Control valve

1. A control valve comprising:

a main channel;

a channel cross section adjustment spool installed in a middle of the main channel to increase and reduce a channel cross section;

a downstream side branching channel that branches from the main channel on a downstream side of a position of the channel cross section adjustment spool;

a communication channel through which oil is fed from the downstream side branching channel toward the channel cross section adjustment spool;

a channel open and close spool installed between the downstream side branching channel and the communication channel to allow and block communication between the downstream side branching channel and the communication channel;

a channel open and close valve installed in a middle of the communication channel; and

an upstream side branching channel that branches from the main channel on an upstream side of the position of the channel cross section adjustment spool to supply a hydraulic pressure to the channel open and close spool,

wherein, in a low rotation speed region of an engine, the channel open and close valve blocks the communication channel to maximize a channel cross section of the main channel,

in a medium rotation speed region of the engine, the channel open and close spool allows the communication between the downstream side branching channel and the communication channel, and the channel open and close valve allows the communication channel to communicate to slide and move the channel cross section adjustment spool in a direction in which the channel cross section of the main channel is reduced, and

in a high rotation speed region of the engine, the channel open and close spool blocks the communication between the downstream side branching channel and the communication channel to maximize the channel cross section of the main channel.

2. A control valve comprising:

a main channel;

a channel cross section adjustment spool installed in a middle of the main channel;

a downstream side branching channel that branches from the main channel on a downstream side of a position of the channel cross section adjustment spool;

a communication channel which is in communication with the downstream side branching channel and through which oil is fed to the channel cross section adjustment spool;

a channel open and close valve installed in a middle of the communication channel to allow and block communication of the communication channel; and

an upstream side branching channel that branches from the main channel on an upstream side of the position of the channel cross section adjustment spool to supply a hydraulic pressure to the channel open and close spool,

wherein the channel open and close spool blocks communication between the downstream side branching channel and the communication channel as a hydraulic pressure in the upstream side branching channel increases,

the channel open and close valve allows the communication channel to communicate as a hydraulic pressure in the downstream side branching channel increases, and

the channel cross section adjustment spool is elastically biased in such a manner as to maximize a channel cross section of the main channel, and moves in such a manner that the channel cross section is reduced as a hydraulic pressure from the communication channel increases.

3. The control valve according to claim 1 , wherein a hydraulic pressure needed for the channel open and close valve to allow the communication channel to communicate is set lower than a hydraulic pressure needed for the channel open and close spool to block the communication between the downstream side branching channel and the communication channel.

4. The control valve according to claim 1 , wherein a drain channel is provided between a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed and a channel open and close valve chamber in which the channel open and close valve is installed,

a discharge channel is formed in the channel open and close valve chamber, and

the drain channel and the discharge channel are allowed to communicate with each other when the channel open and close valve blocks the communication channel.

5. The control valve according to 1 , wherein a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed is constituted by a main chamber portion and a sub-chamber portion which are orthogonal to the main channel, and

the channel cross section adjustment spool reciprocates between the main chamber portion and the sub-chamber portion in such a manner as to traverse the main channel.

6. The control valve according to claim 2 , wherein a hydraulic pressure needed for the channel open and close valve to allow the communication channel to communicate is set lower than a hydraulic pressure needed for the channel open and close spool to block the communication between the downstream side branching channel and the communication channel.

7. The control valve according to claim 2 , wherein a drain channel is provided between a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed and a channel open and close valve chamber in which the channel open and close valve is installed,

a discharge channel is formed in the channel open and close valve chamber, and

the drain channel and the discharge channel are allowed to communicate with each other when the channel open and close valve blocks the communication channel.

8. The control valve according to claim 3 , wherein a drain channel is provided between a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed and a channel open and close valve chamber in which the channel open and close valve is installed,

a discharge channel is formed in the channel open and close valve chamber, and

the drain channel and the discharge channel are allowed to communicate with each other when the channel open and close valve blocks the communication channel.

9. The control valve according to claim 2 , wherein a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed is constituted by a main chamber portion and a sub-chamber portion which are orthogonal to the main channel, and

the channel cross section adjustment spool reciprocates between the main chamber portion and the sub-chamber portion in such a manner as to traverse the main channel.

10. The control valve according to claim 3 , wherein a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed is constituted by a main chamber portion and a sub-chamber portion which are orthogonal to the main channel, and

the channel cross section adjustment spool reciprocates between the main chamber portion and the sub-chamber portion in such a manner as to traverse the main channel.

11. The control valve according to claim 4 , wherein a channel cross section adjustment spool chamber in which the channel cross section adjustment spool is installed is constituted by a main chamber portion and a sub-chamber portion which are orthogonal to the main channel, and

the channel cross section adjustment spool reciprocates between the main chamber portion and the sub-chamber portion in such a manner as to traverse the main channel.