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A range switching device for switching supply and non-supply of a source pressure based on a hydraulic pressure from a hydraulic pressure generating source to a parking device, the parking device being switched into a parking release state while the source pressure is supplied thereto and being swit

A range switching device for switching supply and non-supply of a source pressure based on a hydraulic pressure from a hydraulic pressure generating source to a parking device, the parking device being switched into a parking release state while the source pressure is supplied thereto and being switched into a parking state while the source pressure is not supplied thereto.

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1. A range switching device for switching supply and non-supply of a source pressure based on a hydraulic pressure from a hydraulic pressure generating source to a parking device, the parking device being switched into a parking release state while the source pressure is supplied thereto and being s

1. A range switching device for switching supply and non-supply of a source pressure based on a hydraulic pressure from a hydraulic pressure generating source to a parking device, the parking device being switched into a parking release state while the source pressure is supplied thereto and being switched into a parking state while the source pressure is not supplied thereto, the range switching device comprising: a solenoid valve that pressure-regulates the source pressure to output a control pressure; anda parking switching valve, wherein:the parking switching valve includes a first spool that is movable to a first position and to a second position,a biasing member that is disposed on one end side of the first spool and biases the first spool to the first position,a second spool that is movable to a third position and to a fourth position,a first input port to which the source pressure is supplied,a first output port that is blocked from communication with the first input port while the first spool is in the first position and is in communication with the first input port while the first spool is in the second position,a second input port that is in communication with the first output port,a second output port that is in communication with the parking device, is in communication with the second input port while the second spool is in the third position, and is blocked from communication with the second input port while the second spool is in the fourth position,a third input port that is in communication with the first output port to receive input of the source pressure so that the second spool is biased to a direction of the fourth position by the source pressure, anda control port to which the control pressure is input so as to apply the control pressure output from the solenoid valve to other end side of the first spool and one end side of the second spool,in a case in which the control pressure is input to the control port and is applied to the other end side of the first spool and the one end side of the second spool, the first spool is moved to reach the second position against biasing force of the biasing member and the second spool is moved to reach the third position, so that the source pressure is supplied to the parking device through the second output port, andin a case in which the control pressure is not input to the control port and the first spool sticks in the second position, the second spool is moved to reach the fourth position by the source pressure supplied to the third input port, so that the source pressure is not supplied to the parking device. 2. The range switching device according to claim 1, wherein the second spool includes a first land portion, a second land portion, and a third land portion sequentially from the one end side of the second spool, and is configured so that a pressure receiving area on one end surface of the third land portion to which the source pressure input to the third input port is applied is smaller than a pressure receiving area on other end surface of the second land portion to which the source pressure is applied, and so that a difference between the pressure receiving area on the other end surface of the second land portion and the pressure receiving area on the one end surface of the third land portion is smaller than a pressure receiving area on one end surface of the first land portion to which the control pressure input to the control port is applied. 3. The range switching device according to claim 2, wherein the first spool and the second spool form a gap between other end surface of the first spool and one end surface of the second spool when other end portion of the first spool and one end portion of the second spool are in contact with each other, by a projecting portion provided on at least one of the other end portion of the first spool and the one end portion of the second spool, and apply the control pressure that is supplied to the control port to the other end surface of the first spool and the one end surface of the second spool through the gap. 4. The range switching device according to claim 3, wherein the control port are provided in two positions, which are a position that is opposed to the gap formed when the first spool is in the first position and the second spool is in the third position respectively and a position that is opposed to the gap formed when the first spool is in the second position and the second spool is in the fourth position respectively. 5. The range switching device according to claim 4, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 6. The range switching device according to claim 2, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 7. The range switching device according to claim 3, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 8. The range switching device according to claim 1, wherein the first spool and the second spool form a gap between other end surface of the first spool and one end surface of the second spool when other end portion of the first spool and one end portion of the second spool are in contact with each other, by a projecting portion provided on at least one of the other end portion of the first spool and the one end portion of the second spool, and apply the control pressure that is supplied to the control port to the other end surface of the first spool and the one end surface of the second spool through the gap. 9. The range switching device according to claim 8, wherein the control port are provided in two positions, which are a position that is opposed to the gap formed when the first spool is in the first position and the second spool is in the third position respectively and a position that is opposed to the gap formed when the first spool is in the second position and the second spool is in the fourth position respectively. 10. The range switching device according to claim 9, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 11. The range switching device according to claim 8, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 12. The range switching device according to claim 1, wherein, in a case in which the first spool sticks in the second position and the control pressure is input to the control port, the second spool is moved to reach the third position by the control pressure supplied to the control port and the source pressure is supplied to the parking device through the second output port. 13. A hydraulic control system for a transmission having a parking device, the hydraulic control system comprising: a source that supplies source pressure;a parking cylinder connected to the parking device, the parking cylinder having a parking side, a parking release side and a biasing member disposed on the parking side;a first valve having: a first input port that is in communication with the source,a first output port, and a first spool for selectively allowing communication between the first input port and the first output port; anda second valve having: a second input port that is in communication with downstream of the first valve,a second output port that is in communication with the parking release side of the parking cylinder, anda second spool that is movable between a parking release state and a parking state,wherein the second spool allows communication between the second input port and the second output port when in the parking release state and prohibits communication between the second input port and the second output port when in the parking state, andwherein the first spool closes the first input port in a first position of the first spool so as to block a supply of the source pressure and block communication between the first input port and the first output port. 14. The hydraulic control system according to claim 13, further comprising a first solenoid that is able to move both the first spool and the second spool. 15. The hydraulic control system according to claim 14, wherein the first solenoid is a normally-closed type. 16. The hydraulic control system according to claim 14, wherein after the source pressure is applied to the parking cylinder and the parking device is in the parking release state, a position of a parking rod can be switched between a position in which the parking rod is fixed and a position in which the parking rod is unlocked from this fixation by the first solenoid for locking. 17. The hydraulic control system according to claim 13, further comprising: a solenoid that pressure-regulates the source pressure to output a control pressure, wherein:the first spool is movable to the first position and to a second position,a biasing member is disposed on one end side of the first spool and biases the first spool to the first position,the second spool is movable to a third position and to a fourth position,the first output port is blocked from communication with the first input port while the first spool is in the first position and is in communication with the first input port while the first spool is in the second position,the second input port is in communication with the first output port,the second output port is in communication with the second input port while the second spool is in the third position, and is blocked from communication with the second input port while the second spool is in the fourth position,the second valve includes a third input port that is in communication with the first output port to receive input of the source pressure so that the second spool is biased to a direction of the fourth position by the source pressure, andthe hydraulic control system includes a control port to which the control pressure is input so as to apply the control pressure output from the solenoid to other end side of the first spool and one end side of the second spool,in a case in which the control pressure is input to the control port and is applied to the other end side of the first spool and the one end side of the second spool, the first spool is moved to reach the second position against biasing force of the biasing member and the second spool is moved to reach the third position, so that the source pressure is supplied to the parking device through the second output port, andin a case in which the control pressure is not input to the control port and the first spool sticks in the second position, the second spool is moved to reach the fourth position by the source pressure supplied to the third input port, so that the source pressure is not supplied to the parking device.