JP2013217382A - Engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine capable of precisely controlling a multistage variable supercharging system.SOLUTION: When a first condition 11 and a second condition 12 are satisfied, an ECU 60 determines that a current high-pressure turbo rotation speed Nta_hp is a supercharger rotation speed of a high-pressure supercharger at which a multistage variable supercharging system 20 operates most efficiently and a boost pressure Bpa is a supercharging pressure optimizing an engine combustion state. When the first condition 11 or the second condition 12 is not satisfied, the ECU determines that the current high-pressure turbo rotation speed Nta_hp is not the supercharger rotation speed of the high-pressure supercharger at which the multistage variable supercharging system 20 operates most efficiently or the boost pressure Bpa is not the supercharging pressure optimizing the engine combustion state, and adjusts a vane opening of a movable vane 25 until the first condition 11 is satisfied, and then adjusts the vane opening of the movable vane 25 until the second condition 12 is satisfied.

Description

  The present invention relates to an engine technology including a multistage variable supercharging system.

  Conventionally, a supercharging system in which a high-pressure supercharger and a low-pressure supercharger are arranged in series is known. Also known is a supercharger comprising variable capacity means for increasing the charging effect by changing the flow rate of the exhaust gas. Here, a supercharging system in which two superchargers are arranged in series and at least one of the superchargers includes variable capacity means is defined as a multistage variable system supercharging system. For example, patent document 1 is disclosing the engine provided with a multistage variable supercharging system.

  Conventionally, for example, a control unit for a supercharger such as a variable capacity unit has used a boost pressure detected by a boost sensor as a feedback value. However, since the supercharging pressure is an indirect physical quantity with respect to the operation of the supercharger, the supercharger control means using the supercharging pressure as a feedback value is disadvantageous in that the supercharger cannot be controlled accurately. there were. In particular, an engine having a multistage variable supercharging system is disadvantageous in that the supercharging system cannot be controlled with high accuracy by the control means using the supercharging pressure as a feedback value.

JP 2006-29110 A

  The present invention controls the high-pressure supercharger rotation speed of the high-pressure supercharger that is directly related to the operation of the high-pressure supercharger as a feedback value so that the supercharging pressure that optimizes the combustion state of the engine is obtained. Accordingly, an object of the present invention is to provide an engine that can accurately control a multistage variable system supercharging system in which a high-pressure supercharger and a low-pressure supercharger are arranged in series.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  In Claim 1, the high-pressure supercharger which consists of a high-pressure compressor (21) and a high-pressure turbo (22), and the low-pressure supercharger which consists of a low-pressure compressor (31) and a low-pressure turbo (32) are arrange | positioned in series. The multistage variable system supercharging system (20), the boost sensor (62) for detecting the boost pressure in the intake manifold (12), and the high pressure compressor (21) are provided to detect the rotational speed of the high pressure turbo (22). A high-pressure turbo sensor (61), a movable vane (25) that adjusts the capacity of the high-pressure turbo (22), and an ECU (60) that is a control means for adjusting the opening of the movable vane (25). The ECU (60) is based on the boost pressure detected by the boost sensor (62) and the high-pressure turbo rotational speed detected by the high-pressure turbo sensor (61). There are, and adjusts the vane opening of the movable vanes (25).

  In Claim 1, the high-pressure supercharger which consists of a high-pressure compressor (21) and a high-pressure turbo (22), and the low-pressure supercharger which consists of a low-pressure compressor (31) and a low-pressure turbo (32) are arrange | positioned in series. The multistage variable system supercharging system (20), the boost sensor (62) for detecting the boost pressure in the intake manifold (12), and the high pressure compressor (21) are provided to detect the rotational speed of the high pressure turbo (22). A high-pressure turbo sensor (61), a movable vane (25) that adjusts the capacity of the high-pressure turbo (22), and an ECU (60) that is a control means for adjusting the opening of the movable vane (25). When the engine (100) has a low rotation speed and a low load, the ECU (60) performs a target high-pressure turbo rotation speed (ωctrg) at which the high-pressure supercharger operates most efficiently. hp) and a target boost pressure (Bpatrg) as a supercharging pressure that optimizes the combustion state of the engine (100) are calculated from a map stored in advance in the ECU 60, and the ECU (60) As a condition (11), the absolute value of the difference between the high-pressure turbo rotational speed (Nta_hp) detected by the high-pressure turbo sensor (61) and the target high-pressure turbo rotational speed (ωctrg_hp) is a first predetermined value (α11). The ECU (60) determines whether or not the difference is smaller than the boost pressure (Bpa) detected by the boost sensor (62) and the target boost pressure (Bpatrg) as the second condition (12). Is determined whether the absolute value is smaller than a second predetermined value (α12), and the ECU (60) determines whether the first condition (11) and the second condition are satisfied. If the condition (12) is satisfied, the current high-pressure turbo rotational speed (Nta_hp) is the turbocharger speed of the high-pressure supercharger in which the multistage variable turbocharger system (20) operates most efficiently, and boost The pressure (Bpa) is determined to be a supercharging pressure that optimizes the combustion state of the engine (100), and the ECU (60) does not satisfy the first condition (11) or the second condition (12). In this case, the current high-pressure turbo speed (Nta_hp) is not the supercharger speed of the high-pressure supercharger in which the multistage variable system supercharging system (20) operates most efficiently, or the boost pressure (Bpa) is the engine The ECU (60) determines that the combustion pressure of (100) is not optimal, and the ECU (60) adjusts the vane opening of the movable vane (25) until the first condition (11) is satisfied, Next, the ECU (60) And adjusts the vane opening of the movable vanes (25) to satisfy the condition (12).

  According to the first aspect of the present invention, it is possible to configure an engine that can accurately control a multistage variable system supercharging system in which a high pressure supercharger and a low pressure supercharger are arranged in series.

  According to claim 2, when the ECU (60) does not satisfy the first condition (11) or the second condition (12), the current high-pressure turbo rotational speed (Nta_hp) is determined by the multistage variable system supercharging. It is determined that the system (20) is not the turbocharger speed of the high-pressure turbocharger that operates most efficiently, or the boost pressure (Bpa) is not the boost pressure that optimizes the combustion state of the engine (100). The ECU (60) adjusts the vane opening of the movable vane (25) until the first condition (11) is satisfied, and then the ECU (60) satisfies the second condition (12). By controlling to adjust the vane opening degree of the movable vane (25), the multistage variable system supercharging system can be accurately controlled, and the combustion state of the engine (100) is controlled to be optimum. Can do it.

1 is a configuration diagram showing an overall configuration of an engine according to Embodiment 1 of the present invention. The flowchart which similarly shows the flow of supercharger control. The flowchart which similarly shows the flow of another supercharger control. The block diagram which shows the whole structure of the engine which concerns on Embodiment 2 of this invention. The flowchart which similarly shows the flow of supercharger control. The flowchart which similarly shows the flow of another supercharger control. The block diagram which shows the whole structure of the engine which concerns on Embodiment 3 of this invention.

  Next, embodiments of the invention will be described.

  FIG. 1 is a block diagram showing the overall configuration of an engine according to Embodiment 1 as an embodiment, FIG. 2 is a flow diagram showing a flow of supercharger control, and FIG. 3 is a turbocharger control as a configuration cold. It is a flowchart which shows this flow. FIG. 4 is a block diagram showing the overall configuration of the engine according to configuration form 1, and FIG. 5 is a flowchart showing the flow of the supercharger control. FIG. 6 is a flowchart showing another supercharger control flow. FIG. 7 is a configuration diagram showing the overall configuration of the engine according to Configuration Mode 2. With reference to FIG. 1, a configuration of an engine 100 that is the first embodiment as a configuration example will be described. The engine 100 is a direct injection 6-cylinder diesel engine, and includes an intake manifold 12 to which an intake path 2 is connected, an exhaust manifold 13 to which an exhaust path 3 is connected, and fuel accumulated in a common rail to each cylinder by an injector. And a common rail fuel injection device (hereinafter referred to as a fuel injection device) 15 for injection.

  The engine 100 includes a supercharging system 20. The supercharging system 20 includes a high pressure supercharger composed of a high pressure compressor 21 and a high pressure turbo 22 and a low pressure supercharger composed of a low pressure compressor 31 and a low pressure turbo 32 arranged in series.

  The high-pressure supercharger is a supercharger that includes variable capacity means. The variable capacity means adjusts the vane opening degree of the movable vane 25 provided on the upstream side of the high-pressure turbo 22, adjusts the exhaust flow rate passing through the high-pressure supercharger, and controls the capacity of the high-pressure supercharger, that is, the charging efficiency. It is a means to adjust. In the following, a supercharging system in which two superchargers are arranged in series and at least one of the superchargers is provided with variable capacity means as in the configuration example will be described. Defined as the supply system.

  The intake path 2 passes through the intake manifold 12 from the upstream side (outside air side), the intercooler 33 that cools the air supercharged by the low pressure compressor 31, the high pressure compressor 21, and the high pressure compressor 21. And an intercooler 23 for cooling the supplied air.

  The exhaust path 3 is a high-pressure turbo 22, a bypass path 4 that short-circuits the high-pressure turbo 22, and a bypass flow rate adjusting unit that adjusts the bypass flow rate of the bypass path 4 from the exhaust manifold 13 toward the downstream side (outside air side). A bypass valve 24 and a low-pressure turbo 32 are provided.

  An engine control unit (hereinafter referred to as ECU) 60 as a control means includes a high pressure turbo sensor 61 provided in the high pressure compressor 21 via an amplifier 65, a boost sensor 62 provided in the intake manifold 12, a bypass valve 24, and fuel injection. The apparatus 15 and the movable vane 25 are connected to each other. Hereinafter, the adjustment of the vane opening of the movable vane 25 and the adjustment of the opening of the bypass valve 24 by the ECU 60 are defined as supercharger control.

  The supercharger control of the engine 100 will be described with reference to FIG. As a control means, the ECU 60 controls the high-pressure supercharger speed at which the high-pressure supercharger operates most efficiently and the supercharging pressure that optimizes the combustion state of the engine 100 when the engine 100 is at a low speed and a low load. And has a function of adjusting the vane opening of the movable vane 25 so as to become. First, the ECU 60 calculates the target high-pressure turbo rotational speed ωctrg_hp and the target boost pressure Bpatrg (S110). The target high-pressure turbo speed ωctrg_hp is a map stored in the ECU 60 in advance based on the command injection amount, the engine speed, and the boost pressure Bpa as the supercharger speed that operates most efficiently for the high-pressure supercharger. (Not shown). The target boost pressure Bpatrg is a map (not shown) stored in advance in the ECU 60 as a supercharging pressure that optimizes the combustion state of the engine 100 based on the command injection amount, the engine speed, and the high-pressure turbo speed Nta_hp. Is calculated from

  As a first condition (11), the ECU 60 determines whether the absolute value of the difference between the high-pressure turbo rotation speed Nta_hp detected by the high-pressure turbo sensor 61 and the target high-pressure turbo rotation speed ωctrg_hp is smaller than a first predetermined value α11. As a second condition (12), it is determined whether or not the absolute value of the difference between the boost pressure Bpa detected by the boost sensor 62 and the target boost pressure Bpatrg is smaller than a second predetermined value α12 (S120).

  When the ECU 60 satisfies the first condition (11) and the second condition (12) in S120, the high pressure turbo rotation speed Nta_hp is currently set to the high pressure supercharger at which the supercharging system 20 operates most efficiently. And the boost pressure Bpa is determined to be a supercharging pressure that optimizes the combustion state of the engine 100.

  On the other hand, if the ECU 60 does not satisfy the first condition (11) or the second condition (12) in S120, the high-pressure turbo rotational speed Nta_hp is currently set to a high-pressure excess value at which the supercharging system 20 operates most efficiently. It is determined that it is not the supercharger rotation speed of the charger, or the boost pressure Bpa is not a boost pressure that optimizes the combustion state of the engine 100.

  Therefore, the ECU 60 adjusts the vane opening of the movable vane 25 until the first condition (11) is satisfied (S140). Next, the ECU 60 adjusts the vane opening degree of the movable vane 25 until the second condition (12) is satisfied (S150).

  With reference to FIG. 3, another supercharger control of the engine 100 will be described. As a control means, the ECU 60 controls the high-pressure supercharger speed at which the high-pressure supercharger operates most efficiently when the engine speed and load of the engine 100 increase, and the supercharging pressure that optimizes the combustion state of the engine 100. The function of adjusting the opening of the high-pressure bypass valve 24 is as follows. The ECU 60 calculates the target high-pressure turbo rotational speed ωctrg_hp and the target boost pressure Bpatrg (S210). The target high-pressure turbo speed ωctrg_hp is obtained from a map stored in advance in the ECU 60 based on the command injection amount, the engine speed, and the boost pressure Bpa as the supercharger speed that operates most efficiently for the high-pressure supercharger. Calculated. The target boost pressure Bpatrg is calculated from a map stored in advance in the ECU 60 as a supercharging pressure that optimizes the combustion state of the engine 100 based on the command injection amount, the engine speed, and the high-pressure turbo speed Nta_hp. .

  As a condition (13), the ECU 60 determines whether the absolute value of the difference between the high-pressure turbo rotation speed Nta_hp detected by the high-pressure turbo sensor 61 and the target high-pressure turbo rotation speed ωctrg_hp is smaller than a predetermined value α13. It is determined whether or not the absolute value of the difference between the boost pressure Bpa detected by the boost sensor 62 and the target boost pressure Bpatrg is smaller than a predetermined value α14 (S220).

  When the ECU 60 satisfies the condition (13) and the condition (14) in S220, the high-pressure turbo rotation speed Nta_hp is currently set to the supercharger rotation speed of the high-pressure supercharger in which the supercharging system 20 operates most efficiently. Thus, boost pressure Bpa is determined to be a supercharging pressure that optimizes the combustion state of engine 100.

  On the other hand, if the ECU 60 does not satisfy the condition (13) or the condition (14) in S220, the high-pressure turbo rotational speed Nta_hp is currently set to the supercharger of the high-pressure supercharger in which the supercharging system 20 operates most efficiently. It is determined that the engine speed is not the engine speed or the boost pressure Bpa is not the boost pressure that optimizes the combustion state of the engine 100.

  Therefore, the ECU 60 adjusts the opening degree of the bypass valve 24 until the condition (13) is satisfied (S240). Next, the ECU 60 adjusts the opening degree of the bypass valve 24 until the condition (14) is satisfied (S250).

  In this way, the opening degree of the bypass valve 24 is adjusted by adjusting the vane opening degree of the movable vane 25 using the high pressure turbo speed Nta_hp and the boost pressure Bpa as feedback values, and using the high pressure turbo speed Nta_hp and the boost pressure Bpa as feedback values. Therefore, the multistage variable supercharging system can be controlled with high accuracy. That is, since the high-pressure turbo rotation speed Nta_hp that is directly related to the operation of the high-pressure supercharger is used as a feedback value, the time lag in the supercharger control is reduced and the response delay between the intake system and the exhaust system (turbo lag) And the occurrence of overshoot and undershoot of the boost pressure Bpa can be extremely reduced. In addition, since the high-pressure turbo rotation speed Nta_hp, which is directly related to the operation of the high-pressure supercharger, is used as a feedback value, the control can be performed with high accuracy without considering the mechanical variation of the high-pressure supercharger.

  Moreover, each supercharger has the highest rotation speed as a threshold value. In the conventional supercharging system, since the maximum rotation speed is indirectly determined by the boost value or the fuel injection amount, there is an offset value that allows for a safety factor. Therefore, since the high-pressure turbo rotation speed Nta_hp, which is directly related to the operation of the high-pressure supercharger, can be detected, the offset value considering the safety factor is unnecessary and the turbocharger operates efficiently. it can. At the same time, a wastegate as a safety device or a bypass valve on the intake side can be eliminated as in the conventional supercharging system, and simplification and cost reduction can be achieved.

  Further, in the conventional variable nozzle turbo, overspin (overspeed) due to exhaust inertia has been a problem. Normally, in the supercharging system, the fuel injection amount is limited so as not to overspeed, so the supercharger cannot be operated efficiently with the maximum boost. Therefore, the high speed turbo rotation speed Nta_hp, which is directly related to the operation of the high pressure supercharger, is detected, and the rotational speed is reduced by decreasing the vane opening degree of the movable vane 25 or increasing the opening degree of the bypass valve 24. Can be prevented and the turbocharger can be operated efficiently.

  The configuration of the engine 200 according to the first embodiment of the present invention will be described with reference to FIG. The engine 200 is a direct-injection 6-cylinder diesel engine, and includes an intake manifold 12 to which an intake passage 2 is connected, an exhaust manifold 13 to which an exhaust passage 3 is connected, and fuel accumulated in a common rail to each cylinder by an injector. And a common rail fuel injection device (hereinafter referred to as a fuel injection device) 15 for injection.

  The engine 200 is provided with a supercharging system 70. The supercharging system 70 includes a high pressure supercharger composed of a high pressure compressor 21 and a high pressure turbo 22 and a low pressure supercharger composed of a low pressure compressor 31 and a low pressure turbo 32 arranged in series. As described above, the supercharging system 70 is defined as a multistage variable system supercharging system.

  The low-pressure supercharger is a supercharger provided with variable capacity means. The variable capacity means adjusts the vane opening degree of the movable vane 35 provided on the upstream side of the low-pressure turbo 32, adjusts the exhaust flow rate passing through the low-pressure supercharger, and controls the capacity of the low-pressure supercharger, that is, the charging efficiency. It is a means to adjust.

  Since the intake path 2 and the exhaust path 3 are the same as those of the engine 100 according to the first embodiment as the configuration example, the description thereof is omitted.

  An engine control unit (hereinafter referred to as ECU) 60 as a control means includes a low pressure turbo sensor 66 provided in the low pressure compressor 31 via an amplifier 65, a boost sensor 62 provided in the intake manifold 12, a bypass valve 24, and fuel injection. The apparatus 15 and the movable vane 35 are connected to each other. As described above, the adjustment of the vane opening of the movable vane 35 and the adjustment of the opening of the bypass valve 24 by the ECU 60 are defined as supercharger control.

  The supercharger control of the engine 200 will be described using FIG. The ECU 60 has a low-pressure supercharger speed at which the low-pressure supercharger operates most efficiently and a supercharging pressure that optimizes the combustion state of the engine 200 when the engine 200 has a low speed and a low load. And has a function of adjusting the vane opening degree of the movable vane 35. The ECU 60 calculates the target low-pressure turbo speed ωctrg_lp and the target boost pressure Bpatrg (S310). The target low-pressure turbo rotational speed ωctrg_lp is obtained from a map stored in advance in the ECU 60 based on the command injection amount, the engine rotational speed, and the boost pressure Bpa as the supercharger rotational speed that operates most efficiently for the low-pressure supercharger. Calculated. The target boost pressure Bpatrg is calculated as a supercharging pressure that optimizes the combustion state of the engine 200 from a map stored in the ECU 60 in advance based on the command injection amount, the engine speed, and the target low-pressure turbo speed ωctrg_lp. The

  The ECU 60 determines whether the absolute value of the difference between the low-pressure turbo rotational speed Nta_lp detected by the low-pressure turbo sensor 66 and the target low-pressure turbo rotational speed ωctrg_lp is smaller than a predetermined value α21 as the condition (21). It is determined whether or not the absolute value of the difference between the boost pressure Bpa detected by the boost sensor 62 and the target boost pressure Bpatrg is smaller than a predetermined value α22 (S320).

  If the ECU 60 satisfies the condition (21) and the condition (22) in S320, the low-pressure turbo rotational speed Nta_lp is currently set to the supercharger rotational speed of the low-pressure supercharger in which the supercharging system 70 operates most efficiently. The boost pressure Bpa is determined to be a supercharging pressure that optimizes the combustion state of the engine 200.

  On the other hand, if the ECU 60 does not satisfy the condition (21) or the condition (22) in S320, the low-pressure turbo rotation speed Nta_lp is currently set to the supercharger of the low-pressure supercharger in which the supercharging system 70 operates most efficiently. It is determined that the engine speed is not the engine speed or the boost pressure Bpa is not the supercharging pressure that optimizes the combustion state of the engine 200.

  Therefore, the ECU 60 adjusts the vane opening degree of the movable vane 35 until the condition (21) is satisfied (S340). Next, the ECU 60 adjusts the vane opening degree of the movable vane 35 until the condition (22) is satisfied (S350).

  Another supercharger control of the engine 200 will be described with reference to FIG. The ECU 60 bypasses the turbocharger so that the low-pressure supercharger operates most efficiently and the supercharging pressure that optimizes the combustion state of the engine 200 when the rotational speed and load of the engine 200 increase. It has a function of adjusting the opening degree of the valve 24. The ECU 60 calculates the target low-pressure turbo speed ωctrg_lp and the target boost pressure Bpatrg (S410). The target low-pressure turbo rotational speed ωctrg_lp is a map stored in the ECU 60 in advance based on the command injection amount, the engine rotational speed, and the boost pressure Bpa as the supercharger rotational speed that operates most efficiently for the low-pressure supercharger. Calculated. The target boost pressure Bpatrg is calculated as a supercharging pressure that optimizes the combustion state of the engine 200 from a map stored in the ECU 60 in advance based on the command injection amount, the engine speed, and the target low-pressure turbo speed ωctrg_lp. The

  The ECU 60 determines whether the absolute value of the difference between the low-pressure turbo rotational speed Nta_lp detected by the low-pressure turbo sensor 66 and the target low-pressure turbo rotational speed ωctrg_lp is smaller than a predetermined value α23 as the condition (23). It is determined whether or not the absolute value of the difference between the boost pressure Bpa detected by the boost sensor 62 and the target boost pressure Bpatrg is smaller than a predetermined value α24 (S420).

  If the ECU 60 satisfies the condition (23) and the condition (24) in S420, the low-pressure turbo rotation speed Nta_lp is currently set to the supercharger rotation speed of the low-pressure supercharger in which the supercharging system 70 operates most efficiently. Therefore, it is determined that the boost pressure Bpa is a supercharging pressure that optimizes the combustion state of the engine 200.

  On the other hand, if the ECU 60 does not satisfy the condition (23) or the condition (24) in S420, the low-pressure turbo rotational speed Nta_lp is currently set to the supercharger of the low-pressure supercharger in which the supercharging system 70 operates most efficiently. It is determined that the engine speed is not the engine speed or the boost pressure Bpa is not the supercharging pressure that optimizes the combustion state of the engine 200.

  Therefore, the ECU 60 adjusts the opening degree of the bypass valve 24 until the condition (23) is satisfied (S440). Next, the ECU 60 adjusts the opening degree of the bypass valve 24 until the condition (24) is satisfied (S450).

  In this way, the opening degree of the bypass valve 24 is adjusted by adjusting the vane opening degree of the movable vane 35 using the low pressure turbo speed Nta_lp and the boost pressure Bpa as feedback values, and using the boost pressure Bpa and the low pressure turbo speed Nta_lp as feedback values. Therefore, the multistage variable supercharging system can be controlled with high accuracy. Since other effects are the same as those of the engine 100 of the first embodiment as the configuration example, the description is omitted.

  With reference to FIG. 7, the configuration of engine 300 that is the second embodiment as a configuration example will be described. The engine 300 is a direct-injection 6-cylinder diesel engine, and includes an intake manifold 12 to which an intake path 2 is connected, an exhaust manifold 13 to which an exhaust path 3 is connected, and fuel accumulated in a common rail to each cylinder by an injector. And a common rail fuel injection device (hereinafter referred to as a fuel injection device) 15 for injection.

  The engine 300 includes a supercharging system 80. The supercharging system 80 includes a high pressure supercharger composed of the high pressure compressor 21 and the high pressure turbo 22 and a low pressure supercharger composed of the low pressure compressor 31 and the low pressure turbo 32 arranged in series.

  Here, the high pressure supercharger is a supercharger provided with variable capacity means. The variable capacity means adjusts the opening degree of the movable vane 25 provided on the upstream side of the high-pressure turbo 22, adjusts the exhaust flow rate passing through the high-pressure supercharger, and adjusts the capacity of the high-pressure supercharger, that is, the charging efficiency. Means. The low-pressure supercharger is a supercharger that includes variable capacity means. The variable capacity means adjusts the opening degree of the movable vane 35 provided on the upstream side of the low-pressure turbo 32, adjusts the exhaust flow rate passing through the low-pressure supercharger, and adjusts the capacity of the low-pressure supercharger, that is, the charging efficiency. Means.

  Since the intake path 2 and the exhaust path 3 are the same as those of the engine 100 according to the first embodiment as the configuration example, the description thereof is omitted.

  The EGR device 50 is a device that recirculates a part of the exhaust gas to the intake side as an EGR amount. Further, the EGR device 50 includes an EGR cooler 53 that cools exhaust gas from the exhaust manifold 13 toward the intake manifold 12 and an EGR that adjusts the EGR amount in the EGR path 5 that short-circuits the exhaust manifold 13 and the intake manifold 12. The valve 51 is connected.

  An engine control unit (hereinafter referred to as ECU) 60 as a control means includes a high-pressure turbo sensor 61 provided in the high-pressure compressor 21 via an amplifier 65, a low-pressure turbo sensor 66 provided in the low-pressure compressor 31 via an amplifier 65, and an intake air The boost sensor 62 provided in the manifold 12, the bypass valve 24, the fuel injection device 15, the EGR valve 51, the movable vane 25, and the movable vane 35 are connected to each other.

  Here, the EGR control of the engine 300 will be described. The ECU 60 has a function of adjusting the opening degree of the EGR valve 51 as a control means so that an appropriate EGR amount is recirculated to the intake side. Therefore, the ECU 60 has a function of calculating the current EGR amount as a control means. At this time, the ECU 60 compares the high-pressure supercharger speed and the low-pressure supercharger speed when the EGR valve 51 is fully closed with the current high-pressure supercharger speed and low-pressure supercharger speed. Thus, an accurate EGR amount can be calculated.

  In this manner, the EGR amount can be accurately calculated using the high-pressure supercharger rotation speed and the low-pressure supercharger rotation speed. As a result, the EGR valve 51 can be accurately adjusted using the calculated EGR amount as a feedback value.

  Furthermore, the supercharger control of the engine 300 will be described. The ECU 60 has a function of calculating the current bypass amount as a control means in order to adjust the bypass valve 24 so that the turbocharger rotation speed at which the supercharging system 80 operates most efficiently is achieved. At this time, the ECU 60 can calculate the current accurate bypass amount by using the difference between the high-pressure supercharger speed and the low-pressure supercharger speed. As a result, the bypass valve 24 can be accurately adjusted using the calculated bypass amount as a feedback value.

DESCRIPTION OF SYMBOLS 3 Exhaust path 4 Bypass path 12 Intake manifold 13 Exhaust manifold 15 Fuel injection device 20 Supercharging system 21 High pressure compressor 22 High pressure turbo 24 Bypass valve 25 Movable vane 31 Low pressure compressor 32 Low pressure turbo 35 Movable vane 50 EGR device 60 Engine Control Unit
61 High-pressure turbo sensor 62 Boost sensor 66 Low-pressure turbo sensor 70 Supercharging system 80 Supercharging system 100 Engine 200 Engine 300 Engine Bpa Boost pressure Bpatrg Target boost pressure Nta_hp High-pressure turbo speed ωctrg_hp Target high-pressure turbo speed Nta_lp Low-pressure turbo speed ωc Low pressure turbo speed

Claims (2)

A multistage variable turbocharger in which a high-pressure supercharger comprising a high-pressure compressor (21) and a high-pressure turbo (22) and a low-pressure supercharger comprising a low-pressure compressor (31) and a low-pressure turbo (32) are arranged in series. A system (20);
A boost sensor (62) for detecting boost pressure in the intake manifold (12);
A high-pressure turbo sensor (61) provided in the high-pressure compressor (21) for detecting the rotational speed of the high-pressure turbo (22);
A movable vane (25) for adjusting the capacity of the high-pressure turbo (22);
ECU (60) which is a control means which adjusts the opening of the movable vane (25),
Based on the boost pressure detected by the boost sensor (62) and the high-pressure turbo rotational speed detected by the high-pressure turbo sensor (61), the ECU (60) opens the vane opening of the movable vane (25). An engine characterized by adjusting. A multistage variable turbocharger in which a high-pressure supercharger comprising a high-pressure compressor (21) and a high-pressure turbo (22) and a low-pressure supercharger comprising a low-pressure compressor (31) and a low-pressure turbo (32) are arranged in series. A system (20);
A boost sensor (62) for detecting boost pressure in the intake manifold (12);
A high-pressure turbo sensor (61) provided in the high-pressure compressor (21) for detecting the rotational speed of the high-pressure turbo (22);
A movable vane (25) for adjusting the capacity of the high-pressure turbo (22);
ECU (60) which is a control means which adjusts the opening of the movable vane (25),
The ECU (60) determines the target high-pressure turbo rotational speed (ωctrg_hp) at which the high-pressure supercharger operates most efficiently and the combustion state of the engine (100) when the engine (100) has a low rotational speed and a low load. A target boost pressure (Bpatrg) as a boost pressure to be optimized is calculated from a map stored in advance in the ECU 60,
As the first condition (11), the ECU (60) determines the absolute value of the difference between the high-pressure turbo rotational speed (Nta_hp) detected by the high-pressure turbo sensor (61) and the target high-pressure turbo rotational speed (ωctrg_hp). Is less than the first predetermined value (α11),
The ECU (60) determines that the absolute value of the difference between the boost pressure (Bpa) detected by the boost sensor (62) and the target boost pressure (Bpatrg) is the second condition (12). Judge whether it is less than the predetermined value (α12),
When the ECU (60) satisfies the first condition (11) and the second condition (12), the current high-pressure turbo rotation speed (Nta_hp) is most efficient in the multistage variable turbocharging system (20). It is the supercharger rotation speed of the high-pressure supercharger that operates well, and the boost pressure (Bpa) is determined to be the supercharging pressure that optimizes the combustion state of the engine (100),
When the ECU (60) does not satisfy the first condition (11) or the second condition (12), the current high-pressure turbo rotation speed (Nta_hp) is most efficient when the multistage variable turbocharging system (20) is used. It is determined that it is not the supercharger speed of the high-pressure supercharger that operates well, or that the boost pressure (Bpa) is not the supercharging pressure that optimizes the combustion state of the engine (100)
The ECU (60) adjusts the vane opening of the movable vane (25) until the first condition (11) is satisfied,
Next, the ECU (60) adjusts the vane opening degree of the movable vane (25) until the second condition (12) is satisfied.

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