Continuously variable transmission apparatus

• US 7,160,220 B2
• Filed: 07/14/2004
• Issued: 01/09/2007
• Est. Priority Date: 07/14/2003
• Status: Expired due to Fees

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Inoue, Eiji, Shinojima, Takumi
• Primary Examiner(s): HO, HA DINH
• Application Number:
  US10/890,240
• Publication Number:
  US 20050037887A1
• Time in Patent Office: 909 Days
• Field of Search: 475/208, 475/216, 477/37, 477/41
• US Class Current: 475/208
• CPC Class Codes: F16H 2037/0886 with switching means, e.g. to change ranges
• 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
• CPC Class Codes: F16H 61/6649 characterised by the means for controlling the torque transmitting capability of the gearing

Abstract

A continuously variable transmission apparatus includes: an input shaft, an output shaft, a toroidal continuously variable transmission, a gear-type differential unit including a plurality of gears, and a controller. The controller calculates a torque actually passing through the toroidal continuously variable transmission to obtain a deviation of the torque from a target value and adjusts a transmission ratio of the toroidal continuously variable transmission to eliminate the deviation. The controller stops the adjustment of the transmission ratio when the torque is not stable.

Claims

1. A continuously variable transmission apparatus, comprising:

an input shaft rotated and driven by a driving source;

an output shaft;

a toroidal continuously variable transmission;

a gear-type differential unit including a plurality of gears; and

a controller for controlling change of a transmission ratio of the toroidal continuously variable transmission;

wherein

the toroidal continuously variable transmission comprises;

an input disc rotated and driven by the input shaft,

an output disc supported so as to be relatively rotatable with respect to the input disc,

a plurality of power rollers interposed between the input disc and the output disc,

a plurality of support members rotatably supporting the respective power rollers, and

an actuator having a pair of oil pressure chambers and displacing the support members so as to change the transmission ratio between the input disc and the output disc;

the differential unit comprises;

a first input portion rotated and driven by the input shaft together with the input disc, and

a second input portion connected to the output disc, wherein

a rotational movement which is obtained in accordance with a speed differential between the first and the second input portions is taken out and transmitted to the output shaft; and

the controller performs the following functions (1) through (3);

(1) a function of adjusting the transmission ratio of the toroidal continuously variable transmission so as to change a relative displacement speed of the plurality of gears contained in the gear-type differential, thereby converting a rotational condition of the output shaft between a forward-rotating condition and a reverse-rotating condition through a non-rotating condition while the input shaft continues rotating in a single direction;

(2) a function of measuring a differential pressure between a pair of chambers constituting an actuator so as to calculate a torque actually passing through the toroidal continuously variable transmission;

thereafter obtaining a deviation, from a target value, of the torque actually passing through the toroidal continuously variable transmission; and

thereby adjusting the transmission ratio of the toroidal continuously variable transmission so that the torque passing through a toroidal continuously variable transmission attains the target value, and

(3) a function of stopping the above function (2) in the case where the torque passing through the toroidal continuously variable transmission fails to become stable.

2. The continuously variable transmission apparatus according to claim 1, wherein

the torque applied on the input shaft by the driving source changes depending on a rotation speed;

and

the rotation speed of the driving source is roughly controlled, and the transmission ratio of the toroidal continuously variable transmission is set to a value assumed to be necessary for matching the controlled rotation speed of the driving source to a rotation speed of the input shaft so as to realize function (2) of the controller.

3. The continuously variable transmission apparatus according to claim 1, further comprising:

a clutch which transmits a rotational movement when connected, wherein

a case where the torque passing through the toroidal continuously variable transmission which is specified in function (3) of the controller fails to become stable corresponds to the case where the clutch is disengaged in response to selection of a non-travel state.

4. The continuously variable transmission apparatus according to claim 2, further comprising:

a clutch which transmits a rotational movement when connected, wherein

a case where the torque passing through the toroidal continuously variable transmission specified in function (3) of the controller fails to become stable corresponds to the case where the clutch is disengaged in response to selection of a non-travel state.

5. The continuously variable transmission apparatus according to claim 1, wherein

the function (2) of the controller is ceased until elapse of a predetermined period of time after selection of a travel state during a non-travel state.

6. The continuously variable transmission apparatus according to claim 2, wherein

the function (2) of the controller is ceased until elapse of a predetermined period of time after selection of a travel state during a non-travel state.

7. The continuously variable transmission apparatus according to claim 3, wherein

the function (2) of the controller is ceased until elapse of a predetermined period of time after selection of a travel state during a non-travel state.

8. The continuously variable transmission apparatus according to claim 4, wherein

the function (2) of the controller is ceased until elapse of a predetermined period of time after selection of a travel state during a non-travel state.

9. The continuously variable transmission apparatus according to claim 1, wherein

the function (2) of the controller is ceased in the case where a pressure differential of a the pair of oil pressure chambers is equal to a predetermined value or less.

10. The continuously variable transmission apparatus according to claim 2, wherein

the function (2) of the controller is ceased in the case where a pressure differential of a the pair of oil pressure chambers is equal to a predetermined value or less.

11. The continuously variable transmission apparatus according to claim 3, wherein

the function (2) of the controller is ceased in the case where a pressure differential of a the pair of oil pressure chambers is equal to a predetermined value or less.

12. The continuously variable transmission apparatus according to claim 4, wherein

the function (2) of the controller is ceased in the case where a pressure differential of a the pair of oil pressure chambers is equal to a predetermined value or less.

13. The continuously variable transmission apparatus according to claim 1, further comprising:

a load-detecting unit that detects a load of the driving source;

wherein the function (2) of the controller is ceased after selection of a travel state during a non-travel state, until the load-detecting unit detects an increase in a load of the driving source.

14. The continuously variable transmission apparatus according to claim 2, further comprising:

a load-detecting unit that detects a load of the driving source;

wherein the function (2) of the controller is ceased after selection of a travel state during a non-travel state, until the load-detecting unit detects an increase in a load of the driving source.

15. The continuously variable transmission apparatus according to claim 3, further comprising:

a load-detecting unit that detects a load of the driving source;

wherein the function (2) of the controller is ceased after selection of a travel state during the non-travel state, until the load-detecting unit detects an increase in a load of the driving source.

16. The continuously variable transmission apparatus according to claim 4, further comprising:

a load-detecting unit that detects a load of the driving source;

wherein the function (2) of the controller is ceased after selection of a travel state during the non-travel state, until the load-detecting means unit an increase in a load of the driving source.