JP4432512B2 - Supercharger and supercharging method - Google Patents

Description

  The present invention relates to a supercharger and a supercharging method, and more particularly, to a turbocharger and a supercharging method that can branch a part of compressed air and add rotational power to a turbine on the downstream side of a compressor.

  Conventionally, in order to avoid surging, a turbocharger having a configuration capable of branching a part of the air compressed by the compressor using an air bypass is known (see, for example, Patent Document 1).

  The supercharger is used for a reciprocating engine or a rotary engine. For example, the turbocharger is driven to rotate by high-temperature and high-pressure exhaust gas emitted from a 4-cycle piston engine, and the compressor is rotated by this rotation. Compressed air obtained by the rotation of is supplied to the engine.

The compressed air is used for combustion of fuel in a cylinder of the engine, and the combustion discharges the high-temperature and high-pressure exhaust gas (combustion gas that rotates the turbine).
JP 2003-239755 A

  By the way, in the turbocharger using the conventional air bypass, the air bypass increases the amount of work of the compressor and decreases the rotation speed of the compressor. As a result, the pressure decreases and the flow rate decreases. There is a problem that the originally required amount of compressed air cannot be supplied to a four-cycle engine or the like in which the supercharger is installed at a pressure that is originally required.

For example, necessary 4 vehicle-cycle engine or the like is installed, when the normal required rapid acceleration that does not require, the 4-cycle engine, the compressed air pressure P ₁ shown in FIG. 2 by the flow rate Q ₁ In spite of this, in the supercharger rotating at the rotational speed N ₁ , surging occurs when only the flow rate Q ₁ smaller than “Q ₁ + Q ₂ ” is supplied.

That is, the supercharger which rotates at a rotational speed N ₁ in order to generate the pressure P ₁ (compressor), if trying to supply flow rate "Q _1" to the engine, the upper surging area (surge line SL1 Area).

Therefore, in order to avoid surging, a part of the air compressed by the compressor of the supercharger (air having a flow rate of “Q ₂ ”) is released by an air bypass, and the engine has a flow rate of “Q ₁ ”. If only air is supplied, the flow rate of the exhaust gas for rotationally driving the turbine of the supercharger decreases.

Then, the rotational speed of the turbocharger turbine or compressor is reduced from “N ₂ ” to “N ₁ ”, and compressed air having the pressure P ₁ required by the engine cannot be obtained.

The flow rate Q _{1 is} determined by using another supercharger having characteristics different from those of the supercharger, that is, by providing a small supercharger such that the surging line SL1 is further on the left side. the compressed air of pressure P ₁ which corresponds to can be considered a method of supplying to the engine.

  However, in the above method, when rapid acceleration is not performed, the other supercharger is used when moved to the right side of L3 shown in FIG. The pressure cannot be increased due to the choke phenomenon caused by increasing the flow rate. That is, it becomes impossible to cover the flow range necessary for the engine.

  The present invention has been made in view of the above problems, and in a supercharger used for a piston engine or a rotary engine or a supercharging method for a piston engine or a rotary engine, air having a pressure required by the engine is used. It is an object of the present invention to provide a supercharger or a supercharging method that can easily supply only a flow rate required by the engine.

The invention according to claim 1 is used in a piston engine or a rotary engine, and a turbine is rotated by high-temperature and high-pressure exhaust gas that has come out of the engine, and a compressor is rotated by rotation of the turbine. the compressed air obtained by rotating the supercharger supplied to the engine, compressed by the compressor, the compressed air branching means for branching a part of the compressed air supplied to the engine, the rotational force to the compressor and compressor rotational force applying device which applies, in accordance with the amount of compressed air branched by the compressed air branching means, that it has a control means for controlling so as to impart a rotational force by the compressor rotational force applying means Features.

According to a second aspect of the present invention, in the turbocharger according to the first aspect of the present invention, the turbocharger further comprises surging precursor detection means for detecting a surging precursor in the compressor, and the control means includes the surging precursor detection means. When a sign of surging is detected, control is performed so as to apply a rotational force by the compressor rotational force applying means according to the amount of compressed air branched by the compressed air branching means. And

According to a third aspect of the present invention, in the supercharger according to the first or second aspect, the compressed air branching unit includes a branch path branched from a path connecting the compressor and the engine to each other. a structure in which an amount capable of controlling the valve of the compressed air flowing through the branch path, downstream of the valve, or is open to the atmosphere, or are connected to the upstream side of the compressor, or the said engine and said turbine with each other and each other with or connected to a path connecting said compressor rotational force applying means includes a feature that it is constituted by an electric motor to rotationally drive the rotary shaft member which connects the said turbine and said compressor to each other To do.

According to a fourth aspect of the present invention, in the supercharging method for a piston engine or a rotary engine, a part of the compressed air compressed by the compressor used for the supercharging and supplied to the engine is surging the compressor. A compressed air branching stage that branches to prevent the compressor, and a compressor rotational force applying stage that applies a rotational force to the compressor, and is applied in the compressor rotational force applying stage according to the amount of the branched compressed air It is characterized by controlling the rotational force .

  According to the present invention, in a supercharger used for a piston engine or a rotary engine, or a supercharging method for a piston engine or a rotary engine, air of a pressure required by the engine is supplied only at a flow rate required by the engine. There is an effect that it is easy to supply.

  FIG. 1 is a diagram schematically illustrating a state in which a supercharger 1 according to an embodiment of the present invention is installed in an engine E1.

  The supercharger 1 includes a casing (not shown), a rotating shaft member 3 that rotates with respect to the casing through a fluid bearing (not shown), for example, inside the casing, and the rotating shaft member. 3 is provided with a centrifugal compressor 5 provided on the one end portion 3A side, and a centrifugal turbine 7 provided on the other end portion 3B side of the rotary shaft member 3.

  The supercharger 1 is used for a reciprocating engine or a rotary engine. For example, the turbine 7 is rotationally driven by a high-temperature and high-pressure exhaust gas G3 emitted from a 4-cycle piston engine E1, and the compressor 5 is rotationally driven by this rotation. The compressed air G1 obtained by the rotation of the compressor 5 is supplied to the engine E1.

  The compressed air G1 is used for the combustion of fuel in the cylinder of the engine E1, and the combustion discharges the high-temperature and high-pressure exhaust gas (combustion gas for rotating the turbine 7) G3. is there.

  A muffler Mr <b> 1 is provided on the downstream side of the turbine 7.

  The compressed air G1 is supplied from the compressor 5 to the engine E1 through the path 9 communicating with the intake port of the engine E1 from the outlet of the compressor 5, and the exhaust gas G3 is supplied to the engine E1. The exhaust gas from the engine E1 is supplied to the turbine 7 through a passage 11 communicating with the inlet of the turbine 7, and the exhaust gas supplied to the turbine 7 is supplied from the outlet of the turbine 7 to the muffler. The gas is supplied from the turbine 7 to the muffler Mr1 through a path 13 communicating with Mr1, and then discharged into the atmosphere.

  In addition, the supercharger 1 branches a part of the compressed air compressed by the compressor 5 and supplied to the engine E1 (branches so that a part of the compressed air is not supplied to the engine E1). A branching means 15 is provided, and a compressor rotational force applying means 17 for applying a rotational force to the compressor 5 is provided.

  Further, in the supercharger 1, a surging precursor detection unit 19 that detects a precursor of surging in the compressor 5 (a precursor of surging that occurs in the compressor 5), and a surging precursor is detected by the surging precursor detector 19. In this case, there is provided control means 21 for controlling the compressed air to be branched by the compressed air branching means 15 and to apply the rotational force by the compressor rotational force applying means 17.

  Here, as the surging precursor detection means 19, the pressure of the compressed air compressed by the compressor 5 of the supercharger 1 is detected by a pressure sensor 23, and the detected pressure and the compressor detected by a sensor (not shown). It is possible to employ a device that detects a sign of surging from a rotational speed of 5 and a map showing the characteristics of the compressor 5 stored in advance in a memory (not shown) provided in the control means 21.

  The surging precursor detection means 19 does not show fluctuations in the rotational speed of the compressor 5 with a predetermined period shorter than the fluctuation period of the rotational speed of the compressor 5 due to the pulsation of the pressure of the exhaust gas emitted from the engine E1. A sign of surging may be detected by detecting with a sensor (for example, a sensor provided in the compressor rotational force applying means 17).

  Further, the surging precursor detecting means 19 detects a surging precursor by detecting the fluctuation cycle of the pressure at the inlet of the compressor 5 or the fluctuation cycle of the pressure at the outlet of the compressor 5 with a sensor (not shown). You may do it.

  The compressed air branching means 15 includes a branch path 25 branched from a path 9 connecting the compressor 5 and the engine E1. Accordingly, in the portion where the branch path 25 is formed, the path through which the compressed air flows is formed in a “Y” shape, for example.

  The compressed air branching means 15 is provided with a valve 27 capable of controlling the amount of compressed air flowing through the branch path 25, and the downstream side of the valve 27 is connected to the compressor 5 via the path E. Connected upstream.

  The downstream side of the valve 27 may be opened to the atmosphere via a route D, or a route 11 connecting the engine E1 and the turbine 7 of the supercharger 1 to each other via a route F. Alternatively, the turbine 7 and the muffler Mr1 may be connected to a path 13 that is connected to each other via a path H.

The compressor rotational force applying means 17 includes, for example, a rotary shaft member 3 provided between the turbine 7 of the supercharger 1 and the compressor 5 and connecting the turbine 7 and the compressor 5 to each other. It is comprised by the electric motor 29 used as rotation drive .

  For example, when the surging sign detection means 19 detects a surging sign, the control means 21 uses the compressed air branching means 15 to compress a part of the compressed air compressed by the compressor 5 and supplied to the engine E1. In addition to branching, in order to maintain the rotational speed of the compressor 5 almost as it is, the rotational force is applied by the compressor rotational force applying means 17.

  Here, the flow rate of the compressed air to be branched is set to an amount capable of supplying the necessary amount of compressed air having the pressure required by the engine E1 and avoiding the surging of the compressor 5.

  FIG. 2 is a diagram illustrating the characteristics of the supercharger 1, in which the horizontal axis indicates the flow rate of the compressed air, and the vertical axis indicates the pressure of the compressed air.

Referring to FIG. 2, the rotational speed of the compressor 5 is “N ₂ ”, the flow rate of the compressed air coming out of the compressor 5 is “Q1 + Q ₂ ”, and the branching flow rate is “Q ₂ ”. When the flow rate supplied to the engine E1 is “Q ₁ ”, surging does not occur in the compressor 5 as long as the flow rate of “Q ₁ + Q ₂ ” flows. “P ₁ ” is the pressure of compressed air required by the engine E1.

The flow rate of “Q ₁ + Q ₂ ” is a flow rate in the vicinity of the surging line SL1 at the rotation speed N ₂ , and the compressor 5 generally operates near the surging line SL1 (for each rotation speed). Driving at a flow rate near surging line SL1) is more efficient than operating in a region away from surging line SL1.

  Next, the operation of the supercharger 1 will be described.

First, as shown in FIG. 2, which performs vehicle is gradual acceleration the engine E1 is mounted, the compressor 5 is rotated at a rotational speed N _2, pressure compressed air "P _1", " It is assumed that only the flow rate of “Q ₁ + Q ₂ ” is supplied to the engine E1.

Subsequently, when the vehicle on which the engine E1 is mounted performs rapid acceleration, if the flow rate required by the engine E1 is “Q ₁ ”, surging occurs in the compressor 5. Before the occurrence of this, the surging precursor detecting means 19 detects a surging precursor, and the compressed air branching means 15 branches a part of the compressed air under the control of the control means 21 based on the detection result. That is, the compressed air having a flow rate of “Q ₂ ” is branched, and the compressed air having a flow rate of “Q ₁ ” is supplied to the engine E1. The flow rate of the compressor 5 remains “Q ₁ + Q ₂ ”.

  The flow of the exhaust gas G3 decreases due to the branching of the compressed air, and the rotational driving force of the compressor by the turbine 7 is insufficient. The shortage is compensated by the electric motor 29 under the control of the control means 21, and the compressor 5 prevents the rotation speed from decreasing.

  Here, the rotational driving force applied by the electric motor 29 will be described.

Assuming that the absorption power of the compressor 5 is “W _C ” (unit is J / s), this “W _C ” is “W _C = ρ _C · (Q ₁ + Q ₂ ) · C _PC · (TC ₂ −TC ₁ ) "(Formula f1).

Here, “ρ _C ” (unit: kg / m ³ ) is the density of compressed air, “C _PC ” (unit: J / kg K (Kelvin)) is the constant pressure specific heat of compressed air, and “TC ₂ "(Unit: K (Kelvin)) is the air temperature at the outlet of the compressor 5, and" _TC1 "(unit: K (Kelvin)) is the air temperature at the inlet of the compressor 5.

On the other hand, if the generated power of the turbine 7 is “W _t ” (unit is J / s), this “W _t ” is “W _t = (when the compressed air is not branched by the compressed air branching means 15”. _{ρ t · (Q 1 + Q} 2) + Mf) · C Pt · (T t1 -T t2) "(represented by formula f2).

Here, “ρ _t ” (unit: kg / m ³ ) is the density of the turbine gas, “Mf” (unit: kg / s) is the flow rate of the fuel supplied by the engine E1, and “C _Pt ”. (Unit: J / kgK (Kelvin)) is the constant pressure specific heat of the turbine gas, “T _t1 ” (unit: K (Kelvin)) is the gas temperature at the inlet of the turbine 7, and “T _t2 ” (unit: K (Kelvin) is the gas temperature at the inlet of the turbine 7.

Here, if “W _loss ” (unit: J / s) is the loss power of the turbocharger 1, “W _t = W _C + W _loss ” (equation f3) must be satisfied in the turbocharger 1. Don't be.

However, in the formula f2, when the compressed air is branched, the flow rate of “Q ₂ ” does not flow to the turbine 7, so that the rotational driving force by the turbine 7 is insufficient and the rotational speed of the compressor 5 is insufficient. become.

  Therefore, in order to make up for the shortage of the rotational driving force and prevent a decrease in the rotational speed of the compressor 5, the electric motor 29 applies a rotational driving force Wm (unit: J / s) to the compressor 5.

  According to the supercharger 1, a part of the compressed air compressed by the compressor 5 and supplied to the engine E1 is branched, and the rotational force of the turbine 7 which is insufficient due to this branching is compensated by the compressor rotational force applying means 17, The engine E1 needs compressed air at a pressure required by the engine E1 without causing surging in the compressor 5 and without reducing the pressure of the compressed air supplied to the engine E1. It becomes easy to supply only the flow rate.

  Since the surging of the compressor 5 occurs in a region where the pressure is high and the flow rate is low, if a part of the air compressed by the compressor 5 is branched as described above, a low flow rate of air is generated on the high pressure side. In other words, it is possible to supply the engine E1 with compressed air having a pressure and a flow rate in a surging generation region in a situation where no surging prevention device is present.

  When the engine E1 vehicle requires a sudden acceleration that is not normally required, or when the engine E1 vehicle performs a normal moderate acceleration, an appropriate pressure is determined according to the operating state of the engine E1. Compressed air can be supplied to the engine E1 at an appropriate flow rate, and the engine E1 can be operated efficiently.

  In addition, according to the supercharger 1, a sign of surging in the compressor 5 is detected, and the compressed air branching means 15 and the compressor rotational force applying means 17 are controlled according to the detected result. While operating the supercharger 1 in the vicinity of the surging line SL1, and thus operating the supercharger 1 efficiently, the compressed air having an appropriate pressure is supplied at an appropriate flow rate according to the operating state of the engine E1. Only to the engine E1.

  Moreover, according to the supercharger 1, since the branched compressed air is returned to the compressor 5, it is possible to prevent the compressed and heated air from being discharged directly to the engine room.

  Further, since the branched compressed air is exhausted into the paths 11 and 13 of the exhaust gas (exhaust gas exhausted from the engine E1) on the downstream side of the turbine 7, such as immediately before the muffler Mr1, the temperature rises. It is possible to prevent the discharged air from being directly discharged into the engine room, and to reduce the temperature rise of the compressed air at the outlet of the compressor 5 than when returning the branched compressed air to the compressor 5. In addition, it is possible to reduce the necessity of separately providing a cooling device for compressed air on the downstream side of the compressor 5 (path 9 between the compressor 5 and the engine E1).

  Further, since the electric motor 29 having the rotary shaft member 3 as the rotational drive shaft is adopted as the compressor rotational force applying means 17, the configuration of the compressor rotational force applying means 17 can be simplified and the responsiveness can be improved. It is possible to apply a rotational driving force to the compressor 5 in a good state, and it is possible to cope with fluctuations in the fast state of the engine E1 and the supercharger 1.

It is a figure which shows the outline of the state in which the supercharger which concerns on embodiment of this invention is installed in the engine. It is a figure which shows the characteristic of a supercharger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supercharger 5 Compressor 7 Turbine 15 Compressed air branching means 17 Rotating force giving means 19 Surging precursor detection means 21 Control means

Claims (4)

Used in a piston engine or a rotary engine , the turbine is rotated by high-temperature and high-pressure exhaust gas emitted from the engine, the compressor is rotated by the rotation of the turbine, and the compressed air obtained by the rotation of the compressor is In the supercharger that supplies the engine ,
Is compressed by the compressor, the compressed air branching means for branching a part of the compressed air supplied to the engine,
Compressor rotational force applying means for applying rotational force to the compressor ;
Control means for controlling to apply a rotational force by the compressor rotational force applying means according to the amount of compressed air branched by the compressed air branching means;
A turbocharger characterized by comprising: The turbocharger according to claim 1, wherein
Surging sign detection means for detecting a sign of surging in the compressor ,
When the surging precursor is detected by the surging precursor detecting unit, the control unit applies the rotational force by the compressor rotational force applying unit according to the amount of compressed air branched by the compressed air branching unit. A supercharger characterized by being controlled to In the supercharger according to claim 1 or 2,
The compressed air branching means includes a branch path branched from a path connecting the compressor and the engine to each other, and is provided with a valve capable of controlling the amount of compressed air flowing through the branch path. side is, or open to the atmosphere, or are connected to the upstream side of the compressor, or each other in the engine and the said turbine or connected to a path connecting to each other,
The compressor rotational force applying means, turbocharger, characterized in that it is constituted by an electric motor to rotationally drive the rotary shaft member which connects the said turbine and the compressor to each other. In a supercharging method for a piston engine or a rotary engine,
A compressed air branching stage which is compressed by the compressor used for the supercharging and branches a part of the compressed air supplied to the engine to prevent surging of the compressor ;
A compressor torque applying step for applying torque to the compressor ;
And controlling the rotational force applied in the compressor rotational force application step according to the amount of the branched compressed air.

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