 has a lead-out piping 61 as a flow passage. It is connected to the suction side of the water pump 60 via Further, the upstream end of the introduction pipe 59 and the downstream end of the outlet pipe 61 are connected to the water jacket 35 of the engine 1, respectively. For this reason, as the water pump 60 is driven, cooling water is introduced from the water jacket 35 of the engine 1 through the introduction pipe 59 to the cooling water passage 58 in the housing, and the turbine housing 51 is cooled by this cooling water. The coolant is discharged to the water jacket 35 of the engine 1 after returning to the water pump 60 through the outlet pipe 61. This cooling water is cooled by a radiator as needed.

  A bypass passage 62 that bypasses the in-housing cooling water passage 58 and circulates the cooling water from the water jacket 35 of the engine 1 in a short circuit is provided between the introduction piping 59 and the outlet piping 61. The bypass passage 62 is provided with a heater core 63 and a cooling water temperature sensor 64 as a cooling water temperature detecting means for detecting the temperature of the cooling water flowing through the bypass passage 62 at a position immediately upstream of the heater core 63. ing. An electric flow control valve (flow control valve) that controls the flow rate of the cooling water with respect to the in-housing cooling water passage 58 based on the opening of the valve body is provided downstream of the connection portion of the introduction pipe 59 with the bypass passage 62. 65 is provided. In the vicinity of the electric flow control valve 65, a valve body opening sensor 66 is provided as an opening detection means for detecting the opening of the valve body of the electric flow control valve 65.

  Further, an approximate temperature of the bearing housing 56 transmitted between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side via the turbine housing 51 is detected at a position near the turbine wheel 52 of the turbine housing 51. A bearing housing temperature sensor (bearing housing temperature detecting means) 67 is provided. Further, an exhaust gas temperature sensor 68 for detecting the amount of heat of the exhaust gas flowing into the scroll chamber 511 of the turbine housing 51, that is, the temperature of the exhaust gas, is provided at the downstream end of the exhaust manifold 291. Furthermore, a supercharging pressure sensor 69 that detects the supercharging pressure of the intake air supercharged by the turbocharger 5 is provided in the intake pipe 25 upstream of the intercooler 255. The cooling water temperature sensor 64 generates an output voltage proportional to the cooling water temperature, and the output voltage of the cooling water temperature sensor 64 is input to the input port 45 via the AD converter 47. The valve element opening sensor 66 generates an output voltage proportional to the opening of the valve element, and the output voltage of the valve element opening sensor 66 is input to the input port 45 via the AD converter 47. The bearing housing temperature sensor 67 generates an output voltage proportional to the approximate temperature of the bearing housing 56, and the output voltage of the bearing housing temperature sensor 67 is input to the input port 45 via the AD converter 47. The exhaust gas temperature sensor 68 generates an output voltage proportional to the temperature of the exhaust gas flowing into the scroll chamber 511 of the turbine housing 51, and the output voltage of the exhaust gas temperature sensor 68 is supplied to the input port 45 via the AD converter 47. Have been entered. Further, the supercharging pressure sensor 69 generates an output voltage proportional to the supercharging pressure, and the output voltage of the supercharging pressure sensor 69 is input to the input port 45 via the AD converter 47. In this case, the ROM 42 of the engine ECU 4 stores the minimum engine speed Ne1 (appears in FIG. 3) when the supercharging pressure of the intake air in the intake pipe 25 reaches the peak value P1 (appears in FIG. 3). Has been.

  The feature of this embodiment is that the electric flow control valve 65 connected to the output port 46 via the drive circuit 48 is controlled by various control routines stored in the ROM 42 of the engine ECU 4 according to the operating state of the engine 1. There is to control. This will be specifically described below.

  The engine ECU 4 detects the acceleration state of the engine 1 by the engine acceleration state detection means 20 including the engine speed sensor 24 and the throttle opening degree sensor 27, that is, the throttle opening degree is not less than a predetermined opening degree (for example, 80% or more). As shown in FIG. 3, when the engine speed has not reached the minimum engine speed Ne1 when the supercharging pressure of the intake air in the intake pipe 25 reaches the peak value P1, the electric flow control valve The opening of the 65 valve element is controlled to be fully closed. When the engine speed reaches the minimum engine speed Ne1, the opening of the valve body of the electric flow control valve 65 is controlled to be gradually opened toward the fully open side. At this time, as shown by a one-dot chain line in FIG. 3, when the opening degree of the electric flow control valve 65 is fully opened regardless of the acceleration state of the engine 1, Since engine cooling water has been introduced, the temperature of the exhaust gas flowing into the scroll chamber 511 of the turbine housing 51 cooled by this cooling water is such that the supercharging pressure of the intake air in the intake pipe 25 reaches the peak value P1. Even at this point, it is still lower than that of the present invention in which the opening degree of the electric flow control valve 65 indicated by a solid line in FIG. It can be seen that the amount of heat of the exhaust gas flowing into the is sufficiently large. Thereby, in the present invention (shown by a solid line in FIG. 3), the opening degree of the electric flow control valve 65 is fully opened regardless of the acceleration state of the engine 1 (one point in FIG. 3). Compared to the one indicated by the chain line), the time for the supercharging pressure of the intake air supercharged by the turbocharger 5 to reach the peak value P1 is earlier, and until the minimum engine speed Ne1 when the peak value P1 is reached. It can be seen that the engine speed of the engine rises faster and sufficient exhaust gas energy is obtained when the engine 1 is accelerated.

  Further, as shown in FIG. 4, the engine ECU 4 has made the engine speed smaller than the speed Ne2 (for example, 1200 rpm) corresponding to the low load state by the throttle opening sensor 27 after the acceleration state of the engine 1 is finished. For example, when the engine is detected, such as during idling rotation or low load running, the opening of the valve body of the electric flow control valve 65 is controlled to be closed, but the bearing housing temperature The approximate temperature of the bearing housing 56 by the sensor 67 is the oil coking guarantee limit temperature Tc (for example, 200 ° C.) of the turbine shaft 55, specifically, the oil between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side. When it is detected that the coking guarantee limit temperature Tc has been reached, the electric flow control valve 65 It is controlled so that the opening of the valve body is opened. At this time, when the engine rotation speed is smaller than the rotation speed Ne2 (for example, 1200 rpm), the bearing housing temperature sensor 67 detects that the temperature of the bearing housing 56 is lower than the oil coking guarantee limit temperature Tc. The opening degree of the valve body of the electric flow control valve 65 is controlled to the closed side. In this case, the oil coking guarantee limit temperature Tc between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side is stored in advance in the ROM 42 of the engine ECU 4 as an approximate temperature of the bearing housing 56.

  Further, as shown in FIG. 5, the engine ECU 4 causes the temperature of the cooling water in the bypass passage 62 detected by the cooling water temperature sensor 64 when the engine 1 is cold started to reach a warm-up completion temperature Td (for example, 70 ° C.). In the meantime, the opening degree of the valve body of the electric flow control valve 65 is controlled to be fully closed. When the temperature of the coolant in the bypass passage 62 detected by the coolant temperature sensor 64 when the engine 1 is cold started reaches a warm-up completion temperature Td (for example, 70 ° C.), the electric flow control valve 65 Control is performed so that the opening of the valve element is gradually opened toward the fully open side.

  Therefore, in the above embodiment, the acceleration state of the engine 1 is detected by the engine acceleration state detection means 20, that is, the throttle opening is equal to or greater than a predetermined opening (for example, 80% or more), and the intake in the intake pipe 25 is performed. When the engine speed has not reached the minimum engine speed Ne1 when the air supercharging pressure reaches the peak value P1, the opening degree of the valve body of the electric flow control valve 65 is fully closed by the engine ECU 4. Is controlled. Thereby, when the engine 1 is accelerated, the circulation of the cooling water to the in-housing cooling water passage 58 inside the turbine housing 51 is prohibited, and the temperature drop of the turbine housing 51 due to the cooling water is suppressed. As a result, sufficient exhaust gas energy is obtained when the engine 1 is accelerated, the boost pressure rises quickly, and the transient response during acceleration of the engine 1 can be improved.

  On the other hand, when the engine speed reaches the minimum engine speed Ne1, the opening degree of the valve body of the electric flow control valve 65 is controlled by the engine ECU 4 so as to gradually open toward the fully open side. Even when the engine 1 is accelerated, the throttle opening is predetermined even though the flow of the cooling water to the in-housing cooling water passage 58 inside the turbine housing 51 is prohibited by the control of the electric flow control valve 65 to fully close the valve body. If the engine speed reaches the minimum engine speed Ne1 when the opening is equal to or greater than the opening (for example, 80% or more), the boost pressure cannot be further increased, so that the valve body of the electric flow control valve 65 is opened. The turbine housing 51 may be cooled by flowing the cooling water through the in-housing cooling water passage 58 inside the turbine housing 51 by controlling the degree of opening to the open side. While ensuring the transient response during acceleration Jin 1, it is possible to achieve the durability of the turbine housing 51.

  Further, under the situation where it is detected that the engine rotation speed has become smaller than the rotation speed Ne2 (for example, 1200 rpm) corresponding to the low load state by the throttle opening sensor 27 after the acceleration state of the engine 1 is finished, for example, idling rotation Although the opening degree of the valve body of the electric flow control valve 65 is controlled to be closed by the engine ECU 4 under circumstances such as when driving or when driving under a low load, the approximate temperature of the bearing housing 56 by the bearing housing temperature sensor 67 is It is detected that the oil coking guarantee limit temperature Tc (for example, 200 ° C.) of the turbine shaft 55, specifically, the oil coking guarantee limit temperature Tc between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side has been reached. Then, the opening degree of the electric flow control valve 65 is opened. It is controlled so. As a result, when the engine speed is equal to or lower than the rotation speed Ne2 corresponding to the low load state, that is, during idling rotation or low load traveling, the heat from the turbine housing 51 and the turbine wheel 52 in the acceleration state of the engine 1 The bearing housing 56 that is heated by conduction and reaches the oil coking guarantee limit temperature Tc of the turbine shaft 55 is cooled by the cooling water flowing to the in-housing cooling water passage 58 inside the turbine housing 51, and the oil coking of the turbine shaft 55 is performed. The temperature quickly decreases from the guaranteed limit temperature Tc. As a result, oil coking between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side during idling rotation or low load running after the acceleration state of the engine 1 is finished can be prevented.

  On the other hand, under conditions such as idling rotation or low-load running where the engine speed is smaller than the above-mentioned speed Ne2 (for example, 1200 rpm), the approximate temperature of the bearing housing 56 is determined by the bearing housing temperature sensor 67 so that the turbine shaft 55 and the turbine When it is detected that the temperature is below the oil coking guarantee limit temperature Tc with the bearing metal 562 on the wheel 52 side, the opening degree of the valve body of the electric flow control valve 65 is controlled to the closed side. If the approximate temperature of the housing 56 falls below the oil coking guarantee limit temperature Tc, the flow of the cooling water to the in-housing cooling water passage 58 inside the turbine housing 51 is interrupted, and the cooling of the turbine housing 51 is prohibited. Keep the temperature at the optimum temperature for acceleration It will be. As a result, oil coking between the turbine shaft 55 and the bearing metal 562 on the turbine wheel 52 side is ensured while ensuring a transient response during acceleration of the engine 1 from a situation such as idling rotation or low load running. Can be prevented.

  Further, until the temperature of the cooling water in the bypass passage 62 detected by the cooling water temperature sensor 64 at the time of cold start of the engine 1 reaches the warm-up completion temperature Td (for example, 70 ° C.), the engine ECU 4 performs the electric flow rate. Since the opening degree of the valve body of the control valve 65 is controlled to be fully closed, the low-temperature (temperature before reaching the warm-up completion temperature) cooling water heated by the engine 1 immediately after the cold start is It is avoided that heat is taken away by circulating to the in-housing cooling water passage 58 inside the turbine housing 51 having a large heat capacity, and is circulated through the bypass passage 62. The machine performance can be improved, and the temperature raising performance of the heater core 63 of the bypass passage 62 can be improved.

  On the other hand, when the temperature of the cooling water in the bypass passage 62 detected by the cooling water temperature sensor 64 at the cold start of the engine 1 reaches the warm-up completion temperature Td (for example, 70 ° C.), the engine ECU 4 controls the electric flow rate. Since the opening degree of the valve body of the control valve 65 is controlled to be gradually opened toward the fully open side, the cooling water heated to the warm-up completion temperature Td is the cooling water passage in the housing inside the turbine housing 51. The turbine housing 51 can be warmed with cooling water in preparation for acceleration of the engine 1.

  In addition, this invention is not limited to the said embodiment, The other various modifications are included. For example, in the above embodiment, the case where the present invention is applied to the turbocharger 5 mounted on the automobile diesel engine has been described. The present invention is not limited to this and can be applied to a gasoline engine or the like. The engine to which the present invention is applicable is not limited to an automobile engine.

  In the above embodiment, the engine speed detection means 20 is configured by the engine speed sensor 24 and the throttle opening sensor 27. However, an accelerator opening detection means is used instead of the throttle opening sensor as the load state detection means. The accelerator opening degree detecting means and the engine speed sensor may constitute engine acceleration state detecting means. Further, the engine acceleration state detecting means may be constituted by a throttle opening sensor, an accelerator opening detecting means and an engine speed sensor.

  Further, in the above-described embodiment, the valve body of the electric flow control valve 65 is changed according to the approximate temperature of the bearing housing 56 under conditions such as idling rotation after running the acceleration state of the engine 1 or low-load running. The degree of opening of the electric flow control valve is controlled according to the approximate temperature of the bearing housing when the engine is stopped after the acceleration state of the engine is finished. It may be controlled to open side or close side.

  Further, in the above embodiment, the cooling water of the engine 1 is used as a cooling medium for cooling the turbine housing 51. However, the cooling water is not limited to the engine cooling water, and engine oil, fuel, or the like is used as the cooling medium. It is also possible.

It is a longitudinal section showing an engine supercharger system concerning an embodiment of the present invention. It is a block diagram which shows the structure of control systems, such as engine ECU. It is a time chart which shows the engine speed, the supercharging pressure of intake air, the temperature of exhaust gas, and the opening characteristic of the valve body of an electric flow control valve. It is a time chart which shows the engine speed, the approximate temperature of a bearing housing, and the opening degree characteristic of the valve body of an electric flow control valve. It is a time chart which shows the characteristic of the temperature of a cooling water, and the opening degree of the valve body of an electric flow control valve.

Explanation of symbols

1 Engine 20 Engine acceleration state detecting means 24 Engine speed sensor (engine speed detecting means)
27 Throttle opening sensor (load state detection means)
4 Engine ECU (control means)
5 Turbocharger (supercharger)
51 Turbine housing 52 Turbine wheel 54 Compressor wheel 55 Turbine shaft 58 Cooling water passage in housing (cooling medium flow passage)
59 Introduction piping (flow passage)
61 Lead piping (flow passage)
62 Bypass passage 64 Cooling water temperature sensor (cooling water temperature detecting means)
65 Electric flow control valve (Flow control valve)
66 Valve body opening sensor (opening detection means)
67 Bearing housing temperature sensor (bearing housing temperature detection means)
Ne1 Minimum engine speed Ne2 when the boost pressure reaches the peak value Ne2 Engine speed P1 corresponding to the low load state Peak value Tc of boost pressure Tc Oil coking guarantee limit temperature Td Warm-up completion temperature

Claims (4)

In a turbocharger system of an engine in which a turbine wheel accommodated in a turbine housing rotates by receiving fluid energy of exhaust gas and supercharges intake air by transmitting the rotational force to a compressor wheel.
A cooling medium flow passage formed in the turbine housing;
A flow rate control valve that is interposed in a flow path that circulates the cooling medium with respect to the cooling medium flow path, and that controls a flow rate of the cooling medium with respect to the cooling medium flow path;
An opening degree detecting means for detecting the opening degree of the flow control valve;
Engine acceleration state detection means for detecting the acceleration state of the engine;
A supercharger system for an engine comprising: control means for controlling the opening of the flow control valve to a closed side when the engine acceleration state is detected by the engine acceleration state detection means. The engine supercharger system according to claim 1,
The engine acceleration state detection means includes
Engine speed detecting means for detecting the engine speed;
Load state detection means for detecting the load state of the engine,
The control means includes
The minimum engine speed when the supercharging pressure of the intake air reaches the peak value is stored,
When the load state detecting means detects that the engine is in a high load state and the engine speed detecting means detects that the engine speed has reached the minimum engine speed, An engine supercharger system, wherein the opening degree of the flow control valve is controlled to the open side. The engine supercharger system according to claim 2,
A bearing housing temperature detecting means for detecting a temperature of a bearing housing of a turbine shaft connecting the turbine wheel and the compressor wheel;
When the control means detects that the engine speed has become smaller than the speed corresponding to the low load state by the load condition detection means by the engine speed detection means after finishing the acceleration state of the engine. Although the opening degree of the flow control valve is controlled to the closed side, it is detected that the temperature in the bearing housing detected by the bearing housing temperature detecting means has reached the oil coking guarantee limit temperature of the turbine shaft. Then, the engine supercharger system is characterized in that the opening degree of the flow control valve is controlled to the open side. In the supercharger system of the engine according to any one of claims 1 to 3,
As a cooling medium flowing through the cooling medium flow path through the flow path, cooling water for engine cooling is applied,
The flow passage is provided with a bypass passage that bypasses the cooling medium flow passage and circulates the cooling water from the engine in a short-circuit manner, and the bypass passage has a cooling water flowing through the bypass passage. Cooling water temperature detection means for detecting the temperature of the
The control means controls the opening degree of the flow control valve to the closed side until the temperature of the cooling water detected by the cooling water temperature detecting means at the time of cold start of the engine reaches the warm-up completion temperature. An engine supercharger system characterized by having

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