Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1989-07-26
1991-03-05
Diehl, Dwight
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74877, B60K 4100
Patent
active
049968939
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a speed change control device in an automatic transmission for an automobile.
BACKGROUND ART
A speed change control device in an automatic transmission is composed for example of a microcomputer etc. and a correlation between an accelerator opening and vehicle speed by which a shifting of each speed stage is commenced in each range is stored as a shift map in a storage means composed of a memory etc. In a shift map of a conventional speed change control device, a shift point has moved toward a high speed side with an increase in an accelerator opening as shown by FIG. 5. Consequently, as indicated by arrows A and B in FIG. 5, an automatic transmission has carried out a shift-up operation when an accelerator pedal has been released during running under a state of a large accelerator opening, and the automatic transmission has carried out a shift-down operation when the accelerator pedal has been fully trod down from the foregoing state. In FIG. 5, an axis of abscissa denotes the vehicle speed and an axis of ordinate denotes the accelerator opening, a solid line C denotes a shift-up timing from 1st speed to 2nd speed, a solid line D denotes a shift-up timing from 2nd speed to 3rd speed, a broken line E denotes a shift-down timing from 2nd speed to 1st speed, and a broken line F denotes a shift-down timing from 3rd speed to 2nd speed, respectively.
A vehicle, such as a commercial car powered by a small engine torque relatively to its weight, has frequently subjected to a driving condition with an accelerator pedal opened to a large extent in a driving along a mountain road or in a driving with a heavy weight loaded, so that a vehicle equipped with a conventional speed change control device frequently encounters a so-called hunting state wherein shift-up and shift-down occur very often to cause a bad drive feeling in a driving along a mountain path such as a meandering road on which the accelerator pedal has to be opened and closed frequently. Further, when driving a road with frequent uphill and downhill, an engine braking effect has become worse due to the shift-up so that a driver has been forced to operate frequent braking actions.
DISCLOSURE OF THE INVENTION
In order to solve the foregoing problem, this invention provides a speed change control device in an automatic transmission for an automobile equipped with a storage means storing a correlation between an accelerator opening and a vehicle speed by which a shifting in each speed stage is commenced, characterized by that there provided an accelerator opening rate-of-change computing means computing a rate-of-change of an accelerator opening on the basis of a detection signal from an accelerator opening detector detecting the accelerator opening and a shift-up prohibiting means prohibiting a shift-up operation when the accelerator opening rate-of-change computed by the accelerator opening rate-of-change computing means is more than or equal to a specified value, and at the same time the correlation between the accelerator opening and the vehicle speed in storage means is preset in such a manner that a shift point is deviated so as to execute the shift-up operation at a constant high vehicle speed when an accelerator opening is smaller than or equal to a specified value.
According to the above-mentioned structure, the accelerator opening rate-of-change computing means computes the rate-of-change of the accelerator opening on the basis of the detection signal from the accelerator opening detector which detects the accelerator opening. And, the shift-up prohibiting means prohibits the shift-up operation when the accelerator opening rate-of-change computed by the accelerator opening rate-of-change computing means is more than or equal to a prescribed value. Consequently, the shift-up operation is not executed in case when the accelerator is opened and closed at a speed larger than a prescribed value, so that the repeated frequent shift-up/shift-down operations become unnecessary to improve the drive feeling. F
REFERENCES:
patent: 4643048 (1987-02-01), Hattori et al.
patent: 4843551 (1989-06-01), Milunas
patent: 4848529 (1989-07-01), Kurihara et al.
patent: 4889015 (1989-12-01), Kondo
patent: 4896569 (1990-01-01), Ito et al.
patent: 4913006 (1990-04-01), Tsuyama et al.
Nakamura Katsuma
Shiba Hirofumi
Diehl Dwight
Kabushiki Kaisha Daikin Seisakusho
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