U.S. patent application number 14/153423 was filed with the patent office on 2014-07-10 for method for retaining member by caulking.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Taro FURUKUBO, Takeshi ISHIDA.
Application Number | 20140190012 14/153423 |
Document ID | / |
Family ID | 42730942 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140190012 |
Kind Code |
A1 |
ISHIDA; Takeshi ; et
al. |
July 10, 2014 |
METHOD FOR RETAINING MEMBER BY CAULKING
Abstract
During a caulking process, a pressure is applied to a pressure
receiving shoulder portion in the same direction as a direction of
a clamping force generated by a caulking portion. The clamping
force for holding an outer race can thereby be increased. Also, a
pressure receiving surface of the pressure receiving shoulder
portion is set higher than an end face. Thus, no pressure resulting
from plastic deformation in a direction perpendicular to the
direction of the clamping force of the caulking portion is
generated. In addition, a groove is formed between the pressure
receiving shoulder portion and an end serving as the caulking
portion.
Inventors: |
ISHIDA; Takeshi; (Aichi-ken,
JP) ; FURUKUBO; Taro; (Nagoya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Aichi-ken |
|
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Aichi-ken
JP
|
Family ID: |
42730942 |
Appl. No.: |
14/153423 |
Filed: |
January 13, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12697489 |
Feb 1, 2010 |
8668620 |
|
|
14153423 |
|
|
|
|
Current U.S.
Class: |
29/898.042 ;
29/505 |
Current CPC
Class: |
F01L 13/0015 20130101;
B21K 25/00 20130101; Y10T 74/18568 20150115; F16C 19/184 20130101;
Y10T 74/18576 20150115; Y10T 428/24479 20150115; Y10T 29/49908
20150115; Y10T 29/49647 20150115; B21D 39/04 20130101; Y10T 428/13
20150115; F01L 2820/032 20130101; F16C 2361/61 20130101; B21J 9/025
20130101; B23P 15/003 20130101; F16C 35/067 20130101; Y10T 156/1002
20150115; F16H 25/20 20130101 |
Class at
Publication: |
29/898.042 ;
29/505 |
International
Class: |
B23P 15/00 20060101
B23P015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2009 |
JP |
2009-061488 |
Claims
1. A method for retaining a member by caulking, comprising: bending
an end of a workpiece along a corner portion of the member by a
caulking surface of a caulking roller; applying a pressure to a
pressure receiving shoulder portion, which is formed coaxially on
the outside of a bent side of the end of the workpiece, in a same
direction as a caulking pressure applied to the caulking surface so
that a caulking process is performed to form a caulked portion, and
the member is held along a base of the workpiece by a clamping
force of the caulked portion; and setting a timing for starting a
caulking end process to a timing when a caulking load applied to
the caulking roller during the caulking process or a caulking
torque for rolling the caulking roller undergoes a specific change
indicating that the member begins to be strained.
2. The method according to claim 1, wherein the workpiece is a
caulked retaining member that includes a groove between the bent
side and the pressure receiving shoulder portion.
3. The method according to claim 1, wherein the caulking roller
applies the pressure to the pressure receiving shoulder
portion.
4. The method according to claim 1, wherein the specific change
indicating that the member begins to be strained is an abrupt
increase in the caulking load.
5. The method according to claim 1, wherein the specific change
indicating that the member begins to be strained is an abrupt
decrease in the caulking torque.
6. The method according to claim 1, wherein: the member is a
bearing; and the workpiece is a housing that accommodates a rotary
member rotatably supported by the bearing, or a bearing holder
arranged in the housing.
7. The method according to claim 6, wherein: the bearing and the
housing or the bearing holder are a bearing and a housing or a
bearing holder in a rotation-translation conversion actuator
respectively; and the housing is mounted to a driven object device,
the rotation-translation conversion actuator also includes an
output shaft, which moves in an axial direction of the workpiece
through rotation of the rotary member, and protrudes outward from
the housing to transmit a driving force from the output shaft to
the driven object device.
8. The method according to claim 7, wherein: the rotary member is a
nut of a planetary differential screw type rotation-translation
converter; the output shaft is a sun shaft; a planetary shaft is
arranged between the nut and the sun shaft; and the sun shaft and
the planetary shaft mesh with the nut in a manner to perform
rotation-translation conversion.
9. The method according to claim 7, wherein the driven object
device is an internal combustion engine.
10. The method according to claim 3, wherein the caulking surface
formed on the caulking roller and a pressing surface for applying
the pressure to the pressure receiving shoulder portion are formed
as a stepless cylindrical surface.
Description
INCORPORATION BY REFERENCE
[0001] This is a divisional application of U.S. patent application
Ser. No. 12/697,489, filed on Feb. 1, 2010, claiming priority based
on Japanese Patent Application No. 2009-061488 filed on Mar. 13,
2009, the disclosures of which, including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a caulked retaining member, one end
of which is bent through a calking process to form a caulked
portion, that holds a member along a base of the caulked retaining
member through the clamping force of the caulked portion, a method
for retaining a member by caulking, a structure of a caulked
retaining member, and a caulking apparatus for a caulking
process.
[0004] 2. Description of the Related Art
[0005] There is known a rotation-translation conversion actuator
that is mounted in an internal combustion engine or the like to
apply a translational driving force to the engine (e.g., see
Japanese Patent Application Publication No. 2007-303408
(JP-A-2007-303408) and Japanese Patent Application Publication No.
2007-303479 (JP-A-2007-303479)). The publications, JP-A-2007-303408
and JP-A-2007-303479 each describe a rotation-translation
conversion actuator that drives a valve lift device of an internal
combustion engine. A rotary body is rotatably supported in the main
body case of the rotation-translation conversion actuator via a
bearing. The rotary body is rotationally driven by a motor. Thus, a
screw shaft makes a translational movement in an axial direction to
drive the valve lift device.
[0006] In JP-A-2007-303408 and JP-A-2007-303479, an annular support
member is arranged inside the housing and bolted to an inner
surface of the housing to fix the bearing for rotatably supporting
the rotary body in the housing.
[0007] However, due to the configuration in which the annular
support member is arranged inside the housing and fastened by the
bolt to fix the bearing as described above, the housing tends to be
large. In order to prevent the housing from increasing in size, a
method of supporting the bearing through a caulking process instead
of using the annular support member or bolting the annular support
member.
[0008] However, if the housing is simply caulked and the bearing is
clamped in the housing in the case where a member requiring a
certain clamping force, such as the bearing or the like, is held by
the housing, the residual axial force of the housing as a force
serving to generate the clamping force cannot be sufficiently
increased. As a result, the clamping force for holding the bearing
may become insufficient. In order to increase the residual axial
force, it is conceivable to apply a pressure to a base of a work in
the same direction as the direction of the clamping force apart
from a position where the work is bent through the caulking
process.
[0009] However, in the caulking process for the bearing as
described above, the rotational resistance of the bearing needs to
be held small. For this purpose, the application of the pressure
for increasing the residual axial force needs to be prevented from
increasing in the radial strain of the bearing.
[0010] As a caulking process for other purposes, there are known an
art in which the inflexion point of a change rate of a pressure
exerted by an electric press is set as a completion point of the
press operation (see Japanese Patent Application Publication No.
2001-162396 (JP-A-2001-162396)) and an art in which an inflexion
point corresponding to a decrease in the caulking load of a
caulking punch is detected based on the relationship between the
caulking load and a caulking stroke of the caulking punch to
control the amount of a material with which a groove is filled (see
Japanese Patent Application Publication No. 2002-35864
(JP-A-2002-35864)).
[0011] In addition, conventionally a groove is formed between a
caulking portion of a workpiece and a contour region of the
workpiece to prevent a caulking process from affecting the contour
of the work (see Japanese Patent Application Publication No.
2005-34857 (JP-A-2005-34857)). Further, there are known an art in
which a load is applied to a bearing side to increase the clamping
force resulting from caulking (see Japanese Patent Application
Publication No. 2008-223840 (JP-A-2008-223840)), and an art in
which a spherical bearing is fixed to a housing by tumbling one of
both sides separated from each other by a V-shaped groove (see
Japanese Patent Application Publication No. 2002-21867
(JP-A-2002-21867)).
[0012] If a configuration is adopted in which a held member, such
as a bearing or the like, is held by a caulked portion by applying
pressure to the base of a workpiece in the same direction as the
direction of a clamping force without applying pressure to the
caulking portion, it is conceivable to further combine with this
caulking process the method in which the inflexion point of the
pressurization force is set as the completion point of the press
operation as described in JP-A-2001-162396. However, even if this
method is combined with the caulking process, it is unclear whether
the member such as the bearing or the like may be restrained from
being radially strained as the method described in JP-A-2001-162396
is put into practice in the caulking process.
[0013] This also holds true where the art of the caulking punch
described in JP-A-2002-35864 is applied. It is unclear whether the
member such as the bearing or the like is restrained from being
radially strained through the caulking punching.
[0014] Furthermore, in JP-A-2005-34857, JP-A-2008-223840, and
JP-A-2002-21867, when caulking part of the workpiece onto the
member such as the bearing or the like, no consideration is given
to the idea of restraining the member from being radially
strained.
SUMMARY OF THE INVENTION
[0015] The invention restrains a member from being radially
strained through application of a pressure to a base of a caulked
retaining member in the same direction as the direction of a
clamping force apart from the caulking portion in a configuration
in which a held member is held by a caulked portion.
[0016] A first aspect of the invention relates to caulked retaining
member that is bent at one end through a caulking process to form a
caulked portion and holds a member along a base of the caulked
retaining member by a clamping force of the caulked portion. In the
caulked retaining member, the base has a pressure receiving
shoulder portion, which receives a pressure in a same direction as
a direction of the clamping force, and is formed coaxially on the
outside of a bent side of the end, and a groove is formed between
the end and the pressure receiving shoulder portion.
[0017] By using the caulked retaining member that includes the
pressure receiving shoulder portion formed on the base thereof, the
pressure can be applied with the aid of the pressure receiving
shoulder portion during the caulking process of the end. Also, the
groove is formed between the pressure receiving shoulder portion to
which the pressure is thus applied and the end serving as the
caulked portion.
[0018] Thus, during the caulking process to bend the end, even when
the pressure is applied to the pressure receiving shoulder portion
simultaneously and causes deformation, especially plastic
deformation, the groove absorbs plastic flow. In this case, the
groove especially absorbs plastic flow from a member on the
pressure receiving shoulder portion side to a member on the end
side, that is, plastic flow toward the member. Accordingly, the
caulked portion side can be prevented from being radially strained
in accordance with deformation of the pressure receiving shoulder
portion after the caulking process.
[0019] Thus, in the construction in which the held member is held
by the caulked portion by applying the pressure to the base of the
caulked retaining member in the same direction as the direction of
the clamping force apart from the caulked portion, the member can
be restrained from being radially strained through application of
the pressure.
[0020] A second aspect of the invention relates to a caulked
retaining member that has an end thereof bent through a caulking
process to form a caulked portion and holds a member along a base
of the caulked retaining member by a clamping force of this caulked
portion. In this caulked retaining member, the base has a pressure
receiving shoulder portion, which receives a pressure in a same
direction as a direction of the clamping force, and is formed
coaxially on the outside of a bent side of the end, and the
pressure receiving shoulder portion has a pressure receiving
surface set at such a position that no pressure is applied to the
member as a result of plastic deformation of the caulked portion in
a direction perpendicular to a direction of the clamping force.
[0021] By using the caulked retaining member having the pressure
receiving shoulder portion formed on the base thereof as in the
case of the foregoing first aspect of the invention, the pressure
can be applied with the aid of the pressure receiving shoulder
portion during the caulking process of the end. According to the
second aspect of the invention, the pressure receiving surface of
the pressure receiving shoulder portion is set at such a position
that no pressure is applied to the member as a result of plastic
deformation of the caulked portion in the direction perpendicular
to the direction of the clamping force.
[0022] Thus, during the caulking process to bend the end, even when
the pressure is applied to the pressure receiving shoulder portion
simultaneously and causes plastic deformation, this plastic
deformation allows no pressure to be applied to the member in the
direction perpendicular to the direction of the clamping force.
Thus, the caulked portion side can be prevented from being radially
strained in accordance with deformation of the pressure receiving
shoulder portion after the caulking process.
[0023] Thus, in the construction in which the member is held by the
caulked portion by applying the pressure to the base of the work in
the same direction as the direction of the clamping force apart
from the caulking portion, the held member can be restrained from
being radially strained through application of the pressure.
[0024] A third aspect of the invention relates to a method for
retaining a member by caulking. This method includes bending an end
of a caulked retaining member along a corner portion of the member
by a caulking surface of a caulking roller and the member is held
along a base of the work by a clamping force of this caulking
portion, and applying a pressure to the pressure receiving shoulder
portion in the same direction as the direction of the clamping
force during this caulking process.
[0025] According to the foregoing aspect of the invention, even
when plastic deformation results from the pressure applied to the
pressure receiving shoulder portion in the same direction as the
direction of the clamping force through the caulking process of the
above-described caulked retaining member by the caulking roller
during this caulking process, the caulked portion side can be
prevented from being radially strained in accordance with
deformation of the pressure receiving shoulder portion after the
caulking process, and the member can be restrained from being
radially strained.
[0026] A fourth aspect of the invention relates to a method for
retaining a member by caulking. The method includes: bending an end
of a workpiece along a corner portion of the member by a caulking
surface of a caulking roller; applying a pressure to a pressure
receiving shoulder portion, which is formed coaxially on the
outside of a bent side of the end of the workpiece, in a same
direction as a caulking pressure applied to the caulking surface so
that a caulking process is performed to form a caulked portion, and
the member is held along a base of the workpiece by a clamping
force of the caulked portion; and setting a timing for starting a
caulking end process to a timing when a caulking load applied to
the caulking roller during the caulking process or a caulking
torque for rolling the caulking roller undergoes a specific change
indicating that the member begins to be strained.
[0027] By setting as the timing for starting the caulking process
end processing the timing when the caulking load or the caulking
torque undergoes a specific change indicating that the member
begins to be strained as described above, the caulking process can
be ended prior to an increase in the amount of plastic deformation
resulting from application of a pressure to the pressure receiving
shoulder portion even when the pressure is applied to the pressure
receiving shoulder portion during the bending of the end through
the caulking process.
[0028] Thus, the caulked portion side can be prevented from being
strained in the direction of the member in accordance with plastic
deformation of the pressure receiving shoulder portion after the
caulking process. Thus, in the construction in which the member is
held by the caulked portion by applying the pressure to the base of
the caulked retaining member in the same direction as the direction
of the clamping force apart from the caulked portion, the held
member can be restrained from being radially strained through
application of the pressure.
[0029] A fifth aspect of the invention relates to a caulking
apparatus that bends an end of a workpiece along a corner portion
of a member by a caulking surface of a caulking roller, applies a
pressure to a pressure receiving shoulder portion, which is formed
opposite a bent side of the end, in a same direction as a caulking
pressure applied to the caulking surface to thereby carry out a
caulking process and hence form a caulked portion, and carries out
a caulking process of holding the member along a base of the
workpiece by a clamping force of the caulked portion. The caulking
apparatus is equipped with a workpiece mount, a rolling
pressurization unit that presses the workpiece arranged on the
workpiece mount as the caulking roller is rolled over the
workpiece, a caulking process load state detection unit that
detects a caulking process load applied by the caulking roller, a
specific change detection unit that detects a specific change in
the caulking process load detected by the caulking process load
state detection unit that indicates the held member begins to be
strained, and a caulking process changing unit that changes a
caulking process for the workpiece on a basis of a timing at which
the specific change detection unit detects the specific change.
[0030] When the specific change detection unit detects that the
caulking process load state undergoes a specific change indicating
that the member begins to be strained during the caulking process
by the rolling pressurization unit, the caulking process changing
unit changes the caulking process for the workpiece on the basis of
the timing when an occurrence of this specific change is
detected.
[0031] The caulking process is changed by, for example, reducing
the pressure for the caulking process or stopping the caulking
process itself. Thus, the amount of plastic deformation can be
prevented from increasing through application of a pressure to the
pressure receiving shoulder portion.
[0032] Thus, in the caulking apparatus that applies a pressure to
the base of the workpiece in the same direction as the direction of
the clamping force apart from the caulked portion to hold the
member by the caulked portion, the member can be restrained from
being radially strained through application of the pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The foregoing and further features and advantages of the
invention will become apparent from the following description of
example embodiments with reference to the accompanying drawings,
wherein like numerals are used to represent like elements and
wherein:
[0034] FIG. 1 is a longitudinal sectional view of a
rotation-translation conversion actuator according to the first
embodiment of the invention;
[0035] FIG. 2 is a partially cutaway perspective view of a
planetary differential screw type rotation-translation converter
employed in the rotation-translation conversion actuator;
[0036] FIG. 3 is a longitudinal sectional view showing an assembled
rotation-translation conversion actuator according to the first
embodiment of the invention, before caulking;
[0037] FIG. 4 is a sectional view showing the shape of the tip
portion of a bearing holder according to the first embodiment of
the invention before it is caulked;
[0038] FIG. 5 is an explanatory view of the arrangement of a
caulking roller and the bearing holder according to the first
embodiment of the invention;
[0039] FIGS. 6A, 6B, 6C and 6D are explanatory views of the
caulking process according to the first embodiment of the
invention;
[0040] FIGS. 7A, 7B, 7C and 7D are explanatory views of the
caulking process according to the second embodiment of the
invention;
[0041] FIG. 8 is an explanatory view of the configuration of a
caulking apparatus according to the third embodiment of the
invention;
[0042] FIG. 9 is a flowchart of a caulking control process
performed by the caulking apparatus according to the third
embodiment of the invention;
[0043] FIGS. 10A and 10B illustrate graphs showing how the caulking
load and the caulking torque change with respect to a caulking
stroke in the caulking apparatus according to the third embodiment
of the invention;
[0044] FIG. 11 is a flowchart of a caulking control process
executed by a caulking apparatus according to the fourth embodiment
of the invention; and
[0045] FIG. 12 is a graph used in a caulking apparatus according to
the fifth embodiment of the invention and showing the relationship
between a caulking stroke and a bearing strain.
DETAILED DESCRIPTION OF EMBODIMENTS
[0046] A longitudinal sectional view of FIG. 1 represents the
construction of a rotation-translation conversion actuator
(hereinafter referred to as "the actuator") 2 to which the
invention is applied. The actuator 2 may be mounted on an outer
surface of a cylinder head or cam carrier of an internal combustion
engine as a driven object device. In particular, the actuator 2
drives a variable valve operating mechanism mounted on a cylinder
head, and adjusts the axial position of a control shaft installed
in the variable valve operating mechanism. It should be noted
herein that the actuator 2 is mounted on an outer peripheral
surface 4a of a cam carrier 4 as indicated by alternate long and
short dash lines.
[0047] In a housing 6, constituting a body of the actuator 2, a
bearing holder 8 is bolted from the front of the actuator housing 6
(on an F side in FIG. 1) and a stator 10 is bolted from the rear of
the actuator housing 6 (on a B side in FIG. 1). A control panel 12
is bolted to the rear of the housing 6. The housing 6 is thereby
closed.
[0048] Inside the bearing holder 8, a bearing 14 (corresponding to
the member) is retained on a rear side of the bearing holder 8 by a
caulked portion 8b, which is formed through a caulking process as
will be described later. The bearing holder 8 rotatably supports,
via the bearing 14, a nut 16a that constitutes an outer periphery
of a planetary differential screw type rotation-translation
converter 16.
[0049] The planetary differential screw type rotation-translation
converter 16 is provided in the internal space of the housing 6
along the entire axial length of the housing 6. As shown in a
partially cutaway perspective view of FIG. 2, the planetary
differential screw type rotation-translation converter 16 is
includes the nut 16a (corresponding to the rotary member), an
output shaft 16b (corresponding to the sun shaft), and a planetary
shaft 16c arranged between the nut 16a and the output shaft 16b.
The nut 16a meshes with the planetary shaft 16c. By the same token,
the planetary shaft 16c also meshes with the output shaft 16b.
[0050] As shown in FIG. 1, a rotor 18 is press-fitted to the rear
of the nut 16a. The rotor 18 is driven via the stator 10 in
response to a drive signal from the control panel 12, and the nut
16a thereby rotates around its own axis. Due to rotation of this
nut 16a, the planetary shaft 16c revolves around the output shaft
16b while rotating around its own axis. A screw differential effect
is created through rotation of this planetary shaft 16c around its
own axis and revolution around the output shaft 16b. Due to this
screw differential effect, the output shaft 16b, which is
spline-fitted to a tip of the bearing holder 8 to prevent the
output shaft 16b from rotating around its own axis, moves in an
axial direction (in an direction of arrows F-B). In accordance with
the movement of this output shaft 16b in the axial direction, the
control shaft of the variable valve operating mechanism located in
the space within the cam carrier 4 moves in the axial direction,
and the maximum valve lift amount of an intake valve in each
cylinder of the internal combustion engine may be continuously
adjusted through this movement. Thus, the intake air amount of the
internal combustion engine can be continuously adjusted without
using a throttle valve.
[0051] As shown in FIG. 1, the bearing 14 supporting the entire
planetary differential screw type rotation-translation converter 16
includes an outer race 14a that is sandwiched in the axial
direction between an abutment surface 8a formed inside the bearing
holder 8 and the caulked portion 8b at the rear end. Thus, the
entire planetary differential screw type rotation-translation
converter 16 is held at a predetermined position in the housing 6
by the bearing holder 8.
[0052] The caulking process for forming the caulked portion 8b will
now be described. FIG. 3 shows a cross-sectional view of an
assembled rotation-translation conversion actuator before caulking.
Before caulking, an end 8x on the rear end of the bearing holder 8
(corresponding to the caulked retaining member) assumes a
cylindrically rising shape forms a cylindrical projection.
Accordingly, the bearing holder 8 is open on the rear end, and the
planetary differential screw type rotation-translation converter 16
is inserted in the bearing holder 8 from the rear of the bearing
holder 8. Before insertion, the planetary differential screw type
rotation-translation converter 16 is fixed by a snap ring 20 with
the bearing 14 fitted to the outer periphery of the nut 16a. In
addition, a seal ring 22 is also inserted from the rear end of the
bearing holder 8 to be arranged at a predetermined position. It
should be noted that the seal ring 22 is first fitted to the
planetary differential screw type rotation-translation converter 16
in advance and then inserted the insertion of the planetary
differential screw type rotation-translation converter 16.
[0053] In FIG. 4, a partially enlarged view of the rear end of the
bearing holder 8 is shown. In addition to the end 8x, a pressure
receiving shoulder portion 8y, which receives a pressure in the
same direction as the direction of a clamping force exerted by the
caulked portion 8b shown in FIG. 1 (the form of the end 8x
subjected to the caulking process), is formed on the rear end of a
peripheral wall portion 8c of the bearing holder 8 (corresponding
to a base of the bearing holder 8) on an outer periphery side of
the peripheral wall portion 8c outside of the end 8x, which is
formed on the inner periphery side of the peripheral wall portion
8c in this case. A groove 8z with a V-shaped cross-section is
formed between the end 8x and the pressure receiving shoulder
portion 8y.
[0054] In bending the end 8x toward the bearing 14 along a corner
portion of the bearing 14 through the caulking process, the
pressure exerted on the bearing 14 by the caulked portion 8b (the
end 8x) in the same direction as the direction of the clamping
force is also applied to a pressure receiving surface 8d that is a
tip surface of the pressure receiving shoulder portion 8y,
especially in the final stage of the bending of the end 8x. The
pressure receiving surface 8d is set higher than an end surface 14b
of the bearing 14 by a height H.
[0055] The configuration shown in FIG. 3 is arranged in a roll
caulking apparatus to subject the end 8x to a caulking process by
two caulking rollers 24 as shown in FIG. 5. The two caulking
rollers 24 are arranged around an axis B of the bearing holder 8 at
phase intervals of 180.degree., and are rotated around axes of
rotation A respectively. It should be noted in FIG. 5 that the axes
of rotation A of the caulking rollers 24 and the axis B of the
bearing holder 8 are shown parallel to the sheet of the drawing.
The axes of rotation A are perpendicular to the axis B.
[0056] These caulking rollers 24 have stepless cylindrical outer
peripheral surfaces, a portion of which are used as caulking
surfaces 26. The rollers 24 are rotated around their own axes of
rotation A respectively, and at the same time, revolve around the
axis B of the bearing holder 8. The rollers 24 are thus rolled to
press the end 8x on the caulking surfaces 26 formed on the rollers
24 from the state shown in FIG. 6A to that shown in FIG. 6B, and
the end 8x begins bending toward the inner periphery side of the
bearing holder 8 along the end surface 14b of the outer race
14a.
[0057] Immediately before the end of the caulking process, the
regions 27 of the outer peripheral surfaces of the rollers 24 that
are adjacent to the caulking surfaces 26 respectively abut on the
pressure receiving surface 8d of the pressure receiving shoulder
portion 8y as shown in FIG. 6C. Thus, a pressure is applied to the
pressure receiving shoulder portion 8y from the rollers 24. The
pressure is applied in the same direction as the direction of a
clamping force (in the axial direction of the bearing holder 8 in
this case) so that the end 8x is eventually caulked into the
caulked portion 8b to clamp the bearing 14.
[0058] The rollers 24 then press the pressure receiving shoulder
portion 8y to cause plastic deformation while bending the end 8x.
Thus, as shown in FIG. 6D, the end 8x eventually serves as the
caulked portion 8b to clamp the end surface 14b of the bearing 14,
and the caulking process is hence completed.
[0059] In the caulking process as described above, the caulking
surfaces 26 apply pressure to the peripheral wall portion 8c, which
is not to be bent, from the end 8x side in a direction along the
axis B (FIG. 5) (in the direction of the clamping force). However,
the regions 27 adjacent to the caulking surfaces 26 press the
pressure receiving shoulder portion 8y as described above, and the
pressure is thereby applied to the peripheral wall portion 8c in
the same direction from the pressure receiving shoulder portion 8y
as well.
[0060] Accordingly, the peripheral wall portion 8c undergoes
elastic deformation and plastic deformation during deformation of
the end 8x during the caulking process. The ratio of the amount of
plastic deformation increases due to the pressure from the pressure
receiving shoulder portion 8y, and the amount of elastic
deformation decreases correspondingly. It should be noted that the
outer race 14a of the bearing 14, which receives a pressure from
the end surface 14b via the end 8x (which becomes the caulked
portion 8b after the caulking process) during the caulking process,
is made of a hard material and undergoes elastic deformation only.
For example, although both the bearing holder 8 and the outer race
14a are made of steels, the steel of the outer race 14a is harder
than the steel of the bearing holder 8. For example, the bearing
holder 8 may be made of a conventional stainless steel or the like,
and the outer race 14a is made of a hard steel such as high-carbon
chrome steel or the like.
[0061] Due to a difference between the amount of elastic
deformation of the outer race 14a of this bearing 14 and the amount
of elastic deformation of the peripheral wall portion 8c of the
bearing holder 8, a residual axial force is generated in the
bearing holder 8 after the caulking process. Especially due to
pressure of the pressure receiving shoulder portion 8y by the
regions 27 adjacent to the caulking surfaces 26 of the rollers 24,
the amount of plastic flow on the peripheral wall portion 8c side
increases, and the residual axial force thereby increases. Because
the residual axial force thus increased, the outer race 14a
receives a clamping pressure from the caulked portion 8b while
abutting on the abutment surface 8a, and the entire bearing 14 is
reliably held in the bearing holder 8. Thus, the nut 16a of the
planetary differential screw type rotation-translation converter 16
is rotatably supported in the bearing holder 8.
[0062] In the caulking process, plastic deformation resulting from
press of the pressure receiving shoulder portion 8y causes the
peripheral wall portion 8c to bulge toward the inner periphery side
as well as toward the outer periphery side. In this embodiment of
the invention, the peripheral wall portion 8c is prevented from
bulging toward this inner periphery side according to two
methods.
[0063] In the first method, as shown in FIG. 4, the pressure
receiving surface 8d of the pressure receiving shoulder portion 8y
is set higher than the end surface 14b of the outer race 14a of the
bearing 14. Thus, the bulge formed in the peripheral wall portion
8c, toward the inner periphery side, due to plastic deformation
caused by transmission of a pressure toward the inner periphery is
absorbed by a range I shown in FIG. 4 so that the pressure does not
deform the outer race 14a of the bearing 14 inward. The range I is
obtained by adding a range where the outer race 14a of the bearing
14 is spaced apart from an inner surface of the bearing holder 8 to
a range higher than the end surface 14b of the outer race 14a. In
this embodiment of the invention, the range I is higher than a
rounded region R of the corner portion of the outer race 14a.
[0064] In the second method, the groove 8z exists between the end
8x and the pressure receiving shoulder portion 8y. Thus, even if
the pressure is transmitted to the inner periphery side, most of
the plastic deformation resulting from the transmission of the
pressure is absorbed by the groove 8z.
[0065] Thus, pressure of the pressure receiving shoulder portion 8y
does not cause the bearing 14 located in the bearing holder 8 to be
strained radially inward after the caulking process, and does not
affect the rotational resistance of the nut 16a of the planetary
differential screw type rotation-translation converter 16.
[0066] According to the first embodiment of the invention in which
a method for retaining a member by caulking and a structure of
caulked retaining member are realized with the aid of the caulked
retaining member as described above, the following effects are
obtained. 1) In subjecting the end 8x of the bearing holder 8 to
the caulking process, the pressure is applied to the pressure
receiving shoulder portion 8y in the same direction as the
direction of the clamping force generated by the caulked portion
8b. Thus, as described above, the residual axial force in the
bearing holder 8 is larger after the completion of the described
caulking process than in the case of a conventional caulking
process. Thus, the clamping force for holding the outer race 14a
may be increased.
[0067] In addition, the pressure receiving surface 8d of the
pressure receiving shoulder portion 8y is set higher than the end
surface 14b of the outer race 14a. Thus, no pressure results from
plastic deformation of the caulked portion 8b in the direction
perpendicular to the direction of the clamping force. In addition,
the groove 8z is formed between the pressure receiving shoulder
portion 8y and the end 8x serving as the caulked portion 8b. Due to
these, even when plastic deformation occurs through application of
the pressure to the pressure receiving shoulder portion 8y
simultaneously with the bending of the end 8x through the caulking
process as described above, plastic flow does not affect the
bearing 14 side. Thus, the bearing 14 is restrained from being
radially strained, namely, from being so strained as to increase
the rotational resistance thereof in accordance with deformation of
the pressure receiving shoulder portion 8y during the caulking
process.
[0068] 2) The invention is applied to the caulking process in which
the bearing 14 for rotatably supporting the planetary differential
screw type rotation-translation converter 16 is arranged in the
bearing holder 8. Therefore, a large residual axial force may be
set for the bearing holder 8, and the bearing 14 may be reliably
held while being prevented from being radially strained. As a
result, the size of the actuator may be reduced, and energy for
driving the actuator can be conserved. In particular, because the
driven object device is an internal combustion engine, size
reduction and energy conservation are made possible for the
internal combustion engine, and fuel economy is improved.
[0069] 3) The same rollers 24 are used to subject the end 8x of the
bearing holder 8 to the caulking process and apply the pressure to
the pressure receiving shoulder portion 8y of the bearing holder 8.
In addition, the rollers 24 are formed as stepless cylindrical
surfaces. Thus, the caulking process may be efficiently carried out
using a simple configuration. Furthermore, the shape of the rollers
24 is simplified, so it becomes easy to reduce the cost of the
caulking apparatus and increase the accuracy in caulking the
bearing holder 8.
[0070] In the second embodiment of the invention, as shown in FIG.
7A, a bearing holder 108 has an end 108x serving as a caulked
portion 108b after a caulking process, and a pressure receiving
shoulder portion 108y having a pressure receiving surface 108d
formed on an outer periphery side with respect to the end 108x.
However, a groove or the like is not provided between the end 108x
and the pressure receiving shoulder portion 108y. The second
embodiment of the invention is identical to the first embodiment of
the invention in other structural details.
[0071] Using this bearing holder 108, as shown in FIGS. 7B to 7D,
the caulking process is carried out with the aid of rollers 124
forming stepless cylindrical outer peripheral surfaces as in the
case of the first embodiment of the invention. In the final stage
of the caulking process, a pressure is applied to the pressure
receiving surface 108d of the pressure receiving shoulder portion
108y as shown in FIGS. 7C and 7D.
[0072] In this embodiment of the invention, because no gap is
provided between the end 108x and the pressure receiving shoulder
portion 108y, the effect of absorbing radially inward plastic flow
decreases correspondingly. However, because the pressure receiving
surface 108d of the pressure receiving shoulder portion 108y is set
higher than an end surface 114b of a bearing 114, plastic flow is
absorbed correspondingly. As a result, an effect of preventing the
bearing 114 from being radially strained is exerted.
[0073] The other effects are the same as described in the first
embodiment of the invention. In the third embodiment of the
invention, a caulking process is carried out using a caulking
apparatus 223 shown in FIG. 8. Two caulking rollers 224 are
arranged to face each other at phase intervals of 180.degree.
around an axis Ax of a bearing holder 208 arranged on a work mount.
The axis of rotation Bx common to the two caulking rollers 224 is
perpendicular to the axis Ax of the bearing holder 208.
[0074] These caulking rollers 224 are lowered along the axis Ax of
the bearing holder 208 to bring cylindrical caulking surfaces 228
formed on outer peripheries of the caulking rollers 224 into
contact with an end 208x of the bearing holder 208. The caulking
rollers 224 are then rotated around the axis Ax of the bearing
holder 208 by a rotation mechanism 223a provided in the caulking
apparatus 223. Through the rotation of the caulking rollers, a
pressure is applied to rotational shaft bodies 224a of the caulking
rollers 224 from a pressurization mechanism 223b installed in the
caulking apparatus 223, downward along the axis Ax of the bearing
holder 208.
[0075] The pressurization mechanism 223b is provided with a
pressure generation device for generating a hydraulic pressure or
the like and a pressure adjustment mechanism. The pressure
adjustment mechanism applies a caulking load Fp required for the
caulking process to the caulking rollers 224. This caulking load Fp
(N) may be detected by a process measurement portion 223c to be
used for an automatic processing by a caulking process control
portion 223d. Furthermore, in the process measurement portion 223c,
a caulking stroke Lp (mm), namely, a moving amount of the process
rollers 224 in the direction of the axis Ax of the bearing holder
208 is also detected to be output to the caulking process control
portion 223d.
[0076] The caulking rollers 224 are supported around the axis Bx
rotatably around their own axes via the rotational shaft bodies
224a respectively and hence are rotated around their own axes while
revolving around the axis Bx through caulking process. That is, the
caulking rollers 224 are rolled.
[0077] The shapes of the end 208x of the bearing holder 208 and the
pressure receiving shoulder portion 208y of the bearing holder 208
are the same as shown in the first embodiment or the second
embodiment of the invention. Accordingly, the caulking rollers 224
are brought into contact with the end 208x of the bearing holder
208 as described above, then brought into contact with the pressure
receiving surface 208d of the pressure receiving shoulder portion
208y in the final stage of the caulking process, and rolled, and
the caulking process as described in the first embodiment or the
second embodiment of the invention is thereby be carried out.
[0078] It should be noted herein that the caulking process control
portion 223d is mainly constituted by a microcomputer. A flowchart
of FIG. 9 shows a caulking control process executed by the caulking
process control portion 223d. The proces is executed at
predetermined intervals. It should be noted that the steps in the
flowchart corresponding to individual processing contents are
denoted by "S.about." respectively.
[0079] When the present processing is started, it is first
determined whether the caulking process is being carried out
(S102). If the caulking process is not being carried out (NO in
S102), the present processing is immediately terminated. If the
caulking apparatus 223 is operated to start the caulking process,
the caulking process is being carried out (YES in S102).
Accordingly, the caulking load Fp and the caulking stroke Lp, which
are detected by the process measurement portion 223c, are then read
into a working area provided in a transient memory of the caulking
process control portion 223d (S104).
[0080] A caulking load change amount dFp for a last constant stroke
change amount dLp (e.g., a stroke change amount of 0.1 mm) is then
calculated (S106). That is, the difference between the caulking
load Fp after the caulking rollers 224 are lowered by a
predetermined stroke and the caulking load Fp before the caulking
rollers 224 are lowered is calculated as the caulking load change
amount dFp. The caulking load change amount dFp is calculated using
formula 1 (S108).
dFp<Adfp+dx (Formula 1)
[0081] The right side of the formula 1 represents a value larger
than a later-described caulking load change amount moving average
Adfp by a divergence amount dx. That is, the formula 1 is used to
determine whether the caulking load change amount dFp is smaller
than the sum of the caulking load change amount moving average Adfp
and the divergence amount dx.
[0082] More specifically, the caulking load Fp changes as shown in
FIG. 10A as the caulking stroke Lp changes. In FIG. 10A, the
caulking process is started slightly before the caulking stroke Lp
becomes equal to 1 mm. After that, the caulking load Fp rises at a
substantially constant gradient shortly after the caulking stroke
Lp exceeds 4 mm. The constant change in the caulking load Fp at a
substantially constant gradient arises in the course of bending the
end 208x (8x, 108x) as shown in FIGS. 6B and 6C and FIGS. 7B and
7C.
[0083] Then, when the rollers 224 (24, 124) press the pressure
receiving shoulder portion 208y (8y, 108y) as well to bring the end
208x (8x, 108x) into contact with the end surface 214b (14b, 114b)
of the bearing 214 (14, 114) as shown in FIGS. 6C and 6D and FIGS.
7C and 7D, the caulking load Fp begins to increase abruptly as
indicated by a stroke point Lx in FIG. 10A. Accordingly, when the
caulking stroke Lp reaches this stroke point Lx, the caulking
process is completed.
[0084] That is, the formula 1 serves to determine whether the
stroke point Lx, where the caulking load Fp begins to increase
abruptly, has been reached. In this case, if the relationship
dFp<Adfp+dx is satisfied (YES in S108), the caulking stroke Lp
has not reached the stroke point Lx. Accordingly, the caulking load
change amount moving average Adfp is calculated using formula 2
(S110).
Adfp.rarw.(nAdfp+dFp)/(n+1) (Formula 2)
[0085] It should be noted herein that the caulking load change
amount moving average Adfp on the right side of Formula 2 is a
value calculated during the previous control cycle (a value used in
the last step S108), and that the caulking load change amount
moving average Adfp on the left side is a currently updated value.
The value n representing number of times is set to, for example,
10. It should be noted that the calculation according to formula 2
may be made immediately before step S108.
[0086] The present process is thus terminated. After that, when the
caulking process is being carried out and formula 1 continues to be
satisfied in the subsequent caulking control process (YES in S108),
the caulking load change amount moving average Adfp continues to be
calculated according to formula 2 (S110).
[0087] Then, when the caulking stroke reaches the stroke point Lx,
where the relationship dFp.gtoreq.Adfp+dx is satisfied (NO in
S108), a caulking stop process is executed (S112). In the caulking
stop process, more specifically, the application of the pressure to
the bearing holder 208 is stopped by raising the caulking rollers
224, and the caulking rollers 224. Furthermore, the rolling of the
caulking rollers 224 by the rotation mechanism 223a is stopped.
[0088] Due to the execution of the caulking stop process as
described above, the caulking process is not being carried out (NO
in S102) in the subsequent caulking control process. Therefore, the
present processing is terminated. Further, when the caulking
process is next carried out, the result of the determination in
step S102 is YES. Then in the process as described above, press and
rolling are continued by the caulking rollers 224 until the
caulking process is completed.
[0089] In the above configuration, the rotation mechanism 223a and
the pressurization mechanism 223b are equivalent to the rolling
pressurization unit, and the process measurement portion 223c is
equivalent to the caulking process load state detection unit. The
caulking process control portion 223d is equivalent to the specific
change detection unit and the process changing unit. Steps S104,
S106, S108, and S110 of the caulking control process (FIG. 9) are
equivalent to the processes executed by the specific change
detection unit, and step S112 is equivalent to the process executed
by the process changing unit.
[0090] According to the third embodiment of the invention, the
following effects are obtained. 1) In accordance with the
construction of the bearing holder used for the caulking process,
the effects of the first embodiment or the second embodiment of the
invention are obtained.
[0091] 2) When the end 208x of the bearing holder 208 is subjected
to the caulking process, the caulking apparatus 223 changes the
caulking process for the bearing holder 208 at a timing at which a
specific change occurs that indicates the bearing 214 begins to be
strained. More specifically, the caulking process is
terminated.
[0092] Thus, by reducing the pressure for the caulking process or
stopping the caulking process, increases in the amount of plastic
deformation resulting from application of the pressure to the
pressure receiving shoulder portion 208y may be prevented.
[0093] Accordingly, the caulking apparatus 223 may reliably
restrain the bearing 214 from being radially strained as a result
of application of the pressure in carrying out the caulking
process. In the fourth embodiment of the invention, the caulking
control process shown in FIG. 11 is performed at predetermined
intervals. Furthermore, a process measurement portion that detects
the caulking stroke Lp (mm) and the caulking torque Tp (Nm) is
employed as the process measurement portion 223c. The caulking
torque Tp is applied to the bearing holder 208 when the caulking
rollers 224 rotate around the axis Ax of the bearing holder 208 by
means of the rotation mechanism 223a. It should be noted that the
energy for rotating the rotation mechanism 223a at a constant
speed, namely, the electric power supplied to an electric motor,
may be used as a value indicative of the caulking torque Tp instead
of detecting the caulking torque Tp using the process measurement
portion 223c. The fourth embodiment of the invention is identical
to the third embodiment of the invention in other structural
details. Therefore, the caulking control process (FIG. 11) will be
described with reference to FIGS. 8 and 10.
[0094] When the present process is started, it is first determined
whether the caulking process is being carried out (S202). If the
caulking process is not being carried out (NO in S202), the present
processing is immediately terminated. If the caulking apparatus 223
is operated to start the caulking process (YES in S202), the
caulking torque Tp and the caulking stroke Lp, which are detected
by the process measurement portion 223c, are then stored into the
working area of the memory (S204).
[0095] A caulking torque change amount dTp for the previous
constant stroke change amount dLp (e.g., the stroke change amount
of 0.1 mm) is then calculated (S206). The caulking torque change
amount dTp is calculated using formula 3 (S208).
dTp>Bdtpdy (Formula 3)
[0096] The right side of formula 3 represents a value smaller than
a later-described caulking torque change amount moving average Bdtp
by a divergence amount dy. That is, formula 3 is used to determine
whether the caulking torque change amount dTp exceeds a value
obtained by subtracting the divergence amount dy from the caulking
torque change amount moving average Bdtp.
[0097] More specifically, the caulking torque Tp changes as shown
in FIG. 10B as the caulking stroke Lp changes. In FIG. 10B, the
caulking torque Tp changes without drastically decreasing from the
start of the caulking process shortly after the caulking stroke Lp
exceeds 4 mm. This arises in the course of bending the end 208x
(8x, 108x) as shown in FIGS. 6B and 6C and FIGS. 7B and 7C.
[0098] Then, when the end 208x (8x, 108x) comes into contact with
the end surface 214b (14b, 114b) of the bearing 214 (14, 114) as
shown in FIGS. 6C and 6D and FIGS. 7C and 7D, the caulking torque
Tp starts abruptly decreasing as indicated by a stroke point Ly in
FIG. 10B. This indicates that the bending of the end 208x of the
bearing holder 208 and plastic deformation of the pressure
receiving shoulder portion 208y are terminated to cause a decrease
in the resistance against the rolling of the caulking rollers 224.
Accordingly, when the caulking stroke Lp reaches this stroke point
Ly, the caulking process is completed.
[0099] That is, formula 3 is used to determine whether the caulking
stroke Lp has reached the stroke point Ly, where the caulking
torque Tp begins to decrease abruptly. The stroke position is
substantially the same as the stroke point Lx, as shown in FIG.
10A.
[0100] In this case, if the relationship dTp>Bdtp-dy is
satisfied (YES in S208), the caulking stroke Lp has not reached the
stroke point Ly. Accordingly, the caulking torque change amount
moving average Bdtp is then calculated using formula 4 (S210).
BdTp.rarw.(mBdtp+dTp)/(m+1) (Formula 4)
[0101] It should be noted herein that the caulking torque change
amount moving average Bdtp on the right side is a value calculated
during the previous control cycle (a value used in a step S208
executed previously), and that the caulking torque change amount
moving average Bdtp on the left side is the current value. A value
m representing number of times is set to, for example, 10. It
should be noted that the calculation according to formula 4 may be
made immediately before step S208.
[0102] After that, when the caulking process is being carried out
and formula 3 continues to be satisfied (YES in S208), the caulking
torque change amount moving average
[0103] Bdtp continues to be calculated according to formula 4
(S210).
[0104] Then, when the caulking stroke Lp reaches the stroke point
Ly where the relationship dTp.ltoreq.Bdtp-dy is satisfied (NO in
S208), the caulking stop process is executed (S212). The caulking
stop process is the same as that described in step S112 of the
third embodiment of the invention.
[0105] In the above configuration, steps S204, S206, S208, and S210
of the caulking control process (FIG. 11) are equivalent to the
processes executed by the specific change detection unit, and step
S212 is equivalent to the process executed by the process changing
unit.
[0106] As described above, in this embodiment of the invention, the
determination of whether to stop the caulking process is based on
the caulking torque change amount dTp. The effects described in the
third embodiment of the invention are obtained from this as
well.
[0107] In the fifth embodiment of the invention, the caulking stop
process (S112, S212) executed in the caulking control process
(FIGS. 9 and 11) differs in that the caulking process continues for
a brief period before the caulking stop process is executed as
described above.
[0108] That is, as shown in FIG. 12, when the caulking process
progresses beyond the stroke point Lx, Ly (the origin in FIG. 12),
the strain of the bearing 214 is caused and increased as the
caulking stroke Lp increases. If the strain of the bearing 214 is
within a permissible range, it is preferable, in view of various
errors during the process, to stop the caulking process after the
caulking stroke Lp slightly exceeds the stroke point Lx, Ly, so
that the bearing 214 is held with a sufficient clamping force.
[0109] For example, if the permissible range of the strain of the
bearing 214 is equal to or smaller than 5 .mu.m, it was
experimentally determined that the caulking stroke Lp may exceed
the stroke point Lx or Ly by 0.2 mm. Accordingly, a shift to the
caulking stop process (S112, S212) is made after the caulking
stroke Lp exceeds the stroke point Lx, Ly by a value smaller than
0.2 mm, for example, 0.1 mm.
[0110] Thus, the effects of the third embodiment of the invention
or fourth embodiment of the invention are achieved, and the
caulking process may be reliably carried out in view of various
errors during the caulking process. Modified examples will be
described hereinafter. (a) In each described embodiment of the
invention, the caulking apparatus includes two caulking rollers
arranged around the axis of the bearing holder at phase intervals
of 180.degree.. However, the caulking apparatus may have only one
caulking roller. Alternatively, a caulking apparatus having three
caulking rollers arranged at phase intervals of 120.degree. or a
caulking apparatus having four caulking rollers arranged at phase
intervals of 90.degree. may be employed.
[0111] (b) In each of the described embodiments, the outer race of
the bearing is clamped by the bearing holder. However, it is also
appropriate to adopt a structure in which the caulked portion is
formed directly on the housing through a caulking process and the
outer race of the bearing is directly held by the housing instead
of using the bearing holder. In this case as well, an effect
similar to that of the case where the pressure receiving shoulder
portion is formed on the housing and held by the bearing holder as
described above through application of the pressure is
obtained.
[0112] In each embodiment of the invention, the pressure receiving
shoulder portion is described as being formed on the bearing holder
or the housing for the purpose of application of the pressure.
However, if the bearing holder or the housing already has a region
to which a pressure may be applied in the direction of the clamping
force of the outer race, that region may be utilized as the
pressure receiving shoulder portion instead.
[0113] Further, the pressure receiving shoulder portion is pressed
by the same rollers as the caulking rollers for subjecting the end
to the caulking process. However, the pressure receiving shoulder
portion may be pressed by a different type of pressurization
mechanism. Even if the same caulking rollers as described above are
used, the rollers may have a caulking surface and a pressurization
surface that are different in level from each other instead of
having a stepless cylindrical surface.
[0114] (d) In each of the above-described caulking control
processes, the caulking load change amount moving average Adfp
(FIG. 9: S110) or the caulking torque change amount moving average
Bdtp (FIG. 11: S210) is calculated, and the caulking process stop
process is started when the difference between the latest caulking
load Fp or the latest caulking torque Tp and the moving average
value exceeds the divergence amount dx or dy. Instead of
calculating the moving average value and making a determination as
described above, it is also appropriate to provide a filter circuit
to filter a signal output from the process measurement portion 223c
and make a determination on a sudden change in the caulking load Fp
or the caulking torque Tp in accordance with the filtered
signal.
[0115] (e) In each of the foregoing embodiments of the invention,
the variable valve operating mechanism that adjusts the maximum
valve lift amount of each intake valve provided in the internal
combustion engine is employed as the mechanism driven by the
rotation-translation conversion actuator. However, a variable valve
operating mechanism capable of continuously adjusting the maximum
valve lift amount of each exhaust valve provided in the internal
combustion engine may be employed instead. Furthermore, a mechanism
other than the variable valve operating mechanism may be employed
as the mechanism driven by the rotation-translation conversion
actuator. Further, this mechanism may not necessarily be used for
the internal combustion engines.
[0116] (f) In each of the described embodiments of the invention,
the planetary differential screw type rotation-translation
converter is adopted as the rotation-translation converter.
However, a different type of rotation-translation converter such as
a feed screw mechanism may be employed.
[0117] (g) As described in FIG. 4 of the first embodiment of the
invention, the strain toward the outer race 14a side of the bearing
14, which is caused through pressurization of the pressure
receiving surface 8d, is absorbed by the range I including the
rounded region R of the corner portion of the outer race 14a.
Accordingly, the creation of a strain leading to an increase in the
rotation resistance of the bearing 14 can also be suppressed by
setting the height of the pressure receiving surface 8d higher than
a lowest position of this rounded region R.
* * * * *