Abstract:
A dual clutch device includes a first piston applying a first clutch by a hydraulic pressure supplied into a first hydraulic pressure chamber and releasing the first clutch by a first spring, a second piston applying a second clutch by a hydraulic pressure supplied into a second hydraulic pressure chamber and releasing the second clutch by a second spring, a first supply line supplying a hydraulic pressure into the first hydraulic pressure chamber and a second hydraulic pressure canceling chamber, a second supply line supplying a hydraulic pressure into the second hydraulic pressure chamber and a first hydraulic pressure canceling chamber, a first valve allowing or cutting the supply of hydraulic pressure into the first hydraulic pressure chamber and the second hydraulic pressure canceling chamber, and a second valve allowing or cutting the supply of hydraulic pressure into the second hydraulic pressure chamber and the first hydraulic pressure canceling chamber.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a dual clutch device. 
       BACKGROUND ART 
       [0002]    Conventionally, there have been known dual clutch transmissions including a first input shaft connected to a first clutch that is configured to connect and disconnect the transmission of power from an engine and a second input shaft connected to a second clutch that is configured to connect and disconnect the transmission of power from the engine and configured to change a gear ratio by applying the first clutch and the second clutch alternately (for example, refer to Patent Literature 1). 
         [0003]    In a general dual clutch transmission, one clutch corresponds to an odd-numbered gear train and the other clutch to an even-numbered gear train. Owing to this, for example, when effecting an upshift from the second to third gear, the third speed synchromesh mechanism is engaged with the clutch for the even-numbered gear train applied and the second speed synchromesh mechanism engaged. Then, the clutch for the odd-numbered gear train is applied while releasing the clutch for the even-numbered gear train, whereby the change of the gear ratio can be realized without the occurrence of torque loss. 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent Literature 1: JP-A-2010-531417 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    In a general dual clutch device, when applying a clutch, a hydraulic pressure is supplied into a hydraulic pressure chamber, and a hydraulic pressure is released from a hydraulic pressure canceling chamber, causing a piston to move one stroke to bring clutch plates into press contact with one another, whereby the desired application of the clutch is realized. On the contrary, when releasing the clutch, the hydraulic pressure in the hydraulic pressure chamber is released, allowing a return spring in the hydraulic pressure canceling chamber to move the piston away from the clutch plates, whereby the desired release of the clutch is realized. Supplying the hydraulic pressure to the hydraulic pressure chamber or releasing the hydraulic pressure from the hydraulic pressure chamber is controlled by switching on or off solenoid valves provided for the hydraulic pressure chambers. 
         [0006]    Owing to this, for example, in the event that at least one of the solenoid valves fails due to disconnection or sticking, the corresponding clutch is held applied, leading to a risk of triggering a double meshing of the transmission. 
         [0007]    An object of the invention is to provide a dual clutch device which can prevent effectively the double meshing of a transmission. 
       Means for Solving the Problem 
     Solution to Problem 
       [0008]    In order to achieve the above object, a dual clutch device comprises a first clutch comprising a first plate for connecting and disconnecting the transmission of power from an engine to a first transmission input shaft and a second clutch comprising a second plate for connecting and disconnecting the transmission of power from the engine to a second transmission input shaft, the dual clutch device characterized by comprising: a first piston configured to apply the first clutch by pressing the first plate by means of a hydraulic pressure supplied into a first hydraulic pressure chamber and release the first clutch by being moved away from the first plate by a first spring accommodated in a first hydraulic pressure canceling chamber; a second piston configured to apply the second clutch by pressing the second plate by means of a hydraulic pressure supplied into a second hydraulic pressure chamber and release the second clutch by being moved away from the second plate by a second spring accommodated in a second hydraulic pressure canceling chamber; a first supply line for supplying a hydraulic pressure into the first hydraulic pressure chamber and the second hydraulic pressure canceling chamber; a second supply line for supplying a hydraulic pressure into the second hydraulic pressure chamber and the first hydraulic pressure canceling chamber; a first opening-closing valve, which is provided on the first supply line, and which is configured to allow or cut off the supply of a hydraulic pressure into the first hydraulic pressure chamber and the second hydraulic pressure canceling chamber; and a second opening-closing valve, which is provided on the second supply line, and which is configured to allow or cut off the supply of a hydraulic pressure into the second hydraulic pressure chamber and the first hydraulic pressure canceling chamber. 
         [0009]    It may be preferable that a biasing force of the first spring is set greater than a difference between a hydraulic pressure that is supplied into the first hydraulic pressure chamber via the first supply line to be applied on the first piston and a hydraulic pressure that is supplied into the first hydraulic pressure canceling chamber via the second supply line to be applied to the first piston. 
         [0010]    It may be preferable that a biasing force of the second spring is set greater than a difference between a hydraulic pressure that is supplied into the second hydraulic pressure chamber via the second supply line to be applied on the second piston and a hydraulic pressure that is supplied into the second hydraulic pressure canceling chamber via the first supply line to be applied to the second piston. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a schematic vertical longitudinal sectional view showing an upper half of a dual clutch device according an embodiment of the invention. 
           [0012]      FIG. 2  is a diagram illustrating a state in which a first wet type clutch is applied while a second wet type clutch is released in the dual clutch device according to the embodiment of the invention. 
           [0013]      FIG. 3  is a diagram illustrating a state in which the first wet type clutch is released while the second wet type clutch is applied in the dual clutch device according to the embodiment of the invention. 
           [0014]      FIG. 4  is a diagram illustrating hydraulic pressures applied to pistons and biasing forces of return springs in the dual clutch device according to the embodiment of the invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    Hereinafter, a dual clutch device according to an embodiment of the invention will be described based on the accompanying drawings. Like reference numerals are given to like component parts, and this will also be true with names and functions. Consequently, the detailed description of those constituent components will not be repeated in the description. 
         [0016]    As shown in  FIG. 1 , a dual clutch device  10  includes a first wet-type clutch C 1  and a second wet-type clutch C 2 . Reference numeral  11  denotes a clutch input shaft into which power of an engine E is transmitted. Reference numeral  12 A denotes a first transmission input shaft on which a speed change gear train which establishes, for example, odd-numbered gears of a transmission T is provided, and reference numeral  12 B denotes a second transmission input shaft on which a speed change gear train which establishes, for example, even-numbered gears is provided. The second input shaft  12 B is supported rotatably via bearings  13  within a hollow shaft of the first input shaft  12 A. 
         [0017]    The first wet-type clutch C 1  includes a clutch hub  20  which rotates together with the clutch input shaft  11 , a plurality of first inner plates  21 A which are spline fitted in the clutch hub  20 , a first clutch drum  22  which rotates together with the first transmission input shaft  12 A, a plurality of first outer plates  21 B which are disposed alternately between the first inner plates  21 A and which are spline fitted in the first clutch drum  22  and a first cylindrical piston  23  which can press both the plates  21 A,  21 B together in an axial direction. 
         [0018]    The first piston  23  is accommodated slidably within a first annular piston chamber  24  which is defined within the clutch hub  20 . In this first piston chamber  24 , a first hydraulic pressure chamber  25 A and a first centrifugal hydraulic pressure canceling chamber  25 B are defined by the first piston  23 . A first return spring  26 , which is configured to bias the first piston  23  in a direction in which the first piston  23  moves away from the plates  21 A,  21 B, is accommodated within the first centrifugal hydraulic pressure canceling chamber  25 B. Reference sign S denotes a seal member which seals up a gap between the first piston  23  and the first piston chamber  24 . 
         [0019]    When a hydraulic pressure is supplied into the first hydraulic pressure chamber  25 A, the first piston  23  moves one stroke in the axial direction to thereby bring the plates  21 A,  21 B into press contact with one another (the first wet-type clutch C 1 : applied). On the other hand, when the hydraulic pressure within the first hydraulic pressure chamber  25 A decreases and a hydraulic pressure is supplied into the first centrifugal hydraulic pressure canceling chamber  25 B, the first piston  23  is caused to move away from the plates  21 A,  21 B by means of a biasing force of the first return spring  26  and a hydraulic pressure force within the first centrifugal hydraulic pressure canceling chamber  25 B to thereby release the plates  21 A,  21 B from the press contact state (the first wet-type clutch C 1 : released). 
         [0020]    The second wet-type clutch C 2  includes a plurality of second outer plates  31 A which are spline fitted in the clutch hub  20 , a second clutch drum  32  which rotates together with the second transmission input shaft  12 B, a plurality of second inner plates  31 B which are disposed alternately between the second outer plates  31 A and which are spline fitted in the second clutch drum  32 , and a second cylindrical piston  33  which can press and contact both the plates  31 A,  31 B together in the axial direction. 
         [0021]    The second piston  33  is accommodated slidably within a second annular piston chamber  34  which is defined within the clutch hub  20 , In this second piston chamber  34 , a second hydraulic pressure chamber  35 A and a second centrifugal hydraulic pressure canceling chamber  35 B are defined by the second piston  33 . A second return spring  36 , which is configured to bias the second piston  33  in a direction in which the second piston  33  moves away from the plates  31 A,  31 B, is accommodated within the second centrifugal hydraulic pressure canceling chamber  35 B. Reference sign S denotes a seal member which seals up a gap between the second piston  33  and the second piston chamber  34 . 
         [0022]    When a hydraulic pressure is supplied into the second hydraulic pressure chamber  35 A, the second piston  33  moves one stroke in the axial direction to thereby bring the plates  31 A,  31 B into press contact with one another (the second wet-type clutch C 2 : applied). On the other hand, when the hydraulic pressure within the second hydraulic pressure chamber  35 A decreases and a hydraulic pressure is supplied into the second centrifugal hydraulic pressure canceling chamber  35 B, the second piston  33  is caused to move away from the plates  31 A,  31 B by means of a biasing force of the second return spring  36  and a hydraulic pressure within the second centrifugal hydraulic pressure canceling chamber  35 B to thereby release the plates  31 A,  31 B from the press contact state (the second wet-type clutch C 2 : released). 
         [0023]    A hydraulic pressure circuit  40  has a first upstream supply line  43  which connects an oil pan  41  to a first solenoid valve  60  and a second upstream supply line  45  which branches off the first upstream supply line  43  to be connected to a second solenoid valve  65 . An oil pump OP, which is driven by the power of the engine E, is provided on a portion of the first upstream supply line  43  which lies upstream of the branch portion. A lubrication oil supply line  46  on which a throttle valve  47  is provided is connected to the second upstream supply line  45 . 
         [0024]    A first downstream supply line  50  is connected to the first solenoid valve  60 . This first downstream supply line  50  branches into a first hydraulic pressure chamber line  50 A and a second canceling chamber line  50 B within the clutch hub  20 . A downstream end of the first hydraulic pressure chamber line  50 A is connected to the first hydraulic pressure chamber  25 A, and a downstream end of the second canceling chamber line  50 B is connected to the second centrifugal hydraulic pressure canceling chamber  35 B. 
         [0025]    The first solenoid valve  60  is closed by means of a biasing force of a spring  61  when it is deenergized (OFF) and is energized (ON) to be opened by an electronic control unit, not shown. A hydraulic pressure is supplied into the first hydraulic pressure chamber  25 A and the second centrifugal hydraulic pressure canceling chamber  35 B when the first solenoid valve  60  is opened (ON). On the other hand, when the first solenoid valve  60  is closed (OFF), no hydraulic pressure is supplied into the first hydraulic pressure chamber  25 A and the second centrifugal hydraulic pressure canceling chamber  35 B, and the hydraulic pressures within the first hydraulic pressure chamber  25 A and the second centrifugal hydraulic pressure canceling chamber  35 B are returned to the oil pan  41  via a fluid return line  62 . 
         [0026]    A second downstream supply line  51  is connected to a second solenoid valve  65 . This second downstream supply line  51  branches into a second hydraulic pressure chamber line  51 A and a first canceling chamber line  51 B within the clutch hub  20 . A downstream end of the second hydraulic pressure chamber line  51 A is connected to the second hydraulic pressure chamber  35 A, and a downstream end of the first canceling chamber line  51 B is connected to the first centrifugal hydraulic pressure canceling chamber  25 B. 
         [0027]    The second solenoid valve  65  is closed by means of a biasing force of a spring  66  when the second solenoid valve  65  is deenergized (OFF) and is energized (ON) to be opened by the electronic control unit. When the second solenoid valve  65  is opened (ON), a hydraulic pressure is supplied into the second hydraulic pressure chamber  35 A and the first centrifugal hydraulic pressure canceling chamber  25 B. On the other hand, when the second solenoid valve  65  is closed (OFF), no hydraulic pressure is supplied into the second hydraulic pressure chamber  35 A and the first centrifugal hydraulic pressure canceling chamber  25 B, and the hydraulic pressures in the second hydraulic pressure chamber  35 A and the first centrifugal hydraulic pressure canceling chamber  25 B are returned to the oil pan  41  via a fluid return line  67 . 
         [0028]    Next, the application and release of the dual clutch device  10  and the working effect thereof will be described based on  FIGS. 2, 3 . 
         [0029]    When transmitting power from the clutch input shaft  11  to the first transmission input shaft  12 A, as shown in  FIG. 2 , the first wet-type clutch C 1  is applied (the first solenoid valve  60 : ON) and the second wet-type clutch C 2  is released (the second solenoid valve  65 : OFF). 
         [0030]    When the first solenoid valve  60  is ON, since a hydraulic pressure is supplied not only to the first hydraulic pressure chamber  25 A but also to the second centrifugal hydraulic pressure canceling chamber  35 B, both the biasing force of the second return spring  36  and the hydraulic pressure within the second centrifugal hydraulic pressure canceling chamber  35 B are applied to the second piston  33 . As a result, for example, even though a failure such as disconnection or sticking is caused in the second solenoid valve  65 , the second piston  33  can be moved away from the plates  31 A,  31 B in an ensured manner, thereby making it possible to prevent a double meshing of the transmission in an ensured manner. 
         [0031]    When transmitting power from the clutch input shaft  11  to the second transmission input shaft  12 B, as shown in  FIG. 3 , the first wet-type clutch C 1  is released (the first solenoid valve  60 : OFF), and the second wet-type clutch C 2  is applied (the second solenoid valve  65 : ON). 
         [0032]    When the second solenoid valve  65  is ON, since a hydraulic pressure is supplied not only to the second hydraulic pressure chamber  35 A but also to the first centrifugal hydraulic pressure canceling chamber  25 B, both the biasing force of the first return spring  26  and the hydraulic pressure within the first centrifugal hydraulic pressure canceling chamber  25 B are applied to the first piston  23 . As a result, for example, even though a failure such as disconnection or sticking is caused in the first solenoid valve  60 , the first piston  23  can be moved away from the plates  21 A,  21 B in an ensured manner, thereby making it possible to prevent a double meshing of the transmission in an ensured manner. 
         [0033]    Next, how to set an optimal biasing force for the return springs  26 ,  36  will be described based on  FIG. 4 . 
         [0034]    In  FIG. 4 , R A1  denotes an outside diameter of the first piston  23 , R B1  an outside diameter of the first centrifugal hydraulic pressure canceling chamber  25 B, R A2  an outside diameter of the second piston  33 , R B2  an outside diameter of the second centrifugal hydraulic pressure canceling chamber  35 B, P a hydraulic pressure, F S1  a biasing force of the first return spring  26 , and F S2  a biasing force of the second return spring  36 . When these satisfy the following conditional expressions (1), (2), even though both the first and second solenoid valves  60 ,  65  are switched ON at the same time, the first and second wet-type clutches C 1 , C 2  can be released in an ensured manner. 
         [0000]      [Expression 1] 
         [0000]      ( R   A1   2 - R   B1   2 )·π&lt; F   S1 
 
         [0000]      [Expression 2] 
         [0000]      ( R   A2   2 - R   B2   2 )·π&lt; F   S2 
 
         [0035]    In this way, by setting the biasing force of the first return spring  26  greater than a difference in hydraulic pressure between the first hydraulic pressure chamber  25 A and the first centrifugal hydraulic pressure canceling chamber  25 B which is applied to the first piston  23  and setting the biasing force of the second return spring  36  greater than a difference in hydraulic pressure between the second hydraulic pressure chamber  35 A and the second centrifugal hydraulic pressure canceling chamber  35 B which is applied to the second piston  33 , the first and second wet-type clutches C 1 , C 2  are released in an ensured manner, thereby making it possible to prevent effectively the occurrence of a double meshing of the transmission. 
         [0036]    The invention is not limited to the embodiment described heretofore but can be carried out by making modifications thereto as required without departing from the spirit and scope of the invention.