Patent ID: 8074626
Filing Date: 2011-12-13
Classification: F02D

Abstract:
1. A charge control unit for controlling electricity charged to a piezo element, which is for actuating a backpressure control valve so as to control backpressure applied to a valve element for a fuel injection valve, wherein the backpressure control valve is configured to start to decrease the backpressure to actuate the valve element to open an injection port of the fuel injection valve when voltage of the electricity exceeds a threshold, the charge control unit comprising: a charge unit configured to increase the voltage by repeating increasing and decreasing a drive current, which is supplied to the piezo element, for a plurality of times for charging the piezo element; and a switching unit configured to alternate the increasing and the decreasing in the drive current such that the voltage exceeds the threshold in an intermediate period in a middle of a specific increasing period among a plurality of increasing periods, in each of which the drive current increases, wherein the specific increasing period is selected from the plurality of increasing periods depending on an operation of an internal combustion engine, and the specific increasing period is set to appear at an early timing in a case where the internal combustion engine is in a high-load operation compared with a late timing in a case of a low-load operation, wherein the charge unit includes: a determination unit configured to determine whether the internal combustion engine is in the high-load operation or the low-load operation; and a control unit configured to: i) select the specific increasing period from the plurality of increasing periods to cause the selected specific increasing period to appear at the early timing in response to determination of the determination unit that the internal combustion engine is in the high-load operation; and ii) select the specific increasing period from the plurality of increasing periods to cause the selected specific increasing period to appear at the late timing in response to determination of the determination unit that the internal combustion engine is in the low-load operation, wherein the early timing is earlier than the late timing.