Machine element or mechanism – Gearing – With fluid drive
Patent
1996-09-26
1998-09-22
Marmor, Charles A.
Machine element or mechanism
Gearing
With fluid drive
475 78, 477 69, F16H 4704
Patent
active
058098461
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of power transmission in a mechanical/hydraulic type transmission system, and more particularly to a method of power transmission in a mechanical/hydraulic type transmission system which is suitable for use as a transmission for self-propelled vehicles, e.g., construction machinery such as wheel type hydraulic excavators, rough terrain cranes, agricultural vehicles, automobiles, etc.
BACKGROUND ART
Heretofore, a mechanical/hydraulic type transmission system comprised a hydraulic power transmitting means for transmitting a mechanical power Pm, which had been converted from a hydraulic power Ph by a hydraulic motor, to the outside by the engagement of a clutch A, and a mechanical power transmitting means for transmitting a mechanical power Po to the outside by the engagement of a clutch B.
Because such a mechanical/hydraulic type transmission system can control the hydraulic power transmitting means and the mechanical power transmitting means separately from each other, the applicant has proposed to employ the system as a transmission for self-propelled vehicles, e.g., construction machinery such as wheel type hydraulic excavators, rough terrain cranes, agricultural vehicles, automobiles, etc. (see Japanese Unexamined Patent Publication No. 3-56754, for example).
When used as a transmission, the mechanical/hydraulic type transmission system provides the advantage that mechanical power transmission with a high power transmitting efficiency can be employed during running at high speeds and hydraulic power transmission with a high shift efficiency between forward and reverse gears and a capability of continuously variable speed change can be employed during running at low speeds.
A changeover between hydraulic power transmission and mechanical power transmission in the mechanical/hydraulic type transmission system is effected by releasing and engaging the clutches A and B simultaneously or alternately, because the hydraulic power transmitting means and the mechanical power transmitting means can be controlled separately from each other. However, if the clutches A and B are simply controlled to release and engage, a changeover shock (a shock upon releasing or engaging of the clutches) would be caused, and the clutches would generate excessive heat concomitantly, resulting in shorter machine life, and making an operator feel more unpleasant.
SUMMARY OF THE INVENTION
In view of the above-stated problem in the prior art, an object of the present invention is to provide a method of power transmission in a mechanical/hydraulic type transmission system, by which a changeover is smoothly effected between hydraulic power transmission and mechanical power transmission in the mechanical/hydraulic type transmission system, and hence which can reduce a changeover shock and the heat generation in the clutches, prolong machine life, and make an operator feel less unpleasant.
To achieve the above object, the present invention is constituted by a method of power transmission in a mechanical/hydraulic type transmission system comprising a hydraulic power transmitting means for transmitting a hydraulic power Ph by a hydraulic motor, to the outside by the engagement of a clutch A, and a mechanical power transmitting means for transmitting a mechanical power Po to the outside by the engagement of a clutch B, the clutches A and B being released and engaged simultaneously or alternately to effect a changeover from hydraulic power transmission to mechanical power transmission or from mechanical power transmission to hydraulic power transmission.
A first feature of the invention is that, upon a changeover from hydraulic power transmission to mechanical power transmission, the releasing of the clutch A is performed after the engagement of the clutch B is started and before the engagement of the clutch B is completed.
A second feature of the invention is that, upon a changeover from mechanical power transmission to hydraulic power transmission, the releasing of the clutch B
REFERENCES:
patent: 3442153 (1969-05-01), Ross
patent: 4790418 (1988-12-01), Brown et al.
patent: 4983149 (1991-01-01), Kita
patent: 5186692 (1993-02-01), Gleasman et al.
patent: 5683328 (1997-11-01), de Schepper et al.
Kanayama Noboru
Ohkura Yasunori
Estremsky Sherry Lyon
Komatsu Ltd.
Marmor Charles A.
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