Infinite speed ratio continuously variable transmission

• US 6,659,901 B2
• Filed: 03/30/2001
• Issued: 12/09/2003
• Est. Priority Date: 03/30/2000
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Sakai, Hiromasa, Oshidari, Toshikazu
• Primary Examiner(s): Lavinder, Jack
• Assistant Examiner(s): King, Bradley T
• Application Number:
  US09/821,688
• Publication Number:
  US 20010041640A1
• Time in Patent Office: 984 Days
• Field of Search: 475/207, 475/208, 475/209, 475/211, 475/215, 475/218, 477/39
• US Class Current: 475/218
• CPC Class Codes: F16H 2037/088 Power split variators with summing differentials, with the input of the CVT connected or connectable to the input shaft
• CPC Class Codes: F16H 37/084 at least one power path being a continuously variable transmission, i.e. CVT
• CPC Class Codes: F16H 37/086 CVT using two coaxial friction members cooperating with at least one intermediate friction member
• CPC Class Codes: F16H 61/6648 controlling of shifting being influenced by a signal derived from the engine and the main coupling

Abstract

A three-way clutch unit (9) comprising a forward clutch (91), second clutch (92) and forward one way clutch (93) which sets a power recirculation mode, a high clutch (10) which sets a direct mode, and a mode change-over valve (175) which supplies an oil pressure to one of the high clutch (10) and second clutch (92), are provided.

Claims

1. An infinite speed ratio continuously variable transmission for a vehicle, comprising:

a continuously variable transmission which can vary speed ratio continuously and has a geared neutral point which is a speed ratio making a unit output shaft stationary,

a fixed speed ratio transmission,

a unit input shaft which connects to input side of the continuously variable transmission and the fixed speed ratio transmission,

said unit output shaft which connects to output side of the continuously variable transmission and the fixed speed ratio transmission via a planetary gear set,

a first clutch device interposed between the fixed speed ratio transmission and the planetary gear set, which sets a power recirculation mode,

a second clutch device interposed between the continuously variable transmission and the unit output shaft, which sets a direct mode,

a clutch control unit which controls the power recirculation mode and the direct mode by selectively engaging the first clutch device and the second clutch device,

a switch which commands a forward running of the vehicle, and

a sensor which detects the speed ratio of the continuously variable transmission or an overall speed ratio of the infinite speed ratio continuously variable transmission,

wherein at least one of the first clutch device and the second clutch device is provided with a one way clutch, a first clutch interposed in series to the one way clutch and a second clutch which is provided in parallel to the one way clutch, the first clutch and the one way clutch being arranged to cooperate to transmit torque in only one direction, the second clutch functioning to transmit torque in both directions, and

the clutch control unit permits engaging only one of the first clutch device and the second clutch device when both the first clutch device and the second clutch device can transmit torque in both directions, and arranged to engage the first clutch at all times when the forward running of the vehicle is specified and to prohibit the engaging of the second clutch when the speed ratio of the continuously variable transmission coincides with the geared neutral point.

2. The infinite speed ratio continuously variable transmission as defined in claim 1, wherein the first clutch device comprises the one way clutch, the first clutch and the second clutch, and the second clutch device comprises a high clutch which functions to transmit torque in both directions.

3. The infinite speed ratio continuously variable transmission as defined in claim 1, wherein the clutch control unit comprises:

a first hydraulic supply device which supplies an oil pressure to engage the first clutch at all times when the forward running of the vehicle is specified,

a second hydraulic supply device which supplies an oil pressure to engage the second clutch, and

a third hydraulic supply device which supplies an oil pressure to engage the high clutch,

wherein the clutch control unit is arranged to permit the second hydraulic supply device to supply oil pressure to engage the second clutch while prohibiting the third hydraulic supply device from supplying oil pressure to engage the high clutch when the forward running of the vehicle is specified and engine brake is required, and to permit the third hydraulic supply device to supply oil pressure to engage the third clutch while prohibiting the second hydraulic supply device from supplying oil pressure to engage the second clutch when the forward running of the vehicle is specified and the direct mode is set.

4. The infinite speed ratio continuously variable transmission as defined in claim 3, wherein the clutch control unit comprises a mode change-over valve which selectively supplies oil pressure to the other of the second clutch and the high clutch according to an energization state of a first actuator, and a second actuator which controls oil pressure supplied by the second hydraulic supply device to the second clutch via the mode change-over valve.

5. The infinite speed ratio continuously variable transmission as defined in claim 4, wherein the clutch control unit further comprises a third actuator which controls oil pressure supplied by the third hydraulic supply device to the high clutch via the mode change-over valve.

6. The infinite speed ratio continuously variable transmission as defined in claim 4, wherein the mode change-over valve comprises a valve body pushed by an elastic member, the elastic member holding the valve body when the first actuator is not energized at a position at which the mode change-over valve supplies oil pressure to the high clutch while releasing oil pressure of the second clutch to the atmosphere.

7. The infinite speed ratio continuously variable transmission as defined in claim 4, wherein the second actuator is arranged to, when not energized, interrupt or reduce the oil pressure supply of the second hydraulic supply device to the second clutch via the mode change-over valve.

8. The infinite speed ratio continuously variable transmission as defined in claim 5, wherein the third actuator is arranged to, when not energized, interrupt or reduce the oil pressure supply of the third hydraulic supply device to the high clutch via the mode change-over valve.

9. The infinite speed ratio continuously variable transmission as defined in claim 1, wherein the clutch control unit comprises a mode change-over valve which selectively supplies oil pressure to one of the second clutch and the high clutch while prohibiting supply of oil pressure to the other of the second clutch and the high clutch according to an energization state of a first actuator, and is arranged to supply oil pressure for engaging the first clutch to the high clutch when the mode change-over valve is changed-over to supply of oil pressure to the high clutch while prohibiting supply of oil pressure to the second clutch.

10. The infinite speed ratio continuously variable transmission as defined in claim 4, wherein the mode change-over valve is arranged to release the oil pressure of the high clutch to the atmosphere when the first actuator is not energized.