192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2001-01-30
2003-02-04
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S10600R
Reexamination Certificate
active
06513636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a clutch construction in an automatic transmission for a vehicle.
2. Description of the Prior Art
In an automatic transmission mounted in an automobile etc, a planetary gear mechanism and engaging elements such as clutches are combined, and a plurality of gear positions are realized by a combination of engaging/disengaging of engaging elements.
Such an automatic transmission clutch construction is disclosed in for example Laid-open Japanese Patent publication number 6-185613.
In this clutch
80
, as shown in
FIG. 2
, a clutch drum
81
is a one-piece molding produced by press forming, and a spline
83
is formed on a tubular outer drum
82
thereof.
A plurality of friction plates
93
that respectively mesh with a spline
91
that is formed on a clutch hub
90
arranged facing the inside of the outer drum
82
and the aforesaid spline
83
are arranged alternately.
Within the clutch drum
81
, there is provided a piston
88
for applying pressure to the friction plates
93
. A pressure chamber
89
for driving this piston
88
is formed between this piston and the clutch drum
81
. In order to achieve an oil-tight stroke of the piston
88
, the outer circumferential surface of an inner tube
84
of the clutch drum
81
is made to serve as a sliding surface on the radially inwards side of the piston and the inner circumferential wall of a projection
86
formed on a vertical wall
85
is made to serve as a sliding surface on the radially outwards side of the piston.
However, the projection
86
forming the aforesaid piston sliding surface projects to the outside from the vertical wall
85
rather than to the interior of the clutch drum that accommodates the friction plates
93
and the clutch hub
90
. Furthermore, since the entire clutch drum
81
is constituted as a one-piece press molding, radiussing (R) is necessarily required at the corner portion in the cross-section, so the length dimension S of the projection
86
must take into account this radiussing in order to ensure the prescribed piston stroke.
Therefore the overall length of clutch drum
81
in the axial direction has to be large.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a clutch construction for an automatic transmission wherein the surroundings of the piston of clutch drum are made compact, enabling the axial length to be shortened.
To this end, the clutch construction according to the present invention comprises:
a clutch drum composed of an inner drum comprising a hub part, disc part and outer tube, and an outer drum having a drum and a vertical wall joined to the radially outside of the inner drum; a clutch hub arranged facing the outer drum within the clutch drum; a plurality of friction plates that alternately engage with the outer drum and the clutch hub; and a piston for applying pressure to the friction plates; wherein said inner drum constitutes a cylinder that accommodates the piston and the outer circumferential surface of the hub part and inner circumferential surface of the outer tube form sliding surfaces for the piston.
Since the outer tube of the inner drum is formed in a straight line in the axial direction as far as its tip, its inner circumferential surface as far as its tip can be utilized as a piston sliding surface of sufficient length even though the outer tube is short. In this way, the benefit is achieved that the necessary sliding surface length can be ensured even though the length of the clutch drum in the axial direction is shortened.
By providing the inner drum with a step at the corner from the disc part to the outer tube, the vertical wall of the outer drum being butt welded to this step, joining of the inner drum and outer drum can be achieved with high precision in the axial direction and radial direction.
Furthermore, by arranging the friction plates outside of the outer tube and the piston having an extension that extends outwards beyond the outer tube and comprising a portion that applies pressure to the friction plates at its radially outer end, this extension being offset towards the vertical wall of the outer drum after crossing the tip of the outer tube, the length of the clutch as a whole in the axial direction can be further shortened whilst guaranteeing a sufficient stroke gap with respect to the clutch hub.
A centrifugal canceling piston may be further provided on the outer circumferential surface of the hub part of the inner drum, this centrifugal canceling piston having an external diameter corresponding to the inner circumferential surface of the outer tube. The pressure-receiving area of each piston can thereby be equalized simply by altering the diameter of the outer tube; thus piston control with excellent balance can be obtained.
REFERENCES:
patent: 5172799 (1992-12-01), Iijima et al.
patent: 5755314 (1998-05-01), Kanda et al.
patent: 5992597 (1999-11-01), Nagai et al.
patent: 6039160 (2000-03-01), Joppeck
Han Ki Jung
Park Heonil
Jatco Transtechnology Ltd.
Rodriguez Saul
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