JPS6157928B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a supercharged internal combustion engine that is equipped with a supercharger in its intake system that uses energy from exhaust gas to drive the engine, and in particular, in the case that the exhaust system has a catalyst device, the engine is designed to prevent deterioration in its purification performance. related to what was done.

[Conventional technology]

In a supercharged internal combustion engine that uses exhaust gas energy to drive a supercharger, the turbocharger turbine is connected to the upstream side of the exhaust system where the exhaust gas energy is large. Therefore, the catalyst device for exhaust gas purification is installed downstream of the supercharger turbine (see Japanese Patent Laid-Open No. 54-35516).

[Problems to be solved by the invention]

Therefore, even when the engine is cold, when there is no need to improve output with the turbocharger, or at low engine speeds, when there is insufficient exhaust gas energy to provide sufficient supercharging, the exhaust gas detours to the turbocharger turbine. flows into the catalytic converter, which causes a large drop in exhaust gas temperature.
There is a possibility that the purification ability of the catalyst device cannot be fully demonstrated.

[Means to solve the problem]

The present invention was made in view of these circumstances, and includes a bypass passage that bypasses the supercharger turbine in the exhaust system, as well as a switching valve, which switches only in the region of a predetermined rotation speed or higher when the engine is warmed up. The valve guides exhaust gas to the turbocharger side to drive the engine, and when the engine is otherwise cold or warm, even when the engine is warm, the exhaust gas is introduced directly to the catalyst device through the bypass passage using the switching valve, and the catalyst device is activated. To provide an internal combustion engine with a supercharger that prevents deterioration of purification performance due to

【Example】

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, reference numeral 1 denotes an air cleaner, and this air cleaner 1 communicates with a carburetor 3 via an intake passage 2 for natural intake. The carburetor 3 communicates with the suction side of the engine body 5 via a suction pipe 4. Further, the air cleaner 1 communicates with the intake passage 2 through intake passages 6 and 6' for supercharging, and the compressor 7a side of the supercharger 7 is configured to communicate between the intake passages 6 and 6'. A switching valve 8 is provided at the connection portion between the pumps 2 and 6 so as to automatically switch the switch depending on whether or not supercharging is provided. Exhaust pipe 9 from engine body 5
is connected to the turbine 7b side of the supercharger 7, and then to the catalyst device 10 and the muffler 11. In such a configuration, a bypass passage 12 is provided at a location near the catalyst device 10 of the exhaust pipe 9 so as to bypass the turbine 7b of the supercharger 7, and the bypass passage 12 is switched to a branch part from the exhaust pipe 9. A valve 13 is provided. In addition, a solenoid valve 1 having one side open to the atmosphere and the other side connected to a negative pressure tank 16 is provided.
A passage 14 from 5 is connected to a diaphragm actuator 17, and a link mechanism 18 operates to switch the switching valve 13 so as to shut off the exhaust pipe 9 or the bypass passage 12 by the negative pressure or atmospheric pressure of the actuator 17. The electromagnetic valve 15 has a battery 19, a key switch 20, a water temperature switch 21, and a vehicle speed switch 22 connected in series to the coil side, and when the engine is warmed up, the water temperature switch 21 is turned on, and when the rotation speed exceeds a predetermined number, the vehicle speed switch 22 is turned on. It works both when it is turned on and when it is not. Since the present invention is configured in this way, the water temperature switch 21 is turned off when the engine is cold, and the vehicle speed switch 22 is turned off when the engine is running at low speeds, so that in both of these cases, the solenoid valve 15 is turned off. It communicates with the pressure tank 16 side. Therefore, actuator 17
Negative pressure acts on the selector valve 13 to switch the exhaust pipe 9 to a state where the exhaust port side is directly connected to the catalytic converter 10 via the bypass passage 12. The feeder 7 is disconnected and does not drive, and the exhaust gas is immediately transferred to the catalyst device 1.
It goes to 0 and is purified. On the other hand, since the supercharger 7 is not driven, no supercharging pressure is generated, so the switching valve 8 operates to open the intake passage 2, and the intake passage 2 opens the compressor 7a of the supercharger 7.
Air is naturally aspirated without any resistance. Next, when the engine speed reaches a predetermined speed while the engine is warmed up, the water temperature and vehicle speed switches 21 and 22 are both turned on and the solenoid valve 15 is opened to the atmosphere, so that the actuator 17 reaches atmospheric pressure and switches. The bypass passage 12 is shut off by the valve 13, and exhaust gas is introduced into the turbine 7b of the supercharger 7 to drive it. Therefore, compressor 7 of supercharger 7
A supercharging is performed, and this supercharging pressure causes the switching valve 8 to switch to the air cleaner side, thereby preventing backflow to the air cleaner 1.

【Effect of the invention】

As described above, according to the present invention, when supercharging is not required when the engine is cold, or when supercharging is insufficient at low rotation speeds even when the engine is warm, exhaust gas is transferred to the turbine 7b of the supercharger 7 through the bypass passage 12. Since the exhaust gas bypasses the exhaust gas and immediately enters the catalyst device 10 and is purified in a state where the exhaust gas temperature is high, in this case, the purification ability of the catalyst is fully utilized and the purification process can be carried out effectively. Further, the water temperature switch 21 and the vehicle speed switch 22 can accurately determine the engine operating state and perform accurate control.

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an embodiment of a supercharged internal combustion engine according to the present invention. 2...Intake passage for natural intake, 6, 6'...Intake passage for supercharging, 7...Supercharger, 7a...Compressor, 7b...Turbine, 9...Exhaust pipe, 10...
Catalyst device, 12...Bypass passage, 13...Switching valve, 15...Solenoid valve, 16...Negative pressure tank, 17
... Actuator, 18 ... Link mechanism, 21
...Water temperature switch, 22...Vehicle speed switch.

Claims (1)

[Claims] 1 The compressor side of the supercharger is connected to the engine intake system, and the turbine side of the supercharger is connected to the engine exhaust system, and a catalyst device is provided downstream of the turbocharger turbine, and the engine exhaust system is connected to the compressor side of the supercharger. A bypass passage that bypasses the supercharger turbine is provided, and a switching valve equipped with a diaphragm actuator is provided, and the switching valve is switched to cut off the bypass passage only in a region of a predetermined rotation speed or higher when the engine is warmed up. An internal combustion engine with a supercharger, characterized in that it is configured to drive the supercharger.