Abstract:
A dual clutch device is provided with a first piston for engaging a first clutch by using hydraulic pressure supplied to a first hydraulic chamber and disengaging the first clutch by using a first spring, a second piston for engaging a second clutch by using hydraulic pressure supplied to a second hydraulic chamber and disengaging the second clutch by using a second spring, first supply lines for supplying hydraulic pressure to the first hydraulic chamber and a second hydraulic canceling chamber, second supply lines for supplying hydraulic pressure to the second hydraulic chamber and a first hydraulic canceling chamber, a first valve for allowing or blocking the hydraulic pressure supply to the first hydraulic chamber and the second hydraulic canceling chamber, and a second valve for allowing or blocking the hydraulic pressure supply to the second hydraulic chamber and the first hydraulic canceling chamber.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a dual clutch apparatus. 
       BACKGROUND ART 
       [0002]    Conventionally, there is known a dual clutch type transmission that is provided with a first input shaft connected to a first clutch that connects and disconnects power from an engine and a second input shaft connected to a second clutch that connects and disconnects the power from the engine, and performs a change of speed by alternately switching the first clutch and the second clutch (for example, see Patent Literature 1). 
         [0003]    In typical dual clutch type transmissions, one clutch corresponds to a gear train at odd numbered stages, and the other clutch corresponds to a gear train at even numbered stages. For this reason, on shifting up, for example, from a second gear to third gear, in a state in which a clutch for even, numbered stages is connected, and a synchronization mechanism for second gear is engaged, a synchronization mechanism for third gear is engaged. A clutch for odd numbered stages is connected with disconnection, of the clutch for even numbered stages. Thereby, a change of speed in which no torque loss occurs can be realized. 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent Literature 1: JP-T-2010-531417 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    In typical dual clutch apparatuses, a clutch is connected by supplying hydraulic pressure to the inside of a hydraulic chamber, releasing the hydraulic pressure from the inside of a hydraulic canceling chamber, and stroke-moving a piston to connect clutch plates under pressure. In addition, when the hydraulic pressure in the hydraulic chamber is released, a return spring in the hydraulic canceling chamber moves away the piston from the clutch plates, and thereby the clutch is disconnected. The supply of the hydraulic pressure to each hydraulic chamber or the release of the hydraulic pressure is controlled by switching ON/OFF of an electromagnetic valve provided to correspond to each hydraulic chamber. 
         [0006]    For this reason, for example, when a trouble such as disconnection or fixation occurs at at least one electromagnetic valve, there is a possibility that each clutch is held in a connected state and causes double engagement of a transmission. 
         [0007]    One of objects of the present invention is to provide a dual clutch apparatus capable of effectively preventing double engagement of a transmission. 
       Means for Solving the Problem 
     Solution to Problem 
       [0008]    To solve the problem, a dual clutch apparatus of a first aspect of the present invention is a dual clutch apparatus provided with a first clutch having a first, plate connecting and disconnecting power transmission from an engine to a first transmission input shaft, and a second clutch having a second plate connecting and disconnecting power transmission from the engine to a second transmission input shaft, and includes a first piston, a second piston, a first supply line, a second supply line, a first valve, a second valve, and valve control unit. The first piston presses the first plates to connect the first clutch by means of a hydraulic pressure supplied into a first hydraulic chamber, and moves away from the first plates to disconnect the first clutch by means of a first spring housed in a first hydraulic canceling chamber. The second piston presses the second plates to connect the second clutch by means of a hydraulic pressure supplied into a second hydraulic chamber, and moves away from the second plates to disconnect the second clutch by means of a second spring housed in a second hydraulic canceling chamber. The first supply line supplies the hydraulic pressure to the first hydraulic chamber and the second hydraulic canceling chamber. The second supply line supplies the hydraulic pressure to the second hydraulic chamber and the first hydraulic canceling chamber. The first valve is installed in the first supply line, and allows or blocks supply of the hydraulic pressure to the first hydraulic chamber and the second hydraulic canceling chamber. The second valve is installed in the second supply line, and allows or blocks supply of the hydraulic pressure to the second hydraulic chamber and the first hydraulic canceling chamber. The valve control unit controls opening/closing of the first valve and the second valve. When a clutch connected state in which one of the two valves is opened to connect one of the two clutches and the other valve is closed to disconnect the other clutch is changed to a two-clutch disconnected state in which the two valves are closed to disconnect the two clutches, the valve control unit closes the one valve and opens the other valve, and then closes the other valve before the other clutch is connected. 
         [0009]    In the above configuration, when the first valve is opened, the supply of the hydraulic pressure to the first hydraulic chamber and the second hydraulic canceling chamber is allowed, and thus the hydraulic pressure is supplied to the first hydraulic chamber and the second hydraulic canceling chamber via the first supply line. When the hydraulic pressure is supplied to the first hydraulic chamber, the first piston moves from the first hydraulic chamber side due to oil pressure, and presses the first plate to connect the first clutch. When the hydraulic pressure is supplied to the second hydraulic canceling chamber, the second piston moves away from the second plates due to the oil pressure from the second hydraulic canceling chamber side in addition to a biasing force of the second spring. For this reason, even when a trouble such as disconnection or fixation occurs at the second valve, the second piston can reliably move away from the second plates, and double -engagement of a transmission can be reliably prevented. When the second valve is opened, the hydraulic pressure is supplied to the first hydraulic canceling chamber. For this reason, the first piston reliably moves away from the first plates, the double engagement of the transmission can be reliably prevented. 
         [0010]    When the clutch connected state is changed to the two-clutch disconnected state, the valve control unit closes one of the two valves, and opens the other valve. For example, when, the second clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed to the two-clutch disconnected state, the valve control unit closes the second valve, and opens the first valve. Since the second valve is closed, the supply of the hydraulic pressure to the second hydraulic chamber is blocked, and the second piston moves away from the second plates due to the biasing force of the second spring. Since the first valve is opened, the supply of the hydraulic pressure to the second hydraulic canceling chamber is allowed, so that the hydraulic pressure is supplied to the second hydraulic canceling chamber, and the second piston moves away from the second plates due to the oil pressure from the second hydraulic canceling chamber side. That is, since the second piston moves away from the second plates due to the oil pressure from the second hydraulic canceling chamber side in addition to the biasing force of the second spring:, responsiveness of the second piston when the second clutch is disconnected can be improved. 
         [0011]    The valve control unit closes the one valve and opens the other valve, and then closes the other valve before the other clutch is connected. For example, when the valve control unit closes the second (or the one) valve and opens the first (or the other) valve, and then closes the first valve before the first clutch is connected. For this reason, since the hydraulic pressure supplied to the first hydraulic chamber is blocked before the first clutch is connected, the clutch connected state can be reliably changed to the two-clutch disconnected state. 
         [0012]    The valve control unit opens the other valve, and then closes the other valve before the other clutch is connected. For example, the valve control unit opens the first (or the other) valve, and then closes the first valve before the first clutch is connected. When the first valve is opened, the hydraulic pressure is supplied to the first hydraulic chamber, and thus the first piston moves in a direction pressing the first plates. When the first, valve is closed before the first clutch is connected, the first piston moving in the direction pressing the first plates moves in a direction moving away from the first plates due to a biasing force of the first spring, and the clutch connected state is changed to the two-clutch, disconnected state. For this reason, when the first clutch is connected at the two-clutch disconnected state, the first, piston may not completely move (not return) in the direction moving away from the first plates due to the biasing force of the first spring, in this ease, since the first piston has already moved in the direction pressing the first plates, responsiveness when the first clutch is connected is improved. 
         [0013]    Further, a dual clutch apparatus of a second aspect of the present invention is the dual clutch apparatus of the first aspect, and includes time counting unit for counting at least one of an elapsed time after the one valve is closed and an elapsed time after the other valve is opened. When the clutch connected state is changed to the two-clutch disconnected state, the valve control unit closes the one valve and opens the other valve, and then determines, based on the elapsed time counted by the time counting unit, whether or not it is before the other clutch is connected. 
         [0014]    In the above configuration,, the valve control unit closes the one valve and opens the other valve, and then determines, based on the elapsed time counted by the time counting unit, whether or not it is before the other clutch is connected. For example, when the clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed to the two-clutch disconnected state, a time (a first clutch connection time) until the first clutch is connected after the first valve is opened is previously obtained by an experiment or a simulation, and a time shorter than the obtained first clutch connection time is set as a given time. The valve control unit closes the second valve and opens the first valve, then determines to be before the first clutch is connected when the elapsed time counted by the time counting unit after the first valve is opened reaches the given time, and closes the first valve. 
         [0015]    When the other valve is opened in a state in which the one valve is closed, one piston moves away from the one plates due to the hydraulic pressure supplied to one hydraulic canceling chamber in addition to the biasing force of one spring, and the other piston begins to move toward the other plates against the biasing force of the other spring. That is, after one valve is closed and the other valve is opened, when the other valve is not closed, one clutch is disconnected, and then the other clutch is connected. For this reason, the valve control unit can close the other valve before the other clutch is connected by closing the other valve when the one clutch is disconnected. For example, when the second clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed to the two-clutch disconnected state, a time (a second clutch disconnection time) until the second clutch is disconnected after the second valve is closed is previously obtained by an experiment or a simulation, the obtained second clutch disconnection time is set as a given time. The valve control unit determines that the second clutch is disconnected (it is before the first clutch is connected) when the elapsed time counted by the time counting unit after the second valve is closed reaches the given time, and closes the first valve. 
         [0016]    When the other valve is closed until the other clutch is connected after the one clutch is disconnected, the other valve is opened until at least the one clutch is disconnected, and the hydraulic pressure is supplied to the one hydraulic canceling chamber. For this reason, responsiveness of the one piston when the one clutch is disconnected can be reliably improved. For example, when the second clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed to the two-clutch disconnected state, and the closing of the second valve and the opening of the first valve are performed nearly at the same time, the second clutch disconnection time and the first clutch connection time are previously obtained by an experiment or a simulation., and a time that is longer than the obtained second clutch disconnection time and is shorter than the obtained first clutch connection time is set as the given time. The valve control unit closes the first valve when the elapsed time counted by the time counting unit after the second valve is closed (the first valve is opened) reaches the given time. 
         [0017]    A dual clutch apparatus of a third aspect of the present invention is the dual clutch apparatus of the first aspect., and includes rotating speed detecting unit for detecting a rotating speed of one of the two transmission input shafts to which power from the engine is transmitted via the one clutch. When the clutch connected state is changed to the two-clutch disconnected state, the valve control unit closes the one valve and opens the other valve, then determines, based on the rotating speed detected by the rotating speed detecting unit, whether or not the one clutch is disconnected, and closes the other valve when it is determined that the one clutch is disconnected. 
         [0018]    in the above configuration, the valve control unit closes the one valve and opens the other valve, then determines, based on the rotating speed of the one transmission input shaft detected by the rotating speed detecting unit, whether or not the one clutch is disconnected, and closes the other valve when it is determined that the one clutch is disconnected. For example, when the second clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed to the two-clutch disconnected state, a reduction ratio of the rotating speed of the second transmission input shaft when the second clutch is changed from connection to disconnection is obtained by an experiment or a simulation, and is set as a given reduction ratio. When a reduction ratio per unit time of the rotating speed of the second transmission input shaft after the first valve is opened is greater than or equal to the given reduction ratio, it is determined that the second clutch is disconnected. As described above, when the first valve is opened in the state in which the second valve is closed, the second clutch is disconnected, and then the first clutch is connected. For this reason, the valve control unit determines that the second clutch is disconnected, and that it is before the first clutch is connected. 
         [0019]    A dual, clutch apparatus of a fourth aspect of the present invention is a dual clutch, apparatus provided with a first clutch having a first plate connecting and disconnecting power transmission from an engine to a first transmission input shaft, and a second clutch having a second plate connecting and disconnecting power transmission from the engine to a second transmission input shaft, and includes a first piston, a second piston, a first supply line, a second supply line, a first valve, a second valve, and valve control unit. The first piston presses the first plates to connect the first clutch by a hydraulic pressure supplied into a first hydraulic chamber, and moves away from the first plates to disconnect the first clutch by a first spring housed in a first hydraulic canceling chamber. The second piston, presses the second plates to connect the second clutch by a hydraulic pressure supplied into a second hydraulic chamber, and moves away from the second plates to disconnect the second clutch by a second spring housed in a second hydraulic canceling chamber. The first supply line supplies the hydraulic pressure to the first hydraulic chamber and the second hydraulic canceling chamber. The second supply line supplies the hydraulic pressure to the second hydraulic chamber and the first hydraulic canceling chamber. The first valve is installed in the first supply line, and makes it possible to adjust the hydraulic pressure supplied to the first hydraulic chamber and the second hydraulic canceling chamber. The second valve is installed in the second supply line, and makes it possible to adjust the hydraulic pressure supplied to the second hydraulic chamber and the first hydraulic canceling chamber. The valve control unit controls opening/closing of the first valve and the second valve. When a clutch connected state in which one of the two valves is opened to connect one of the two clutches and the other valve is closed to disconnect the other clutch is changed to a two-clutch disconnected state in which the two valves are closed to disconnect the two clutches, the valve control unit opens the other valve such that oil pressure smaller than a biasing force of the other spring disconnecting the other clutch acts on the other piston connecting and disconnecting the other clutch from the other hydraulic chamber side, and closes the one valve. 
         [0020]    In the above configuration, like the dual clutch apparatus of the first aspect, when the first valve is opened, the supply of the hydraulic pressure to the first hydraulic chamber and the second hydraulic canceling chamber is allowed. For this reason, for example, even when a trouble such as disconnection or fixation occurs at the second valve, the second piston, can reliably move away from the second plates,, and the double engagement of the transmission can be reliably prevented. When the second valve is opened, the hydraulic pressure is supplied to the first hydraulic canceling chamber. For this reason, the first piston can reliably move away from the first plates, and the double engagement of the transmission can be reliably prevented. 
         [0021]    The valve control unit opens the other valve such that the oil pressure smaller than the biasing force of the other spring acts on the other piston from the other hydraulic chamber side. When the second clutch connected state in which the first (or the other) clutch is disconnected and the second (or the one) clutch is connected is changed, to the two-clutch disconnected state, the second valve is opened such that the oil pressure smaller than the biasing force of the second spring acts on the second piston from the second hydraulic chamber side, for example. For this reason, even when the second valve is opened, the second piston does not move in a direction pressing the second plates due to the oil pressure from the second hydraulic chamber side, and the second clutch is not connected. That is, the valve control unit can improve the responsiveness of the first piston when supplying the hydraulic pressure to the first hydraulic, canceling chamber to disconnect the first clutch without opening the second valve to connect the second clutch. 
       Advantageous Effect of the Invention 
       [0022]    According to the dual clutch apparatus of the present invention, double engagement of a transmission can be effectively prevented. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0023]      FIG. 1  is a gear layout view of a dual, clutch type transmission connected to a dual clutch apparatus according to a first embodiment of the present invention. 
           [0024]      FIG. 2  is a view illustrating an operated state corresponding to a shift position of the dual clutch type transmission of  FIG. 1 . 
           [0025]      FIG. 3  is a schematic longitudinal sectional view illustrating an upper half of the dual clutch apparatus according to the first embodiment. 
           [0026]      FIG. 4  is a view illustrating a state in which, a first, wet clutch, is connected and a second wet clutch is disconnected in the dual clutch apparatus according to the first embodiment. 
           [0027]      FIG. 5  is a view illustrating a state in which the first wet clutch is disconnected and the second wet clutch is connected in the dual clutch apparatus according to the first embodiment. 
           [0028]      FIG. 6  is a view illustrating hydraulic pressure acting on each piston, and a biasing force of each return spring in the dual clutch apparatus according to the first embodiment. 
           [0029]      FIG. 7  is a schematic longitudinal sectional view illustrating an upper half of a dual clutch apparatus according to a second embodiment. 
           [0030]      FIG. 8  is a schematic longitudinal sectional view illustrating an upper half of a dual clutch apparatus according to a third embodiment 
           [0031]      FIG. 9  is a view illustrating hydraulic pressure acting on a first piston and a biasing, force of a first return spring in the dual clutch apparatus according to the third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0032]    Hereinafter, a first embodiment of the present invention will be described on the basis of the drawings. 
         [0033]    As illustrated in  FIG. 1 , a dual clutch apparatus to according to the present embodiment is connected to a dual clutch type transmission  1 , and transmits a rotating force from an engine E to the dual clutch type transmission  1 . The dual clutch apparatus  10  is provided with a first wet clutch C 1  and a second wet clutch C 2 . Note that a reference sign  11  indicates a clutch input shaft to which power of the engine E is transmitted. 
         [0034]    The dual clutch type transmission  1  has a first transmission input shaft  12 A, a second transmission input shaft  12 B, an output shaft  2 , and a counter shaft  3 . The first transmission input shaft  12 A is an outer shaft formed in a tube shape, and is used, for example, in odd numbered stages of the dual clutch type transmission  1  (see  FIG. 2 ). The second transmission input shaft  12 B is an inner shaft that is rotatably and pivotally supported in a hollow shaft of the first transmission input shaft  12 A via a bearing  13 , and is used, for example, in even numbered stages of the dual clutch type transmission  1  (see  FIG. 2 ). The output shaft  2  is arranged coaxially with axes of rotation of the first transmission input shaft  12 A and the second transmission input shaft  12 B. The counter shaft  3  is arranged to he parallel with axes of rotation of the first transmission input shaft  12 A, the second transmission input shaft  12 B, and the output shaft  2 . Each of the shafts  12 A,  12 B,  2 , and  3  is provided with a plurality of gears, and a plurality of gear trains  4  to  9  are constituted by the gears. 
         [0035]    The plurality of gear trains  4  to  9  are arranged from the engine E in the order of a first reduction gear train  4 , a second reduction gear train  5 , a third and fourth gears&#39; gear train  6 , a first and second gears&#39; gear train  7 , a reverse gear train  8 , and a seventh and eighth gears&#39; gear train  9  in turns. The first reduction gear train  4  is constituted by a first input gear  4   a  of the first transmission input shaft  12 A and a first intermediate gear  4   b  of the counter shaft  3 . The second reduction gear train  5  is constituted by a second input gear  5   a  of the second transmission input shaft  128  and a second intermediate gear  5   b . The third and fourth gears&#39; gear train.  6  is constituted by a first output gear  6   a  of the output shaft  2  and a third intermediate gear  6   b  of the counter shaft  3 . The first and second gears&#39; gear train  7  is constituted, by a second output gear  7   a  of the output shaft  2  and a fourth intermediate gear  7   b  of the counter shaft  3 . The reverse gear train  8  is constituted by a third output gear  8   a  of the output shaft  2 , a fifth intermediate gear  8   b  of the counter shaft  3  and an idler gear  8   c . The seventh, and: eighth gears&#39; gear train  9  is constituted, by a fourth output gear  9   a  of the output shaft  2  and a sixth intermediate gear  9   b  of the counter shaft  3 . 
         [0036]    The first output gear  6   a , the second output gear  7   a , and the third output gear  8   a  of the output shaft  2  are provided to be rotatable relative to the output shaft  2 , and the fourth output gear  9   a  is fixedly provided for the output shaft  2 . The first output gear  6   a  can be connected to and disconnected from the output shaft  2  by movement of a first sleeve  70 , and the second output gear  7   a  and the third output gear  8   a  can be connected to and disconnected from the output shaft  2  by movement of a second sleeve  71 . The first intermediate gear  4   b , the second intermediate gear  5   b , the third intermediate gear  6   b , the fourth intermediate gear  7   b , and the fifth intermediate gear  8   b  of the counter shaft  3  is fixedly provided for the counter shaft  3 , and the sixth intermediate gear  9   b  is provided to be rotatable relative to the counter shaft  3 . The sixth intermediate gear  9   b  can be connected to and disconnected from the counter shaft  3  by movement of a third sleeve  72 . 
         [0037]    As illustrated in  FIG. 2 , in a state in which the output shaft  2  and the second output gear  7   a  are connected by the movement of the second sleeve  71 , when the power of the engine E is transmitted from the clutch input shaft  11  to the first transmission input shaft  12 A, the dual clutch type transmission  1  becomes a first gear, and when transmitted to the second transmission input shaft  128 , the dual clutch type transmission  1  becomes a second gear. In a stale in which the output shaft  2  and the first output gear  6   a  are connected, by the movement of the first sleeve  70 , when the power of the engine E is transmitted from the clutch input shaft  11  to the first transmission input shaft  12 A, the dual clutch type transmission i becomes a third gear, and when transmitted to the second transmission input shaft  12 B, the dual clutch type transmission  1  becomes a fourth gear. In a state in which the second transmission input shaft  12 B and the output shaft  2  are connected by the movement of the first sleeve  70 , when the power of the engine E is transmitted from the clutch input shaft  11  to the first transmission input shaft  12 A, the dual clutch type transmission  1  becomes a fifth gear, and when transmitted to the second transmission, input shaft  12 B, the dual clutch type transmission  1  becomes a sixth gear. In a state in which the counter shaft  3  and the sixth intermediate gear  9   b  are connected by the movement of the third sleeve  72 , when the power of the engine E is transmitted from the clutch input shaft  11  to the first transmission input shaft  12 A, the dual clutch type transmission  1  becomes a seventh gear, and when transmitted to the second transmission input shaft  12 B, the dual clutch type transmission  1  becomes an eighth gear. 
         [0038]    As illustrated  FIG. 3 , the dual clutch apparatus  10  is provided with a first wet clutch C 1 , a first piston  23 , a second wet clutch C 2 , a second piston  33 , a hydraulic pressure circuit  40 , a first electromagnetic valve (a first valve)  60 , a second electromagnetic valve (a second valve)  65 , and an electronic control unit (valve control unit or time counting unit)  80  (hereinafter, referred to as an electric control unit (ECU)). 
         [0039]    The first wet clutch C 1  is provided with a clutch hub  20  that is rotated integrally with the clutch input shaft  11 , a plurality of first inner plates  21 A that are spline-fitted with the clutch hub  20 , a first clutch drum  22  that is rotated integrally with the first transmission input shaft  12 A, and a plurality of first outer plates  21 B that are alternately arranged between the first inner plates  21 A and are spline-fitted with the first clutch drum  22 . 
         [0040]    The first piston  23  is formed in a cylindrical shape, can press each of the first plates  21 A and  21 B in an axial direction, and is slidably housed in an annular first piston, chamber  24  formed in the clutch hub  20 . A first hydraulic chamber  25 A and a first centrifugal hydraulic canceling chamber (a first hydraulic canceling chamber)  25 B are defined in the first piston chamber  24  by the first piston  23 . A first return spring (a first spring)  26  biasing the first, piston  23  in a direction in which the first piston  23  moves away from, each of the first plates  21 A and  21 B is housed in the first centrifugal hydraulic canceling chamber  25 B. A reference sign S indicates a seal member that seals a gap between the first piston  23  and the first piston chamber  24 . 
         [0041]    When hydraulic pressure is supplied to the first hydraulic chamber  25 A, the first piston  23  stroke-moves in an axial direction to connect the first plates  21 A and  21 B under pressure (the first wet clutch C 1 ; connection). On the other hand, when the hydraulic pressure of the first hydraulic chamber  25 A is dropped and hydraulic pressure is supplied to the first centrifugal hydraulic canceling chamber  25 B, the first piston  23  moves away from each of the first plates  21 A and  21 B due to a biasing force of the first return spring  26  and oil pressure inside the first centrifugal hydraulic canceling chamber  25 B, and releases the pressure-connected state (the first wet clutch C 1 : disconnection). In this specification, the hydraulic pressure refers to a force that is applied per unit area of a target by pressure oil. In addition, the oil pressure refers to a force that is applied to a target by pressure oil, and: a value obtained by multiplying, hydraulic pressure and an area. 
         [0042]    The second wet clutch C 2  is provided with a plurality of second outer plates  31 A that are spline-fitted with the clutch hub  20 , a second clutch drum  32  that is rotated integrally with the second transmission input shaft  12 B, and a plurality of second inner plates  31 B that are alternately arranged between the second outer plates  31 A and are spline-fitted, with the second clutch drum  32 . 
         [0043]    The second piston  33  is formed in a cylindrical shape, can connect the second plates  31 A and  31 B under pressure in an axial direction, and is slidably housed in an annular second piston chamber  34  formed in the clutch hub  20 . A second hydraulic chamber  35 A and a second centrifugal hydraulic canceling chamber (a second hydraulic canceling chamber)  35 B are defined in the second piston chamber  34  by the second piston  33 . A second return spring (a second spring)  36  biasing the second piston  33  in a direction in which the second piston  33  moves away from each of the second plates  31 A and  31 B is housed in the second centrifugal hydraulic canceling chamber  35 B. A reference sign S indicates a seal member that seals a gap between the second piston  33  and the second piston chamber  34 , 
         [0044]    When hydraulic pressure is supplied to the second hydraulic chamber  35 A, the second piston  33  stroke-moves in an axial, direction to connect the second plates  31 A and  31 B under pressure (the second wet clutch C 2 : connection). On the other hand, when the hydraulic pressure of the second hydraulic chamber  35 A is dropped and hydraulic pressure is supplied to the second centrifugal hydraulic canceling chamber  35 B, the second piston  33  moves away from each of the second plates  31 A and  31 B due to a biasing force of the second return spring  36  and oil pressure inside the second, centrifugal hydraulic canceling chamber  35 B, and releases the pressure-connected state (the second wet clutch C 2 ; disconnection). 
         [0045]    The hydraulic pressure circuit  40  has a first upstream supply line (a first supply line)  43  that connects an oil pan  41  and a first electromagnetic valve  60 , and a second upstream supply line (a second supply line)  45  that branches off from the first upstream supply line  43  and is connected to the second electromagnetic valve  65 . An oil pump OP driven by the power of the engine E is installed on the first upstream supply line  43  upstream from the branch part. A lubricating oil supply line  46  on which a throttle valve  47  is installed is connected to the second upstream supply line  45 . 
         [0046]    A first downstream supply line (a first supply line)  50  is connected to the first electromagnetic valve  60 . The first downstream supply line  50  branches off into a first hydraulic chamber-purpose line  50 A and a second canceling chamber-purpose line  50 B in the clutch hub  20 . A downstream end of the first hydraulic chamber-purpose line  50 A is connected to the first hydraulic chamber  25 A, and a downstream end of the second canceling chamber-purpose line  50 B is connected to the second centrifugal hydraulic canceling chamber  35 B. 
         [0047]    The first electromagnetic valve  60  is closed by a biasing force of a spring  61  during non-current application (OFF), and is opened when current application (ON) is performed by the ECU  80 . When the first electromagnetic valve  60  is opened (ON), pressure oil is supplied to the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B. On the other hand, when the first electromagnetic valve  60  is closed (OFF), no pressure oil is supplied to the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B, and the pressure oil inside the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B returns to the oil pan  41  via an oil return line  62 . 
         [0048]    A second downstream supply line (a second supply line)  51  is connected to the second electromagnetic valve  65 . The second downstream supply line  51  branches off into a second hydraulic chamber-purpose line  51 A and a first canceling chamber-purpose line  51 B in the clutch hub  20 . A downstream end of the second hydraulic chamber-purpose line  51 A is connected to the second hydraulic chamber  35 A, and a downstream end of the first canceling chamber-purpose line  51 B is connected to the first centrifugal hydraulic canceling chamber  25 B. 
         [0049]    The second electromagnetic valve  65  is closed, by a biasing force of a spring  66  during non-current application (OFF), and is opened when current application (ON) is performed by the ECU  80 . When the second electromagnetic valve  65  is opened (ON), pressure oil is supplied, to the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B. On the other hand, when the second electromagnetic valve  65  is closed (OFF), no pressure oil is supplied to the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B, and the pressure oil inside the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B returns to the oil pan  41  via an oil return line  67 . 
         [0050]    The ECU  80  is made up of a central processing unit (CPU), a memory (not shown), and the like, has a valve control part  81  and a time counting part  82 , and functions as valve control unit and time counting unit. 
         [0051]    The tune counting part  82  counts an elapsed time after the first electromagnetic valve  60  is turned ON when a clutch connected state is changed to a two-clutch disconnected state (to be described below). As will be described below, since ON of the first electromagnetic valve  60  and OFF of the second electromagnetic valve  65  are performed approximately at the same time., the time counting part  82  may count an elapsed time after the second electromagnetic valve  65  is turned OFF. 
         [0052]    The valve control part  81  controls opening/closing of the first electromagnetic valve  60  and the second electromagnetic valve  65 , and thereby switching a first clutch connected state (see  FIG. 4 ) in which the first wet clutch C 1  is connected and the second wet clutch C 2  is disconnected, a second clutch connected state (see  FIG. 5 ) in which the first wet clutch C 1  is disconnected and the second wet clutch C 2  is connected, and the two-clutch disconnected state (see  FIG. 3 ) in which the first wet clutch C 1  and the second wet clutch C 2  are disconnected. 
         [0053]    As illustrated in  FIG. 2 , in the dual clutch type transmission  1 , in the event of odd numbered stages (first gear, third gear, fifth gear, and seventh gear), the power of the engine E is transmitted from the clinch input shaft  11  to the first transmission input shaft  12 A. For this reason, as illustrated in  FIG. 4  the valve control part  81  turns ON the first electromagnetic valve  60  and turns OFF the second electromagnetic valve  65  to be made into the first clutch connected state. For example, when the dual clutch type transmission  1  is set to the first gear, the valve control part  81  turns ON the first electromagnetic valve  60  and turns OFF the second electromagnetic valve  65  to be made info the first clutch connected state in a state in which the output shaft  2  and the second output gear  7   a  are connected by the movement of the second sleeve  71 . Thereby, the power of the engine E is input from the clutch input shaft  11  to the first transmission input shaft  12 A, and is transmitted to the output shaft  2  via the first reduction gear train  4 , the counter shaft  3 , and the first and second gears&#39; gear train  7 . 
         [0054]    As illustrated in  FIG. 2 , in the dual clutch type transmission  1 , in the event of even numbered stages (second gear, fourth gear, sixth gear, and eighth gear), the power of the engine E is transmitted from the clutch input shaft  11  to the second transmission input shaft  12 B. For this reason, as illustrated in  FIG. 5 , the valve control part  81  turns OFF the first electromagnetic valve  60  and turns ON the second electromagnetic valve  65  to be made into the second clutch connected state. For example, on shifting up from the first gear to the second gear, the valve control part  81  turns OFF the first electromagnetic valve  60  and turns ON the second electromagnetic valve  65  to be changed from the first clutch connected state into the second clutch connected state in a state in which the output shaft  2  and the second output gear  7   a  are still connected by the second sleeve  71  without moving each of the sleeves  70  to  72 . Thereby, the power of the engine E is input from the clutch input shaft  11  to the second transmission input shaft  12 B, and is transmitted to the output shaft  2  via the second reduction gear train  5 , the counter shaft  3 , and the first and second gears&#39; gear train  7 . 
         [0055]    As illustrated to  FIG. 2 , in the dual clutch type transmission  1 , on shifting up from the even numbered stage to the odd numbered stage (from the second gear to the third gear, from the fourth gear to the fifth gear, or from the sixth gear to the seventh gear), movement of any one of the sleeves  70  to  72  occurs. For this reason, a change from the second clutch connected state (the clutch connected state) in which the second wet clutch C 2  is connected by turning OFF the first (or the other) electromagnetic valve  60  and turning ON the second (or the one) electromagnetic valve  65  to the two-clutch, disconnected state in which the second wet clutch C 2  is disconnected is performed. After the sleeve is moved, a change from the two-clutch disconnected state to the first clutch connected state in which the first, wet clutch C 1  is connected is performed. When the second clutch connected state is changed into the two-clutch disconnected state, the valve control part  81  turns OFF the second electromagnetic valve  65  and nearly simultaneously turns ON the first electromagnetic valve  60 , and determines that it is before the first wet clutch C 1  is connected when an elapsed time which the time counting part  82  counts (an elapsed time after the first electromagnetic valve  60  is turned ON) reaches a given elapsed time set previously, and then turns OFF the first electromagnetic valve  60 . A time (a second clutch disconnection time) until the second wet clutch C 2  is disconnected after the second electromagnetic valve  65  is turned OFF, and a time (a first clutch connection lime) until the first wet clutch C 1  is connected after the first electromagnetic valve  60  is turned ON are previously obtained by an experiment or a simulation, and a time that is longer than the obtained second clutch disconnection time and is shorter than the obtained first clutch connection time is set as the given elapsed time. 
         [0056]    Next, setting of an optimal biasing force of each of the return springs  26  and  36  will be described on the basis of  FIG. 6 . In  FIG. 6 , RA 1  indicates an outer diameter of the first piston  23 , RB 1  indicates an outer diameter of the first centrifugal hydraulic canceling chamber  25 B, RA 2  indicates an outer diameter of the second piston  33 , RB 2  indicates an outer diameter of the second centrifugal hydraulic canceling chamber  35 B, P indicates a hydraulic pressure, FS 1  indicates a biasing force of the first return spring  26 , FS 2  indicates a biasing force of the second return spring  36 , CL indicates an axis of rotation of the clutch input shaft  11 . The outer diameters represent radii from the axis CL of rotation. 
         [0057]    The biasing force FS 1  of the first return spring  26  is set to meet Conditional Expression (1) below, and the biasing force FS 2  of the second return spring  36  is set to meet Conditional Expression (2) below. 
         [0000]      [Expression 1] 
         [0000]      ( R   A1   2   −R   B1   2 )·π· P&lt;F   S1    (1)
 
         [0000]      [Expression 2] 
         [0000]      ( R   A2   2   −R   B2   2 )·π· P&lt;F   S2    (2)
 
         [0058]    In the dual clutch apparatus  10  configured as described above, when the power is transmitted from: the clutch input shaft  11  to the first transmission input shaft  12 A, as illustrated in  FIG. 4 , the first wet clutch C 1  is connected (the first electromagnetic valve  60 ; ON), and the second wet clutch C 2  is disconnected (the second electromagnetic valve  65 : OFF). When, the first electromagnetic valve  60  is turned ON, the hydraulic pressure is supplied to not only the first hydraulic chamber  25 A but also the second centrifugal hydraulic canceling chamber  35 B. For this reason, both the biasing force FS 2  of the second return spring  36  and the oil pressure inside the second centrifugal hydraulic canceling chamber  35 B act on the second piston  33 . As a result, for example, even when a trouble such as disconnection or fixation occurs at the second electromagnetic valve  65 , the second piston  33  can reliably move away from each of the plates  31 A and  31 B, and double engagement of the transmission can be reliably prevented. 
         [0059]    When the power is transmitted from the clutch, input shaft  11  to the second transmission input shaft  12 B, as illustrated in  FIG. 5 , the first wet-clutch C 1  is disconnected (the first electromagnetic valve  60 : OFF), and the second wet clutch C 2  is connected (the second electromagnetic valve  65 : ON). When the second electromagnetic valve  65  is turned ON, the hydraulic pressure is supplied to not only the second hydraulic chamber  35 A but also the first centrifugal hydraulic canceling chamber  25 B. For this reason, both the biasing force FS 1  of the first return spring  26  and the oil pressure inside the first centrifugal hydraulic canceling chamber  25 B act on the first piston  23 . As a result, for example, even when a trouble such as disconnection or fixation occurs at the first electromagnetic valve  60 , the first piston  23  can reliably move away from each of the plates  21 A and  21 B, and the double engagement of the transmission can be reliably prevented. 
         [0060]    Since the biasing force FS 1  of the first return spring  26  is set to be greater than, a difference between the oil pressures of the first hydraulic chamber  25 A and the first centrifugal hydraulic canceling, chamber  25 B which act on the first piston  23 , and the biasing force FS 2  of the second return spring  36  is set to be greater than a difference between the oil pressures of the second hydraulic chamber  35 A and the second centrifugal hydraulic canceling chamber  35 B which act on the second piston  33 , the first and second wet clutches C 1  and C 2  are reliably disconnected, and the double engagement of the transmission can be effectively prevented. 
         [0061]    When the second clutch connected state is changed into the two-clutch disconnected state, the valve control part  81  turns OFF the second electromagnetic valve  65 , and nearly simultaneously turns ON the first electromagnetic valve  60 . Since the second electromagnetic valve  65  is turned OFF, the supply of the hydraulic pressure to the second hydraulic chamber  35 A is blocked, and the second piston  33  moves away from each of the second plates  31 A and  31 B due to the biasing force FS 2  of the second return spring  36 . Since the first electromagnetic valve  60  is opened, the supply of the hydraulic pressure to the second centrifugal hydraulic canceling chamber  35 B is allowed. The hydraulic pressure is supplied to the second centrifugal hydraulic canceling chamber  35 B, and the second piston  33  moves away from each of the second plates  31 A and  31 B due to the oil pressure from the second centrifugal hydraulic canceling chamber  35 B side. That is, since the second piston  33  moves away from each of the second plates  31 A and  31 B due to the oil pressure from the second centrifugal hydraulic canceling chamber  35 B side in addition to the biasing force FS 2  of the second return spring  36 , responsiveness of the second piston  33  when the second wet clutch C 2  is disconnected can be improved. 
         [0062]    When the second clutch connected state is changed into the two-clutch disconnected state, the valve control part  81  turns OFF the second electromagnetic valve  65  and nearly simultaneously turns ON the first electromagnetic valve  60 , and then turns OFF the first electromagnetic valve  60  before the first wet clutch C 1  is connected. When the valve control part  81  turns ON the first electromagnetic valve  60 , the hydraulic pressure is supplied to the first hydraulic chamber  25 A, and thus the first piston  23  moves in a direction in which it presses each of the first plates  21  A and  21 B. Afterwards, when the first electromagnetic valve  60  is turned OFF before the first wet clutch C 1  is connected, the hydraulic pressure to be supplied to the first hydraulic chamber  25 A is blocked, and thus the first piston  23  that has moved, in the direction pressing each of the first plates  21 A and  21 B is moved in a direction in which it moves away from each of the first plates  21 A and  21 B due to the biasing force FSi of the first return spring  26 , and the second clutch connected state becomes the two-clutch disconnected state. In this way, as the first electromagnetic valve  60  is turned OFF before the first wet clutch C 1  is connected, the second clutch connected state can be reliably changed to the two-clutch disconnected state. 
         [0063]    When the second clutch connected state is changed to the two-clutch disconnected state, the valve control, part  81  turns OFF the second electromagnetic valve  65  and nearly simultaneously turns ON the first electromagnetic valve  60 . When the elapsed time which the time counting part  82  counts reaches the given elapsed time, the valve control, part  81  turns OFF the first electromagnetic valve  60 . A time that is longer than the second clutch disconnection time and is shorter than the first clutch connection time is set as the given elapsed time. That is, the valve control part  81  turns OFF the first electromagnetic valve  60  after the second wet clutch C 2  is disconnected and before the first wet clutch C 1  is connected. In this way, the first electromagnetic valve  60  is opened until at least the second wet clutch C 2  is disconnected, and the hydraulic pressure is supplied to the second centrifugal hydraulic canceling chamber  35 B. For this reason, the responsiveness of the second piston  33  when the second wet clutch C 2  is disconnected can be reliably improved. 
         [0064]    On shifting up, for example, from the second gear to the third gear, a change from the second clutch connected state of the second gear to the two-clutch disconnected slate for the movement of the sleeves  70  and  71  is performed, and a change from the two-clutch disconnected state to the first clutch connected state after the movement of the sleeves  70  and  71  is performed. When the change from the two-clutch disconnected state to the first clutch connected state is performed, the first piston  23 , which has moved in the direction pressing each of the first plates  21 A and  21 B in the event of the change from the second clutch connected state to the two-clutch disconnected, state, may not completely move (not return) in the direction moving away from each of the first plates  21 A and  21 B due to the biasing force FS 1  of the first return spring  26 . In this case, since the first piston  23  has already moved in the direction pressing each of the first plates  21 A and  21 B, responsiveness when the first wet clutch C 1  is connected is improved. 
         [0065]    in the present embodiment, the time that is longer than the second clutch disconnection time and is shorter than the first clutch connection, time is set as the given elapsed time, but the invention, is not limited thereto. The set time may be a time shorter than the first clutch connection time. For example, the second clutch disconnection time may be set as the given elapsed time, the valve control part  81  may determine that the second wet clutch C 2  is disconnected (before the first wet clutch C 1  is connected) when the elapsed time which the time counting part  82  counts (the elapsed time after the first electromagnetic valve  60  is turned ON) reaches the second clutch disconnection time, and turn OFF the first electromagnetic valve  60 . Alternatively, a time shorter than the second clutch disconnection time may be set as the given elapsed time. 
         [0066]    In the present embodiment, the change from the second clutch connected state to the two-clutch disconnected state which is performed on shifting up from the even numbered, stage to the odd numbered stage (from the second gear to the third gear, from the fourth gear to the fifth gear, or from the sixth gear to the seventh gear) has been described. However, the invention may be also applied to the case of a change from the first clutch connected state to the two-clutch disconnected state which is performed on shifting down from the odd numbered stage to the even numbered stage. In this case, the first (or the one) electromagnetic valve  60  is turned OFF, and nearly simultaneously the second (or the other) electromagnetic valve  65  is turned ON. Then, before the second wet clutch C 2  is connected, the second electromagnetic valve  65  is turned OFF. 
         [0067]    in the present embodiment, when the second clutch connected state is changed to the two-clutch disconnected state, the valve control part  81  turns OFF the second electromagnetic valve  65  and nearly simultaneously turns ON the first electromagnetic valve  60 . However, OFF of the second electromagnetic valve  65  and ON of the first electromagnetic valve  60  may not be performed nearly at the same time. Even when OFF of the second electromagnetic valve  65  and ON of the first electromagnetic valve  60  are performed with different timings, if a time for which the first electromagnetic valve  60  is turned ON after the second electromagnetic valve  65  is turned OFF (or the second electromagnetic valve  65  is turned OFF after the first electromagnetic valve  60  is turned ON) is constant, the time counting part  82  may count any one of an elapsed time after the first electromagnetic valve  60  is turned ON and an elapsed time after the second electromagnetic valve  65  is turned OFF. 
         [0068]    In the present embodiment, the ECU  80  has the valve control part  81  and the time counting part  82 , and functions as the valve control unit and the time counting unit, but the invention is not limited thereto. For example, the ECU  80  may have the valve control part  81  to function as the valve control unit, and acquire an elapsed time which the time counting part (the time counting unit) provided separately from the ECU  80  counts 
         [0069]    Next, a second embodiment of the present invention will be described on the basis of the drawings. A dual clutch apparatus  90  according to the present embodiment is different from that of the first embodiment in that it is determined on the basis of a rotating speed of a second transmission input shaft  12 B whether it is before a first wet clutch C 1  is connected when a clutch connected state is changed to a two-clutch disconnected state. The same components as the first embodiment are given the same reference signs, and description thereof will be omitted. 
         [0070]    As illustrated in  FIG. 7 , the dual clinch apparatus  90  is provided with a rotating speed sensor (rotating speed detecting unit)  91  that detects the rotating speed of the second transmission input shaft  12 B. 
         [0071]    The rotating speed sensor  91  detects the rotating speed of the second transmission input shaft  12 B, and sequentially outputs it to an ECU  80 . 
         [0072]    When a second clutch connected state (see  FIG. 5 ) is changed to a two-clutch disconnected state (see  FIG. 7 ), a valve control part  81  of the ECU  80  turns OFF a second electromagnetic valve  65  and nearly simultaneously turns ON a first electromagnetic valve  60 . Then, the valve control part  81  obtains a reduction ratio per unit time of the rotating speed of the second transmission input shaft  12 B from the rotating speed of the second transmission input shaft  12 B which is detected, by the rotating speed sensor  91 , and determines that a second wet clutch C 2  is disconnected when the obtained reduction ratio is greater than or equal to a given reduction ratio set previously. That is, as the valve control part  81  determines that the second wet clutch C 2  is disconnected, the valve control part  81  determines that it is before the first wet clutch C 1  is connected, and turns OFF the first electromagnetic valve  60 . The reduction ratio of the rotating speed of the second transmission input shaft  12 B when the second wet clutch C 2  is changed from connection to disconnection is previously obtained by an experiment or a simulation, and the obtained reduction ratio is set as the given reduction ratio. 
         [0073]    In the above-configuration, the valve control part  81  can determine whether or not it is before the first wet clutch C 1  is connected by determining whether or not, based on the rotating speed of the second transmission input shaft  128 , the second wet clutch C 2  is disconnected. 
         [0074]    In the present embodiment, whether or not the second wet clutch C 2  is disconnected is determined by a comparison of the reduction ratio per unit time of the rotating speed of the second transmission input shaft  12 B and the given reduction ration set previously, but the invention is not limited thereto. For example, whether or not the second wet clutch C 2  is disconnected may be determined using a difference in the rotating speed per unit time of the second transmission input shaft  12 B or the like. 
         [0075]    Next,, a third embodiment of the present invention will be described on the basis of the drawings. A dual clutch apparatus  100  according to the present embodiment is provided with a first hydraulic pressure regulation valve  101  and a second hydraulic pressure regulation valve  102  in place of the first electromagnetic valve  60  and the second electromagnetic valve  65  of the first embodiment. The same components as the first embodiment are given the same reference signs, and description thereof will be omitted. 
         [0076]    As illustrated in  FIG. 8 , the dual clutch apparatus  100  is provided with a first hydraulic pressure regulation valve (a first valve)  101  that is connected to a first upstream supply line  43  and a first downstream supply line  50 , a first hydraulic pressure sensor  103  that is provided for the first downstream supply line  50 , a second hydraulic pressure regulation valve (a second valve)  102  that is connected to a second upstream supply line  45  and a second downstream supply line  51 , and a second hydraulic pressure sensor  104  that is provided for the second downstream supply line  51 . 
         [0077]    The first hydraulic pressure regulation valve  101  can adjust a hydraulic pressure that is supplied to a first hydraulic chamber  25 A and a second centrifugal hydraulic canceling chamber  35 B via the first downstream supply line  50 . When the first hydraulic pressure regulation valve  101  is opened (ON), pressure oil is supplied to the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B. On the other hand, when the first hydraulic pressure regulation valve  101  is closed (OFF), no pressure oil is supplied to the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B, and the pressure oil inside the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 S returns to an oil pan  41  via an oil return line  62 . 
         [0078]    The second hydraulic pressure regulation valve  102  can adjust a hydraulic pressure that is supplied to a second hydraulic chamber  35 A and a first centrifugal hydraulic canceling chamber  25 B via the second downstream supply line  51 . When the second hydraulic pressure regulation valve  102  is opened (ON), pressure oil is supplied to the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B. On the other hand, when the second hydraulic pressure regulation valve  102  is closed (OFF), no pressure oil is supplied to the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B, and the pressure oil inside the second hydraulic chamber  35 A and the first centrifugal hydraulic canceling chamber  25 B returns to the oil pan  41  via an oil return line  67 . 
         [0079]    The first hydraulic pressure sensor  103  detects the hydraulic pressure of the first downstream supply line  50 , and sequentially outputs it to an ECU  80 . The second hydraulic pressure sensor  104  detects the hydraulic pressure of the second downstream supply line  51 , and sequentially outputs it to the ECU  80 , 
         [0080]    When a change from a second clutch connected state (a clutch connected state, see  FIG. 8 ). In which a second wet clutch C 2  is connected by turning OFF the first (or the other) hydraulic pressure regulation valve  101  and turning ON the second (or the one) hydraulic pressure regulation valve  102 , to a two-clutch disconnected state (see  FIG. 9 ), in which the second wet clutch C 2  is disconnected, is performed, a valve control part  81  of the ECU  80  turns OFF the second hydraulic pressure regulation valve  102  and nearly simultaneously turns ON the first hydraulic pressure regulation valve  101 . When the valve control part  81  turns ON the first hydraulic pressure regulation valve  101 , the valve control part  81  controls the first hydraulic pressure regulation valve  101  such, that the hydraulic pressure of the first downstream supply line  50  which is detected by the first hydraulic pressure sensor  103  becomes a given hydraulic pressure. 
         [0081]    A value obtained when oil pressure acting on a first piston  23  from the first hydraulic chamber  25 A side when the first hydraulic pressure regulation, valve  101  is opened is made smaller than a biasing force of a first return spring  26  is set as the given hydraulic pressure. Fox example, in the dual clutch apparatus  100  of  FIG. 9 , the given hydraulic pressure is set to meet Conditional Expression (3) below. In  FIG. 9 , RA 1  indicates an outer diameter of the first piston  23 , RC 1  indicates an inner diameter of the first piston  23 , P 1  indicates the hydraulic pressure, and FS 1  indicates the biasing force of the first return spring  26 . Both the outer diameter and the inner diameter represent radii from an axis CL of rotation. 
         [0000]      [Expression 3] 
         [0000]        F   S1 /(( R   A1   2   −R   C1   2 )·π)&gt; P   1    (3)
 
         [0082]    A conditional expression for obtaining the given hydraulic pressure is not limited to Conditional Expression (3) above. For example, when a shape of the first piston is another shape, the conditional expression maybe another conditional expression, 
         [0083]    In the dual clutch apparatus  100  configured as described above, when the second clutch connected state (see  FIG. 8 ) is changed to the two-clutch disconnected state (see  FIG. 9 ), the second hydraulic pressure regulation valve  102  is turned OFF, and nearly simultaneously the first hydraulic pressure regulation valve  101  is turned ON. Since the hydraulic pressure supplied, to the first hydraulic chamber  25 A (and the second centrifugal hydraulic canceling chamber  35 B) by turning ON the first hydraulic pressure regulation valve  101  is the given hydraulic pressure set previously, the oil pressure acting on the first piston  23  is smaller than the biasing force of the first return spring  26 . For this reason, even when the first hydraulic pressure regulation valve  101  is turned ON, the first piston  23  does not move in a direction in which the first wet clutch C 1  is connected. Since the hydraulic pressure is supplied to the second centrifugal hydraulic canceling chamber  35 B by aiming ON the first hydraulic pressure regulation valve  101 , a second piston  33  moves away from each of second plates  31 A and  31 B due to the oil pressure acting from the second centrifugal hydraulic canceling chamber  35 B side in addition to the biasing force of the second return spring  36 , releases the pressure-connected state, and the second wet; clutch C 2  is disconnected. Accordingly, the clutch connected state can be reliably changed to the two-clutch disconnected state, and responsiveness of the second piston  33  when the second wet clutch C 2  is disconnected can be improved. 
         [0084]    After a sleeve is moved in the two-clutch disconnected state, when the first wet clutch C 1  is connected, the valve control part  81  may control the first hydraulic pressure regulation valve  101  such that the hydraulic pressure supplied to the first hydraulic chamber  25 A and the second centrifugal hydraulic canceling chamber  35 B via the first downstream supply line  50  is increased from the given hydraulic pressure. 
         [0085]    While the present invention has been described on the basis of the embodiments, the present invention is not limited to the contents of the embodiments, and can also be appropriately modified without departing from the present invention. That is, it goes without saying that other embodiments, examples, and operating techniques carried out by those skilled in the art on the basis of this embodiment are included, in the scope of the present invention. 
         [0086]    For example, in the embodiments, the dual clutch apparatus  10 ,  90  or  100  is connected to the dual clutch type transmission  1  illustrated in  FIGS. 1 and 2 , but may be connected to a dual clutch type transmission with another structure. For example, the dual clutch type transmission  1  may be a dual clutch type transmission in which the first wet clutch C 1  corresponds to the even numbered stages and the second wet clutch C 2  corresponds to the odd numbered stages. 
       DESCRIPTION OF REFERENCE NUMERALS AND CHARACTERS 
       [0087]      10 ,  90 ,  100 : dual clutch apparatus 
         [0088]      11 : clutch input shaft 
         [0089]      12 A: first transmission input shaft 
         [0090]      12 B: second transmission input shaft 
         [0091]      20 : clutch hub 
         [0092]      21 A: first inner plate (first plate) 
         [0093]      21 B: first outer plate (first plate) 
         [0094]      23 : first piston 
         [0095]      25 A: first hydraulic chamber 
         [0096]      25 B: first centrifugal hydraulic canceling chamber (first hydraulic canceling chamber) 
         [0097]      26 : first return spring (first spring) 
         [0098]      31  A: second outer plate (second plate) 
         [0099]      31 B: second inner plate (second plate) 
         [0100]      33 : second piston 
         [0101]      35 A: second hydraulic chamber 
         [0102]      35 B: second centrifugal hydraulic canceling chamber (second hydraulic canceling chamber) 
         [0103]      36 : second return spring (second spring) 
         [0104]      40 : hydraulic pressure circuit 
         [0105]      43 : first upstream supply line (first supply line) 
         [0106]      45 : second upstream supply line (second supply line) 
         [0107]      50 : first downstream supply line (first supply line) 
         [0108]      50 A: first hydraulic chamber-purpose line 
         [0109]      50 B: second canceling chamber-purpose line 
         [0110]      51 : second downstream supply line (second supply Sine) 
         [0111]      51 A: second hydraulic chamber-purpose line 
         [0112]      51 B: first canceling chamber-purpose line 
         [0113]      60 : first electromagnetic valve (first valve) 
         [0114]      65 : second electromagnetic valve (second valve) 
         [0115]      80 : electronic control unit (valve control unit, time counting unit) 
         [0116]      81 : valve control part (valve control trait) 
         [0117]      82 : time counting part (time counting unit) 
         [0118]      91 : rotating speed sensor (rotating speed detecting unit) 
         [0119]      101 : first hydraulic pressure regulation valve (first valve) 
         [0120]      102 : second hydraulic pressure regulation valve (second valve)