Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Reexamination Certificate
2000-12-12
2003-08-05
Marmor, Charles A. (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
C477S050000, C474S028000
Reexamination Certificate
active
06602160
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for hydraulically controlling a continuously variable transmission having a V-belt by adjusting the widths of grooves of input and output pulleys depending upon the engine torque. More particularly, the invention relates to a device for hydraulically controlling a continuously variable transmission, which improves fuel efficiency, automatically detects the slipping state of the V-belt and suppresses the slip.
2. Prior Art
There has heretofore been known a continuously variable transmission which variably sets a transmission gear ratio between the input and the output by stretching a V-belt between a pair of pulleys and adjusting the widths of grooves of the pulleys round which the V-belt is wrapped.
In the continuously variable transmission of this kind as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 42147/1988 and 272569/1992, movable conical plates provided for the pulleys are displaced by a hydraulic mechanism to vary the tension of the V-belt and the widths of grooves of the pulleys.
FIG. 7
is a diagram schematically illustrating the constitution of a general device for hydraulically controlling a V-belt type continuously variable transmission.
In
FIG. 7
, though widely known constitutional portions are not diagramed, an engine is equipped with an ignition device, and an intake pipe of the engine is equipped with a throttle valve and fuel injection valves.
The engine
1
and various actuators are equipped with various sensors (not shown) for detecting the operation conditions. Signals of various sensors are input to a controller
20
constituted by an ECU (electronic control unit).
A torque converter
3
having a damper clutch
2
is connected to the output side of the engine
1
, and a back-and-forth change-over clutch is connected to the output side of the torque converter
3
.
A CVT (continuously variable transmission)
5
is connected to the output side of the back-and-forth change-over clutch
4
, and tires
7
of an automobile are connected to the output side of the CVT
5
via a differential gear
6
.
The CVT
5
includes a first pulley
5
a
on the input side, a second pulley
5
b
on the output side, a V-belt
5
c
wrapped round between the first pulley
5
a
and the second pulley
5
b
, and hydraulic chambers
51
and
52
for adjusting the positions of the first pulley
5
a
and the second pulley
5
b
in the directions of arrows.
An oil pump
8
coupled to the engine
1
supplies an oil to the lubrication system of the engine
1
as well as to the hydraulic chambers
51
and
52
in the CVT
5
to adjust the CVT
5
.
A conduit communicated with the oil pump
8
is provided with a flow rate control valve
9
for controlling a first hydraulic pressure (primary pressure) supplied to the hydraulic chamber
51
and a pressure control valve
10
for controlling a secondary hydraulic pressure (line pressure) supplied to the hydraulic chamber
52
.
A conduit communicated with the hydraulic chamber
51
in the CVT
5
is provided with a primary pressure sensor
11
for detecting the primary pressure P
1
, a conduit communicated with the hydraulic chamber
52
in the CVT
5
is provided with a line pressure sensor
12
for detecting the line pressure P
2
, and the detected pressures P
1
and P
2
are input to the controller
20
like other various sensor signals.
The damper clutch
2
is provided with a direct-coupling duty solenoid
13
, and the back-and-forth change-over clutch
4
is provided with a clutch duty solenoid
14
.
Further, the flow rate control valve
9
is provided with a speed-change duty solenoid
15
, and the pressure control valve
10
is provided with a line-pressure duty solenoid
16
.
The duty solenoids
13
to
16
drive the damper clutch
2
, back-and-forth change-over clutch
4
, flow rate control valve
9
and pressure control valve
10
depending upon the control quantities from the controller
20
.
In controlling the CVT
5
, for example, the speed-change duty solenoid
15
drives the flow rate control valve
9
depending upon the primary pressure control amount C
1
(hereinafter simply referred to as “control amount”), and the line-pressure duty solenoid
16
drives the pressure control valve
10
depending upon the line pressure control amount C
2
(hereinafter simply referred to as “control amount”).
The shafts on the output side of the engine
1
is provided with first to third rotation sensors
17
to
19
for detecting the first to third rotational speeds N
1
to N
3
. The detected rotational speeds N
1
to N
3
are input to the controller
20
like other various sensor signals.
The first rotation sensor
17
is provided between the torque converter
3
and the back-and-forth changeover clutch
4
, the second rotation sensor
18
is provided between the back-and-forth change-over clutch
4
and the CVT
5
, and the third rotation sensor
19
is provided between the CVT
5
and the differential gear
6
.
Here, the second and third rotational speeds N
2
and N
3
stand for an input rotational speed and an output rotational speed of the CVT
5
.
The controller
20
controls the primary pressure P
1
and the line pressure P
2
(first and second hydraulic pressures) based upon the operation conditions of the engine
1
, input and output rotational speeds N
2
and N
3
of the CVT
5
, and detected values of the primary pressure P
1
and the line pressure P
2
(first and second real hydraulic pressures).
In
FIG. 7
, the driving force produced by the engine
1
is, first, transmitted to the CVT
5
via the torque converter
3
and the back-and-forth change-over clutch
4
.
At this moment, the back-and-forth change-over clutch
4
is changed over to forward, neutral or reverse by the clutch duty solenoid
14
.
The CVT
5
controls the transmission gear ratio relying upon the first pulley
5
a
, second pulley
5
b
and belt
5
c
, and transmits the output torque from the second pulley
5
b
to the tires
7
through the differential gear
6
.
The hydraulic pressure produced by the oil pump
8
is adjusted by the pressure control valve
10
and is supplied, as the line pressure P
2
, to the hydraulic chamber
52
of the second pulley
5
b.
Here, the pressure control valve
10
is controlled by the line-pressure duty solenoid
16
that is driven depending upon the control amount C
2
.
Further, the line pressure P
2
adjusted by the pressure control valve
10
is divided by the flow rate control valve
9
and is supplied, as the primary pressure P
1
, to the hydraulic chamber
51
of the first pulley
5
a.
At this moment, the flow rate control valve
9
is controlled by the speed-change duty solenoid
15
that is driven depending upon the control amount C
1
.
Thus, the primary pressure P
1
and the line pressure P
2
are adjusted to adjust the positions of the pulleys
5
a
and
5
b
, and the transmission gear ratio is set to a target value by the tension of the V-belt
5
c
and the CVT
5
.
FIG. 8
is a functional block diagram illustrating the constitution of the controller
20
in a conventional device for hydraulically controlling a continuously variable transmission, and shows an operation unit for determining a control amount C
2
for the line-pressure duty solenoid.
The controller
20
includes a CVT input torque detector unit
21
for detecting the torque Ti input to the CVT
5
, a CVT transmission-gear-ratio detector unit
22
for detecting the transmission gear ratio GR of the CVT
5
, a target line pressure operation unit
23
for operating a target line pressure Po
2
, and a PID operation unit
24
for operating the control amount C
2
of the line-pressure duty solenoid
16
.
The CVT transmission-gear-ratio detector unit
22
operates the real transmission gear ratio GR based on the second rotational speed N
2
(input rotational speed of the CVT
5
) detected by the second rotation sensor
18
and the third rotational speed N
3
(output rotational speed of the CVT
5
) detected by the third rotation senso
Lewis Tisha D.
Marmor Charles A.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
LandOfFree
Device for hydraulically controlling a continuously variable... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for hydraulically controlling a continuously variable..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for hydraulically controlling a continuously variable... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3113393