Apparatus for controlling continuously variable transmission whe

Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position

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Details

3644241, B60K 4118, B60K 4112

Patent

active

046228659

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION



Field of the Art

This invention relates to an apparatus for controlling a continuously variable transmission (hereinafter called "CVT") used for a power transmission system of a vehicle and particularly to an apparatus for controlling same in acceleration.


BACKGROUND OF THE ART

A CVT is to control continously speed ratio e (=output side rotational speed Nout/input side rotational speed Nin) to be used for a vehicle as a power transmission system having excellent specific fuel consumption. In the CVT, a desired engine speed No is set as a function of running parameter of an engine such as intake throttle position .theta., vehicle speed V or the like and the CVT is controlled such that an actual engine speed Ne becomes the desired engine speed No. However, to provide drive feeling and drivability corresponding to the excellent specific fuel consumption and vehicle speed, the desired engine speed was set to a low value in low vehicle speed according to Pat. No. Sho-58-17551 applied previously by this applicant. Thus, even if a driver tries to accelerate a vehicle from a low vehicle speed in climbing a extremely steep slope by pedalling an accelerator pedal, the engine speed Ne is just slightly increased and engine output is not so much increased that unsatisfactory acceleration is disadvantageously provided.


DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an apparatus for controlling a CVT which ensures necessary engine output to provide satisfactory acceleration even in the acceleration from low vehicle speed.
According to the present invention to achieve this object, in the apparatus which sets a desired engine speed No as a function of running parameter and controls the CVT for a vehicle such that an actual engine speed Ne becomes the desired engine speed No, a speed ratio e of the CVT is reduced when the acceleration of the vehicle is required or demanded and the increase of a vehicle speed V is small.
Thus, in the acceleration from low vehicle speed in climbing a steep slope or the like, the speed ratio e is reduced if the acceleration of the vehicle is insufficient, and drive torque is increased as the engine output is increased so that the vehicle is to be rapidly accelerated.
Preferably, the desired engine speed No is increased to reduce the speed ratio e.
Further preferably, the desired engine speed No is increased by a predetermined amount, for example, in a predetermined interval of time until the vehicle speed V is highly increased, i.e. until the sufficient acceleration of the vehicle is obtained. Whether or not the acceleration is required is to be detected by comparing intake throttle position .theta. or its change with the passage of time with predetermined values .theta.1, .DELTA..theta.1.
For running parameters to set the desired engine speed No is to be selected the throttle position .theta. or intake pipe negative pressure P, vehicle speed V or the like.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a whole CVT to which the present invention is applied;
FIG. 2 is a block diagram showing an electronic control apparatus;
FIG. 3 is a graph showing a desired engine speed;
FIGS. 4 and 5 are flow charts showing control routine of the CVT; and
FIG. 6 is a functional block diagram according to the present invention.


THE MOST PREFERABLE EMBODIMENT FOR EMBODYING THE PRESENT INVENTION

Hereinafter will be detailed the present invention will reference to the drawings.
In FIG. 1, a crankshaft 2 of an engine 1 is connected to an input shaft 5 of a CVT 4 through a clutch 3. A pair of input side disks 6a,6b are provided opposed to each other, one input side disk 6a being provided on the input shaft 5 relatively axially slidably and the other input side disk 6b being fixedly secured to the input shaft 5. Also, a pair of output side disks 7a,7b are provided opposed to each other, one output side disk 7a being secured fixedly to an output shaft 8 and the other output side disk 7b being provided on the output shaft 8 axially movabl

REFERENCES:
patent: 3684066 (1972-08-01), Kubo et al.
patent: 3942393 (1976-03-01), Forster et al.
patent: 4200007 (1980-04-01), Espenschied et al.
patent: 4291594 (1981-09-01), Baudoin
patent: 4338666 (1982-07-01), Suzuki et al.
patent: 4471437 (1984-09-01), Yoshino et al.
patent: 4515040 (1985-05-01), Takeuchi et al.
patent: 4543855 (1985-10-01), Oetting et al.

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