JPH02140432A - Fuel injection amount controlling device for internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the generation of black exhaust gas smoke by installing a cut-off valve to interrupt the supply of supercharging pressure for controlling a boost compensator, and a control mechanism to change over the cut-off valve. CONSTITUTION:An exhaust gas turbo supercharger 13 is installed between the exhaust gas system 11 and the air supply system 12 of an internal combustion engine 10. A root type mechanical supercharger 21 is installed midway of an air supplying passage 20. A control valve 27 is inserted midway of a bypath passage 26. When the amount of supercharged air from the mechanical supercharger 21 is excessively large, a relief valve 29 is opened to discharge part of the supercharged air to the upstream side of the bypath passage 26, so that the generation of black exhaust smoke can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection amount control device for an internal combustion engine that uses a so-called hybrid mechanical supercharger and an exhaust turbo supercharger.

(Prior art and its problems) As is well known, a mechanical supercharger called a supercharger has a high supercharging capacity in a low speed range, and an exhaust turbo supercharger has a high supercharging capacity in a high speed range. Or expensive.

When using an internal combustion engine as a marine main engine for driving a screw, it is recommended to use both of the above-mentioned superchargers in combination due to low-speed navigation in a /8 bay and the frequency of forward and reverse switching.
It is effective.

In the field of this type of combination engine, a prior art in which the operation of a mechanical supercharger is controlled by an electromagnetic clutch is already known, for example, in Japanese Patent Laid-Open No. 149521/1983.

Furthermore, for engines equipped with exhaust turbo superchargers, fuel injection pumps equipped with boost compensators that increase the amount of fuel injected in order to increase output at high speeds are also known.

However, in an undeveloped system that uses a mechanical supercharger with good supercharging performance from a low rotation range, the characteristic X1 in Fig. 7, which is a graph of engine rotation speed N vs. injection pump rack position R,
The boost compensator increases fuel in a rotation range lower than the characteristic Therefore, there is a problem that black smoke is generated in the exhaust gas (the concentration of the exhaust gas becomes high) in the region S1.

In addition, as shown in Figure 8, from the conventional characteristic X2 that increases the rack position in the low rotation range, simply increasing the increase start pressure of the boost compensator and increase the increase start rotation speed will cause the switch to the exhaust turbo supercharger. There is also a possibility that the rack position will temporarily shift at S2 as shown in characteristic X3.

(Object of the Invention) The present invention provides a fuel injection amount control device for an internal combustion engine with a boost compensator that can prevent the generation of exhaust black smoke due to fuel increase operation of the boost compensator in a so-called hybrid supercharged engine equipped with a boost compensator. It is intended to.

(Structure of the Invention) (1) Technical Means The present invention provides an exhaust turbo supercharger between an exhaust system and an air intake system of an internal combustion engine, one end of which is connected to a blower of the exhaust turbo supercharger, and the other end of which is connected to a blower of the exhaust turbo supercharger. In internal combustion engines equipped with a supercharger, in which a mechanical supercharger is installed in the middle of an air supply passage that opens to the atmosphere, and a boost compensator is installed in the fuel injection pump, this switch is used to intermittent the supply of boost pressure to control the boost compensator. Provide a valve;
A control mechanism is provided to switch the switching valve so that the rotational speed is higher than the rotational speed at which the fuel increase operation is performed when the rotational speed increases, or the rotational speed at which the fuel increase is stopped when the rotational speed decreases, and the mechanical supercharger and the exhaust turbo are In the medium and low speed range where the twin h with the supercharger operates, the switching operation range by the control mechanism is set to an engine rotation speed at which the amount of air supplied by both superchargers increases and the exhaust gas concentration does not become high. This is a fuel injection amount control device for an internal combustion engine with a supercharger, characterized in that the setting is made later.

(2) Set the switching operation range by the action control mechanism to a rotation speed that does not increase the exhaust concentration even if the boost compensator operates to increase the fuel amount, and in that rotation speed range, the boost compensator does not increase the fuel amount. No exhaust black smoke is generated.

The switching control by the control mechanism is a hysteresis control in which the rotational speed at which the fuel increase operation is performed when the rotational speed increases is higher than the rotational speed at which the fuel increase is stopped when the rotational speed drops.
Boost compensator operation and operation in the stop +1- switching range become smoother.

(Embodiment) FIG. 1 shows a case in which the present invention is applied to a marine diesel engine, particularly a marine main engine for driving a ship's screw, and 10 is a diesel engine main body. Exhaust system 11 of engine body 10
An exhaust turbo supercharger 13 is provided between the air supply system 12 and the air supply system 12 . An exhaust pipe 15 is connected to the turbine 14 of the exhaust turbo supercharger 13 . An air supply pipe 17 is connected to the blower 16, and an intercooler 18 is interposed in the middle of the air supply pipe 17.

One end of an air supply passage 20 is connected to the blower 16, and the other end of the air supply passage 20 is open to the atmosphere. A roots-type mechanical supercharger 21 (supercharger) is provided in the middle of the air supply passage 20. F? The iV type supercharger 21 is, for example, a Bell l
-22 (Power transmission (llIi) etc. is used to extract power from the output shaft 23 of the engine body 10. An electromagnetic clutch 25 is interposed in the pulley 24 on the output shaft 23 side. When the clutch 25 is disengaged, the belt 22 does not rotate, thereby prolonging the life of the belt 22. Alternatively, a gear train, chain, etc. may be used for the belt 22.

A bypass passage 26 that bypasses the mechanical supercharger 21 is connected to the air supply passage 20, and a control valve 27 is interposed in the middle of the bypass passage 26.

The control valve 27 has a structure in which a check valve 28 and a relief valve 29 are integrated. When the mechanical supercharger 21 is stopped, the check valve 28 opens to supply atmospheric air to the blower 16 through the bypass passage 26 that bypasses the mechanical supercharger 21. When in operation, the reverse 11-valve 28 is closed, and when the amount of supercharging air in the mechanical supercharger 21 is too large, the relief valve 29 is opened and a part of the supercharging air is diverted to the bypass passage 26. It is designed to be released upstream.

In FIG. 2 showing a control device for the electromagnetic clutch 25, reference numeral 30
is a rotation sensor that detects the rotation speed of the output shaft 23 in a non-contact manner. The detection signal 31 of the rotation sensor 30 is input to the controller 32, and after signal processing is performed by the controller 32, the controller 32 outputs a control signal 33 to the electromagnetic clutch 25. The control signal 33 controls the electromagnetic clutch 25 on and off at a rotation speed of about 70% of the rated speed, and connects the electromagnetic clutch 25 at medium to low speeds and disconnects it at high speeds.

This engine body 10 includes a fuel injection pump 4 as shown in FIG.
It is equipped with 0. The fuel injection pump 40 is provided with a boost compensator 41, and the boost compensator 41 includes solenoid valves 5iVI 5SV2 (
Pipes 42 and 43 of the switching valve) are connected. A pipe 44 connected to the intake pipe 17 is connected to the solenoid valve SVI, and a pipe 45 whose one end is open to the atmosphere is connected to the solenoid valve SV2. The boost compensator 41 increases the fuel injection amount when the pressure of the supercharging air sent from the pipes 44, 43 reaches a predetermined pressure.

In addition, in order to communicate with the atmosphere so that pressurized air does not remain in the diaphragm chamber of the boost compensator 41,
Solenoid valves SV1. Although SV2 is provided,
If a three-way valve is used, only one switching valve is required.

The controller 32 (control mechanism) outputs control signals 46 and 47 for controlling the solenoid valves SVI and SV2. First, control signal 4 that controls opening and closing of Svl
6, as shown in characteristic X5 in FIG. 4, when the rotational speed N increases, the solenoid valve SVI is switched from closed to open with N4, and when the rotational speed N is decreased, the solenoid valve SVI is switched from open to closed with N3. Control signal 47 that controls opening and closing of solenoid valve SV2
When the rotational speed increases as shown in characteristic X6, the solenoid valve SVI is switched from open to closed with N4, and when the rotational speed decreases, it is switched from closed to open with N3. The rotation speed N can be operated from Nl at idle to N2 at rated time, and N2
The electromagnetic clutch 25 is intermittent at 0.7XN2, which is 70% of the
Exhaust turbo supercharger 13 and mechanical supercharger 21 in operating range N5
is used in combination, and only the exhaust turbo supercharger 13 is operated in the operating range N6. The above controller 32 and solenoid valve SV1. The air supply control device 50 is composed of the SV2 and the like.

As shown in FIG. 5, this air supply control device 50 has a characteristic X8 in which the rack position R rises and falls between R2 and RO in the range N3 to N4, where the rotation speed is higher than the conventional characteristic X7.
It looks like this. When the number of revolutions N increases, the rack position rises at N4, which is higher than N3, and when the number of revolutions N decreases by one step, the rack position drops at N3. Therefore, when the rack position is increased (increased fuel amount), black smoke is generated at N3 where the rotational speed N is higher than the NFL area S1.
Since the rack position R is raised and lowered within the range of N4, the amount of fuel is increased while the amount of air supply increases, and there is no risk of generating black smoke even if the boost compensator 41 operates.

In this FIG. 5, since the mt increase starting pressure is not increased, the region S2 in FIG. 8 does not occur.

In addition, the boost compensator 41 is R2 before operating.
is from R1 when only the exhaust turbo supercharger 13 is provided,
The rack position R has risen by the amount by which the supercharging of the mechanical supercharger 21 has been added.

Next, the effect will be explained. For example, FIG. 6 shows a case where the engine is suddenly accelerated from N1 at idle. In Fig. 6, which is a graph of elapsed time after the start of acceleration T - rack position R1 engine speed N1 black smoke density B, the rack position R rises to R2 at T-0 as shown in characteristic X9, and as shown in Fig. 5. Similarly to characteristic X8, boost compensator 41 (
(Fig. 3) performs the fuel increase operation. With this TI, the rack position rises more slowly than with the characteristic XIO in the conventional case.

Therefore, in the case where the conventional characteristic

On the other hand, if the fuel increase operation of the boost compensator 41 is delayed as in the embodiment of the present invention, the black smoke tolerance value B1 will not be exceeded as in characteristic X12.

Further, regarding the acceleration performance at the rotational speed N, characteristics XI4, which are almost the same as characteristics XI3 in the conventional case, are maintained.

The rack position R rises at the rotational speed Nl.

(Effects of the Invention) As explained above, in the fuel injection amount control device for a supercharged internal combustion engine according to the present invention shown in FIG.
Since the switching operation range by 2 (control mechanism) is set to a high rotational speed that allows the supply air m to be obtained without increasing the exhaust gas l ratio, even if the boost compensator 41 operates to increase the fuel amount, the rotation speed will not change as shown in Fig. 6. It is possible to prevent the generation of exhaust black smoke.

As shown in FIG. 5, the switching control by the controller 32 is hysteresis controlled so that the rotational speed at which the fuel increase operation is performed when the rotational speed increases is higher than the rotational speed at which the fuel increase is stopped when the rotational speed decreases. 4
Operation in the operation/stop switching range of 1 can be made smoother.

[Brief explanation of the drawing]

Fig. 1 is a schematic structural diagram of a supercharged engine adopting the present invention, Fig. 2 is a structural schematic diagram showing the control system of the electromagnetic clutch, Fig. 3 is a structural schematic diagram showing the air supply control device, and Fig. 4 is the engine rotation speed. - Graph of switching valve opening/closing, Figure 5 is a graph of engine rotation speed - rack position, Figure 6 is a graph of elapsed time after acceleration starts - rack position, engine rotation speed, black smoke concentration, Figures 7 and 8 Each figure is a graph for the conventional case. 10... Engine body, 13
...Exhaust turbo supercharger, 20...Air supply passage, 21...
・Mechanical supercharger, 32...controller, 40...
Fuel injection pump, 41...boost compensator,
SVI, SV2...Elapsed time of solenoid valve acceleration T

Claims (1)

[Claims] An exhaust turbo supercharger is installed between the exhaust system and the air supply system of an internal combustion engine, and a mechanical supercharger is installed in the middle of the air supply passage, with one end connected to the blower of the exhaust turbo supercharger and the other end open to the atmosphere. set up a machine,
In a supercharged internal combustion engine in which the fuel injection pump is equipped with a boost compensator that increases the amount of fuel injected when the load increases, a switching valve is installed to intermittent the supply of supercharging pressure to control the boost compensator. A control mechanism is provided for switching the switching valve so that the rotational speed at which the fuel increase operation is performed is higher than the rotational speed at which the fuel increase is stopped when the rotational speed drops, and both the mechanical supercharger and the exhaust turbo supercharger are operated. In the medium and low speed range where the engine operates, the switching operation range by the control mechanism is set after the engine speed reaches a speed at which the air intake by both turbochargers increases and the exhaust gas concentration does not become high. Features: A fuel injection amount control device for internal combustion engines with a supercharger.