Fluid controller

1 . A fluid controller for independent metering control, the fluid controller comprising:

spools for hydraulic actuators, wherein each of the hydraulic actuators moves bi-directionally in accordance with supply of a fluid thereto; and

a housing including:

spool holes that receive therein the respective spools;

a pump passage;

a tank passage; and

for each of the spools, a first supply/discharge passage and a second supply/discharge passage, wherein

at least one of the spools is a separated-type spool including a first spool and a second spool that are separated apart from each other in an axial direction of the separated-type spool,

the spool holes include a particular spool hole that receives therein the separated-type spool,

the first spool blocks the first supply/discharge passage from both the pump passage and the tank passage, or allows the first supply/discharge passage to communicate with one of the pump passage or the tank passage, to control a supply flow rate to or a discharge flow rate from one of the hydraulic actuators,

the second spool blocks the second supply/discharge passage from both the pump passage and the tank passage, or allows the second supply/discharge passage to communicate with the other one of the pump passage or the tank passage, to control the supply flow rate to or the discharge flow rate from the one of the hydraulic actuators,

the housing includes:

a first pilot chamber faced by an end surface of the first spool, the end surface being an end surface of an opposite side of the first spool from the second spool; and

a second pilot chamber faced by an end surface of the second spool, the end surface being an end surface of an opposite side of the second spool from the first spool,

a portion of the particular spool hole between the first spool and the second spool forms a third pilot chamber, and

the housing includes a pilot passage that communicates with the third pilot chamber,

the fluid controller further comprising:

a first solenoid proportional valve that outputs a first pilot pressure to the first pilot chamber;

a second solenoid proportional valve that outputs a second pilot pressure to the second pilot chamber; and

a third solenoid proportional valve that outputs a third pilot pressure to the third pilot chamber.

2 . The fluid controller according to claim 1 , wherein

all the spools are located parallel to each other in a particular direction, and

an opening, of the pilot passage, to the third pilot chamber is positioned away from a plane in the particular direction, the plane being orthogonal to the particular direction and passing through a center of the particular spool hole.

3 . The fluid controller according to claim 1 , wherein

the housing includes a recess that is recessed from the particular spool hole in a manner to have a pointy shape radially outward, and the pilot passage is connected to the recess.

4 . The fluid controller according to claim 1 , wherein

all the spools are located parallel to each other in a particular direction,

the pump passage extends in the particular direction,

the housing includes:

a bridge passage that surrounds the pump passage together with the particular spool hole and that is connected to the particular spool hole on both sides of the third pilot chamber; and

a communication hole through which the bridge passage and the pump passage communicate with each other,

the fluid controller comprises a load check valve that is mounted in the housing and that opens and closes an opening, of the communication hole, to the bridge passage, and

in a direction orthogonal to both the particular direction and the axial direction of the separated-type spool, the pilot passage is positioned on an opposite side of the pump passage from the load check valve.

5 . The fluid controller according to claim 4 , wherein

the housing includes a regeneration passage that is positioned on an opposite side of the particular spool hole from the load check valve, the regeneration passage being a passage to lead the fluid flowing from one of the first supply/discharge passage or the second supply/discharge passage into the particular spool hole to the other one of the first supply/discharge passage or the second supply/discharge passage, and

the pilot passage overlaps the regeneration passage as seen in the particular direction.

6 . The fluid controller according to claim 4 , wherein the third solenoid proportional valve is mounted to the housing at a position that is located on an opposite side of the particular spool hole from the load check valve.

7 . The fluid controller according to claim 1 , wherein the third solenoid proportional valve is mounted to the housing,

all the spools are located parallel to each other in a particular direction, and

the third solenoid proportional valve is positioned on a plane that is orthogonal to the particular direction and that passes through a center of the particular spool hole.

8 . The fluid controller according to claim 1 , wherein the third solenoid proportional valve is mounted to the housing,

all the spools are located parallel to each other in a particular direction, and

the third solenoid proportional valve is positioned away from a plane in the particular direction, the plane being orthogonal to the particular direction and passing through a center of the particular spool hole.

9 . The fluid controller according to claim 1 , wherein

the separated-type spool included in all the spools is a plurality of separated-type spools, and

all the spools further include an integrated-type spool that is positioned between the plurality of separated-type spools and that straddles the first supply/discharge passage and the second supply/discharge passage.

10 . The fluid controller according to claim 1 , wherein

all the spools are located parallel to each other in a particular direction,

the pump passage extends in the particular direction,

the housing includes:

a bridge passage that surrounds the pump passage together with the particular spool hole and that is connected to the particular spool hole on both sides of the third pilot chamber; and

a communication hole through which the bridge passage and the pump passage communicate with each other, and

in a direction orthogonal to both the particular direction and the axial direction of the separated-type spool, the pilot passage is positioned on an opposite side of a center of the particular spool hole from the bridge passage.