Hydraulic machine
A hydraulic machine is provided. A boom actuator includes a large chamber and a small chamber. A recovery unit receives fluid discharged from the large chamber and then recovers energy. A recovery line connects the large chamber and the recovery unit. An accumulator is connected to the recovery line. A jack-up assist line connects the accumulator and the small chamber. A jack-up assist valve is disposed on the jack-up assist line to block flow of fluid from the accumulator to the small chamber in a first position and allow the flow of fluid from the accumulator to the small chamber in a second position. A controller controls movement of the jack-up assist valve. The controller may determine whether or not the hydraulic machine is in a jack-up condition, and when the hydraulic machine is determined to be in the jack-up condition, moves the jack-up assist valve to the second position.
1. A hydraulic machine comprising:
a boom actuator comprising a large chamber and a small chamber;
a recovery unit configured to receive fluid discharged from the large chamber and then recover energy;
a recovery line connecting the large chamber and the recovery unit;
an accumulator connected to the recovery line;
a jack-up assist line connecting the accumulator and the small chamber;
a jack-up assist valve disposed on the jack-up assist line to block flow of fluid from the accumulator to the small chamber in a first position and allow the flow of fluid from the accumulator to the small chamber in a second position; and
a controller configured to control movement of the jack-up assist valve,
wherein the controller is configured to:
determine whether or not the hydraulic machine is in a jack-up condition; and
when the hydraulic machine is determined to be in the jack-up condition, move the jack-up assist valve to the second position.
2. The hydraulic machine of claim 1 , further comprising a first sensor configured to measure a pressure in the accumulator,
wherein the controller controls movement of the jack-up assist to the second position such that the greater a value obtained by subtracting a pressure in the small chamber from the pressure in the accumulator measured by the first sensor is, the smaller the amount of the movement of the jack-up assist valve to the second position is.
3. The hydraulic machine of claim 1 , further comprising a first operator input device by which an operator-desired operating speed of the boom actuator is input,
wherein the controller controls movement of the jack-up assist valve to the second position such that the higher the operator-desired operating speed of the boom actuator, the greater the amount of the movement of the jack-up assist valve to the second position is.
4. The hydraulic machine of claim 1 , wherein the controller determines that the hydraulic machine is in the jack-up condition when a load pressure applied to the large chamber by a load is equal to or less than a threshold value.
5. The hydraulic machine of claim 4 , wherein the threshold value is in a range of 0 to 3 bars.
6. The hydraulic machine of claim 4 , wherein the load pressure is Pa−Pb/(Aa/Ab),
where Pa is pressure in the large chamber measured by a second sensor, Pb is pressure in the small chamber measured by a third sensor, Aa is an area of the large chamber, and Ab is an area of the small chamber.