Split type internal combustion engine

Claim 1

An internal combustion engine comprising: (a) first and second cylinder units each including at least one cylinder; (b) an intake manifold having therein a throttle valve, said intake manifold being divided downstream of said throttle valve into first and second intake passages respectively communicating with said first and second cylinder units, said intake manifold second intake passage having therein a stop valve near its entrance; (c) an exhaust passage; (d) an EGR passage connected from said exhaust passage to said intake manifold second intake passage for recirculating engine exhaust gases into said intake manifold second intake passage, said EGR passage having therein an EGR valve; (e) control means for providing a control signal and for disabling said second cylinder unit when the engine load is below a predetermined value; (f) valve drive means responsive to the control signal from said control and disabling means for closing said stop valve and opening said EGR valve, said valve drive means adapted to prevent the simultaneous opening of both of said stop and EGR valves and including: (1) a first vacuum source; (2) a second vacuum souce; (3) a pressure source whose pressure is higher than that of the first and second vacuum sources; (4) a first valve actuator having a working chamber; (5) a conduit for connecting said working chamber to said first vacuum source through a restriction orifice; (6) said first valve actuator being operable to close said EGR valve when said first valve actuator working chamber is communicated with said pressure source and to open when said first valve actuator working chamber is communicated with said first vacuum source through said restriction orifice; (7) a second valve actuator having a working chamber, said second valve actuator being operable to open said stop valve when said second valve actuator working chamber is communicated with said pressure source and to close said stop valve when said second valve actuator working chamber is communicated with said second vacuum sources; (8) a first valve responsive to the control signal from said control and disabling means to communicate said first valve actuator working chamber with said first vacuum source through said restriction orifice, said first valve being operable to communicate said first valve actuator working chamber with said pressure source in the absence of the control signal; (9) a second valve responsive to the control signal from said control and disabling means to communicate said second valve actuator working chamber with said second vacuum source, said second valve being operable to communicate said second valve actuator working chamber with said pressure source in the absence of the control signal; (10) a conduit connected from said first valve actuator working chamber to said second valve actuator working chamber, said conduit having therein a check valve for permitting flow from said second valve actuator working chamber to said first valve actuator working chamber but note vice versa.