BACKGROUND OF THE INVENTION
[0001] The present invention relates to a fuel supply amount controller of an internal combustion
engine that regulating the fuel supply amount, thereby directly or indirectly adjusting
the output torque. Specifically, the present invention relates to a fuel supply amount
controller that, in accordance with a fail-safe limit value set correspondingly to
an operation state of an internal combustion engine, restricts a fuel supply amount
requested for the internal combustion engine. The present invention also pertains
to a method for controlling the controller.
[0002] Japanese Laid-Open Patent Publication No. 2002-39004 discloses an internal combustion
engine that restricts a fuel supply amount, which is a fuel injection amount, using
a fail-safe limit value for performing a fail-safe procedure against errors in the
computation of the fuel injection amount. Specifically, when a specific operational
state, for example, a state in which an accelerator pedal is not depressed, continues
for a standby period, the engine of the publication performs a procedure for restricting
the fuel injection amount in accordance with a fail-safe limit value.
[0003] Therefore, even if a computed fuel injection amount becomes excessive due to garbled
data in a RAM, the excessive fuel injection amount is returned to a value that corresponds
to a state where the accelerator pedal is not depressed at all by releasing the accelerator
pedal.
[0004] A control system is present which requests increase of a fuel injection amount in
order to moderate a shock at the time of shift-down performed by an automatic transmission
under deceleration. When the control system functions after a non-depressed state
of an accelerator pedal continues for a standby time, even if an increase of fuel
injection amount is requested for moderating a shock due to gear shifting is executed
and the request is reflected on the computation of the fuel injection amount, an actual
fuel injection amount is restricted correspondingly to a depression degree of the
accelerator pedal with the a fail-safe limit value at the final stage for setting
the fuel injection amount. Therefore, the fuel injection amount is not increased by
a necessary amount and the shock due to gear shifting may not be sufficiently reduced.
SUMMARY OF THE INVENTION
[0005] Accordingly, it is an objective of the present invention to correspond to a request
for causing the engine to generate output torque required for purposes other than
driving the vehicle.
[0006] To achieve the above-mentioned objective, the present invention provides a controller
for controlling the amount of fuel supplied to an internal combustion engine of a
vehicle. Output torque of the engine is adjusted by regulating the fuel supply amount.
The controller restricts the fuel supply amount, which is requested for the engine,
in accordance with a fail-safe limit value set correspondingly to an operation state
of the engine. The controller includes changing means. When a supplemental fuel injection
amount, which is requested for causing the engine to generate output torque required
for purposes other than driving the vehicle, is set, the changing means causes the
limit value to be equal to or to approach the supplemental fuel injection amount if
the limit value is less than the supplemental fuel injection amount.
[0007] According to another aspect of the invention, a method for controlling the amount
of fuel supplied to an internal combustion engine of a vehicle is provided. Output
torque of the engine is adjusted by regulating the fuel supply amount. The method
includes a step of restricting the fuel supply amount, which is requested for the
engine, in accordance with a fail-safe limit value set correspondingly to an operation
state of the engine. The method further includes steps of setting a supplemental fuel
injection amount for causing the engine to generate output torque required for purposes
other than driving the vehicle; and causing the limit value to be equal to or to approach
the supplemental fuel injection amount when the limit value is less than the supplemental
fuel injection amount.
[0008] Other aspects and advantages of the invention will become apparent from the following
description, taken in conjunction with the accompanying drawings, illustrating by
way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention, together with objects and advantages thereof, may best be understood
by reference to the following description of the presently preferred embodiments together
with the accompanying drawings in which:
FIG. 1 is a block diagram showing an accumulator type diesel engine, an automatic
transmission, and ECUs of the engine and the transmission according to a first embodiment
of the present invention;
FIG. 2 is a flowchart of a fuel injection amount control executed by the engine ECU
of the first embodiment;
FIG. 3 is a graph showing a map for the control shown in FIG. 2;
FIG. 4 is a map for obtaining a supplemental amount eqEctu from a target engine speed
NEt;
FIG. 5 is a map for obtaining a first limit value eqAcgurd for a pedal released state
based on an engine speed NE;
FIG. 6 is a flowchart of synchronization process executed by the engine ECU of the
first embodiment;
FIG. 7 is a timing chart for explaining functions and advantages of the first embodiment;
FIG. 8 is a timing chart for explaining functions and advantages of the first embodiment;
FIG. 9 is a flowchart of a fuel injection amount control executed by an engine ECU
according to a second embodiment of the present invention; and
FIG. 10 is a flowchart of synchronization process executed by an engine ECU according
to a third embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] In the drawings, like numerals are used for like elements throughout.
[0011] A first embodiment according to the present invention will be described below. FIG.
1 is a block diagram showing an accumulator type diesel engine (common-rail diesel
engine) 2, an automatic transmission 4, an ECU (electronic control unit) 6 of the
diesel engine 2 and an ECU 8 of the transmission 4. The diesel engine 2 is mounted
on a vehicle as an automobile engine.
[0012] The diesel engine 2 has cylinders the number of which is, for example, four. A fuel
injection valve is set to the combustion chamber of each cylinder. Fuel raised up.to
a fuel injection pressure is supplied to the fuel injection valves from a common rail.
The fuel is injected into each cylinder by opening each fuel injection valve in accordance
with a command by the engine ECU 6 for a valve opening period corresponding to a fuel
injection amount requested for the diesel engine 2.
[0013] The diesel engine 2 and the automatic transmission 4 are provided with various sensors
10. Specifically, the diesel engine 2 is provided with an accelerator pedal depression
degree sensor, an engine speed sensor, a cylinder-distinguishing sensor, a coolant
temperature sensor, an intake-air temperature sensor, and fuel pressure sensor. The
automatic transmission 4 is provided with a speed sensor. The engine ECU 6 detects
an operation state of the diesel engine 2 and a driving state of a vehicle in accordance
with outputs of various sensors 10. The engine ECU 6 exchanges commands and data with
the transmission ECU 8. The engine ECU 6 controls the combustion state of the diesel
engine 2 through fuel injection amount control in accordance with these commands and
data.
[0014] The automatic transmission 4 is of a torque converter type, which changes speeds
by controlling operations of internal rotational members, for example, various gears
including a planetary gear, a clutch, and brakes. The sensors 10 include a shift position
sensor and a turbine speed sensor set to the automatic transmission 4 in addition
to the above configuration. The transmission ECU 8 detects a request of a driver,
an internal state of the automatic transmission 4 and a driving state of a vehicle
in accordance with the data on an accelerator pedal depression degree ACCP, an engine
speed NE, a shift position, a turbine speed NT, and a vehicle speed V to execute vehicle
speed control for the automatic transmission 4. Moreover, the transmission ECU 8 reads
a coolant temperature and braking state in the data detected by the engine ECU 6.
Furthermore, as described above, the transmission ECU 8 exchanges commands and data
with the engine ECU 6. The transmission ECU 8 executes the speed change control of
the automatic transmission 4 by switching electromagnetic valves of a hydraulic control
circuit 4a in accordance with these commands and data. For example, a gear stage of
the automatic transmission 4 is determined in accordance with a vehicle speed V and
a fuel injection amount (or depression degree of the accelerator pedal ACCP) by using
a previously stored speed-change diagram to switch electromagnetic valves of the hydraulic
control circuit 4a so as to effectuate the decided gear stage.
[0015] The engine ECU 6 and the transmission ECU 8 are respectively mainly constituted by
a microcomputer having a CPU, a ROM, a RAM, a backup RAM, a timer counter, an input
interface, and an output interface.
[0016] Then, in the case of this embodiment, the fuel injection amount control is described
among controls to be executed by the engine ECU 6. FIG. 2 shows a flowchart of the
process. This control is executed as an interrupt at every constant crank angle (every
explosion stroke). A step in the flowchart corresponding to each process is shown
by the letter S.
[0017] When the fuel injection amount control is started, a base injection amount eqBase
is first calculated in accordance with an operation state of the diesel engine 2 by
the above sensors 10 (S102). The base injection amount eqBase is set by correcting
a reference injection amount, that is, a governor injection amount eqgov obtained
from the engine speed NE and depression degree of the accelerator pedal ACCP in accordance
with a map for reference pattern data shown in FIG. 3. For example, when a load such
as air conditioner load is generated on the governor injection amount eqgov, a fuel
injection amount correction corresponding to the load or a correction according to
learned value obtained at the time of idling speed control (ISC) is executed. Moreover,
a correction is executed in which a fuel injection amount requested at the time of
shift-down (described below), that is, a supplemental fuel injection amount eqEctu
is used as the base injection amount eqBase. The base injection amount eqBase is calculated
by executing the above various corrections.
[0018] Then, as shown in the following expression 1, an injection amount before final restriction,
that is, a prefinal injection amount eqPreFinc is calculated (S104).

[0019] As shown in FIG. 3, the maximum injection amount eqFull is a value for setting the
upper limit of a fuel injection amount to be set correspondingly to the engine speed
NE in accordance with the synchronization process (synchronization) to be described
later. MIN () denotes an operator for extracting a minimum value out of numerals enclosed
by parentheses.
[0020] Therefore, the upper limit of the base injection amount eqBase is restricted in accordance
with the expression 1 and set as the prefinal injection amount eqPreFinc.
[0021] Then, it is determined whether a standby time elapses while the depression degree
of the accelerator pedal ACCP is equal to [0], that is, an accelerator pedal is released
(S106). When an accelerator pedal is completely released, it is possible to estimate
that a driver performs a deceleration operation. However, the changing speed of the
base injection amount eqBase is restricted to prevent a shock, for example a deceleration
shock from occurring due to sudden reduction of a fuel injection amount through a
pedal operation. Therefore, even if a deceleration operation is performed by a driver,
a deceleration shock may occur when suddenly decreasing a fuel injection amount by
immediately adding a new restriction to the fuel injection amount. Therefore, a standby
time is set for the determination in step S106.
[0022] When the standby time does not elapse under an accelerator pedal released state (NO
in step 106), the value of the prefinal injection amount eqPreFinc is set to a final
fuel injection amount (final injection amount) eqFinc (S108) and the process is temporarily
ended. Thus, when the final injection amount eqFinc is set, valve-opening control
for the fuel injection valves is executed by the engine ECU 6 so that the amount of
fuel equivalent to the final injection amount eqFinc is injected into the combustion
chamber of the diesel engine 2.
[0023] When the standby time elapses under the accelerator pedal released state (YES in
S106), it is determined whether the supplemental amount eqEctu is set as a requested
fuel injection amount (S110). The supplemental amount eqEctu is a requested fuel injection
amount set in a synchronization process (described later). That is, the supplemental
amount eqEctu is a fuel injection amount to be increased that is set as a request
value at the timing in a shift-down fuel amount increasing period after increase of
a fuel injection amount is requested at the time of shift-down by the transmission
ECU 8. The supplemental amount eqEctu is a fuel injection amount set to prevent a
deceleration shock at the time of shift-down. Specifically, the supplemental amount
eqEctu is set in accordance with the target engine speed NEt set correspondingly to
shift-down control in accordance with the map shown in FIG. 4.
[0024] In this case, when the supplemental amount eqEctu is not set (NO in S110), the final
injection amount eqFinc is calculated in accordance with the following expression
2 (S112) and the process is temporarily ended.

[0025] A fuel-injection-amount limit value when the accelerator pedal is released, that
is, a first limit value eqAcgurd is a fail-safe limit value for preventing an excessive
fuel amount from being injected when a standby time elapses under the accelerator
pedal released state. Specifically, the first limit value eqAcgurd is set in accordance
with the engine speed NE by using the map shown in FIG. 5. The first limit value eqAcgurd
is set to 0 (mm
3/stroke) or less in order to cut fuel at the engine high-speed side. Thereby, the
upper limit of the prefinal injection amount eqPreFinc is restricted in accordance
with the first limit value eqAcgurd and set as the final injection amount eqFinc.
[0026] Therefore, as shown in FIG. 7, the accelerator pedal is released at a high engine
speed at t0 and also after a standby time elapses at t1, a state in which the final
injection amount eqFinc is limited continues at the first limit value eqAcgurd while
the supplemental amount eqEctu is not set. FIG. 7 shows a state in which the prefinal
injection amount eqPreFinc exceeds the first limit value eqAcgurd due to any reason
at t2. However, the final injection amount eqFinc does not exceed the value of the
first limit value eqAcgurd.
[0027] However, when the supplemental amount eqEctu is set (YES in S110), the final injection
amount eqFinc is calculated in accordance with the following expression 3 (S114) and
the process is temporarily ended.

[0028] MAX () denotes an operator for extracting a maximum value out of numerals enclosed
by parentheses.
[0029] Therefore, the prefinal injection amount eqPreFinc is restricted by greater one of
the supplemental amount eqEctu and first limit value eqAcgurd and set as the final
injection amount eqFinc.
[0030] In this case, as shown by the timing chart in FIG. 8, after the engine speed NE rises,
the accelerator pedal is released (ACCP=0) at t10, and the standby time elapses at
t11, the state is kept as described for the above expression 2 while the supplemental
amount eqEctu is not set. That is, the final injection amount eqFinc is limited by
the first limit value eqAcgurd.
[0031] However, when the supplemental amount eqEctu, which is greater than the first limit
value eqAcgurd, is set for shift-down at t12, the final injection amount eqFinc is
limited by the supplemental amount eqEctu in accordance with the above expression
3. Therefore, it is possible to increase a fuel amount so as to prevent a deceleration
shock at the time of shift-down.
[0032] This state is continued during the fuel amount increase period necessary for request
realization and then, the supplemental amount eqEctu returns to an unset state at
t13. Therefore, the final injection amount eqFinc is limited by the first limit value
egAcgurd again as described for the expression 2.
[0033] FIG. 6 shows the synchronization process for setting the maximum injection amount
eqFull and supplemental amount eqEctu. The process is repeatedly executed in the engine
ECU 6 at a short-time period. When the process is started, the maximum injection amount
eqFull is first obtained in accordance with the engine speed NE from a maximum injection
amount eqFull map shown by an alternate long and short dash line by superimposing
the map in FIG. 3 (S202). Then, it is determined whether a fuel amount increase request
is generated at the time of shift-down by the transmission ECU 8 (S204). When the
fuel amount increase request is not generated (NO in S204), the supplemental amount
eqEctu is cleared, that is, an unset state is set (S208) and the process is temporarily
ended.
[0034] When the fuel amount increase request is generated at the time of shift-down (YES
in S204), then it is determined whether the request is generated within a fuel amount
increase period at the time of shift-down (S206). The fuel amount increase period
is a period in which it is necessary to restrain a shock at the time of shift-down
by increasing a torque during a speed change, which is set in accordance with, for
example, the depression degree of the accelerator pedal ACCP, the vehicle speed V,
the turbine speed NT, or the shift state.
[0035] In this case, when the request is not generated in the fuel amount increase period
(NO in S206), the process is temporarily ended without setting the supplemental amount
eqEctu (S208).
[0036] However, when the request is generated in the shift-down fuel amount increase period
t12 to t13 in FIG. 8 (YES in S206), the supplemental amount eqEctu is set in accordance
with the target engine speed NEt by using the above-described map in FIG. 4 (S210).
By setting the supplemental amount eqEctu, the supplemental amount eqEctu is set to
the base injection amount eqBase in step S102 of the fuel injection amount control
process (FIG. 2). Moreover, when YES is determined in step S110, a fail-safe limit
value is raised to the supplemental amount eqEctu in step S114. Therefore, the engine
ECU 6 executes fuel injection according to the supplemental amount eqEctu.
[0037] In the above configuration, steps S204 to S210 of the synchronization process (FIG.
6) correspond to the process by a system for setting a requested fuel supply amount
for output torques other than the torque for driving the vehicle. Steps S110 and S114
of the fuel injection amount control process (FIG. 2) correspond to the process by
fail-safe limit-value changing means.
[0038] The above first embodiment has the following advantage.
[0039] (1) When the supplemental amount eqEctu is set (YES in S110 in FIG. 2), the first
limit value eqAcgurd is compared with the supplemental amount eqEctu by the engine
ECU 6. Then, when eqAcgurd is smaller than eqEctu, the supplemental amount eqEctu
is set as a limit value instead of the first limit value eqAcgurd (S114). Therefore,
when a control system for preventing a shock at the time of shift-down requires the
supplemental amount eqEctu, the supplemental amount eqEctu is realized.
[0040] Thus, it is possible to supply a fuel amount requested by the control system for
setting a requested fuel supply amount for output torques other than the torque for
driving the vehicle and effectively prevent a speed change shock.
[0041] When the control system for preventing a shock at the time of shift-down does not
require the supplemental amount eqEctu (NO in S110), the supplemental amount eqEctu
is not used as a limit value but the final injection amount eqFinc is limited by the
sufficiently small first limit value eqAcgurd (S112). Therefore, no problem occurs
in fail safe.
[0042] A second embodiment of the present invention will now be described. The second embodiment
executes a fuel injection amount control process in FIG. 9 instead of the fuel injection
amount control process (FIG. 2) by the fist embodiment. Other configurations are the
same as those of the first embodiment. The process in FIG. 9 sets a new accelerator
released shift-down fuel injection amount limit value, that is, a second limit value
eqKgurd when setting the supplemental amount eqEctu and uses the second limit value
eqKgurd as a fail-safe limit value at the time of shift-down.
[0043] The processes in steps S302 to S312 in FIG. 9 are the same as the processes in steps
S102 to S112 in FIG. 2. However, the processes (S314 to S318) when the supplemental
amount eqEctu is set (YES in S310) are different from the case of the first embodiment.
[0044] That is, when YES is determined in step S310, it is determined whether eqAcgurd is
smaller than eqEctu (S314). In this case, when eqAcgurd is equal to or greater than
eqEctu, it is not necessary to change first limit value eqAcgurd. Therefore, the final
injection amount eqFinc is calculated in accordance with the expression 2 described
for the first embodiment (S312). Therefore, the final injection amount eqFinc is limited
by the first limit value eqAcgurd.
[0045] However, when eqAcgurd is smaller than eqEctu (YES in S314), the second limit value
eqKgurd is calculated in accordance with the following expression 4 (S316).

[0046] In this expression, a limit value increase amount Deq is set as shown in the following
expression 5.

[0047] In this expression, the coefficient k ranges between 0 and 1 (both excluded) and
it serves as a coefficient for setting the second limit value eqKgurd so as to meet
the inequality eqAcgurd<eqKgurd<eqEctu. For example, k is set to 0.5.
[0048] Although the second limit value eqKgurd thus obtained is smaller than the supplemental
amount eqEctu, it is set to a value greater than the first limit value eqAcgurd.
[0049] Then, as shown in the following expression 6, the final injection amount eqFinc is
calculated (S318).

[0050] Thus, the prefinal injection amount eqPreFinc is restricted by the second limit value
eqKgurd in accordance with the expression 6 and set as the final injection amount
eqFinc.
[0051] In the above configuration, steps S310, S314, S316, and S318 of the fuel injection
amount control process (FIG. 9) correspond to the process by fail-safe limit-value
change means.
[0052] The above-described second embodiment has the following advantage.
[0053] (2) When the supplemental amount eqEctu is set (YES in S310 in FIG. 9), the first
limit value eqAcgurd is compared with the supplemental amount eqEctu (S314). When
eqAcgurd is smaller than eqEctu (YES in S314), the second limit value eqKgurd, which
is closer to the supplemental amount eqEctu than the first limit value eqAcgurd is
to the supplemental amount eqEctu, is set as a limit value (S316).
[0054] Therefore, when the control system for preventing a speed change shock at the time
of shift-down requires the supplemental amount eqEctu, a fuel injection amount can
be realized which is closer to the supplemental amount eqEctu than the first limit
value eqAcgurd. Therefore, it is possible to restrain a speed change shock.
[0055] The shift-down fuel amount increase period determined in step S206 of the synchronization
process (FIG. 6) does not always accurately coincide with a period in which a speed
change shock actually occurs but a time lag may occur between the both periods. Thereby,
the supplemental amount eqEctu may be set to the base injection amount eqBase in the
period in which it is actually unnecessary to increase a fuel amount for the shift-down.
[0056] In this case, according to the second embodiment, the final injection amount eqFinc
does not increase up to the supplemental amount eqEctu, but the second limit value
eqKgurd becomes the upper limit. Therefore, it is possible to restrain a fuel injection
amount for the above time lag.
[0057] When the control system for preventing a shock at the time of shift-down does not
require the supplemental amount eqEctu (NO in S310) or eqAcgurd is equal to or greater
than eqEctu (NO in S314), the second limit value eqKgurd is not used as a limit value.
Therefore, the final injection amount eqFinc is limited by the sufficiently small
first limit value eqAcgurd (S312). Therefore, no problem occurs in fail safe.
[0058] A third embodiment of the present invention will now be described. This embodiment
executes the synchronization process in FIG. 10 instead of the synchronization process
by the first embodiment (FIG. 6). Other configurations are the same as those of the
first embodiment. The process in FIG. 10 limits the supplemental amount eqEctu by
a shift-down injection amount limit value, that is, a maximum supplemental amount
eqEctuMax.
[0059] The processes in steps S402 to S408 in FIG. 10 are the same as the processes in steps
S202 to S208 in FIG. 6. However, the processes (S410 to S416) in the shift-down fuel
amount increase period (YES in S406) are different from that of the first embodiment.
[0060] That is, when YES is determined in step S406, pre-restriction shift-down injection
amount eqPreEctu is set in accordance with the target engine speed NEt by using a
map same as the map in FIG. 4 described for the first embodiment (S410). Then, it
is determined whether the eqPreEctu is equal to or smaller than the maximum supplemental
amount eqEctuMax to which the maximum fuel injection amount required to prevent a
shock at the time of shift-down is set (S412).
[0061] When eqPreEctu is equal to or smaller than eqEctuMax (YES in S412), the value of
the eqPreEctu is directly set to the supplemental amount eqEctu (S414) and the process
is temporarily ended. Therefore, the above case is the same as the case of obtaining
the supplemental amount eqEctu in accordance with the map in FIG. 4 in the first embodiment.
[0062] However, when eqPreEctu is greater than eqEctuMax (NO in S412), it is discovered
that an excessive value is set to the eqPreEctu due to any cause such as an error
of data communication between the engine ECU 6 and the transmission ECU 8. Therefore,
the maximum supplemental amount eqEctuMax is set to the supplemental amount eqEctu
(S416) and the process is temporarily ended. Thus, the supplemental amount eqEctu
is limited by the maximum supplemental amount eqEctuMax. Thereby, the supplemental
amount eqEctu does not become excessive also in step S114 of the fuel injection amount
control process (FIG. 2). Then, an excessive value is not set to the final injection
amount eqFinc.
[0063] In the above configuration, the maximum supplemental amount eqEctuMax corresponds
to the maximum requested fuel injection amount and steps S404 to S416 of the synchronization
process (FIG. 10) correspond to processes by the control system for setting a requested
fuel supply amount for output torques other than the torque for driving the vehicle.
[0064] The above third embodiment has the following advantages.
[0065] (3) Advantage same as the advantage (1) of the first embodiment.
[0066] (4) Since the supplemental amount eqEctu is also limited and prevented from taking
an excessive value, the fail-safe in the fuel injection amount control process (FIG.
2) becomes more reliable.
[0067] The invention may be embodied in the following forms.
[0068] The third embodiment is an example in which the synchronization process in FIG. 10
is combined with the fuel injection amount control process in FIG. 2. However, it
is also allowed to combine the synchronization process in FIG. 10 with the fuel injection
amount control process in FIG. 9. Thereby, both advantages of the second and third
embodiments are obtained.
[0069] In the above embodiments, a fuel supply system uses a common-rail-type diesel engine.
However, it is also allowed to use a diesel engine using the distribution-type, in-line-type,
or other-type fuel injection pump. Moreover, the present invention may be applied
to an engine other than a diesel engine. For example, the present invention may be
applied to an in-cylinder-injection-type gasoline engine when controlling the engine
by adjusting a gasoline injection amount at the time of stratified charge combustion.
[0070] For a gasoline engine, it is allowed to calculate a fuel injection amount in accordance
with the depression degree of the accelerator pedal ACCP and the engine speed NE,
as the case of the above-described map in FIG. 3. Moreover, it is allowed to calculate
a fuel injection amount in accordance with the engine speed NE and a throttle opening
degree, which is the opening degree of a throttle valve.
[0071] As described above, the output torque of an internal combustion engine is directly
adjusted by adjusting a fuel supply amount. Moreover, in the case of a gasoline engine,
it is allowed to calculate a fuel injection amount in accordance with an intake air
amount and the engine speed NE. That is, it is allowed to adjust indirectly the output
torque of an internal combustion engine by adjusting a fuel supply amount.
[0072] The present examples and embodiments are to be considered as illustrative and not
restrictive and the invention is not to be limited to the details given herein, but
may be modified within the scope and equivalence of the appended claims.
1. A controller for controlling the amount of fuel supplied to an internal combustion
engine of a vehicle, wherein output torque of the engine is adjusted by regulating
the fuel supply amount, wherein the controller restricts the fuel supply amount, which
is requested for the engine, in accordance with a fail-safe limit value set correspondingly
to an operation state of the engine, the controller being
characterized by:
changing means, wherein, when.a supplemental fuel injection amount, which is requested
for causing the engine to generate output torque required for purposes other than
driving the vehicle, is set, the changing means causes the limit value to be equal
to or to approach the supplemental fuel injection amount if the limit value is less
than the supplemental fuel injection amount.
2. The controller according to claim 1, characterized in that the changing means uses the supplemental fuel injection amount as the limit value.
3. The controller according to claim 1 or 2, characterized in that the limit value is set when a state in which an accelerator pedal of the vehicle
is not depressed continues for a predetermined standby period.
4. The controller according to claim 1 or 2, characterized in that the limit value is set when a state in which a throttle valve of the vehicle is fully
closed continues for a predetermined standby period.
5. The controller according to any one of claims 1 to 4, characterized in that the supplemental fuel injection amount is limited to be no more than a predetermined
maximum value.
6. The controller according to any one of claims 1 to 5, characterized in that the supplemental fuel injection amount is set for moderating a shock, which is produced
when gear shifting of an automatic transmission of the vehicle is executed.
7. The controller according to any one of claims 1 to 6, characterized in that the supplemental fuel injection amount is set for moderating a deceleration shock,
which is produced when gear shifting of an automatic transmission of the vehicle is
executed.
8. A method for controlling the amount of fuel supplied to an internal combustion engine
of a vehicle, wherein output torque of the engine is adjusted by regulating the fuel
supply amount, the method being
characterized by:
restricting the fuel supply amount, which is requested for the engine, in accordance
with a fail-safe limit value set correspondingly to an operation state of the engine;
setting a supplemental fuel injection amount for causing the engine to generate output
torque required for purposes other than driving the vehicle; and
causing the limit value to be equal to or to approach the supplemental fuel injection
amount when the limit value is less than the supplemental fuel injection amount.
9. The method according to claim 8, characterized in that the limit value is set when a state in which an accelerator pedal of the vehicle
is not depressed or a state in which a throttle valve of the vehicle is fully closed
continues for a predetermined standby period.
10. The method according to claim 8 or 9, characterized in that the supplemental fuel injection amount is set for moderating a shock, which is produced
when gear shifting of an automatic transmission of the vehicle is executed.