Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Fluid pressure actuator for adjustment of member
Reexamination Certificate
2001-02-09
2003-05-13
Charles, Marcus (Department: 3681)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Fluid pressure actuator for adjustment of member
C474S018000
Reexamination Certificate
active
06561934
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an oil pressure controlling apparatus for continuously variable transmission (CVT).
As illustrate in
FIGS. 1A and 1B
, a CVT
500
is mainly provided with a primary shaft
520
and a secondary shaft
530
arranged in parallel, a primary pulley
550
and a secondary pulley
570
attached to the shafts
520
and
530
, respectively, and a drive belt
590
passed over the pulleys
550
and
570
.
The CVT
500
continuously varies the speed ratio of driving and driven elements over working range by varying an effective winding ratio of the drive belt
590
to the pulleys
550
and
570
.
The primary pulley
550
has a fixed pulley
550
a
that is driven via a torque converter and a forward/backward-switching mechanism, etc., and a slidable pulley
550
b
. The slidable pulley
550
b
is attached to the shaft of the fixed pulley
550
a
via ball splines
550
c
for varying a pulley-groove width so that the slidable pulley
550
b
is slidable in the direction of the shaft and rotates with the fixed pulley in a uniform motion with respect to each other. A transmission oil-pressure cylinder
560
consists of a cylinder
560
a
fixed at the back of the slidable pulley
550
b
and a plunger
560
b
attached to the shaft of the fixed pulley
550
a.
Likewise, the secondary pulley
570
has a fixed pulley
570
a
connected to drive wheels via a reduction mechanism, etc. A slidable pulley
570
b
is attached to the shaft of the fixed pulley
570
a
via ball splines
570
c
so that the slidable pulley
570
b
is slidable in the direction of the shaft and rotates with the fixed pulley in a uniform motion with respect to each other. A transmission oil-pressure cylinder
580
consists of a cylinder
580
a
fixed to the back of the slidable pulley
570
b
and a plunger
580
b
attached to the shaft of the fixed pulley
570
a.
Oil pressure applied by an oil pump to the oil pressure cylinders
560
and
580
provided at the primary pulley
550
and the secondary pulley
570
, respectively, are controlled for power transfer and transmission control between the drive belt
590
and the primary and the secondary pulleys
550
and
570
.
The primary and the secondary pulleys
550
and
570
are rotating at a predetermined rotational ratio while the CVT
500
is operating. The rotation of pulleys causes generation of centrifugal oil pressure to the oil pressure cylinders
560
and
580
.
The centrifugal oil pressure generated to the oil pressure cylinder
560
provided in the primary pulley
550
is applied thereto in a up-shift direction to force the pulley-groove width to be narrow, or to overdrive (OD) in transmission.
Contrary to this, the centrifugal oil pressure generated to the oil pressure cylinder
580
provided in the secondary pulley
570
is applied thereto in a shift-down direction to force the pulley-groove width to be narrow, or to LOW in transmission.
A balance oil chamber
610
is formed on the back of the plunger
560
b
as a part of the oil pressure cylinder
560
for the primary pulley
550
. The balance oil chamber
610
is filled with oil to generate centrifugal oil pressure that cancels force applied in the OD direction due to generation of centrifugal oil pressure in the oil pressure cylinder
560
.
Moreover, a balance oil chamber
620
is formed on the back of the plunger
580
b
by means of a balance oil chamber cylinder
580
d
, one end of which is connected to a tip of a cylinder portion
580
a
that is a part of the oil pressure cylinder
580
and the other end is set as slidable along the shaft of a fixed pulley
570
a
. The balance oil chamber
620
is filled with oil to generate centrifugal oil pressure that cancels force applied in the LOW direction due to generation of centrifugal oil pressure in the oil pressure cylinder
580
.
A lubricant is always supplied by an oil pump (not shown) into the balance oil chamber
620
formed in the secondary pulley
570
. Shift-down from OD to LOW in transmission speed of the CVT
500
displaces the slidable pulley
570
b
to left in
FIG. 1B
(in the direction of the fixed pulley
750
a
) due to oil pressure applied to the oil cylinder
580
of the secondary pulley
570
. This results in contraction of the volume of the balance oil chamber
620
so that the lubricant in the chamber
620
is extruded through a gap
630
formed between the shaft of the fixed pulley
570
a
and the end of the balance oil cylinder
58
d.
Oil pressure used for control and lubrication in the CVT
500
is obtained by the oil pump driven by an engine (not shown). Change in transmission speed by varying the groove-width of the primary and the secondary pulleys
550
and
570
requires enough oil in the oil pump to follow change in volume of the oil cylinders
560
and
580
for prevention of a slip of the drive belt
590
which would otherwise happen due to decrease in clamping power of the belt
590
. The oil amount in the oil pump is set for attaining oil flow required for lubrication to forward/backward-switching, etc.
As discussed, energy for driving the oil pump is increased for supplying enough oil to cover energy loss caused by sliding resistance generated in each component. Such energy for the oil pump is also increased to supply oil to components at a pulley-transmission control pressure even though the components operate at a pressure lower than the pulley-transmission control pressure.
The CVT
500
smoothly performs transmission speed control by restricting unnecessary force which would otherwise be generated due to generation of centrifugal oil pressure in the oil pressure cylinders
560
and
580
, with the structure in that the balance oil chamber
610
is formed on the back of the plunger
560
b
as a part of the oil pressure cylinder
560
of the primary pulley
550
and the balance oil chamber
620
is formed on the back of the plunger
580
b
as a part of the balance oil chamber cylinder
580
d
of the secondary pulley
570
.
The balance oil chamber
620
formed in the secondary pulley
570
is, however, always filled with the lubricant supplied by the oil pump, which causes increase in amount of the lubricant required for CVT operation, thus the oil pump becoming bulk to increase mechanical loss and fuel consumption.
SUMMARY OF THE INVENTION
A purpose of the present invention is to provide an oil pressure control apparatus for CVTs, that decreases consumption of a lubricant supplied by a oil pump.
Another purpose of the present invention is to provide an oil pressure control apparatus for CVTs, that decreases consumption of a lubricant for compactness of an oil pump with decrease in mechanical loss and fuel consumption.
The present invention provides an oil-pressure control apparatus for a continuously variable transmission having a primary pulley and a secondary pulley, a belt being passed around the primary and the secondary pulleys, the apparatus including: a primary cylinder provided for the primary pulley, having an oil chamber for applying an oil pressure to the primary pulley and a balance oil chamber for applying a centrifugal oil pressure to the primary pulley in a direction which is reverse of a centrifugal oil pressure generated in the oil chamber; a primary valve for adjusting a primary pressure to be applied to the oil chamber based on a line pressure applied by an oil pump; and a balance oil line that connects a drain port of the primary valve and the balance oil chamber, oil being supplied from the primary valve to the balance oil chamber through the balance oil line.
Moreover, the present invention provides an oil-pressure control apparatus for a continuously variable transmission having a primary pulley and a secondary pulley, a belt being passed around the primary and the secondary pulleys, the apparatus including: a primary cylinder provided for the primary pulley, having a primary chamber for applying an oil pressure to the primary pulley and a primary balance oil chamber for applying a centrifugal oil pressure to the primary pulley in a direction which i
Charles Marcus
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
LandOfFree
Oil pressure control for continuously variable transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oil pressure control for continuously variable transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oil pressure control for continuously variable transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3027704