U.S. patent application number 10/838861 was filed with the patent office on 2005-02-24 for high torque capacity wet paper friction member.
This patent application is currently assigned to Dynax Corporation. Invention is credited to Kawabata, Masataka, Kimura, Mutsuko, Suzuki, Atsushi, Takakura, Norio.
Application Number | 20050039872 10/838861 |
Document ID | / |
Family ID | 33505436 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050039872 |
Kind Code |
A1 |
Kimura, Mutsuko ; et
al. |
February 24, 2005 |
High torque capacity wet paper friction member
Abstract
[Problems]To provide a wet paper friction member which has high
torque capacity and excellent thermal stability simultaneously.
[Solution Means]A wet paper friction member is produced by
impregnating thermosetting resin into a paper body; curing it with
heat; and then forming it with pressure. A fiber base material
comprises 20-80 wt % of the paper body and comprises cellulose
pulp, aramid pulp, and homopolymer acrylic pulp the drainability of
which is adjusted to 120-280 ml, and thermosetting resin such as
straight phenol resin, alkyl modified phenol resin, epoxy modified
phenol resin, tung oil modified phenol resin, cashew oil modified
phenol resin, tung oil/cashew modified phenol resin is impregnated
at 20-40 wt %, and thereby, high torque capacity and heat
resistance, and mechanical strength are realized
simultaneously.
Inventors: |
Kimura, Mutsuko; (Hokkaido,
JP) ; Takakura, Norio; (Hokkaido, JP) ;
Kawabata, Masataka; (Toyota-shi, JP) ; Suzuki,
Atsushi; (Okazaki-shi, JP) |
Correspondence
Address: |
HOWSON AND HOWSON
ONE SPRING HOUSE CORPORATION CENTER
BOX 457
321 NORRISTOWN ROAD
SPRING HOUSE
PA
19477
US
|
Assignee: |
Dynax Corporation
Chitose-shi
JP
Toyota Motor Corporation
Toyota-shi
JP
|
Family ID: |
33505436 |
Appl. No.: |
10/838861 |
Filed: |
May 4, 2004 |
Current U.S.
Class: |
162/135 ;
162/146; 162/205; 428/147 |
Current CPC
Class: |
D21H 13/10 20130101;
Y10T 428/24405 20150115 |
Class at
Publication: |
162/135 ;
162/205; 162/146; 428/147 |
International
Class: |
D21H 013/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 8, 2003 |
JP |
129718/2003 |
Claims
1. A wet paper friction member which is produced by impregnating
thermosetting resin into a paper body; curing it by heating; and
forming it with pressure, wherein said paper body comprises fiber
base material and filler, characterized in that said fiber base
material comprises 20-80 wt % of said paper body and comprises
cellulose pulp, aramid pulp, and homopolymer acrylic pulp the
drainability of which is 120-280 ml.
2. A wet paper friction member as claimed in claim 1, wherein said
thermosetting resin comprises any one of some of resins among
straight phenol resin, alkyl modified phenol resin, epoxy modified
phenol resin, tung oil modified phenol resin, cashew oil modified
phenol resin, tung oil/cashew oil modified phenol resin.
3. Cancelled
4. A wet paper friction member as claimed in claim 1, wherein said
thermosetting resin comprises 20-40 wt % of said friction
member.
5. A wet paper friction member as claimed in claim 2, wherein said
thermosetting resin comprises 20-40 wt % of said friction member.
Description
DETAILED DESCRIPTION OF THE INVENTION
[0001] 1. Technical Field to Which the Invention Belongs
[0002] The present invention relates to a wet or wet-tpype paper
friction member used in a clutch and brake component of an
automatic transmission of a vehicle.
[0003] 2. Prior Art
[0004] A wet paper friction member is produced by dispersing a
mixture of a fiber base material such as pulp and a friction
modifier in water and forming a paper body; making it dry and
thereafter, impregnating it with thermosetting resin; heating and
curing it; and then forming it with pressure. The functions of a
wet paper friction member are influenced by a blend of the fiber
base material, a filler and the friction modifier etc. which are
main components of the paper body, and impregnated thermosetting
resin. Therefore, choice and blending amount of materials have been
researched for improvement of a wet paper friction member according
to its use.
[0005] It has been known that a friction modifier has an important
role in influencing porosity and surface configuration of a
friction member; and fiber ingredient affects porosity and
flexibility of the friction member and thus, has an influence on
friction property and heat resistance, and mechanical strength.
[0006] Phenol resin which is used mainly as a binder has an
influence not only on mechanical strength of a friction member but
also on frictional coefficient as well as velocity dependence of
the frictional coefficient. Particularly, since frictional
coefficient in the low velocity range which is referred to as
`torque capacity` is highly influenced by resin, the research has
been made using various oil-based materials or modified
materials.
[0007] For example, Patent Document 1 discloses a wet paper
friction member which is produced by blending pulp which is
fibrillated poly-acrylonitrile-based copolymer acrylic fiber
(hereinafter referred to as the `copolymer acrylic pulp`) and
filler, and thus, forming a paper body; and impregnating it with
thermosetting resin and then curing it.
[0008] [Patent Document 1]
[0009] Japanese Patent Publication No. 45808/1993
PROBLEMS TO BE SOLVED BY THE INVENTION
[0010] In a clutch and brake component of an automatic
transmission, the ability to transmit torque in the state where it
is stopped or slightly slides is the most fundamental function and
referred to as the torque capacity. If torque capacity is high, for
example, a diameter of a clutch can be reduced or the number of
friction members can be reduced and thus, a clutch component can be
miniaturized. On the other hand, calorific value per unit area of a
brake and a clutch during operation increases due to high
frictional coefficient. This tends to lower the heat resistance and
mechanical strength of the friction member; and therefore, a wet
paper friction member which is excellent in torque capacity, heat
resistance and mechanical strength could not be easily
produced.
[0011] As for the wet paper friction member of Patent Document 1,
copolymer acrylic pulp is particularly low in heat resistance and
chemical resistance, and therefore, contraction of dimension is
caused during processing step of a wet paper friction member.
Therefore, accurate processing has been difficult, or there have
been other problems such that large strength degradation of the
friction member is occurred during operation due to frictional heat
or chemicals in automatic transmission fluid.
[0012] In view of the above problems, it is an object of the
present invention to provide a wet paper friction member which is
used mainly in a clutch and a brake of an automatic transmission
and has high torque capacity and excellent thermal stability
simultaneously. Improvement was made by focusing attention on a
fiber base material and resin in a friction modifier forming a
paper body among compositions of a conventional wet paper friction
member. This realized successful development of a high torque
capacity wet paper friction member which has friction property,
heat resistance and mechanical strength simultaneously, and has
high versatility without limitation to its application.
MEANS TO SOLVE THE PROBLEM
[0013] The present invention solved the above-mentioned problems by
providing a wet paper friction member which is produced by
impregnating thermosetting resin into a paper body, curing it by
heat, and forming it with pressure, wherein said paper body
comprises fiber base material and filler, characterized in that
said fiber base material comprises 20-80 wt % of the total weight
of said paper body, and comprises cellulose pulp, aramid pulp, and
homopolymer acrylic pulp the drainability of which is 120-280
ml.
[0014] [Function]
[0015] The present invention can provide a wet paper friction
member having excellence in torque capacity, heat resistance and
mechanical strength since the fiber base material comprises 20-80
wt % of the total weight of the paper body, and comprises cellulose
pulp, aramid pulp, and homopolymer acrylic pulp the drainability of
which is 120-280 ml.
[0016] [Embodiments]
[0017] A wet paper friction member according to the present
invention is produced by blending specified fiber base material and
filler etc. and thus, producing a paper body; impregnating the
paper body with thermosetting resin; curing it by heating; and
forming it with pressure. The fiber base material comprises
cellulose pulp, aramid pulp, homopolymer acrylic pulp and other
fibers at 20-80 wt % of the total weight of the paper body.
Drainability of the homopolymer acrylic pulp is adjusted to 120-280
ml. Thermosetting resin such as straight phenol resin, alkyl
modified phenol resin, epoxy modified phenol resin, tung oil
modified phenol resin, cashew oil modified phenol resin and tung
oil/cashew oil modified phenol resin is impregnated into said paper
body at 20-40 wt %. Thus, high torque capacity, heat resistance and
mechanical strength are realized simultaneously.
[0018] The fiber base material comprises cellulose pulp, aramid
pulp, homopolymer acrylic pulp and other fiber at 20-80 wt % of the
total weight of the paper body.
[0019] While aramid pulp has excellent thermal stability and
paper-making property, it is expensive in comparison with cellulose
pulp, and also has inferior compatibility with thermosetting resin
such as phenol resin. In addition, while cellulose pulp has better
compatibility with resin and is cheaper in comparison with aramid
pulp, it is inferior in thermal stability and mechanical strength.
On the other hand, homopolymer acrylic pulp has excellent
compatibility with thermosetting resin such as phenol resin and has
a characteristic that it does not thermofuse. Therefore, when it is
used with aramid pulp and cellulose pulp, excellent thermal
stability and mechanical strength can be achieved at low cost. When
the amount of the fiber base material is above 80 wt % of the total
weight of the paper body, smooth member surface can not be
obtained. When it is below 20 wt %, mechanical strength is
lowered.
[0020] Drainability of homopolymer acrylic pulp forming a paper
body is adjusted to 120-280 ml.
[0021] Drainability is a degree of beating of fiber, and the
smaller drainability is, the larger the degree of beating of fiber
is, resulting in increase of splitting degree of each fiber. When
splitting degree of acrylic pulp is increased, intertwist between
fibers increases, and sufficient mechanical strength can be
obtained after phenol resin is impregnated and cured.
[0022] When homopolymer acrylic pulp the drainability of which is
smaller than 120 ml is used for the one forming a paper body, the
amount of split fiber is too large and the size of holes becomes
too small, and therefore, clogging tends to be caused during
frictional sliding, and heat resistance is lowered.
[0023] When aramid pulp the drainability of which is above 280 ml
is used for the one forming a paper body, intertwist between fibers
becomes small and therefore, sufficient mechanical strength can not
be obtained.
[0024] As thermosetting resin, any one or some of resins among
straight phenol resin, alkyl modified phenol resin, epoxy modified
phenol resin, tung oil modified phenol resin, cashew oil modified
phenol resin and tung oil/cashew oil modified phenol resin can be
used to be impregnated into said paper body at 20-40 wt %.
[0025] In general, tung oil modified phenol resin, cashew oil
modified phenol resin and tung oil/cashew oil modified phenol resin
etc. are known to be effective in increasing frictional coefficient
in the low velocity range. On the other hand, when such oil
modified materials are used, there are problems such that heat
resistance and mechanical strength are lowered. In the meantime,
straight phenol is not so effective in increasing frictional
coefficient in the low velocity range, but, it has sufficient heat
resistance and mechanical strength. Therefore, when it is used with
the above-mentioned modified materials, high frictional coefficient
and heat resistance, as well as mechanical strength can be achieved
simultaneously. When the amount of these resins impregnated with a
paper body was under 20 wt % of the total weight of the friction
member, sufficient mechanical strength can not be obtained, and
when it is 40 wt % or more, heat resistance is lowered.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] [FIG. 1] A graph showing the results of torque capacity
evaluation;
[0027] [FIG. 2] A graph showing the results of durability
evaluation;
[0028] [FIG. 3] A graph showing the results of durability
evaluation; and
[0029] [FIG. 4] A graph showing the results of compressive strength
evaluation.
EXAMPLES
[0030] Examples will be explained concretely below.
Example
[0031] A clutch disk was produced by impregnating oil modified
straight phenol resin into a paper body comprising 10 wt % of
cellulose pulp, 10 wt % of aramid pulp, 30 wt % of homopolymer
acrylic pulp, and 50% of filler such as diatomaceous earth, at 30
wt % of a friction member; curing it by heating, and then bonding
it to a core plate.
Comparative Example
[0032] As Comparative Example, a clutch disk was produced by
impregnating straight phenol resin into a paper body comprising 30
wt % of cellulose pulp, 30 wt % of aramid pulp, 30 wt % of
diatomaceous earth, and 10 wt % of carbon-based filler, at 35 wt %
of a friction member; curing it by heating; and then bonding it to
a core plate.
[0033] Torque capacity, heat resistance and mechanical strength of
a wet friction clutch disc produced by the above-mentioned
processes were evaluated by the following testing methods:
[0034] <Conditions for Torque Capacity Evaluation>
[0035] Testing device: SAE No. 2 friction testing apparatus
[0036] Condition for achieving performance: number of friction
surfaces: 6
[0037] Oil temperature: 80 degrees Celsius
[0038] Surface pressure: 0.5 MPa, 1.0 MPa, 2.0 MPa
[0039] Rotational speed: 0.72, 1, 5, 10, 25, 50, 75, 100 rpm
[0040] As a result of the above tests, a wet paper friction member
of Example had high frictional coefficient at low speed, that is,
high torque capacity, and also had excellent velocity property of
the frictional coefficient.
[0041] <Condition for High-Speed Durability Evaluation>
[0042] Testing device: SAE No. 2 friction testing apparatus
[0043] Condition for achieving performance: number of friction
surfaces: 6
[0044] Oil temperature: 100 degrees Celsius
[0045] Surface pressure: 0.785 MPa
[0046] Rotational speed: 7100 rpm
[0047] Inertial mass: 0.01 Kg.multidot.m/s.sup.2
[0048] Amount of lubricating oil: 360 ml/min
[0049] As a result of the above tests, a wet paper friction member
of Example had small deterioration of frictional coefficient, that
is, high heat resistance, and also had relatively small abrasion
loss after the test in comparison with Comparative Example as shown
in FIGS. 2 and 3.
[0050] <Condition for Compressive Strength Evaluation>
[0051] Testing device: repetitive compressive strength testing
apparatus
[0052] Condition for evaluation: number of friction surfaces: 2
[0053] Oil temperature: 120 degrees Celsius
[0054] Surface pressure: 10.0 MPa
[0055] Cycle: loading 2 sec, unloading 4 sec
[0056] As a result of the above tests, a wet paper friction member
of Example had relatively excellent mechanical strength in
comparison with Comparative Example as shown in FIG. 4.
[0057] It is known from FIGS. 1-4 that a friction member of Example
had high torque capacity along with sufficient heat resistance and
mechanical strength in comparison with a friction member of
Comparative Example
[0058] It is known from the above results that when a fiber base
body comprises cellulose pulp, aramid pulp, homopolymer acrylic
pulp and other fibers at 20-80 wt % of the total weight of a paper
body; drainability of homopolymer acrylic pulp is adjusted to
120-280 ml; and moreover, thermosetting resin such as straight
phenol resin, alkyl modified phenol resin, epoxy modified phenol
resin, tung oil modified phenol resin, cashew oil modified phenol
resin, tung oil/cashew oil modified phenol resin, is impregnated
into said papermaking body at 20-40 wt % of a friction member, high
torque capacity, heat resistance and mechanical strength are
achieved simultaneously. This high torque wet paper friction member
can be used for many wet friction applications.
ADVANTAGES OF THE INVENTION
[0059] According to the present invention, a fiber base material
comprises 20-80 wt % of the total weight of a papermaking body, and
comprises cellulose pulp, aramid pulp, and homopolymer acrylic pulp
the drainability of which is 120-280 ml, and thereby, the effects
of improving torque capacity, heat resistance and mechanical
strength of a wet paper friction member are achieved.
* * * * *