Information
-
Patent Grant
-
6827052
-
Patent Number
6,827,052
-
Date Filed
Friday, March 28, 200321 years ago
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Date Issued
Tuesday, December 7, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
- Denion; Thomas
- Riddle; Kyle M.
Agents
- Burns, Doane, Swecker & Mathis, L.L.P.
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CPC
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US Classifications
Field of Search
US
- 123 9027
- 123 9031
- 464 1
- 464 2
- 464 160
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International Classifications
-
Abstract
A variable valve timing control device includes a rotation member unitary fixed to a rotation shaft for controlling a valve timing assembled to a cylinder head of an internal combustion engine to be rotatable, a rotation transmission member engaged with the rotation member to be relatively rotatable, a vane provided on either one of the rotation member or the rotation transmission member, a hydraulic pressure chamber formed between the rotation member and the rotation transmission member and is divided into an advance angle chamber and a retarded angle chamber by the vane, and a detection member for detecting a relative rotation phase between the rotation member and a crankshaft. The detection member is press fitted into a cylindrical portion formed in an axial direction of the rotation member and the rotation member is fixed to the rotation member by a tightening member.
Description
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Patent Application No. 2002-090250 filed on Mar. 28, 2002, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a variable valve timing control device. More particularly, the present invention pertains to a variable valve timing control device for controlling a valve timing of intake and exhaust valves for an internal combustion engine.
BACKGROUND OF THE INVENTION
A known variable valve timing control device is disclosed in Japanese Patent Laid-Open Publication No. 2001-355468. The variable valve timing control device disclosed in Japanese Patent Laid-Open Publication No. 2001-355468 includes a rotation member unitary fixed to a rotation shaft for opening and closing valve rotatably assembled to a cylinder head of the internal combustion engine, a rotation transmission member engaged to the rotation member to be relatively rotatable, vanes provide on either one of the rotation member or the rotation transmission member, hydraulic pressure chambers formed between the rotation member and the rotation transmission member and divided into an advance angle chamber and a retarded angle chamber by the vane, and a detection member for detecting a relative rotation phase between the rotation member and a crankshaft.
With the foregoing known variable valve timing control device, the detection member is fitted into a cylindrical concave portion formed on the rotation member and is sandwiched between a rotation shaft and a tightening member by a screw connection of the tightening member and the rotation shaft. The detection member is formed by any one of unitary stamping and cutting, sintering unitary molding and cutting, or coupling of two parts.
Notwithstanding, with the known detection member, it is required to increase the precision of a fitting portion and a tightening seat surface, and thus the manufacturing cost is increased by for example, cutting. In addition, because the tightening force of the tightening member is received by the tightening seat surface, it is required to apply the material with high critical surface pressure or it is required to apply the heat treatment, the manufacturing cost is increased. In order to avoid the rotation of the detection member along with the rotation of the tightening member when tightening, the assembling becomes complex for preventing the rotation of the rotation member by an assembling jig or a rotation prevention mechanism.
A need thus exists for a variable valve timing control device which fixes a detection member for detecting a relative rotation phase between a rotation member and a crankshaft with low cost and simple construction.
SUMMARY OF THE INVENTION
In light of the foregoing, the present invention a variable valve timing control device which includes a rotation member unitarily fixed to a rotation shaft for opening and closing a valve assembled to a cylinder head of an internal combustion engine to be rotatable, a rotation transmission member engaged with the rotation member to be relatively rotatable, a vane provided on the rotation member or the rotation transmission member, a hydraulic pressure chamber formed between the rotation member and the rotation transmission member and divided into an advance angle chamber and a retarded angle chamber by the vane, and a detection member for detecting a relative rotation phase between the rotation member and a crankshaft. The detection member is press fitted into a cylindrical portion formed in an axial direction of the rotation member and the rotation member is fixed to the rotation member by a tightening member.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawing figures in which like reference numerals designate like elements.
FIG. 1
is a cross-sectional view of a variable valve timing control device according to an embodiment of the present invention.
FIG. 2
is a cross-sectional view taken on line II—II of
FIG. 1
of the variable valve timing control device according to the embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of a variable valve timing control device will be explained with reference to the illustrations of the drawing figures.
As shown in
FIGS. 1-2
, the variable valve timing control device includes a rotor
20
(i.e., serving as a rotation member) unitary assembled to a tip end portion of a camshaft
10
(i.e., serving as a rotation shaft) rotatably supported by a cylinder head
110
of an internal combustion engine, a housing
30
(i.e., serving as a rotation transmission member) is assembled to an external periphery of the rotor
20
to be relatively rotatable within a predetermined angle. A timing sprocket
31
is unitary formed on an external periphery of the housing
30
, and four vanes
70
assembled to the rotor
20
. The timing sprocket
31
is transmitted with rotational force from a crankshaft
130
via a crank sprocket (not shown) and a timing chain
120
. Although the rotation of the crankshaft
130
of the internal combustion engine is transmitted to the timing sprocket
31
of the housing
30
via the timing chain
120
with this embodiment, the construction is not limited to this embodiment. For example, a belt member may be applied in place of the timing chain and the timing sprocket
31
may be replaced by a pulley.
The rotor
20
having a stepped cylindrical configuration at a center thereof is formed with a cylindrical portion
20
a
and a penetration bore
20
b
in an axial direction. The rotor
20
includes a recess portion
20
d
on an end surface to which the camshaft
10
is positioned to be assembled. A single assembling bolt
90
penetrated through the penetration bore
20
b
contacts a seat surface
20
c
formed on an end portion of the cylindrical portion
20
a
to be tightened to the camshaft
10
for fixing the rotor
20
. Approximately disc shaped sensor wheel
45
is press fitted to be fixed on an external periphery
20
e
of the cylindrical portion
20
a
. When the rotor
20
is fixed to the camshaft
10
via the assembling bolt
90
, the external periphery
20
e
of the cylindrical portion
20
a
is slightly deformed in radial direction by the axial tension of the assembling bolt
90
, the tension between the cylindrical portion
20
a
and the sensor wheel
45
is increased, and the deviation of the sensor wheel
45
relative to the rotor
20
by the impact torque received from the camshaft
10
is eradicated. Although the bolt seat surface
20
c
has the same height with the sensor wheel
45
according to
FIG. 1
, the height of the bolt seat surface
20
c
is not limited to this height. Four advance angle passages
23
and four retarded angle passages
24
extend in the radial direction, four vane grooves
21
and a receiving groove
22
are provided outwardly on the rotor
20
. Four vanes
70
are provided in respective vane grooves
21
to be radially movable. A leaf spring
25
is provided between a bottom of the vane groove
21
and a bottom surface of the vane
70
. Thus, the vanes
70
are outwardly biased to slide on a sliding surface of the housing
30
. The receiving groove
22
is provided with a lock key
80
which head portion is inserted in the receiving groove
22
by a predetermined amount when a relative position of the camshaft
10
and the rotor
20
and the housing
30
is synchronized at a predetermined phase (i.e., most retarded angle position) as shown in FIG.
2
. The receiving groove
22
is in communication with the advance angle passages
23
.
The housing
30
is assembled to an external periphery of the rotor
20
to be relatively rotatable within a predetermined angle. The timing sprocket
31
is unitary formed on the external periphery of the housing
30
.
Four convex portions
33
are formed on an internal periphery of the housing
30
in the peripheral direction. The internal peripheral surface of the convex portions
33
contacts an external peripheral surface of the rotor
20
so that the housing
30
is rotatably supported by the rotor
20
. One of the convex portions
33
is formed with a retraction groove
34
for accommodating the lock key
80
and an accommodation groove
35
for a spring
60
biasing the lock key
80
in the radially inward direction.
The vane
70
divides a hydraulic pressure chamber R
0
formed between adjacent convex portions
33
in peripheral direction and between the housing
30
and the rotor
20
into an advance angle chamber R
1
and a retarded angle chamber R
2
. The relative rotation of a vane
70
a
is restricted at a position contacting one side surface
33
a
of the convex portion
33
in the periphery direction on the most advance angle side. The relative rotation of the vane
70
a
is restricted at a position contacting the other side surface
33
b
of the convex portion
33
in the periphery direction on the most retarded angle side. The relative rotation between the rotor
20
and the housing
30
is restricted by inserting the head portion of the lock key
80
into the receiving groove
22
on the retarded angle side.
The operation of the variable valve timing control device of the embodiment with the foregoing construction will be explained as follows.
The variable valve timing control device obtains a desired valve timing by controlling the relative rotation of the rotor
20
relative to the housing
30
by adjusting the hydraulic pressure in the advance angle chamber R
1
and the retarded angle chamber R
2
. In this case, it is judged whether the desired valve timing is obtained by comparing a rotation phase detected by a sensor (not shown) from the sensor wheel
45
unitary rotated with the rotor
20
and a rotation phase detected by a sensor (not shown) provided on a crankshaft portion.
When the internal combustion engine is stopped, the head portion of the lock key
80
is inserted into the receiving groove
22
of the rotor
20
by a predetermined amount to lock the relative rotation between the rotor
20
and the housing
30
at the most retarded angle position.
When the advance angle is required for a valve timing in accordance with the operation conditions after starting the internal combustion engine, the operation fluid supplied from an oil pump (not shown) by the operation of a switching valve (not shown) is applied to the advance angle chamber RI via the advance angle passages
23
. The operation fluid is supplied to the receiving groove
22
from the advance angle passage
23
. On the other hand, the operation fluid in the retarded angle chamber R
2
is discharged to an oil pan (not shown) from the switching valve via the retarded angle side passages
24
. In this case, the lock key
80
moves against the biasing force of the spring
60
and the head portion of the lock key
80
is removed from the receiving groove
22
to release the lock between the rotor
20
and the housing
30
. Accordingly, the rotor
20
and the vanes
70
unitary rotated with the camshaft
10
rotates towards the advance angle side R relative to the housing
30
.
When the retarded angle is required for the valve timing in accordance with the operation conditions, the operation fluid supplied from the oil pump is supplied to the retarded angle chamber R
2
via the retarded angle passage
24
by the operation of the switching valve. On the other hand, the operation fluid in the advance angle chamber R
1
is discharged to the oil pan from the switching valve via the advance angle passage
23
. Thus, the rotor
20
and the vanes
70
are rotated towards the retarded angle side relative to the housing
30
.
According to the embodiment of the present invention, because the tightening force from the seat surface of the assembling bolt is received by the rotor, high critical surface pressure of the sensor wheel
45
is not required. Thus, the inexpensive material can be applied. In addition, because such materials have favorable formability, the unitary stamping can be performed and cutting is not required. Further, because the rotation by the tightening force from the seat surface of the assembling bolt is received by the rotor, the rotation of the sensor wheel
45
following the rotation of the tightening member can be eradicated and the assembling jig and the rotation prevention mechanism for preventing following rotation are not required.
According to the embodiment of the present invention, the axial tension of the assembling bolt is applied to the rotor in the axial direction to slightly expand the rotor in the radial direction and thus the tension between the external periphery of the cylindrical portion and the sensor wheel can be improved. In case simply the dimension of press fitting portion is increased by adjusting the dimension of the rotor and the sensor wheel, the drawback that the sensor is not enabled to be press fitted perpendicularly due to the scratching is caused. With the embodiment of the present invention, the tension can be increased by further increasing the dimension of press fitting portion by the slight expansion of the rotor by the axial force of the assembling bolt after press fitting with the dimension of press fitting portion which achieves appropriate press fitting. Thus, the deviation of the sensor wheel relative to the rotor by the impact torque received from the camshaft can be eradicated at the engine operation.
The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiment disclosed. Further, the embodiment described herein is to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
Claims
- 1. A variable valve timing control device comprising:a rotation member unitarily fixed to a rotation shaft for controlling a valve timing assembled to a cylinder head of an internal combustion engine to be rotatable; a rotation transmission member engaged with the rotation member to be relatively rotatable; a vane provided on either the rotation member or the rotation transmission member; a hydraulic pressure chamber formed between the rotation member and the rotation transmission member, the hydraulic pressure chamber being divided into an advance angle chamber and a retarded angle chamber by the vane; a detection member for detecting a relative rotation phase between the rotation member and a crankshaft; the detection member being press fitted to an external periphery of a cylindrical portion formed in an axial direction of the rotation member, and the rotation member being fixed to the rotation shaft by a tightening member; and wherein the external periphery of the cylindrical portion is deformed in a radial direction by axial force of the tightening member.
- 2. A variable valve timing control device comprising:a rotation member unitarily fixed to a rotation shaft by a tightening member for controlling a valve timing assembled to a cylinder head of an internal combustion engine to be rotatable; a rotation transmission member engaged with the rotation member to be relatively rotatable; a vane provided on either the rotation member or the rotation transmission member; a hydraulic pressure chamber formed between the rotation member and the rotation transmission member, the hydraulic pressure chamber being divided into an advance angle chamber and a retarded angle chamber by the vane; a detection member for detecting a relative rotation phase between the rotation member and a crankshaft; the detection member being press fitted to an axially extending cylindrical portion of the rotation member at a position between where an end portion of the cylindrical portion contacts the rotation shaft and where an oppositely located end portion of the cylindrical portion contacts the tightening member.
- 3. A variable valve timing control device comprising:a rotation member unitarily fixed by a bolt to a rotation shaft assembled to a cylinder head of an internal combustion engine to be rotatable; the bolt contacting an axially facing surface at an end portion of the rotation member; a rotation transmission member engaged with the rotation member to be relatively rotatable; a vane provided on either the rotation member or the rotation transmission member; a hydraulic pressure chamber formed between the rotation member and the rotation transmission member, the hydraulic pressure chamber being divided into an advance angle chamber and a retarded angle chamber by the vane; a sensor wheel adapted to detect a relative rotation phase between the rotation member and a crankshaft; the sensor wheel being mounted on the end portion of the rotation member at a position where axial tension of the bolt resulting from tightening the bolt to the rotation shaft produces radial expansion of the rotation member which acts on the sensor wheel.
- 4. The variable valve timing control device according to claim 3, wherein the sensor wheel is press fitted onto an outer periphery of the rotation member before the bolt is tightened to produce the radial expansion of the rotation member.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2002-090250 |
Mar 2002 |
JP |
|
US Referenced Citations (3)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2001-355468 |
Dec 2001 |
JP |