Patent ID: 8652007

Claim:
A pressure accumulation system, which is applied to an internal combustion engine in which an exhaust shut-off valve is provided in an exhaust path, the exhaust shut-off valve being able to switch between a fully-closed position where the exhaust path is closed and a fully-opened position where the exhaust path is opened, the pressure accumulation system comprising: a pressure accumulation container in which a pressurized gas can be accumulated, the pressure accumulation container being configured to introduce gas from the exhaust path on an upstream side of the exhaust shut-off valve, the pressure accumulation container being configured to supply the gas to the exhaust path on the upstream side of the exhaust shut-off valve, the pressurized gas being accumulated in the pressure accumulation container by increasing a pressure in the exhaust path on the upstream side of the exhaust shut-off valve; a pressure value obtaining device configured to obtain a pressure value in the exhaust path on the upstream side of the exhaust shut-off valve or a pressure value in the pressure accumulation container; a pressure adjustment device configured to adjust the pressure value in the exhaust path on the upstream side of the exhaust shut-off valve; and a control device for controlling an operation of the pressure adjustment device based on the pressure value obtained by the pressure value obtaining device such that the pressure value in the exhaust path on the upstream side of the exhaust shut-off valve is restricted to a prescribed exhaust pressure upper limit value or less when the gas is accumulated in the pressure accumulation container, wherein the control device first increases the pressure value in the exhaust path on the upstream side of the exhaust shut-off valve to the exhaust pressure upper limit value when the gas is accumulated in the pressure accumulation container, and the control device controls the operation of the pressure adjustment device such that the pressure value in the exhaust path on the upstream side of the exhaust shut-off valve changes within a prescribed pressure range whose upper limit value is the exhaust pressure upper limit value, the gas is accumulated in the pressure accumulation container until a pressure in the pressure accumulation container reaches a prescribed target pressure, and a value that is lower than the exhaust pressure upper limit value and is greater than or equal to the target pressure is set to a lower limit value of the prescribed pressure range.