U.S. patent application number 10/996393 was filed with the patent office on 2005-06-02 for disc brake.
Invention is credited to Nanri, Keisuke.
Application Number | 20050115780 10/996393 |
Document ID | / |
Family ID | 34544872 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115780 |
Kind Code |
A1 |
Nanri, Keisuke |
June 2, 2005 |
Disc brake
Abstract
In a disc brake, a pair of pads are disposed on opposite sides
of a disc. A caliper body extends over the disc. A piston is
slidably held in the caliper body on a side opposite to the disc
relative to the corresponding pad. In the caliper body, a prepared
hole for a bore into which the piston is slidably fitted and a
recess extending from a bottom portion of the prepared hole
outwardly in a radial direction of the prepared hole are formed by
means of a core during casting. A linear passage opening is formed
by cutting from an exterior surface of the caliper body so as to
communicate with the recess. In this disc brake, an opening for
forming a brake fluid passage can be easily formed by machining,
resulting in high production efficiency. The position of the
opening can be determined with a high degree of freedom of
design.
Inventors: |
Nanri, Keisuke;
(Yamanashi-ken, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
34544872 |
Appl. No.: |
10/996393 |
Filed: |
November 26, 2004 |
Current U.S.
Class: |
188/73.46 ;
188/72.4 |
Current CPC
Class: |
F16D 2055/0091 20130101;
Y10T 29/49989 20150115; F16D 55/228 20130101; F16D 2055/0016
20130101; F16D 2250/0007 20130101; F16D 2055/002 20130101 |
Class at
Publication: |
188/073.46 ;
188/072.4 |
International
Class: |
F16D 055/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2003 |
JP |
399553/2003 |
Claims
What is claimed is:
1. A disc brake comprising: a pair of pads disposed on opposite
sides of a disc; a caliper disposed so as to extend over the disc,
the caliper being adapted to be mounted on a vehicle body; and at
least one piston slidably held in the caliper, the piston being
located on a side opposite to the disc relative to the
corresponding pad, the caliper including: a prepared hole to be
machined to form at least one bore into which the piston is
slidably fitted, a recess extending from a bottom portion of the
prepared hole outwardly in a radial direction of the prepared hole,
the prepared hole and the recess being formed by means of a core
when the caliper is cast, and a linear passage opening formed so as
to extend from an exterior surface of the caliper to the
recess.
2. A disc brake according to claim 1, wherein: the caliper includes
a plurality of said bores arranged in a spaced relationship in a
direction of rotation of the disc and a communication passage for
communication between each pair of adjacent bores, the
communication passages being formed in the caliper by means of said
core when the caliper is cast: said recess is formed at a position
corresponding to the top of the uppermost bore of said plurality of
bores when the caliper is mounted on the vehicle body; and said
passage opening is formed so as to extend from the exterior surface
of a portion of the caliper that is located at an upper position
when the caliper is mounted on the vehicle body.
3. A disc brake according to claim 2, wherein: said plurality of
bores are disposed on each of the opposite sides of the disc in an
axial direction of the disc; and a linear communication opening is
formed so as to extend from the exterior surface of the caliper and
to intersect said passage opening, the communication opening being
adapted to form a part of a connection passage for allowing
communication between the bores disposed on the opposite sides of
the disc in the axial direction of the disc.
4. A disc brake according to claim 1, wherein: the caliper includes
an inner-side cylinder portion and an outer-side cylinder portion,
each having the bore into which the piston is slidably fitted, the
inner-side and outer-side cylinder portions being formed as a
one-piece member by casting; and all the bores are formed by
machining from portions thereof on a side of a space between the
inner-side cylinder portion and the outer-side cylinder portion, to
thereby maintain a closed state of bottom portions of all the bores
obtained by casting.
5. A disc brake according to claim 4, wherein: the prepared holes
to be machined to form the bores have inmost recess portions
located at the bottom portions of the bores and having a larger
diameter than inner-diameter portions of the bores and, wherein,
said prepared holes, said inmost portions and said recesses
extending from the inmost recess portions outwardly in a radial
direction thereof, are formed by means of the core when the caliper
is cast; and the inner-diameter portions of the bores are formed by
machining said prepared holes from portions thereof on a side of
the space between the inner-side cylinder portion and the
outer-side cylinder portion.
6. A disc brake according to claim 1, wherein said prepared hole
has an inmost recess portion located at a bottom portion of the
bore and having a larger diameter than an inner-diameter portion of
the bore and wherein, said prepared hole, said inmost recess
portion and said recess extending from the inmost recess portion
outwardly in a radial direction thereof, are formed by means of the
core when the caliper is cast.
7. A disc brake according to claim 1, wherein: the caliper includes
a plurality of said bores arranged in a spaced relationship in a
direction of rotation of the disc and each bore has an inmost
recess portion located at bottom portion of the bore and having a
larger diameter than an inner-diameter portion of the bore; and the
prepared holes to be machined to form the bores, inmost recess
portions, the recess extending from at least one of the inmost
recess portions outwardly in a radial direction thereof as well as
a communication passage for communication between the inmost recess
portions of the adjacent bores, are formed by means of the core
when the caliper is cast.
8. A disc brake according to claim 1, wherein said recess extends
from part of the circumference of the bottom portion of the
corresponding prepared hole.
9. A disc brake according to claim 5, wherein said recess extends
from part of the circumference part of the corresponding inmost
recess portion.
10. A disc brake according to claim 1, wherein said passage opening
is communicated with a distal end of the recess extending from the
prepared hole outwardly in the radial direction thereof.
11. A disc brake according to claim 6, wherein said passage opening
is communicated with a distal end of the recess extending from the
prepared hole outwardly in the radial direction thereof.
12. A disc brake according to claim 8, wherein a proximal end of
the recess extends, outwardly in a radial direction of the disc
along the circumference of the bottom portion, from a position
corresponding to the center axis of the corresponding bore or a
position located inwardly from the center axis of the corresponding
bore as viewed in the radial direction of the disc.
13. A disc brake according to claim 9, wherein a proximal end of
the recess extends, outwardly in a radial direction of the disc
along the circumference of the inmost recess portion, from a
position corresponding to the center axis of the corresponding bore
or a position located inwardly from the center axis of the
corresponding bore as viewed in the radial direction of the
disc.
14. A disc brake according to claim 1, wherein a bleeder mount
opening for mounting of a bleeder valve for release of air is
formed in the passage opening on a side opposite to the recess.
15. A disc brake according to claim 2, wherein a bleeder mount
opening for mounting of a bleeder valve for release of air is
formed in the passage opening on a side opposite to the recess.
16. A disc brake according to claim 1, wherein the passage opening
extends between a mounting bolt opening extending in a radial
direction of the disc and a pad-mounting space.
17. A disc brake according to claim 6, wherein the passage opening
extends between a mounting bolt opening extending in a radial
direction of the disc and a pad-mounting space.
18. A disc brake according to claim 8, wherein a distal end of the
recess is located outwardly from a region occupied by the
corresponding bore bottom portion as viewed in a direction of
rotation of the disc, while being located radially outwardly from
the center axis of the corresponding bore as viewed in a radial
direction of the disc.
19. A disc brake according to claim 9, wherein a distal end of the
recess is located outwardly from a region occupied by the
corresponding inmost recess portion as viewed in a direction of
rotation of the disc, while being located radially outwardly from
the center axis of the corresponding bore as viewed in a radial
direction of the disc.
20. A disc brake according to claim 8, wherein a proximal end of
the recess extends, outwardly in a radial direction of the disc
along the circumference of the bottom portion, from a position
located on a gravity line drawn from the center axis of the bore in
a direction parallel to the direction of gravity when the caliper
is mounted on a vehicle, wherein the intersection of the gravity
line and the circumference of the bore near an inner end of the
linear passage opening communicating with the recess is closer to
the center of the disc than an intersection of a radius line drawn
from the center of the bore to the inner end of the linear passage
opening and the circumference, or on the same side of said line as
the center of the disc.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a disc brake for a
vehicle.
[0002] In a disc brake for a vehicle, a pair of pads are disposed
on opposite sides of a disc, and pistons, each of which is disposed
on a side opposite to the disc relative to the corresponding pad,
are adapted to press the pads against the disc, to thereby apply a
braking force to the vehicle. The pistons are slidably fitted into
bores formed in a caliper body. In a disc brake of this type
disclosed in U.S. Pat. No. 6,367,595, a bottom portion of each of
the bores for the pistons is formed by a member externally attached
to an open end of the bore. Before the open end of the bore is
closed by this bottom portion, a tool is inserted from the open end
of the bore, and a passage opening is formed by cutting from a
portion in the bore on a side of the bottom portion thereof, and
then the bore is closed by threadably engaging the bottom portion
with the caliper body.
[0003] In the above-mentioned disc brake, however, the passage
opening must be formed by cutting from a predetermined position in
the bore while avoiding interference with the open end of the bore
before it is closed. Therefore, the passage opening must be formed
with high machining accuracy, and an operation for forming the
passage opening becomes cumbersome. This lowers production
efficiency. Further, since the passage opening must be formed while
avoiding interference with the open end of the bore, a degree of
freedom of design when determining the position of the passage
opening is low.
SUMMARY OF THE INVENTION
[0004] Therefore, it is an object of the present invention to
provide a disc brake in which an opening for forming a brake fluid
passage can be easily formed, thus achieving high production
efficiency, and which enables the position of the opening for the
brake fluid passage to be determined with a high degree of freedom
of design.
[0005] In order to achieve the above-mentioned object, the present
invention provides a disc brake comprising a pair of pads disposed
on opposite sides of a disc, a caliper disposed so as to extend
over the disc, the caliper being adapted to be mounted on a vehicle
body, and at least one piston slidably held in the caliper, the
piston being located on a side opposite to the disc relative to the
corresponding pad. The caliper includes a prepared hole to be
machined to form at least one bore into which the piston is
slidably fitted, and a recess extending from a bottom portion of
the prepared hole outwardly in a radial direction of the prepared
hole. The prepared hole and the recess are formed by means of a
core when the caliper is cast. A linear passage opening is formed
so as to extend from an exterior surface of the caliper to the
recess.
[0006] According to one embodiment of the present invention, the
caliper includes a plurality of bores arranged in a spaced
relationship in a direction of rotation of the disc, and a
communication passage for communication between the adjacent bores
is formed in the caliper by means of the core when the caliper is
cast. The recess is formed at a position corresponding to the top
of the uppermost bore when the caliper is mounted on the vehicle
body. The passage opening is formed so as to extend from the
exterior surface of a portion of the caliper that is located at an
upper position when the caliper is mounted on the vehicle body.
[0007] According to another embodiment of the present invention,
the plurality of bores are disposed on each of opposite sides of
the disc in an axial direction of the disc, and a linear
communication opening is formed so as to extend from the exterior
surface of the caliper and to intersect the passage opening. The
communication opening is adapted to form a part of a connection
passage for allowing communication between the bores disposed on
opposite sides of the disc in the axial direction of the disc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a front view showing a disc brake according to an
embodiment of the present invention.
[0009] FIG. 2 is a side view showing the disc brake according to
the embodiment of the present invention.
[0010] FIG. 3 is a perspective view showing the disc brake
according to the embodiment of the present invention.
[0011] FIG. 4 is a front view showing a core for producing a
caliper body in the disc brake according to the embodiment of the
present invention.
[0012] FIG. 5 is a plan view showing the core for producing the
caliper body in the disc brake according to the embodiment of the
present invention.
[0013] FIG. 6 is a left side view showing the core for producing
the caliper body in the disc brake according to the embodiment of
the present invention.
[0014] FIG. 7 is a plan view of a casting of the caliper body in
the disc brake according to the embodiment of the present
invention.
[0015] FIG. 8 is a front view of the casting of the caliper body in
the disc brake according to the embodiment of the present
invention.
[0016] FIG. 9 is a bottom view of the casting of the caliper body
in the disc brake according to the embodiment of the present
invention.
[0017] FIG. 10 is a cross-sectional view of the casting of the
caliper body in the disc brake according to the embodiment of the
present invention, taken along the line B1-B1 in FIG. 8.
[0018] FIG. 11 is a cross-sectional view of the casting of the
caliper body in the disc brake according to the embodiment of the
present invention, taken along the line A1-A1 in FIG. 7.
[0019] FIG. 12 is a cross-sectional view of the casting of the
caliper body in the disc brake according to the embodiment of the
present invention, taken along the line A2-A2 in FIG. 7.
[0020] FIG. 13 is a cross-sectional view of the casting of the
caliper body in the disc brake according to the embodiment of the
present invention, taken along the line C1-C1 in FIG. 8.
[0021] FIG. 14 is a left side view of the casting of the caliper
body in the disc brake according to the embodiment of the present
invention.
[0022] FIG. 15 is a right side view of the casting of the caliper
body in the disc brake according to the embodiment of the present
invention.
[0023] FIG. 16 is a plan view of the caliper body in the disc brake
according to the embodiment of the present invention.
[0024] FIG. 17 is a front view of the caliper body in the disc
brake according to the embodiment of the present invention.
[0025] FIG. 18 is a bottom view of the caliper body in the disc
brake according to the embodiment of the present invention.
[0026] FIG. 19 is a cross-sectional view of the caliper body in the
disc brake according to the embodiment of the present invention,
taken along the line B2-B2 in FIG. 17.
[0027] FIG. 20 is a cross-sectional view of the caliper body in the
disc brake according to the embodiment of the present invention,
taken along the line B3-B3 in FIG. 17.
[0028] FIG. 21 is a cross-sectional view of the caliper body in the
disc brake according to the embodiment of the present invention,
taken along the line A3-A3 in FIG. 16.
[0029] FIG. 22 is a cross-sectional view of the caliper body in the
disc brake according to the embodiment of the present invention,
taken along the line A4-A4 in FIG. 16.
[0030] FIG. 23 is a cross-sectional view of the caliper body in the
disc brake according to the embodiment of the present invention,
taken along the line C2-C2 in FIG. 17.
[0031] FIG. 24 is a left side view of the caliper body in the disc
brake according to the embodiment of the present invention.
[0032] FIG. 25 is a right side view of the caliper body in the disc
brake according to the embodiment of the present invention.
[0033] FIG. 26 is an enlarged cross-sectional view of an essential
part of the caliper body in the disc brake according to the
embodiment of the present invention, taken along the line B2-B2 in
FIG. 17.
[0034] FIG. 27 is a cross-sectional view of the caliper body in the
disc brake according to a second embodiment of the present
invention, taken along the line B4-B4 in FIG. 28.
[0035] FIG. 28 is a cross-sectional view of the caliper body in the
disc brake according to the second embodiment of the present
invention, taken along the line A5-A5 in FIG. 27.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Hereinbelow, embodiments of the present invention are
described, referring to the drawings.
[0037] In FIGS. 1 and 2, reference numeral 1 denotes an
opposed-piston type disc brake. A caliper 11 of this disc brake is
an opposed-piston type caliper 11. The caliper 11 comprises a
caliper body 16 which extends over a disc 12, as shown in FIG. 1,
and which is mounted on a mount portion 14 of a front fork 13 as a
non-rotational portion of a body of a vehicle (a motor cycle in
this embodiment), as shown in FIG. 2. The caliper 11 further
comprises a plurality of pairs (two pairs in this embodiment) of
pistons 17 slidably provided in the caliper body 16, so as to face
each other with the disc 12 being disposed therebetween. In the
following description, a radial direction of the disc 12, an axial
direction of the disc 12, a direction of rotation of the disc 12
refer to those in a state in which the caliper body is mounted on a
vehicle body. In FIGS. 1 and 2, an arrow R indicates the direction
of rotation of the disc 12 when a vehicle travels in a forward
direction.
[0038] As shown in FIGS. 1 to 3, the caliper body 16 is a one-piece
member comprising an outer-side cylinder portion 20 disposed on an
outer side of the disc 12 (a side opposite to a wheel) and an
inner-side cylinder portion 21 disposed on an inner side of the
disc 12 (a side on which a wheel is provided). The caliper body 16
further comprises a plurality (three in this embodiment) of
outer-side torque bearing portions 23 projecting from the
outer-side cylinder portion 20 towards the inner side of the disc,
the outer-side torque bearing portions 23 being arranged in a
spaced relationship in a direction of rotation of the disc 12, a
plurality (three in this embodiment) of inner-side torque bearing
portions 24 projecting from the inner-side cylinder portion 21
towards the outer side of the disc, the inner-side torque bearing
portions 24 being arranged in a spaced relationship in a direction
of rotation of the disc 12, and a plurality (three in this
embodiment) of disc pass portions 26, each connecting the
outer-side torque bearing portion 23 and the inner-side torque
bearing portion 24 corresponding to each other in terms of a
position in the direction of rotation of the disc. That is, in the
caliper body 16, the outer-side torque bearing portions 23 and the
inner-side torque bearing portions 24 are provided between the
outer-side cylinder portion 20 and the inner-side cylinder portion
21, and the disc pass portions 26 are provided between the
outer-side torque bearing portions 23 and the inner-side torque
bearing portions 24 and connect the outer-side torque bearing
portions 23 and the inner-side torque bearing portions 24.
[0039] Therefore, in the caliper body 16, a plurality (three in
this embodiment) of portions are arranged in a spaced relationship
in a direction of rotation of the disc 12, each of which portions
comprises the outer-side torque bearing portion 23, the disc pass
portion 26 and the inner-side torque bearing portion 24 extending
in an axial direction of the disc 12. A pad-mounting space 28 is
formed between each pair of adjacent ones of these portions, which
space 28 has an opening facing in a radial direction of the disc
12. There are provided a plurality (two in this embodiment) of
pad-mounting spaces 28 arranged in a direction of rotation of the
disc.
[0040] In the caliper body 16, opposed surfaces 20a and 21a of the
outer-side and inner-side cylinder portions 20 and 21 face each
other through each pad-mounting space 28. A pad pin 30 extends in
an axial direction of the disc through the pad-mounting space 28
between the opposed surfaces 20a and 21a.
[0041] Bores 31 are formed in the opposed surfaces 20a and 21a of
the outer-side and inner-side cylinder portions 20 and 21, which
surfaces face each other through each pad-mounting space 28. Each
bore 31 has a center axis parallel to an axial direction of the
disc. The pistons 17 are fitted into inner-diameter portions 32 of
the bores 31. Thus, a plurality of pairs (two pairs in this
embodiment) of bores 31 are arranged in a direction of rotation of
the disc, with the bores 31 of each pair facing each other in an
axial direction of the disc. A plurality of pairs (two pairs in
this embodiment) of pistons 17 are arranged in a direction of
rotation of the disc, with the pistons 17 of each pair facing each
other in an axial direction of the disc.
[0042] A pair of pads 33 are supported on each pad pin 30 of the
caliper body 16. Thus, totally two pairs of pads 33 are provided in
the caliper body 16. The pads 33 are adapted to slidably move in an
axial direction of the disc. The pads 33 are respectively disposed
on opposite sides of the disc 12 in an axial direction of the disc.
The pistons 17, each of which is disposed on a side opposite to the
disc 12 relative to the corresponding pad 33, are adapted to press
the pads 33 against the disc 12, thus applying a braking force to
the vehicle.
[0043] A braking torque during braking when the vehicle travels in
a forward direction acts as a force which moves the pads 33 from an
entrance side of the disc 12 in a direction of rotation of the disc
(hereinafter, referred to simply as "the entrance side of the
disc") to an exit side of the disc 12 in the direction of rotation
of the disc (hereinafter, referred to simply as "the exit side of
the disc"). This force is transmitted from the pair of pads 33 on
the exit side of the disc to the caliper body 16 through the
outer-side torque bearing portion 23 and the inner-side torque
bearing portion 24 which are located most closely to the exit side
of the disc and abut against these pads 33. The force is also
transmitted from the pair of pads 33 on the entrance side of the
disc to the caliper body 16 through the outer-side torque bearing
portion 23 and the inner-side torque bearing portion 24 which are
located at an intermediate position in a direction of rotation of
the disc and abut against these pads 33. When the vehicle travels
in a backward direction, a braking torque during braking is
transmitted from the pads 33 to the caliper body 16 through the
outer-side torque bearing portions 23 and the inner-side torque
bearing portions 24 which abut against the pads 33 on a side
opposite to those which abut against the pads 33 when the vehicle
travels in a forward direction.
[0044] As shown in FIG. 2, an inner side (as viewed in a radial
direction of the disc) of the disc pass portion 26 of the caliper
body 16 includes a pass recess 34 in which the disc 12 is provided.
The outer-side torque bearing portion 23 and the inner-side torque
bearing portion 24 extend beyond the disc pass portion 26 inwardly
in a radial direction of the disc, so as to enable the torque from
the pads 33 disposed in an overlapping relation to the disc 12 in a
radial direction of the disc to be received in a direction of
rotation of the disc. That is, a wall thickness of the disc pass
portion 26 in a radial direction of the disc is smaller than that
of each of the outer-side torque bearing portion 23 and the
inner-side torque bearing portion 24.
[0045] In the pad-mounting space 28, a pad spring 35 is disposed so
as to bias the pads 33 inwardly in a radial direction of the
disc.
[0046] Thus, the disc brake 1 comprises a pair of pads 33 disposed
on opposite sides of the disc 12, a caliper body 16 disposed so as
to extend over the disc 12, and pistons 17, each of which is
slidably held on a side opposite to the disc 12 relative to the
corresponding pad 33. A plurality of bores 31 are disposed in a
spaced relationship in a direction of rotation of the disc. An
inner-side torque bearing portion 24, a disc pass portion 26 and an
outer-side torque bearing portion 23 are disposed between the bores
31 adjacent to each other in a direction of rotation of the
disc.
[0047] The outer-side cylinder portion 20 of the caliper body 16
includes a plurality (two in this embodiment) of mounting bolt
openings 37 for mounting of the caliper 11 on the mount portion 14
of the front fork 13. The mounting bolt openings 37 are formed in
parallel to each other in the radial direction of the disc. The
outer-side cylinder portion 20 of the caliper body 16 includes a
pipe mount opening 38 for mounting of a brake pipe, which opening
extends in an axial direction of the disc. The pipe mount opening
38 is formed at a position which corresponds to an upper position
when the caliper body is mounted on the front fork 13 and which is
located on the exit side of the disc during braking when the
vehicle travels in a forward direction. A bleeder mounting opening
40 for mounting a bleeder plug 39 for release of air is vertically
formed at an upper end position above the pipe mount opening 38. In
addition, the outer-side cylinder portion 20 and the inner-side
cylinder portion 21 of the caliper body 16 include pad pin holes 41
for mounting of the pad pins 30. The pad pin holes 41 extend in an
axial direction of the disc.
[0048] In this embodiment, the outer-side cylinder portion 20, the
inner-side cylinder portion 21, all the outer-side torque bearing
portions 23, all the inner-side torque bearing portions 24 and all
the disc pass portions 26 are cast into a one-piece member, which
forms the caliper body 16.
[0049] For casting, a core 44 shown in FIGS. 4 to 6 is used. In
this embodiment, as the core 44, use is made of a shell core of
resin-coated sand (quartz sand) consolidated by means of heat. The
core 44 comprises a base portion 45, a plurality (two in this
embodiment) of pad-mounting space forming portions 46 extending
from the base portion 45 in the same direction while being spaced
from each other, and a plurality (four in this embodiment) of
prepared hole forming portions 47 extending in opposite directions
beyond the pad-mounting space forming portions 46 so as to
orthogonally intersect the direction of array of the pad-mounting
space forming portions 46. Each prepared hole forming portion 47
comprises an inner-diameter prepared hole forming portion 49 having
a solid cylindrical body and an inmost recess forming portion 50 in
a disc-like form, the inmost recess forming portion being formed in
the inner-diameter prepared hole forming portion 49 on a side
opposite to the pad-mounting space forming portion 46 in a coaxial
relationship to the inner-diameter prepared hole forming portion
49. The inmost recess forming portion 50 has a larger diameter than
the inner-diameter prepared hole forming portion 49 and also has a
larger diameter than the inner-diameter portion 32 of the bore 31
after machining of an inner surface of a prepared hole.
[0050] The core 44 comprises communication passage forming portions
51, each connecting proximately opposed portions of the adjacent
inmost recess forming portions 50 arranged on the same side of the
core 44, recess forming portions 52 extending from the inmost
recess forming portions 50 disposed on opposite sides of one
pad-mounting space forming portion 46. Each recess forming portion
52 extends from the corresponding inmost recess forming portion 50
on a side opposite to the communication passage forming portion 51
outwardly as viewed in a radial direction of the inmost recess
forming portion 50. The recess forming portion 52 has a
substantially tapered triangular form projecting from the inmost
recess forming portion 50 while being inclined relative to the
radial direction of the prepared hole forming portion 47, and has a
non-circular form. In other words, the recess forming portion 52 is
configured, such that it does not extend along the circumference of
the inmost recess forming portion 50 in a coaxial relationship to
the inmost recess forming portion 50, but extends outwardly from a
circumferential part of the inmost recess forming portion 50. A
projection forming portion 53 in the form of a recess is formed at
a central portion of a surface of the inmost recess forming portion
50 on a side opposite to the inner-diameter prepared hole forming
portion 49.
[0051] The core 44 is provided in a mold 55 indicated by a two-dot
chain line in FIG. 4. Then, for example, an aluminum alloy in
molten state is charged into a cavity 56 formed by the mold 55 and
the core 44. In the cavity 56, the pad-mounting space forming
portions 46 are fully spaced apart from each other. After charging,
the mold is disassembled, and the core 44 is removed. As a result,
a caliper body casting 16A shown in FIGS. 7 to 15 is obtained.
[0052] In the casting 16A of the caliper body 16, as shown in FIGS.
7, 9 and 10, the outer-side cylinder portion 20 and the inner-side
cylinder portion 21 facing each other are formed by means of the
mold 55 and the two pad-mounting space forming portions 46 of the
core 44. The three outer-side torque bearing portions 23
respectively project from the outer-side cylinder portion 20
towards the inner side of the disc while being spaced from each
other in a direction of rotation of the disc. The three inner-side
torque bearing portions 24 respectively project from the inner-side
cylinder portion 21 towards the outer side of the disc while being
spaced from each other in a direction of rotation of the disc. The
three disc pass portions 26 are formed, each of which connects
outer sides (In a radial direction of the disc) of the outer-side
torque bearing portion 23 and the inner-side torque bearing portion
24 arranged in an axial direction of the disc. At this time, the
casting 16A also includes three interpositions 58 each connecting,
on an inner side of the disc pass portion 26 (as viewed in a radial
direction of the disc), the outer-side torque bearing portion 23
and the inner-side torque bearing portion 24 arranged in an axial
direction of the disc, and thus the two pad-mounting spaces 28 are
formed at two positions between the outer-side cylinder portion 20
and the inner-side cylinder portion 21. As indicated in FIG. 11,
the disc pass portion 26 and the interposition 58 corresponding to
each other in terms of a position in a direction of rotation of the
disc are formed as one piece in a radial direction of the disc. As
indicated in FIGS. 13 to 15, a surface 58A of the interposition 58
on an inner side thereof in a radial direction of the disc, and a
surface 23A of the outer-side torque bearing portion 23 and a
surface 24A of the inner-side torque bearing portion 24, are
connected without being stepped.
[0053] The two pad-mounting spaces 28 are formed by means of two
pad-mounting space forming portions 46 of the core 44. As shown in
FIGS. 10 and 11, the outer-side cylinder portion 20 of the casting
16A of the caliper body 16 includes prepared holes 31A, which are
formed by means of the prepared hole forming portions 47 projecting
from the pad-mounting space forming portions 46 of the core 44.
Specifically, two prepared holes 31A are formed, each of which is
formed between the adjacent outer-side torque bearing portions 23
of the outer-side cylinder portion 20. Each of the prepared holes
31A is formed in a surface 20A facing the inner-side cylinder
portion 21, so as to have a predetermined depth.
[0054] That is, in the outer-side cylinder portion 20, an
inner-diameter prepared hole portion 32A of the prepared hole 31A
having a cylindrical surface is formed by means of the
inner-diameter prepared hole forming portion 49 of the core 44.
Further, by means of the inmost recess forming portion 50 of the
core 44, an inmost recess portion 60 of the prepared hole 31A,
which has a larger diameter than the inner-diameter prepared hole
portion 32A and also has a larger diameter than the inner-diameter
portion 32 of the bore 31 after machining, is formed at an end of
the inner-diameter prepared hole portion 32A on a side of a bottom
portion 61 in a coaxial relationship with the inner-diameter
prepared hole portion 32A.
[0055] Further, in the outer-side cylinder portion 20, a bottom
surface 59 forming the inmost recess portion 60 of each prepared
hole 31A includes a projection 64 slightly projecting therefrom in
an axial direction. The projection 64 is formed by means of the
projection forming portion 53 of the core 44 during casting.
[0056] Further, in the outer-side cylinder portion 20, proximately
opposed portions of the inmost recess portions 60 disposed adjacent
to each other in a direction of rotation of the disc are
communicated with each other through a communication passage 62,
which is formed by means of the communication passage forming
portion 51 of the core 44 during casting. As shown in FIG. 12, a
recess 63 is formed at the inmost recess portion 60 (i.e., the
bottom portion 61 of the prepared hole 31A) on the exit side of the
disc during braking when the vehicle travels in a forward
direction. The recess 63 is located on a side opposite to the
communication passage 62 relative to the inmost recess portion 60.
The recess 63 is formed by means of the recess forming portion 52
of the core 44, and has a non-circular form. Specifically, the
recess 63 has a substantially tapered triangular form extending
outwardly in a radial direction of the prepared hole 31A while
being inclined relative to the radial direction of the prepared
hole 31A. The recess 63 extends from the inmost recess portion 60
outwardly in a radial direction of the disc. In other words, a
distal end of the recess is located outwardly from a region
occupied by the corresponding inmost recess portion as viewed in a
direction of rotation of the disc, while being located radially
outwardly from the center axis of the corresponding bore as viewed
in a radial direction of the disc. Further, a proximal end of the
recess 63, which is located on a side of the inmost recess portion
60, extends to a position corresponding to the center axis of the
prepared hole 31A or a position located inwardly from the center
axis of the prepared hole 31A as viewed in the radial direction of
the disc 12. By this arrangement, air is prevented from being
accumulated between the inmost recess portion 60 and the proximal
end of the recess 63. Specifically, the proximal end of the recess
extends, outwardly in a radial direction of the disc along the
circumference of the inmost recess portion, from a position
corresponding to the center axis of the corresponding bore or a
position located inwardly from the center axis of the corresponding
bore as viewed in a radial direction of the disc. By this
arrangement, when the caliper body 16 is mounted in vertical
position as shown in FIG. 1, with the recess 63 being located at
the top of the inmost recess portion, it is possible to avoid air
being trapped in an uppermost portion of a circumferential wall
surface of the inmost recess portion.
[0057] Similarly, the inner-side cylinder portion 21 of the casting
16A of the caliper body 16 includes prepared holes 31A, which are
formed by means of the prepared hole forming portions 47 projecting
from the pad-mounting space forming portions 46 of the core 44.
Specifically, two prepared holes 31A are formed, each of which is
formed between the adjacent inner-side torque bearing portions 24
of the inner-side cylinder portion 21. Each of the prepared holes
31A is formed in a surface 21A facing the outer-side cylinder
portion 20 so as to have a predetermined depth.
[0058] That is, in the inner-side cylinder portion 21, the
inner-diameter prepared hole portion 32A of the prepared hole 31A
having a cylindrical surface is formed by means of the
inner-diameter prepared hole forming portion 49 of the core 44.
Further, by means of the inmost recess forming portion 50 of the
core 44, the inmost recess portion 60, which has a larger diameter
than the inner-diameter prepared hole portion 32A and also has a
larger diameter than the inner-diameter portion 32 of the bore 31
after machining, is formed at an end of the inner-diameter prepared
hole portion 32A on a side of the bottom portion 61 in a coaxial
relationship with the inner-diameter prepared hole portion 32A.
[0059] In the inner-side cylinder portion 21, the bottom surface 59
forming the inmost recess portion 60 of each prepared hole 31A
includes the projection 64 slightly projecting therefrom in an
axial direction. The projection 64 is formed by means of the
projection forming portion 53 of the core 44 during casting.
[0060] Further, in the inner-side cylinder portion 21, proximately
opposed portions of the inmost recess portions 60 disposed adjacent
to each other in the direction of rotation of the disc are
communicated with each other through the communication passage 62,
which is formed by means of the communication passage forming
portion 51 of the core 44 during casting. By means of the recess
forming portion 52 of the core 44, the recess 63 is formed at the
inmost recess portion 60 on the exit side of the disc during
braking when the vehicle travels in a forward direction. The recess
63 is located on a side opposite to the communication passage 62
relative to the inmost recess portion 60. The recess 63 has a
non-circular form. Specifically, the recess 63 has a substantially
tapered triangular form extending from the inmost recess portion 60
outwardly in a radial direction of the prepared hole 31A. The
proximal end of the recess 63, which is located on a side of the
inmost recess portion 60, extends to a position corresponding to
the center axis of the prepared hole 31A or a position located
inwardly from the center axis of the prepared hole 31A as viewed in
the radial direction of the disc 12. By this arrangement, air is
prevented from being accumulated between the inmost recess portion
60 and the proximal end of the recess 63.
[0061] The recess 63 of the outer-side cylinder portion 20 and the
recess 63 of the inner-side cylinder portion 21 correspond to each
other in terms of a position in the direction of rotation and in
the radial direction of the disc.
[0062] Thus, in the casting 16A of the caliper body 16, prepared
holes 31A, which are machined into the bores 31, are arranged at a
plurality (two in this embodiment) of positions in a spaced
relationship in the direction of rotation of the disc 12. The
inner-side torque bearing portion 24, the outer-side torque bearing
portion 23, the disc pass portion 26 and the interposition 58 are
formed as a one-piece member by casting between the prepared holes
31A adjacent to each other in the direction of rotation of the
disc.
[0063] Further, in the casting 16A of the caliper body 16, the
recess 63 is formed at a position corresponding to the top of the
uppermost prepared hole 31A (the prepared hole 31A located on the
exit side of the disc during braking when the vehicle travels in a
forward direction) when the caliper body is mounted on the vehicle
body.
[0064] When the bores 31 are formed at three or more positions in a
spaced relationship in the direction of rotation of the disc, the
number of the pad-mounting spaces 28 and the number of the prepared
holes 31A facing the pad-mounting spaces 28 are increased according
to the number of bores 31, and the communication passage 62 is
provided at each of the positions between the prepared holes 31A
arranged in the direction of rotation of the disc. In this case,
the inner-side torque bearing portion 24, the outer-side torque
bearing portion 23, the disc pass portion 26 and the interposition
58, which are formed into one piece by casting, are also provided
at each of the positions between the prepared holes 31A arranged in
a direction of rotation of the disc. In this case, the recess 63 is
formed at the inmost recess portion 60 on a side opposite to the
communication passage 62, the inmost recess portion 60 being
located most closely to the exit side of the disc during braking
when the vehicle travels in a forward direction and also located at
an uppermost position when the caliper body is mounted.
[0065] The casting 16A is machined in a manner such as mentioned
below, to thereby obtain the caliper body 16 shown in FIGS. 16 to
26.
[0066] An outer surface 20B of the outer-side cylinder portion 20
on a side opposite to the disc 12 and an outer surface 21B of the
inner-side cylinder portion 21 on a side opposite to the disc 12
are clamped by means of a machining apparatus. In this instance,
the interposition 58 formed on an inner side of the disc pass
portion 26 in a radial direction of the disc 12 makes an
intermediate portion between the outer-side torque bearing portion
23 and the inner-side torque bearing portion 24 have the same wall
thickness as the outer-side torque bearing portion 23 and the
inner-side torque bearing portion 24 in a radial direction of the
disc 12. Further, the outer-side torque bearing portion 23, the
inner-side torque bearing portion 24, the disc pass portion 26 and
the interposition 58 are provided between the prepared holes 31A
adjacent to each other in a direction of rotation of the disc, in
addition to those provided on opposite ends of the outer-side
cylinder portion 20 and the inner-side cylinder portion 21 in a
direction of rotation of the disc. Therefore, deformation of the
casting 16A due to application of clamping force can be
prevented.
[0067] Then, a tool is inserted from each pad-mounting space 28
between the outer-side cylinder portion 20 and the inner-side
cylinder portion 21 into the casting 16A clamped by the machining
apparatus. Then, as shown in FIGS. 19 and 21, a cutting operation
is conducted with respect to only the inner-diameter prepared hole
portion 32A of the prepared hole 31A formed in each of the
outer-side cylinder portion 20 and the inner-side cylinder portion
21 and facing the pad-mounting space 28, and the inner-diameter
prepared hole portion 32A is formed into the inner-diameter portion
32 by boring (see the inner-diameter prepared hole portion 32A
before boring and the inner-diameter portion 32 obtained after
boring shown in FIG. 26). Two seal grooves 66 and 67 are also
formed in the inner-diameter portion 32 by a milling operation.
Thus, each of the bores 31 formed comprises the inner-diameter
portion 32 and the seal grooves 66 and 67, which are formed by
machining, and the inmost recess portion 60 which is unmachined
after casting. For assembly, the piston 17 is fitted into the
inner-diameter portion 32 of each bore 31, with seal rings (not
shown) being fittingly disposed in the seal grooves 66 and 67.
Thus, each of the bores 31 is formed by machining from a portion on
a side of the pad-mounting space 28 between the inner-side cylinder
portion 21 and the outer-side cylinder portion 20. Therefore, the
bottom portions 61 of all the bores 31 are maintained in a closed
state obtained by casting. The projection 64 of the inmost recess
portion 60 enables the piston 17 and the bottom surface 59 to be
always spaced apart from each other, even when the piston 17 abuts
against the projection 64.
[0068] Further, a tool is inserted from each pad-mounting space 28
between the outer-side cylinder portion 20 and the inner-side
cylinder portion 21 and the surfaces of the outer-side torque
bearing portion 23 and the surfaces of the inner-side torque
bearing portion 24 facing the pad-mounting space 28 are cut by
milling, to thereby form outer-side torque bearing surfaces 70 and
inner-side torque bearing surfaces 71 shown in FIGS. 16, 18, 19 and
21. The outer-side torque bearing surfaces 70 and inner-side torque
bearing surfaces 71 are adapted to abut against the end surfaces of
the pads 33 in a direction of rotation of the disc 12, to thereby
receive a torque from the pads 33.
[0069] Then, a tool is inserted from each pad-mounting space 28
between the outer-side cylinder portion 20 and the inner-side
cylinder portion 21, and the outer-side surface 20a and the
inner-side surface 21a facing each other are formed by milling.
[0070] The mounting bolt openings 37 shown in FIGS. 16 and 18 to 20
for insertion of mounting bolts into the mount portion 14 of the
front fork 13 are formed by boring in the outer-side cylinder
portion 20 at two positions spaced apart from each other in a
direction of rotation of the disc 12. The mounting bolt openings 37
orthogonally intersect an axial direction of the disc and extend
through the outer-side cylinder portion 20 in parallel to each
other. The pad pin holes 41 extending in an axial direction of the
disc 12 are also formed by boring.
[0071] Further, as shown in FIGS. 20 and 22, a linear passage
opening 75, with the bleeder mounting opening 40 for mounting the
bleeder plug 39 being formed at an open end portion thereof, is
formed by boring from an external surface of the outer-side
cylinder portion 20 as viewed in a direction of rotation of the
disc 12 so as to extend towards the top of the recess 63 of the
outer-side cylinder portion 20. The bleeder mounting opening 40 is
threaded. Since the bleeder mounting opening 40 is disposed at an
upper position when the caliper body is mounted on a vehicle body,
the passage opening 75 is formed by cutting from the external
surface of a portion of the outer-side cylinder portion 20 that is
located at an upper position when the caliper body is mounted on a
vehicle body, and is communicated with the recess 63.
[0072] Further, a linear communication opening 76, with the pipe
mount opening 38 for mounting a brake pipe from a master cylinder
being formed at an open end portion thereof, is formed by boring
from an external surface of the outer-side cylinder portion 20 as
viewed in an axial direction of the disc 12 so as to extend towards
an intermediate position in the caliper body 16. An intermediate
part of the communication opening 76 intersects the passage opening
75 having the bleeder mounting opening 40. The pipe mount opening
38 is threaded. Further, a connection opening (passage opening) 77
is formed by boring from an external surface of the inner-side
cylinder portion 21 as viewed in an axial direction of the disc 12
so as to extend towards the intermediate position in the caliper
body 16. The connection opening 77 extends through the recess 63 of
the inner-side cylinder portion 21 and intersects the communication
opening 76. To close an open end of the connection opening 77
exposed at the external surface of the inner-side cylinder portion
21, a ball is struck into the open end of the connection opening 77
during assembly.
[0073] As described above, the adjacent inmost recess portions 60,
that is, the bores 31, of the outer-side cylinder portion 20
arranged in a direction of rotation of the disc 12 are communicated
with each other through the communication passage 62. The adjacent
inmost recess portions 60, that is, the bores 31, of the inner-side
cylinder portion 21 are also communicated with each other through
the communication passage 62. The inmost recess portion 60 (that
is, the bore 31) having the recess 63 in the outer-side cylinder
portion 20 is communicated through this recess 63, the passage
opening 75, the communication opening 76 and the connection opening
77 with the inmost recess portion 60 (that is, the bore 31) having
the recess 63 in the inner-side cylinder portion 21. Thus, all the
bores 31, i.e., the bores 31 arranged in a direction of rotation of
the disc 12, and the bores 31 disposed in a face-to-face
relationship in an axial direction of the disc 12 with the bores 31
arranged in the direction of rotation of the disc 12, are
communicated with each other, and disposed in a single brake fluid
flow passage. The communication opening 76 having the pipe mount
opening 38, and the passage opening 75 and the connection opening
77, each intersecting the communication opening 76, form a
connection passage 80 for communication between the bores 31
disposed on opposite sides of the disc 12 in an axial direction of
the 12. Therefore, the communication opening 76 forms a part of the
connection passage 80.
[0074] Thus, all the bores 31 are communicated with the pipe mount
opening 38 formed at the open end portion of the communication
opening 76. Therefore, brake fluid is introduced into the bores 31
through a brake pipe which is connected to the communication
opening 76 during assembly. Further, all the bores 31 are
communicated with the bleeder mounting opening 40 formed at the
open end portion of the passage opening 75. Therefore, release of
air is conducted through the bleeder plug 39, which is connected to
the bleeder mounting opening 40 during assembly.
[0075] Then, other necessary machining operations are conducted and
finally, all the interpositions 58, which are formed by casting on
an inner side (as viewed in a radial direction of the disc) of the
disc pass portions 26 between the outer-side torque bearing
portions 23 and the inner-side torque bearing portions 24, are
removed by milling, to thereby form pass recesses 34 for the disc
12 on an inner side (as viewed in a radial direction of the disc)
of the disc pass portions 26 between the outer-side torque bearing
portions 23 and the inner-side torque bearing portions 24, as shown
in FIGS. 18, 19, 21 and 23 to 25. Thus, the disc pass portions 26
are formed between the outer-side torque bearing portions 23 and
the inner-side torque bearing portions 24. Each disc pass portion
26 connects outer sides (as viewed in a radial direction of the
disc) of the outer-side torque bearing portion 23 and the
inner-side torque bearing portion 24, and has a smaller
wall-thickness than the outer-side torque bearing portion 23 and
the inner-side torque bearing portion 24.
[0076] The order of machining operations is not limited to the
above embodiment and may be appropriately changed.
[0077] In the above embodiment, in the caliper body 16, the
prepared hole 31A for the bore 31 into which the piston 17 is
slidably fitted and the recess 63 extending from the bottom portion
61 of the prepared hole 31A outwardly in a radial direction of the
prepared hole 31A are formed by means of the core 44 during
casting. Therefore, an open end of the recess 63 which connects to
the bore 31 can be formed with high precision. The linear passage
opening 75 and the connection opening 77 are formed by cutting from
an exterior surface of the caliper body 16 so as to extend to the
recesses 63 which are formed with high precision relative to the
bores 31. Therefore, it is not required to form the passage opening
75 and the connection opening 77 with high machining accuracy,
resulting in ease of forming operations and high production
efficiency. Further, it is unnecessary to form the passage opening
75 and the connection opening 77 while avoiding interference with
an opening for mounting a separate bottom portion of the bore.
Therefore, the positions of the passage opening 75 and the
connection opening 77 can be determined with a high degree of
freedom of design.
[0078] Of a plurality of bores 31 formed in a spaced relationship
in a direction of rotation of the disc, the adjacent bores 31 are
communicated with each other through the communication passage 62
which is formed during casting. The recess 63 is formed at a
position corresponding to the top of the uppermost bore 31 when the
caliper body is mounted on a vehicle body. The linear passage
opening 75 for communication with the recess 63 is formed by
cutting from an external surface of the caliper body 16 at a
position on an upper side when the caliper body is mounted on a
vehicle body. Therefore, release of air can be satisfactorily
conducted through the communication passage 62, the recess 63 and
the passage opening 75.
[0079] The plurality of bores 31 formed in a spaced relationship in
a direction of rotation of the disc are communicated with each
other through the communication passage 62, the recess 63 and the
passage opening 75. Further, a part of the connection passage 80
for communication between the bores 31 disposed on opposite sides
in an axial direction of the disc 12 is formed by the communication
opening 76 which is formed by cutting from an exterior surface so
as to intersect the passage opening 75. Therefore, it is possible
to reduce the number of openings for communication between all the
bores 31 arranged in a direction of rotation of the disc and
arranged in an axial direction of the disc.
[0080] FIGS. 27 and 28 show a second embodiment of the present
invention. In these drawings, elements corresponding to those in
the first embodiment are designated by the corresponding reference
numerals prefixed with 1. The constructions and effects of those
elements are the same as those in the first embodiment, unless
otherwise described.
[0081] In a caliper body 116 in the second embodiment, a pipe mount
opening 138 is formed between two bores 131 of an outer-side
cylinder portion 120. In the first embodiment, as shown in FIG. 20,
a portion between the mounting bolt opening 37 and an adjacent
exterior surface of the outer-side cylinder portion 20 is required
to have a sufficiently large wall thickness for accommodating the
pipe mount opening 38 and the communication opening 76 extending
therefrom. In the second embodiment in which the pipe mount opening
138 is formed between the two bores 131, there is no need to
provide such a portion having a large wall thickness. This achieves
a reduction in weight of the caliper body.
[0082] Further, as is apparent from FIG. 27, by utilizing recesses
163 extending outwardly from the bottom portions of the bores 131,
the recesses 163 on opposite sides of the caliper body 116 are
communicated with each other through two passage openings 175 and
175a intersecting each other, and also communicated with a bleeder
mounting opening 140. An outer end of the passage opening 175a is
to be closed in the same manner as in the first embodiment. Thus,
in the second embodiment, the same effects as those of the first
embodiment can be obtained by using two linear passage openings,
and therefore an operation for forming passage openings becomes
easy. This is because the recesses 163 increases the freedom of
design regarding the location of passage openings, and enable the
linear passage opening 175a to pass through the wall between a
pad-mounting space 128 and the mounting bolt opening 137 disposed
adjacent to the recess 163.
[0083] In the second embodiment, a proximal end of the recess 163
extends along the circumference of the corresponding bore 131 to a
position that is located inwardly from the center axis of the bore
as viewed in a radial direction of the disc. This arrangement has
the same effect as the first embodiment. That is, when the caliper
body 116 is mounted in a vertical position with the recess 163
being located at the top of the corresponding bore 131, it is
possible to more effectively prevent air from being trapped in the
uppermost portion of the circumferential wall surface of the
bore.
[0084] The position to which the proximal end of the recess 163
extends along the circumference of the bore 131 may be defined in a
different way as well. The position may be located on a gravity
line that is drawn from the center axis of the bore in a direction
parallel to the direction of gravity when the caliper body 116 is
mounted on a vehicle, wherein the intersection of the gravity line
and the circumference of the bore near an inner end of the linear
passage opening 175a communicating with the recess 163 is closer to
the center of the disc than an intersection of a radius line drawn
from the center of the bore to the inner end of the linear passage
opening 175a and the circumference. In other words, the caliper is
mounted on the vehicle substantially vertically as shown
schematically in FIGS. 1 and 2. The position may also be located on
the same side of the gravity line as the center of the disc.
* * * * *