US 5,045,035 AGranted

High-efficiency powertrain

OwnerDavid P. Ganounginventor

Life of this patent

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Abstract

A powertrain for passenger cars includes a high specific output engine coupled to an automatic transmission which is expanded from four to five forward speed ratios by a novel two-speed torque converter assembly within the transmission. Both of hydrodynamic action and an integral planetary gearset contribute to torque multiplication provided by the high-stall-speed torque converter when it is in its lower speed ratio, and engagement of a lockup clutch simultaneously deactivates both sources of torque multiplication to thereby establish a 100% efficient one-to-one speed ratio across the converter. Also included in the powertrain in a control system which secures high transmission efficiency early during vehicle acceleration by employing lockup of the torque converter as the first of the four upshifts for the five-speed transmission. Another control system utilizes a drive-by-wire type of engine throttle valve to implement an aggressive gearshift schedule and to limit engine intake air flow under stall conditions of the torque converter. These powertrain features exploit the fuel economy potential of modern high specific output engines and more effectively manage the characteristically peaky torque curve of such engines.

Claims20

Dependent claims

Power transmission apparatus for expanding the speed and torque ranges of the mechanical power produced by an internal combustion engine, the apparatus comprising:

a powershift geartrain having an upshift sequence which includes all forward speed ratios available in upshifting sequence for powershift operation of said powershift geartrain, at least three forward speed ratios being in said upshift sequence and said upshift sequence having an upshift which is executed first and with which a first numerical gear ratio gap is associated,
two-speed means which is coupled to deliver power from the engine to said powershift geartrain and which comprises (1) a hydrodynamic powerpath which delivers power from the engine to said powershift geartrain through a hydrodynamic device within said hydrodynamic powerpath and selected from fluid couplings and torque converters and (2) a lockup powerpath which delivers power from the engine to said powershift geartrain and in so doing bypasses said hydrodynamic device;
said hydrodynamic powerpath having associated therewith a low speed ratio measured between the engine and said powershift geartrain and calculated using an assumption of a one-to-one speed ratio across said hydrodynamic device, said lockup powerpath having a high speed ratio also measured between the engine and said powershift geartrain, said high speed ratio being in the upshift direction from said low speed ratio and a lockup ratio gap being that numerical ratio gap which separates said high and said low speed ratios,
and shift control means normally operative to initiate and proceed to completion of said upshift sequence in said powershift geartrain only when said lockup powerpath is being used to the exclusion of said hydrodynamic powerpath for delivering power from the engine to said powershift geartrain,
whereby hydrodynamic losses are eliminated early during acceleration of a load driven by the engine through the power transmission device.

2 more elements

Power transmission apparatus for expanding the speed and torque ranges of the mechanical power produced by an internal combustion engine, the apparatus comprising:

a hydrodynamic device selected from fluid couplings and torque converters, said hydrodynamic device having a power input element and a power output element,
planetary gearing comprising a sun gear, a ring gear and a planet carrier assembly having at least one planet gear in meshing engagement with teeth on said sun gear and with teeth on said ring gear, said ring gear being coupled to receive engine power from said output element of said hydrodynamic device and said planet carrier being adapted to deliver engine power from said planetary gearing;
and elements comprising said ring gear, said sun gear, said planet carrier assembly, said hydrodynamic input element and said hydrodynamic output element all sharing a common axis of rotation and all sharing space in a common rotating assembly,
brake means operative to automatically prevent rotation of said sun gear in a direction opposite to forward rotation of the engine, said brake means consisting of an overrunning type of device exemplified by sprag and roller clutches,
and a lockup clutch for selectively coupling said planet carrier assembly to said power input element of said hydrodynamic device to thereby bypass engine power around said hydrodynamic device,
whereby engagement of said lockup clutch upshifts the transmission apparatus and at the same time locks up said hydrodynamic device to thereby substantially eliminate hydrodynamic losses.

3 more elements

A two-speed hydrodynamic device for replacing a conventional single-speed torque converter or fluid coupling assembly in a multi-speed transmission to thereby provide at least one extra forward speed ratio for the transmission, the two-speed device comprising:

a hydrodynamic impeller for imparting energy to a fluid, said impeller being employed to receive input power delivered to the transmission,
a hydrodynamic turbine or runner for extracting said energy from said fluid,
planetary gearing comprising a sun gear, a ring gear and a planet carrier assembly having at least one planet gear in meshing engagement with teeth on said sun gear and with teeth on said ring gear, said ring gear being coupled to receive said input power from said hydrodynamic turbine or runner, said planet carrier being employed to deliver power from the two-speed device to remaining components of the transmission;
and said hydrodynamic impeller, said hydrodynamic turbine or runner, said sun gear, said ring gear and said planet carrier assembly all sharing a common axis of rotation and all sharing space in a common rotating assembly,
brake means for automatically engaging to prevent rotation of said sun gear in a direction opposite to forward rotation of said hydrodynamic turbine or runner, said brake means consisting of an overrunning type of device exemplified by roller and sprag clutches,
and a lockup clutch for selectively coupling said planet carrier assembly to said hydrodynamic impeller to thereby substantially eliminate hydrodynamic losses associated with said imparting and said extracting of energy from said fluid,
whereby engagement of said lockup clutch executes an upshift of the transmission and at the same time eliminates said hydrodynamic losses.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/516,433Filed 30 Apr 1990 · continuation in part
Priority: 19 Jan 1988
Granted: 3 Sep 1991
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

F16H 61/0204
The signals being electric: for gearshift control, e.g. control functions for performing shifting or generation of shift signal
F16H 47/06
Combinations of mechanical gearing with fluid clutches or fluid gearing: the fluid gearing being of the hydrokinetic type
F16H 61/143
Control of torque converter lock-up clutches: using electric control means
F16H 2045/0268
With damping means: the damper comprising a gearing