Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1988-12-07
1991-02-19
Diehl, Dwight
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74335, B60K 4106
Patent
active
049932853
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and an apparatus for controlling a speed changing unit mounted on a moving machine, a construction machine or the like and more particularly to a method and an apparatus for suppressing fluctuation in filling time when an amount of hydraulic oil delivered from a hydraulic pump is reduced at the time of starting of forward movement or the like.
BACKGROUND ART
A speed changing unit of the type including clutches at a first stage (on the auxiliary speed changing side) and clutches at a second stage (on the main speed changing unit side) as viewed from an input shaft thereof is adapted to select a certain speed stage using a proper combination of clutches on the auxiliary speed changing unit side and clutches on the main speed changing unit side.
Hitherto, a speed changing unit of the aforementioned type is so constructed that clutches on the auxiliary speed changing unit side and clutches on the main speed changing unit side are simultaneously brought in an engaged state by simultaneously feeding hydraulic oil to them when speed changing is effected. Namely, when such a conventional system as mentioned above is employed, hydraulic oil is simultaneously fed to two clutches at the time of speed changing.
Thus, the conventional system has a drawback that hydraulic pressure of hydraulic oil delivered from the hydraulic pump is lowered due to a shortage in amount of hydraulic oil delivered therefrom compared with a capacity of the respective clutches when an amount of hydraulic oil delivered therefrom is reduced at the time of starting of forward movement, speed changing under the influence of inertia or the like occasion. As shown in FIG. 10, the lowering of hydraulic pressure of hydraulic oil delivered from the hydraulic pump causes delayed filling time and fluctuation in filling time, resulting in a variety of malfunctions such as generation of shock due to speed changing or the like taking place when filling is terminated, for instance, in the course of gradual increase of hydraulic pressure for the clutches in a case where the latter are intended to be controlled with the same pattern of hydraulic pressure.
Hence, the present invention has been made with the foregoing background in mind and its object resides in providing a method and an apparatus for controlling a speed changing unit which assure that a malfunction attributable to lowering of hydraulic pressure of hydraulic oil delivered from a hydraulic pump when an amount of hydraulic oil delivered therefrom is reduced at the time of starting of forward movement or the like is obviated.
DISCLOSURE OF THE INVENTION
The present invention consists in that when an amount of hydraulic oil delivered from the hydraulic pump does not reach a predetermined value and clutches to be brought in an engaged state are both of those on the auxiliary speed changing unit side and those on the main speed changing unit side, pressure control values corresponding to these clutches are controlled by way of the following steps. changing unit side are actuated so as to allow pressurized hydraulic oil to be fed to them. clutches on the auxiliary speed changing unit side. filling time is terminated, the pressure control valves relating to the clutches on the auxiliary speed changing unit side are controlled to gradually increase clutch pressure exerted on the clutches and the pressure control valves relating to the clutches on the main speed changing unit side are actuated so as to allow pressurized hydraulic oil to be fed to the clutches. clutches on the main speed changing unit side and the pressure control valves relating to the clutches are controlled to increase clutch pressure on the main speed changing unit side from the time point of the above confirmation.
According to the present invention which is concerned with a speed changing unit constructed in the two-staged clutch structure including a main speed changing unit and an auxiliary speed changing unit, since when it is found that hydraulic oil delivered fr
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Asayama Yoshio
Okura Yasunori
Sato Takayuki
Tsubota Makio
Diehl Dwight
Kabushiki Kaisha Komatsu Seisakusho
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