JPH0517382B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a supercharger system for diesel engines, particularly for use in general vehicles, cargo handling machines, construction machines, special vehicles, ships, etc. The present invention relates to a turbo compound engine that can be widely used in 2-stroke and 4-stroke internal combustion engines.

[Conventional technology]

As shown in FIG. 4, an example of a conventional turbo compound engine is configured, and exhaust gas is guided from an exhaust pipe 2 of an engine 1 to a turbine 9 of an exhaust turbo supercharger 10, which drives a compressor 8. and pressurize the intake air. By applying pressure,
The pressurized air whose temperature has increased is cooled by the charge air cooler 3 and then supercharged to the engine 1 through the charge air pipe 4.

In a normal exhaust turbocharged engine, the energy of the exhaust gas emitted from the turbine 9 of the exhaust turbocharger 10 is exhausted into the atmosphere, but in a turbo compound engine, a low pressure recovery turbine is installed downstream of the turbine. 7 and is mechanically coupled to the crankshaft 5 of the engine 1 via the reduction gear train 6, the exhaust energy can be effectively recovered by the low pressure recovery turbine 7 and the performance of the engine can be improved. ing.

[Problem that the invention seeks to solve]

The conventional engine configured as described above has the following problems.

(1) It is possible to improve the performance of a turbo compound engine in the high load range where the amount of recovered exhaust energy is large, but in the low speed range and medium to low load range where the amount of recovered exhaust energy is small, it is possible to improve the performance by using the recovery turbine 7 and the reduction gear train 6. We cannot expect performance improvements to outweigh the disadvantages such as engine pumping loss and friction loss.
It is difficult to improve performance over a wide engine speed and load range.

(2) Since the recovery turbine is a low-pressure type, the outer diameter of the turbine is large, and the engine itself cannot be made lightweight and compact due to piping between the exhaust turbocharger and the recovery turbine.

(3) Since the recovery turbine 7 is installed on the downstream side of the exhaust turbocharger turbine, the exhaust turbocharger blows up poorly under transient load conditions where the downstream side of the exhaust turbocharger turbine is throttled, resulting in good engine transient characteristics. do not have.

The present invention attempts to solve these problems, and aims to provide a turbo compound engine that can perform supercharging in accordance with the operating state of the internal combustion engine.

[Means for solving problems]

For this reason, the turbo compound engine of the present invention provides a power transmission system in which an exhaust turbo supercharger is provided in an internal combustion engine, and a gear train is provided between the exhaust turbo supercharger and the crankshaft of the internal combustion engine. a first one-way clutch 8a capable of transmitting power from the exhaust turbo supercharger to the crankshaft; and a first one-way clutch 8a capable of transmitting power from the crankshaft to the exhaust turbo supercharger. a second one-way clutch 8b that can be
The first and second clutches 7 can respectively connect and disconnect the power transmission path via the one-way clutch.
a, 7b, and a sensor that detects the operating state of the internal combustion engine, and outputs control signals to the first and second clutches respectively based on the detection signal of the sensor to control the engine at low to medium speeds and under low load. In this state, the second clutch 7b is connected and the exhaust turbo supercharger is driven by the clutch shaft, resulting in mechanical drive operation.
b is disconnected, the first clutch 7a is connected, and a part of the power of the exhaust turbo supercharger is recovered to the crankshaft. It is characterized by being equipped with a controller for exhaust turbo supercharging operation.

[Effect]

In the turbo compound engine of the present invention described above,
Based on control signals from the controller, the first and second clutches are respectively engaged and engaged, and the exhaust turbo supercharger mechanical drive state is in which the second clutch is connected, and the turbo compound state is in which the first clutch is connected. , and an exhaust turbocharging state in which both the first and second clutches are not connected.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figures 1 to 3 show a turbo compound engine as an embodiment of the present invention, Figure 1 is a schematic diagram showing its overall configuration, and Figure 2 is a schematic diagram showing the overall configuration. is a block diagram showing its control system, and FIG. 3 is a graph showing its operation.

As shown in FIG. 1, in the turbine section of the exhaust turbo supercharger 9, variable nozzles 12, which are variable stator blades, are arranged on the circumference outside of the turbine rotor blades 11. A variable drive ring 13 is connected to the variable nozzle 12 via a link.

The exhaust turbo supercharger 9 is connected to the engine crankshaft 5 via a power transmission system including a reduction gear train 6 . This reduction gear train 6 is used for power transmission between the exhaust turbocharger 9 and the crankshaft 5.
It is configured with a series of parallel gear trains. Between these gear trains, there are a first clutch 7a and a second clutch 7b that can be mechanically, electrically, or hydraulically disconnected according to control signals such as engine speed and load.
A first one-way clutch 8a and a second one-way clutch 8b are interposed, which are connected in series with the clutches 7a and 7b, respectively. The two one-way clutches 8a and 8b are configured so that the directions of power transmission between the exhaust turbocharger 9 and the crankshaft 5 via the gear train 6 are opposite to each other. That is, the direction of the arrow of the one-way clutches 8a and 8b in the figure indicates the direction of power transmission, and the power is not transmitted in the direction opposite to the arrow. Although the one-way clutches 8a and 8b inserted into each gear train 6 are essential components, one of the clutches 7a and 7b can be omitted if necessary. Therefore, in this gear train, when one gear train is connected and power is transmitted by the action of clutches 7a, 7b and one-way clutches 8a, 8b, the other gear train can be brought into a disconnected state,
It is also possible to put both gear trains in a disconnected state. The rest of the configuration is the same as in Figure 4.
It consists of an engine 1, an exhaust pipe 2, an air supply cooler 3, an air supply pipe 4, etc.

The control system in this embodiment is
It is configured as shown in the figure, and the variable nozzle 12
An actuator 16 is connected to a drive ring 13 via a link. The actuator 16 is connected to a microcomputer 22 as a controller via a variable nozzle opening/closing drive circuit 24, and the microcomputer 22 controls engine rotational speed, compressor outlet air supply pressure,
The optimum nozzle area is calculated for the fuel injection amount, turbine inlet temperature, etc., and is output to the variable nozzle opening/closing drive circuit 24. The actuator 16 is driven by the control signal from the drive circuit 24, and the variable nozzle opening is controlled. It is now possible to adjust the

Clutches 7a and 7b are interposed in the reduction gear train 6 that connects the exhaust turbocharger 9 and the crankshaft 5.
is the operating state of the engine 1 and the exhaust turbo supercharger 9, that is, the mechanical drive state in which the engine 1 drives the exhaust turbo supercharger 9, and the turbine exhaust energy is recovered from the exhaust turbo supercharger 9 to the engine 1 side. This system controls three states according to engine usage conditions and load conditions: a turbo compound state with no mechanical connection between the engine 1 and the exhaust turbo supercharger 9, and a full turbo state with no mechanical connection between the engine 1 and the exhaust turbo supercharger 9. A microcomputer 22 serving as a controller selects a desired state from among three states depending on the injection amount, compressor outlet pressure, etc., and a control signal from a clutch intermittent drive circuit 23 selects a desired state from among three states.
Clutch disengagement actuators 17a and 17b are operated to engage and disengage the clutches 7a and 7b.

When the engagement and engagement of the clutches 7a and 7b is controlled solely by the engine speed, a centrifugal clutch that can be engaged and engaged mechanically or a hydraulic clutch that can be engaged and engaged using engine lubricating oil pressure can also be used. The optimum timing of the injection timing change actuator 15 of the fuel injection pump 14 is calculated by the microcomputer 22 according to the usage conditions and load conditions of the engine, and the injection timing change actuator 15 is controlled by a control signal from the injection timing change drive circuit 25. is operated, the fuel injection pump 14 is adjusted, and the injection timing is determined.

In the illustrated example, the fuel injection pump 14 is shown as a row-type injection pump, so the injection timing change actuator 15 corresponds to a so-called electronic timer. In some cases, it is configured with a corresponding injection timing changing mechanism.

By the way, the microcomputer 22 is provided with a throttle opening sensor 18 and an engine rotation speed sensor 19 to detect the operating state of the engine, and the engine rotation speed is determined by the engine rotation speed sensor 19,
The fuel injection amount is detected by the throttle opening sensor 18 of the fuel injection pump 14 and is input to the microcomputer 22.

Then, the compressor outlet pressure is determined by pressure sensor 2.
0, the turbine inlet exhaust temperature is measured by temperature sensor 2.
1 and A/D converters 26, 26, respectively.
The data is inputted to the microcomputer 22 via 27. Microcomputer 2
2 is configured to execute digital arithmetic processing by software according to a predetermined control program, and includes a CPU, RAM, ROM, and I/O.
It is constructed with the O circuit section etc. as the main part.

Then, the microcomputer 22 has a third
A map for determining driving conditions as shown in the figure is built-in, and calculations are performed according to the map.

Since the turbo compound engine as an embodiment of the present invention is configured as described above, the third
The microcomputer 22 calculates which state corresponds to the three supercharging states A, B, and C of the exhaust turbo supercharger and the engine as shown in the figure. Then, the reduction gear train clutch, turbine nozzle area, and injection pump advance angle characteristics are adjusted to correspond to each supercharging state.

That is, in order to improve the start-up acceleration required for a vehicle engine, the second clutch 7b is turned on in the low-medium speed and low-medium load range C, and mechanical drive of the exhaust turbo supercharger is performed. On the other hand, in medium-high speed and high load range A, the second clutch 7b
OFF, the first clutch 7a is turned ON, the exhaust turbo supercharger 9 turbine is operated in a turbo compound state, surplus output is recovered to the engine side, and engine performance is improved. At this time, the turbine nozzle area is adjusted to be small to the position shown by the chain line in the exhaust turbo supercharging state where the one-way clutches 8a and 8b are OFF, as shown by the solid line in the figure, and the injection pump is also adjusted to the position shown by the chain line in the exhaust turbo supercharging state. The angle is delayed as shown in . In other speed and load ranges, the clutches 7a and 7b are adjusted to the OFF state, and the engine is operated in an exhaust turbocharged state.

According to the engine of this embodiment, the following effects or advantages can be obtained.

(1) The exhaust turbo supercharger 9 can be mechanically driven from the engine 1 via the reduction gear train 6.

(2) Excess energy of the exhaust turbocharger 9 turbine can be recovered to the engine 1 via the gear train 6.

(3) Clutch 7 inserted in reduction gear train 6
By turning off a and 7b, the exhaust turbo supercharger 9 can be operated in a full turbo state without being mechanically coupled to the engine.

(4) Clutches 7a and 7 inserted into the reduction gear train 6
The above can be achieved by connecting and disconnecting b by the engine control signal.
The operating conditions of the exhaust turbo supercharger 9 (1), (2), and (3) can be controlled according to the conditions necessary for the engine. In this case, the power transmission system is constructed by arranging two sets of power transmission paths each consisting of a one-way clutch and a clutch, and the above (1).
(2) and (3) are operated by operating the clutches of these two sets of power transmission lines separately, so there is no risk of malfunction, and each operation mode can be switched using a simple device. Can be done accurately.

(5) By controlling the area of the variable nozzle 12 of the turbine in the exhaust turbocharger 9 using an engine control signal, item (4) can be controlled more precisely.

(6) The engine can be made more compact than the low-pressure turbine recovery turbo compound engine.

〔Effect of the invention〕

As detailed above, the turbo compound engine of the present invention has a simple configuration and can be operated in three states: mechanical drive, full turbo, and turbo compound depending on the rotational speed and load conditions required for the engine. You will be able to do this, and the following effects and benefits will be obtained.

(1) The mechanical drive of the exhaust turbocharger provides excellent start-up acceleration as a vehicle engine.

(2) Engine performance (high output, low fuel consumption) is achieved by turbo compound operation at medium to high speeds and high load ranges.

(3) In the rotation speed and load range where the supercharging conditions in paragraphs (1) and (2) are disadvantageous to the engine performance, it is possible to operate in a full turbo state, so paragraphs (1) and (2) It is possible to compensate for the disadvantages that arise when supercharging is forced to take place within the disadvantageous range described above.

(4) Since it is a single-stage exhaust turbocharger, the entire engine including the turbocharger can be kept compact despite multi-function supercharging operation.

(5) The power transmission system is composed of two sets of power transmission paths consisting of a one-way clutch and a clutch, and the operation mode is switched by individually engaging and disengaging the clutches of each set. Mode switching can be performed accurately and with a simple device.

[Brief explanation of the drawing]

Figures 1 to 3 show a turbo compound engine as an embodiment of the present invention. Figure 1 is a schematic diagram showing its overall configuration, Figure 2 is a block diagram showing its control system, and Figure 3 is a This is a graph showing its operation, and FIG. 4 is a system configuration diagram of a conventional low pressure turbine recovery turbo compound engine. DESCRIPTION OF SYMBOLS 1...engine, 2...exhaust pipe, 3...supply air cooler, 4...supply air pipe, 5...crankshaft, 6...reduction gear train, 7a...first clutch, 7b...first 2 clutches, 8a...first one-way clutch, 8b...second one-way clutch, 9...
Exhaust turbo supercharger, 10... Compressor, 11
...Turbine rotor blade, 12...Variable nozzle, 13...
...Drive ring, 14...Fuel injection pump, 15...
...Injection timing change actuator, 16...
Actuator, 17a, 17b... Actuator for clutch engagement, 18... Throttle opening sensor, 19... Engine rotation speed sensor, 20... Pressure sensor, 21... Temperature sensor, 22... Microcomputer as controller, 23 ……
Clutch intermittent drive circuit, 24... Variable nozzle opening/closing drive circuit, 25... Injection timing change drive circuit, 26, 27... A/D converter.

Claims (1)

[Claims] 1. An internal combustion engine is equipped with an exhaust turbo supercharger and a power transmission system with a gear train interposed between the exhaust turbo supercharger and the crankshaft of the internal combustion engine, and the power transmission system is , a first one-way clutch 8a capable of transmitting power from the exhaust turbocharger to the crankshaft, and a second one-way clutch 8b capable of transmitting power from the crankshaft to the exhaust turbocharger; A power transmission path via the first one-way clutch and the second one-way clutch.
first and second clutches capable of connecting and disconnecting the power transmission path via the one-way clutch;
a, 7b, and a sensor that detects the operating state of the internal combustion engine, and outputs control signals to the first and second clutches respectively based on the detection signal of the sensor to control the engine at low to medium speeds and under low load. In this state, the second clutch 7b is connected and the exhaust turbo supercharger is driven by the crankshaft, resulting in mechanical drive operation.
b is disconnected, the first clutch 7a is connected, and a part of the power of the exhaust turbo supercharger is recovered to the crankshaft. A turbo compound engine, characterized in that it is provided with a controller for exhaust turbocharging operation.