JPH0129974B2 - - Google Patents

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 lowering 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 lower the charge air pressure, problems will arise in ensuring the performance of the internal combustion engine in a low load range.

Conventional superchargers have a fixed turbine nozzle pitch, or orifice size, and have problems such as deterioration of internal combustion engine performance in low load ranges and insufficient improvement in fuel efficiency in normal use ranges. are doing. In order to solve this problem, a device has been proposed in which a cutoff valve is disposed in the turbine inlet gas passage and one of the plurality of superchargers is stopped in a low load region. However, in such a device, the supercharger is operated 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. Further, since the control is based on whether the supercharger is operated or stopped, fine control according to the load condition cannot be performed, and the effect of reducing fuel consumption is small.
Furthermore, in an internal combustion engine with two superchargers,
If one turbocharger is stopped, surging will occur due to insufficient air volume, so this kind of control device will stop three turbochargers.
It has the disadvantage that it is limited to large internal combustion engines with more than 1000 yen.

By making the turbine nozzle area of the turbocharger variable,
It is effective in both reducing fuel consumption in the normal operating range of an internal combustion engine and ensuring performance in the low load range. And the supercharger is 1
It can also be applied to one or two internal combustion engines. Furthermore, by continuously controlling the turbine nozzle area, changes in load can be smoothly followed, fine-grained control can be performed according to the load condition of the internal combustion engine, and fuel efficiency can be expected to improve over a wide operating range.

As a control device for a pitch nozzle-equipped supercharger with a variable turbine nozzle area, a device that detects the rotational speed of an internal combustion engine and operates the pitch of a turbine nozzle according to the rotational speed can be considered. In the case of an internal combustion engine that drives a generator, a device may be considered that controls the pitch of the turbine nozzle in accordance with the generator output, that is, the generated power, instead of the rotational speed. 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 operating ambient conditions are determined at the time of design calculation and factory operation. If it differs from that during 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 rotation speed and the same load, the internal combustion engine characteristics will differ if ambient conditions such as air temperature, atmospheric pressure, and cooling seawater temperature change. Furthermore, if the supercharger or intercooler becomes dirty due to aging and the condition of the internal combustion engine changes, the characteristics of the internal combustion engine will change. If the internal combustion engine characteristics change in this way, the optimal relationship between nozzle pitch and rotational speed (or power) will also change.

Furthermore, when the number of operating cylinders changes due to cylinder reduction operation, etc., the internal combustion engine characteristics change significantly.
Controlling the nozzle pitch by rotational speed (or electric power) cannot fully bring out the significance of a supercharger with a variable pitch nozzle.

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

In conventional turbochargers with a fixed turbine nozzle pitch, it is necessary to achieve low fuel consumption in the normal operating range while ensuring performance in the low load range, so it is important to select a supercharger that is compatible with the internal combustion engine. desired. 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 load, and if the capacity of the supercharger could be reduced in accordance with the reduction in load, this problem would not occur. In fact, in an internal combustion engine equipped with a conventional supercharger with a fixed nozzle pitch, the rate of decrease in charge air pressure is greater than the rate of decrease in load.

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 the 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.

The present invention detects the load condition of the internal combustion engine and the supply air pressure, calculates the ratio of these, and sends a signal to the drive unit of the nozzle pitch in order to match this ratio to an optimal value that changes depending on the magnitude of the load. The object of the present invention is to provide a control device for a supercharger that outputs a supercharger according to the load of an internal combustion engine and ambient conditions.

The present invention provides a supercharger control device for an internal combustion engine equipped with a supercharger 1 with a variable pitch nozzle in which the pitch of a turbine inlet nozzle is variable, comprising: (a) a drive section 9 that changes the nozzle pitch; b) The load detector 24 includes (b1) an element 16 that detects the pressure inside the cylinder, (b1) a piston speed meter 17 that detects the piston speed, and (b3) the pressure detection element 16 and the piston speed meter 17. (c) a charge air pressure sensor for detecting the pressure in the intake air manifold; (d) A supply air temperature detector 13 that detects the temperature inside the intake air manifold, (e) A calculation circuit 18 of the load detector 24 that stores the target supply air pressure corresponding to each load in advance. (f) a memory circuit 21 for deriving a target supply air pressure corresponding to the average effective pressure pmi in response to an output representing a load that is an average effective pressure pmi from the memory circuit 21; (g) a correction circuit 26 that corrects the output using the output of the supply air temperature detector 13 to obtain an optimal target value of supply air pressure; (g) the output of the supply air pressure detector 14 and the correction circuit 26;
(h) In response to the output of the subtractor 22, the supply air pressure detected by the supply air pressure detector 14 is the supply air pressure from the correction circuit 26. to match the target value,
This is a control device for a supercharger characterized in that it includes means 12 for changing the nozzle pitch by means of a drive section 9.

FIG. 1 is a system diagram showing the basic configuration of the present invention.

In the supercharger 1, 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). Exhaust gas that has been burned by the internal combustion engine is sent to the gas inlet 3 and drives the turbine 5. Blades 6 are attached to the outer periphery of the turbine 5.
The energy of the exhaust gas is converted into the rotational energy of the turbine 5. A variable pitch nozzle 7 is provided on the upstream side of the blade 6 (ie, on the inlet side of the turbine 5), and is configured so that the cross-sectional area of the exhaust gas flow path can be changed via a link 8.

The control circuit 10 is configured to control each load of the internal combustion engine (in the present invention, the average effective pressure pmi for each stroke of the internal combustion engine).
A memory circuit 21 is built in which stores in advance a target value of the supply air pressure for the load (used as a value representing the load). This memory circuit 21 includes a load detector 2
A load signal is input from 4 through line 19. In the subtractor 22, the supply pressure signal _ps input from the supply pressure detector 14 via the line 15;
A comparison calculation is made with p _s ^ as the target value of the supply air pressure outputted from the memory circuit 21. The deviation signal from the subtracter 22 is input to the amplifier 12. The amplified deviation signal is sent to the limiter 11. The limiter 11 sets upper and lower limits according to the variable range of the nozzle pitch. A control signal from the control circuit 10 is input to the drive unit 9 via the line 20,
The power is amplified to drive the variable pitch nozzle 7 via the link 8.

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 _s in the manifold. The load detector 24 includes an indicator 16 (not shown) that detects the pressure inside the cylinder. The signals from the indicator 16 and the piston speedometer 17 are input to an arithmetic circuit 18, where the average effective pressure p _ni is calculated.

The calculation method is, for example, p _ni = 1/s∫p・cdt...(1) where s: Piston stroke (cm) p: Indicator output (Kg/cm ² ) c: Piston speed (cm/s) The average effective pressure p _ni for each stroke is calculated using an integrator and a suitable coefficient multiplier. Other known methods may be used to calculate p _ni . In this example, the average effective pressure p _ni is used as the load signal on line 1.
9 to the control circuit 10.

In this configuration, the target value p _s ^ of the optimal supply air pressure is determined in advance through a test run on land and stored in the memory circuit 21, and the nozzle pitch is controlled so that the supply air pressure becomes the optimal supply air pressure. do. In this case, the setpoint value p _s ^ changes depending on the mean effective pressure p _ni , for example as shown in FIG. 2. Since p _s ^ and p _ni may change temporarily due to the influence of wind and waves in the surrounding conditions, a slight time delay may be provided in the control circuit 10 or the drive unit 9. A time delay of appropriate size makes the control system stable.

The operation of this configuration will be explained. When the load on the internal combustion engine decreases, the load signal sent to the storage circuit 21 via the line 19 also decreases, so that the output p _s ^ of the storage circuit 21 also decreases.
On the other hand, since the supply pressure decreases by more than the rate of the load decrease, the supply pressure signal p _s sent to the subtractor 22 via line 15 falls below p _s ^. As a result,
Since the control deviation becomes smaller, the control signal from the control circuit 10 becomes smaller and the nozzle pitch of the turbine 5 is narrowed. When the nozzle pitch of the turbine 5 is narrowed, the air supply pressure increases and is maintained at the optimum air supply pressure target value p _s ^. If the load on the internal combustion engine increases, the operation is reversed to that described above, the nozzle bit is widened, and the charge air pressure is maintained at the optimal setpoint value p _s →. The value of the target value p _s ^ varies slightly depending on the type of internal combustion engine, but for example, in the case of a large two-stroke internal combustion engine for ships, it is approximately p _s /p _ni =0.2.

Another embodiment of the control circuit 10 may use a microcomputer 50 as shown in FIG. If the microcomputer 50 is employed, the limiter 11, subtracter 22, etc. can be replaced with programs. In addition to the memory circuit 51 that stores programs, an analog/digital converter 52 for reading supply air pressure signals, load signals, etc. into the microcomputer 50 and a digital/analog converter 53 for outputting control signals are separately provided. It becomes necessary. The signals via lines 15 and 19 are
Each is converted into a digital quantity by an analog/digital converter 52, and the microcomputer 5
Read to 0. The microcomputer 50 executes instructions according to a program stored in the storage circuit 51, converts the control output into an analog quantity using the digital/analog converter 53, and outputs the analog quantity.

FIG. 4 is a flowchart for explaining the operation of the configuration shown in FIG. When the power is turned on, step 100 is executed to initialize various registers and flags and initialize the control system. Next, in steps 101 and 102, the load signal and the supply pressure signal are respectively read into the microcomputer 50 via the analog/digital converter 52. In step 103, the target value p _s ^ is calculated, and in step 104, the control deviation ε (= p _s - p _s ^)
is calculated. In step 105, the gain A is multiplied (y=A・ε), and in step 106, it is limited by the limiter 11 (ymin≦y≦
ymax). Next, the process moves to step 107, where the digital/analog converter 53 converts the signal into an analog quantity and outputs it to the drive section 9 as a control signal. Next, return to step 101 again and repeat the following steps one after another.

FIG. 5 is a configuration diagram showing an embodiment of the present invention. In this embodiment, a supply air temperature signal is input from the supply air temperature detector 13 via a line 25 to a correction circuit 26 built into the control circuit 10. This correction circuit 26 performs a correction operation on the output from the storage circuit 21 and the supply air temperature signal, and outputs a target value p _s of the supply air pressure to the subtracter 22 .

If the ambient temperature changes or the blower or intercooler becomes dirty and the supply air temperature Ts changes, the density of the supply air changes and the optimal value of p _s ^ also changes. The correction method using Ts takes advantage of the fact that the amount of air filled into a cylinder is inversely proportional to (350 + Ts), for example, p _s ＾ = p _s ^* 350 + Ts / 350 + Ts ^* where Ts; supply air temperature (supply air temperature Detector 1
3 output) (℃) Ts ^* ; Supply air temperature in standard condition (℃) p _s ^* ; Optimal supply air pressure in standard condition (ata) p _s ^; Target value of supply air pressure after correction (ata) may be used as

As described above, according to the present invention, the target supply air pressure corresponding to the mean effective pressure pmi is derived from the memory circuit 21 as the load of the internal combustion engine, and this target supply air pressure is corrected based on the supply air temperature. , so that the deviation between the target value of the optimal supply air pressure obtained by correcting in this way and the actual supply air pressure detected by the supply air pressure detector 14 becomes zero, that is, the detected actual supply pressure is adjusted to zero. Since the nozzle pitch is changed so that the supply pressure matches the supply pressure target value from the correction circuit 26, the average effective pressure pmi, that is, the supply pressure commensurate with the load is realized. This makes it possible to reduce fuel consumption in the normal use range and ensure internal combustion engine performance in the low load range.

In addition, even if ambient conditions such as air temperature, atmospheric pressure, and cooling seawater temperature change, or if the condition of the internal combustion engine changes as the supercharger and intercooler become dirty due to aging, the internal combustion engine will change in response to these changes. The air supply pressure can be detected and the air supply pressure commensurate with the load can always be achieved.

Further, in the present invention, the supercharger has a configuration in which the pitch of the turbine inlet nozzle is variable. Therefore, by narrowing this turbine nozzle pitch, the resistance of the air path from the inlet of the blower 4 to the outlet of the turbine 5 is increased, and the supply air pressure is increased.
This makes it possible to increase the amount of air supercharged into the cylinder, that is, into the combustion chamber, thereby improving the performance of the internal combustion engine.

Furthermore, in the present invention, the optimum supply air pressure p _s ^ is corrected depending on the supply air temperature, which is as follows.
It is based on the fact that the amount of air stored in the cylinder depends not only on the supply air pressure, but also on its temperature. In this way, an optimum charge air pressure for the internal combustion engine can be achieved.

Thus, the present invention is based on the fact of internal combustion engine engineering and experimental/actual machine conditions that "the optimal charge air pressure depends on the load of the internal combustion engine, that is, the mean effective pressure PMI", and therefore, the above-mentioned As such, it is certain to improve the performance of the internal combustion engine.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the basic configuration of the present invention, FIG. 2 is a graph showing the relationship between the target value p^ ^s and the load signal _pni , and FIG. 3 is another embodiment of the control circuit 10. 4 is a flowchart for explaining the operation of the structure shown in FIG. 3, and FIG. 5 is a block diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Supercharger, 9...Drive part, 10...Control circuit, 1
DESCRIPTION OF SYMBOLS 1... Limiter, 13... Supply air temperature detector, 14... Supply air pressure detector, 21... Memory circuit, 22... Subtractor,
24...Load detector, 26...Correction circuit.

Claims (1)

[Scope of Claims] 1. A supercharger control device for an internal combustion engine equipped with a variable pitch nozzle supercharger 1 in which the pitch of a turbine inlet nozzle is variable, comprising: (a) a drive unit 9 for changing the nozzle pitch; (b) Load detector 24, (b1) Element 16 that detects pressure in the cylinder, (b2) Piston speed meter 17 that detects piston speed, (b3) Pressure detection element 16 and piston. (c) detecting the pressure in the intake air collecting pipe; (d) A supply air temperature detector 13 that detects the temperature inside the intake air manifold; (e) A target supply air pressure corresponding to each load is stored in advance and the load detector 24 (f) a memory circuit 21 for deriving a target air supply pressure corresponding to the average effective pressure pmi in response to the output representing the load, which is the average effective pressure pmi from the calculation circuit 18; (f) a target air supply pressure from the memory circuit 21; (g) a correction circuit 26 that corrects the output representing pressure using the output of the supply air temperature detector 13 to obtain an optimal target value of the supply air pressure; (g) the output of the supply air pressure detector 14; circuit 26
(h) In response to the output of the subtractor 22, the supply air pressure detected by the supply air pressure detector 14 is the supply air pressure from the correction circuit 26. to match the target value,
A control device for a supercharger, comprising means 12 for changing the nozzle pitch by means of a drive section 9.