JPS608424A - Control unit of supercharger - Google Patents

Abstract

PURPOSE:To perform the optimum control by controlling the turbine nozzle of a supercharger in response to the operational condition of an internal-combustion engine. CONSTITUTION:A variable-pitch nozzle 7 is provided upstream the blades of a turbine 5. An intake air pressure signal from an intake air pressure detector 14 via a line 15 and a load signal from a load detector 24 via a line 19 are inputted to a divider 13. A target value outputted from a constant setter 21 is subtracted from the output signal of the divider 13 at a subtractor 22, and the deviation signal is inputted to an amplifier 12. The amplified deviation signal is fed to a limiter 11. The limiter 11 sets the upper and lower limits in response to the variable range of the nozzle pitch. A signal from a control circuit 10 is inputted to a drive section 9 via a line 20 to drive a variable-pitch nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for controlling a turbine nozzle pitch of a supercharger according to the operating state of the internal combustion engine in an internal combustion engine equipped with a supercharger with a variable pitch nozzle.

In recent years, static pressure supercharging has come to be carried out as a matter of course from the standpoint of reducing fuel consumption and improving the output rate of internal combustion engines, and various studies are being conducted to improve the efficiency of superchargers. Generally, it is known that in order to reduce fuel consumption of an internal combustion engine, it is better to have a larger ratio between explosion pressure and supply air pressure. Since the explosion pressure is limited by the strength of the internal combustion engine and cannot be increased too much, increasing the ratio of the explosion pressure to the supply air pressure by rounding the supply air pressure is effective in improving fuel efficiency.

However, if the turbine nozzle of the supercharger is expanded too much in order to reduce the supply air pressure, there will be a delay in ensuring the performance of the internal combustion engine in a low load range.

In conventional superchargers, the pitch of the turbine nozzle, that is, the size of the orifice, is fixed, and there are some intermediate points such as deterioration of engine performance in the low load range and insufficient improvement in fuel efficiency in the normal use range. have. In order to solve these problems, a device has been proposed in which a cutoff valve is disposed in the turbine inlet gas passage to shut down one of the plurality of superchargers in a low load region. However, in such a device, the supercharger is started or stopped slowly so as not to cause a large change in the operation of the internal combustion engine, and therefore cannot follow sudden changes in load. Since this is a control of the operation η and stopping power of the turbocharger, it is not possible to perform fine control according to the load condition, and the effect of reducing fuel consumption is small. Furthermore, in an internal combustion engine with two superchargers, if the engine is stopped, surging will occur due to insufficient air volume, so such a control device is limited to large internal combustion engines with three or more superchargers. It has the disadvantage of being

Making the turbine nozzle area of the supercharger variable is effective in both reducing fuel consumption in the normal operating range of the internal combustion engine and ensuring performance in the low load range. The present invention can also be applied to internal combustion engines with one supercharger or two superchargers. In addition, by continuously controlling the turbine nozzle area, it is possible to smoothly follow changes in load, and the load state of the internal combustion engine can be controlled as finely as Vcg5.
Improvements in fuel efficiency can be expected over a wide driving range.

As a control device for a supercharger equipped with a variable pitch nozzle having a variable turbine nozzle area, a control device that detects the rotational speed of an internal combustion engine and operates the pitch of a turbine nozzle in accordance with the rotational speed can be considered. In addition, in the case of an internal combustion engine that powers a generator, the generator output, that is, the generated electric power KE, is used instead of the rotational speed.
Therefore, it is possible to consider a device that controls the pitch of the turbine nozzle. However, such devices control the nozzle pitch according to the relationship between the nozzle pitch and rotation speed (or power) that is predetermined through design calculations and factory operation, so the state of the internal combustion engine and the surrounding operating conditions are If it differs from that during factory operation, there is a drawback that optimum operation cannot be performed. In other words, even if the internal combustion engine is operated at the same rotational speed and load, the characteristics of the internal combustion engine will differ if ambient conditions such as air temperature, atmospheric pressure, and cooling seawater temperature change. Furthermore, as the supercharger and intercooler become dirty due to aging, and the conditions of the internal combustion engine change, the characteristics of the internal combustion engine change. If the internal combustion engine characteristics change in this way, the optimal relationship between nozzle pitch and rotation speed (or power) will also change.

Furthermore, when the number of operating cylinders changes due to range cylinder operation, etc., the characteristics of the internal combustion engine change significantly, and controlling the nozzle pitch by rotation speed (or electric power) makes it difficult to use a supercharger with a variable pitch nozzle. I can't get enough out of it.

An object of the present invention is to provide a supercharger control device that solves the above-mentioned technical problems and can perform optimal control according to the state of the internal combustion engine and the surrounding conditions of operation. be.

For a turbocharger with a fixed turbine nozzle pitch, a 2V is required to ensure performance in the low load range and achieve low fuel consumption in the normal operating range, so a supercharger that is compatible with the internal combustion engine is selected. It is desirable to do so. However, even with a fully adapted supercharger, problems such as an increase in heat load and deterioration of fuel efficiency occur when the load decreases. This occurs because the capacity of the supercharger is too large compared to the size of the debt, and if the capacity of the supercharger could be reduced in accordance with the reduction in load, this problem would not occur. A supercharger that is too large compared to the load of the internal combustion engine,
This will result in a significant drop in air supply pressure. The performance of an internal combustion engine is greatly affected by the air-fuel ratio, and if the air-fuel ratio is kept constant, the performance of the internal combustion engine can also be kept almost constant. On the other hand, the amount of air filled into the cylinder is controlled by the air supply pressure, and the amount of fuel supplied to the cylinder depends on the load. Therefore, if the ratio between the load and supply air pressure can be kept constant even when the internal combustion engine load changes, the air-fuel ratio in the normal operating range can be maintained even in the low load range, and performance deterioration in the low load range can be prevented. It can be prevented.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control system for a supercharger that prevents deterioration of an internal combustion engine by increasing supply air pressure by narrowing the nozzle pitch of a turbine in a low load range.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

A turbocharging a1, a turbine 5, and a blower 4 are coaxially connected, and air taken in from the atmosphere is compressed by the blower 4 and sent from an air outlet 2 to an internal combustion engine (not shown) +C. Exhaust gas that has been burned by the internal combustion engine is sent to gas population 3,
The turbine 5 is driven. Blades 6 are attached to the outer surface of the turbine 5 and convert the energy of the exhaust gas into rotational energy of the turbine 5. A variable pitch nozzle 7 is provided on the upstream side VC of the blade 6, and is configured so that the flow W and cross-sectional area of exhaust gas can be changed via a link 8.

The control circuit 10 has a built-in divider 8, and the divider 13 receives a supply pressure signal from the supply pressure detector 14 via a line 15, 24
A load signal is input from line 9 to line 9. The divider 13 calculates the ratio between the supply pressure signal and the load signal.

The target value RO output from the constant setter 21 is subtracted from the output signal from the divider 13 by a subtracter 22, and the deviation signal thereof is input to the amplifier 12. The amplified deviation signal is
The signal is sent to the limiter 11. Limiter 11 is Nos.

The upper and lower limits are set according to the variable range IC of Lupitz.

A control signal from the control circuit 10 is inputted to the drive unit 9Vc via a line 20, power amplified, and driven via the link 8 to the variable pitching unit 7.

The charge air pressure detector 14 is installed in an intake air manifold (not shown) of the internal combustion engine, and detects the pressure p in the manifold. The load detector 24 includes an indicator 16 (not shown) that detects the pressure inside the cylinder. Signals from the indicator 416 and the piston speedometer 17 are input to the arithmetic circuit 18, where the mean effective pressure pmi is calculated.

The calculation method is, for example...11) pmi=-; fp-cdt where S. piston stroke (cm) p; indicator output (kg/cm) C; piston quick injection (cm/s
), and the average effective pressure p· for each row 1- is calculated using an integrator and an appropriate coefficient unit. Pmi oil nl! You may use Ryu's well-known method for calculation. In the fifth embodiment of the shoe, the mean effective pressure pmi is outputted to the control circuit 10 via line 19 as a load signal.

FIG. 2 is a graph showing the relationship between the ratio p8/pmi of the supply pressure signal and the load signal and the nozzle pitch y. (a) and (b) in FIG. This is a case where the RO is changed. Due to the influence of wind and waves in the ambient conditions (1), &Cp and pmi may change temporarily, the control circuit 10 or the drive unit 9 may be provided with a slight time delay. The delay makes the control system 1 stable.

The operation of such an embodiment will be explained. Generally, when the load on the internal combustion engine decreases, the intake air temperature also decreases and the density of air increases, so the efficiency of filling air into the cylinder improves and the optimum p 2 /pmiO value also tends to decrease. Therefore, the control deviation increases in the negative direction, so the control signal from the control circuit 10 becomes smaller, and the nozzle pitch of the turbine 5 is narrowed. When the turbine nozzle pitch is narrowed, the air supply power ps increases, so p5/pm
H is held at the target I direct RO. The value of target @Ro differs slightly depending on the type of internal combustion engine, but for example, in the case of a large marine two-stroke internal combustion engine, it is about 0.2.

The embodiment shown in FIG. 1 is a so-called proportional control system in which the deviation signal and the Lully control signal are in a proportional relationship, so as the aperture of the turbine nozzle pitch increases, the individual control differences become smaller. Therefore, in a low load range with a large amount of throttling, ps”m
i becomes smaller than the target value RO, and the magnitude of the deviation depends on the gain of the amplifier 12. In this embodiment, ps/pm is applied along with the load.

It has the advantage of reducing the load and fully automatically correcting the influence of the load. Since there is a difference of several percent in the optimum ps/pmi value between a regular-use model and a low-negative model, this difference can be corrected by appropriately selecting the gain of the amplifier 120.

FIG. 3 is a block diagram of the control circuit 23 according to the embodiment of the present invention, and FIG. 4 is a graph showing the relationship between the nozzle pitch y and 9872 m1 in the embodiment shown in FIG. In this embodiment, the turbine nozzle pitch is directly controlled 1 according to the ratio of p8/pm+, and the constant setter 21 and subtracter 22 are omitted. This control circuit 23 is
Although the control function is inferior to that of the embodiment shown in the first figure, since the structure is simplified, it can be realized at low cost.

As another embodiment of the control circuit @10.28, a microcomputer may be used. If a microcomputer is used, the divider 13, compiler 22, and limiter II are as follows.
The program will change your mind.

In addition to the memory that stores the program, two separate analog/digital converters are required to read the supply pressure signal and load signal into the microcomputer, and a digital/analog converter is required to output the control signal. Become.

FIG. 5 is a flowchart of a program when the control circuit 10 is implemented by a microcomputer. When the power is turned on, step 100ff: is executed to perform initial reset of various registers and flags, and to initialize the control group. Next, the process moves to steps 1111 and 102, in which the load signal and the supply pressure signal are respectively read into a microcomputer (not shown) via an analog/digital converter (not shown). In step 109, the ratio r (=p, /pmH) between the supply pressure signal and the load signal is calculated, and in step ? In Q4, the control individual difference ε (=r-RO) is calculated. In step 105, the gain A is multiplied (y
=A, ε), and in step 106, it is limited by the limiter IIIC (ymin≦y≦yma)<). Next, the process moves to step 107, where it is converted into an analog quantity by a digital/analog converter (not shown), and is sent to the movable part 9 as a control signal.
is output to. Next, return to step 101 again and repeat the following steps one after another.

In the case of an internal combustion engine consisting of multiple cylinders, a representative cylinder may be selected and the load on that cylinder may be detected as shown in FIG.

If you measure the pmi of the gold cylinders and take the average, the internal combustion engine load will be more positive (N), and accurate control will be possible, but it will be expensive.

As another embodiment of the load detector, a torque meter may be provided on the output shaft of the internal combustion engine and a signal multiplied by the output Kll of this torque meter may be provided, but the torque meter is expensive.

When using a torque meter as a load detector, it is necessary to increase the target value RO by the mechanical efficiency of the internal combustion engine.

As yet another embodiment of the load detector, means for detecting the amount of fuel PF per stroke of the piston may be used. For example, in the case of a diesel engine, the injection amount per stroke can be detected by detecting the rack position of the fuel injection pump using, for example, a differential transformer type displacement meter. In addition, in pressure accumulation type injection, the injection amount can be calculated based on the fuel pressure and injection time.

According to this embodiment, a load detector can be realized at a relatively low cost compared to the pond embodiment.

In the case of an internal combustion engine that drives a generator, a wattmeter that detects the output of a constant electric machine may be used as a load detector. When using a wattmeter, it is necessary to consider the loss of the generator when determining the target value RO.

Further, as the load detector, an internal combustion engine intake counter or an internal combustion engine rotation speed meter may be used.

Also, when the load suddenly changes due to start-up or reversal, it is necessary to fix the turbine nozzle at a certain value to prevent the first-stroke system from becoming unstable.

As described above, according to the present invention, the difference between supply air pressure and internal combustion engine personnel?
il+' and calculate their ratio to obtain negative Wli
By detecting that the supply air pressure is too low compared to the load due to a decrease in the supply air pressure, the nozzle pitch of the turbocharger with a variable pitch nozzle is narrowed down to achieve supply air pressure commensurate with the load. This makes it possible to ensure internal combustion engine performance in the low fuel consumption range and low load range.

Furthermore, even if the conditions of the internal combustion engine change due to changes in ambient conditions such as air temperature, atmospheric pressure, and cooling seawater temperature, or if the supercharger or intercooler becomes dirty due to aging, the air supply will change in response to these changes. Detects pressure and can always achieve supply air pressure commensurate with the load.

[Brief explanation of drawings]

Figure i1 is a configuration diagram showing an embodiment of the present invention, and Figure 2 shows the ratio p8/pmi of the supply pressure signal to the load signal and the nozzle pitch y.
FIG. 3 is a block diagram of the control circuit 23 according to the embodiment of the present invention, and FIG. 4 is a graph showing the relationship between ps/pmi and nozzle pitch y in the embodiment shown in FIG. The graph shown in FIG. 5 is a flowchart when the control circuit 10 is implemented by a microcomputer. DESCRIPTION OF SYMBOLS 1...Supercharger, 9...Drive part, 10.28...Control circuit, 11...Limiter, 13...Divider, 14
...Air supply pressure detector, 16...Indicator, 18
...Arithmetic circuit, 22...Subtractor, 24...Load detector representative Patent attorney Kei Nishi Part Figure 1 Figure 2-1) s/pmi Figure 3 Weak Figure 4 ρslpmi Procedural amendment 1. Indication of the case Special application 58-116400 2. Name of the invention Turbocharger control device 3. Person making the amendment Relationship to the case Applicant address name (097) Kawasaki Heavy Industries Co., Ltd. Representative 4, Agent address 1-13-38 Nishihonmachi, Nishi-ku, Osaka Shinkoyaku Building International FAX GIII&GII (06)538-0
247 Commissioner of the Japan Patent Office 1. Indication of the case Patent application 1984-116400 2. Name of the invention Supercharger control device 3. Person making the amendment Relationship to the case Applicant address name (097) Representative of Kawasaki Heavy Industries, Ltd. 4. Address of the agent: 1-13-38 Nishihonmachi, Nishi-ku, Osaka City Shinko Kuyaku Pill 6. Subject of amendment: Detailed explanation of Funa's invention column 7. Contents of amendment (1) Specification, page 8, No. 2 In line 1, "deterioration of the internal combustion engine" should be corrected to "deterioration of engine performance." (2) Lines 16 to 19 of page 10 of the specification are corrected as follows. write down When the load decreases, p8 exceeds the rate of decrease.
ps/pmi" decreases. Therefore, the control deviation is (3) Correct the following on page 11, lines 6 to 7 of the specification. In the case of a two-stroke internal combustion engine, Generally, when the load on the internal combustion engine decreases, the intake air temperature also decreases and the air density increases, which improves the efficiency of filling air into the cylinder and reduces the optimum p5/pIT1i value. On the other hand, in the embodiment shown in the first diagram, the deviation signal and control No. 4.5 are proportional (4).The 13th line of page 11 of the specification is corrected as follows.It depends on the notation. In this example, p 5 / pmH or more with the load

Claims (1)

[Claims] +1) In an internal combustion engine equipped with a supercharger with a variable pitch nozzle, a drive unit that changes the nozzle pitch, a load detector that detects the load state of the internal combustion engine, and a pressure in an intake air manifold The air supply pressure detector that detects the
a control circuit 1 that responds to the load signal from the supply air pressure sensor and the supply air pressure signal from the supply air pressure detector force, calculates a ratio thereof, and sends a signal to the drive unit, and If the ratio is small, the nozzle pitch is narrowed, and if the ratio is large, the nozzle pitch is widened. . (2) The first control circuit calculates the difference between the ratio of the air supply pressure signal and the load signal and a predetermined constant value, and controls the nozzle pitch by the drive unit based on this difference. A supercharger control device according to claim 1, characterized in that: (3) A limiter is provided between the drive unit and the control circuit for limiting the magnitude of the restraining signal sent from the control circuit to a certain value or less. A control device for a supercharger according to item 1 or 2. (4) The load detector comprises an indicator that detects the cylinder pressure and an arithmetic circuit that calculates the average effective pressure from the output of the indicator. supercharger control device. (5) The supercharger constraint according to claim 1 (4) or 2 (2), wherein a torque meter for measuring the torque of the internal combustion engine is used as the load detector. (61fftl The supercharger control device according to claim 1 or 2, characterized in that an internal combustion engine tachometer is used as the output device.) 7) An internal combustion engine tachometer is used as the load detector. 2. A supercharger control device according to claim 1, which uses a wattmeter connected to the output of a chicken-breeding machine driven by an engine. (8) A braking device for a supercharger according to claim 1 or 2, characterized in that means for detecting the amount of fuel Fl per stroke is used as the load detector. (9) The supercharger control device according to claim 1 or 2, characterized in that an internal combustion engine intake airflow meter is used as the load detector.