U.S. patent application number 13/171845 was filed with the patent office on 2012-01-05 for valve control apparatus and electric driving apparatus.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Hideki Hayashi, Toshiaki Uda.
Application Number | 20120001105 13/171845 |
Document ID | / |
Family ID | 45398994 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120001105 |
Kind Code |
A1 |
Hayashi; Hideki ; et
al. |
January 5, 2012 |
VALVE CONTROL APPARATUS AND ELECTRIC DRIVING APPARATUS
Abstract
A valve control apparatus is provided with a valve, a shaft
supporting the valve, an end-gear of an actuator driving the valve.
The shaft is press-inserted into the end-gear. A stopper disposed
on the shaft regulates a valve operation range. The end-gear can
engage with the middle gear of the reduction-gears mechanism even
in out of the gear-operation-angle range. When a rotation angle
sensor detects a rotation angle of the end-gear in out of the
gear-operation-angle range, it is determined that a malfunction
occurs in a rotation-force-transmitting path.
Inventors: |
Hayashi; Hideki;
(Kariya-city, JP) ; Uda; Toshiaki; (Miyoshi-city,
JP) |
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
45398994 |
Appl. No.: |
13/171845 |
Filed: |
June 29, 2011 |
Current U.S.
Class: |
251/78 ;
251/129.01 |
Current CPC
Class: |
F02D 2200/0404 20130101;
Y02T 10/12 20130101; Y02T 10/125 20130101; F16K 31/047 20130101;
Y02T 10/146 20130101; F16K 31/043 20130101; F02B 2275/48 20130101;
F02B 31/06 20130101; F16K 31/046 20130101; F02D 11/107 20130101;
F16K 37/0041 20130101 |
Class at
Publication: |
251/78 ;
251/129.01 |
International
Class: |
F16K 31/44 20060101
F16K031/44; F16K 31/02 20060101 F16K031/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2010 |
JP |
2010-149284 |
Jul 15, 2010 |
JP |
2010-160184 |
Claims
1. A valve control apparatus comprising: a valve opening/closing a
fluid passage; a shaft supporting the valve; a housing
accommodating the valve and the shaft therein; an actuator having a
reduction-gears mechanism which transmits a decelerated rotational
force of a motor to the shaft; a sensor detecting a rotation angle
of the actuator; and a malfunction detecting means for detecting a
malfunction in a rotational-force-transmitting path to the shaft,
wherein the reduction-gears mechanism includes an end-gear engaging
with a gear of the motor to transmit the rotational force of the
motor to the shaft, the end-gear is provided with a connecting
portion and gear teeth engaging with the gear of the motor, the
connecting portion is made of resin material and is provided with a
press-insert hole, the shaft has a press-insert portion which is
press-inserted into the press-insert hole, an exposed portion which
is out of the press-insert hole, and a stopper which radially
extends from the exposed portion, the housing has a stopper surface
with which the stopper is brought into contact, so that a valve
operation range is regulated, the gear teeth is comprised of inside
gear teeth and outside gear teeth, the inside gear teeth engages
with the gear of the motor in a gear-operation-angle range of the
end-gear which corresponds to the valve operation range, the
outside gear teeth engages with the gear of the motor in out of the
gear-operation-angle range, and the malfunction detecting means
determines that a malfunction occurs when the end-gear rotates over
the gear-operation-angle range and the detection value of the
rotation angle sensor is out of normal detection values which
correspond to the valve operation range.
2. A valve control apparatus according to claim 1, wherein the
end-gear has the gear teeth along an entire circumferential
periphery.
3. A valve control apparatus according to claim 1, wherein the
end-gear has the gear teeth partially along a circumferential
periphery.
4. A valve control apparatus according to claim 1, wherein the
sensor includes a magnet fixed to the end-gear and an element
detecting magnetic flux generated by the magnet.
5. A valve control apparatus according to claim 1, wherein the
fluid passage is an intake passage communicating with a combustion
chamber of an internal combustion engine.
6. A valve control apparatus according to claim 1, wherein the
fluid passage is an intake passage communicating with a combustion
chamber of an internal combustion engine, the housing defines the
intake passage and an accommodation chamber which accommodates the
end-gear.
7. A valve control apparatus according to claim 6, further
comprising a seal member which air-tightly seals between the
connecting portion and an inner wall of the accommodation
chamber.
8. A valve control apparatus according to claim 7, wherein a
maximum diameter of the stopper is smaller than an outer diameter
of the seal member.
9. An electric driving apparatus comprising: an electric motor
generating a driving force while receiving an electric current; an
electric current detecting means for detecting the electric current
supplied to the electric motor, and a control means for controlling
an energization to the electric motor so that the driving force is
transmitted to a driven member in order to vary a displacement
magnitude which represents at least one of a variation in position
of the driven member and a variation in posture of the driven
member, wherein the displacement magnitude includes a hold value at
which the driven member is mechanically held and the displacement
magnitude does not vary even though the driving force is continued
to be transmitted from the electric motor to the driven member so
as to vary the displacement magnitude in one direction, the
electric current supplied to the electric motor is stepwise
increased when the displacement magnitude reaches the hold value
after the displacement magnitude has been varied in one direction,
the control means stores a threshold regarding the electric current
supplied to the electric motor for determining whether the
displacement magnitude normally reaches the hold value in a case
that the electric motor is controlled in such a manner that the
displacement magnitude reaches the hold value after the
displacement magnitude has been varied in one direction, and after
the electric motor is energized, the electric current exceeds the
threshold temporarily due to the inrush current, then the electric
current is lowered than the threshold, and when the electric
current excesses the threshold again, the control means determines
that the displacement magnitude has normally reached the hold
value.
10. An electric driving apparatus according to claim 9, wherein
after the electric current is lowered than the threshold, when an
absolute value of a temporal variation rate of the electric current
is lowered than a specified convergence value, the control means
determines that a temporal increase and decrease in electric
current due to the inrush current has been converged.
11. An electric driving apparatus according to claim 9, wherein the
electric motor includes a rotor having a plurality of coils and a
plurality of commutators, a stator having a plurality of magnets,
and two brushes being in contact with the commutators to supply the
electric current to the coils, the electric motor generates a
rotational torque, the control means includes a lock-current
estimating means for estimating a lock-current which is supplied to
the electric motor after the displacement magnitude has reached the
hold value, when the displacement magnitude reaches the hold value,
the rotor stops and each of the brushes is in contact with the
single commutator, the lock-current is denoted by "Ia", when at
least one of brushes is in contact with the multiple commutators,
the lock-current is denoted by "Ib", the control means stores a
lock-current ratio "Ia/Ib", and the threshold is defined in such a
manner as not to exceed an upper value which is obtained by
multiplying the estimated lock-current and the lock-current ratio
"Ia/Ib".
12. An electric driving apparatus according to claim 11, wherein
the lock-current estimating means defines an average value of a
plurality of electric current values detected by the electric
current detecting means as the estimation value of the lock-current
after it is determined that the displacement magnitude normally
reaches the hold value.
13. An electric driving apparatus according to claim 11, further
comprising: a temperature estimating means for estimating an
ambient temperature around the electric motor; a power source
voltage detecting means for detecting a voltage of a power source
which supplies an electricity to the electric motor, wherein the
lock-current estimating means stores a ratio between the
lock-current and the power source voltage as a function of the
ambient temperature around the electric motor, the lock-current
estimating means computes said ratio between the lock-current and
the power source voltage by applying the estimated value of the
ambient temperature to the function, and the lock-current
estimating means computes an estimation value of the lock-current
by multiplying said ratio and the power source voltage.
14. An electric driving apparatus according to claim 13, wherein
after it is determined that the displacement magnitude normally
reaches the hold value, the lock-current estimating means corrects
the function based on a detection value of the electric current
detected by the electric current detecting means, an estimate value
of the ambient temperature around the electric motor estimated by
the temperature estimating means, and a detection value of the
power source voltage detected by the power source voltage detecting
means.
15. An electric driving apparatus according to claim 9, wherein the
control means integrates the electric current supplied to the
electric motor from when the electric motor is energized until when
the electric current is stepwise increased, and the control means
determines whether the displacement value is normal based on the
integrated value.
16. An electric driving apparatus according to claim 9, further
comprising a driving circuit which turns on/off the electric motor
according to a control signal from the control means, wherein the
control means outputs a PWM-signal as the control signal to the
driving circuit to control an energization of the electric motor,
and a sampling frequency at which the control means obtains the
detection values from the current detecting means is greater than a
value which is obtained by dividing the frequency of the PWM-signal
by a duty ratio of the PWM-signal.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Applications
No. 2010-149284 filed on Jun. 30, 2010, and No. 2010-160184 filed
on Jul. 15, 2010, the disclosures of which are incorporated herein
by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a valve control apparatus
including a valve and an actuator. The valve opens/closes a
fluid-passage and the actuator drives the valve. Especially, the
valve control apparatus is used for opening/closing an intake
passage communicating with a combustion chamber of an internal
combustion engine. Further, the present invention relates to an
electric driving apparatus which drives a driven member by use of a
driving force of an electric motor.
BACKGROUND OF THE INVENTION
[0003] Conventionally, a valve control apparatus has a valve which
opens/closes an intake passage communicating with a combustion
chamber of an internal combustion engine, a shaft supporting the
valve, and an actuator driving the valve in order to control an
intake air flow rate. The actuator has an end-gear receiving a
driving force from an electric motor (driving source). The end-gear
is connected to the shaft, so that the valve and the actuator are
connected to each other. Refer to JP-2004-124933A (GB-2393218A) and
JP-2009-013934A (US-2009/0007875A1).
[0004] FIG. 6 shows a valve control apparatus 100 shown in
JP-2004-124933A. An actuator 101 is provided with an end-gear 103
which is made of resin material and receives a driving force from
an electric motor (driving source). A shaft 104 made of metallic
material is press-inserted into a hole 106 of the end-gear 103,
whereby the shaft 104 is connected with the end-gear 103. A
rotation of the end-gear 103 is transmitted to the valve 107
through the shaft 104.
[0005] A housing 109 has a stopper (not shown) to which a
stopper-portion (not shown) of the end-gear 103 confronts so that
an operation range of the valve 107 is regulated. That is, the
stopper regulates an angular operation range of the end-gear 103 so
that the operation range of the valve 107 is restricted. Further,
the valve control apparatus 100 is provided with a sensor (not
shown) which detects a rotational angle of the end-gear 103, so
that a position of the valve 107 is detected.
[0006] In this valve control apparatus 100, since the valve 107 is
connected to the actuator 101 by press-inserting the shaft 104 into
the end-gear 103, its manufacturing cost is relatively low.
[0007] However, in this valve control apparatus 100, if a
press-inserting portion between the shaft 104 and the end-gear 103
is damaged, the sensor detecting the rotational angle of the
end-gear 103 can not detect this malfunction. That is, a
malfunction in a driving-force-transmitting path can not be
detected.
[0008] If the press-inserting portion is broken, it is likely that
the rotation of the end-gear 103 is restricted by the stopper and
only the shaft 104 may spin free. In such a case, even though the
end-gear 103 is restricted by the stopper, the valve 107 rotates
over a restricted range. Since the sensor detects only the
rotational angle of the end-gear 103, it can not be detected that
the valve 107 rotates over the normal range.
[0009] In order to detect the above malfunction, it is conceivable
that another sensor directly detecting a rotational angle of the
shaft 104 is necessary. However, another sensor increases the
manufacturing cost.
[0010] FIG. 7 shows a valve control apparatus 200 shown in
JP-2009-013934A. A sensor 201 directly detects a rotational angle
of a shaft 202 so that an opening degree of the valve 203 is
detected. the shaft 202 rotates over a normal rotational range of
the valve 203 due to a breakage in a connection portion between a
shaft 202 and an end-gear 204, the sensor 201 outputs a detection
value which indicates that the rotational angle of the shaft 202 is
abnormal. Thus, it can be detected that the valve 203 has a
malfunction.
[0011] However, in this valve control apparatus 200, a
configuration of connecting portion between the valve 203 and the
actuator 205 becomes complicated. Further, a gear-holding member
206 for connecting the end-gear 204 to the shaft 202 and a
sensor-holding member 208 for holding a magnet 207 on the shaft 202
are necessary, which increase the number of parts and increase the
manufacturing cost. Thus, even in the valve control apparatus 200,
a malfunction in a connecting portion between the shaft 202 and the
end-gear 204 is not detected with low cost.
[0012] It is well known that an electric driving apparatus drives a
valve, which corresponds to a driven member, by use of a driving
force of an electric motor. The electric driving apparatus is
applied to a valve control apparatus for an internal combustion
engine, which adjusts an intake air quantity or an exhaust gas
quantity.
[0013] The electric driving apparatus is provided with a mechanism
which holds a mechanical position of the driven member. For
example, in a case that the electric driving apparatus is applied
to a tumble-control-valve (TCV) apparatus, a reduction-gears
mechanism is provided with a stopper so that the driven member is
mechanically held at a full-open position or a full-close
position.
[0014] In such an electric driving apparatus, when the driven
member is mechanically held, the electric current supplied to the
electric motor is stepwise increased. For example, when the
TCV-apparatus rotates a tumble-control valve toward the full-close
position, the electric current supplied to the electric motor
varies as shown in FIG. 17. That is, when the electric motor is
energized, the electric current is temporarily rapidly increased
due to an inrush current, and then the electric current is
decreased. When the unheld driven member is mechanically held, the
electric current supplied to the electric motor is stepwise
increased. When the driven member is not mechanically held, the
condition of the driven member is referred to as an unhold
condition, hereinafter. Also, when the driven member is
mechanically held, the condition of the driven member is referred
to as a hold condition, hereinafter.
[0015] It has been needed to correctly determines whether the
condition of the driven member is normally changed from the unhold
condition to the hold condition without respect to the stepwise
increase in the electric current.
[0016] JP-8-19172A and JP-2005-151766A show an electric circuit
configuration in which it is determined that a malfunction occurs
when the electric current supplied to the electric motor exceeds a
specified threshold. However, in this electric circuit, the change
from the unhold condition to the hold condition is not determined
as a normal change.
[0017] JP-2001-4674A shows an electric circuit configuration in
which the supplied electric current is integrated so that an
over-current due to a short circuit is distinguished from a normal
electric current increase due to the condition change from the
unhold condition to the hold condition. However, in this electric
circuit, it is likely determined that no malfunction occurs even if
a malfunction other than over-current occurs.
SUMMARY OF THE INVENTION
[0018] The present invention is made in view of the above matters,
and it is an object of the present invention to provide a valve
control apparatus which enables to detect a malfunction with low
cost.
[0019] Also, the present invention is made in view of the above
matters, and it is another object of the present invention to
provide an electric driving apparatus which is able to determine
whether a driven member is surely moved from the unhold condition
to the hold condition.
[0020] According to the present invention, a valve control
apparatus has a valve opening/closing a fluid passage, a shaft
supporting the valve and an actuator driving the valve. The shaft
is press-inserted into a press-insert hole formed in an end-gear of
the actuator.
[0021] Since the valve is connected to the actuator by
press-inserting the shaft into the end-gear, its manufacturing cost
can be made lower.
[0022] Further, the shaft has an exposed portion which is out of
the press-insert hole. A stopper radially extending from the
exposed portion is provided to the shaft. A housing has a stopper
surface with which the stopper is brought into contact, so that a
valve operation range is regulated. Still further, the valve
control apparatus has a sensor detecting a rotation angle of the
actuator, and a malfunction detecting means for detecting a
malfunction in a rotation-force-transmitting path to the shaft.
[0023] The end-gear has gear teeth comprised of inside gear teeth
and outside gear teeth. The inside gear teeth engages with the gear
of the motor in a gear-operation-angle range of the end-gear which
corresponds to the valve operation range. The outside gear teeth
engage with the gear of the motor in out of the
gear-operation-angle range. The end-gear can engage with a gear of
a motor even in out of the gear-operation-angle range.
[0024] The malfunction detecting means determines that a
malfunction occurs when the end-gear rotates over the
gear-operation-angle range and the detection value of the sensor is
out of the normal detection values corresponding to the valve
operation range.
[0025] According to the above, by detecting the rotation angle of
the actuator, a malfunction in a rotation-force-transmitting path
can be detected. Thus, it is unnecessary to directly detect the
rotation angle of the shaft in order to find a malfunction. The
manufacturing cost is not increased. A damage of a connecting
portion of the shaft and the end-gear can be detected with low
cost.
[0026] According to the present invention, an electric driving
apparatus includes an electric motor generating a driving force
while receiving an electric current; an electric current detecting
means for detecting the electric current supplied to the electric
motor; and a control means for controlling an energization to the
electric motor so that the driving force is transmitted to a driven
member in order to vary a displacement magnitude which represents
at least one of a variation in position of the driven member and a
variation in posture of the driven member.
[0027] The displacement magnitude includes a hold value at which
the driven member is mechanically held and the displacement
magnitude does not vary even though the driving force is continued
to be transmitted from the electric motor to the driven member so
as to vary the displacement magnitude in one direction. The
electric current supplied to the electric motor is stepwise
increased when the displacement magnitude reaches the hold value
after the displacement magnitude has been varied in one
direction.
[0028] The control means stores a threshold regarding the electric
current supplied to the electric motor for determining whether the
displacement magnitude normally reaches the hold value in a case
that the electric motor is controlled in such a manner that the
displacement magnitude reaches the hold value after the
displacement magnitude has been varied in one direction. After the
electric motor is energized, the electric current exceeds the
threshold temporarily due to the inrush current. Then, the electric
current is lowered than the threshold. After that, when the
electric current excesses the threshold again, it is determined
that the displacement magnitude normally reach the hold value.
[0029] Thereby, it can be able to determine whether the driven
member is normally moved from the unhold condition to the hold
condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Other objects, features and advantages of the present
invention will become more apparent from the following description
made with reference to the accompanying drawings, in which like
parts are designated by like reference numbers and in which:
[0031] FIG. 1 is a fragmentally sectional view showing a
tumble-control-valve control apparatus according to a first
embodiment;
[0032] FIG. 2 is an enlarged cross sectional view showing an
essential portion of the tumble-control-valve control apparatus
according to the first embodiment;
[0033] FIG. 3A is a cross sectional view showing a stopper;
[0034] FIG. 3B is a plain view of an end-gear according to the
first embodiment;
[0035] FIG. 4A is a cross sectional view showing a stopper;
[0036] FIG. 4B is a plain view of an end-gear according to a second
embodiment;
[0037] FIG. 5 is a cross sectional view showing a stopper according
to a third embodiment;
[0038] FIG. 6 is a cross sectional view showing a conventional
valve control apparatus; and
[0039] FIG. 7 is a cross sectional view showing a conventional
valve control apparatus.
[0040] FIG. 8A is a cross sectional view showing an essential part
of a TCV apparatus according to a fourth embodiment;
[0041] FIG. 8B is a cross sectional view showing a stopper
configuration of the TCV apparatus according to the fourth
embodiment;
[0042] FIG. 9A is a chart showing a circuit configuration of an
electric driving apparatus;
[0043] FIG. 9B is a graph showing an electric current supplied to
the electric motor;
[0044] FIG. 10A is a chart for explaining a lock-current in a case
that both brushes are in contact with a single commutator;
[0045] FIG. 10B is a chart for explaining a lock-current in a case
a single brush is in contact with two brushed;
[0046] FIG. 11 is a main flowchart for operating an electric
driving apparatus according to the fourth embodiment;
[0047] FIG. 12 is a sub-flowchart for operating an electric driving
apparatus according to the fourth embodiment;
[0048] FIG. 13 is another sub-flowchart for operating an electric
driving apparatus according to the fourth embodiment;
[0049] FIG. 14 is a chart showing a circuit configuration of an
electric driving apparatus according to a fifth embodiment;
[0050] FIG. 15A is a chart showing a table data according to the
fifth embodiment;
[0051] FIG. 15B is a chart for explaining an update of the table
data according to the fifth embodiment;
[0052] FIG. 16A is a graph showing an electric current supplied to
the electric motor according to a sixth embodiment;
[0053] FIG. 16B is a graph showing a relationship between a
frequency of PWM-signal and a sampling frequency; and
[0054] FIG. 17 is a graph showing an electric current for
explaining a conventional driving apparatus.
DETAILED DESCRIPTION OF EMBODIMENTS
First Embodiment
[0055] [Structure of first embodiment]
[0056] Referring to FIGS. 1 to 3, a first embodiment of the present
invention will be described. In this embodiment, the present
invention is applied to a tumble-control-valve control apparatus,
which is referred to as a TCV control apparatus, hereinafter. The
TCV control apparatus adjusts flow passage areas of intake passages
2 each of which communicates with a combustion chamber of each
cylinder of an internal combustion engine, whereby tumble flow is
generated in each combustion chamber.
[0057] The TCV control apparatus is provided with an intake
manifold (housing) 3 defining an intake passages 2 therein, a valve
4 opening/closing the intake passage 2, a shaft 5 supporting the
valve 4, an electronic actuator 6 driving the valve 4 through the
shaft 5, a rotation angle sensor 7 detecting an opening degree of
the valve 4, and an electronic control unit (ECU: not shown)
receiving detection signals from the rotation angle sensor 7.
[0058] The intake manifold 3 is a casing which forms a plurality of
intake passages 2 and is made of polyamide resin. Each of intake
passages 2 has rectangular cross section and communicates with each
intake port (not shown) of a cylinder head.
[0059] A tumble control valve, which is referred to as TCV
hereinafter, is provided in the intake manifold 3 in order to
generate tumble flow in the combustion chamber.
[0060] The TCV is comprised of a valve housing 11 accommodated in a
housing storage chamber 10 of the intake manifold 3 and the valve 4
which is rotatably accommodated in the valve housing 11. The number
of the housing storage chamber 10 is equal to the number of the
cylinders. Each of the valve housings 11 is held in each housing
storage chamber 10.
[0061] The intake manifold 3 and the valve housing 11 respectively
have penetrating holes 13, 14 through which the shaft 5 is
rotatably inserted.
[0062] The shaft 5 supports the valve 4 and its end portion is
connected to the actuator 6. The shaft 5 is made of metallic
material and has polygonal cross section.
[0063] Further, the intake manifold 3 has an accommodation chamber
17 which accommodates a part of the actuator 6. The intake passage
2 communicates with the accommodation chamber 17 through the
penetrating holes 13, 14.
[0064] The valve 4 is made of polyamide resin. A rotation axis of
the valve 4 extends in a direction perpendicular to an air flow
direction in the intake passage 2. The valve 4 has a polygonal hole
19 through which the shaft 5 is inserted. The valve 4 and the shaft
5 rotate together. The cross section of the polygonal hole 19 is
substantially the same as the cross section of the shaft 5, whereby
a relative rotation between the shaft 5 and the valve 4 is
prevented.
[0065] The valve 4 is rotated in the valve housing 11 to vary the
flow passage area of the intake passage 2. When the flow passage
area of the intake passage is reduced, the tumble flow is generated
in the combustion chamber. Such a tumble flow improves a combustion
efficiency and fuel economy, and reduces emissions.
[0066] As shown in FIG. 1, the valve 4 has a notch portion 20. When
the valve 4 fully closes the intake passage 2, a rectangular
aperture is defined between the valve 4 and the valve housing 11 by
the notch portion 20. The intake air flows through this rectangular
aperture, so that the tumble flow is generated in the combustion
chamber.
[0067] When the valve 4 is fully opened in its operational range,
the flow passage area of the intake passage 2 becomes maximum.
[0068] When the valve 4 is fully closed in its operational range,
the flow passage area of the intake passage 2 becomes minimum.
[0069] It should be noted that the valve operational range
represents a rotational angle range within which the valve 4 can be
rotated.
[0070] The rotational angle range of the valve 4 is defined by
stoppers (not shown). When the valve 4 is fully closed, one of
stoppers is in contact with the valve 4. When the valve 4 is fully
opened, the other stopper is in contact with the valve 4.
[0071] The actuator 6 is provided with an electric motor (not
shown), a reduction-gears mechanism and an actuator case 21 which
accommodates the reduction-gears mechanism.
[0072] The reduction-gears mechanism includes a motor gear
connected to an output shaft of the electric motor, a middle gear
engaging with the motor gear, and an end-gear 25 engaging with the
middle gear.
[0073] The end-gear 25 made of polyamide resin has an engaging
portion 27 and a gear portion 28. The engaging portion 27 defines a
press-insert hole 26 therein. The gear portion 28 is engaged with
the middle gear (not shown). The engaging portion 27 extends from
the gear portion 28, and has a middle-diameter portion 31 and a
small-diameter portion 32. The diameter of the middle-diameter
portion 31 is smaller than that of the gear portion 28, and the
diameter of the small-diameter portion 32 is smaller than that of
the middle-diameter portion 31.
[0074] The press-insert hole 26 extends along a center axis of the
small-diameter portion 32 and the middle-diameter portion 31. An
end portion 33 of the shaft 5 is press-inserted into the
press-insert hole 26, whereby the shaft is concentrically connected
to the end-gear 25. The shaft 5 and the end-gear 25 rotate
together. This end portion 33 of the shaft 5 is referred to as a
press-insert portion 33. The cross section of the press-insert hole
26 is substantially the same as the cross section of the shaft 5,
whereby a relative rotation between the shaft 5 and the end-gear 25
is prevented.
[0075] The other portion of the shaft 5, which is not
press-inserted into the hole 26, is referred to as an exposed
portion 34. The exposed portion 34 is provided with a stopper 35
which radially extends. As shown in FIG. 3A, the stopper 35 is
comprised of a disc portion 37 and a stopper-contacting portion 38
which radially outward protrudes from the disc portion 37.
[0076] The accommodation chamber 17 is comprised of a large chamber
40, a middle chamber 41, and a small chamber 42. The penetrating
hole 13 communicates with the small chamber 42.
[0077] The middle-diameter portion 31 of the end-gear 25 is
accommodated in the large chamber 40, and the small-diameter
portion 32 is accommodated in such a manner as to extend from the
large chamber 40 to the small chamber 42. The gear portion 28 is
accommodated in the actuator case 21. The exposed portion 34 and
the stopper 35 are accommodated in the small chamber 42.
[0078] As shown in FIG. 3A, the intake manifold 3 has two stopper
walls 44, 45. The stopper-contacting portion 38 comes into contact
with one of the stopper walls 44, 45, whereby the rotation of the
shaft 5 is regulated and the operation range of the valve 4 is also
regulated.
[0079] The stopper wall 44 corresponds to a full-close position of
the valve 4 and the other stopper wall 45 corresponds to a
full-open position of the valve 4. The small chamber 42 is
comprised of a first small chamber 46 and a second small chamber
47. The disc portion 37 is accommodated in the first small chamber
46, and the stopper-contacting portion 38 is accommodated in the
second small chamber 47. The stepped surfaces between the first
small chamber 46 and the second small chamber 47 respectively
correspond to the full-close stopper wall 44 and the full-open
stopper wall 45.
[0080] When the stopper-contacting portion 38 is brought into a
contact with the full-close stopper wall 44, the valve 4 is
positioned at a full-close position. When the stopper-contacting
portion 38 is brought into a contact with the full-open stopper
wall 45, the valve 4 is positioned at a full-open position. The
valve operation range is from the full-close position to the
full-open position.
[0081] Further, since the end-gear 25 rotates along with the shaft
5 and the valve 4, an operation range of the end-gear 25 is also
restricted as shown in FIG. 3B. That is, the operation range of the
end-gear 25 is identical to the valve operation range. When the
valve 4 is at the full-close position, the end-gear 25 is
positioned at a full-close gear position. When the valve 4 is at
the full-open position, the end-gear 25 is positioned at a
full-close gear position.
[0082] The gear portion 28 has gear teeth which are able to engage
with the middle gear of the reduction-gears mechanism even if the
end-gear 25 rotates over the operation range. That is, the gear
portion 28 has gear teeth which are comprised of inside gear teeth
49 engaging with the middle gear in the gear-operation-angle range
and outside gear teeth 50 engaging with the middle gear in out of
the gear-operation-angle range, as shown in FIG. 3B.
[0083] In the present embodiment, the gear portion 28 has the gear
teeth 49, 50 along its entire circumferential periphery. The
end-gear 25 can engage with the middle gear of the reduction-gears
mechanism even in out of the gear-operation-angle range.
[0084] A concave portion 51 is formed on an end surface of the gear
portion 28. The actuator case 21 has a protrusion 52 which is
inserted into the concave portion 51, whereby the end-gear 25 is
connected to the actuator case 21, as shown in FIG. 2.
[0085] The TCV control apparatus is provided with a seal member 53
(for example, an oil seal or an X-ring) between the engaging
portion 27 and the accommodation chamber 17. An outer surface of
the seal member 53 is in contact with an inner surface of the
middle chamber 41, and an inner surface of the seal member 53 is in
contact with an outer surface of the small-diameter portion 32.
Thereby, the seal member 53 prevents an air-leakage from the intake
passage 2 toward the actuator case 21. The maximum diameter of the
stopper 35 is greater than that of the seal member 53.
[0086] The rotation angle sensor 7 includes a magnet 54 fixed in
the end-gear 25 and a Hall element 55 detecting magnetic flux
generated by the magnet 54. Specifically, the magnet 54 is fixed in
the end-gear 25 by insert-molding, and the Hall element 55 is
disposed on the actuator case 21.
[0087] The magnet 54 and the Hall element 55 are arranged in such a
manner as to perform a relative movement to each other. When the
end-gear 25 rotates, a relative position between the magnet 54 and
the Hall element 55 is varied. The magnetic flux density passing
through the Hall element 55 is also varied. Based on this variation
in magnetic flux density, the rotation angle sensor 7 detects the
rotation angle of the end-gear 25. Instead of the Hall element 55,
a Hall IC or a magnetic resistance element can be used.
[0088] In the present embodiment, since the rotation angle of the
shaft 5 holding the valve 4 is identical to the rotation angle of
the end-gear 25, the opening degree of the valve 4 can be detected
by obtaining the rotation angle of the end-gear 25.
[0089] The ECU has a microcomputer including a central processing
unit (CPU), a read only memory (ROM), a random access memory (RAM),
an input circuit, an output circuit and a timer.
[0090] The ECU functions as a valve position computing means for
computing an opening degree of the valve 4 based on the detection
value of the rotation angle sensor 7.
[0091] Also, the ECU functions as a malfunction detecting means for
detecting a malfunction in a driving force transmitting path to the
shaft 5.
[0092] The ECU stores the detection values detected by the rotation
angle sensor 7, which correspond to the valve operation range, as
normal detection values. That is, the ECU stores the detection
value detected by the rotation angle sensor 7 in a case that the
end-gear 25 rotates in the gear-operation-angle range.
[0093] The malfunction detecting means determines that a
malfunction occurs when the end-gear 25 rotates over the
gear-operation-angle range and the detection value of the rotation
angle sensor 7 is out of the normal detection values. A specific
way of detecting a malfunction will be described hereinafter.
[Operation of First Embodiment]
[0094] (i) Normal condition
[0095] In a case that the end-gear 25 and the shaft 5 are normally
connected to each other, the end-gear 25 rotates from the full-open
gear position to the full-close gear position. Also, the valve 4
rotates from full-open position to the full-close position. When
the stopper-contacting portion 38 is brought into contact with the
full-close stopper wall 44, the valve 4 stops rotating at the
full-close position. The end-gear 25 also stops at the full-close
gear position.
[0096] The rotation angle sensor 7 outputs detection signals which
indicate the rotation angle of the end-gear 25 is within the
gear-operation-angle range. Thus, the malfunction detecting means
determines that no malfunction occurs.
(ii) Abnormal condition
[0097] If the connecting portion between the end-gear 25 and the
shaft 5 is broken, the end-gear 25 rotates over the full-close gear
position. The end-gear 25 rotates free without respect to the
full-close stopper wall 44. That is, the end-gear 25 rotates out of
the gear-operation-angle range. At this moment, the rotation angle
sensor 7 outputs detection signals which indicate the rotation
angle of the end-gear 25 is out of the gear-operation-angle range.
Thus, the malfunction detecting means determines that a malfunction
occurs in a driving power transmitting path from the end-gear 25 to
the shaft 5. Then, a warning lump is turned on to notify a
passenger of the malfunction.
[0098] Besides, in a case that the detection value of the rotation
angle sensor 7 is proportional to the opening degree of the valve,
a lower limit value and an upper limit value of the detection
value, which respectively correspond to the full-close position and
the full-open position, are stored in a memory as a normal
detection value of the rotation angle sensor 7 corresponding to the
valve operation range. When the actual detection value becomes
lower than the lower limit value, or when the actual detection
value becomes higher than the upper limit value, it is determined
that a malfunction occurs.
[Advantages of First Embodiment]
[0099] In the first embodiment, since the valve 4 is connected to
the actuator 6 by press-inserting the shaft 5 into the end-gear 25,
its manufacturing cost can be made lower.
[0100] The end-gear 25 can engage with the middle gear of the
reduction-gears mechanism even in out of the gear-operation-angle
range. The malfunction detecting means determines that a
malfunction occurs when the end-gear 25 rotates over the
gear-operation-angle range and the detection value of the rotation
angle sensor 7 is out of the normal detection values corresponding
to the valve operation range.
[0101] When the driving force is not transmitted from the end-gear
25 to the shaft 5 due to a malfunction, this malfunction can be
detected by detecting the rotation angle of the end-gear 25. Thus,
it is unnecessary to directly detect the rotation angle of the
shaft 5 in order to find a malfunction. The manufacturing cost is
not increased. A damage of a connecting portion of the shaft 5 and
the end-gear 25 can be detected with low cost.
[0102] Further, according to the present embodiment, the maximum
diameter of the stopper 35 is smaller than the diameter of the seal
member 53. That is, the diameter of the stopper 35 is smaller than
the inner diameter of the middle chamber 41. Thus, the end-gear 25,
the shaft 5, and the seal member 53 are easily assembled in the
accommodation chamber 17. Specifically, after the stopper 35 is
arranged in the small chamber 42 through the middle chamber 41, the
seal member 53 is assembled in the middle chamber 41. It is less
likely that the stopper 35 conflicts with the seal member 53.
Second Embodiment
[0103] Referring to FIGS. 4A and 4B, a second embodiment will be
described. In the second and the successive embodiments, the same
parts and components as those in the first embodiment are indicated
with the same reference numerals and the same descriptions will not
be reiterated.
[0104] The second embodiment is different from the first embodiment
in the configuration of the stopper. That is, stop-screws 58 are
provided on step-surfaces 57 between the first small chamber 46 and
the second small chamber 47. A tip end of the stop-screw 58
functions as a full-close position stopper 44, and a tip end of the
other stop-screw 58 functions as a full-open position stopper
45.
[0105] In the second embodiment, the gear portion 28 has gear teeth
partially along its circumferential periphery, as shown in FIG. 4B.
That is, the inside gear teeth 49 are provided in the
gear-operation-angle range, and the outside gear teeth 50 are
provided at both sides of the inside gear teeth 49. The second
embodiment has the same advantages as the first embodiment.
Third Embodiment
[0106] Referring to FIG. 5, a third embodiment will be described.
The third embodiment is different from the first embodiment in the
configuration of the stopper and the stopper portion 35. The
stopper portion 35 is comprised of a disc portion 37 and a concave
portion 59. At circumferential both ends of the concave portion 59,
step portions 60 are formed.
[0107] The inner diameter of the small chamber 42 is slightly
larger than the outer diameter of the disc portion 37. A projection
61 is formed on an inner wall surface of the small chamber 42 in
such a manner as to project toward the concave portion 59. One side
surface of the projection 61 functions as the full-open position
stopper 45, and the other side surface of the projection 61
functions as the full-close position stopper 44. These step
portions 60 and stoppers 44, 45 regulate the operation angle range
of the shaft 5. The third embodiment has the same advantages as the
first embodiment.
[Modification]
[0108] The rotation angle sensor 7 can be arranged in such a manner
as to detect the rotation angle of the actuator 6. That is, the
rotation angle sensor 7 may detect the rotation angle of the output
shaft of the electric motor, the motor gear, or the middle
gear.
[0109] The detection value of the rotation angle sensor 7 may be
ON-OFF signal. A switching position between ON-signal and OFF
signal is previously stored. If the detection value is switched at
improper switching position, it is determined that a malfunction
occurs.
[0110] The present invention can be applied to a
swirl-control-valve control apparatus, a throttle-valve control
apparatus, or an EGR-valve control apparatus.
Fourth Embodiment
[0111] Referring to FIGS. 8A to 10B, a configuration of an electric
driving apparatus will be described.
[0112] The electric drive apparatus 301 includes an electric motor
302. The electric drive apparatus 301 is applied to a
tumble-control-valve (TCV) apparatus 304 which drives a tumble
control valve 304.
[0113] That is, the TCV apparatus 304 is provided with the tumble
control valve 303 and the electric motor 302. The tumble control
valve 303 is rotatably supported in an intake manifold 306 to
adjust the flow passage area of an intake passage 307.
[0114] The valve 303 is fixed on a valve shaft 308. The valve 303
has rectangular shape. The valve 303 has a notch portion 309.
[0115] The drive apparatus 301 is provided with the electric motor
302 and an electric current detecting means 311 which detects the
electric current supplied to the electric motor 302. Further, the
drive apparatus 301 is provided with a control means 312 which
controls the energization of the electric motor 302 and a driving
circuit 314 which turns on/off the electric motor 302 according to
a control signal from the control means 312.
[0116] The electric motors 302 is a well-known DC motor which is
comprised of a rotor 318 having a plurality of coils 316 and a
plurality of commutator 317, a stator 320 having a plurality of
magnets 319, and two brushes 321a, 321b.
[0117] The electric current detecting means 311 is a well-known
electric current detecting circuit which detects electric current
supplied to the electric motor 302 based on voltage drop in a shunt
resistance 324.
[0118] The control means 312 is a microcomputer having a CPU, a
ROM, a RAM, an input device and an output device.
[0119] The driving circuit 314 has four switching elements 325 to
rotate the electric motor 302 in the normal direction or the
reverse direction.
[0120] The rotation torque generated by the electric motor 302 is
transmitted to the valve shaft 308 thorough a reduction-gears
mechanism. The valve shaft 308 is concentrically connected to an
end-gear 326 of the reduction-gears mechanism. An end portion 326a
of the end-gear 326 is supported by the intake manifold 306 through
an oil-seal 327.
[0121] A stopper 329 is provided to the valve shaft 308.
[0122] The stopper 329 is comprised of a disc portion 330 and a
stopper-contacting portion 331 which radially outward protrudes
from the disc portion 330. The stopper 329 is rotatably
accommodated in a chamber 332.
[0123] The chamber 332 is comprised of a first chamber 333 and a
second chamber 334. The disc portion 330 is accommodated in the
first chamber 333 and the stopper-contacting portion 331 is
accommodated in the second chamber 334. Both end walls of the
second chamber 334 define stopper walls 335, 336.
[0124] When the stopper-contacting portion 331 is in contact with
the stopper wall 335 or the other stopper wall 336, the valve 303
is mechanically held. When the valve 303 is full-closed, the
stopper-contacting potion 331 is in contact with the full-close
stopper wall 335. When the valve 303 is full-opened, the
stopper-contacting portion 331 is in contact with the full-open
stopper wall 336.
[0125] Thus, even if the valve 303 receives the rotation torque
from the electric motor 302, the valve 303 does not rotate over the
full-close stopper wall 335 or the full-open stopper wall 336.
[0126] When the stopper-contacting portion 331 is brought into
contact with one of the stopper walls 335, 336 (hold condition),
the electric current supplied to the electric motor 302 is stepwise
increased.
[0127] When the valve 303 rotates to the full-open position or the
full-close position, the electric current supplied to the electric
motor 302 varies as shown in FIG. 9B. That is, when the electric
motor 302 is energized, the electric current is temporarily rapidly
increased due to an inrush current, and then the electric current
is decreased. When the valve 303 is mechanically held, the electric
current supplied to the electric motor 302 is stepwise increased.
The unhold condition is comprised of an initial condition and a
rotation condition. In the initial condition, the electric current
supplied to the electric motor 302 is steeply varied due to the
inrush current. In the rotation condition, the electric current
supplied to the motor 302 is constant and the valve 303 rotates in
a constant speed. It should be noted that the electric current of
the time when the valve 303 is mechanically held is referred to as
a lock-current.
[0128] The control means 312 stores a threshold "Ithr" with respect
to the electric current supplied to the motor 302. When the
electric current is temporarily increased and decreased due to the
inrush current, and then exceeds the threshold "Ithr", the control
means 312 determines that the valve 303 is normally brought into
the hold condition.
[0129] That is, after the electric motor 302 is energized, the
electric current exceeds the threshold "Ithr" temporarily due to
the inrush current. Then, the electric current is lowered than the
threshold "Ithr". After that, when the electric current excesses
the threshold "Ithr" again, it is determined that the valve 303 is
normally full-closed or full-opened.
[0130] With respect to the temporal increase and decrease in
electric current due to the inrush current, after the electric
current is lowered than the threshold "Ithr", when the absolute
value of the temporal variation rate of the electric current is
lowered than a specified convergence value, the control means 312
determines that a temporal increase and decrease in electric
current due to the inrush current has been converged.
[0131] Further, the control means 312 functions as a lock-current
estimating means which estimates the lock-current. When the valve
303 is in the hold condition, the rotor 318 stops, and each of the
brushes 321a, 321b is in contact with a single commutator 317, the
lock-current is denoted by "Ia". When at least one of brushes 321a,
321b is in contact with two commutators 317, the lock-current is
denoted by "Ib". The control means 312 stores a lock-current ratio
"Ia/Ib". The estimated lock-current is denoted by "Iss". The
threshold "Ithr" is defined in such a manner as not to exceed an
upper value which is obtained by multiplying "Iss" by "Ia/Ib".
[0132] For example, as shown in FIGS. 10A and 10B, the electric
motor 302 has three-phase coils 316a-316c in delta connection. Each
of commutators 317A-317C is connected to the coils 316a-316c. The
resistance value of the coils 316a-316c is denoted by "r".
[0133] FIG. 10A shows a case in which each of brushes 321a, 321b is
in contact with only the corresponding commutator 317B, 317C. The
lock-current is denoted by "Ia". FIG. 10B shows a case in which the
brush 321a is in contact with the commutators 317A, 317B and the
brush 321b is in contact with only the commutator 317C. The
lock-current is denoted by "Ib".
[0134] In a case shown in FIG, 10A, the combined resistance between
the brushes 321a, 321b is expressed by "r.times.(2/3)". In a case
shown in FIG. 10B, the combined resistance between the brushes
321a, 321b is expressed by "r.times.(1/2)". Thus, the ratio "Ia/Ib"
is 0.75 and the threshold "Ithr" is defined so as to be smaller
than an upper value (=Iss.times.0.75).
[0135] In a case that the electric motor 302 has (2N+1)-phase coils
316, the ratio "Ia/Ib" can be expressed by (2N+1)/(2 (N+1)). In a
case that the electric motor 302 has 2N-phase coils 316, the ratio
"Ia/Ib" can be expressed by (2N-1)/(2 (N-1)).
[0136] After it is determined that the valve 303 is normally
brought into the hold condition, the lock-current estimating means
defines an average of a plurality of detection current detected by
the electric current detecting means 311 as an estimation value
"Iss" of the lock-current.
[0137] When the valve 303 is rotated to the hold condition next
time, the control means 312 defines the threshold "Ithr" smaller
than the upper value (=Iss.times.(Ia/Ib)), and determines whether
the valve 303 is normally full-closed or full-opened.
[0138] Further, the control means 312 integrates the electric
current from when the electric motor 302 is energized until when
the electric current is stepwise increased. Based on the integrated
value, the control means 312 determines whether the rotational
position of the valve 303 is normal. That is, in a case that the
electric motor 302 is a DC motor, a rotation speed N(t) [rad/s] of
the motor 302 and the electric current I(t) has a linear relation
as expressed by following formula (1).
N(t)=a-bI(t) (1)
[0139] In a case that a time period and a rotation angle of the
motor 302 from when the electric motor 302 is energized until when
the electric current is stepwise increased are respectively
expressed by T1 [s] and .theta. [rad], the rotation angle .theta.
can be computed by definite-integrating the rotation speed N(t)
from 0 to T1 with respect to time "t". Thus, the rotation angle
.theta. can be expressed by following formula (2).
.theta.=aT1+b.intg..sub.0.sup.T1I(t)dt (2)
[0140] As above, since the rotational position of the valve 303
corresponds to the rotational angle of the electric motor 302, it
can be determined whether the rotational position of the valve 303
is normal based on the above integrated value.
[Control Processing of Fourth Embodiment]
[0141] Referring to FIGS. 11 to 13, a control processing of the
driving apparatus 301 will be described hereinafter.
[0142] FIG. 11 is a main flowchart of a processing in which it is
determined whether the rotational position of the valve 303
normally reaches the full-close position in a case that the valve
303 rotates from the full-open position toward the full-close
position. This flowchart starts when the electric motor 302 is
energized.
[0143] In step S1, the computer determines whether the valve 303
has moved from the initial condition to the rotation condition.
When the answer is NO, the procedure proceeds to step S2. When the
answer is YES, the procedure proceeds to step S3.
[0144] The determination of whether the valve 303 has moved from
the initial condition to the rotation condition is conducted by
executing a sub-flowchart shown in FIG. 12.
[0145] In step S101, the computer determines whether an absolute
value "ABVR" of a temporal variation ratio of the electric current
is lower than or equal to a specified convergent value "COV". An
absolute value of a difference value between the currently detected
electric current and the previously detected electric current is
defined as the absolute value of the temporal variation ratio of
the electric current.
[0146] When the answer is YES in step S101, the procedure proceeds
to step S102. When the answer is NO in step S101, the procedure
proceeds to step S103. In step S103, the computer determines that
the valve 303 has not moved to the rotation condition. The
procedure goes back to step S1 of the main flowchart. The answer in
step S1 is NO.
[0147] In step S102, the computer determines whether the electric
current is less than the threshold "Ithr". When the answer is YES
in step S102, the procedure proceeds to step S104. When the answer
is NO in step S102, the procedure proceeds to step S103. In step
S103, the computer determines that the valve 303 has not moved to
the rotation condition. The procedure goes back to step S1 of the
main flowchart. The answer in step S1 is NO.
[0148] In step S104, the computer determines that the valve 303 has
moved to the rotation condition. The procedure goes back to step S1
of the main flowchart. The answer in step S1 is YES.
[0149] In step S2, the computer determines whether an elapsed time
"Telp1" from energization of the motor 302 exceeds an upper limit
time of the initial condition. When the answer is NO in step S2,
the procedure goes back to step S1. When the answer is YES in step
S2, the procedure proceeds to step S4 in which the computer
determines that the valve 303 is stuck. The upper limit time of the
initial condition is defined based on a time period which is
required to converge the temporal increase/closed in electric
current due to the inrush current.
[0150] In step S3, the computer determines whether the valve 303
has moved from the rotation condition to the hold condition. When
the answer is NO, the procedure proceeds to step S5. When the
answer is YES, the procedure proceeds to step S6.
[0151] The determination of whether the valve 303 has moved from
the rotation condition to the hold condition is conducted by
executing a sub-flowchart shown in FIG. 13.
[0152] In step S301, the computer determines whether the electric
current is greater than the threshold "Ithr". When the answer is
YES in step S301, the procedure proceeds to step S302. When the
answer is NO in step 5301, the procedure proceeds to step S303.
[0153] In step S302, the computer determines that the valve 303 has
moved to the hold condition. The procedure goes back to step S3 of
the main flowchart. The answer in step S3 is YES. In step S303, the
computer determines that the valve 303 has not moved to the hold
condition. The procedure goes back to step S3 of the main
flowchart. The answer in step S3 is NO.
[0154] In step S5, the computer determines whether an elapsed time
"Telp2" after the valve 303 has moved to the rotation condition
exceeds a specified upper limit time. When the answer is NO, the
procedure goes back to step S3. When the answer is YES, the
procedure proceeds to step S7.
[0155] In step S6, the computer determines whether an elapsed time
"Telp3" after the valve 303 has moved to the rotation condition
exceeds a specified lower limit time. When the answer is NO in step
S6, the procedure proceeds to step S8 in which the computer
determines that a malfunction exists in the rotation position of
the valve 303.
[0156] The upper limit time and the lower limit time of the
rotation condition are defined based on a time period which is
necessary for the valve 303 to rotate from the full-open position
to the full-close position. It should be noted that when the
rotation quantity of the valve 303 from the full-open position is
excessively small, it is determined that a malfunction exists in
the rotation position of the valve 303.
[0157] In step S7, the computer determines whether the electric
current is smaller than a break-wire value. The break-wire value is
a reference value for determining whether a breaking of wire occurs
in the electric motor 302. When the answer is YES in step S7, the
procedure proceeds to step S9 in which the computer determines that
a breaking of wire occurs. When the answer is NO in step S7, the
procedure proceeds to step S10 in which the computer determines
that a disengage malfunction occurs.
[0158] The disengage malfunction represents that a disengagement
occurs in a torque transmitting path between the electric motor 302
and the valve shaft 308. For example, when a connecting portion
between the valve shaft 308 and the end-gear 326 is broken, the
end-gear 326 is disengaged from the valve shaft 308. Such a
breakage is referred to as a disengage malfunction.
[0159] When the answer is NO in step S6, the procedure proceeds to
step S11 in which the valve 303 is normally rotated form the
full-open position to the full-close position. Then, the procedure
proceeds to step S12 in which the lock-current is estimated to end
the main flowchart.
[0160] The control means 312 functions as a lock-current estimating
means by executing step S12.
[Advantages of Fourth Embodiment]
[0161] In a case that the valve 303 rotates from the full-open
position to the full-close position, the control means 312 stores
the threshold "Ithr" for determining whether the valve 303 is
normally full-closed. After the electric motor 302 is energized,
the electric current exceeds the threshold "Ithr" temporarily due
to the inrush current. Then, the electric current is lowered than
the threshold "Ithr". After that, when the electric current
excesses the threshold "Ithr" again, it is determined that the
valve 303 is normally full-closed.
[0162] Thereby, based on the appropriately established threshold
"Ithr", it is able to correctly determine whether the valve 303 is
surely moved from the rotation condition to the hold condition.
[0163] If the valve 303 has not moved from the rotation condition
to the hold condition, the computer determines that the valve 303
is stuck in step S4, a malfunction exists in the rotation position
of the valve 303 in step S8, a breaking of wire occurs in step S9,
or the disengage malfunction occurs in step S10.
[0164] Also, after the electric current is lowered than the
threshold "Ithr", when the absolute value of the temporal variation
rate of the electric current is lowered than the specified
convergence value, the control means 312 determines that the inrush
current has been converged and the valve 303 has moved from the
initial condition to the rotation condition. Thereby, even though
the time period required to converge the inrush current fluctuates,
the convergence of the inrush current can be surely detected.
[0165] The control means 312 stores the ratio "Ia/Ib" and the
threshold "Ithr" is defined in such a manner as not to exceed an
upper value which is obtained by multiplying "Iss" by "Ia/Ib".
Thereby, without respect to a contact condition between the brushes
321a, 321b and the commutators 317A-317C, it is surely determined
whether the valve 303 has normally moved from the unhold condition
to the hold condition.
[0166] Further, the control means 312 integrates the electric
current from when the electric motor 302 is energized until when
the electric current is stepwise increased. Based on the integrated
value, the control means 312 determines whether the rotational
position of the valve 303 is normal. Since the electric current
supplied to the electric motor 302 and the rotation speed of the
motor 302 has a liner correlation, the above integrated value and
the rotation angle of the motor 302 has also liner correlation. The
rotation angle of the motor 302 corresponds to the rotational
position of the valve 303 one-on-one. Therefore, it can be
determined whether the rotational position of the valve 303 is
normal based on the integrated value with high accuracy.
Fifth Embodiment
[0167] As shown in FIG. 14, the driving apparatus 301 is provided
with a temperature estimating means 340 which estimates ambient
temperature around the electric motor 302, and a voltage detecting
means 341 which detects voltage of electric power source 313. The
electric motor 302 receives electricity from the electric power
source 313. The voltage detecting means 341 is a well-known voltage
detecting circuit which outputs detection signal to the control
means 312. The temperature estimating means 340 is a
water-temperature sensor which detects engine coolant temperature.
The ambient temperature around the motor 302 is estimated based on
the engine coolant temperature.
[0168] Also, the control means 312 stores a ratio between the
lock-current and the power source voltage as a function P(T) of the
ambient temperature T. This ratio is referred to as hold-condition
conductance. More specifically, as shown in FIG. 15A, the control
means 312 stores the ambient temperature and the hold-condition
conductance as a table data of "T" and "P(T)".
[0169] The control means 312 applies the estimation value of the
ambient temperature to the function P(T) to compute the
hold-condition conductance. The control means 312 computes an
estimation value "Iss" of the lock-current by multiplying the
hold-condition conductance and the detection value of the power
source voltage.
[0170] The threshold "Ithr" is defined in such a manner as not to
exceed an upper value which is obtained by multiplying "Iss" and
"Ia/Ib".
[0171] Furthermore, the control means 312 corrects the function
P(T) based on the detected electric current, the estimated ambient
temperature around the motor 302, and the detected power source
voltage. Specifically, the detected value of the lock-current is
divided by the detected value of the power source voltage so that
the actual measured value "P" of the hold-condition conductance is
computed. Based on the actual measured value "P", the table data of
the function P(T) is updated.
[0172] For example, in a case that the estimated value of the
ambient temperature around the motor 302 is Ts.degree. C.
(0.degree. C.<Ts<20.degree. C.), a ratio between a difference
(Ts-0) and a difference (20-Ts) is defined as "s:(1-s)"
(0<s<1), the hold-condition conductance obtained based on
not-updated P(0) and P(20) is denoted by P(Ts), and the difference
between "P" and "P(Ts)" is denoted by ".DELTA.P(Ts)".
[0173] In this case, after a weighting is performed with respect to
not-updated P(0) and P(20) according to Ts.degree. C., the updated
P(0) and P(20) are expressed as follows:
Updated P(0)=not-updated P(0)+k(1-s).DELTA.P(Ts)
Updated P(20)=not-updated P(20)+ks.DELTA.P(Ts)
wherein k=1/(2s.sup.2-2s+1).
[Advantages of Fifth Embodiment]
[0174] According to the fifth embodiment, the driving apparatus 301
is provided with a temperature estimating means 340 which estimates
the ambient temperature around the electric motor 302, a voltage
detecting means 341 which detects the power source voltage. The
control means 312 computes the hold-condition conductance based on
the table data which shows a relation between the ambient
temperature around the motor 302 and the hold-condition
conductance. Further, the estimation value "Iss" of the
lock-current is computed by multiplying the hold-condition
conductance and the detection value of the power source voltage.
Thereby, the estimation value "Iss" of the lock-current can be
computed in view of the thermal characteristic.
[0175] Further, the control means 312 corrects the table data based
on the detected value of the electric current supplied to the motor
302, the estimation value of the ambient temperature around the
motor 302 and the detection value of the power source voltage.
Thereby, even if the characteristics of the electric motor 302 are
varied with age, the hold-condition conductance in the table data
can be updated with high accuracy. Even if the characteristics of
the electric motor 302 are varied with age, the lock-current can be
estimated with high accuracy.
Sixth Embodiment
[0176] According to a sixth embodiment, as shown in FIGS. 16A and
16B, the control means 312 outputs PWM-signals to four switching
elements 325 of a driving circuit 314 so that the energization of
the motor 302 is controlled. A sampling frequency at which the
control means 312 obtains the detection values from the current
detecting means 311 is greater than a value which is obtained by
dividing the frequency of the PWM-signals by a duty ratio of the
PWM-signals. Thereby, since the detection value of the electric
current is surely obtained during ON-period of the PWM-signals, it
can be avoided that the detection value of the electric current is
obtained only during OFF-period of the PWM-signals.
[0177] The control means 312 does not use detection value which is
lower than a reference value, when executing processings shown in
FIGS. 4-6. Thus, erroneous determinations can be avoided.
[Modification]
[0178] The driving apparatus 301 is not limited to the above
embodiments. For example, it can be determined whether the
rotational position of the valve 303 normally reaches the full-open
position in a case that the valve 303 rotates from the full-close
position toward the full-open position.
[0179] The hold condition can be generated at a middle position
between the fuel-open position and the full-close position. The
driving apparatus can be applied to a throttle valve control
apparatus or an EGR gas control apparatus.
[0180] In the above embodiments, the valve 303 is a butterfly
valve. Alternatively, the valve 303 may be a poppet valve or a
needle valve.
[0181] In a case that the valve 303 is a poppet valve, the driving
apparatus 301 controls a linear movement of the poppet valve.
* * * * *