U.S. patent application number 11/896536 was filed with the patent office on 2008-04-10 for valve timing controller.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Yasushi Morii.
Application Number | 20080083384 11/896536 |
Document ID | / |
Family ID | 39154759 |
Filed Date | 2008-04-10 |
United States Patent
Application |
20080083384 |
Kind Code |
A1 |
Morii; Yasushi |
April 10, 2008 |
Valve timing controller
Abstract
A valve timing controller has an electric motor, a control
circuit which controls the motor, a first rotor that rotates along
with a crankshaft, and a second rotor that is rotates along with a
camshaft. A phase adjusting mechanism adjusts the rotational phase
between the first rotor and the second rotor according to the
rotation of the motor. On condition that the rotating speed of the
crankshaft exceeds a threshold value, the control circuit stops the
energization of the electric motor. Thereby, the phase adjusting
mechanism varies the rotational phase to the most retard phase.
Inventors: |
Morii; Yasushi;
(Nagoya-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
39154759 |
Appl. No.: |
11/896536 |
Filed: |
September 4, 2007 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 2001/3443 20130101;
F01L 1/356 20130101; F01L 1/352 20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2006 |
JP |
2006-275513 |
Claims
1. A valve timing controller adjusting a valve timing of an intake
valve and/or an exhaust valve of an internal combustion engine,
comprising: an electric motor which rotates by energization; an
energizing control circuit which controls the energization of the
electric motor; and a phase adjusting mechanism including a first
rotor which rotates along with one of a crankshaft and a camshaft
of the internal combustion engine, and a second rotor which rotates
along with the other, the phase adjusting mechanism adjusting a
rotational phase between the first rotor and the second rotor
according to the rotation of the electric motor, wherein in a case
that a rotating speed of the internal combustion engine exceeds a
threshold value, the energizing control circuit stops the
energization of the electric motor so that the phase adjusting
mechanism varies the rotational phase to an end phase which is one
of a most retard phase and a most advance phase.
2. A valve timing controller according to claim 1, wherein the
phase adjusting mechanism varies the rotational phase to the end
phase which permits start up of the internal combustion engine when
the energizing control circuit stops the energization of the
electric motor.
3. A valve timing controller according to claim 1, wherein in a
case that the electric motor rotates in the same rotational phase
as the first rotor, the phase adjusting mechanism rotates the
second rotor in the same rotational phase as the first rotor, and
in a case that the electric motor rotates in a retard direction
relative to the first rotor, the phase adjusting mechanism rotates
the second rotor to the end phase relative to the first rotor.
4. A valve timing controller according to claim 3, further
comprising: a stopper means which stops the second rotor to the
first rotor in the end phase.
5. A valve timing controller according to claim 3, wherein the
threshold value is established lower than the rotating speed of the
internal combustion engine when assuming that the electric motor
rotates in the same rotational phase as the first rotor and in a
maximum speed.
6. A valve timing controller according to claim 5, wherein in the
phase adjusting mechanism which adjusts the rotational phase by
reducing the rotation speed of the electric motor and converting
the rotation of the electric motor into the rotation of the second
rotor, an actual reduction ratio between the electric motor and the
second rotor, and a minimum response speed of the rotation
variation of the second rotor at the time of the rotational
variation of the electric motor are established, when the rotation
speed of the electric motor changes from a rotation in which the
electric motor rotates in the same rotational phase as the first
rotor to a rotation in which the electric motor rotates in the
maximum speed, the actual reduction ratio is less than a reduction
ratio for the phase adjusting mechanism to reduce the rotation
speed of the electric motor and to vary the rotation of the second
rotor at the minimum response speed.
7. A valve timing controller according to claim 6, wherein the
actual reduction ratio is greater than a reduction ratio required
for the phase adjusting mechanism to reduce the rotation speed of
the electric motor and to rotate the second rotor against a
transmitting torque from the internal combustion engine.
8. The valve timing controller according to claim 7, wherein the
phase adjusting mechanism includes a planet gear which engages with
a gear provided at least one of the first rotor and the second
rotor, and lubricant is supplied to an engagement part of the
planet gear and the gear.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2006-275513 filed on Oct. 6, 2006, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a valve timing controller
which adjusts valve timing of an inlet valve and/or an exhaust
valve of an internal combustion engine.
BACKGROUND OF THE INVENTION
[0003] The valve timing controller varies the rotational phase
between two rotors which respectively rotate along with a
crankshaft and a camshaft to adjust the valve timing. JP-9-60509A
and JP-2005-48706A, for example, disclosure the valve timing
controller which adjusts the rotational phase between the rotors
according to the rotation of the electric motor.
[0004] In such an electric valve timing controller, the electric
motor is driven in the same phase as the rotors when holding the
rotational phase. Therefore, when the rotating speed of the
internal combustion engine increases, the rotating speed of the
electric motor also increases. Moreover, generally in the
high-rotation speed range of the engine, there are many cases where
the rotational phase of the rotor is held to the phase suitable for
the internal combustion engine. Since the electric motor is
continuously driven by high current in the high-rotation range of
the engine, there is a possibility of increasing of power
consumption and generating heat of the motor control circuit, which
may cause breakage of the circuit.
[0005] The present invention is made in view of the above matters,
and it is an object of the preset invention to provide an electric
valve timing controller which realizes valve timing suitable for
the internal combustion engine, restraining power consumption and
the malfunction.
SUMMARY OF THE INVENTION
[0006] According to the present invention, a valve timing
controller adjusting a valve timing of an intake valve and/or an
exhaust valve of an internal combustion engine, includes an
electric motor which rotates by energization, and an energizing
control circuit which controls the energization of the electric
motor. The controller further includes a phase adjusting mechanism
including a first rotor which rotates along with one of a
crankshaft and a camshaft of the internal combustion engine, and a
second rotor which rotates along with the other. The phase
adjusting mechanism adjusts a rotational phase between the first
rotor and the second rotor according to the rotation of the
electric motor. In a case that a rotating speed of the internal
combustion engine exceeds a threshold value, the energizing control
circuit stops the energization of the electric motor so that the
phase adjusting mechanism varies the rotational phase to an end
phase which is one of a most retard phase and a most advance
phase.
[0007] Since the energizing control circuit stops the energization
of the electric motor in a high rotation range of the internal
combustion engine, a power consumption of the electric motor is
reduced and a malfunction due to heat generation is restricted.
Furthermore, the energizing control circuit stops the energization
of the electric motor so that the phase adjusting mechanism varies
the rotational phase to an end phase. Hence, the end phase suitable
for an engine in high speed range can be obtained in spite of
deenergization of the electric motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a cross sectional view showing a valve timing
controller according to an embodiment of the present invention,
taken along a line I-I in FIG. 2.
[0009] FIG. 2 is a cross sectional view taken along a line II-II in
FIG. 1.
[0010] FIG. 3 is a cross sectional view taken along a line III-III
in FIG. 1.
[0011] FIG. 4 is a diagram for explaining the fluctuation
torque.
[0012] FIG. 5 is a graph for explaining actuation of the energizing
control circuit.
[0013] FIG. 6 is a graph for explaining the characteristic of the
phase adjusting mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] Hereafter, a first embodiment of the present invention is
described. FIG. 1 shows the valve timing controller 1 according to
the first embodiment of the present invention. The valve timing
controller 1 is provided in the transmission system which transmits
engine torque to the camshaft 2 from the crankshaft (not shown) of
the internal combustion engine. The valve timing controller 1
includes a torque generating system 4 and a phase adjusting
mechanism 8. In the present embodiment, the camshaft 2 opens/closes
the intake valve (not shown), and the valve timing controller 1
adjusts the valve timing of the intake valve.
[0015] First, the torque generating system 4 is explained. The
torque generating system 4 is provided with an electric motor 5 and
a control circuit 6.
[0016] The electric motor 5 is, for example, a brushless motor.
When energized, the electric motor generates controlling torque on
its motor shaft 7. The control circuit 6 includes a microcomputer
and a motor driver, and is arranged in exterior and/or interior of
the electric motor 5. The control circuit 6 is electrically
connected with the electric motor 5 to control the energization of
the electric motor 5 according to the operation condition of the
internal combustion engine.
[0017] Next, the phase adjusting mechanism 8 is explained
hereinafter. The phase adjusting mechanism 8 is provided with the
driving-side rotor 10, the driven-side rotor 20, the planetary
carrier 40, and the planet gear 50.
[0018] The driving-side rotor 10 includes a gear member 12 and a
sprocket 13 which are coaxially fixed together by a bolt. The
driving-side rotor 10 has a chamber house 11 in which the
driven-side rotor 20, the planetary carrier 40, and the planet gear
50 are accommodated. The peripheral wall part of the gear member 12
forms the driving-side internal gear 14 which has an addendum
circle inside of a dedendum circle. The sprocket 13 has a plurality
of gear teeth 16. A timing chain (not shown) is wound around the
sprocket 13 and a plurality of teeth of the crankshaft so that the
sprocket 13 is linked to the crankshaft. When the engine torque is
transmitted to the sprocket 13 through the timing chain, the
driving-side rotor 10 rotates in accordance with the crankshaft. In
the present embodiment, the driving-side rotor 10 rotates in
counterclockwise direction in FIGS. 2 and 3, and the rotating speed
of the driving-side rotor 10 is half (1/2) of the rotating speed of
the crankshaft.
[0019] As shown in FIGS. 1 and 2, the driven-side rotor 20 is
formed in cup shape, and is concentrically arranged in the sprocket
13. The peripheral wall part of the driven-side rotor 20 forms a
driven-side internal gear 22 which has an addendum circle inside of
its dedendum circle. The driven-side internal gear 22 is engaged
with an inner wall of the sprocket 13.
[0020] As shown in FIG. 1, the bottom wall part of the driven-side
rotor 20 forms the connecting part 24 which is fixed on the
camshaft 2 by a bolt. The driven-side rotor 20 is interlocked with
the camshaft 2, and performs a relative rotation with respect to
the driving-side rotor 10. Besides, in FIGS. 2 and 3, an arrow X
shows an advance direction relative to the driving-side rotor 10,
and an arrow Y shows a retard direction relative to the
driving-side rotor 10.
[0021] As shown in FIGS. 1 to 3, the planetary carrier 40 is formed
cylindrical and forms the input part 41 through which the
controlling torque is inputted from the motor shaft 7. A plurality
of engaging grooves 42 is provided for the input part 41. The
planetary carrier 40 is connected to the motor shaft 7 through a
joint 43 which engages with the engaging grooves 42. The planetary
carrier 40 rotates along with the motor shaft 7, and performs a
relative rotation with respect to the rotors 10, 20.
[0022] The planetary carrier 40 is provided with an eccentric
portion 44 relative to the gears 14, 22. The eccentric portion 44
is engaged with an inner bore 51 of the planet gear 50 through a
bearing 45.
[0023] The planet gear 50 is formed in a cylindrical shape with a
step, and is coaxially arranged to the eccentric portion 44. That
is, the planet gear 50 is eccentrically arranged with respect to
the gears 14, 22. The planet gear 50 is provided with a
driving-side external gear 52 and a driven-side external gear 54 on
its large diameter portion and a small diameter portion. The gears
52, 54 respectively have the addendum circle outside of the
dedendum circle. The driving side external-gear 52 is arranged in
such a manner as to engage with the driving-side internal gear 14.
The driven-side external gear 54 is arranged in such a manner as to
engage with the driven-side internal gear 22. The planet gear 50
rotates around a center of the eccentric portion 44 and performs a
planetary motion in a rotation direction of the eccentric portion
44.
[0024] The phase adjusting mechanism 8 is provided with a planetary
mechanism 60 of the differential-gear type which reduces the speed
of the electric motor and converts the rotation of the motor into a
rotation of the driven-side rotor 20. And the phase adjusting
mechanism 8 equipped with such a planetary mechanism 60 adjusts the
rotational phase between the rotors 10 and 20 which determine the
valve timing according to the rotation of the electric motor 5.
[0025] When the electric motor 5 adjusts the controlling torque in
such a manner that the motor shaft 7 rotates in the same phase as
the driving-side rotor 10, the planet gear 50 rotates the
driven-side rotor 20 in the same phase as the driving-side rotor 10
while maintaining the engagement position with the gears 14 and 22.
That is, since the electric motor 5 rotates along with the rotors
10 and 20, the rotational phase between the rotors 10 and 20 is not
varied, so that the valve timing is held.
[0026] When the motor shaft 7 performs relative rotating in the
advance direction X relative to the driving-side rotor 10, the
planet gear 50 performs the planetary motion so that the
driven-side rotor 20 performs relative rotating in the advance
direction X relative to the driving-side rotor 10. That is, since
the rotational phase of the driven-side rotor 20 is advanced
relative to the driving-side rotor 10, the valve timing is also
advanced.
[0027] When the motor shaft 7 performs relative rotating in the
retard direction Y relative to the driving-side rotor 10, the
planet gear 50 performs the planetary motion so that the
driven-side rotor 20 performs relative rotating in the retard
direction Y relative to the driving-side rotor 10. That is, since
the rotational phase of the driven-side rotor 20 is retarded
relative to the driving-side rotor 10, the valve timing is also
retarded.
[0028] Next, the characterizing portion of the valve timing
controller 1 is explained in detail.
(Stopper Structure)
[0029] As shown in FIGS. 1 and 2, a plurality of stopper groove
portions 70 are provided for the sprocket 13 at its inner periphery
in a circumferential direction. Moreover, the driven-side internal
gear 22 is provided with a plurality of stoppers 72 which radially
protrude along its circumferential direction. Each stopper 72 is
respectively positioned in the corresponding stopper groove portion
70, and moves in the advance direction X and the retard direction
Y. When at least one of these stoppers 72 is brought into abutment
with edges 74 and 76 of the stopper groove portion 70, the
adjustment end of the rotational phase between the rotors 10 and 20
will be decided uniquely.
[0030] Specifically, when at least one stopper 72 is contact with
the edge 74 of advance direction X, the driven-side rotor 20 is
stopped at the most advance phase relative to the driving-side
rotor 10.
[0031] Meanwhile, when at least one stopper 72 is contact with the
edge 76 of retard direction Y, the driven-side rotor 20 is stopped
at the most retard phase relative to the driving-side rotor 10.
Therefore, when the motor 5 is deenergized and the phase adjusting
mechanism 8 varies the rotational phase of the driven-side rotor 20
in the retard direction, as shown in FIG. 2, the rotational phase
reaches and is held at the most retard phase.
[0032] Here, in this embodiment, the most retard phase is
established as a start up phase which permits start up of the
internal combustion engine. So, even if the abnormalities of the
control circuit 6 arise and the electric motor 5 is deenergized
during the operation of the internal combustion engine, the
rotational phase of the driven-side rotor 20 can be varied to the
start up phase by the phase adjusting mechanism 8 for a next start
up of the internal combustion engine.
(Lubrication Structure)
[0033] As shown in FIG. 1, a plurality of supply passages 80 which
penetrate the connecting part 24 of the driven-side rotor 20 are
formed in its circumferential direction. The inlet port of each
supply passage 80 communicates with the introductory passage 3
where lubricant is introduced from the pump 9. Moreover, the outlet
of each supply passage 80 communicates to the chamber houses 11. By
this structure, the lubricant introduced during operation of the
internal combustion engine to the introductory passage 3 is
supplied to the planetary mechanism 60 through each supply passage
80, and lubrication is performed between the gear parts 22 and 54
and between the gear parts 14 and 52.
[0034] Thus, in the phase adjusting mechanism 8 equipped with the
planetary mechanism 60 to which the lubricant is supplied, when the
viscosity of the lubricant rises at the time of the low
temperature, the controlling torque required to rotate the
driven-side rotor 20 by the electric motor 5 increases. So, since
the load of the electric motor 5 becomes excessive when required
controlling torque increases according to other factors, it is not
desirable. However, as shown in FIG. 4, the fluctuation torque is
generated according to the drive reaction force of the intake valve
during engine operation. When the fluctuation torque is transmitted
to the driven-side rotor 20 from the camshaft 2 and acts on the
motor shaft 7 through the phase adjusting mechanism 8, the required
controlling torque is increased in order to rotate the driven-side
rotor 20.
[0035] So, in the phase adjusting mechanism 8, the actual reduction
ratio Rr between the motor shaft 7 and the driven-side rotor 20
expressed by the following formula (1) is established so that the
required controlling torque due to the fluctuation torque is S % or
less of the required controlling torque due to increment of
viscosity. Besides, in the formula (1), Z1, Z2, Z3, and Z4 express
the number of teeth of each gear parts 14, 22, 52, and 54,
respectively.
Rr=(Z2/Z4Z3/Z1)/(Z2/Z4Z3/Z1-1) (1)
[0036] Specifically, the required controlling torque due to the
viscosity increment is denoted by Tc, the average torque of the
fluctuation torque in the camshaft 2 is denoted by Tv (refer to
FIG. 4), and the torque transmission efficiency from the
driven-side rotor 20 to the motor shaft 7 is defined as E %. And
the reduction ratio RI, which is required to rotate the driven-side
rotor 20 against the average torque Tv of the fluctuation torque
and to realize S %, is computed according to the following formula
(2), and the actual reduction ratio Rr is established as the value
more than the required reduction ratio RI. For example, in a case
that Tc=0.4 Nm, Tv=3 Nm, E=60%, and S=5%, since it is computed that
RI=90, the actual reduction ratio Rr is established greater than or
equal to 90 (Rr.gtoreq.90). Therefore, according to such a
configuration, the load of the electric motor 5 can be reduced.
RI=(Tv-E)/(Tc-S) (2)
(Energization Control)
[0037] As shown in FIG. 1, the rotation sensor 90 which detects the
rotation of the crankshaft of the internal combustion engine is
electrically connected to the energizing control circuit 6. The
energizing control circuit 6 deduces the rotating speed of the
crankshaft from the detection signal supplied from this rotation
sensor 90 successively, and uses it for the energization control of
the electric motor 5. And as shown in FIG. 5, the energizing
control circuit 6 stops the energization of the electric motor 5
compulsorily and makes the current the zero value in the high
rotation range Wh where the rotating speed of the crankshaft exceed
the threshold value Nth. Thereby, the rotational phase between the
rotors 10 and 20 is varied to the most retard phase.
[0038] Here, the most retard phase is established also as a phase
which is suitable for the internal combustion engine of the high
rotation numerical Wh in the point of the engine output as well as
the start up phase. When the electric motor 5 is deenergized, the
rotors 10, 20 are automatically held at the most retard phase. Some
useless power consumptions and the malfunctions due to heat
generation of the energizing control circuit 6 are restrained, and
the output of the internal combustion engine improves.
[0039] As long as the desired output of the engine is obtained in
the high rotation range Wh, the threshold value Nth is lower than a
predetermined speed Na (refer to FIG. 5) in which the electric
motor 5 rotates in the same phase as the rotors 10, at the maximum
rotation speed Mm. In a middle-low rotation range Wml, the rotation
speed of the electric motor 5 is always lower than the maximum
rotation speed Mm when the electric motor 5 rotates in the same
phase as the rotors 10, 20. Thus, it can be avoided that the
rotation speed of the electric motor 5 runs short and the electric
motor 5 does not rotate in the same phase as the rotors 10, 20.
Besides, the maximum engine speed Mm of the electric motor 5 may be
established previously in mechanism as a specification of the motor
itself, or may be realized by the energizing control circuit 6 in
control.
[0040] The predetermined speed Na of the crankshaft, which is
determined according to the engine condition, is higher than the
threshold Nth. Hence, the maximum rotation speed Mm of the electric
motor 5 can be established as low as possible, so that a small size
electric motor 5 can be used.
[0041] However, when the maximum rotation speed Mm of the electric
motor 5 becomes low excessively, there is a possibility that the
responsibility of the phase adjusting mechanism 8 may be
deteriorated. So, in the phase adjusting mechanism 8, the actual
reduction ratio Rr is established so that minimum response speed
.omega. as a response speed of the rotational variation of the
driven-side rotor 20 at the time of the rotational variation of the
electric motor 5 can be realized with the maximum speed Mm of the
electric motor 5. Besides, in the present embodiment, the minimum
response speed .omega. is expressed as relative rotating angular
velocity of the driven-side rotor 20 relative to the driving-side
rotor 10 at the time of the rotational variation of the electric
motor 5 in order to change the rotational phase between the rotors
10 and 20.
[0042] When the rotation of the electric motor 5 changes from the
same phase as the driving-side rotor 10 to the maximum speed Mm,
specifically, the deviation (=Mm-Ms) of the maximum speed Mm from
the rotating speed Ms shows linear relation with respect to the
rotating speed of the crankshaft, as shown in FIG. 6. In order to
realize the minimum response speed .omega. at the time when a
preset speed Mss (crankshaft speed is denoted by Nss in FIG. 6) is
varied to the maximum rotation speed Mm, the required reduction
speed ratio Rh is calculated according to the following formula (3)
and the actual reduction speed ratio Rr is established. For
example, in a case that Mm=3000 rpm, Mss=1000 rpm and .omega.=100
CA, since Mm-Mss=2000 rpm/60 s720 CA and Rh=240, the actual
reduction ratio Rr which fills Rh.ltoreq.240 is established.
Therefore, according to such a configuration, even if the maximum
speed Mm of the electric motor 5 becomes low, the minimum response
speed .omega. required for the phase adjusting mechanism 8 is fully
assured. Besides, "CA" is the unit showing the rotation angle of
the camshaft 2 in which the rotating speed serves as half of the
crankshaft.
Rh=(Mm-Mss)/.omega. (3)
Other Embodiments
[0043] The present invention is not limited to the embodiment
mentioned above, and can be applied to various embodiments.
[0044] The energizing control circuit 6 stops the energization to
the electric motor 5, when the crankshaft rotating speed exceeds
the threshold value Nth and both other conditions are satisfied.
Alternatively, when the crankshaft rotating speed exceeds the
threshold value Nth and the other conditions are not satisfied, the
adjustment of the control torque may be continued without
deenergizing the electric motor 5. Moreover, the energizing control
circuit 6 may utilizes the rotation speed of the camshaft 2 in
place of or in addition to the crankshaft rotating speed in
controlling the energization of the electric motor 5, especially
the energization control on condition of the threshold value. In a
case that the rotation speed of camshaft 2 is utilized to control
the energization of the motor 5, the threshold value Nth is set as
half value of the threshold of the crankshaft speed.
[0045] The rotor 10 may perform the interlocking rotation with the
camshaft 2, and the rotor 20 may perform the interlocking rotation
with the crankshaft. Moreover, when the motor 5 is deenergized, the
rotational phase between the rotors 10 and 20 may be brought to the
most advance phase. The phase adjusting mechanism 8 may be a
structure in which the planet gear is engaged with the gear
provided in one of the rotors.
[0046] At least one of the gears 14 and 22 and corresponding gears
52, 54 may be changed into the external gear and the internal gear,
respectively. Moreover, the lubrication fluid supplied to the
planetary mechanism part 60 can be other than a lubricant for the
internal combustion engines.
[0047] The stopper structure which stops the rotor 20 to the rotor
10 may be another structure other than the combination of the slot
70 and the projected part 72.
[0048] And the present invention is applicable also to the
apparatus which adjusts the valve timing of the exhaust valve, and
the apparatus which adjusts the valve timing of the intake valve
and the exhaust valve.
* * * * *