JPS6045721A - Controller for supercharger - Google Patents

Abstract

PURPOSE:To save fuel cunsumption of an internal combustion engine by controlling a plurality of superchargers in common with one unit of a control circuit to improve the efficiency of the whole supercharger. CONSTITUTION:A divider 13 receives an intake pressure signal from an intake pressure detector 14 through a line 15 and a load signal from a load detector 24 through a line 19. The diveder 13 calculates the ratio of the intake pressure signal to the load signal. From the output signal of the divider 13 is subtracted a desired value generated from a constant setter 21 by subtractor 22 so that the deviation signal is sent to the input of an amplifier 12. The amplified deviation signal is sent to a limiter 11 which sets the upper and lower limits according to the variable range of nozzle pitch. The control signal of a control circuit 10 is supplied to the input of a drive section 9 through line 20 to drive a variable pitch nozzle 7 through a link 8.

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 plurality of superchargers with variable pitch nozzles.

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 frozen and expanded in order to lower the charge air pressure, a problem arises 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, resulting in problems such as deterioration of internal combustion engine performance in the low load range and insufficient improvement in fuel efficiency in the normal use range. There is.

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. In other words, in conventional turbochargers with a fixed turbine nozzle pitch, while ensuring performance in the low load range,
It is necessary to achieve low fuel consumption in the normal operating range, and it is desirable to select a supercharger that is compatible with the internal combustion engine. 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. A supercharger that is too large compared to the load of the internal combustion engine will result in a significant drop in charge air 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 nozzle pitch of the supercharger can be made variable and the nozzle pitch can be controlled to keep the ratio between the load and the supply air pressure constant even when the internal combustion engine load changes, the air-fuel ratio in the normal operating range can be kept at a low load. It can be maintained even in low load ranges, and performance deterioration in low load ranges can be prevented.

A control device that is provided with a detector that detects the operating state of the engine and that adjusts the supply air pressure by appropriately narrowing down the nozzle pitch of the turbine in accordance with the load satisfies the above purpose.

When one internal combustion engine is equipped with a plurality of superchargers with variable pitch nozzles and each supercharger is controlled individually, for example, one supercharger supplies combustion air in a fully open state, while the other A situation may occur where the supercharger does not supply combustion air and becomes completely closed.

Such a bias in the load on the supercharger reduces the efficiency of the entire supercharger, resulting in worsening of the fuel efficiency of the internal combustion engine.

An object of the present invention is to provide an inexpensive supercharger capable of improving the overall efficiency of the supercharger and improving the fuel efficiency of the internal combustion engine in an internal combustion engine equipped with a plurality of superchargers with variable pitch nozzles. The purpose of the present invention is to provide a control device for the following.

FIG. 1 is a configuration diagram showing an embodiment of the present invention. The internal combustion engine 30 has a plurality of cylinders 31 to 36, and each cylinder 31
36 are commonly connected to the intake air collecting pipe 37 and the exhaust gas collecting pipe 38. These collecting pipes 37 * 38
is equipped with a plurality (in this embodiment, two) of variable pitch nozzle-equipped superchargers 1a, lb. In the following description, the components with subscripts a and b are related to the superchargers 1a and lb, respectively, and the subscripts a and b are generally omitted. In the supercharger 1, a turbine 5 and a blower 4 are coaxially connected, and air sucked in from the atmosphere is compressed by the blower 4 and sent to a collecting pipe 37 from an air outlet 2a. Exhaust gas that has been combusted by the internal combustion engine 30 is transferred from the collecting pipe 38 to the gas population 3
and drives the turbine 5. Blades 6 are attached to the outer periphery of the turbine 5 and convert the energy of exhaust gas into rotational energy of the turbine 5. A variable pitch nozzle 7 is provided on the upstream side of the blade 6, 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 has a built-in divider 13, and the divider 13 receives a supply pressure signal from a supply pressure detector 14 via a line 15, and also receives a supply pressure signal from a load detector 24 via a line 19. A load signal is input through the terminal. Divider 13
Then, calculate 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 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 section 9 via the line 20, power amplified, and transmitted via the link 8.
The variable pitch nozzle 7 is driven.

The air supply pressure detector 14 is installed in an intake air collection pipe (not shown) of the internal combustion engine, and detects the pressure p3 inside the collection pipe. The load detector 24 includes an indicator 6 (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.sub.2 is calculated.

The l calculation method is, for example, pmi = -fp-cdt... (1) where S;
Viston stroke (cm) p: Indicator output (k
g/Cm2)C: Piston speed (cm/s), and the average effective pressure pm for each stroke is calculated using an integrator and a suitable coefficient unit. Other known methods may be used to calculate pm. In this embodiment, the mean effective pressure pmi is output as a load signal to the control circuit 10 via line 19.

FIG. 2 is a graph showing the relationship between the ratio ps/pmi of the supply pressure signal and the load signal and the nozzle pitch y.

(al, (b) in Figure 2 shows the case where the target value RO of the constant setter 21 is changed.P and pmi may fluctuate temporarily due to the influence of wind and waves in the surrounding conditions. , the control circuit 10 or the drive unit 9 may have a slight time delay.An appropriate time delay stabilizes the control system.

The operation of such a control device will be explained. In general, when the load on the internal combustion engine decreases, the intake air temperature also decreases and the density of the air increases, so the efficiency of filling air into the cylinders becomes better and the optimum p8/pmi 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 nozzle pitch of the turbine is narrowed, the supply air pressure p8 increases, so p,/prrli is equal to the target value R.
held at O. The value of the target value RO varies slightly depending on the type of internal combustion engine, but for example, in the case of a large two-stroke marine internal combustion engine, it is about 0.2.

Since the embodiment shown in FIG. 1 is a so-called proportional control system in which the deviation signal and the control signal are in a proportional relationship, the control deviation increases as the amount of throttling of the nozzle pitch of the turbine increases. Therefore, in a low load range with a large amount of throttling, Ps/pm
i becomes smaller than the target value RO, and the magnitude of the deviation depends on the gain of the amplifier 12. This embodiment has the advantage of reducing ps/pmi with the load and automatically correcting the influence of the load. Since the optimum ps/pmi value differs by several orders of magnitude between the normal use range and the low load range, this difference can be corrected by appropriately selecting the gain of the amplifier 12.

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 the PMI of all cylinders is measured and the average is taken, a more accurate internal combustion engine load can be determined and accurate control is possible, but it is expensive.

As another embodiment of the load detector, a torque meter may be provided on the output shaft of the internal combustion engine, and the output of this torque meter may be used as the load signal, 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.

Still other embodiments of the load detector may utilize means for sensing the amount of fuel per stroke of the piston. 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 relatively inexpensively compared to other embodiments.

In the case of an internal combustion engine that drives a generator, a wattmeter that detects the output of the generator may be used as the load detector. When using a wattmeter, it is necessary to determine the target value RO in consideration of the loss of the generator.

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

Furthermore, when the load changes suddenly due to startup or reversal, it is necessary to prevent the control system from becoming unstable by fixing the turbine nozzle pitch to a certain value.

Now considering the case where the two superchargers 1a and lb are controlled by separate control circuits, the characteristics of the control loop in the control system including the internal combustion engine 30 of the superchargers 1a and lb are as follows. There are differences as indicated by the references g 1 e g 2 in the figure. For the value d of ps/pmi, the supercharger 1
In the characteristic g1 corresponding to a, the nozzle pitch is small as shown by the value y1.

On the other hand, the characteristic g2 corresponding to the other supercharger 1b
In this case, the nozzle pitch y2 is large. Optimal value ps/Pm
The range of i is small, for example, about a large number. Therefore, even if the difference in the characteristics gl and gz is slight, the nozzles of the two superchargers may be biased toward fully closed and fully open. This difference in the life characteristics gl+g2 is due to the fact that when the superchargers 1a and lb are individually driven, the load detector of the drive section,
This is caused by the zero point drift of the air supply pressure detector, etc., and the difference in gain of the amplifier included in the control circuit. There are variations in electronic circuit elements such as transistors and resistors that make up such detectors and control circuits, and therefore the characteristics g
It takes a lot of adjustment time and cost to match l and g2. Further, although it is possible to make the characteristics g 1 e g 2 uniform by carefully selecting such electronic circuit elements, the productivity is poor.

The present invention solves these problems by commonly controlling multiple turbochargers with one control circuit, thereby improving the efficiency of the entire turbocharger and improving the fuel efficiency of the internal combustion engine. be done. Moreover, since only one control circuit is required for a plurality of superchargers, it is inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, and Fig. 2 shows the ratio ps/pmi of the supply pressure signal and the load signal and the nozzle pitch y.
FIG. 3 is a graph for explaining the present invention in detail. 1...Supercharger, 9...Drive unit, 10', 23...
Control circuit, 11... Limiter, 13... Divider, 1
4.°° Supply air pressure detector, 16... Indicator, 1
8...Arithmetic circuit, 22...Subtractor, 24...Load detector agent Patent attorney Kei Nishi Part - Figure 2 Figure 3 1) s/pmi Procedural amendment Commissioner of the Japan Patent Office Mr. 1, Display of the case Patent application No. 131J No. 131J Name of supercharger control device 3, Person making the amendment Relationship to the case Applicant address name (097) Yozaki Heavy Industries Forest Company Representative 4, Agent Address: 1-13-38 Nishihonmachi, Nishi-ku, Osaka Shinkoyaku Building 6, Yuzu of the claims of the specification subject to amendment, Details of the invention wL River 4
Both drawings and drawing 7, contents of amendment (1) Special afδG end fjiα are as shown in the attached sheet. (2) In the 4th line of page 5 of the Akira Fall Book Review, the phrase "air outlet 2a" is corrected to "air outlet 2." (3) Line 7 of shell number 6 on the statement! ;tr Correct the 10th line as shown in 1- below. The supply air pressure detector 14 is located in the intake air collecting pipe 37 between internal combustion and heating, and the pressure p5r in the result 1'□j.
To detect. The negative double detector 24 detects the pressure in the cylinder (jfl
Correct the indicator 16 to be displayed (4) 1 blade sum 1 fj) 7th line from the beginning of the 13th line to the 17th line as follows. Congratulations on the creation of such a control device. Shellfish 1 "v〃・
When the PS is lowered, the reduction in PS exceeds 1''level;
. Therefore, ps / pmii'j: 1jt. For this reason, 11i111 mountains 1tin! In the direction of the assistant (5) January 1flll 11-page 8th line 4th to 5th line, stop VCl-+1 as shown below. In the case of 1 IA as shown in the table, the intensity is 0.24. In general, when the internal combustion engine load is 1 degree Celsius, the fat air temperature also decreases and the density of the air increases, which improves the movement of air filling into the air 1d1, resulting in the optimum p / p ・S of
1111 111 (is also in the direction of decreasing 1 song. On the other hand, the secondary side 1 device [t shown in the first diagram is (II:i * (
Correcting the proportion of the control blade and injury (6) 1st column detail page 8 Mi line 11 is revised as follows: IJ:. , depends on oneself. This control device Iq corrects the load as well as p/p ・ST[]1 (7) '3411 and FIG. 3 as shown in the attached sheet. In the internal combustion engine equipped with the above-mentioned patent-claimed axial rotation mantissa variable pinch nozzle, Uchizuzeniso i31. It includes a detector that detects the operating condition 1μ of ll, and a 1lilJ control circuit that calculates and outputs the nozzle pinch based on the signal of this detector, and the A set of control equipment for a supercharger characterized by being commonly controlled by one circuit on the sub-side of the unit.

Claims (1)

[Scope of Claims] In an internal combustion engine equipped with a supercharger with a plurality of variable pitch nozzles, there is provided a detector that detects the operating state of the internal combustion engine, and a control circuit that calculates and outputs a nozzle pitch based on a signal from the detector. A control device for a supercharger, characterized in that a plurality of variable pitch nozzles are commonly controlled by the single control circuit.