Control apparatus for a multi-speed transmission

A power transmission employs a plurality of torque-to-thrust apparatus to control the engagement and disengagement of the transmission ratios. Each of the torque-to-thrust apparatus is operatively connectible with a pair of electric motors, which are individually operable to control the operation of the torque-to-thrust apparatus. During transmission operation, one of the electric motors is operable to disengage a friction device within the transmission while the other electric motor is operable to engage a different friction device within the transmission, thus permitting controlled ratio upshifts and downshifts.

TECHNICAL FIELD

This invention relates to control apparatus for power transmissions and, more particularly, to control apparatus employing torque-to-thrust control mechanisms.

BACKGROUND OF THE INVENTION

Prior art automatic power transmissions generally include control apparatus having a hydraulic power source in valve mechanisms for controlling a plurality of friction devices that are applied by hydraulic power to associated pistons. While these control apparatus work quite well and have been very successful over the years, they do require the addition of mechanisms within the power transmission that require space and also induce a degree of temperature rise to the operation of the power transmission. While all of the fluid mechanisms of the power transmission may not be eliminated, the fluid passages, except for lubrication passages, within the main mechanical components of the power transmission can be eliminated.

The fluid-operated devices of power transmission controls can be supplanted with torque-to-thrust mechanisms such as those shown in U.S. Ser. No. 10/303,245 filed Nov. 25, 2002; U.S. Ser. No. 10/319,957 filed Dec. 16, 2002; and U.S. Ser. No. 10/946,759, filed Sep. 22, 2004, all of which are assigned to the assignee of the present application.

SUMMARY OF THE INVENTION

It is an object of this invention to provide control apparatus for a power transmission employing a plurality of torque-to-thrust mechanisms, which are controlled by electric motors.

In one aspect of the present invention, two electric drive motors are employed to control the operation of at least five torque-to-thrust apparatus.

In another aspect of the present invention, each of the torque-to-thrust apparatus is selectively connectible with both of the drive motors individually through selectively engageable friction devices.

In yet another aspect of the present invention, each of the torque-to-thrust apparatus is selectively held stationary by friction devices.

In yet still another aspect of the present invention, one of the electric motors is operable through selection of the friction devices to enforce the engagement operation of one of the torque-to-thrust apparatus while the other of the electric motors is selectively operable through selective engagement of the friction devices to disengage one of the torque-to-thrust apparatus.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

As seen inFIG. 1, there is a multi-speed transmission represented by a block10, which is surrounded by a plurality of torque-to-thrust control apparatus or mechanisms12,14,16,18, and20. The torque-to-thrust apparatus12includes a rotary input mechanism22, which is driven by a gear member24, as seen inFIG. 1. The torque-to-thrust apparatus14includes a rotary input mechanism26, which is driven by a gear member28. The torque-to-thrust apparatus16includes a rotary input mechanism30, which is driven by a gear member32. The torque-to-thrust apparatus18includes a rotary input mechanism34, which is driven by a gear member36. The torque-to-thrust apparatus20includes a rotary input mechanism38, which is driven by a gear member40.

The gears members24,28,32,36, and40are all rotatably supported on a main shaft42. The shaft42is drivingly connected with a selectively operable electric motor44. The electric motor44is a conventional electric drive device, which can be controlled for clockwise and counterclockwise rotation. Such mechanisms are well known in the art.

The gear member24is selectively connectible with the shaft42by a conventional selectively operated or solenoid-controlled clutch46. The gear member24can be selectively engaged or restrained by a stationary housing48through a conventional solenoid or electrically operated brake apparatus50.

The gear member28is selectively connectible with the shaft42through a selectively engageable clutch52and with the housing48through a selectively engageable brake54. The gear member32is selectively connectible with the shaft42through a selectively engageable clutch mechanism56and with the housing48through a selectively engageable brake member58. The gear member36is selectively connectible with the shaft42through a clutch member60and selectively connectible with the housing48through a brake member62. The gear member40is selectively connectible with the shaft42through a clutch apparatus or mechanism64and selectively connectible with the housing48through a conventional brake apparatus66.

The rotary input mechanisms22,26,30,34, and38are also engaged by respective gears24A,28A,32A,36A, and40A. These gears are selectively connectible with a shaft42A, which is driven by a conventional electric motor44A.

The gear member24A is selectively connectible through a clutch46A with the shaft42A. The gear member28A is selectively connectible with the shaft42A through a selectively engageable clutch52A. The gear member32A is selectively connectible with the shaft42A through a selectively engageable clutch56A. The gear member36A is selectively connectible with the shaft42A through a clutch60A. The gear member40A is selectively connectible with the shaft42A through a selectively engageable clutch64A.

The systems operated by the motors44and44A are substantially identical and are not necessarily spaced as shown schematically on opposite sides of the transmission block10but rather spaced on one side of the transmission and as shown inFIG. 2. The electric motor44is operable to selectively control one of the torque-to-thrust apparatus through the engagement of the appropriate clutch member such that the torque-to-thrust apparatus can be rotated by the motor44. Each of the torque-to-thrust apparatus is also selectively controlled or operable by the electric motor44A through the engagement of the appropriate clutch apparatus.

During transmission operation, one of the friction devices within the transmission will be engaged while another is being disengaged. The electric motor44will control one of the friction members within the transmission while the electric motor44A controls another of the friction devices within the transmission.

There is shown inFIG. 3a power transmission10A having an input shaft70, a planetary gear arrangement72, and an output shaft74. The planetary gear arrangement72includes a first simple planetary gearset76and a Ravigneaux gearset78.

The planetary gearset76includes a sun gear member80, a ring gear member82, and a planet carrier assembly member84. The planet carrier assembly member84includes a plurality of pinion gear members86that are rotatably mounted on a planet carrier member88and disposed in meshing relationship with both the sun gear member80and the ring gear member82.

The Ravigneaux gearset78includes two sun gear members90and92, a ring gear member94, and a planet carrier assembly member96. The planet carrier assembly member96includes a planet carrier member98on which is mounted a plurality of pinion gears100disposed in meshing relationship with both the sun gear member92and the ring gear member94, and a plurality of intermeshing pinion gear members102and104that are rotatably disposed thereon and meshing with the sun gear member90and the ring gear member94, respectively. The planetary gear arrangement72, as shown inFIG. 3, is well known.

The sun gear member80is continuously connected with a transmission housing106. The ring gear member82is continuously connected with the input shaft70. The planet carrier member88is selectively connectible through a friction device such as a clutch108with the sun gear member90. The input shaft70is selectively connectible through a friction device such as a selectively engageable clutch110to the planet carrier member98. The planet carrier member88is also selectively connectible with the sun gear member92through a conventional friction clutch112and selectively connectible with the transmission housing106through a selectively engageable friction brake114. The planet carrier member98is selectively connectible with the transmission housing106through a selectively engageable friction brake116and also selectively connectible with the transmission housing106through a one-way torque-transmitting mechanism118.

The clutches and brakes of the power transmission10A are manipulated or engaged in combinations of two to establish six forward speed ratios and one reverse speed ratio between the input shaft70and the output shaft74.

To establish the first or lowest forward speed ratio, the clutch108is engaged and either the one-way torque-transmitting mechanism118provides the action or the brake116is engaged to provide the action. To establish the second forward speed ratio, the clutch108is engaged and the brake114is engaged while the brake116is disengaged and the mechanism118is in an overrun condition. To establish the third forward speed ratio, the clutch108is engaged and the clutch112is engaged while the brake114is disengaged.

To establish the fourth forward speed ratio, the clutch108is engaged and the clutch110is engaged while the clutch112is disengaged. To establish the fifth forward speed ratio, the clutch110is engaged and the clutch112is engaged while the clutch108is disengaged. To establish the sixth forward speed ratio, the clutch110is engaged and the brake114is engaged while the clutch112is disengaged. The reverse speed ratio is established with the engagement of the clutch112and the brake116. The clutches and brakes that are not operating in a specific gear ratio are disengaged.

The engagement and disengagement of the clutch108is controlled by the torque-to-thrust mechanism14. The engagement and disengagement of the clutch110is controlled by the torque-to-thrust mechanism12. The engagement and disengagement of the clutch112is controlled by the torque-to-thrust mechanism16. The engagement and disengagement of the brake114is controlled by the torque-to-thrust mechanism18. The engagement and disengagement of the brake116is controlled by the torque-to-thrust mechanism20.

The torque-to-thrust apparatus may take the structure of those described in U.S. Ser. No. 10/303,245 filed Nov. 25, 2002; U.S. Ser. No. 10/319,957 filed Dec. 16, 2002; and U.S. Ser. No. 10/946,759, filed Sep. 22, 2004, all of which are assigned to the assignee of the present application.

As is well known with torque-to-thrust apparatus, when the input portion of the torque-to-thrust apparatus is rotated, the output portion can move axially to apply a thrust force to whatever mechanism is desired to be operated. To engage the clutch108, the clutch52is engaged such that the electric motor44is connected to drive the rotary member26through the gear member28. To engage the clutch108, the electric motor44is rotated and therefore the rotary input mechanism26is rotated resulting in axial movement of the output portion of the torque-to-thrust mechanism14. This will enforce engagement of the clutch108.

The brake member116is controlled in engagement by the torque-to-thrust mechanism20. In order to operate the torque-to-thrust mechanism20, the electric motor44A is connected with the gear40A through the clutch mechanism64A. The electric motor44A is rotated to cause engagement of the brake116. When the clutch108and brake116has been fully engaged the respective rotary devices, which cause that engagement will be maintained stationary by the engagement of their respective brake mechanisms. For example, the clutch108is held in engagement by the engagement of the brake54, which prevents rotation of the rotary input mechanism26. The torque-to-thrust mechanism20is retained in its engaged position by the engagement of the brake66.

When the establishment of the first forward speed ratio has been accomplished, the electric motors44and44A and their respective shafts42and42A are disconnected from the gear members. Thus, the motors can both be manipulated or operated to control the upshift from first to second. During the upshift from first to second, the clutch108remains engaged, the brake mechanism116is disengaged and the brake114is engaged. Since the clutch108no longer needs assistance of either of the electric motors, the electric motor44through the engagement of the clutch60can control the torque-to-thrust mechanism18to thereby control engagement of the brake114.

During engagement of the brake114, the brakes66and116are disengaged by the engagement of the clutch64A and the rotary motion of the motor44A. The motor44A will be rotated in the direction opposite that which was employed during the engagement of the brake116. After completion of the one-to-two ratio or 1–2 interchange, the brake62is engaged and the clutch60is disengaged to maintain engagement of clutch114. Also, when the brake116has been fully disengaged, the clutch64is disengaged.

The second-to-third or 2–3 ratio interchange is accomplished with the disengagement of the brake114and the engagement of the clutch112. The brake114can be disengaged through the control of the torque-to-thrust mechanism18by engaging the clutch60, disengaging the brake62, and rotating the electric motor44in a direction opposite that of engagement. The clutch112is controlled through the torque-to-thrust mechanism16, which is controlled by the electric motor44A through the clutch56A and gear member28A. Upon the completion of the ratio interchange, that is the full engagement of clutch112and disengagement of brake114, the brake58is engaged to ensure the continued engagement of the clutch116and the shaft42is disengaged from the rotary input mechanism34through the disengagement of the clutch60.

To accomplish a third-to-fourth or 3–4 ratio interchange, the clutch112is disengaged while the clutch110is engaged. The disengagement of the clutch112is controlled by the electric motor44A through the engagement of the clutch56A and disengagement of the brake58, and the engagement of the clutch110is controlled by the torque-to-thrust mechanism12through the engagement of the clutch46and the rotation of the electric motor44. When the 3–4 interchange has been completed, the brake50is engaged to retain the thrust on the torque-to-thrust mechanism12and the clutch56A is disengaged to permit the shaft42A to be freed. Also, the clutch46is disengaged to permit the shaft42to be freed.

It should here be noted that the clutch108was retained in engagement during the first four forward speeds but will be disengaged during the 4–5 ratio interchange. During the fourth-to-fifth or 4–5 ratio interchange, the clutch52is engaged permitting the electric motor44to operate the torque-to-thrust mechanism14and control disengagement of the clutch108. The clutch56A is engaged to permit the electric motor44A to control the engagement of the clutch112. When the clutch52is engaged, the brake54is disengaged. Upon the completion of this ratio interchange, the brake58is engaged and the brake50remains engaged.

To accomplish a fifth-to-sixth or 5–6 ratio interchange, the electric motor44A is selectively connected with the rotary input mechanism30through the engagement of the clutch56such that the torque-to-thrust mechanism16can be operated to disengage the clutch112. When the clutch56A is engaged, the clutch58is disengaged. Also during the 5–6 interchange, the clutch60is engaged to permit the electric motor44to control the torque-to-thrust mechanism18thereby enforcing engagement of the brake114. Upon the completion of the 5–6 interchange, the brake62is engaged, the clutch60is disengaged, and the clutch56A is disengaged.

To provide the downshift sequence, the devices are operated in the opposite manner. The reverse speed ratio is established with the engagement of the clutch64to permit the electric motor44to control the torque-to-thrust mechanism20, and the clutch56A is engaged to permit the electric motor44A to control the engagement and disengagement of the clutch112.

It should be noted that a first forward speed to reverse speed ratio interchange can be accomplished by disengaging the clutch112and engaging the clutch108. This can be accomplished by the electric motor44controlling the engagement of the clutch108through the shaft42and clutch52, and the disengagement of the clutch112through the operation of the clutch56A and the electric motor44A. Either of the motors can be controlled to operate any of the shift devices. It should be appreciated though that the motors can be operated in unison to control the interchange of two devices. Thus, the control apparatus shown in the present embodiment is applicable to any of the transmissions which have single transition shifts. That is, only one friction device is on-coming while only one friction device is off-going to control the ratios within the transmission.

This provides a system which is considerably simpler than having an individual electric motor to control each of the torque-to-thrust mechanisms.

In general, the shift procedure would be:1. Engage the clutch from motor44,44A via shaft42,42A to the gear to the torque to thrust mechanism of the oncoming clutch and the engage the clutch from motor44A,44via shaft42A,42to the gear to the torque to thrust mechanism of the off going clutch.2. Increase the torque on motor44A,44to relieve the load on the clutch grounding the torque to thrust mechanism of the off going clutch.3. Release the clutch that has been grounding the torque to thrust mechanism of the off going clutch.4. Use controlled rotation of motors44and44A to change the thrusts developed by the torque to thrust mechanism on the oncoming and off going clutches in the desired manner to develop a good shift.5. Apply the clutch grounding the gear to the torque to thrust mechanism for the oncoming clutch to maintain that oncoming clutch's capacity.6. Remove all power from motors44and44A.7. Release the clutches connecting the motors44and44A to the thrust mechanisms.

The clutch mechanisms, which are utilized with the electric motor controls44and44A, are very simple devices having low torque requirements. It is considered that the clutches will require a very small torque capacity, for example, one Newton-meter (Nm) and this same torque capacity is also considered appropriate for the brake mechanisms for the control devices. These devices can be electrically or solenoid-operated mechanisms such that there is no requirement for hydraulic fluid except for perhaps lubrication, which is a very low pressure, low flow operation. The clutch and brake devices utilized with the control mechanisms might also be of the mechanical type, which employ solenoid engagement devices.