JPS603945Y2 - Rotary piston engine exhaust port cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust port cooling device for a rotary piston engine, particularly a rotary piston engine equipped with a catalyst device in the exhaust system.

It is generally well known that a rotary piston engine is equipped with a catalyst device (catalytic converter) in the exhaust system in order to purify the exhaust gas. It is also well known to cool the casing to an appropriate temperature by flowing cooling water through the cooling passage.

Conventionally, in such a rotary piston engine, the exhaust gas discharged from the exhaust port is kept as warm as possible to promote its re-combustion, and the high-temperature exhaust gas is introduced into a catalyst device to be purified. Accordingly, it has been proposed to purify exhaust gas, that is, to improve emission performance.

However, it has been found that if the catalyst in the above-mentioned catalyst device is exposed to high-temperature exhaust gas, its purification performance deteriorates significantly in a short period of time. However, there is a problem in that it accelerates the deterioration of the catalyst over time, which in turn leads to deterioration in emission performance.

Therefore, the present invention has been developed in view of this point, and is designed to actively cool the exhaust gas discharged from the exhaust port in the rotary piston engine as described above to an appropriate temperature using a method similar to the method for cooling the casing described above. In particular, when the exhaust gas temperature is low, that is, when the engine temperature is low, taking into consideration the deterioration of emission performance due to an increase in unburned gas, cooling of the exhaust gas is stopped, which leads to deterioration of emission performance. It is an object of the present invention to provide an exhaust port cooling device for a low-return piston engine that can improve the aging durability of a catalyst in a catalyst device without causing any damage.

That is, the present invention forms a cooling passage in a casing having a multi-arc inner circumferential surface, cools the casing by flowing cooling water into the cooling passage, and also provides cooling water in the exhaust passage downstream of the exhaust port of the casing. In a rotary piston engine equipped with a catalytic converter, an auxiliary cooling passage is provided in the casing or an auxiliary block attached to the casing near the exhaust port, and a control valve is provided in the auxiliary cooling passage, and the auxiliary cooling passage is provided only when the engine temperature is high. Cooling water is made to flow through the cooling passage.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

1 and 2, reference numeral 1 denotes a rotor housing 2 having a trochoidal (that is, multi-arc-shaped) inner circumferential surface 2a, and a side housing 3 (in the case of a multi-cylinder model, an interface 4 is a polygonal rotor that rotates planetarily within the casing 1 while its apex portion is in sliding contact with the inner circumferential surface 2a of the rotor housing 2. As the rotor 4 rotates, the inside of the casing 1 is divided into three working chambers 5, and each stroke of intake, compression, explosion, expansion, and exhaust is performed in sequence.

Further, 6 is an intake port opened in the side housing 3, 7 is an exhaust port opened in the rotor housing 2,
A cooling passage 8 is formed to axially penetrate the casing 1, that is, the rotor housing 2 and the side housing 3 (including the intermediate housing 3'), and a radiator 9 and a radiator 8 are provided at both ends of the cooling passage 8. A cooling water circulation path 11 with a water pump 10 interposed therebetween is connected, and the cooling water cooled by the radiator 9 is flowed through the cooling passage 8 by the water pump 10 to cool the casing 1 to an appropriate temperature, and the heat exchanged cooling water is recirculated. The water is configured to be refluxed to the radiator 9.

Reference numeral 12 denotes a bypass passage provided in parallel with the radiator 9, and a thermovalve 13 is provided at a branch of the bypass passage 12. By switching the thermovalve 13, the engine is warmed up when the engine is cold. The cooling water is configured to flow through the bypass passage 12 to promote cooling, while the cooling water is flowed through the radiator 9 to cool the engine after warming up the engine.

An auxiliary block 15 is integrally attached to the casing 1 in the vicinity of the exhaust port 7 and has an extended exhaust port 14 in the center that is continuous with the exhaust port 7. The exhaust port 16 of the piston engine is provided to extend the length of the exhaust port 16, and an auxiliary cooling passage 17 is formed adjacent to the outer periphery of the extended exhaust port 14 of the auxiliary block 15 and penetrates in the axial direction. The upstream and downstream ends of the auxiliary cooling passage 17 are connected to the cooling water circulation path 11, respectively, and a thermovalve 18 that detects the engine temperature and opens and closes is interposed near the upstream end of the auxiliary cooling passage 17. When the engine temperature is high, the thermovalve 18 is opened to allow cooling water to flow into the auxiliary cooling passage 17, while when the engine temperature is low, the thermovalve 18 is opened.
is configured to close and stop the flow of cooling water to the auxiliary cooling passage 17.

Note that 19 is a re-combustion chamber connected to the downstream end of the exhaust port 16, 20 is an exhaust passage connected to the downstream end of the re-combustion chamber 19, and a catalyst device (
A catalytic converter) 21 is provided.

Therefore, in the above embodiment, when the engine temperature is high, cooling water flows into the auxiliary cooling passage 17 by opening the thermovalve 18, so that the exhaust port 16
The high-temperature exhaust gas discharged from the catalytic converter is cooled to an appropriate temperature, reburned to some extent in the re-combustion chamber 19, and then introduced into the catalyst device 21 where it is purified. Therefore, catalyst device 2
It is possible to purify exhaust gas while preventing aging deterioration of the first catalyst.

On the other hand, when the engine temperature is low, the thermo valve 18
As the cooling water does not flow into the auxiliary cooling passage 17 due to the closing operation of After being re-burned, the unburned fuel is introduced into the catalyst device 21 to purify the unburned fuel, so that the emission performance at low temperatures of the engine will not be deteriorated.

In the above embodiment, the casing 1 and the auxiliary block 15 were formed separately, but it is possible to form them both integrally, provide an exhaust port that passes through them in series, and provide an auxiliary cooling passage close to the exhaust port. Of course, it is also possible to provide an auxiliary cooling passage in the vicinity of the exhaust port in the casing of the rotary piston engine or in the auxiliary block attached to the casing.

As explained above, according to the present invention, an auxiliary cooling passage is provided in the casing of a rotary piston engine or an auxiliary block attached to the casing near the exhaust port, and a control valve is provided in the auxiliary cooling passage. By allowing the cooling water to flow into the auxiliary cooling passage only occasionally, it is possible to improve the aging deterioration of the catalyst of the catalyst device without deteriorating the emission performance.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, with FIG. 1 being a schematic longitudinal sectional side view and FIG. 2 being a schematic explanatory view. 1...Casing, 2...Rotor housing, 2a...Inner peripheral surface, 3...Side housing, 3'...Intermediate Eight housing, 4... Rotor, 5... Working chamber, 6... Intake port, 7. Bent/exhaust port, 8... Cooling passage, 9 ...Radiator, 10...Water pump, 11...
Cooling water circulation path, 12... bypass passage, 13.
...Thermo valve, 14...Extension exhaust port, 15...Auxiliary block, 16...
・Exhaust port, 17... Auxiliary cooling passage, 18.
...Thermo valve, 19... Re-combustion chamber,
20... Exhaust passage, 21... Catalyst device.

Claims (1)

[Scope of utility model registration request] The rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary rotary vehicle having a cooling passage formed in a casing having a multi-arc inner circumferential surface, cooling water flowing in the cooling passage to cool the casing, and equipped with a catalytic converter in the exhaust passage downstream of the exhaust port of the said casing. In a piston engine, an auxiliary cooling passage is provided in the casing or an auxiliary block attached to the casing near the exhaust port, and a control valve is provided in the auxiliary cooling passage, so that cooling is carried out in the auxiliary cooling passage only when the engine temperature is high. An exhaust port cooling device for a rotary piston engine characterized by allowing water to flow through it.