| 摘要 |
A valve arrangement (28) for use in limiting the pressure of fuel within an accumulator volume of an accumulator fuel system to a predetermined threshold level, the valve arrangement (28) comprising: a valve outlet (64, 66) for communication with a low pressure drain; a valve housing (30) provided with a valve housing bore for receiving fuel from the accumulator volume; and a valve member (50) having a closed position in which it is engaged with a valve seating (56) defined by the valve housing bore (48) to prevent fuel flow from the accumulator volume to the valve outlet (64, 66).The valve arrangement further comprises biasing means (70) for urging the valve member (50) towards the valve seating (56); a first restricted flow means (80) for restricting the flow of fuel between the accumulator volume and the valve outlet (64, 66) during a first stage of valve opening movement as soon as the valve member (50) is lifted from the valve seating (56); a second restricted flow means (82) effective during a second stage of valve opening movement which follows the first stage to provide a greater restriction than during the first stage; and a third restricted flow means (84) effective during a third stage of valve opening movement which follows the second stage to provide a variable restriction to fuel flow dependent on the extent of opening movement of the valve member (50).of the first, second and third restricted flow means (80, 82, 84) is defined between the valve member (50) and the valve housing bore (48). |
