GB1427981A - Internal combustion engines having fuel injection - Google Patents

Abstract

1427981 Throttle valve by-pass passage valves ROBERT BOSCH GmbH 7 March 1973 [8 March 1972] 11173/73 Heading F1B Fuel injection I.C. engine has a throttle valve in its inlet manifold for controlling the engine speed and a by-pass passage around the throttle valve in which is a further valve comprising a blade member pivotally mounted to move in a plane transverse to the passage and about an axis eccentric relative to the passage, the blade being moved by the action of a bi-metal spring, to a position in which it at least partially blocks the passage, in dependence upon the temperature of the spring. The engine has electromagnetically operated injection valves in the inlet manifold, one per cylinder, close to the inlet valves. A transistorized circuit device 25 controls the period of time during which fuel is injected, in response to the inlet manifold vacuum, which is detected by a diaphragm in housing 41. The by-pass passage consists of pipes 51 and 52 and a blade 55 which is movable between their opposing ends. Blade 55 is mounted on pivot pin 56 and biased by a tension spring 67 so that projection 66 of the blade bears against free end 65 of bi-metal spring 60, the other end of which is fixed in terminal block 61. The ends of electrical heater winding 64 are connected to terminal pins 62 in block 61. When spring 60 is cold, blade 55 is in a position such that window 83 is in line with the pipes. As the spring temperature increases, the spring bends away from projection 66 and tension spring 67 pivots the blade to move the window out of alignment with the pipes. Provision is made for adjusting the initial position of the plate 55, by mounting the pivot pin 56 in a support plate 70, part 72 of which has slot 73 through which passes locking screw 74. A narrow sealing lip 79 is formed on the support plate 70 and the plate 55 is drawn against this lip by the manifold depression. In a first modification, Figs. 4 and 5 (not shown) the support plate is omitted and the pivot pin 56 is mounted in an end-plate which closes the open end of a sheet metal tube and housing which contain the bi-metal spring and plate 55. In a second modification Fig. 6, (not shown) a die cast aluminium casing is used, the pipes 51 and 52 are integral with the casing and project to the same side of the casing. A U-bend is provided to connect the ends of the pipes corresponding to the opposing ends in the previous embodiments. In a third modification, Figs. 7 and 8 (not shown) blade 55 is mounted in a plane which is parallel to the direction of movement of the bi-metal spring and a lug secured to the end of the spring projects into this plane to engage the part 66 of the blade 55. In a fourth modification, Fig. 9 (not shown) the tension spring 67 is omitted and the bi-metal spring is connected to the part 66 by a pivoted link. In a fifth modification, Figs. 10 and 11 (not shown), the construction closely resembles that of Figs. 2 and 3, but provision is made for rotating the block 61 holding the end of the bi-metal spring to set the initial posision of the plate 55 by altering the force exerted on it by the free end of the bi-metal spring. The Specification also states that the arrangement can be reversed so that as the temperature increases the force exerted by the bi-metal spring increases and the tension of the spring 67 is increased.