Transmission for four-wheel drive vehicles
First Claim
1. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
- an input shaft driven by the engine about a first rotary axis;
a mainshaft supported for rotation about a second rotary axis;
a gear reduction unit including a sun gear rotatably supported on said mainshaft, a non-rotatable ring gear, and a planet carrier having pinion gears meshed with said ring gear and said sun gear;
constant-mesh gearsets supported between said input shaft and said mainshaft;
synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at speed ratios relative to said input shaft for establishing forward gears and a reverse gear;
a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis;
a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis;
an interaxle differential for permitting speed differentiation between said rear output shaft and said front output shaft, said interaxle differential including an input member driven by said mainshaft, a first output member fixed for rotation with said rear output shaft, and a second output member;
a range clutch operable in a first position to couple said input member of said interaxle differential to said mainshaft for establishing a direct speed ratio drive connection, and said range clutch is further operable in a second position to couple said sun gear to said mainshaft and said planet carrier to said input member of said interaxle differential for establishing a reduced speed ratio drive connection; and
a transfer mechanism connecting said front output shaft for common rotation with said second output member.
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Accused Products
Abstract
The transmission of the present invention includes a multi-speed geartrain comprised of an input shaft, a mainshaft, and a plurality of constant-mesh gearsets arranged for selectively coupling the mainshaft to the input shaft for driven rotation at various speed ratios. The mainshaft can be selectively coupled to the power transfer arrangement for establishing two alternative power transmission routes. In particular, the range shift mechanism is provided for establishing a high-range power transmission route and a low-range power transmission route from the mainshaft to a quill shaft which, in turn, drives the interaxle differential. The torque delivered by the quill shaft is split by the interaxle differential between the front and rear drivelines to establish the full-time four-wheel high-range and low-range drive modes. Optionally, the torque transfer apparatus can be provided for controlling speed differentiation across the interaxle differential or in place of the interaxle differential for on-demand four-wheel drive operation. The torque transfer apparatus can be a speed-sensitive device or an electronically-controlled transfer clutch.
24 Citations
17 Claims
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1. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine about a first rotary axis; a mainshaft supported for rotation about a second rotary axis; a gear reduction unit including a sun gear rotatably supported on said mainshaft, a non-rotatable ring gear, and a planet carrier having pinion gears meshed with said ring gear and said sun gear; constant-mesh gearsets supported between said input shaft and said mainshaft; synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at speed ratios relative to said input shaft for establishing forward gears and a reverse gear; a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis; a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis; an interaxle differential for permitting speed differentiation between said rear output shaft and said front output shaft, said interaxle differential including an input member driven by said mainshaft, a first output member fixed for rotation with said rear output shaft, and a second output member; a range clutch operable in a first position to couple said input member of said interaxle differential to said mainshaft for establishing a direct speed ratio drive connection, and said range clutch is further operable in a second position to couple said sun gear to said mainshaft and said planet carrier to said input member of said interaxle differential for establishing a reduced speed ratio drive connection; and a transfer mechanism connecting said front output shaft for common rotation with said second output member.
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2. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine about a first rotary axis; a mainshaft supported for rotation about a second rotary axis; constant-mesh gearsets supported between said input shaft and said mainshaft; synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at speed ratios relative to said input shaft for establishing forward gears and a reverse gear; a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis; a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis; an interaxle differential for permitting speed differentiation between said rear output shaft and said front output shaft, said interaxle differential including an input member driven by said mainshaft, a first output member fixed for rotation with said rear output shaft, and a second output member; a gear reduction unit including a sun gear fixed for rotation with said mainshaft, a ring gear, and a planet carrier fixed for rotation with said input member of said differential and having pinion gears meshed with said ring gear and said sun gear; a range clutch supported for rotation with said ring gear and which is operable in a first position to couple said ring gear to said input member of said interaxle differential for establishing a direct speed ratio drive connection, and said range clutch is operable in a second position for coupling said ring gear to a stationary member for establishing a reduced speed ratio drive connection; and a transfer mechanism connecting said front output shaft for common rotation with said second output member.
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3. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine about a first rotary axis; a mainshaft supported for rotation about a second rotary axis; constant-mesh gearsets supported between said input shaft and said mainshaft; synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at speed ratios relative to said input shaft for establishing forward gears and a reverse gear; a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis; a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis; an interaxle differential for permitting speed differentiation between said rear output shaft and said front output shaft, said interaxle differential including an input member driven by said mainshaft, a first output member fixed for rotation with said rear output shaft, and a second output member; a torque transfer apparatus for inhibiting speed differentiation across said interaxle differential in response to excessive speed differentials between said front and rear output shafts; and a transfer mechanism connecting said front output shaft for common rotation with said second output member. - View Dependent Claims (4)
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5. The transmission of claim wherein said torque transfer apparatus is a multi-plate transfer clutch operable for selectively limiting speed differentiation between said front and rear output shafts, and wherein said transmission further comprises:
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an actuator for varying the actuated condition of said transfer clutch between a non-actuated state whereat unrestricted speed differentiation between said front and rear output shafts is permitted and a fully-actuated state whereat such speed differentiation is inhibited; sensor means for detecting dynamic and operational characteristics of the vehicle and generating sensor input signals indicative thereof; and a controller for controlling actuation of said actuator in response to said sensor input signals.
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6. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine; a mainshaft; a plurality of constant-mesh gearsets supported between said input shaft and said mainshaft; a plurality of clutches for selectively engaging one of said gearsets for driving said mainshaft at a predetermined speed ratio relative to said input shaft so as to establish forward gears and a reverse gear; a gear reduction unit driven by said mainshaft at a reduced speed ratio relative thereto; an interaxle differential having an input and first and second outputs; a range clutch for selectively coupling said input of said interaxle differential to one of said mainshaft whereat a direct speed ratio drive connection is established and said gear reduction unit whereat said reduced speed ratio drive connection is established; a rear output shaft coupled to said first output of said interaxle differential and adapted for connection to the rear driveline; a front output shaft adapted for connection to the front driveline; a torque transfer apparatus for inhibiting speed differentiation across said interaxle differential in response to excessive speed differentials between said front and rear output shafts; and a transfer mechanism connecting said front output shaft to said second output of said interaxle differential. - View Dependent Claims (7, 8, 9, 10)
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11. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine about a first rotary axis; a mainshaft supported for rotation about a second rotary axis; constant-mesh gearsets supported between said input shaft and said mainshaft; synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at a predetermined speed ratio relative to said input shaft so as to establish a forward gear and a reverse gear; a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis; a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis; a gear reduction unit driven by said mainshaft at a reduced speed ratio relative thereto;
said gear reduction unit including a sun gear rotatably supported on said mainshaft, a non-rotatable ring gear, and a planet carrier having pinion gears meshed with said ring gear and said sun gear;a range clutch movable between a first position whereat it directly couples said rear output shaft to said mainshaft for establishing a direct speed ratio drive connection, and a second position whereat it couples said sun gear to said mainshaft and said planet carrier to said rear output shaft for establishing a reduced speed ratio drive connection; and a transfer clutch for transferring drive torque from said rear output shaft to said front output shaft in response to a predetermined slip therebetween.
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12. A transmission for a four-wheel drive vehicle having an engine and front and rear drivelines, said transmission comprising:
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an input shaft driven by the engine about a first rotary axis; a mainshaft supported for rotation about a second rotary axis; constant-mesh gearsets supported between said input shaft and said mainshaft; synchronizer clutches for selectively engaging said gearsets for driving said mainshaft at a predetermined speed ratio relative to said input shaft so as to establish a forward gear and a reverse gear; a rear output shaft adapted for connection to the rear driveline and which is commonly aligned with said mainshaft for rotation about said second rotary axis; a front output shaft adapted for connection to the front driveline and which is supported for rotation about a third rotary axis; a gear reduction unit driven by said mainshaft at a reduced speed ratio relative thereto; a range clutch for selectively coupling said rear output shaft to either of said mainshaft and said gear reduction unit; and a transfer clutch for transferring drive torque from said rear output shaft to said front output shaft in response to a predetermined slip therebetween. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification