Continuously variable dual mode transmission

• US 20060234822A1
• Filed: 03/27/2006
• Published: 10/19/2006
• Est. Priority Date: 04/15/2005
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Oliver, James L., Morscheck, Timothy J., Reynolds, Joseph D., Stine, Alan C.
• Granted Patent: US 7,473,202 B2
• Time in Patent Office: Days
• US Class Current: 475/211
• 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 2037/0886 with switching means, e.g. to change ranges
• CPC Class Codes: F16H 2061/6601 with arrangements for dividing torque and shifting between different ranges
• CPC Class Codes: F16H 2300/14 Selecting a state of operation, e.g. depending on two wheel or four wheel drive mode
• CPC Class Codes: F16H 37/0833 with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths F16H3/72 takes precedence
• CPC Class Codes: F16H 37/0846 CVT using endless flexible members
• CPC Class Codes: F16H 61/66259 using electrical or electronical sensing or control means

Abstract

A dual mode continuously variable transmission for use with motor vehicles includes a transmission input shaft, a transmission output shaft, and a variator disposed between the transmission input shaft and the transmission output shaft. A mixer gear set is operably disposed between the transmission input shaft and the variator output shaft. A clutching element is operably disposed between the input shaft the mixer gear set. The variator is configured to continuously vary a ratio of input torque to output torque between the variator shafts responsive to commands from an electronic control unit. The variator input shaft is drivingly connected to the input shaft and the variator output shaft is drivingly connected to the output shaft. The clutching element selectively connects and disconnects the input shaft and the mixer gear set to operate the transmission in a power splitting mode of operation and a variator only mode of operation. An electronic control unit incorporates logic rules by which the clutching element maintains the transmission in a variator-only mode of operation in a first vehicle speed range, and maintains the transmission in a power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range.

Claims

1. A dual mode continuously variable transmission for use with motor vehicles comprising:

a transmission input shaft;

a transmission output shaft;

a variator disposed between the transmission input shaft and the transmission output shaft and the variator having a variator input shaft and a variator output shaft and configured to continuously vary a ratio of input torque to output torque between the variator shafts responsive to commands from an electronic control unit, the variator input shaft drivingly connected to the input shaft and the variator output shaft drivingly connected to the output shaft;

a mixer gear set operably disposed between the transmission input shaft and the variator output shaft;

a clutching element operably disposed between the transmission input shaft and the mixer gear set and configured to selectively connect and disconnect the input shaft and the mixer gear set to thereby selectively operate the transmission in a power splitting mode of operation and to operate the transmission in a variator-only mode of operation; and

the electronic control unit operably connected to the variator and operably connected to the clutching element and configured to include logic rules for controlling the transmission, the logic rules including rules by which the clutching element maintains the transmission in the variator-only mode of operation in a first vehicle speed range and maintains the transmission in a power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range.

2. A dual mode continuously variable transmission as claimed in claim 1 wherein the first vehicle speed range is characterized as a launch range and the second vehicle speed range is characterized as a cruise range.

3. A dual mode continuously variable transmission as claimed in claim 1 further comprising:

an input fixed ratio element configured to reduce the torque from the input gear set to the variator and operably disposed between the input gear set and the variator input shaft; and

an output fixed ratio element configured to increase the torque from the variator and operably disposed between the variator output shaft and the gear unit input shaft.

4. A dual mode continuously variable transmission as claimed in claim 1 wherein the mixer gear set is a planetary mixer gear set including as elements thereof:

a ring gear rotatable about a first axis;

a sun gear rotatable about the first axis; and

a carrier rotatable about the first axis with a plurality of planet gears in mesh with both the sun gear and the ring gear,

wherein the planetary mixer gear set is drivingly connected by a first of its elements to at least a portion of the clutching mechanism, by a second of its elements to the transmission output shaft, by a third of its elements to the variator output shaft.

5. A dual mode continuously variable transmission as claimed in claim 4 wherein the transmission includes a grounded element selectively engaged by the clutching element further wherein with such engagement the first of the mixer gear set elements prevented from rotating about the first axis when the grounded element is engaged by the clutching element.

6. A dual mode continuously variable transmission as claimed in claim 1 wherein the transmission includes a grounded element selectively engaged by the clutching element further wherein with such engagement the first of the mixer gear set elements is prevented from rotating about the first axis when the grounded element is engaged by the clutching element.

7. A dual mode continuously variable transmission for use with motor vehicles comprising:

a transmission input shaft;

a transmission output shaft;

a variator disposed between the transmission input shaft and the transmission output shaft and the variator having a variator input shaft and a variator output shaft and configured to continuously vary a ratio of input torque to output torque between the variator shafts responsive to commands from an electronic control unit, the variator input shaft drivingly connected to the transmission input shaft and the variator output shaft drivingly connected to the transmission output shaft;

a planetary mixer gear set operably disposed between the transmission input shaft and the variator output shaft including a ring gear rotatable about a first axis, a sun gear rotatable about the first axis and drivingly connected to the variator output shaft, and a carrier drivingly connected to the transmission output shaft and rotatable about the first axis with a plurality of planet gears in mesh with both the sun gear and the ring gear;

a grounded element rotatively fixed relative to a transmission housing;

a first clutching device operably disposed between the transmission input shaft and the ring gear and configured to selectively connect the input shaft with the ring gear to achieve a power splitting mode of operation;

a second clutching device operably disposed between the ring gear and the grounded element and configured to selectively connect the ring gear and the grounded element to achieve a variator-only mode of operation; and

the electronic control unit operably connected to the variator and operably connected to the clutching elements and configured to include logic rules for controlling the transmission, the logic rules including rules by which the clutching element maintains the transmission in the variator-only mode of operation in a first vehicle speed range and maintains the transmission in the power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range.

8. A dual mode continuously variable transmission as claimed in claim 7 wherein the first and second clutching devices include a single jaw clutch selectively engaging the grounded element in a first direction of displacement and engaging the input shaft in a second direction of displacement.

9. A dual mode continuously variable transmission as claimed in claim 7 wherein the first and second clutching devices are integrated into a mode clutch mechanism having a first brake and a second brake for selectively engaging the grounded element and the input shaft respectively.

10. A dual mode continuously variable transmission as claimed in claim 7 wherein the transmission further includes a connecting shaft to which the ring gear is fixed and to which both the first and the second clutching devices are fixed, the first and second clutching devices being axially separate from each other.

11. A dual mode continuously variable transmission as claimed in claim 7 wherein a planetary locking clutch selectively locks the sun gear to the carrier for unitary rotation thereof.

12. A dual mode continuously variable transmission as claimed in claim 7 having both a forward drive gear set and a reverse drive gear set disposed between the variator output shaft and the sun gear wherein a clutching mechanism is configured to selectively provide a driving connection between the variator output shaft and the sun gear through one of the forward drive gear set and the reverse drive gear set.

14. A dual mode continuously variable transmission as claimed in claim 7 wherein a first stage gear set is disposed between the sun gear and a countershaft and a second stage gear set is disposed between the countershaft and the transmission output shaft, and a clutch is configured and disposed to provide driving engagement between one of the first stage and the second stage gear sets and their associated shafts.

15. A dual mode continuously variable transmission as claimed in claim 7 wherein a first stage reverse gear set is disposed between the variator output shaft and an idler shaft and a second stage reverse gear set is disposed between the idler shaft and the transmission output shaft, and a clutch is configured and disposed to provide driving engagement between one of the first stage and the second stage reverse gear sets and their associated shafts.

13. A dual mode continuously variable transmission for use with motor vehicles comprising:

a transmission input shaft;

a transmission output shaft;

a variator disposed between the transmission input shaft and the transmission output shaft and the variator having a variator input shaft and a variator output shaft and configured to continuously vary a ratio of input torque to output torque between the variator shafts responsive to commands from an electronic control unit, the variator input shaft drivingly connected to the transmission input shaft and the variator output shaft drivingly connected to the transmission output shaft;

a planetary mixer gear set operably disposed between the transmission input shaft and the variator output shaft including a ring gear rotatable about a first axis, a sun gear rotatable about the first axis and drivingly connected to the variator output shaft, and a carrier drivingly connected to the transmission output shaft and rotatable about the first axis with a plurality of planet gears in mesh with both the sun gear and the ring gear;

a connecting shaft fixed to the ring gear for unitary rotation therewith;

a first clutching device operably disposed between the connecting shaft and a transmission housing selectively connecting the connecting shaft to the housing to prevent relative rotation therebetween to achieve a variator-only mode of operation;

a countershaft having a counter gear fixed thereto in mesh with an input shaft gear fixed to the transmission input shaft and the countershaft also having a forward drive gear fixed thereto in mesh with a forward driven gear rotatably disposed on the connecting shaft;

a second clutching device selectively rotatively fixing the forward drive gear to the connecting shaft to achieve a power splitting mode of operation; and

the electronic control unit operably connected to the variator and operably connected to the clutching devices and configured to include logic rules for controlling the transmission, the logic rules including rules by which the clutching devices maintain the transmission in the variator-only mode of operation in a first vehicle speed range and maintain the transmission in the power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range.

16. A control system for a dual mode continuously variable transmission for use with motor vehicles comprising in which the transmission includes:

a transmission input shaft;

a transmission output shaft;

a variator disposed between the transmission input shaft and the transmission output shaft and the variator having a variator input shaft and a variator output shaft and configured to continuously vary a ratio of input torque to output torque between the variator shafts responsive to commands from an electronic control unit, the variator input shaft drivingly connected to the transmission input shaft and the variator output shaft drivingly connected to the transmission output shaft;

a planetary mixer gear set operably disposed between the transmission input shaft and the variator output shaft including a ring gear rotatable about a first axis, a sun gear rotatable about the first axis and drivingly connected to the variator output shaft, and a carrier drivingly connected to the transmission output shaft and rotatable about the first axis with a plurality of planet gears in mesh with both the sun gear and the ring gear;

a connecting shaft fixed to the ring gear for unitary rotation therewith; and

a first clutching device operably disposed between the connecting shaft and a transmission housing selectively connecting the connecting shaft to the housing to prevent relative rotation therebetween to achieve a variator-only mode of operation;

a countershaft having a counter gear fixed thereto in mesh with an input shaft gear fixed to the transmission input shaft and the countershaft also having a forward drive gear fixed thereto in mesh with a forward driven gear rotatably disposed on the connecting shaft;

a second clutching device selectively rotatively fixing the forward drive gear to the connecting shaft to achieve a power splitting mode of operation, the control system comprising;

the electronic control unit being operably connected to the variator and to the clutching devices; and

the electronic control unit configured to include logic rules for controlling the transmission, the logic rules including rules by which the clutching devices maintain the transmission in the variator-only mode of operation in a first vehicle speed range and maintain the transmission in the power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range.

17. A control system for a dual mode continuously variable transmission as claimed in claim 16 wherein the gear unit is configured to provide forward drive ratios which in combination with the variator provide final drive ratios which overlap by approximately fifty percent to enable the control unit a high degree of flexibility in selecting the vehicle speed at which to execute a shift between forward drive ratios.

18. A control system for a dual mode continuously variable transmission for use with a motor vehicle, the transmission including

a transmission shaft,

a transmission output shaft,

a variator operably disposed between the transmission input shaft and the transmission output shaft and the variator having a variator input shaft and a variator output shaft,

a multi-speed gear unit having an input element and an output element and the multi-speed gear unit incorporating a plurality of gearing elements providing a plurality of forward drive ratios and a plurality of drive ratio clutching elements selectively engaging predetermined members of the gearing elements to provide associated predetermined forward drive ratios and operably disposed between the transmission input shaft and the transmission output shaft,

a mixer gear set operably disposed between the transmission output shaft and the variator output shaft and the gear unit output element,

a power mode clutching element operably disposed between the transmission input shaft and the mixer gear set and selectively connecting and disconnecting the input shaft and the mixer gear set to operate the transmission in a power splitting mode of operation and to operate the transmission in a variator only mode of operation,

the control system comprising:

an electronic control unit operably connected to the variator and to the gear unit clutching elements and to the power mode clutching element and configured to include logic rules for controlling the transmission, the logic rules including rules by which;

the transmission is in a variator-only mode of operation in a first vehicle speed range and maintains the transmission in a power splitting mode of operation in a second vehicle speed range greater than the first vehicle speed range; and

once in the power splitting mode, the transmission is shifted between forward drive ratios to enable maintaining constant engine speed while subjecting the variator to only part of the power being used to propel the vehicle in a forward direction