Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-06-07
2001-10-09
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S061000, C701S067000, C192S003290, C192S003330, C475S120000, C475S059000, C475S152000
Reexamination Certificate
active
06301538
ABSTRACT:
TECHNICAL FIELD
The invention relates to a multiple-ratio transmission for an automotive vehicle comprising separate planetary gear units with separate reaction brakes that are applied and released to effect an overall upshifting and downshifting.
BACKGROUND ART
U.S. Pat. No. 5,835,875, filed by the present inventors, which is owned by the assignee of the present invention, discloses a powertrain with planetary gearing, including clutches and brakes that are controlled by a control system with features that are common to the present invention. The transmission of the '875 patent comprises a first compound planetary gear unit with three forward-driving ratios, commonly referred to as a Simpson gearset, and a second gear unit at the torque input side of the first gear unit. Separate pressure-operated clutches and brakes effect upshifting and downshifting. A friction brake for the reaction element of the second gear unit establishes a torque reaction, and an overrunning coupling establishes a torque flow path between two elements of the second gear unit as the friction brake for the second gear unit is released.
Ratio changes in the gearing of the '875 patent are controlled by an electronic microprocessor controller which develops control signals in response to changes in operating variables of the powertrain to actuate four shift solenoids, which in turn control shift valves for actuating and releasing the pressure-operated brakes and clutches.
On a ratio change from the second ratio to the third ratio, it is necessary to exhaust pressure from the apply side of the reaction brake for the second gear unit and from the release side of the reaction brake for the first gear unit. Thus, the brake for the first gear unit becomes applied, and the brake for the second gear unit becomes released in a so-called “swap shift” sequence.
The pressure exhaust flow path for the reaction brake for the first gear unit is combined with a circuit for the clutch for the first gear unit, which is engaged during fourth ratio operation. As the release side of the brake for the first gear unit is depressurized, the apply side of the brake is pressurized. This creates a condition in which a pressure buildup may occur in the clutch because of the common exhaust port for the clutch and the brake located in the clutch circuit. Further, it is necessary in a control system such as that disclosed in the '875 patent to increase the rate of response of the clutch for the first gear unit to commands for clutch engagement and clutch release as ratio changes occur between the fourth ratio and the second ratio or between second ratio and fourth ratio.
DISCLOSURE OF INVENTION
The transmission of the present invention comprises a multiple-ratio Simpson-type gear unit and a simple planetary gear unit arranged in series relationship in an automotive vehicle powertrain. The simple planetary gear unit is located at the torque input side of the multiple-ratio gear unit. A reaction brake for the simple planetary gear unit is applied to effect upshifting of the simple planetary gear unit. An overrunning coupling establishes a one-to-one driving ratio in the simple planetary gear unit when the reaction brake is released.
The multiple-ratio gear unit has a reaction element for anchoring common sun gears of the multiple-ratio gear unit when the transmission is operating in the second forward-driving ratio. When the transmission is operating in the fourth forward-driving ratio, a pressure-operated friction clutch for the multiple-ratio gear unit is applied as the companion brake is released.
An upshift from the second ratio to the third ratio is achieved by disengaging the brake for the simple planetary gear unit and applying the brake for the multiple-ratio gear unit. This is a so-called reaction brake interchange, which effects the swap shift.
The 2-3 upshift occurs in two steps: an intermediate step and a final step. The intermediate step is effected by applying the reaction brake for the multiple-ratio gear unit. The final step occurs at a later instant as the reaction brake for the simple planetary gear unit is applied. During the intermediate step, the brake decelerates the sun gears for the multiple-ratio gear unit, thereby managing the rotary inertia forces so that the 2-3 upshift can occur with minimal inertia torque disturbance.
In order to avoid drift-on of the clutch used to effect fourth ratio operation, a separate fluid pressure exhaust circuit for the reaction brake of the multiple-ratio gear unit and an independent pressure distributor circuit for the clutch are provided. Thus, the clutch does not experience a pressure buildup (or a drift-on condition) as fluid is exhausted from the release side of the brake during the intermediate step of the 2-3 upshift sequence.
The exhaust circuit for the clutch that is engaged during fourth ratio operation includes an exhaust port located in a pressure modifier valve. The pressure modifier valve has the additional function of boosting pressure made available to the clutch during application of the clutch as the transmission is shifted to the fourth ratio. The provision of an independent exhaust circuit for the clutch and the modification of the pressure made available to the clutch during clutch application increases the rate of response of the clutch to a command by the electronic controller to engage the clutch. This also increases the rate of response of the clutch to a command to exhaust or release the clutch. The commands to effect engagement and release of the clutch and application and release of the brakes are developed by variable-force solenoids that are under the control of the microprocessor controller, which receives input control signals corresponding to powertrain operating variables.
REFERENCES:
patent: 5542889 (1996-08-01), Pierce et al.
patent: 5642283 (1997-06-01), Schulz et al.
patent: 5646842 (1997-07-01), Schulz et al.
patent: 5722519 (1998-03-01), Kirchhoffer et al.
patent: 5809442 (1998-09-01), Schulz et al.
patent: 5835875 (1998-11-01), Kirchhoffer et al.
patent: 6007445 (1999-12-01), Kirchhoffer
patent: 6122583 (2000-09-01), Kirchhoffer et al.
Crandall Scott Raymond
Haase Robert Clay
Kirchhoffer Johann
Cuchlinski Jr. William A.
Ford Global Technologies Inc.
Marc-Coleman Marthe
McKenzie Frank G.
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