CA2043195C - Fuel injection quantity control system for starting a two-cycle engine - Google Patents
Fuel injection quantity control system for starting a two-cycle engineInfo
- Publication number
- CA2043195C CA2043195C CA 2043195 CA2043195A CA2043195C CA 2043195 C CA2043195 C CA 2043195C CA 2043195 CA2043195 CA 2043195 CA 2043195 A CA2043195 A CA 2043195A CA 2043195 C CA2043195 C CA 2043195C
- Authority
- CA
- Canada
- Prior art keywords
- injection quantity
- engine
- subtrahend
- fuel injection
- setting means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/02—Engines characterised by their cycles, e.g. six-stroke
- F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
- F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two
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- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
A fuel injection quantity control system is for starting a two-cycle engine.
The control system calculates an initial fuel injection quantity by correcting abasic fuel injection quantity according to a time factor which is determined depending on a cranking time. The time factor is differently set for a first engine start operation and second or later engine start operation.
The control system calculates an initial fuel injection quantity by correcting abasic fuel injection quantity according to a time factor which is determined depending on a cranking time. The time factor is differently set for a first engine start operation and second or later engine start operation.
Description
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Title of the Invention FUEL INJECTION QUANTITY CONTROL SYSTEM FOR
STARTING A TWO-CYCLE ENGINE
Background of the Invention (1 ) Field of the Invention The present invention relates to a system of controlling the fuel injection quantity for starting a two-cycle engine, and particularly to a fuel injection quantity control system which can effectively start a two-cycle engine such as a s"o..."~ 'e engine to be used in cold climate conditions. After a failure in starting the engine, the system optimizes a fuel injection quantity for securelyrestarting the engine.
(2) Description of the Related Art Two-cycle engines for motorcycles and sl1o..,l, bi'vsl particularly those used in cold climate conditions frequently employ a fuel supply system of electronically controlled fuel injection type using a fuel injection valve. (Refer to, for example, Japanese Unexamined Patent Publication No. 63-255543.) This sort of system provides the intake manifold of each cylinder with a fuel injection valve to simultaneously inject fuel to all cylinders.
The fuel injection quantity control system of electronically controlled fuel injection type sets a slightly larger fuel injection quantity in starting a two-cycle engine than in normally driving the engine, thereby easily starting the engine.
When an ignition switch is turned to a start position for cranking the engine, the system controls the fuel injection valve to inject fuel in a quantity (a fuel injection pulse width) expressed with the following equation:
TILN = TlLNTwK x KLN x KLT
where TILN is a fuel injection pulse width for starting the engine, TILNTwK a basic fuel injection quantity for starting the engine, KLN a rotational speed factor, and KLT a time factor.
The basic fuel injection quantity TILNTwK which differs depending on engine temperature is stored in advance in a memory. The rotational speed factor KLN changes depending on cranking speed. The time factor KLT
changes depending on cranking time.
As shown in Fig. 9, the time factor KLT is updated at a predetermined interval of time (for example, 65 ms) by subtracting a predetermined value LT from a last time factor KLT (1 at first).
Namely, the time factor KLT is successively updated accor~ing to KLT =
KLT - ~KLT and decl~asecl according to elapsing time as shown in Fig. 10.
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Figure 11 shows the problem of the above-mentioned fuel injection quantity control system for starting a two-cycle engine. In the figure, the engine was started and once driven to a complete combustion state.
Thereafter, due to a certain reason, a speed N of the engine dropped, and the engine stalled. The engine was then restarted. In cold conditions, however, the engine speed N hardly rose to fail restarting.
The reason of this failure is because the time factor KLT is newly set for every starting operation, thereby setting a large time factor in correcting a fuel injection quantity for restarting the engine. As a result, excessive fuel is injected to the engine. Namely, the actual fuel injection quantity exceeds the required fuel injection quantity of the engine, thereby setting an air-fuel ratio to be too dense.
Summary of the Invention In view of the problem of the conventional system, an object of the invention is to securely restart an engine after a failure in starting the engine by optimizing a correction factor of the fuel injection quantity according to cranking time in such a way that the actual fuel injection quantity may not exceed the required fuel injection quantity of the engine, and that an air-fuel ratio may not be too dense.
To achieve the object, the invention provides, as shown in Fig. 1, a fuel injection quantity control system for starting a two-cycle engine, comprising:
a fuel injection valve;
an engine operation detecting means including a start detecting means for detecting the start of the engine according to the cranking operation of theengine, a cranking time detecting means for detecting cranking time, and an engine temperature detecting means for detecting the engine temperature;
a basic injection quantity setting means for setting the basic fuel injection quantity for starting the engine according to the engine temperature;
a time factor setting means for updating and setting, at predetermined intervals, a time factor to be suitable for the cranking time by subtracting a predetermined subtrahend from a last time factor;
a first subtrahend setting means for setting a first subtrahend to be applied to the time factor;
a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor;
a start judging means for judging, when an engine start is detected, whether it is a first engine start, or a second or later one;
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a selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the second subtrahend setting means when the start judging means provides a signal indicating the second or later engine start; and an initial injection quantity calculating means for calculating an initial fuel injection quantity according to the basic injection quantity provided by the basic injection quantity setting means and a time factor prepared in the time factor setting means, the time factor setting means preparing the time factor according to a subtrahend which is provided by the selected one of the subtrahend setting means.
In this way, the present invention employs two subtrahend setting means for setting a subtrahend to be applied to a time factor for correcting thebasic fuel injection quantity according to a cranking time. In restarting the engine, the invention selects one of the subtrahend setting means which provides a larger subtrahend than the other which is used for starting the engine for the first time. Based on the basic fuel injection quantity and the time factor determined according to the subtrahend, the invention calculates a fuel injection quantity for restarting the engine.
As mentioned above, the invention employs two subtrahend setting means. To restart the engine, the invention corrects the basic fuel injection quantity according to a subtrahend provided by one of the subtrahend setting means which is larger than that provided by the other which is used for a first engine starting operation. Even if the engine stalls due to a certain reason after it started and reached a complete combustion state, the invention can restart the engine with an actual fuel injection quantity not exceeding a required fuel injection quantity and with an air-fuel ratio being not too dense. As a result, the invention can surely restart the engine, thereby improving starting performance.
A fuel injection quantity for starting an engine is calculated by finding TILN with a basic fuel injection quantity TILNTwK and a time factor KLT
according to the following equation:
TILN = TlLNTwK x KLT
The fuel injection quantity may be calculated not only by correcting the basic fuel injection quantity TILNTwK with the time factor KLT but also by correcting the basic fuel injection quantity with a rotational speed factor KLN
set by a rotational speed factor setting means according to a cranking speed.
In this case, the fuel injection quantity for starting an engine is calculated by finding TILN with the basic fuel injection quantity Tl~NT~ time factor KLT' and rotational speed factor KLN according to the following equation:
T -- T X K X K
ILN ILNTIIK LT LN
It is preferable to set the second subtrahend to be applied to the time factor according to a period of time from an engine stalling in a first start to restarting.
In this case, the second subtrahend ~KLT2 to be applied to the time factor is calculated with a time period ~Tx from an engine stalling at a first start to restarting according to the following equation:
~KLT2 = (1/~TX) X K
where K is a matching value.
In this way, the second subtrahend to be applied to the time factor is set according to the period of time from an engine stalling in a first start to restarting, thereby optimizing the subtrahend and fuel injection quantity which will properly match a required fuel injection quantity.
The present invention will be explained in detail with reference to embodiments and drawings. The embodiments will help understand the invention more precisely. The invention, however, is not limited to the embodiments but freely modifiable within a scope of claims.
Brief Description of the Drawings Fig. 1 is a functional block diagram showing an arrangement of the invention;
Fig. 2 is a system diagram showing an embodiment of the invention;
Fig. 3 is a flowchart showing fuel injection quantity control processes for starting an engine;
Fig. 4 is characteristic diagrams showing basic fuel injection quantities for starting an engine, rotational speed factors, and time factors;
Fig. 5 is a flowchart showing time factor setting processes;
Fig. 6 is a time chart explaining effect of the time factor setting processes (this Figure appears on the second drawings page);
Fig. 7 is a time chart explaining time factor setting control according to another embodiment (this Figure appears on the second drawings page);
Fig. 8 is a flowchart showing the time factor setting processes according to the another embodiment;
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Fig. 9 is a characteristic diagram showing a time factor setting technique according to a prior art;
Fig. 10 is a time chart showing the time factor setting technique according to the prior art; and Fig. 11 is a time chart explaining the problem of the prior art.
Description of the Preferred Embodiments Figure 2 shows a control system of a two-cycle engine employing an electronically controlled fuel infection system according to an embodiment of the invention. Intake air passes an air cleaner (not shown), a throttle valve 12interlocked with an accelerator, and an intake manifold 13, and enters the engine 11.
The intake manifold 13 has a branch where a fuel injection valve 14 is arranged for each cylinder. The fuel injection valve 14 is a solenoid type fuel injection valve having a solenoid. When the solenoid is energized, the valve opens, and when it is de-energized, the valve closes. A control unit 15 provides the solenoid with a driving pulse signal to open the valve. While the valve is open, fuel which is pressurized by a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator is injected into the engine 11.
The control unit 15 receives output signals from various sensors serving as engine operation detecting means, processes the input data with a built-in ~ic~uco~p-Jter, determines a fuel injection quantity (an injection time) Ti as well as injection timing, and provides the valve 14 with the driving pulse signal. The control unit 15 provides an ignition device 22 with an operation control signal to control ignition timing. The microcomputer involves a central pluces~ing unit, an input/output processor, memories, etc.
The sensors include an ignition switch 21 serving as a start detecting means for detecting an engine start according to cranking operation of the engine. An output signal of the ignition switch 21 is received by the control unit 15. According to the output signal of the ignition switch 21, a timer incorporated in the control unit 15 detects a cranking time, i.e., a period of time during which the ignition switch is at a start position.
The sensors also include an airflow meter 16, which provides a signal representing an intake airflow rate Q. A distributor (not shown) incorporates an engine crank angle sensor 17 for outputting a reference signal every 120 degrees. By measuring a period of the reference signal, an engine speed can be detected.
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The throttle valve 12 has a throttle sensor 18 of potentiometer type for outputting a signal representing an aperture c~. The engine 11 has a water jacket having a water temperature sensor 19. The sensor 19 serves as an engine temperature detecting means and outputs a signal representing a cooling water temperature Tw. The control unit 15 receives a voltage from a power source battery 20 and detects a power source voltage VB.
Fuel injection control for starting an engine carried out by the microcomputer of the control unit 15 will be explained with reference to a flowchart of Fig. 3.
In Step 1 (indicated as S1 in the figure), the judging means of the control unit 15 judges whether or not it is an engine starting operation (whether or not the ignition switch is at the start position).
If it is the engine start, the flow proceeds to Step 2 in which the water temperature sensor 19 detects a cooling water temperature Tw as an engine temperature, and according to the detected temperature, a retrieving means of the control unit 15 retrieves a basic fuel injection quantity TILNTwK stored in advance in a ROM as shown in Fig. 4A.
Step 3 finds an engine speed N, and according to which, the retrieving means of the control unit 15 retrieves a rotational speed factor KLN stored in advance in the ROM as shown in Fig. 4B.
Step 4 finds a time factor KLT according to a table map of time factors KLT stored in advance in the ROM according to a cranking time T as shown in Fig. 4C, and a subtrahend provided by a subtrahend setting means to be explained later.
Step 5 calculates a fuel injection pulse width TILN according to the above-mentioned equation and controls the fuel injection valve 14 according to the calculated pulse width.
If it is not the engine starting operation, the flow advances from Step 1 to Step 6 to normally control Ti.
The control unit 15 incorporates, as software, a time factor setting means for updating and setting, at predetermined intervals, a time factor to be suitable for a cranking time by subtracting a predetermined subtrahend from a last time factor; a first subtrahend setting means for setting a first subtrahend to be applied to the time factor; a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor; a start judging means for judging, when the engine 11 is started, whether it is a first engine start or a second or later one; and a ~ ~3~
selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the secondsubtrahend setting means when the start judging meas provides a signal indicating the second or later engine start.
Operations of these means will be explained with reference to a time factor setting routine of Fig. 5.
Step 11 judges whether or not the engine 11 is started for the second time or afterward by judging whether or not the engine 11 is in a complete combustion state. This step judges whether or not a rotational speed of the engine 11 has once exceeded a set rotational speed before starting the engine 11.
If the speed of the engine 11 has once exceeded the set speed, it is judged to be a second or later engine starting operation to execute Step 12, which sets a flag (F) to 1 and proceeds to Step 13. If the speed of the engine 11 has not exceeded the set rotational speed, it is judged to be a first engine starting operation, and the flow directly proceeds to Step 13.
Step 13 judges whether or not the engine is in a stalled state (the engine is not operating). If the engine is in the stalled state, Step 14 sets the time factor KLT to an initial value 1, and proceeds to Step 15, which judges whether or not the flag (F) is 1. If the flag (F) is not 1, the flow proceeds to Step 16. Step 16 selects a first subtrahend AKLT1 as a subtrahend ~KLT to be applied to the time factor and goes to RETURN. If the flag (F) is 1, Step 17 selects a second subtrahend ~KLT2 which is larger than the first subtrahend ~KLT1~ as the subtrahend ~KLT to be applied to the time factor and goes to RETURN.
If Step 13 judges that the engine is operating, Step 18 successively updates and sets KLT according to the time factor KLT read out of the table map of time factors KLT stored in advance in the ROM as shown in Fig. 4C, and according to the first subtrahend AKLT1 or the second subtrahend AKLT2.
Namely, at a predetermined interval of time (for example, 65 ms), the subtrahend ~LT (~KLT1 or ~KLT2) is subtracted from a last value KLT (initially 1), thereby updating and setting KLT.
Namely, KLT= KLT-~KLTis calculated to successively update and set KLT. Thereafter, the process goes to RETURN.
In Fig. 3, Step 2 corresponds to the basic injection quantity setting means, Step 3 to the rotational speed factor setting means, Step 4 to the time factor setting means, and Step 5 to the initial injection quantity calculating means. In Fig. 5, Step 11 corresponds to the start judging means, Step 15 to the selecting means, Step 16 to the first subtrahend setting meas, Step 17 to the second subtrahend setting means, and Step 18 to the time factor setting means.
For starting the engine 11, the above arrangement has the two subtrahend setting means for setting a subtrahend to be applied to a time factor for correcting a basic fuel injection quantity according to a cranking time.
To restart the engine, the embodiment selects one of the subtrahend setting means which provides a larger subtrahend than the other which is used for starting the engine for the first time. According to the basic fuel injection quantity and a time factor to be set according to the selected subtrahend, an actual fuel injection quantity for restarting the engine is calculated.
In this way, the two subtrahend setting means are provided. To restart the engine, the subtrahend setting means which provides the larger subtrahend than the other used for a first engine starting operation is employed to correct the basic fuel injection quantity. If the engine 11 stalls due to a certain reason after it started and reached a complete combustion state, the engine must be restarted. In this case, an actual fuel injection quantity will never exceed a required fuel injection quantity of the engine, andan air-fuel ratio will never be too dense.
As a result, the restarting operation can surely drive the engine as shown in Fig. 6, thereby improving starting performance.
The above embodiment finds the fuel injection quantity for starting the engine by correcting the basic fuel injection quantity with the time factor as well as with the rotational speed factor which is set by the rotational speed factor setting means according to a cranking speed. The fuel injection quantity for starting the engine may be calculated by finding TlLN with the basic fuel injection quantity TILNTwK and time factor KLT according to the following equation:
TILN = TlLNTwK x KLT
Another embodiment of the invention will be explained.
This embodiment determines a second subtrahend ~KLT2 according to a period of time from an engine stalling in a first engine starting operation torestarting, i.e., an engine stall period ~Tx.
In this case, the second subtrahend ~KLT2 corresponding to the time period from an engine stalling in a first engine starting operation to restarting ~, ~G
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(the engine stall period) ~TX shown in Fig. 7 is calculated according to the following equation:
~ KLT2 = (1/~TX) x K
where K is a matching value.
A routine of this embodiment for setting the time factor is shown in a flowchart of Fig. 8. Steps 21 to 26, and 30 of this el"Lodi",er,l correspond to Steps 11 to 16, and 18 of Fig. 5. Steps 25 and 28 are peculiar to this embodiment.
Step 25 judges whether or not the flag (F) is 1. If the flag (F) is not 1, Step 26 selects the first subtrahend ~KLT1 as the ~KLT. If the flag (F) is 1, Step 27 counts ~TX with a timer incorporated in the control unit 15, and Step 28 calculates ~KLT2 = (1/~TX) x K to set the second subtrahend ~KLT2 This embodiment increases the second subtrahend ~KLT2 when the engine stall period ~TX is short, and decreases the second subtrahend ~KLT2 when the engine stall period ~TX is long, thereby optimally adjusting the second subtrahend ~KLT2 according to the engine stall period ~Tx. This arrangement provides an optimum fuel injection quantity matching with a required fuel injection quantity, thereby securely restarting the engine.
The fuel injection quantity control system according to the embodiments of the invention is particularly applicable for starting two-cycle engines such as snowmobiles which are used in cold climate conditions. snowmobiles, etc.
will benefit greatly from such an invention by being able to operate safely and continuously on snowy road conditions.
Title of the Invention FUEL INJECTION QUANTITY CONTROL SYSTEM FOR
STARTING A TWO-CYCLE ENGINE
Background of the Invention (1 ) Field of the Invention The present invention relates to a system of controlling the fuel injection quantity for starting a two-cycle engine, and particularly to a fuel injection quantity control system which can effectively start a two-cycle engine such as a s"o..."~ 'e engine to be used in cold climate conditions. After a failure in starting the engine, the system optimizes a fuel injection quantity for securelyrestarting the engine.
(2) Description of the Related Art Two-cycle engines for motorcycles and sl1o..,l, bi'vsl particularly those used in cold climate conditions frequently employ a fuel supply system of electronically controlled fuel injection type using a fuel injection valve. (Refer to, for example, Japanese Unexamined Patent Publication No. 63-255543.) This sort of system provides the intake manifold of each cylinder with a fuel injection valve to simultaneously inject fuel to all cylinders.
The fuel injection quantity control system of electronically controlled fuel injection type sets a slightly larger fuel injection quantity in starting a two-cycle engine than in normally driving the engine, thereby easily starting the engine.
When an ignition switch is turned to a start position for cranking the engine, the system controls the fuel injection valve to inject fuel in a quantity (a fuel injection pulse width) expressed with the following equation:
TILN = TlLNTwK x KLN x KLT
where TILN is a fuel injection pulse width for starting the engine, TILNTwK a basic fuel injection quantity for starting the engine, KLN a rotational speed factor, and KLT a time factor.
The basic fuel injection quantity TILNTwK which differs depending on engine temperature is stored in advance in a memory. The rotational speed factor KLN changes depending on cranking speed. The time factor KLT
changes depending on cranking time.
As shown in Fig. 9, the time factor KLT is updated at a predetermined interval of time (for example, 65 ms) by subtracting a predetermined value LT from a last time factor KLT (1 at first).
Namely, the time factor KLT is successively updated accor~ing to KLT =
KLT - ~KLT and decl~asecl according to elapsing time as shown in Fig. 10.
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Figure 11 shows the problem of the above-mentioned fuel injection quantity control system for starting a two-cycle engine. In the figure, the engine was started and once driven to a complete combustion state.
Thereafter, due to a certain reason, a speed N of the engine dropped, and the engine stalled. The engine was then restarted. In cold conditions, however, the engine speed N hardly rose to fail restarting.
The reason of this failure is because the time factor KLT is newly set for every starting operation, thereby setting a large time factor in correcting a fuel injection quantity for restarting the engine. As a result, excessive fuel is injected to the engine. Namely, the actual fuel injection quantity exceeds the required fuel injection quantity of the engine, thereby setting an air-fuel ratio to be too dense.
Summary of the Invention In view of the problem of the conventional system, an object of the invention is to securely restart an engine after a failure in starting the engine by optimizing a correction factor of the fuel injection quantity according to cranking time in such a way that the actual fuel injection quantity may not exceed the required fuel injection quantity of the engine, and that an air-fuel ratio may not be too dense.
To achieve the object, the invention provides, as shown in Fig. 1, a fuel injection quantity control system for starting a two-cycle engine, comprising:
a fuel injection valve;
an engine operation detecting means including a start detecting means for detecting the start of the engine according to the cranking operation of theengine, a cranking time detecting means for detecting cranking time, and an engine temperature detecting means for detecting the engine temperature;
a basic injection quantity setting means for setting the basic fuel injection quantity for starting the engine according to the engine temperature;
a time factor setting means for updating and setting, at predetermined intervals, a time factor to be suitable for the cranking time by subtracting a predetermined subtrahend from a last time factor;
a first subtrahend setting means for setting a first subtrahend to be applied to the time factor;
a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor;
a start judging means for judging, when an engine start is detected, whether it is a first engine start, or a second or later one;
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a selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the second subtrahend setting means when the start judging means provides a signal indicating the second or later engine start; and an initial injection quantity calculating means for calculating an initial fuel injection quantity according to the basic injection quantity provided by the basic injection quantity setting means and a time factor prepared in the time factor setting means, the time factor setting means preparing the time factor according to a subtrahend which is provided by the selected one of the subtrahend setting means.
In this way, the present invention employs two subtrahend setting means for setting a subtrahend to be applied to a time factor for correcting thebasic fuel injection quantity according to a cranking time. In restarting the engine, the invention selects one of the subtrahend setting means which provides a larger subtrahend than the other which is used for starting the engine for the first time. Based on the basic fuel injection quantity and the time factor determined according to the subtrahend, the invention calculates a fuel injection quantity for restarting the engine.
As mentioned above, the invention employs two subtrahend setting means. To restart the engine, the invention corrects the basic fuel injection quantity according to a subtrahend provided by one of the subtrahend setting means which is larger than that provided by the other which is used for a first engine starting operation. Even if the engine stalls due to a certain reason after it started and reached a complete combustion state, the invention can restart the engine with an actual fuel injection quantity not exceeding a required fuel injection quantity and with an air-fuel ratio being not too dense. As a result, the invention can surely restart the engine, thereby improving starting performance.
A fuel injection quantity for starting an engine is calculated by finding TILN with a basic fuel injection quantity TILNTwK and a time factor KLT
according to the following equation:
TILN = TlLNTwK x KLT
The fuel injection quantity may be calculated not only by correcting the basic fuel injection quantity TILNTwK with the time factor KLT but also by correcting the basic fuel injection quantity with a rotational speed factor KLN
set by a rotational speed factor setting means according to a cranking speed.
In this case, the fuel injection quantity for starting an engine is calculated by finding TILN with the basic fuel injection quantity Tl~NT~ time factor KLT' and rotational speed factor KLN according to the following equation:
T -- T X K X K
ILN ILNTIIK LT LN
It is preferable to set the second subtrahend to be applied to the time factor according to a period of time from an engine stalling in a first start to restarting.
In this case, the second subtrahend ~KLT2 to be applied to the time factor is calculated with a time period ~Tx from an engine stalling at a first start to restarting according to the following equation:
~KLT2 = (1/~TX) X K
where K is a matching value.
In this way, the second subtrahend to be applied to the time factor is set according to the period of time from an engine stalling in a first start to restarting, thereby optimizing the subtrahend and fuel injection quantity which will properly match a required fuel injection quantity.
The present invention will be explained in detail with reference to embodiments and drawings. The embodiments will help understand the invention more precisely. The invention, however, is not limited to the embodiments but freely modifiable within a scope of claims.
Brief Description of the Drawings Fig. 1 is a functional block diagram showing an arrangement of the invention;
Fig. 2 is a system diagram showing an embodiment of the invention;
Fig. 3 is a flowchart showing fuel injection quantity control processes for starting an engine;
Fig. 4 is characteristic diagrams showing basic fuel injection quantities for starting an engine, rotational speed factors, and time factors;
Fig. 5 is a flowchart showing time factor setting processes;
Fig. 6 is a time chart explaining effect of the time factor setting processes (this Figure appears on the second drawings page);
Fig. 7 is a time chart explaining time factor setting control according to another embodiment (this Figure appears on the second drawings page);
Fig. 8 is a flowchart showing the time factor setting processes according to the another embodiment;
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Fig. 9 is a characteristic diagram showing a time factor setting technique according to a prior art;
Fig. 10 is a time chart showing the time factor setting technique according to the prior art; and Fig. 11 is a time chart explaining the problem of the prior art.
Description of the Preferred Embodiments Figure 2 shows a control system of a two-cycle engine employing an electronically controlled fuel infection system according to an embodiment of the invention. Intake air passes an air cleaner (not shown), a throttle valve 12interlocked with an accelerator, and an intake manifold 13, and enters the engine 11.
The intake manifold 13 has a branch where a fuel injection valve 14 is arranged for each cylinder. The fuel injection valve 14 is a solenoid type fuel injection valve having a solenoid. When the solenoid is energized, the valve opens, and when it is de-energized, the valve closes. A control unit 15 provides the solenoid with a driving pulse signal to open the valve. While the valve is open, fuel which is pressurized by a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator is injected into the engine 11.
The control unit 15 receives output signals from various sensors serving as engine operation detecting means, processes the input data with a built-in ~ic~uco~p-Jter, determines a fuel injection quantity (an injection time) Ti as well as injection timing, and provides the valve 14 with the driving pulse signal. The control unit 15 provides an ignition device 22 with an operation control signal to control ignition timing. The microcomputer involves a central pluces~ing unit, an input/output processor, memories, etc.
The sensors include an ignition switch 21 serving as a start detecting means for detecting an engine start according to cranking operation of the engine. An output signal of the ignition switch 21 is received by the control unit 15. According to the output signal of the ignition switch 21, a timer incorporated in the control unit 15 detects a cranking time, i.e., a period of time during which the ignition switch is at a start position.
The sensors also include an airflow meter 16, which provides a signal representing an intake airflow rate Q. A distributor (not shown) incorporates an engine crank angle sensor 17 for outputting a reference signal every 120 degrees. By measuring a period of the reference signal, an engine speed can be detected.
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The throttle valve 12 has a throttle sensor 18 of potentiometer type for outputting a signal representing an aperture c~. The engine 11 has a water jacket having a water temperature sensor 19. The sensor 19 serves as an engine temperature detecting means and outputs a signal representing a cooling water temperature Tw. The control unit 15 receives a voltage from a power source battery 20 and detects a power source voltage VB.
Fuel injection control for starting an engine carried out by the microcomputer of the control unit 15 will be explained with reference to a flowchart of Fig. 3.
In Step 1 (indicated as S1 in the figure), the judging means of the control unit 15 judges whether or not it is an engine starting operation (whether or not the ignition switch is at the start position).
If it is the engine start, the flow proceeds to Step 2 in which the water temperature sensor 19 detects a cooling water temperature Tw as an engine temperature, and according to the detected temperature, a retrieving means of the control unit 15 retrieves a basic fuel injection quantity TILNTwK stored in advance in a ROM as shown in Fig. 4A.
Step 3 finds an engine speed N, and according to which, the retrieving means of the control unit 15 retrieves a rotational speed factor KLN stored in advance in the ROM as shown in Fig. 4B.
Step 4 finds a time factor KLT according to a table map of time factors KLT stored in advance in the ROM according to a cranking time T as shown in Fig. 4C, and a subtrahend provided by a subtrahend setting means to be explained later.
Step 5 calculates a fuel injection pulse width TILN according to the above-mentioned equation and controls the fuel injection valve 14 according to the calculated pulse width.
If it is not the engine starting operation, the flow advances from Step 1 to Step 6 to normally control Ti.
The control unit 15 incorporates, as software, a time factor setting means for updating and setting, at predetermined intervals, a time factor to be suitable for a cranking time by subtracting a predetermined subtrahend from a last time factor; a first subtrahend setting means for setting a first subtrahend to be applied to the time factor; a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor; a start judging means for judging, when the engine 11 is started, whether it is a first engine start or a second or later one; and a ~ ~3~
selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the secondsubtrahend setting means when the start judging meas provides a signal indicating the second or later engine start.
Operations of these means will be explained with reference to a time factor setting routine of Fig. 5.
Step 11 judges whether or not the engine 11 is started for the second time or afterward by judging whether or not the engine 11 is in a complete combustion state. This step judges whether or not a rotational speed of the engine 11 has once exceeded a set rotational speed before starting the engine 11.
If the speed of the engine 11 has once exceeded the set speed, it is judged to be a second or later engine starting operation to execute Step 12, which sets a flag (F) to 1 and proceeds to Step 13. If the speed of the engine 11 has not exceeded the set rotational speed, it is judged to be a first engine starting operation, and the flow directly proceeds to Step 13.
Step 13 judges whether or not the engine is in a stalled state (the engine is not operating). If the engine is in the stalled state, Step 14 sets the time factor KLT to an initial value 1, and proceeds to Step 15, which judges whether or not the flag (F) is 1. If the flag (F) is not 1, the flow proceeds to Step 16. Step 16 selects a first subtrahend AKLT1 as a subtrahend ~KLT to be applied to the time factor and goes to RETURN. If the flag (F) is 1, Step 17 selects a second subtrahend ~KLT2 which is larger than the first subtrahend ~KLT1~ as the subtrahend ~KLT to be applied to the time factor and goes to RETURN.
If Step 13 judges that the engine is operating, Step 18 successively updates and sets KLT according to the time factor KLT read out of the table map of time factors KLT stored in advance in the ROM as shown in Fig. 4C, and according to the first subtrahend AKLT1 or the second subtrahend AKLT2.
Namely, at a predetermined interval of time (for example, 65 ms), the subtrahend ~LT (~KLT1 or ~KLT2) is subtracted from a last value KLT (initially 1), thereby updating and setting KLT.
Namely, KLT= KLT-~KLTis calculated to successively update and set KLT. Thereafter, the process goes to RETURN.
In Fig. 3, Step 2 corresponds to the basic injection quantity setting means, Step 3 to the rotational speed factor setting means, Step 4 to the time factor setting means, and Step 5 to the initial injection quantity calculating means. In Fig. 5, Step 11 corresponds to the start judging means, Step 15 to the selecting means, Step 16 to the first subtrahend setting meas, Step 17 to the second subtrahend setting means, and Step 18 to the time factor setting means.
For starting the engine 11, the above arrangement has the two subtrahend setting means for setting a subtrahend to be applied to a time factor for correcting a basic fuel injection quantity according to a cranking time.
To restart the engine, the embodiment selects one of the subtrahend setting means which provides a larger subtrahend than the other which is used for starting the engine for the first time. According to the basic fuel injection quantity and a time factor to be set according to the selected subtrahend, an actual fuel injection quantity for restarting the engine is calculated.
In this way, the two subtrahend setting means are provided. To restart the engine, the subtrahend setting means which provides the larger subtrahend than the other used for a first engine starting operation is employed to correct the basic fuel injection quantity. If the engine 11 stalls due to a certain reason after it started and reached a complete combustion state, the engine must be restarted. In this case, an actual fuel injection quantity will never exceed a required fuel injection quantity of the engine, andan air-fuel ratio will never be too dense.
As a result, the restarting operation can surely drive the engine as shown in Fig. 6, thereby improving starting performance.
The above embodiment finds the fuel injection quantity for starting the engine by correcting the basic fuel injection quantity with the time factor as well as with the rotational speed factor which is set by the rotational speed factor setting means according to a cranking speed. The fuel injection quantity for starting the engine may be calculated by finding TlLN with the basic fuel injection quantity TILNTwK and time factor KLT according to the following equation:
TILN = TlLNTwK x KLT
Another embodiment of the invention will be explained.
This embodiment determines a second subtrahend ~KLT2 according to a period of time from an engine stalling in a first engine starting operation torestarting, i.e., an engine stall period ~Tx.
In this case, the second subtrahend ~KLT2 corresponding to the time period from an engine stalling in a first engine starting operation to restarting ~, ~G
~ 8 2~31.~
(the engine stall period) ~TX shown in Fig. 7 is calculated according to the following equation:
~ KLT2 = (1/~TX) x K
where K is a matching value.
A routine of this embodiment for setting the time factor is shown in a flowchart of Fig. 8. Steps 21 to 26, and 30 of this el"Lodi",er,l correspond to Steps 11 to 16, and 18 of Fig. 5. Steps 25 and 28 are peculiar to this embodiment.
Step 25 judges whether or not the flag (F) is 1. If the flag (F) is not 1, Step 26 selects the first subtrahend ~KLT1 as the ~KLT. If the flag (F) is 1, Step 27 counts ~TX with a timer incorporated in the control unit 15, and Step 28 calculates ~KLT2 = (1/~TX) x K to set the second subtrahend ~KLT2 This embodiment increases the second subtrahend ~KLT2 when the engine stall period ~TX is short, and decreases the second subtrahend ~KLT2 when the engine stall period ~TX is long, thereby optimally adjusting the second subtrahend ~KLT2 according to the engine stall period ~Tx. This arrangement provides an optimum fuel injection quantity matching with a required fuel injection quantity, thereby securely restarting the engine.
The fuel injection quantity control system according to the embodiments of the invention is particularly applicable for starting two-cycle engines such as snowmobiles which are used in cold climate conditions. snowmobiles, etc.
will benefit greatly from such an invention by being able to operate safely and continuously on snowy road conditions.
Claims (6)
1. A fuel injection quantity control system for starting a two-cycle engine, comprising:
a fuel injection valve;
an engine operation detecting means including a start detecting means for detecting a start of the engine according to cranking operation of the engine, a cranking time detecting means for detecting cranking time, and an engine temperature detecting means for detecting the engine temperature;
a basic injection quantity setting means for setting a basic fuel injection quantity for starting the engine according to the engine temperature;
a time factor setting means for updating and setting, at predetermined intervals, a time factor suitable to the cranking time by subtracting a predetermined subtrahend from a last time factor;
a first subtrahend setting means for setting a first subtrahend to be applied to the time factor;
a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor;
a start judging means for judging, when an engine start is detected, whether it is a first engine start, or a second or later one;
a selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the second subtrahend setting means when the start judging means provides a signal - Page 1 of Claims -indicating the second or later engine start; and an initial injection quantity calculating means for calculating an initial fuel injection quantity according to the basic injection quantity provided by the basic injection quantity setting means and the time factor prepared in the time factor setting means, the time factor setting means preparing the time factor according to a subtrahend which is provided by one of the subtrahend setting means.
a fuel injection valve;
an engine operation detecting means including a start detecting means for detecting a start of the engine according to cranking operation of the engine, a cranking time detecting means for detecting cranking time, and an engine temperature detecting means for detecting the engine temperature;
a basic injection quantity setting means for setting a basic fuel injection quantity for starting the engine according to the engine temperature;
a time factor setting means for updating and setting, at predetermined intervals, a time factor suitable to the cranking time by subtracting a predetermined subtrahend from a last time factor;
a first subtrahend setting means for setting a first subtrahend to be applied to the time factor;
a second subtrahend setting means for setting a second subtrahend which is larger than the first subtrahend and to be applied to the time factor;
a start judging means for judging, when an engine start is detected, whether it is a first engine start, or a second or later one;
a selecting means for selecting the first subtrahend setting means when the start judging means provides a signal indicating the first engine start, or the second subtrahend setting means when the start judging means provides a signal - Page 1 of Claims -indicating the second or later engine start; and an initial injection quantity calculating means for calculating an initial fuel injection quantity according to the basic injection quantity provided by the basic injection quantity setting means and the time factor prepared in the time factor setting means, the time factor setting means preparing the time factor according to a subtrahend which is provided by one of the subtrahend setting means.
2. A fuel injection quantity control system for starting a two-cycle engine as set forth in claim 1, wherein the initial injection quantity calculating means calculates an initial injection quantity TILN with a basic injection quantity TILNTWK
and a time factor KLT according to the following equation:
TILN = TILNTWK X KLT.
and a time factor KLT according to the following equation:
TILN = TILNTWK X KLT.
3. A fuel injection quantity control system for starting a two-cycle engine as set forth in claim 1, further comprising a rotational speed factor setting means for setting a rotational speed factor according to a cranking speed, wherein the initial injection quantity calculating means calculates an initial injection quantity according to the basic injection quantity provided by the basic injection quantity setting means, the time factor provided by the time factor setting means, and the rotational speed factor provided by the rotational speed factor setting means.
4. A fuel injection quantity control system for starting a two-cycle engine as set forth in claim 1, wherein the initial injection quantity calculating means calculates an initial injection quantity TILN with a basic injection quantity TILNTWK' - Page 2 of Claims -a time factor KLT, and a rotational speed factor KLN according to the following equation:
TILN = TILNTWK X KLT X KLN.
TILN = TILNTWK X KLT X KLN.
5. A fuel injection quantity control system for starting a two-cycle engine as set forth in claim 1, wherein the second subtrahend setting means sets a second subtrahend according to a period of time from a first engine start to restarting.
6. A fuel injection quantity control system for starting two-cycle engine as set forth in claim 5, wherein the second subtrahend setting means sets a second subtrahend .DELTA.KLT2 according to a period of time .DELTA.Tx from an engine stalling in a first engine starting to restarting according to the following equation:
.DELTA. KLT2 = (1/.DELTA.TX) X K
where K is a matching value.
- Page 3 of Claims -
.DELTA. KLT2 = (1/.DELTA.TX) X K
where K is a matching value.
- Page 3 of Claims -
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2043195 CA2043195C (en) | 1991-05-24 | 1991-05-24 | Fuel injection quantity control system for starting a two-cycle engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2043195 CA2043195C (en) | 1991-05-24 | 1991-05-24 | Fuel injection quantity control system for starting a two-cycle engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2043195A1 CA2043195A1 (en) | 1992-11-25 |
| CA2043195C true CA2043195C (en) | 1998-06-30 |
Family
ID=4147651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2043195 Expired - Fee Related CA2043195C (en) | 1991-05-24 | 1991-05-24 | Fuel injection quantity control system for starting a two-cycle engine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2043195C (en) |
-
1991
- 1991-05-24 CA CA 2043195 patent/CA2043195C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2043195A1 (en) | 1992-11-25 |
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