Patent GB-1527748-A (GB)
Title: Air supply system for the inlet manifold of an internal combustion engine
IPC: F02M23/08
Filed: 1975-12-18
Abstract: 1527748 Controlling extra air to IC engine inlet manifold W O LIEUWEN 18 Dec 1975 [18 Dec 1974] 51881/75 Heading F1B A system for controlling the supply of air to an inlet manifold 1 of an I.C. engine at a position downstream of a carburetter throttle valve 3, comprises a valve arranged in an air supply channel, an electromagnet connected to actuate the valve and a switch connected to the electromagnet to control energization thereof the switch being adapted to operate in response to fluid-pressure variations. A pressure sensitive switch 16 responsive by way of line 27 to the pressure just upstream of the throttle valve 3 has a contact 25 connected to a main coil 41 via a pulse switch 42 and a contact 24 connected to an auxiliary coil via a pulse switch 43. A pressure sensitive switch 17 responsive by way of line 40 to manifold pressure has a contact 38 connected to supply a pulse to pulse switch 42 and a contact 37 connected to supply a pulse to pulse switch 43. Each pulse switch, when it receives a pulse, switches from its open to its closed position or vice versa depending upon whether it is initially closed or open. Energization of main coil 41 acts on an armature formed by a slide 8 to completely open passage in a stud 13 and allow air to enter the inlet manifold 1 via tubes 12 and 14. Energization of auxiliary coil 45 acts on an armature 47 to open the passage partly, the opening depending on the position of an adjustable stop 49. At normal idling speed the switches 16 and 17 are adjusted so that the disc 23 engages contact 25 and the disc 36 is just free of contact 38. Slight opening of the throttle valve causes disc 23 to make with contact 24 so that the auxiliary coil 48 is energized partly opening the passage through stud 13. Further opening of the throttle valve 3 causes the disc 36 to move up to engage contact 37 as a result of which a pulse is applied to the pulse switch 43 thereby de-energizing the auxiliary coil 48, cutting off the additional air to the manifold. When the throttle valve 3 is closed during normal speed operation of the engine, e.g. to change gear or to achieve engine braking, the disc 23 engages contact 25 to connect current to the pulse switch 42 and the disc 36 makes with contact 38 to produce a pulse to pulse switch 42 to energize the main coil 41 to open the passage in stud 13. While the disc 23 remains in contact with the contact 25 the coil 41 is energized, even if an increase in manifold pressure breaks the contact between the disc 36 and the contact 38, since no further pulse is applied to the pulse switch 42 to open it. To prevent the engine from cutting out, a pulse is supplied to the pulse switch 42 by an electronic system when the engine speed falls to a preset value, so that the coil 41 is de-energized and the extra air supply to the inlet manifold is cut off. The pulse from the electronic system is also used to energize the coil 48 during idling operation. At high engine speeds, e.g. above 3500 to 4000 r.p.m., an electronic circuit supplies current to the pulse switch 43 so that the auxiliary coil 48 is energized to partly open the passage in the stud 13. In order to provide an increased flow of additional air into the manifold by way of the passage in the stud 13 as the engine speed increases further, a second auxiliary coil (52), Fig. 5 (not shown), may be provided. More than two auxiliary coils may be provided which are energized one after another as engine speed increases to provide a gradually increased air supply to the manifold. In another embodiment, Fig. 6 movable pistonlike bodies 57, 59 are responsive to the manifold pressure which is communicated to the space between them to influence their positions and thereby the position of a rod 58 to provide an adjustable stop means for the armature 47. Characteristics of springs 60, 62, 63 are chosen so that when the engine is operated with slightly opened throttle, the piston like body 57 limits downward movement of the armature 47. For lower manifold pressures, the head of rod 58 is raised above the body 57 and limits the downward movement of the armature 47. At higher manifold pressures (i.e. with greater throttle opening), the body 59 is urged further downwards and the body 57 acting as a stop for the armature 47 is moved downwards so that the more the inlet manifold pressure increases the greater is the distance through which the slide 8 can be displaced and the larger will be the passage opened for the additional supply of air to the manifold.