JP3487357B2 - Supercharger for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas driven supercharger, a separate power generating turbine connected in parallel to a turbocharger turbine on the exhaust gas side, and a control for shutting down the turbine. And a supercharging device for an internal combustion engine having a mechanism.

[0002]

2. Description of the Related Art A supercharging device for an internal combustion engine of this type is known from EP-A-0091139. The cross-sectional area of the turbocharger turbine is narrower than that required for full load operation. This causes the turbocharger turbine to largely block the exhaust gases at engine partial load, so that the supercharger supplies a relatively high supercharged air pressure in the lower load range operation. The power generation turbine is suddenly turned on or off when a predetermined engine partial load is reached. Exhaust gas driven turbochargers and power generating turbines are designed to achieve the desired boost air pressure at full load when the turbine is turned on.

When the power generating turbine must be shut off in the upper load range due to a fault, the boost air pressure rises to an unacceptable value. At that time, the maximum allowable engine speed and the allowable cylinder pressure of the exhaust gas driven supercharger may be exceeded.

Further, the rapid introduction of the turbine for power generation
The result is that the means for transmitting the power of the turbine to the load is also suddenly loaded. Significant damage can occur, for example, in gear transmissions and especially in automatic overrun clutches. Further, the rapid injection of the power generation turbine causes a rapid decrease in the supercharging air pressure, which causes a shortage of air, which may cause a large heat load on the structural parts of the combustion chamber.

Setting the exhaust gas driven turbocharger and the turbine for power generation to the desired supercharging air pressure at full load does not produce the best supercharging air pressure for the engine in the power range mainly utilized. Means that.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to prevent a turbocharger of an internal combustion engine of the type described at the beginning from shorting the supercharging air because the turbine for power generation is not rapidly turned on and off. In the case of a failure in the upper load range, the turbine for power generation is shut off without impairing the operation of the internal combustion engine, and improvement is performed so that the best boost air pressure is achieved at the main operation output. It is in.

[0007]

According to the invention, the object is to provide a supercharger for an internal combustion engine of the type mentioned at the outset.
A bypass pipe is provided in parallel with the power generation turbine, and this bypass pipe has a control mechanism for opening and closing it, and when the bypass pipe has an open cross-sectional area, it is almost the same as the power generation turbine. Sized to allow the same exhaust gas flow through, the controlled variable for turning on and off the turbine for power generation is supercharged air pressure, and the control mechanism adjusts the opening and closing speed of the through-flow cross-section individually The control mechanism is equipped with a control device that allows the supercharging air pressure to fluctuate very little during the making and shutting-off process. Solved by designing the turbocharger and power generation turbine to achieve the best boost air pressure at 75-90% engine power It is.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings.

In FIG. 1, an internal combustion engine 1 is supplied with compressed air via a compressor 2 of an exhaust gas drive type supercharger 3. The supercharger turbine 4 to which the exhaust gas of the internal combustion engine 1 is supplied drives the compressor 2. The turbocharger turbine 4 and the power generation turbine 5 are connected in parallel on the exhaust gas side.
A shut-off valve 7 in the form of a directional control valve is arranged in the supply line 6 to the turbine 5. The shutoff valve 7 is automatically opened and closed at a predetermined supercharging air pressure of the exhaust gas driven supercharger.

In the above-mentioned supercharger having a particularly high efficiency supercharger, the output of the supercharger turbine 4 of the exhaust gas driven supercharger is larger than the required supercharger power, and the extra output is It is used to increase the effective output of the engine. Part of the exhaust gas guided to the exhaust gas driven supercharger turbine 4 is guided to the power generation turbine 5 through the supply pipe 6. Therefore, the excessive output of the exhaust gas energy is absorbed by the turbine 5 and given to the crankshaft 10 of the internal combustion engine 1 via the transmission 9. Exhaust gas pipe 1 of turbine 5
1 and the exhaust gas pipe 12 of the exhaust gas driven supercharger 3 are open to a common exhaust gas collecting pipe 13. A bypass pipe 14 having a throttle 15 and a shutoff valve 16 is arranged in parallel with the power generation turbine 5. The bypass pipe 14 is set so that when the shutoff valve 16 is open and the shutoff valve 7 is closed, the exhaust gas flow rate can be almost the same as that of the turbine 5. The throttle 15 is the turbine 5
Has the purpose of producing a pressure gradient corresponding to the turbine 5 when the engine is not operating. As a result, the turbine 5 is shut off by the shut-off valve 7 in front of it without affecting the supercharging of the internal combustion engine.

The supercharger is designed for a flow rate which is compatible with most engine operating speeds. That is, the exhaust gas driven supercharger 3 and the power generation turbine 5 are designed so that the best supercharged air pressure is achieved at the main operation output of about 75 to 90% of the maximum engine load. Of course, the boost air pressure deviates from the best value at small partial loads and full loads. However, this is not a disadvantage, since the internal combustion engine 1 is operated only for a small part of the operating time in this range.

Since the supercharging air pressure has a great influence on the heat load of the supercharging device, the signal for turning on the power generation turbine 5 is derived from the supercharging air pressure. The value of this supercharged air pressure is selected in relation to the engine load. As a result of experiments, it was found that turning on and off the turbine 5 was effective only in the middle range of the engine load.

FIG. 2 shows a diagram in which the abscissa represents the engine load in%, and the ordinate represents the supercharging air pressure P _L in bars. The curve A shows the relationship between the supercharging air pressure P _L and the engine load when the turbine 5 is shut off, and the curve B shows the same relationship when the turbine 5 is turned on. When the internal combustion engine 1 is rotating at high speed, the shutoff valve 7 in front of the turbine 5 starts to open when the supercharging air pressure reaches a predetermined value C. This reduces the supercharged air pressure. When the supercharging air pressure falls below a predetermined lower value D,
The opening process of the shut-off valve 7 in front of the turbine 5 is interrupted. The supercharged air pressure then increases again as the engine load increases. This process is repeated until the shutoff valve 7 is fully opened. This characteristic is the zigzag partial curve E of the diagram.
Indicated by. The supercharged air pressure therefore remains in the narrow range defined by the predetermined values C and D during the switching process of the shut-off valve 7, whereby an air-deficient condition and the disadvantages which result therefrom are avoided.

In the first embodiment shown in FIG. 3, this characteristic is realized by pneumatic control of the control mechanisms 7, 19, 16, 21. The shut-off valve 7 of the power generating turbine 5 in the form of a directional control valve is supplied with compressed air via a pressure pipe 17 on the input side. A further shut-off valve 18 in the form of a directional control valve is arranged in this pressure line 17 in front of the control mechanism or throttle 19 and in front of the directional control valve 7. The directional control valve 18 is operated in relation to the supercharged air pressure, which acts as a controlled variable. The directional control valve 18 is closed in the released basic position and is opened against the restoring force of the spring when the supercharged air pressure increases. The control mechanism of the bypass line 14, i.e. the control of the throttle element 21 and the shut-off valve 16, controls the pressure on the input side of the shut-off valve 16 in the form of a directional control valve, which is connected to a source of compressed air (not shown) and which guides the compressed air. This is done by connecting the pipe 20. As is known, throttle valves 22, 23, 2
The throttle elements 19, 21 consisting of 4, 25 and check valves 26, 27, 28, 29 have the purpose of slowing the respective pressure increase or pressure drop. Since the bypass pipe 14 may be opened only when the power generating turbine 5 is shut off, the pressure pipe 20 is released through the electromagnetic directional control valve 30. When operating the turbine 5, the directional control valve 31 is opened and the directional control valve 30 is closed. However, when a failure occurs in the turbine 5, the directional control valve 30 is turned on and the directional control valve 31 is closed, whereby the shutoff valve 16 of the bypass pipe 14 is opened by compressed air and the directional control valve 18 of the pressure pipe 17 is opened. Is closed by the spring force. The operation of the electromagnetic directional control valves 30, 31 is very quick.

When the engine load decreases, the turbine 5
The shutoff of is done in the opposite direction, similar to its turn. The control mechanisms 7, 19 of the turbine 5 and the control mechanisms 16, 21 of the bypass pipe 14 are designed such that they can be opened and closed with an operating time of 20 to 120 seconds.

FIG. 4 shows the electric control system of the embodiment of FIG. The pressure pipe 17 is connected to the current conductor, and the directional control valve 3
Switches 0 and 31 are replaced with switches. The supercharged air pressure is introduced as an electric input signal to a host controller (computer) not shown. This computer is a digital control unit for controlling electric servomotors 32 and 33 for adjusting the positions of the shutoff valves 7 and 16 formed as directional control valves of the turbine 5 and the bypass pipe 14 on the basis of stored target values. Issue an output pulse. The closing process and the closing process proceed similarly to the pneumatic type of FIG. 3, in which case the push button switch 34 is moved to the position shown in FIG.
The function of the directional control valve 18 in FIG.

The control mechanisms 7, 19, 16, 2 in FIG.
In the pneumatic control method of No. 1, supercharging air is supplied to the input side of the cutoff valve 16 of the bypass pipe 14 through the cutoff valve 18, and the power generation turbine 5 is turned on as in the embodiment of FIG. Done. When the switching process is complete, the bypass pipe 14 is completely opened, and all other conditions for the operation of the turbine 5 are fulfilled, the bypass pipe 14
Shut-off valve 16 is closed, and at the same time shut-off valve 7 of turbine 5 is opened for the above-mentioned operating time. The difference from the embodiment in FIG. 3 is that the supercharged air passing through the directional control valve 18 controls the compressed air for the shutoff valve 16 of the bypass pipe 14, and the compressed air is applied to the shutoff valve 7 of the turbine 5 on the input side. It is in. Similarly, directional switching valves 30, 31 that can be switched electromagnetically
Switching is performed via. That is, a control mechanism is provided in the pressure pipes or the lead wires 17 and 20, and the exhaust gas flow rate is throttled by this control mechanism or interrupted by the shutoff valves 7 and 16. Therefore, the control mechanisms 7, 16, 19, 21
Is designed such that the opening and closing speed of the cross-flow area can be adjusted individually.

As shown in FIG. 6, it is advantageous to arrange an auxiliary shut-off valve 35 in the exhaust gas supply pipe 6 in front of the turbine 5 which can be switched or closed in a time of less than 1 second. Similarly, the shutoff valve 36 that opens quickly is the bypass pipe 1
4 is arranged in the flow pipe 37 in parallel with the shut-off valve 16. Both of these auxiliary shutoff valves 35, 36 enable the turbine 5 to be stopped in an emergency.

When a condition for shutting off the turbine for power generation occurs, such as an oil shortage, an overspeed, a vibration alarm, etc., the turbine 5 is shut down without affecting the operation of the internal combustion engine. If the shutoff valve 16 in the bypass pipe 14 is designed to open sufficiently quickly in case of an emergency stop of the turbine 5, a separate shutoff valve 36 that opens quickly can be omitted.

[0020]

According to the present invention, the power generation turbine is not rapidly turned on and off, the supercharged air is not insufficient, and the turbine is the internal combustion engine when a failure occurs in the upper load range. It is shut off without disturbing the operation of the vehicle and the best boost air pressure is achieved at the main operating power.

[Brief description of drawings]

FIG. 1 is a principle system diagram of a supercharging device for an internal combustion engine including an exhaust gas drive type supercharger and a power generation turbine connected in parallel to the supercharger.

FIG. 2 is a diagram showing a relationship between supercharged air pressure and engine load.

FIG. 3 is a principle system diagram of a pneumatic control system of a control mechanism according to the present invention.

FIG. 4 is a principle system diagram of an electric control system of a control mechanism.

FIG. 5 is a principle system diagram of a pneumatic control system having different control mechanisms.

FIG. 6 is a principle system diagram of an emergency stop system of a power generation turbine.

[Explanation of symbols]

1 Internal combustion engine 3 Exhaust gas driven supercharger 4 supercharger turbine 5 Power generation turbine 7 Shut-off valve 14 Bypass piping 16 shut-off valve 18 Shut-off valve 19 Aperture element 21 Aperture element 30 shut-off valve 31 shut-off valve

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 64-60720 (JP, A) Actually opened 64-36624 (JP, U) Actually opened 63-200633 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) F02B 41/10

Claims (7)

(57) [Claims] 1. An exhaust gas driven turbocharger (3) and a separate turbocharger turbine (4) connected in parallel on the exhaust gas side and supplying power to the internal combustion engine (1) via a transmission device. Has a power generation turbine (5) and a control mechanism (7 , 19 ) for stopping the operation of the turbine, and the output of the supercharger turbine (4) is set for a predetermined partial load region, In the supercharger for an internal combustion engine, in which the power generation turbine (5) is shut off during partial load, a bypass pipe (14) provided with a control mechanism (16, 21 ) in parallel with the power generation turbine (5) is provided. This bypass pipe (14) is provided and a control mechanism (16,
21) and the bypass pipe (14) is dimensioned to allow a flow-through of about the same exhaust gas flow as the turbine (5) when the cross-flow cross-section is open, and the turbine for power generation (5) The control amount for turning on and off the control mechanism (7 , 19 ) of (1) is the supercharging air pressure of the exhaust gas drive type supercharger (3), and the control mechanism (7 , 19 ) controls the control device (18, 31; 31, 34) is opened at a lower limit value (D) of the supercharging air pressure set in advance and is closed at an upper limit value (C), and an exhaust gas driven supercharger (3) and a power generation turbine (5) Generate the best supercharging air pressure at an engine output of 75 to 90%. Wherein become since control Organization has shutoff valve (7, 16) and aperture element (19, 21), the control equipment is directional control valve (18) and electromagnetically actuated directional control valve (30, 31) 2. The supercharger according to claim 1, wherein the supercharger and the mechanism are connected to a host computer. 3. Supercharging device for an internal combustion engine according to claim 2, characterized in that the input side of the shut-off valve (7) in front of the turbine (5) is energized in relation to the supercharging air pressure. 4. Shut-off valve (16) for bypass piping (14)
3. The supercharging device according to claim 2, wherein the input side of the is charged in relation to the supercharging air pressure. 5. The auxiliary shut-off mechanism (35) which can be closed in less than 1 second before the turbine (5) and the closing in less than 1 second connected in parallel to the first shut-off valve (16) of the bypass pipe (14). Supercharging device according to one of the preceding claims, characterized in that a shut-off valve (36) is provided. 6. The supercharging device according to claim 1, wherein the supercharging pneumatic pressure characteristic is realized by a pneumatic control device. 7. The supercharging device according to claim 1, wherein the supercharging pneumatic pressure characteristic is realized by an electric control device.