US4866624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for controlling vehicle four wheel drive front/rear coupling device according to rotational speeds of front and rear vehicle wheels and method of operation thereof
Assignee: Toyota Motor Corp
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Filing: 1987-06-08
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Granted: 1989-09-12
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Expires: 2007-06-08
Abstract
Abstract In a four wheel drive vehicle, a four wheel drive device receives rotational power from an engine and provides it to the combination of the front wheels of the vehicle and also to the combination of the rear wheels of the vehicle. A device is provided for selectively coupling the rotation of the combination of the front vehicle wheels and the rotation of the combination of the rear vehicle wheels. A control device is provided for this front/rear coupling device, and includes: (a) a means for detecting the rotational speed of the combination of the front wheels of the vehicle; (b) a means for detecting the rotational speed of the combination of the rear wheels of the vehicle; and: (c) a means for controlling the front/rear coupling device, so that its operation is substantially not restricted when the discrepancy between the rotational speed of the combination of the front wheels of the vehicle and the rotational speed of the combination of the rear wheels of the vehicle is not greater than a certain threshold value; while, when the discrepancy between the rotational speed of the combination of the front wheels of the vehicle and the rotational speed of the combination of the rear wheels of the vehicle is greater than the certain threshold value, coupling between the rotation of the combination of the front vehicle wheels and the rotation of the combination of the rear vehicle wheels is substantially prohibited. The method of operation of this device is also disclosed.
Inventors
- 👤 Seiichi Nishikawa
- 👤 Tadashi Saitou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:08
CPC Classifications
B; B60; B60K; B60K23/00; B60K23/08; B60K23/0808
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
271 words
For a four wheel drive vehicle with two front wheels, two rear wheels, a four wheel drive device, and an engine, rotational power from said engine being provided via said four wheel drive device to the combination of the front wheels of said vehicle and also to the combination of the rear wheels of said vehicle, and further comprising a front/rear coupling device fitted to said four wheel drive device for selectively coupling the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels: a device for controlling said front/rear coupling device, comprising: (a) a means for detecting the rotational speed of said combination of the front wheels of said vehicle; (b) a means for detecting the rotational speed of said combination of the rear wheels of said vehicle; and: (c) a means for controlling said front/rear coupling device, so that: said operation of said front/rear coupling device is substantially not restricted when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is not greater than a certain threshold value; and, when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is greater than said certain threshold value, coupling between the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels by said front/rear coupling device is substantially prohibited.
Claim 2
Dependent Claim
271 words
For a four wheel drive vehicle with two front wheels, two rear wheels, a four wheel drive device, and an engine, rotational power from said engine being provided via said four wheel drive device to the combination of the front wheels of said vehicle and also to the combination of the rear wheels of said vehicle, and further comprising a front/rear coupling device fitted to said four wheel drive device for selectively coupling the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels: a device for controlling said front/rear coupling device, comprising: (a) a means for detecting the rotational speed of said combination of the front wheels of said vehicle; (b) a means for detecting the rotational speed of said combination of the rear wheels of said vehicle; and: (c) a means for controlling said front/rear coupling device, so that: said operation of said front/rear coupling device is substantially not restricted when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is not greater than a certain threshold value; and, when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is greater than said certain threshold value, coupling between the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels by said front/rear coupling device is substantially prohibited.
Claim 3
Dependent Claim
46 words
A front/rear coupling device control device according to claim 1, wherein said discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is a rotational speed difference.
Claim 4
Dependent Claim
46 words
A front/rear coupling device control device according to claim 1, wherein said discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is a rotational speed ratio.
Claim 5
Dependent Claim
66 words
A front/rear coupling device control device according to claim 1, further comprising a means for detecting the value of torque which is being inputted to said four wheel drive device, wherein said certain threshold value of discrepancy between the rotational speed of said front wheels of said vehicle is smaller when the value of torque which is being inputted to said four wheel drive device increases.
Claim 6
Dependent Claim
77 words
A front/rear coupling device control device according to claim 1, said vehicle further comprising a speed change device provided in the power train between said engine and said four wheel drive device, wherein said certain threshold value of discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the speed stage to which said speed change device is set is lower.
Claim 7
Dependent Claim
51 words
A front/rear coupling device control device according to claim 1, wherein said certain threshold value of discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the value of output torque of said engine increases.
Claim 8
Dependent Claim
77 words
A front/rear coupling device control device according to claim 6, said vehicle further comprising a speed change device provided in the power train between said engine and said four wheel drive device, wherein said certain threshold value of discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the speed stage to which said speed change device is set is lower.
Claim 9
Dependent Claim
265 words
For a four wheel drive vehicle with two front wheels, two rear wheels, a four wheel drive device, and an engine, rotational power from said engine being provided via said four wheel drive device to the combination of the front wheels of said vehicle and also to the combination of the rear wheels of said vehicle, and further comprising a front/rear coupling device fitted to said four wheel drive device for selectively coupling the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels: a method for controlling said front/rear coupling device, wherein: (a) the rotational speed of said combination of the front wheels of said vehicle is detected; (b) the rotational speed of said combination of the rear wheels of said vehicle is detected; and: (c) said front/rear coupling device is controlled, so that: said operation of said front/rear coupling device is substantially not restricted when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is not greater than a certain threshold value; and, when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is greater than said certain threshold value, coupling between the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels by said front/rear coupling device is substantially prohibited.
Claim 10
Dependent Claim
265 words
For a four wheel drive vehicle with two front wheels, two rear wheels, a four wheel drive device, and an engine, rotational power from said engine being provided via said four wheel drive device to the combination of the front wheels of said vehicle and also to the combination of the rear wheels of said vehicle, and further comprising a front/rear coupling device fitted to said four wheel drive device for selectively coupling the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels: a method for controlling said front/rear coupling device, wherein: (a) the rotational speed of said combination of the front wheels of said vehicle is detected; (b) the rotational speed of said combination of the rear wheels of said vehicle is detected; and: (c) said front/rear coupling device is controlled, so that: said operation of said front/rear coupling device is substantially not restricted when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is not greater than a certain threshold value; and, when the discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is greater than said certain threshold value, coupling between the rotation of said combination of said front vehicle wheels and the rotation of said combination of said rear vehicle wheels by said front/rear coupling device is substantially prohibited.
Claim 11
Dependent Claim
46 words
A front/rear coupling device control method according to claim 8, wherein said discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is a rotational speed difference.
Claim 12
Dependent Claim
46 words
A front/rear coupling device control method according to claim 8, wherein said discrepancy between the rotational speed of said combination of the front wheels of said vehicle and the rotational speed of said combination of the rear wheels of said vehicle is a rotational speed ratio.
Claim 13
Dependent Claim
76 words
A front/rear coupling device control method according to claim 8, wherein the value of torque which is being inputted to said four wheel drive device is detected, and wherein said certain threshold value of discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the value of the torque which is being inputted to said four wheel drive device increases.
Claim 14
Dependent Claim
66 words
A front/rear coupling device control method according to claim 8, said vehicle further comprising a speed change device provided in the power train between said engine and said four wheel drive device, wherein said certain threshold value of discrepancy between the rotational speed of said front wheels of said vehicle is smaller when the speed stage to which said speed change device is set is lower.
Claim 15
Dependent Claim
51 words
A front/rear coupling device control method according to claim 8, wherein said certain threshold value or discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the value of output torque of said engine increases.
Claim 16
Dependent Claim
77 words
A front/rear coupling device control method according to claim 13, said vehicle further comprising a speed change device provided in the power train between said engine and said four wheel drive device, wherein said certain threshold value of discrepancy between the rotational speed of said rear wheels of said vehicle and the rotational speed of said front wheels of said vehicle is smaller when the speed stage to which said speed change device is set is lower.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-11 | 1993-03-13 | 1993-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-11 | 1997-03-13 | 1997-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-11 | 2001-03-13 | 2001-09-12 | $7700.00 | Window Closed / Lapsed |