Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2000-04-28
2001-12-25
Estremsky, Sherry (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
C137S625640, C192S083000
Reexamination Certificate
active
06332855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to controllers for automatic transmissions mounted on vehicles, and more particularly to improvements to such a controller which includes a split-type valve body in which a pressure adjusting valve and an electromagnetic valve are accommodated.
2. Background Art
One such conventional controller for an automatic transmission is disclosed, for example, in a published unexamined Japanese patent application 8-270779. In this controller for an automatic transmission, for example, a select lever and a manually operated valve are used to change an area of a spool valve on which a pressure of the hydraulic oil acts so as to correspond to an N- or P-range indicative of a non-travelling state or a D- or R-range indicative of a travelling state. Thus, for example in the non-travelling state, a load on the pump is reduced. A pressure control valve which controls the pressure of the hydraulic oil acting on frictionally engageable elements of the automatic transmission is composed of a pressure adjusting valve which adjusts an opening in the valve depending on a quantity of movement of its spool to change the pressure of the hydraulic oil, and an electromagnetic valve which outputs a pilot (output) pressure to the pressure adjusting valve such that the electromagnetic valve is generally duty-cycle controlled to adjust the fed hydraulic oil pressure. Both the valves are generally provided within a valve body provided in a lower portion of the automatic transmission.
Since a general valve body is required to contain a spool and other elements, it is often divided into an upper and a lower body half. In order to ensure the freedom of layout of elements of the valve, an accumulator which absorbs vibrations of the hydraulic oil pressure is provided between the spool valve and the electromagnetic valve with the electromagnetic valve, spool valve and accumulator being provided in the lower body half. In this case, it is found that when a hydraulic oil path is provided between the electromagnetic valve and the spool valve so as to extend through the upper half of the valve body to connect the two valves provided in the lower half of the valve body, the vibrations of the oil pressure are amplified and that response to the gear shift control is deteriorated.
The present invention has been made in view of those problems. It is therefore an object of the present invention to provide a controller for an automatic transmission capable of ensuring the freedom of layout of components thereof and avoiding amplification of vibrations of the oil pressure and a reduction in the response to the gear shift control.
SUMMARY OF THE INVENTION
In order to achieve the above object, the present invention provides a controller for an automatic transmission comprising: frictionally engagable elements to be engaged/disengaged depending on a pressure of a hydraulic oil applied to the frictionally engagable elements; a pressure adjusting valve for adjusting the pressure of the hydraulic oil to be applied to the frictionally engagable elements; an electromagnetic valve for providing an output pressure to control the pressure adjusting valve; and a control valve which accommodates the pressure adjusting valve and the electromagnetic valve, the control valve having at least an upper valve body half and a lower valve body half. An a hydraulic oil path extending between the pressure adjusting valve and the electromagnetic valve is formed between the upper and lower valve body halves in a zigzagging manner. An accumulator fluid communicating with the oil path is disposed on one of the upper and lower valve body halves and, an oil chamber of the accumulator which applies the oil pressure to a piston of the accumulator is communicated with a top of the oil path formed in the one of the valve body halves. And an air discharge path which functions as a discharge path of hydraulic oil is provided on an opposite side of the accumulator from the oil chamber such that when the oil pressure is applied to the oil path, possible air staying up within the oil path is discharged through the air discharge path to the outside.
The piston of the accumulator may be placed in direct contact with the cylinder of the accumulator provided in the one of the upper and lower valve body halves without an intervening sealing member.
In order achieve the above object, the present invention also provides a controller for an automatic transmission comprising: frictionally engagable elements to be engaged/disengaged depending on a pressure of a hydraulic oil applied to the frictionally engagable elements; a pressure adjusting valve for adjusting the pressure of the hydraulic oil to be applied to the frictionally engagable elements; an electromagnetic valve for providing an output pressure to control the pressure adjusting valve; and a control valve which accommodates the pressure adjusting valve and the electromagnetic valve, the control valve having at least an upper valve body half and a lower valve body half. An a hydraulic oil path extending between the pressure adjusting valve and the electromagnetic valve is formed between the upper and lower valve body halves in a zigzagging manner. The pressure adjusting valve is disposed in one of the upper and lower valve body halves. A part of the pressure adjusting valve is fluid communicated with a top of the oil path formed in the one of the valve body halves. And an air discharge path, which functions as a discharge path of hydraulic oil is provided on an opposite side of a spool of the pressure adjusting valve from its side to which the oil pressure is applied such that when the oil pressure is applied to the oil path, possible air staying up within the oil path is discharged through the air discharge path to the outside.
The controller may comprise a plug provided on an opposite side of the spool of the pressure adjusting valve from its side to which the oil pressure is applied, and a pin provided within the air discharge path so as to fix the plug.
REFERENCES:
patent: 4657041 (1987-04-01), Mitsui
patent: 5291745 (1994-03-01), Hanson
patent: 5562125 (1996-10-01), Bray
patent: 5829560 (1998-11-01), Mainquist et al.
patent: 5902204 (1999-05-01), Takagi
patent: 5913577 (1999-06-01), Arndt
patent: 6065487 (2000-05-01), Watson
patent: 6167901 (2001-01-01), Yoshinura
patent: 6263751 (2001-07-01), Arimoto
patent: 8-270779 (1996-10-01), None
Estremsky Sherry
Foley & Lardner
Jatco Transtechnology Ltd.
Pang Roger
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