Patent GB-647957-A (GB)
Title: Improvements in spray carburettors
IPC: F02M1/10
Filed: 1947-08-07
Abstract: 647,957. Spray carburetters. CARTER CARBURETOR CORPORATION. Aug. 7, 1947, No. 21593. Convention date, July 25, 1940. [Class 7(iii)] A spray carburetter comprises yielding means to close a choke valve for starting means operated by an opening movement of the throttle valve beyond a first predetermined position to open the choke valve against the yielding means resilient means operatively associated with the throttle valve and operatively independent of the choke valve and a movable abutment arranged' to be moved to a position by the closing of the choke valve to co-operate with the resilient means to resist the opening of the throttle valve beyond a second predetermined less opened position thereof the resilient means being movable with relation to' the abutment after contact therewith by a further movement of the throttle valve beyond the second predetermined position whereby the resistance to throttle opening movement is decreased. In Fig. 1 a choke valve 2 is mounted on a shaft 3 which projects into a choke control housing 6 at one side of an intake conduit 1. The housing contains thermosensitive mechanism for closing the choke valve under cold starting conditions. Suitable automatic choke mechanism is described in Specification 472,090 referred to. At the lower part of the intake conduit is mounted a throttle valve 4 carried by a shaft 5 and a switch comprising a contact plate 11 and screws 12 which is controlled in such a manner that when the throttle valve is opened to its normal starting position, Fig. 3, the plate 11 engages the screws to energize the starter circuit. The switch mechanism is described in detail in Specification 531,244, [Group XXXV]. When the choke valve is closed the throttle valve closing is limited by a screw 19 engaging a portion 26 of a cam 16 which is loosely mounted on the shaft 3. Cam 16 is resiliently connected to plate 15 and the choke valve by means of an axial finger 50 on the plate which projects between a radial part 51 on the cam and one end 52 of a torsion spring which is secured at its other end to the cam 16. As the choke valve is opened the cam 16 is swung counterclockwise towards the position shown in Fig. 1 in which a recessed portion 27 of the cam is opposite the screw 19. The screw is carried by a bell-crank 18 mounted on a pintle 17 and the bell-crank has a laterally projecting pin 20 which is slidably received in a slot 22 in a link 21 which at its lower portion is pinned at 23 to a crank 24 rigid with the throttle shaft 5. An inwardly projecting lip 28 on the upper portion of the link 21 provides for positively opening the choke by substantially full opening movement of the throttle valve the lip engaging a portion 29 of a plate 15 fixed to the choke shaft 3. An operator may be unable to distinguish in operation of a throttle pedal between the starting position of the throttle valve, Fig. 3, and the unloading position in which the choke valve is forced open. A positive indication is given by the mechanism now to be described. Loosely pivoted on the pintle 17 is a weighted lever 31 which is normally maintained in an inoperative position due to its weighted lower portion. A finger 32 on the lever has an inclined upper edge 33 positioned to be engaged by a lug 34 on the choke plate 15 when the choke is closed to rotate the lever 31 slightly in a clockwise direction. Pivotally mounted on the link 21 is a finger 35 urged in a counterclockwise direction by a spring 36. The finger has an inclined upper edge 37 which is disposed to engage an outwardly projecting pin 38 at the lower extremity of the lever 31 when the lever is moved to its operative position and the throttle valve is opened to its starting position. Upon slight additional opening movement the edge 37 on the finger 35 operates by cam effect upon the pin 38 to rotate the lever 31 in a clockwise direction and free the plate 15 and choke valve from the finger 32. Further opening movement of the throttle valve is resisted by the spring 36. Continued opening movement of the throttle valve against this resistance causes the finger 35 to be forced clockwise through camming action against the pin 38. Ultimately the pin will be forced between the link 21 and the inner edge 39 of the finger and sensible resistance to the opening of the throttle valve is no longer applied.