JPS6332913Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharging device for an internal combustion engine equipped with an exhaust turbo supercharger and a positive displacement compressor.

Exhaust turbo superchargers are well known, in which a turbine rotates using the exhaust energy of an internal combustion engine drives a compressor linked to the turbine, which compresses intake air into the combustion chamber of the engine to improve intake efficiency. It is. In this internal combustion engine with an exhaust turbo supercharger, at low speeds and high loads, there is a lack of exhaust energy and the compression efficiency of the exhaust turbo supercharger decreases, resulting in a shortage of intake air amount for the internal combustion engine, resulting in output A shortage or deterioration of smoke density may occur. It is also well known that the response during acceleration is poor due to the inertia of the turbine.
In order to improve this response, the present applicant previously proposed in Utility Application No. 1973-73739 to improve the intake efficiency by bypassing the compressor of the exhaust turbo supercharger for intake air in the middle and high engine speed range. The company is proposing an internal combustion engine with a supercharger.

Furthermore, in order to suppress the deterioration of smoke concentration, some systems reduce the amount of fuel supplied in accordance with the small amount of intake air in the low engine speed range, but there is a problem in that the output decreases.

In contrast to this exhaust turbo supercharger, a positive displacement compressor is known which performs supercharging by being driven by the output of an internal combustion engine. This internal combustion engine with a positive displacement compressor has improved output over a wide range of rotational speeds, but
There is a problem in that fuel consumption deteriorates due to unnecessary excess air intake during partial load, and the drive horsepower increases as the speed increases.

For example, Japanese Patent Publication No. 41-8081 discloses a technique for introducing supercharged air from an exhaust turbo supercharger into a positive displacement compressor. However, when an exhaust turbo supercharger is installed on the upstream side, the temperature of the compressed air increases, so the positive displacement compressor must provide a gap for expansion to match the temperature rise. The volumetric efficiency of the mold compressor decreases. For this purpose, in this known technique, a supercharge air cooler is provided between the exhaust turbocharger and the positive displacement compressor. Therefore, the device must become larger and control becomes difficult.

Therefore, an object of the present invention is to provide a supercharging device for an internal combustion engine that can improve the suction efficiency in the low speed rotation range of the engine without increasing the size of the entire device, and which is relatively easy to control. .

According to the present invention, in a supercharging device for an internal combustion engine that includes an exhaust turbo supercharger and a positive displacement compressor, the positive displacement compressor is provided on the upstream side of an intake passage, and the exhaust turbo supercharger is provided on the downstream side of the positive displacement compressor. are installed in series, and a bypass passage is provided that bypasses the positive displacement compressor, and is opened and closed by signals from the rotational speed sensor and load sensor of the internal combustion engine, and when the rotational speed falls below a predetermined value or the load reaches a predetermined value. An opening/closing valve that closes when the exhaust gas exceeds the specified value is provided in the bypass passage, and an exhaust shutter is provided in the exhaust passage from the exhaust turbo supercharger, and the exhaust shutter is a solenoid valve that is activated when an exhaust brake switch is turned on. The solenoid valve is driven to open and close, and a driving means is provided for closing the solenoid valve to perform two-stage compression using the exhaust turbo supercharger and the positive displacement compressor when the solenoid valve is activated.

Therefore, at high speeds and low loads, the on-off valve of the bypass passage is open and the positive displacement compressor does not actually operate, so its operation is the same as when only a conventional exhaust turbo supercharger is installed. . for that,
It is possible to prevent excessive intake of air at low loads and an increase in drive horsepower at high speeds, which are disadvantages of positive displacement compressors.

However, at low speeds or high loads, the on-off valve of the bypass passage closes, so the intake air is first compressed by the positive displacement compressor and then flows to the exhaust turbo supercharger. Further, there is no need to take into account the thermal expansion of the positive displacement compressor, and the advantage of arranging the two in series can be utilized, allowing for sufficiently efficient operation.

The opening/closing valve may be controlled to open/close based on signals from the rotational speed sensor and the load sensor, and the control is easy. Therefore, according to the present invention, the engine can be operated efficiently regardless of the engine speed and the load. In particular, according to the present invention, when the exhaust brake is activated, the bypass passage is closed and the exhaust turbocharger and positive displacement compressor operate in series, thereby increasing friction horsepower and improving braking force. This not only improves efficiency during normal engine operation, but also improves braking efficiency when the exhaust brake is activated.
It is particularly suitable for large vehicles.

In carrying out the present invention, the driving means for closing the on-off valve for two-stage compression is preferably composed of a solenoid valve that cuts off the supply of compressed air and an air cylinder operated by the compressed air.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows an embodiment of the present invention designed to improve the intake efficiency of an internal combustion engine when the engine is running at low speed and under high load, during acceleration, and during exhaust braking. In the figure, intake passages 2a to 2d of the internal combustion engine 1 include
An exhaust turbo supercharger (hereinafter referred to as turbocharger) 3 and a positive displacement compressor (hereinafter referred to as supercharger) 4 are installed in series, while a bypass intake passage (hereinafter referred to as bypass passage) 5 is provided to bypass the supercharger 4. A normally open on-off valve 6 is interposed in the bypass passage 5. This supercharger 4 is connected to a pulley 1 which is connected and disconnected by a pulley 8, a belt 9 and an electromagnetic clutch 10 by a crankshaft 7 of an internal combustion engine 1.
1, and the on-off valve 6 is driven by a solenoid valve 12.
It is designed to be opened and closed by an air cylinder 13 controlled by.

The electromagnetic clutch 10 and the electromagnetic valve 12 are connected via a line 14 to a rotation speed sensor 15 that detects the rotation speed of the internal combustion engine 1 arranged in parallel and outputs a signal when the rotation speed is below a certain value, and a vehicle equipped with the internal combustion engine 1. Acceleration sensor 17 and exhaust brake switch 1 detect the acceleration of the vehicle and output a signal when the acceleration exceeds a certain value.
The solenoid valve 12 is connected in parallel with the solenoid valve 19 that is activated when the valve 8 is turned on, and is activated by the respective detection signals. The electromagnetic clutch 10 is turned on and the supercharger 4 is driven by the output of the crankshaft 7. An exhaust shutter 22 is disposed in the exhaust passage 21 of the internal combustion engine 1, and when the exhaust brake switch 18 is turned on, a solenoid valve 19 opens and is driven to open and close by an air cylinder 23 through which air is introduced from an air tank 20. It is becoming more and more common.

Next, the effect will be explained.

When the rotation speed of the internal combustion engine 1 falls below a certain low speed value and/or when the load becomes above a certain value, the rotation speed sensor 15 and/or the load sensor 16 output a detection signal. In response to the detection signal, the electromagnetic clutch 10 is turned on, and the supercharger 4 is driven by the output of the crankshaft 7. At the same time, the electromagnetic valve 12 guides air from the air tank 20 to the air cylinder 13.
The air cylinder 13 is operated to close the on-off valve 6, which is always open. Therefore, the intake air that had previously been guided to the turbocharger 3 by bypassing the supercharger 4 via the intake passage 2a, the bypass passage 5, and the intake passage 2d is now transferred to the bypass passage 5.
It is led to the supercharger 4 through the intake passage 2b and compressed, and then the intake passage 2c,
From 2d onwards, turbocharger 3 will be activated.
Therefore, the intake air is compressed in two stages by the supercharger 4 and the turbocharger 3, and the intake efficiency is greatly improved. As a result, as shown in FIGS. 2 and 3, the output and smoke density are lower than when using only the conventional turbocharger 3 shown by the chain line.
In the case of using the turbocharger 3 and supercharger 4 as in this embodiment, as shown by the solid line,
Much improved.

Furthermore, when the acceleration of the vehicle becomes less than a certain value, the detection signal of the acceleration sensor 17 causes the
Stage compression is performed and the output of the internal combustion engine is improved, so
As a result, the acceleration performance during gear shifting of a vehicle equipped with, for example, a four-speed transmission shown in FIG.
The characteristic improves from a characteristic that has a step with each shift, as shown by the chain line, to a smooth, high acceleration characteristic as shown by the solid line.

Furthermore, when the exhaust brake switch 18 is turned on, the solenoid valve 19 is activated, the air in the air tank 20 is guided to the air cylinder 23, the air cylinder 23 is activated, the exhaust shutter 22 is closed, and the exhaust brake is applied. The output of the solenoid valve 19 performs two-stage compression as described above. At this time, due to the pumping loss of the internal combustion engine 1 and for driving the supercharger 4, the frictional horsepower increases by the hatched part compared to the case of only the turbocharger 3 shown by the chain line in FIG. 5, and becomes as shown by the solid line. become. As a result, the exhaust braking force is improved by the increase in frictional horsepower.

As explained above, an exhaust turbo supercharger and a positive displacement compressor are installed in series in the intake passage, and the intake air is compressed by both during low-speed rotation, which greatly improves the intake efficiency during low-speed rotation. improve.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention;
3 shows its output characteristic diagram, FIG. 3 shows its smoke density characteristic diagram, FIG. 4 shows its acceleration characteristic diagram during gear change, and FIG. 5 shows its exhaust braking force characteristic diagram. 2a to 2d...Intake passage, 3...Exhaust turbo supercharger, 4...Displacement compressor, 5...Bypass intake passage, 6...Opening/closing valve, 10...Electromagnetic clutch, 1
2, 19... Solenoid valve, 13, 23... Air cylinder, 15... Rotational speed sensor, 16... Load sensor, 17... Acceleration sensor, 22... Exhaust shutter.

Claims (1)

[Scope of utility model registration request] In a supercharging system for an internal combustion engine that is equipped with an exhaust turbo supercharger and a positive displacement compressor, the positive displacement compressor is provided on the upstream side of the intake passage, and the exhaust turbo supercharger is installed in series on the downstream side of the positive displacement compressor. A bypass passage is provided to bypass the positive displacement compressor, and is opened and closed by signals from the internal combustion engine's rotational speed sensor and load sensor, and is closed when the rotational speed becomes less than a predetermined value or the load exceeds a predetermined value. An on-off valve is provided in the bypass passage, and an exhaust shutter is provided in the exhaust passage from the exhaust turbo supercharger, and the exhaust shutter is driven to open and close by a solenoid valve that is activated when the exhaust brake switch is turned on. 1. A supercharging device for an internal combustion engine, comprising a drive means for closing an on-off valve to perform two-stage compression using an exhaust turbo supercharger and a positive displacement compressor when the valve is activated.