Rotary piston four-stroke internal combustion engine

#In a known rotary piston internal combustion engine of the type described in U.S. Pat. No. 3,791,145, in order to improve afterburning of unburned exhaust constituents, after cold starting and while running warm from the region under compression of the inner chamber of the engine, fresh gas is introduced into the exhaust gas reactor by way of a line provided for the purpose. At the same time, under the action of the compression pressure or in response to the angular position of the eccentric shaft of the engine, a valve arranged in the line is periodically opened. An additional shut-off means arranged in this line and responding to the operating temperature of the exhaust gas reactor is provided, shutting off the supply of fresh gas when the warm-up phase is ended and the exhaust gas reactor has reached a certain temperature. However, the diversion of fresh gas from the inner chamber entails a diminution of the quantity of available ignitable fresh gas inside the working chamber, and this means a sacrifice of power. Then if during the warm-up phase or shortly after a cold start, a high output demand is placed on the engine, the expected full power will not be available because the shut-off means influenced by the operating temperature of the exhaust gas reactor is still open, permitting withdrawal of frersh gas. The associated loss of charge and consequently power may have adverse effects especially when the engine is used for propulsion of a motor vehicle in road traffic.

#The object of the invention is to control the supply of fresh gas to the exhaust gas reactor in such a way that no impairment of the power of the engine in the cold starting and warm-up phases can occur, if there is an increased output demand.

#This object is accomplished, according to the invention, in that the valve is controlled by the negative pressure in the intake duct, so that the line is cleared above a certain amount of negative pressure and shut-off below that value.

#In the drawings:

#FIG. 1 is a schematic end elevational view, partly in section showing a rotary piston four-stroke internal combustion engine of trochoid type with means according to the invention for controlling supply of fresh gas to the exhaust gas reactor, schematically represented;

#FIG. 2 is a fragmentary sectional view of an intake duct near the throttle flap in FIG. 1;

#The rotary piston four-stroke internal combustion engine shown in FIG. 1 has a housing 1 composed of a shell 2 and two parallel end parts 3 together bounding an inner chamber 4 in which a polygonal piston 5 is rotatably arranged. In the housing 1, the piston 5 forms three working chambers, A, B, C of varying volume, in each of which a four-stroke process is carried out with corresponding phase displacement. For this purpose, the housing 1 is provided with an inlet passage 6 to supply air or fresh gas and an output passage 7 for ejection of burned gases. The inlet passage 6 is connected to an intake duct 8 and the outlet passage 7 to an exhaust gas reactor 9. A spark plug 10 is indicated in this embodiment by way of example by a conventionalized lightning bolt. From the region of the inner chamber 4 in which compression takes place, a line 12 leads by way of a valve 11 to the exhaust gas reactor 9, a check valve 13 being arranged in the line 12. The valve 11 is further connected to the intake duct 8 by a negative-pressure line 14 debouching downstream from the closed throttle flap 15 in intake duct 8. In the negative-pressure line 14, a magnetic valve 16 is provided, connected by way of a cable 17 to a temperature sensor 18 at the exhaust gas reactor. At the mouth of the line 12 into the exhaust gas reactor 9, a vibrator ignition 20 supplied by a spark transformer 19 may be arranged. The orifice 31 of line 12 is located at a point on end part 3 that is swept by the sealing pins 32. The sealing pins 32 thus briefly obstruct the orifice 31, avoiding communication between the compression working chamber A and the working chamber C, which would result in a loss of power.

#FIG. 2 shows a portion of the intake duct 8 into which downstream from the closed throttle flap 15 in the direction of the arrow 33, the negative-pressure line 14 opens. The throttle flap position 15' shown dotted indicates the approximate setting beyond which the idling or partial load range is exceeded and the orifice of the negative-pressure line 14 gets out of the region of negative pressure prevailing behind the throttle flap at 15'.

#The withdrawal of fresh gas or air to improve after-burning in the exhaust gas reactor then proceeds as follows. Immediately after a cold start of the engine, owing to the negative pressure prevailing in the inlet passage 6 when the throttle flap 15 is closed, the valve 11 is opened by way of the negative-pressure line 14, the slide 22 being lifted by the diaphragm 28 of the chamber 27, overcoming the force of spring 29. Then fresh gas flows from working chamber A which is in the compression phase, into the line 12 and passes by way of the check valve 13 into the exhaust gas reactor 9, thus providing for rapid heating and afterburning of unburned exhaust gas constituents in the reactor 9.