Interrelated power delivery controls – including engine control – Transmission control – With clutch control
Reexamination Certificate
1999-06-03
2001-05-08
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
With clutch control
C477S086000, C477S174000
Reexamination Certificate
active
06227998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power transmission arrangement for a vehicle.
2. Description of the Related Art
An automatically and hydraulically controlled wet multiplate clutch is well known in the art for transmitting a drive force or power of an engine to a transmission. As illustrated in
FIG. 6
of the accompanying drawings, this type of clutch generally includes a plurality of clutch plates (i.e., drive plates
114
and driven plates
111
) housed in a clutch housing
116
, and a clutch piston
120
for pushing the drive and driven plates against each other to engage the clutch. An oil pressure controlled to an appropriate value is fed to the clutch piston
120
through an oil passage
119
as indicated by the arrow. When the oil pressure is released, the clutch piston
120
is returned back by a return spring
121
such that the engaging force no longer acts on the clutch plates to disengage the clutch.
The clutch housing
116
is an input side of the clutch, and an input shaft
118
of the clutch is operatively connected to a crankshaft (not shown) of an engine to obtain a power from the engine. An output shaft
113
rotatably extends in the clutch housing
116
. The output shaft
113
is an output side of the clutch and operatively coupled to an input shaft (not shown) of a transmission. The drive plates
114
are mounted on the clutch housing
116
, and the driven plates
111
are attached to the output shaft
113
via a clutch holder
112
. The clutch plates are mounted or attached to the associated parts by way of splines.
Referring to
FIG. 7
of the accompanying drawings, illustrated is an oil pressure feed system. An oil pump
125
is driven by the engine to draw an oil from an oil tank
126
and feed the oil toward the clutch piston
120
and other components to be lubricated. On its way, the oil is controlled in flow rate and pressure by adjustable (or variable) metering valves
127
and
128
. Feeding and releasing of the oil to and from the clutch piston
120
are determined by an electromagnetic switching valve
129
. A reference numeral
130
designates a relief valve.
In the wet multi-plate clutch, the clutch plates are included in the above-mentioned “other components to be lubricated”, so that the lubrication oil is fed to the clutch plates. This lubrication oil feeding is necessary to allow friction heat generated upon clutch engagement to escape via the oil. In this manner, the clutch plates are oil cooled. Therefore, it is possible for the clutch to slip in a longer period in the wet multi-plate clutch than a dry friction clutch.
If the wet multi-plate clutch is employed and an automatic clutch system for automatic clutch engaging and disengaging is incorporated in a vehicle, it is possible to cause the clutch to slip for a relatively long period during vehicle starting so that it is in turn possible to select a relatively high gear position from the beginning.
However, if the gear position is too high at the starting or the starting with a high gear position is repeatedly experienced, the clutch will soon be deteriorated.
The present assignee proposed an arrangement which combines a torque converter with a wet multi-plate clutch (Japanese Patent Application, Laid-Open Publication No. 10-184726). A shock generated upon automatic clutch engagement is absorbed in this arrangement, so that complicated clutch engagement control is not needed during the starting (particularly sudden starting or rapid acceleration). However, even if this arrangement is employed, an excessively large load acts on the torque converter if the starting with a high gear position is repeated. As a result, the torque converter oil and/or torque converter itself will be damaged in a reduced period. In addition, if the same oil is commonly used as the clutch lubrication oil and the torque converter oil, deterioration of the torque converter oil promotes deterioration of the clutch.
SUMMARY OF THE INVENTION
An object of the present invention is to prevent the starting of a vehicle with an excessively high gear position.
Another object of the present invention is to prevent repetition of the starting with a relatively high gear position.
Still another object of the present invention is to prevent deterioration of a clutch and protect the clutch.
Yet another object of the present invention is to reduce a torque converter load when a torque converter is combined with a wet multi-plate clutch.
Another object of the present invention is to prevent degradation of a torque converter oil and torque converter itself.
Another object of the present invention is to prohibit deterioration of a clutch caused by deterioration of a torque converter oil.
Another object of the present invention is to prevent the controlling from being affected by oil deterioration.
Still another object of the present invention is to prevent a vehicle from moving backward on an upward slope when the above described controlling for clutch protection is performed.
According to one aspect of the present invention, there is provided a power transmission arrangement for a vehicle including a wet multi-plate clutch adapted to transmit a drive force or power of an engine to a transmission, and a control unit for automatically disengaging and engaging the clutch and for interrupting (or not carrying out) clutch engagement if a transmission gear position other than a predetermined one is selected for the starting of the vehicle when a vehicle is stopped.
Preferably, a torque converter is coupled with the clutch in series. The clutch may be hydraulically controlled. A single oil may preferably be used as a clutch lubrication oil, an oil used for controlling and a torque converter oil. The control unit may be an electronic controller.
According to a second aspect of the present invention, there is provided a power transmission arrangement for a vehicle including a wet multi-plate clutch adapted to transmit a power of an engine to a transmission, and a control unit for automatically disengaging and engaging the clutch normally but not for engaging the clutch if a transmission gear position other than a predetermined one is selected for the starting and a brake is operating when a vehicle is stopped.
Preferably, the brake may be a hand brake or a braking force holding device (hereinafter referred to as “hill start aid” or HSA device) used to stop and restart a vehicle on an upward slope.
According to a third aspect of the present invention, there is provided a vehicle power transmission arrangement including a wet multi-plate clutch and torque converter adapted in combination to transmit a power of an engine to a transmission, the torque converter provided in series with the clutch, and a control unit for automatically engaging and disengaging the clutch and for controlling the engine according to stamping of an accelerator pedal. The control unit starts clutch engagement when an engine revolution speed reaches a prescribed value as a result of stamping of the accelerator pedal from a vehicle stopped condition. The control unit, however, interrupts or does not carry out the clutch engagement if a transmission gear position other than a predetermined one is selected for the vehicle starting and a brake is operating when the vehicle is stopped. If the brake is not being applied, the control unit allows the clutch engagement, and causes the engine to rotate at a low revolution speed below the prescribed revolution value regardless of stamping of the accelerator pedal.
An accelerator sensor may be provided for outputting an accelerator signal in response to stamping of the accelerator pedal (or according to a stamping stroke). The control unit may control the engine based on the accelerator signal. The control unit may also maintain the engine revolution speed at a low speed below the prescribed value by disregarding the accelerator signal. The brake may be a hand brake or an auxiliary device used for restarting on a slope such as HSA.
According to a fourth aspect of the pres
Iwao Nobuyuki
Yamamoto Yasushi
Estremsky Sherry
Isuzu Motors Limited
McCormick Paulding & Huber LLP
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