U.S. patent application number 10/809706 was filed with the patent office on 2004-09-30 for variable valve timing controller.
This patent application is currently assigned to DENSO CORPORATION & NIPPON SOKEN, INC.. Invention is credited to Inohara, Takayuki, Takenaka, Akihiko, Tani, Hideji, Urushihata, Haruyuki, Yoshida, Hideji.
Application Number | 20040187819 10/809706 |
Document ID | / |
Family ID | 32993067 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040187819 |
Kind Code |
A1 |
Takenaka, Akihiko ; et
al. |
September 30, 2004 |
VARIABLE VALVE TIMING CONTROLLER
Abstract
The variable valve timing controller controls the valve timing
of the intake valve. The variable valve timing controller has a
shaft, the stator fixed on the engine and generating the magnetic
field around the shaft and rotational phase converter converting
the torque applied to the shaft. When the valve timing is in the
most delayed timing, the engine can be started. The rotational
phase of this timing is called the feasible phase. When the stator
stops generating the magnetic field, the load torque arise on the
shaft. The rotational phase converter varies the rotational phase
into the feasible phase with receiving the load torque from the
shaft.
Inventors: |
Takenaka, Akihiko;
(Anjo-city, JP) ; Urushihata, Haruyuki;
(Chiryu-city, JP) ; Tani, Hideji; (Hashima-gun,
JP) ; Yoshida, Hideji; (Hashima-city, JP) ;
Inohara, Takayuki; (Okazaki-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Assignee: |
DENSO CORPORATION & NIPPON
SOKEN, INC.
Aichi-pref.
JP
|
Family ID: |
32993067 |
Appl. No.: |
10/809706 |
Filed: |
March 26, 2004 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 1/352 20130101;
F01L 2800/01 20130101; F01L 1/022 20130101; F01L 1/024
20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2003 |
JP |
2003-92126 |
Nov 18, 2003 |
JP |
2003-388000 |
Claims
What is claimed is:
1. A variable valve timing controller for an internal combustion
engine, the variable valve timing controller being disposed in a
system in which the torque of a driving shaft is transmitted to a
driven shaft adjusting an opening and closing timing of an intake
valve and/or an exhaust valves, comprising: a rotary shaft
connected with a driving shaft; a stator applying a torque to the
rotary shaft by generating a magnetic field around the rotary
shaft, the stator fixed relatively to the internal combustion
engine; and a rotational phase converter converting the rotational
phase of the driven shaft relatively to the driving shaft; wherein
when the stator stops forming the electro magnetic field, the load
torque arises on rotary shaft, and the rotational phase converter
converts the rotational phase of the driven shaft toward a feasible
phase in a safety direction with receiving the load torque, the
feasible phase in which the internal combustion engine can be
started.
2. The variable valve timing controller for an internal combustion
engine according to claim 1, further comprising: a bearing
supporting the driven shaft rotatively.
3. The variable valve timing controller for an internal combustion
engine according to claim 1, wherein the driving shaft has a magnet
on the outer surface thereof, and the stator has a coil which forms
the magnetic field around the driving shaft with being fed the
current.
4. The variable valve timing controller for an internal combustion
engine according to the claim 3, further comprising: a driving
circuit which is connected with a terminal of the coil and feeds a
current to the coil, the driving circuit making an electrical short
among the terminals when the coil stops generating the magnetic
field.
5. The variable valve timing controller for an internal combustion
engine according to claim 1, further comprising: a control circuit;
and a driving circuit which is electrically connected with the
stator and the control circuit and feeds the current to the stator
according to a signal received from the control circuit, wherein
the driving circuit applies a control torque to the rotational
shaft by self-controlling the feeding of current when the control
signal from the control circuit is not input to the driving
circuit, and the rotational phase converter varies the rotational
phase of the driven shaft into a safety phase with receiving the
control torque from the rotational shaft.
6. A variable valve timing controller for an internal combustion
engine, the variable valve timing controller being disposed in a
system in which the torque of a driving shaft is transmitted to a
driven shaft adjusting an opening and closing timing of an intake
valve and/or an exhaust valves, comprising: a rotary shaft
connected with a driving shaft; a stator applying a torque to the
rotary shaft by generating a magnetic field around the rotary
shaft, the stator fixed relatively to the internal combustion
engine; and a rotational phase converter converting the rotational
phase of the driven shaft relatively to the driving shaft; a
control circuit; a driving circuit which is electrically connected
with the stator and the control circuit and feeds the current to
the stator according to a signal received from the control circuit,
wherein the driving circuit applies a control torque to the
rotational shaft by self-controlling the feeding of current when
the control signal from the control circuit is not input to the
driving circuit, and the rotational phase converter varies the
rotational phase of the driven shaft into a feasible phase in a
safety direction with receiving the control torque from the
rotational shaft.
7. The variable valve timing controller for an internal combustion
engine according to one of claim 1, wherein the safety direction is
a delay direction.
8. The variable valve timing controller for an internal combustion
engine according to one of claim 1, wherein the safety direction is
an advance direction.
9. The variable valve timing controller for an internal combustion
engine according to one of claim 1, wherein the rotational phase
converter has a driving rotational member rotating with the driving
shaft, a driven member rotating with the driven shaft and a
transmitting rotational member, the rotational phase converter
varying the rotational phase by converting the relative rotational
movement of the transmitting rotational member against the driving
rotational member into the relative rotational movement of the
driven member against the driving rotational member
10. The variable valve timing controller according to claim 9,
wherein the rotational phase converter has a biasing member for
biasing the driven member, and a biasing direction is the relative
rotating direction of the driven member in the safety
direction.
11. The variable valve timing controller according to claim 9,
wherein the rotational phase converter has a biasing member for
biasing the driven member, and a biasing direction is reverse to
the relative rotating direction of the driven member in the safety
direction.
12. The variable valve timing controller according to claim 11,
wherein the rotational phase converter has an interrupt means for
interrupt the operation of the biasing force to the driven member
when the rotational phase changes into the safety direction.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2003-92126 filed on Mar. 28, 2003 and Japanese Patent Application
No. 2003-388000 filed on Nov. 18, 2003, the disclosure of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a variable valve timing
controller that changes opening and timing of intake valves and/or
exhaust valves of an internal combustion engine according to
operating condition of the engine. The opening and closing timing
is referred to as valve timing, the variable valve timing
controller is referred to as the VVT controller, and the internal
combustion engine is referred to as an engine hereinafter.
BACKGROUND OF THE INVENTION
[0003] The VVT controller is disposed in a torque transfer system
which transfers the torque of the driving shaft of the engine to
the driven shaft which opens and closes at least one of an intake
valve or an exhaust valve. The VVT controller adjusts the valve
timing of the valves by varying a rotational phase of the driven
shaft to the driving shaft.
[0004] One of the conventional VVT controller varies the rotational
phase by oil pressure. In such a VVT controller, it may be
difficult to precisely control the oil pressure when it is under
the sever condition such as low temperature and just after engine
starting.
[0005] JP-U-4-105906 shows a VVT controller which varies the
rotational phase of the driven shaft against the driving shaft by
an electric motor. A stator of the electric motor makes a magnetic
field which applies a torque to a motor shaft, and the torque is
transmitted to a planetary gear mechanism to vary the rotational
phase.
[0006] In this type of the VVT controller, when the magnetic field
is not formed due to the electrical shorting or break of the stator
coil, it is impossible to control the rotational phase by the
planetary gear mechanism. Thus the rotational phase of the driven
shaft may shift to the phase wherein it is impossible to start the
engine.
SUMMARY OF THE INVENTION
[0007] The present invention is made in view of the above matters,
and it is an object of the present invention to provide the VVT
controller which can start the engine even in case of trouble.
[0008] If the stator fails to form magnetic field, a resistant
torque arises on the motor shaft. Receiving the resistant torque, a
phase converter shifts the rotational phase of the driven shaft
toward the safety phase in which the engine can be started. Thus,
even if the magnetic field is not formed due to the electrical
shorting or break of the stator coil, the phase shift from the
phase wherein the engine can be started into the phase wherein the
engine can not be started is prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Other objects, features and advantages of the present
invention will become more apparent from the following detailed
description made with reference to the accompanying drawings, in
which like parts are designated by like reference numbers and in
which:
[0010] FIG. 1 is a characteristic diagram for explaining the
function of the VVT controller;
[0011] FIG. 2 is a cross sectional view of the VVT controller along
a line II-II in FIG. 3 according to the first embodiment;
[0012] FIG. 3 is a cross sectional view of VVT controller along a
line III-III in FIG. 2 for explaining an operation according to the
first embodiment;
[0013] FIG. 4 is a cross sectional view of VVT controller along a
line III-III in FIG. 2 for explaining the other operation according
to the first embodiment;
[0014] FIG. 5 is a cross sectional view of VVT controller along a
line III-III in FIG. 2 for explaining the other operation according
to the first embodiment;
[0015] FIG. 6 is a cross sectional view of VVT controller along
line VI-VI in FIG. 2;
[0016] FIG. 7 is a cross sectional view of VVT controller along
line VII-VII in FIG. 2;
[0017] FIG. 8 is a circuit diagram showing a stator, a driving
circuit and a control circuit of the VVT controller according to
the first embodiment;
[0018] FIG. 9 is an enlarged view of essential part of FIG. 2;
[0019] FIG. 10 is a side view of a transmitting member of the VVT
controller along a line X-X of FIG. 2;
[0020] FIG. 11 is a characteristic diagram for explaining the
function of the VVT controller according to the second
embodiment;
[0021] FIG. 12 is a cross sectional view of the VVT controller
along a line III-III in FIG. 2 according to the second
embodiment;
[0022] FIG. 13 is a cross sectional view of VVT controller along a
line III-III in FIG. 2 for explaining an operation according to the
second embodiment;
[0023] FIG. 14 is a circuit diagram showing a stator, a driving
circuit and a control circuit of the VVT controller according to
the third embodiment;
[0024] FIG. 15 is a cross sectional view of the VVT controller
along a line III-III in FIG. 2 for explaining an operation
according to the fourth embodiment;
[0025] FIG. 16 is a characteristic diagram for explaining the
function of the VVT controller according to the fifth
embodiment;
[0026] FIG. 17 is a cross sectional view of the VVT controller
along a line III-III in FIG. 2 for explaining an operation
according to the fifth embodiment;
[0027] FIG. 18 is a cross sectional view of the VVT controller
along a line III-III in FIG. 2 for explaining the other operation
according to the fifth embodiment;
[0028] FIG. 19 is a cross sectional view of the VVT controller
along a line III-III in FIG. 2 for explaining the other operation
according to the fifth embodiment.
DETAILED DESCRIPTION OF EMBODIMENT
(First Embodiment)
[0029] FIG. 2 shows a VVT controller according to the first
embodiment of the present invention. The VVT controller 10 is
disposed in a torque transfer system which transfers the torque of
a crankshaft as a driving shaft of the engine to a cam shaft 4 as a
driven shaft which opens and closes at least one of an intake valve
or an exhaust valve. The VVT controller 10 adjusts the valve timing
of intake valve by varying the rotational phase of the cam shaft 4
as shown by an arrow 200 in FIG. 1.
[0030] As shown in FIGS. 2 and 3, a sprocket 11 as a driving
rotator is provided with a supporting portion 12, a input portion
13 having a larger diameter than that of the supporting portion 12,
and a first converting portion 14 connecting the supporting portion
12 with the input portion 13. The supporting portion 12 is
rotatively supported by the cam shaft 4 and output shaft 16 around
a center axis O. A chain belt (not shown) runs over a plurality of
gear tooth 13a formed on the input portion 13 and a plurality of
gear tooth formed on the crank shaft (not shown). When the torque
is transmitted from the crank shaft to the input portion 13 through
a chain belt, the sprocket 11 rotates clockwise around the center
axis O with keeping the rotational phase to the crankshaft. The
sprocket 11 rotates in synchronism with the rotation of the
crankshaft.
[0031] The output shaft 16 as the driven shaft has a fixed portion
17 and converting portion 18. One end of the cam shaft 4 is
concentrically coupled to the fixed portion 17 by a bolt, and the
output shaft 16 rotates around the center axis O with keeping the
rotational phase to the cam shaft 4. That is, the output shaft 16
rotates in synchronism with the rotation of the cam shaft 4. A
second converting portion 18, a planetary gear 23 and a transfer
member 24 are sandwiched between a cover 15 and the first
converting portion 14. The second converting portion 18 keeps
contact with the inner surface 14a of the first converting portion
14 and confronts the outer surface 24a of the transfer member 24
with a clearance. A control member 50 is connected with the first
converting portion 14 and the second converting portion 18. The
output shaft 16 rotates clockwise in FIG. 3 via the control member
50 as well as the sprocket 11 rotates with the crankshaft. The
output shaft 16 can rotate in advance direction X and delay
direction Y in FIG. 3.
[0032] FIG. 3 shows the cam shaft 4 is in the most delayed
position, FIG. 4 shows the cam shaft 4 is in the most advanced
position, and FIG. 5 shows the cam shaft 4 is in the middle
position relative to the sprocket 11 and the crankshaft. The cam
shaft 4 positioning the most delayed phase, the valve timing of the
intake valve is the most delayed phase as shown by the dashed line
in FIG. 1 so that the engine can be started. The most delayed phase
in this embodiment corresponds to the feasible phase. On the other
hand, the cam shaft 4 positioning the most advanced phase, the
valve timing of the intake valve is the most advanced phase as
shown by the solid line in FIG. 1 so that the engine can not be
started.
[0033] An electric motor 30 is a three-phase motor and comprised of
a housing 31, a bearing 32, a motor shaft 33, a stator 34, a
driving circuit 35 and the control circuit 36. The housing 31 is
fixed on the engine through a stay 37 as shown in FIG. 2 and FIG.
6. The housing 31 is provided with a pair of bearing 32.
[0034] A motor shaft 33 is supported by the pair of bearing 32 and
rotates around the center axis O. The motor shaft 33 is connected
with an eccentric shaft 25 through a joint 38 so that the motor
shaft 33 rotates clockwise with the eccentric shaft 25 in FIG. 6
and FIG. 7. The motor shaft 33 has a shaft body 33a and a
disk-shaped rotor 33b. A plurality of magnets 39 are disposed in
the rotor 33b near the outer periphery. The magnets 39 are made
from rare-earth magnets and are disposed with same pitch around the
center axis O. Adjacent magnets are disposed respectively in such a
manner that a magnetic pole of the outer surface is reverse to each
other.
[0035] The stator 34 is fixed on the engine through the housing 31
and the stay 37 at the outer side of the motor shaft 33. The stator
34 has a cylindrical body 40, a core 41 and a coil 42. The core 41
are formed by stacking a plurality of iron plates and protrudes
toward the motor shaft 33 from the inner surface of the body 40.
The core 41 has twelve protrusions in same pitch, the coil 42 is
wound on each protrusions. As shown in FIG. 8 schematically, the
coil 42 is connected in Y-connection and has three terminals
42u,42v,42w.
[0036] A driving circuit 35 is a bride circuit as shown in FIG. 8
and has six transistors as switching elements. The collector of the
transistors are connected with an electric main power 45, and the
emitter of the transistors are grounded. The emitter of the
transistor 44a and the collector of the transistor 44d are
connected with the terminal 42u via a lead 46r, the emitter of the
transistor 44b and the collector of the transistor 44e is connected
with the terminal 42v through a lead 46s, and the emitter of the
transistor 44c and the collector of the transistor 44f is connected
with the terminal 42w. The base of the transistor
47a,47b,47c,47d,47e,47f are connected with a control circuit
36.
[0037] The control circuit 36 has a microcomputer and detects the
condition of the VVT controller 10 base on the signals such as the
current value of the driving circuit 35 and the rotation angle of
the motor shaft 33.
[0038] If there is no problem in the VVT controller, the control
circuit 36 varies the current value which is fed to the base of the
transistor 44a-44f. The transistor 44a-44f is turned on or turned
off in a sequence according to the variation of the current fed to
the bases thereof. The sequence of on-off of transistor 44a-44f is
controlled by the control circuit 36 in an order or in inverse
order. When the current is fed to the coil 42 via the terminal
42u,42v,42w in this order, the magnetic field is formed clockwise
around the motor shaft 33. In this magnetic field, since the
magnets 39 receive the attract force and repel force, the torque in
advance direction X is applied to the motor shaft 39. When the
current is fed to the coil 42 via the terminal 42u,42v,42w in
inverse order, the magnetic field is formed anti-clockwise around
the motor shaft 33. In this magnetic field, since the magnets 39
receive the attract force and repel force, the torque in delay
direction Y is applied to the motor shaft 39.
[0039] The driving motor shaft 33 receives a friction torque in
delay direction Y due to the friction between the motor shaft 33
and the bearings 32. The driving motor shaft 33 generates a counter
electromotive force by the interaction between the magnets 39 and
the coil 42 and receives the breaking torque in delay direction Y
corresponding to the counter electromotive force by the
interaction. In case of keeping the torque constant, the control
circuit 36 controls the current fed to the coil 42 so that the
torque in advance direction X is applied to the motor shaft 33, the
torque canceling the friction torque and the breaking torque. In
case of increasing the torque in advance direction or in delay
direction, the control circuit 36 controls the current fed to the
coil 42 with reflecting the friction torque and the breaking
torque.
[0040] If at least one of the lead 46r-46t causes an electrical
shorting or a break, the control circuit 36 turn of the transistors
44a,44b,44c and turn on the transistors 44d,44e,44f by controlling
the input current fed to the transistors 44a-44f. Thereby, the
driving circuit 35 forms a short- loop with causing an electrical
shorting among the terminals 42u,42v,42w.
[0041] A reduction gearing 20 is comprised of a ring gear 22, the
eccentric shaft 25, the planetary gear 23 and the transfer member
24. The ring gear 22 is fixed on the inner surface of the input
portion 13. The ring gear 22 is an internal gear of which an
addendum circle is inside of a dedendum circle. The ring gear 22
rotates clockwise around the center axis O in FIG. 7 with the
sprocket 11.
[0042] The eccentric shaft 25 is connected with the motor shaft 33
of the electric motor 30 so that the eccentric shaft 25 is offset
against the center shaft O. In FIG. 7, "P" represents an axis of
the eccentric shaft 25 and "e" represents an eccentric amount of
the eccentric shaft 25 relative to the center shaft O.
[0043] The planetary gear 23 is comprised of an external gear of
which an addendum circle is outside of a dedendum circle. A
curvature of the addendum circle of the planetary gear 23 is
smaller than that of the dedendum circlet of the ring gear 22. The
planetary gear 23 has one more tooth than the ring gear 22. The
planetary gear 23 is located inside of the ring gear 23 with
engaging a part of teeth of the planetary gear 23 with a part of
teeth of the ring gear 22. The planetary gear 23 has an circular
engage hole 23 on the same axis. One end of the eccentric shaft 25
is inserted into the circular engage hole 23 through a bearing (not
shown). The planetary gear 23 is supported by an outer surface of
the eccentric shaft 25 so that the planetary gear 23 can rotate
relatively to the eccentric axis P. Thereby, the eccentric shaft 25
can rotate in advance direction X or in delay direction Y relative
to the sprocket 11.
[0044] The transfer member 24 as an transfer rotor is formed like a
circular plate and is supported by the inner surface of the input
portion 13 so that the transfer member 24 rotates around the center
axis O relatively. The transfer member 24 has nine engage holes 26
which are arranged in same pitch around the center axis O. The
engage holes have a circular shape and confront the outer surface
24b of the transfer member 24 which keeps in touch with the
planetary gear 23. Engage projections 27 are formed in nine places
which face each engage holes 26 at outer surface 23a of the
planetary gear 23 which touches the transfer member 24. Each engage
projection 27 is formed in the circumference of the eccentric axis
P of the eccentric shaft 25 at equal intervals. Each engage
projection 27 is cylindrical shape and engages with the engage
holes 26. The diameter of the engage projection 27 is smaller than
the inner diameter of the engage holes 26. The control member 50 is
connected with the outer surface 24a of the transfer member 24 in a
second converting portion side.
[0045] While the friction torque and the breaking torque are
constant, and when the torque applied to the motor shaft 33 and
transmitted to the eccentric shaft 25 is constant, the planetary
gear 23 does not rotate relative to the eccentric shaft 25.
Thereby, the planetary gear 23 engages the ring gear 22 and rotates
with the sprocket 11, the eccentric shaft 25 and the motor shaft 33
with keeping the rotational phase constant relative to the ring
gear 22. The engage projection 27 presses the inner surface of the
engage hole 26 in a rotational direction (advance direction X in
this case), and the transfer member 24 rotates clockwise around the
center axis O in FIG. 7 with keeping the rotational phase constant
relative to the sprocket 11. The period when the friction torque
and the breaking torque do not change substantially is referred to
as invariable period.
[0046] During the invariable period, when the torque applied to the
motor shaft 33 increases in the delay direction Y, the planetary
gear 23 rotates relatively in the advance direction X to the
eccentric shaft 25 with being pressed by the outer surface of the
eccentric shaft 25 and with receiving the function of the ring gear
22. The planetary gear 23 rotates in the advance direction relative
to the sprocket 11 with engaging with the ring gear 23 partially.
Since the forth in which the engage projection 27 presses the
engage hole 26 in the advance direction increases, the transfer
member 24 rotates relatively in the advance direction X to the
sprocket 11. As described above, the reduction gearing 20 transmits
the amount of torque changed to the transfer member 24 while
changing the direction into the advance direction X and increasing
the amount of the torque applied to the motor shaft 33.
[0047] During the invariable period, when the torque applied to the
motor shaft 33 increases in the advance direction X, the planetary
gear 23 rotates relatively in the delay direction Y to the
eccentric shaft 25 with being pressed by the outer surface of the
eccentric shaft 25 and with receiving the function of the ring gear
22. The planetary gear 23 rotates relatively in the delay direction
Y to the sprocket 11 with engaging with the ring gear 23 partially.
Since the forth in which the engage projection 27 presses the
engage hole 26 in the advance direction increases, the transfer
member 24 rotates relatively in the advance direction X to the
sprocket 11. As described above, the reduction gearing 20 transmits
the amount of torque changed to the transfer member 24 while
changing the direction into the delay direction Y and increasing
the amount of the torque applied to the motor shaft 33.
[0048] A conventional reduction gearing can be used instead of the
reduction gearing 20 of the present embodiment. The torque applied
to the motor shaft 33 can be transmitted to the transfer member 24
directly.
[0049] A phase converter is comprised of the transfer member 24,
the first converting portion 14 and the second converting portion
18, which are connected with each other. The phase converter varies
the rotational phase of the cam shaft 4 relatively to the
crankshaft by converting the relative rotational movement of the
transfer member 24 against the sprocket 11 into the relative
rotational movement into the relative rotational movement of the
output shaft 19 against the sprocket 11. Referring to FIGS. 2-5,
FIG. 9 and FIG. 10, the structure of the phase converter is
described herein after. In FIG. 3-5, a hatching is omitted.
[0050] As shown in FIG. 3, the first converting portion 14 is a
circular plate which is vertical to the center axis O and has three
holes 60. Each of the holes 60 is formed in 120 degrees interval.
As shown in FIG. 3 and FIG. 9, the holes 60 are opened at the inner
surface 14a of the first converter 14 which is contacting with the
second converter 18. Inner surfaces of the holes 60 form the
trajectories 62 through which the control member 50 passes. The
trajectories 62 inclined against the first converter 14 such that
the radial distance from the center axis O varies. In this
embodiment, the trajectories 62 are straight lines inclined into
the delay direction Y with departing from the center axis O.
[0051] As shown in FIG. 3, the second converting portion 18 is a
plate shaped like triangle which is vertical to the center axis O,
and have three holes 70 confronting to the holes 60 of the first
converting portion 14. Each of holes 70 is formed near the three
apexes of the second converting portion 18 in 120 degrees interval.
As shown in FIG. 3 and FIG. 9, the holes 70 penetrate the second
converting portion 18 in the thickness thereof and confront the
outer surface 18a and outer surface 18b. The holes 70 form
trajectories 62 by the inner surface thereof, through which the
control member 50 passes by the inner surface thereof. The
trajectories 72 are inclined against the radial axis of the second
converting portion 18 with varying the distance from the center
axis O. In this embodiment, the trajectories 72 are straight lines
inclined into the delay direction Y with departing from the center
axis O. Thereby, the trajectories 72 of the holes 70 and the
trajectories 62 of the holes 60 cross each other at the place
corresponding to the rotational phase of the output shaft 19
relative to the sprocket 11.
[0052] As shown in FIG. 3, the control member 50 is disposed at the
three places corresponding to three of the holes 60,70. As shown in
FIG. 2, FIG. 3 and FIG. 9, the control members 50 are cylindrical
shape, and sandwiched between the first converting portion 14 and
the transfer member 24 passing through cross points of the
trajectories 62 and the trajectories 72. The control members 50
contact the inner side surfaces 60a and 60b of the holes 60 and
also contact the side inner surfaces 70a and 70b of the holes
70.
[0053] As shown in FIG. 10, the transfer member 24 has three holes
80 which are formed in 120 degree interval around the center axis O
As shown in FIG. 9 and FIG. 10, the holes 80 are opened at the
outer surface 24a of the transfer member 24 confronting the second
converting portion 18. The inner surface of the holes 80 form
trajectories 80 respectively through which the control member 50
passes. The trajectories 82 is inclined against the radial axis of
the transfer member 24 such that the radial distance from the
center axis O varies. In this embodiment, the trajectories 82 is
eccentric to the center axis O and is arc shaped, which are
inclined in the advance direction X as departing from the center
axis O and cross the trajectories 62, 72. In each of the trajectory
82, the control member 50 is inserted. The control member 50 is
contact with the inner side surfaces 80a and 80b.
[0054] When the transfer member 24 keeps the rotational phase
constant, the control member 50 stays in the trajectory 82 and
rotates with the transfer member 24. The control member 50 stays
also in the trajectories 62,72, and transmits the input torque from
the sprocket 11 to the output shaft 16.
[0055] When the transfer member 24 rotates relatively in the
advance direction X to the sprocket 11, the control member 50 is
pressed by the side surface 80b extending radial outside of the
trajectory 82. The control member 50 moves in the delay direction Y
toward the center of the transfer member 24 and makes the radial
distance from the center axis O (referred to as the radial distance
herein after) short. At the same time, the control member 50
presses the side surface 60a of the trajectory 62 in the advance
direction X and presses the side surface 70b in the delay direction
Y. Thereby, the control member 50 passing in the trajectory 62,72,
the output shaft 16 rotates relatively in the delay direction Y to
the sprocket 11.
[0056] When the transfer member 24 rotates relatively in the delay
direction Y, the control member 50 is pressed by the side surface
80a extending radial inside of the trajectory 82. The control
member 50 moves in the advance direction X toward the peripheral of
the transfer member 24 and makes the radial distance long. At the
same time, the control member 50 presses the side surface 60b of
the trajectory 62 in the delay direction Y and presses the side
surface 70a in the advance direction X. Thereby, the control member
50 passing in the trajectory 62,72, the output shaft 16 rotates
relatively in the advance direction X to the sprocket 11.
[0057] The operation of the VVT controller is described herein
after.
[0058] (First Operation)
[0059] When the rotational phase of the cam shaft 4 relative to the
crankshaft is unchanged during the invariable period, the control
circuit 36 controls the current fed to the stator 34 from the
driving circuit 35 so that the applied torque to the motor shaft 33
is kept constant. Since the relative rotation of the transfer
member 24 to the sprocket 11 does not occur, the relative rotation
of the output shaft 16 to the sprocket 11 does not occur.
Therefore, the rotational phase of the cam shaft 4 against the
crankshaft is kept constant.
[0060] (Second Operation)
[0061] When the rotational phase of the cam shaft 4 relative to the
crankshaft is delayed during the invariable period, the control
circuit 36 controls the current fed to the stator 34 from the
driving circuit 35 so that the applied torque to the motor shaft 33
is increased in the delay direction. The increased torque is
altered the direction thereof by the reduction gearing 20 and
transmitted to the transfer member 24, thus the transfer member 24
rotates relatively in the advance direction X to the sprocket 11.
The radial distance of the control member 50 becomes short, and the
output shaft 16 rotates relatively in the delay direction Y to the
sprocket 11. The rotational phase of the cam shaft 4 against the
crankshaft is altered toward the delay direction.
[0062] (Third Operation)
[0063] When the rotational phase of the cam shaft 4 relative to the
crankshaft is advanced during the invariable period, the control
circuit 36 controls the current fed to the stator 34 from the
driving circuit 35 so that the applied torque to the motor shaft 33
is increased in the advance direction. The increased torque is
altered the direction thereof by the reduction gearing 20 and
transmitted to the transfer member 24, thus the transfer member 24
rotates relatively in the delay direction Y to the sprocket 11. The
radial distance of the control member 50 becomes long, and the
output shaft 16 rotates relatively in the advance direction X to
the sprocket 11. The rotational phase of the cam shaft 4 against
the crankshaft is altered toward the advance direction.
[0064] (Fourth Operation)
[0065] When a electrical break or shorting arises in one of the
leads 46r-46t in the first operation through the third operation,
the current supply to the corresponding coil 42 is stopped. The
control circuit 36 controls the driving circuit 35 such that
electrical shorts arise among the terminal 42u,42v,42w, the current
supply to the remaining coils 42 is stopped. The rotating magnetic
field around each of the coils 42 is ceased, the electrical
resistance among the terminal 42u,42v,42w decrease rapidly, and the
counter-electromotive force generated by the coils 42 increases.
The breaking torque arose by the counter-electromotive force and
the friction torque between the motor shaft 33 and the bearing 32
are applied to the motor shaft 33 as a load torque. The load torque
is altered the direction thereof and transmitted to the transfer
member 24. Thus the transfer member 24 and the output shaft 16
rotate relatively in the advance direction X and the delay
direction Y to the sprocket 11, the rotational phase of the cam
shaft 4 against the crankshaft is changed to the delay direction.
In this embodiment, that is, the rotational phase of the cam shaft
varies from the most advanced position in which the engine can not
be started to the most delayed position in which the engine can be
started in the more safety direction. Thereby the changes of the
rotational phase into the most advanced position in which the
engine can not be started is prevented.
(Second Embodiment)
[0066] The VVT controller of the second embodiment adjusts the
valve timing of intake valve by varying the rotational phase of the
cam shaft 4 as shown by an arrow 201 in FIG. 11.
[0067] FIG. 12 shows the cam shaft 4 is in the most advanced
position, FIG. 13 shows the cam shaft 4 is in the most delayed
position relative to the sprocket 11 and the crankshaft. The cam
shaft 4 positioning the most advanced phase, the valve timing of
the intake valve is the most advances phase as shown by the solid
line in FIG. 11 so that the engine can be started. The most
advanced phase in this embodiment corresponds to the feasible
phase. On the other hand, the cam shaft 4 positioning the most
delayed phase as shown by the dashed line in FIG. 11, the valve
timing of the intake valve is the most delayed phase so that the
engine can not be started.
[0068] As shown in FIG. 12 and FIG. 13, the trajectory 62 of each
hole 60 is a straight line inclined to the delayed direction Y
according as the trajectory 62 is depart from the center axis O.
The trajectory 72 of each hole 70 is a straight line inclined to
the advanced direction X according to the trajectory 72 is depart
from the center axis O. The trajectory 72, the trajectory 62 and
the trajectory 82 cross one another at the position corresponding
to the rotational phase of the output shaft 16 against the sprocket
11.
[0069] The operation of the second embodiment is described herein
after.
[0070] (First Operation)
[0071] When the rotational phase of the cam shaft 4 relative to the
crankshaft is unchanged during the invariable period, the control
circuit 36 controls the current fed to the stator 34 from the
driving circuit 35 so that the applied torque to the motor shaft 33
is kept constant. Since the relative rotation of the transfer
member 24 to the sprocket 11 does not occur, the relative rotation
of the output shaft 16 to the sprocket 11 does not occur.
Therefore, the rotational phase of the cam shaft 4 against the
crankshaft is kept constant.
[0072] (Second Operation)
[0073] When the rotational phase of the cam shaft 4 relative to the
crankshaft is delayed during the invariable period, the applied
torque to the motor shaft 33 is increased in the advance direction
X as well as the third operation of the first embodiment, and the
transfer member 24 is relatively rotated in the delay direction Y.
The control member 50 is pressed by the side surface 80a of the
trajectory 62 and moves in the trajectory 82 in the advance
direction with making the radial distance long. The control member
50 presses the side surface 60a of the trajectory 62 in the advance
direction and presses the side surface 70b of the trajectory 72 in
the delay direction. The control member 50 moving in the
trajectories 62,72, the output shaft 16 rotates relatively in the
delay direction to the sprocket 11. The cam shaft 4 rotates
relatively in the delay direction to the crank shaft.
[0074] (Third Operation)
[0075] When the rotational phase of the cam shaft 4 relative to the
crankshaft is advanced during the invariable period, the applied
torque to the motor shaft 33 is increased in the delay direction as
well as the first operation of the first embodiment and the
transfer member 50 is rotated relatively in the advance direction X
to the sprocket 24. Thereby the control member 50 is pressed by the
side surface 80b of the trajectory 82, and moves in the delay
direction Y in the trajectory 62 with making the radius distance
short. The control member 50 presses the side surface 60b of the
trajectory 62 in the delay direction Y and presses the side surface
70a in the advance direction X. Thus the output shaft 16 rotates
relatively to the sprocket 11 with moving in the trajectory 62,73.
The output shaft 16 rotates relatively in the advance direction X,
and the rotational phase of the cam shaft against the crankshaft
changes into the advance direction X.
[0076] (Fourth Operation)
[0077] When the electrical shorts or break arise in on of the leads
46r-46t in from the first operation through the third operation,
the load torque is applied to the motor shaft 33 as well as the
fourth operation of the first embodiment and then transmitted to
the transfer member 24 with altering the direction thereof. The
transfer member 24 and the output shaft 16 rotate in the advance
direction X as well as the third operation of this embodiment.
Therefore the rotational phase of the cam shaft 4 is changed to the
advance direction. In this embodiment described above, the
rotational phase of the cam shaft 4 is varied in the safety
direction in which the rotational phase is varied from the most
delayed phase in which the engine can not be started to the most
advanced phase in which the engine can be started.
(Third Embodiment)
[0078] The third embodiment of the present invention is described
hereinafter.
[0079] The VVT controller of the third embodiment controls valve
timing of the intake valve of the engine as well as the first
embodiment.
[0080] As shown in the FIG. 14, the driving circuit 35 has an
auxiliary control circuit 100. The auxiliary circuit 100 has a
microcomputer and an ammeter and is connected with leads 47a-47f
which connect the base of the transistor 44a-44f with the control
circuit 36.
[0081] When the current is not fed from the control circuit 36 to
the transistor 44a-44f due to the electric short or break in the
lead 47a-47f, the auxiliary circuit 100 controls the current fed to
the each coil 42 instead of the control circuit 36. when the
auxiliary circuit 100 detects that no current is fed to at least
one of the lead 47a-47f for a predetermined period with the
ammeter, the auxiliary circuit 100 feeds the current to the
transistor 44a-44f to alter the current value. The driving circuit
35 turns off or turns on the transistor 44a-44f in reverse series
to apply the control torque to the motor shaft 33 in the delay
direction Y. As well as the fourth operation of the first
embodiment, the load torque is transmitted to the motor shaft 33
and the transfer member 24 and the output shaft 16 relatively
rotate in the advance direction or in the delay direction
respectively. The rotational phase of the cam shaft 4 against the
crankshaft changes into the delay direction. The rotational phase
of the cam shaft 4 varies from the most advanced phase to the most
delayed phase. Therefore, the engine can be started even after the
current as a control signal is not fed from the control circuit 36
to the driving circuit 35.
(Fourth Embodiment)
[0082] The fourth embodiment of the present invention is described
hereinafter.
[0083] The VVT controller of the fourth embodiment controls valve
timing of the intake valve of the engine as well as the first
embodiment.
[0084] As shown in FIG. 15, the second converting portion 18 is a
Z-shaped plate which is vertical to the center axis O and has two
holes 70 at the end portion thereof as well as the first
embodiment. At the place of the first converting portion 14 and
transfer member 24 confronting the each hole 70, the holes 60 and
the holes 80 are opened respectively. The holes 60 and the holes 80
has the same shape as the first embodiment. The control member 50
is inserted into the each hole 60, 70, 80 which are confronting one
another. The operation of the phase converting means comprised of
the transfer member 24, the first and second converting portion
14,18 and the control member 50. The phase converting means is
operated as well as the first embodiment.
[0085] The VVT controller of the fourth embodiment has a biasing
member 150. The biasing member is a torsional spring 150 in this
embodiment. A one end 150a of the torsional spring 150 is engaged
with an engage hole 160 which is opened at the first converting
portion 14 of the sprocket 11. The other end 150b of the torsional
spring 150 is engaged with an engage protrusion 170 which is formed
on the transfer member 24. The torsional spring 150 biases the
transfer member 24 in the advance direction X according as the
transfer member 24 rotates in the delay direction Y.
[0086] The operation of the fourth embodiment is described herein
after.
[0087] When the electrical break or short arises in the lead
46r-46t, the load torque is transmitted as well as the first
embodiment. The transfer member 24 and the output shaft 16 rotate
in the advance direction X and the delay direction Y respectively,
and the cam shaft 4 rotates in the delay direction Y which is the
safety direction. At the same time, the side surface 80b presses
the control member 50 by a biasing force applied from the torsion
spring 150 to the transfer member 24. The control member 50 presses
the side surface 60a,70b in the advance direction X and the delay
direction Y respectively. Since the force pressing the side surface
70b in the delay direction Y is applied to the second converting
portion 18 of the output shaft 16 in the delay direction Y as a
biasing torque, the relative rotation of the output shaft 16 is
promoted. Therefore even if the rotational phase of the cam shaft 4
is the most advanced direction in which the engine can not be
started, the rotational phase is changed into the feasible phase
rapidly.
[0088] In the fourth embodiment, a biasing means is comprised of
the biasing member (torsional spring 150), the control member 50
and holes 60,70,80. By engaging the one end 150b of the torsional
spring 150 with the output shaft 16, the biasing torque to the
output shaft 16 is generated by the torsional spring 150.
(Fifth Embodiment)
[0089] The VVT controller of the fifth embodiment adjusts the valve
timing of intake valve by varying the rotational phase of the cam
shaft 4 as shown by an arrow 203 in FIG. 16. The feasible phase of
the cam shaft is different from the feasible phase of the first and
the fourth embodiment.
[0090] FIG. 17, FIG. 18 and FIG. 19 show the situation wherein the
rotational phase of the cam shaft is in the middle phase, in the
most advanced phase, and in the most delayed phase respectively.
The middle phase shown in FIG. 17 is a little advanced phase than
the phase shown in FIG. 19. When the cam shaft 4 is in the middle
phase, the timing of the intake valve is illustrated by the dashed
line in FIG. 16 and the engine can be started. In this embodiment,
the middle phase is the feasible phase. On the other hand, the
rotational phase of the cam shaft 4 is the most advanced phase or
the most delayed phase, the valve timing of the intake valve is
illustrated by the solid line in FIG. 16 and the engine can not be
started.
[0091] The VVT controller of the fifth embodiment has a biasing
member 150 like the fourth embodiment. When the rotational phase of
the output shaft 16 is between the most advanced phase and the most
delayed phase, the end 150b of the biasing member 150 is engaged
with the engage protrusion 200. When the rotational phase of the
output shaft 16 is between the most advance phase and the most
delayed phase, the end 150b of the biasing member 150 is engaged
with the protrusion 170 of the transfer member 24. The biasing
member 150 biases the transfer member 24 in the delay direction Y
by larger force according as the transfer member 24 rotates in the
advance direction X.
[0092] The operation of the fifth embodiment is described herein
after.
[0093] When the rotational phase of the output shaft 16 is between
the most advanced phase and the middle phase, and when the
electrical break or short arise, the load torque is transmitted as
well as the first embodiment. Since the transfer member 24 and the
output member 16 relatively rotate to the sprocket 11 in the
advance direction and the delayed direction respectively, the
rotational phase of the cam shaft 4 is changed into the delay
direction. In this embodiment, the rotational phase of the cam
shaft 4 is varies from the most advanced phase to the middle phase.
After that, the rotational phase of the output shaft 16 reaches the
middle phase, and when the rotational phase of the output shaft 16
is over the middle phase, the transfer member 24 is biased by the
biasing member 150. The side surface 80a of the hole 80 presses the
control member 50 by the force in the delay direction Y, the force
being transmitted from the biasing member 150 to the transfer
member 24. The control member 50 pressed the side surface 60b,70a
into the delay direction and the advance direction respectively.
The force pressing the side surface 70a in the advance direction
biases the second converting portion 18 of the output shaft 16 in
the advance direction X. In this embodiment, the biasing torque is
larger than the torque by which the control member 50 biases the
side surface 70b in the delay direction Y. therefore, the relative
rotation of the output shaft 16 in the middle phase is restricted
from further relative rotation in the delay direction Y.
[0094] When the rotational phase of the output shaft 16 is between
the most advanced phase and the middle phase, and when the
electrical break or short arise in the leads 46r-46t, the biasing
torque is applied to the second converting portion 18. As described
above, since the biasing torque is larger than the torque by which
the control member 50 biases the side surface 70b in the delay
direction Y, the output shaft 16 relatively rotates in the advance
direction X. When the rotational phase of the output shaft 16
reaches the middle phase, the biasing of the transfer member 24 by
the biasing member 150 is ceased. After that, when the output shaft
16 rotates in the delay direction Y by the load torque, this
relative rotation of the output shaft 16 is restricted.
[0095] As described above, the rotational phase of the cam shaft 4
is transferred toward the middle phase in which the engine can be
started.
[0096] In the fifth embodiment, the biasing means is comprised of
the biasing member 150, the control member 150, the holes 60,70,80.
By engaging the one end 150b of the torsional spring 150 with the
output shaft 16, the biasing torque to the output shaft 16 is
generated by the torsional spring 150. When the rotational phase of
the output shaft 16 is in between the most advance phase and the
middle phase, the biasing of the transfer member 24 by the biasing
member 150 is prevented and the biasing torque is no applied to the
output shaft 16. The engage protrusion 200 is of function wherein
the transmission of the biasing force is stopped.
[0097] In the first, the third and the fourth embodiments, each VVT
controllers controls the intake valves in the delay direction. In
the second embodiment, the VVT controller controls the exhaust
valve in the advance direction. In another modification, the VVT
controller controls the valve timing of intake vale in the advance
direction, and controls the valve timing of the exhaust valve in
the delay direction, in which the engine can be started in
safety.
[0098] The feature of the third embodiment can be applied to the
second, fourth, and fifth embodiment. The feature of the fourth and
fifth embodiment can be applied to the second embodiment.
[0099] In the first through the fifth embodiments, the breaking
torque is arisen by the magnets 39 in the motor shaft 33 and is
utilized as the load torque, however, the load torque can be arisen
in a different way without breaking torque.
* * * * *