192 clutches and power-stop control – Clutches – Operators
Patent
1988-09-02
1990-08-28
Reese, Randolph A.
192 clutches and power-stop control
Clutches
Operators
192 52, 251206, F16D 2500
Patent
active
049517953
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a modulation valve device associated to a hydraulic clutch systems in industrial vehicles and others, and more particularly, to a modulation valve associated to clutch systems including various clutches for various speed ranges of the vehicles, so as to smoothly increase a hydraulic pressure to the clutch after the speed range is switched from a certain range to another range.
2. Description of the Prior Art
Generally, such a modulation valve comprises an accumulator and an orifice. The orifice is disposed in an inlet oil passage between an operation chamber of the modulation valve and a hydraulic source. When the selector valve is switched to a clutch-engaging position, the orifice restricts the flow of the operation oil into the operation chamber to prevent rapid increase of the pressure in the clutch.
It is desirable to change the control characteristics for increasing the hydraulic pressure in accordance with the selected speed range. More particularly, when the first speed range clutch is engaged, it is desirable to slowly increase the hydraulic pressure to surely prevent the shock during the engaging operation. When a high speed range (e.g., 3rd range) clutch is engaged, it is desirable to relatively rapidly increase the pressure so as to prevent a harmful slip of the clutch and a time delay before the complete engagement of the clutch.
However, the conventional structure includes only one orifice, which acts regardless of the selected range or position, so that the pressure characteristics are not changed.
Therefore, it is impossible in the conventional structures to set the pressure control characteristics suitable to all of the speed ranges. For example, if the orifice is designed to obtain the pressure control characteristics suitable to the first speed range, it is impossible to obtain the characteristics suitable to the second and third speed ranges.
Accordingly, it is an object of the present invention to provide a modulation valve device, overcoming the abovenoted disadvantages, which includes a variable orifice mechanism for selectively setting the characteristics of the orifice in accordance with the selected speed range.
SUMMARY OF THE INVENTION
According to the invention, a modulation valve device comprises an inlet passage adapted to be connected to a hydraulic pressure source; an outlet passage adapted to be selectively connected to one of a plurality of hydraulic clutches through a selector valve; an operation chamber to which the inlet and outlet passages connect; a plunger facing the operation chamber and adapted to be moved in accordance with a pressure in the operation chamber; an accumulator controllably connected to the outlet passage through a passage means of which opening degree is controlled by the plunger; a variable orifice mechanism associated with the inlet passage and including a plurality of orifices which have different flow resistances and are adapted to align a part of the inlet passage, respectively; and a control mechanism for selecting the orifice aligning a part of the inlet passage among a plurality of the orifices in accordance with the hydraulic clutch selected by the selector valve.
In the embodiment of the invention, the variable orifice mechanism includes a plunger which is movable transversely to the inlet passage and is provided with a plurality of orifices. The control mechanism includes a control chamber for hydraulically moving the plunger of the variable orifice mechanism and a connecting passage connecting at least one of the passages between the selector valve and the hydraulic clutches to the control chamber.
According to the structures described above, when the selector valve is switched to an engaging position of a certain clutch, the orifice corresponding to the selected clutch aligns with the inlet passage to restrict the inflow of the oil into the operation chamber, so that the pressure control characteristics are set appropriate to the selected clutch t
REFERENCES:
patent: 4422536 (1983-12-01), Shatuck
patent: 4560044 (1985-12-01), Nagata
patent: 4653533 (1987-03-01), Tanigawa et al.
DeLiguori Franco S.
Kabushiki Kaisha Daikin Seisakusho
Reese Randolph A.
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