Information
-
Patent Grant
-
6808471
-
Patent Number
6,808,471
-
Date Filed
Thursday, May 8, 200321 years ago
-
Date Issued
Tuesday, October 26, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 477 107
- 123 198 F
- 123 332
- 123 376
- 123 403
- 123 40652
- 123 481
-
International Classifications
-
Abstract
Methods and apparatus are provided for ensuring that a throttle increase accompanying a change in the number of active cylinders of an internal combustion engine will not occur too long with more than a selected fraction of all the cylinders activated, so as to not startle a driver. The apparatus comprises an electronic controller that generates the throttle increase if less than all the cylinders are requested to be activated. A determination is made as to whether the number of cylinders being fueled is equal to or less than the selected fraction. A timer is started if the number of cylinders being fueled is greater than the selected fraction. The throttle increase is turned off if the amount of time measured by the timer exceeds a threshold before the number of cylinders being fueled becomes either less than or equal to the selected fraction.
Description
FIELD OF THE INVENTION
The present invention generally relates to electronic throttle security, and more particularly relates to such security for internal combustion engines having electronic throttle control systems for enabling cylinder activation and deactivation.
BACKGROUND OF THE INVENTION
Those skilled in the art of internal combustion engine design understand that control of internal combustion engines preferably includes engine cylinder activation and deactivation or displacement on demand to improve fuel economy. This engine control strategy generally involves reducing the number of active engine cylinders as a reduced amount of power is requested from the engine, and the valves of deactivated cylinders are generally configured to improve fuel efficiency. For example, the valves of the deactivated cylinders are at least substantially closed to reduce pumping losses. However, in this example, after some of the cylinders are at least substantially closed to reduce pumping losses, the remaining active cylinders are generally configured to receive a throttle increase to maintain the same level of output torque from the engine. Furthermore, when the power requirements increase a sufficient amount, the deactivated cylinders are reactivated and the throttle level is altered so that the engine continues to deliver the desired amount of power.
It is desirable for the adjustments of the control strategy to occur with minimal, and preferably no awareness of the engine operator. This statement is particularly true in the case of an automobile engine operating under the control of an operator that is providing a substantially constant accelerator pedal position. In this situation, the engine throttle is preferably adjusted a predetermined amount in response to cylinder deactivation and preferably adjusted a predetermined amount in response to cylinder reactivation. While these control strategies for internal combustion engines provide the proper engine power and improve fuel efficiency, other improvements are continually sought.
In view of the foregoing, it should be appreciated that there is a need to provide methods and apparatus for providing security for electronically controlled cylinder activation and deactivation. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention, brief summary of the invention, abstract, and appended claims, taken in conjunction with the accompanying drawings and this background of the invention of the invention.
BRIEF SUMMARY OF THE INVENTION
In accordance with the teachings of the present invention security methods and apparatus are provided for ensuring that a throttle increase accompanying a decrease in the number of active cylinders of an internal combustion engine will be limited to a predetermined threshold period with more than a selected fraction of all the cylinders of the engine being activated. The apparatus comprises an electronic controller that generates the throttle increase if less than all the cylinders are requested to be activated. A query is made to determine if the number of cylinders being fueled is equal to or less than the selected fraction. A timer is started if the number of cylinders being fueled is greater than the selected fraction of all the cylinders. The throttle increase is turned off if the amount of time measured by the timer exceeds the predetermined threshold before the number of cylinders being fueled becomes either less than or equal to the selected fraction.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like reference numbers denote like elements, and
FIG. 1
is a schematic diagram of a vehicle drive train having a security system for cylinder deactivation and reactivation;
FIG. 2
is a flow chart of a software program for use with the system of
FIG. 1
in accordance with an embodiment of the invention;
FIG. 3
is a timing diagram indicating a normal mode of operation of the security system of
FIGS. 1 and 2
; and
FIG. 4
is a timing diagram indicating a fault mode of operation of the security system of FIGS.
1
and
2
.
DETAILED DESCRIPTION OF THE INVENTION
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.
Referring to
FIG. 1
, a vehicle drive train
10
is generally illustrated that includes an internal combustion engine
12
coupled to transmission
14
, which in turn is coupled by drive shaft
16
and differential
18
to a pair of driven wheels
20
a
-
20
b
. The position of a throttle
22
disposed within a manifold
21
of engine
12
is controlled to enable engine
12
to produce the desired output torque for driving wheels
20
a
-
20
b
. In the illustrated embodiment, throttle
22
is mechanically de-coupled from driver accelerator pedal
23
and instead is positioned by electric motor
24
under the direction of powertrain control module (PCM)
26
that also controls the operation of engine
12
and transmission
14
. PCM
26
includes electronic throttle control (ETC)
27
for operating throttle
22
. ETC
27
provides signals to motor
24
. PCM
26
is microprocessor based and includes various logic units and memories such as ROM and RAM.
PCM
26
operates in response to a number of inputs. These inputs include an engine speed signal (Ne) on line
28
, a vehicle speed signal (Nv) on line
30
, an accessory loading signal (ACC) on line
34
, a Throttle Position Feedback signal (TPS) on line
36
, a Manifold Absolute Pressure (MAP) signal on line
38
and Pedal Position Sensor signal (PPS) on line
39
. These inputs are provided by conventional sensors such as illustrated shaft speed sensors
40
,
42
and accelerator pedal position sensor
44
. In general, ETC module
27
activates motor
24
to position throttle
22
in response to the positioning of accelerator pedal
23
, but various other functions such as idle speed control, engine governor control, cruise control and torque reduction are also provided for providing the ETC function in a known manner. Additionally, PCM
26
controls conventional spark control device
50
and other fuel control device
52
, which are coupled to engine
12
.
More specifically, internal combustion engine
12
utilizes the PCM/ETC functions provided by system
26
to adjust the fuel, the spark and the amount of airflow through intake manifold
21
in response to sensor monitored operator variations of accelerator pedal
23
. Operator throttle adjustment is typically accomplished using an accelerator-input mechanism, such as a foot pedal
23
, joystick, hand pedal, lever or track ball. The input mechanism is mechanically coupled to sensors in block
44
that in turn provide PPS control signals having magnitudes indicative of the accelerator position to the ETC module
27
. In response, PCM
26
generates additional electrical control signals for enabling the hardware of the vehicle engine to provide the desired operating level requested by the driver as indicated by the accelerator-input mechanism
23
. Such ETC systems provide numerous advantages such as reduced costs, improved simplicity, engine noise reduction, throttle command conditioning for emissions reduction, and/or torque based control functions.
DEAC system
54
provides cylinder activation, deactivation and reactivation to improve a number of operating parameters, such as fuel economy. This is generally accomplished by shutting off or deactivating a predetermined number of the cylinders of engine
12
when the power requirements of the engine are at or below a predetermined lower power level (i.e., the power level is too low) and reactivating the cylinders when the power requirements sufficiently are at or exceed a predetermined upper power level. As can be appreciated by those of ordinary skill in the art, the predetermined power levels can be determined according to any number of techniques. Ideally, the operator of engine
12
or driver of a vehicle including engine
12
is not aware of these transitions. Engine
12
has a predetermined number of cylinders and a selected fraction of this number is operated when deactivation reaches a steady state. For instance, if engine
12
has eight cylinders, which is a well known V8 configuration, and the fraction is one half, then engine
12
could be operated on all eight cylinders when the need for power is high (i.e., the power level is at or exceeds the predetermined upper power level). In addition, the engine
12
could transition to eventually operate on only four cylinders when the need for power is sufficiently low (i.e., at or below the predetermined low level). Engine
12
could also have twelve cylinders. In this case, engine
12
could run on eight, six or four cylinders depending on the power demand requirements, for instance. In any event, the valves of any deactivated cylinders are at least partially closed and preferably completely closed.
DEAC system
54
is coupled to monitor engine
12
and transmission
14
through respective lines
56
and
57
to enable DEAC
54
to provide control signals to PCM
26
through line
58
. When some of the cylinders of engine
12
are shut off, the other active cylinders of the engine are run in response to a higher opening of throttle
22
referred to herein as THROTTLE OFFSET. This action maintains substantially the same level of output torque being delivered through transmission
14
and differential
18
to wheels
20
a
and
20
b
. It is desirable for the larger opening of throttle
22
to occur with minimal and preferably, no action or even awareness by the operator of the engine of the cylinder deactivation event. In addition, it is desirable for the operator to have minimal awareness of cylinder reactivations. To ensure a seamless transition, throttle
22
should be opened at a time slightly before the cylinders are in a deactivated mode. The system preferably avoids the opening of throttle
22
to provide the THROTTLE OFFSET without verification that fuel is shut off to at least some of the cylinders.
Engine
12
could have any number of cylinders greater than one. For purposes of illustration, engine
12
is assumed the aforementioned V8, which is operated on four cylinders when conditions are correct for cylinder deactivation. DEAC
54
provides the THROTTLE OFFSET during the time the cylinder deactivation logic is requesting the throttle to be opened, but the THROTTLE OFFSET is allowed to continue if half or less of the fuel injectors are disabled before a predetermined threshold period (or time limit threshold) is met or exceeded.
Referring to
FIG. 2
, a method
60
is illustrated that is preferably conducted by the PCM
26
. However, the method can be conducted by other electronic controllers, individually or in combination. The timing diagrams
62
and
64
respectively of FIG.
3
and
FIG. 4
illustrate the operation of apparatus
10
of FIG.
1
and method
60
of
FIG. 2
Abscissa axis
66
of
FIG. 3
is the time between times T
0
and T
18
. Time, TO on axis
66
corresponds to BEGIN step
68
of method
60
.
DEAC MODE REQUEST graph
70
of
FIG. 3
is initially assumed to be requesting that all eight cylinders receive fuel as indicated by level
72
. Accordingly, eight cylinders are being fueled between times T
0
and T
1
as indicated by level
74
of graph
76
which indicates the NUMBER OF CYLINDERS BEING FUELED. Decision block or method step
78
of
FIG. 2
determines if DEAC
54
is requesting activation of less than all the cylinders. Since the answer is NO between T
0
and T
1
, the TIMER is RESET as indicated by block
85
. Accordingly, OFFSET FUEL ON FLAG
86
is FALSE as indicated by block
86
of FIG.
2
and level
88
of OFFSET FUEL ON FLAG waveform
90
of FIG.
3
. OR block
92
of
FIG. 2
responds to FALSE level
88
to ensure that the THROTTLE OFFSET is OFF per block
94
to provide level
96
of THROTTLE OFFSET waveform
98
of FIG.
3
. Hence, engine
12
does not receive the THROTTLE OFFSET fuel increase between T
0
and T
1
.
Referring to
FIG.1
, DEAC
54
receives input on line
57
identifying which gear is being employed in transmission
14
. Deactivation of any of the cylinders is not desirable if transmission
14
is in a predetermined lower gear or a predetermined set of lower gears (i.e., the gear or gears is too low), such as either the first or the second gear, for instance. If the gear is too low for cylinder deactivation to be desirable, then the NO decision from block
100
of
FIG. 2
causes block
102
to provide a GEAR STATE ENABLE FLAG having a FALSE indication to OR block
92
. This causes the THROTTLE OFFSET request to be OFF as indicated by block
94
. Alternatively, if the gear is a gear other than the predetermined lower gear or gears, then the YES from decision block
100
causes the GEAR STATE ENABLE FLAG to be TRUE as indicated by block
104
of FIG.
2
. For purposes of the following discussion herein, it is assumed that the gear level is correct for deactivation resulting in the TRUE GEAR STATE ENABLE FLAG of block
104
.
At time T
1
of
FIG. 3
, DEAC
54
requests deactivation of half of the predetermined maximum number of cylinders as indicated by level
105
of waveform
70
. The number of cylinders being fueled then transitions from eight to seven as indicated by level
106
of waveform
76
of FIG.
3
. Accordingly, decision step
78
of
FIG. 2
now provides a YES. As a result, the OFFSET FUEL ON FLAG is TRUE as indicated by block
108
and level
109
of waveform
90
. AND block
112
responds to the TRUE from block
108
and the TRUE from block
104
to provide the THROTTLE OFFSET ON SIGNAL of block
113
as indicated by level
114
of waveform
98
of FIG.
3
. Level
114
results in an increased amount of fuel being supplied to the active cylinders.
THROTTLE OFFSET ON signal
114
of block
113
of
FIG. 2
initiates the decision step of block
115
which determines if the number of fueled cylinders is less than or equal to one half the number of all the cylinders, for instance. Since seven, six and five as indicated by respective levels
106
,
116
and
117
of waveform
76
of
FIG. 3
are all greater than four the answer to decision
115
is NO between times T
1
and T
4
. Accordingly, the START TIMER signal of block
118
causes OFFSET FUEL OFF TIMER waveform
119
to ramp from reset level
120
to begin measuring time from T
1
as indicated by ramp
121
of waveform
119
.
At time T
4
, the number of cylinders being fueled equals four as indicated by level
125
of waveform
76
. Accordingly, the decision from block
115
becomes YES which RESETS the TIMER as indicated by block
126
of
FIG. 2
to cause transition
128
of waveform
119
back to reset level
120
. The amount of time from T
1
to T
4
is less than a predetermined or selected THRESHOLD amount of time (i.e., the predetermined threshold period), T
5
. Hence, the answer of decision block
130
is NO which allows the OFFSET FUEL ON FLAG to continue to be TRUE as indicated by block
108
. The above sequence of events represents the “normal case” for the operation of the DEAC function. The THRESHOLD time, T
5
may be calibrated or changed in response to monitored parameters.
At time T
6
of
FIG. 3
, DEAC MODE signal
70
changes to and remains at level
130
to facilitate operation in the steady state four cylinder active condition until time T
10
when signal
70
moves to level
132
to indicate a request for reactivation of an additional cylinder. Since activation of all cylinders is not being requested at T
10
, decision block
78
provides a YES so that the OFFSET FUEL ON FLAG continues to be TRUE resulting in THROTTLE OFFSET signal
98
remaining at level
114
. Five cylinders are being fueled between T
10
and T
11
as indicated by level
134
of waveform
76
. Accordingly, at T
10
decision block
115
provides a NO which again provides the START TIMER signal of block
118
and waveform
119
begins ramp
136
. Six, seven and eight cylinders are respectively reactivated at T
11
, T
12
and T
13
as indicated by respective levels
138
,
140
and
142
of waveform
76
.
At T
14
, the system returns to the reactivated eight-cylinder mode as indicated by level
143
of DEAC signal
70
. As a result, decision block
78
becomes NO which causes the TIMER to RESET to level
120
of waveform
119
per block
85
. The NO from block
78
also initiates the FALSE OFFSET FUEL ON FLAG of block
86
which causes waveform
90
to return to level
88
. Accordingly, the THROTTLE OFFSET OFF signal of block
94
causes signal the THROTTLE OFFSET
98
to return to level
96
. Such reactivation occurs is another “normal case” of operation for the DEAC function.
FIG. 4
illustrates a “fault case” for the DEAC function which employs the previously mentioned security method and apparatus. Between T
0
and T
3
, the waveforms of
FIG. 4
are the same as in
FIG. 3
indicating the same method as previously described for FIG.
2
. However, at T
3
waveform
76
representing the number of cylinders being fueled undesirably remains at six cylinders as indicated by level
116
rather than dropping to five cylinders. Accordingly, system
10
is now operating in the abnormal or fault mode. Since the NUMBER OF FUELED CYLINDERS does not become equal to or less than four, TIMER RESET
126
of
FIG. 2
is not enabled by decision block
115
. Thus, OFFSET FUEL OFF TIMER waveform
119
portion
150
of
FIG. 4
continues to ramp through the time THRESHOLD T
5
. As a result, decision block
130
provides a YES which enables the FALSE FUEL ON ENABLE FLAG of block
86
which causes signal
90
to drop to level
88
at T
5
. As a result, the THROTTLE OFFSET
98
returns to level
96
at T
5
to remove the extra fuel being applied to the activated cylinders of engine
112
.
Furthermore, referring again to
FIG. 3
, if only seven cylinders are reactivated during the reactivation sequence, then ramp
136
of waveform
119
would continue on to form dashed portion
152
which would cross time THRESHOLD T
15
. This event also would result in a YES from decision block
130
causing the OFFSET FUEL ON FLAG to become FALSE and the THROTTLE OFFSET also becoming FALSE. Hence, the extra fuel would again be terminated.
The previously described embodiments of the invention therefore provide a security apparatus and method which ensure that the higher THROTTLE OFFSET fuel level
114
will not be used for a long enough time with more than a selected fraction of the predetermined maximum number of cylinders. For instance, the invention provides security to ensure that THROTTLE OFFSET
98
is not allowed to remain on at level
114
long enough with more than half of the cylinders enabled.
While the exemplary embodiments have been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that these exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the spirit and scope of the invention as set forth in the appended claims.
Claims
- 1. A security apparatus for an electronic fuel control system in an engine of a vehicle, such apparatus comprising:a predetermined number of cylinders of the engine that are configured for activation and deactivation; a throttle of the engine that is configured to provide a throttle increase based at least in part upon a deactivation of one or more of said predetermined number of cylinders; and an electronic controller that is configured to: generate an increase signal for said throttle if less than all the predetermined number of cylinders is requested to be activated; determine whether a number of said predetermined number of cylinders being activated is equal to or less than a selected fraction; start timing with a timer if the number of said predetermined number of cylinders being activated is greater than the selected fraction; and request termination of said increase signal if the time measured by the timer exceeds a predetermined threshold.
- 2. The apparatus of claim 1 wherein the electronic fuel control system further comprising:means for adjusting said throttle; and a cylinder activation and deactivation system coupled to said means for adjusting said throttle.
- 3. The apparatus of claim 2 being included in a mechanical system having a transmission with a plurality of gears;said cylinder activation and deactivation system being arranged to monitor which of said plurality of gears is being employed by said transmission; and said cylinder activation and deactivation system ensuring that said increase request is generated only if said transmission is in selected ones of said plurality of gears.
- 4. The apparatus of claim 1, wherein the selected fraction is one-half.
- 5. The apparatus of claim 1, wherein the predetermined number of cylinders is eight.
- 6. The apparatus of claim 1, wherein the predetermined number of cylinders is twelve.
- 7. The apparatus of claim 1, wherein said predetermined threshold can be calibrated.
- 8. The apparatus of claim 1, wherein said vehicle is an automobile.
- 9. The apparatus of claim 1, wherein said engine is an internal combustion engine.
- 10. A security method for an electronic fuel control system in an engine of a vehicle having a predetermined number of cylinders, the method comprising the steps of:generating an increase signal for a throttle of the engine if less than all of the predetermined number of cylinders is requested to be activated; determining whether a number of the predetermined number of cylinders being activated is equal to or less than the selected fraction; starting a timer if the number of the predetermined number of cylinders being activated is greater than the selected fraction; and requesting termination of said increase signal if a time measured by said timer exceeds a predetermined threshold.
- 11. The method of claim 10, further comprising the steps of:monitoring which gear is being employed by a transmission having a plurality of gears, said transmission being connected to the engine; and providing the increase signal only if said transmission is employing selected ones of said plurality of gears.
- 12. The method of claim 10, wherein said selected fraction is one-half.
- 13. The method of claim 10, wherein the predetermined number of cylinders is eight.
- 14. The method of claim 10, wherein said predetermined threshold can be calibrated.
- 15. The method of claim 10, wherein said activation of said predetermined number of cylinders comprises fueling.
- 16. The apparatus of claim 10, wherein the predetermined number of cylinders is twelve.
- 17. The apparatus of claim 10, wherein said predetermined threshold can be calibrated.
- 18. The apparatus of claim 10, wherein said vehicle is an automobile.
- 19. The apparatus of claim 10, wherein said engine is an internal combustion engine.
- 20. A security apparatus for an electronic fuel control system in an internal combustion engine of an automobile, such security apparatus comprising:eight cylinders of the engine that are configured for activation and deactivation; a throttle of the engine that is configured to provide a throttle increase based at least in part upon a deactivation of one or more of the eight cylinders; and an electronic controller that is configured to: generate an increase signal for said throttle if less eight cylinders are requested to be activated; determine whether the number of eight cylinders being activated is equal to or less than four; start timing with a timer if the number of eight cylinders being activated is greater than four; and request termination of said increase signal if the time measured by the timer exceeds a predetermined threshold period.
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