JP2016020672A - engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine such that a surging state of a supercharger can be detected in advance.SOLUTION: An engine includes: a high-pressure supercharger 60; a supercharger rotation speed sensor 55 which detects a supercharger rotation speed Nt of the high-pressure supercharger 60; and an ECU 50 which predicts that the high-pressure supercharger 60 is to enter a surging state. The ECU 50 predicts that the high-pressure supercharger 60 is to enter the surging state when a supercharger rotation speed variation rate RNt of the supercharger rotation speed Nt of the high-pressure supercharger 60 is equal to or larger than a surging occurrence variation rate RNt1. Here, the supercharger rotation speed variation rate RNt is smaller as the supercharger rotation speed Nt is larger.SELECTED DRAWING: Figure 1

Description

  The present invention relates to engine technology.

  Conventionally, an engine equipped with a supercharger has been publicly known. A surging phenomenon is known as a phenomenon unique to a supercharger. The surging phenomenon is a phenomenon in which the turbocharger does not function normally due to the stall of the compressor in the supercharger, the back-stage compressed air flowing backward toward the front stage, or the like.

  For example, Patent Document 1 discloses an engine that predicts the occurrence of surging from the discharge pressure and suction pressure of a compressor and prevents the occurrence of surging. However, since the engine disclosed in Patent Document 1 uses a pressure sensor with poor responsiveness in predicting the occurrence of surging, the occurrence of surging can be detected only after the occurrence of surging.

JP 2006-266216 A

  The problem to be solved by the present invention is to provide an engine that can detect a surging state of a supercharger in advance.

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

  That is, in claim 1, it comprises a supercharger, a supercharger rotation speed detection means for detecting the rotation speed of the supercharger, and a control means for predicting that the supercharger is in a surging state, The control means predicts that the supercharger enters a surging state if the fluctuation rate of the rotation speed of the supercharger is equal to or greater than a predetermined fluctuation rate.

  According to a second aspect of the present invention, in the engine according to the first aspect, the predetermined fluctuation rate decreases as the rotational speed of the supercharger increases.

  According to the engine of the present invention, the surging state of the supercharger can be detected in advance.

The block diagram which shows the structure of an engine. The graph showing a supercharger rotation speed map. The graph figure showing a surging generation | occurrence | production fluctuation rate map. The graph figure showing another surging generation | occurrence | production fluctuation rate map. The flowchart which shows the flow of surging prediction control.

The configuration of the engine 100 will be described with reference to FIG.
In addition, in FIG. 1, the structure of the engine 100 is typically represented with the block diagram. Moreover, the broken line of FIG. 1 represents the electric signal line.

  The engine 100 is an embodiment according to the engine of the present invention. The engine 100 includes an air supply path 10, an exhaust path 20, an engine body 30, a high-pressure supercharger 60, a low-pressure supercharger 70, and an engine control unit (hereinafter referred to as ECU) 50 as control means. I have.

  The engine 100 of the present embodiment is a direct injection 6-cylinder diesel engine equipped with a two-stage supercharger. The engine of the present invention is configured as a direct injection 6-cylinder diesel engine, but is not limited thereto. The engine of the present invention may be a direct injection type four-cylinder engine, a V-type engine, or a sub-chamber engine.

  The air supply path 10 is a path for supplying air to the engine body 30. The air supply manifold 11, the intercoolers 12 and 13, the high pressure compressor 61, the low pressure compressor 71, the air cleaner 14, Is connected.

  The air supply manifold 11, the intercoolers 12 and 13, the high pressure compressor 61, the low pressure compressor 71 and the air cleaner 14 are directed from the outside toward the engine body 30. The air supply manifolds 11 are arranged in this order and are connected by an air supply pipe.

  The air supply manifold 11 is a manifold for introducing air into the cylinders 31 of the engine body 30. The intercooler 12 is a heat exchanger that cools air whose temperature has been increased by compression of the high-pressure compressor 61 and the low-pressure compressor 71. The intercooler 13 is a heat exchanger that cools air whose temperature has been increased by compression of the low-pressure compressor 71.

  The high-pressure compressor 61 is a component of the high-pressure supercharger 60 and will be described in detail later. The low-pressure compressor 71 is a component of the low-pressure supercharger 70 and will be described in detail later. The air cleaner 14 separates dust contained in the air supply with a filter medium such as a nonwoven fabric.

  The exhaust path 20 is a path for discharging air (exhaust gas) from the engine body 30 and is configured by connecting an exhaust manifold 21, a high-pressure turbine 62, and a low-pressure turbine 72 to an exhaust pipe. The exhaust manifold 21, the high pressure turbine 62, and the low pressure turbine 72 are arranged in the order of the exhaust manifold 21, the high pressure turbine 62, and the low pressure turbine 72 from the engine body 30 to the outside, and are connected by an exhaust pipe.

  The exhaust manifold 21 is a manifold that collects a plurality of exhaust pipes from the cylinders 31 of the engine body 30 into one. The high pressure turbine 62 is a component of the high pressure supercharger 60 and will be described in detail later. The low-pressure turbine 72 is a component of the low-pressure supercharger 70 and will be described in detail later.

  The engine body 30 includes a cylinder block (not shown), a cylinder head (not shown), and a fuel injection device 35. A plurality (six) of cylinders 31, 31... Are formed in the cylinder block. The fuel injection device 35 is a device that injects fuel accumulated in the common rail into each cylinder by an injector. The fuel injection device 35 is connected to the ECU 50.

  The high-pressure supercharger 60 is a device that raises the pressure of air taken in by the engine 100 to atmospheric pressure or higher, and is provided on the upstream side (as viewed from the exhaust path 20) of the two-stage supercharger. The high pressure supercharger 60 includes a high pressure compressor 61 and a high pressure turbine 62.

  The high-pressure turbine 62 is rotated at high speed using the internal energy of the exhaust gas discharged from the exhaust pipe. The high-pressure compressor 61 is driven by the high-pressure turbine 62 and sends compressed air from the supply pipe to the engine 100.

  The high-pressure supercharger 60 is provided with a supercharger rotational speed sensor 55 that detects the supercharger rotational speed Nt. The supercharger rotation speed sensor 55 is connected to the ECU 50.

  The low-pressure supercharger 70 is a device that raises the pressure of the air taken in by the engine 100 to atmospheric pressure or higher, and is provided on the downstream side (as viewed from the exhaust path 20) of the two-stage supercharger. The low pressure supercharger 70 includes a low pressure compressor 71 and a low pressure turbine 72.

  The low-pressure turbine 72 is rotated at high speed using the internal energy of the exhaust gas discharged from the exhaust pipe. The low-pressure compressor 71 is driven by the low-pressure turbine 72 and sends compressed air from the supply pipe to the engine 100.

  The bypass path 40 connects the upstream side and the downstream side of the high-pressure turbine 62. The bypass path 40 is provided with a bypass valve 22 (a waste gate valve) as a turbocharger speed increasing / decreasing means. The bypass valve 22 limits the flow rate of exhaust gas that passes through the bypass path 40.

  The ECU 50 comprehensively controls the operation of the engine 100. The ECU 50 is connected to an engine speed sensor 51, a load sensor 52, a supercharger speed sensor 55, and a fuel injection device 35.

  The engine speed sensor 51 detects the engine speed Ne of the engine 100. The load sensor 52 detects the load Ac of the engine 100 (accelerator opening in this embodiment).

  The ECU 50 has a function of predicting that the high-pressure supercharger 60 is in a state before falling into a surging state by a surging prediction control S100 described later. The ECU 50 stores a surging occurrence variation rate RNt1 described later in advance.

The supercharger rotation speed map Fnt will be described with reference to FIG.
In FIG. 2, the supercharger speed map Fnt is represented by a three-dimensional graph of the engine speed Ne, the load Ac, and the appropriate supercharger speed Ntm.

  The supercharger rotational speed map Fnt represents the correlation among the engine rotational speed Ne, the load Ac, and the appropriate supercharger rotational speed Ntm. The supercharger rotation speed map Fnt is stored in the ECU 50 in advance.

  The supercharger rotation speed map Fnt represents an appropriate supercharger rotation speed Ntm as an appropriate rotation speed of the high-pressure supercharger 60 at the engine rotation speed Ne and the load Ac. That is, the appropriate supercharger rotation speed Ntm is calculated from the engine rotation speed Ne, the load Ac, and the supercharger rotation speed map Fnt.

The surging occurrence variation rate map Frnt1 will be described with reference to FIG.
In FIG. 3, the surging occurrence fluctuation rate map Frnt1 is represented by a graph with the horizontal axis representing the turbocharger rotation speed Nt and the vertical axis representing the surging occurrence fluctuation rate RNt1.

  The surging occurrence fluctuation rate map Frnt1 represents the surging occurrence fluctuation rate RNt1 for each turbocharger rotation speed Nt. The surging occurrence variation rate map Frnt1 is stored in the ECU 50 in advance.

  The surging occurrence fluctuation rate RNt1 is the supercharger rotation speed fluctuation rate RNt immediately before the high-pressure supercharger 60 falls into the surging state. The surging occurrence fluctuation rate RNt1 is set such that the surging occurrence fluctuation rate RNt1 decreases as the supercharger rotation speed Nt increases.

Another surging occurrence fluctuation rate map Frnt2 will be described with reference to FIG.
In FIG. 4, the surging occurrence fluctuation rate map Frnt2 is represented by a graph with the horizontal axis representing the turbocharger rotation speed Nt and the vertical axis representing the surging occurrence fluctuation rate RNt2.

  The surging occurrence fluctuation rate map Frnt2 represents the surging occurrence fluctuation rate RNt2 for each turbocharger rotation speed Nt. The surging occurrence variation rate map Frnt2 is stored in the ECU 50 in advance.

  The surging occurrence fluctuation rate RNt2 is the supercharger rotation speed fluctuation rate RNt immediately before the high-pressure supercharger 60 falls into the surging state. The surging occurrence fluctuation rate RNt2 is set so that the surging occurrence fluctuation rate RNt2 is constant at any turbocharger rotational speed Nt.

The flow of the surging prediction control S100 will be described with reference to FIG.
In FIG. 5, the flow of the surging prediction control S100 is represented by a flowchart.

  Surging prediction control S100 is a state before the ECU 50 calculates the turbocharger rotational speed fluctuation rate RNt of the supercharger rotational speed Nt of the high-pressure supercharger 60, and the high-pressure supercharger 60 is in a surging state. It is control which predicts.

  In step S110, the ECU 50 acquires the engine speed Ne by the engine speed sensor 51, acquires the load Ac by the load sensor 52, and obtains an appropriate excess from the engine speed Ne, the load Ac, and the supercharger speed map Fnt. The feeder rotation speed Ntm is calculated.

  In step S120, the ECU 50 acquires the supercharger rotation speed Nt of the high-pressure supercharger 60 by the supercharger rotation speed sensor 55.

  In step S130, the ECU 50 calculates the turbocharger speed fluctuation rate RNt of the acquired supercharger speed Nt. Specifically, the ECU 50 calculates how much ratio is obtained from the acquired supercharger rotation speed Nt with respect to the appropriate supercharger rotation speed Ntm calculated in step S110.

  In step S140, the ECU 50 calculates the surging occurrence fluctuation rate RNt1 from the currently obtained supercharger rotation speed Nt and the surging occurrence fluctuation rate map Frnt1.

  In step S150, the ECU 50 checks whether or not the calculated supercharger rotation speed fluctuation rate RNt is greater than the calculated surging occurrence fluctuation rate RNt1. If the calculated turbocharger speed fluctuation rate RNt is greater than the calculated surging occurrence fluctuation rate RNt1, the ECU 50 proceeds to step S160.

  In step S160, the ECU 50 determines that the high-pressure supercharger 60 is in a state before falling into a surging state.

The effect of engine 100 will be described.
According to the engine 100, the surging state of the high-pressure supercharger 60 can be detected in advance.

  That is, according to the engine 100, the turbocharger rotational speed fluctuation rate RNt of the acquired supercharger rotational speed Nt is calculated, the surging occurrence fluctuation rate RNt1 is calculated, and the supercharger rotational speed fluctuation rate RNt is calculated as the surging occurrence fluctuation. When the rate is larger than RNt1, the surging state of the high-pressure supercharger 60 can be detected in advance by determining that the high-pressure supercharger 60 is in a state before falling into the surging state.

  In the present embodiment, the supercharger rotation speed sensor 55 is provided in the high-pressure supercharger 60 so that the surging state of the high-pressure supercharger 60 can be detected in advance. However, the present invention is not limited to this. For example, it is good also as a structure which can provide the supercharger rotation speed sensor in the low pressure supercharger 70, and can detect the surging state of the low pressure supercharger 70 in advance.

  In the present embodiment, the surging occurrence variation rate map Frnt1 is used in the surging prediction control S100. However, the present invention is not limited to this. For example, in the surging prediction control S100, a configuration using the surging occurrence variation rate map Frnt2 may be used.

DESCRIPTION OF SYMBOLS 10 Supply path 11 Supply manifold 12 Intercooler 13 Intercooler 14 Air cleaner 20 Exhaust path 21 Exhaust manifold 22 Bypass valve 30 Engine main body 31 Cylinder 35 Fuel injection device 40 Bypass path 50 ECU (control means)
55 Supercharger rotation speed sensor (supercharger rotation speed detection means)
60 High-pressure turbocharger (supercharger)
61 High-pressure compressor 62 High-pressure turbine 70 Low-pressure turbocharger 71 Low-pressure compressor 72 Low-pressure turbine

Claims (2)

A turbocharger,
Supercharger rotation speed detection means for detecting the rotation speed of the supercharger;
Control means for predicting that the supercharger is in a surging state;
With
The control means predicts that the supercharger is in a surging state if the fluctuation rate of the rotation speed of the supercharger is equal to or greater than a predetermined fluctuation rate.
engine. The engine according to claim 1,
The predetermined fluctuation rate decreases as the rotation speed of the supercharger increases.
engine.

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