EP2299095B1

EP2299095B1 - Engine control system for a vehicle

Info

Publication number: EP2299095B1
Application number: EP10173319.4A
Authority: EP
Inventors: Norimasa Yamamoto
Original assignee: Kawasaki Heavy Industries Ltd; Kawasaki Jukogyo KK
Current assignee: Kawasaki Heavy Industries Ltd; Kawasaki Motors Ltd
Priority date: 2009-08-24
Filing date: 2010-08-18
Publication date: 2019-06-26
Anticipated expiration: 2030-08-18
Also published as: JP5386273B2; EP2299095A2; EP2299095A3; JP2011043141A

Description

TECHNICAL FIELD

The present invention relates to an engine control system for a vehicle which is configured to control an engine, using a plurality of control modes.

DESCRIPTION OF THE RELATED ART

An exemplary engine control system built into a vehicle such as a motorcycle is configured to set one control mode selected from among a plurality of control modes such as a high driving power mode for providing a high acceleration capability, an economy mode for achieving a high fuel efficiency, and a normal mode, and control the engine using the set control mode. Japanese Laid-Open Patent Application Publication No. 2005-023991 discloses an engine control system configured to freely switch a control mode by a driver's operation of a mode select switch coupled to the input of the engine control system.
An engine control system is configured to obtain command values such as an ignition timing and a fuel injection amount according to input values indicating driving states such as accelerator opening degree and an engine speed, and control the engine according to the command values. The command values derived from the input values are varied depending on the control mode. A conventional engine control system is configured to switch a control mode in response to the operation of the mode select switch regardless of the driving state. This will increase a chance that a driving state fluctuation increases, for example, the operation and output of the engine fluctuate, because of the switching of the control mode, depending on the driving state, which makes driving feel worse.
US 7,523,737 B2 , which forms the basis for the preamble of claim 1, discloses a motorcycle with a drive mode selecting switch which is operable to select an intended drive mode from a plurality of drive modes so as to select a sub-throttle valve opening degree map out of a plurality of stored sub-throttle valve opening degree maps. An engine control is operable to control an engine based on the selected sub-throttle valve opening degree map.
US 7,487,033 B2 discloses an engine control apparatus in which a power mode is set based on a position of a mode select switch.

SUMMARY OF THE INVENTION

The present invention has been developed in view of the circumstances, and an object of the present invention is to improve diving feel of a driver driving a vehicle including an engine control system configured to control an engine using a plurality of control modes.
According to a first aspect of the present invention, an engine control system for a vehicle is presented according to claim 1, which is configured to control an engine using a plurality of control modes, comprising: a controller configured to selectively set a first control mode or a second control mode and to control the engine using the set control mode, the engine being operable with a smaller fuel amount in the second control mode than in the first control mode; and a mode switching device for switching the control mode set in the controller between the first control mode and the second control mode, wherein the mode switching device includes an operation member which is operated by a driver, wherein the controller is configured to determine that the command for switching the control mode has been input only when an operation time for which the operation member is operated by the driver falls within a predetermined time range which is not less than a predetermined first time and not more than a predetermined second time; wherein the controller is configured to determine that a command for switching the control mode is valid if a predetermined driving condition is met, in response to the command input to the mode switching device, and to determine that the command is invalid if the predetermined driving condition is not met, in response to the command input to the mode switching device. The engine control system is characterized in that the engine controller comprises an acceleration determiner configured to determine whether or not the vehicle is driving with a predetermined acceleration, a driving power transmission determiner configured to determine whether or not a transmission path of a driving power generated in the engine is disconnected, and a gear position sensor for detecting a gear position of a transmission mounted in the vehicle;, in that the predetermined driving condition includes a first condition that the vehicle is driving with an acceleration less than the predetermined acceleration, and a second condition that the transmission path is disconnected or the gear position detected by the gear position sensor is a gear position corresponding to a reduction gear ratio less than a predetermined reduction gear ratio which is not more than a maximum reduction gear ratio; and in that the predetermined driving condition is met when the first condition and the second condition are met.
In accordance with the above configuration, the control mode is not switched when the predetermined driving condition is not met, and therefore, a driving state fluctuation due to the switching of the control mode is suppressed. This makes it possible to maintain good driving feel.
In a case where the vehicle is accelerated, the switching of the control mode is inhibited to prevent fluctuation of the operation and output of the engine and fluctuation the vehicle speed, which would occur if the control mode is switched. As a result, the driving state fluctuation due to the switching of the control mode can be suppressed.
As mentioned above, the presented engine control system for the vehicle comprises a driving power transmission determiner configured to determine whether or not a transmission path of a driving power generated in the engine is disconnected; and the predetermined driving condition includes a condition that the transmission path is disconnected.
In accordance with this configuration, even when the operation and output of the engine change due to the switching of the control mode, in the state where the driving power transmission path is disconnected, this change is less likely to bring about the driving state fluctuation. Therefore, in this case, the switching of the control mode is permitted and as a result, the control mode can be switched without worsening driving feel.
As mentioned above, the presented engine control system for the vehicle comprises a gear position sensor for detecting a gear position of a transmission mounted in the vehicle; and the predetermined driving condition includes a condition that the gear position detected by the gear position sensor is a gear position corresponding to a reduction gear ratio less than a predetermined reduction gear ratio which is not more than a maximum reduction gear ratio.
In accordance with this configuration, the switching of the control mode is inhibited when the reduction gear ratio is not a reduction gear ratio which is less than a predetermined reduction gear ratio which is not more than the maximum reduction gear ratio, i.e., a transmission gear which is lower than a certain transmission gear is set in the transmission. The lower transmission gear is set in a driving state where a vehicle speed tends to change significantly in a state where acceleration is required, during, for example, starting of the vehicle, or a state where a relatively large engine braking force is applied to decelerate the vehicle. In this case, the switching of the control mode is inhibited, and as a result, the driving state fluctuation due to the switching of the control mode can be suppressed.
The engine control system for the vehicle may further comprise a vehicle speed sensor for detecting a vehicle speed; and the predetermined driving condition may include a third condition that the vehicle speed detected by the vehicle speed sensor falls within a predetermined speed range which is not less than a predetermined first speed and not more than a predetermined second speed. The predetermined driving condition is met when the first condition, the second condition, and the third condition are met. The predetermined first speed may be higher than zero and the second predetermined speed may be set to a value larger than a value of the predetermined first speed.
In accordance with such a configuration, the switching of the control mode is inhibited in a case where the vehicle speed is in a low speed range which is less than the first speed and acceleration is required to start the motorcycle. Therefore, the speed fluctuation or the driving state fluctuation due to the switching of the control mode can be suppressed. In addition, the switching of the control mode is inhibited in a case where the vehicle speed is in a high speed range which is more than the second speed and there is not a substantial difference in the operation command values for the engine, such as a fuel injection amount, or the like, regardless of the control mode. As a result, an unnecessary switching operation of the control mode can be prevented.
As mentioned above, the presented mode switching device includes an operation member which is operated by a driver; and the controller is configured to determine that the command for switching the control mode has been input only when an operation time for which the operation member is operated by the driver falls within a predetermined time range which is not less than a predetermined first time and not more than a predetermined second time.
This makes it possible to prevent the control mode from being switched inadvertently by the fact that something touches the mode select switch by mistake or continues to contact the mode select switch for a long time.
The engine control system for the vehicle may further comprise a sensor for outputting a detection value used to determine whether or not a predetermined driving condition is met; and an abnormality determiner configured to determine whether or not abnormality occurs in the sensor. The controller may be configured to restrict switching of the control mode when the abnormality determiner determines that the abnormality occurs in the sensor.
In accordance with such a configuration, the switching of the control mode is restricted in a case where abnormality occurs in the sensor and it is difficult to correctly determine whether or not the driving condition is met. This reduces a chance of misdetermination that the driving condition is met, and hence an incorrect switching of the control mode.
The engine control system for the vehicle may further comprise a display device. The controller may be configured to cause the display device to conduct display in a different manner according to the set control mode.
The controller may be configured to set the first control mode at re-start of the engine if the command is not input to the mode switching device before the engine re-starts, and to set the second control mode at re-start of the engine when a command for switching the control mode to the second control mode is input to the mode switching device before the engine re-starts, when the engine is stopped in a state where the second control mode is set.
The above and further objects and features of the invention will more be apparent from the following detailed description with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a left side view of a motorcycle including an engine control system for a vehicle according to an embodiment of the present invention.
Fig. 2 is a schematic view showing a configuration of an engine and constituents in the vicinity of the engine of Fig. 1 and a configuration of an entire engine control system built into motorcycle of Fig. 1.
Fig. 3 is a block diagram of the engine control system, showing in a greater part, an electronic control unit of Fig. 2.
Fig. 4 is a flowchart showing a process for determining whether or not a driving condition is met, which is executed by a condition determiner of Fig. 3.
Fig. 5 is a flowchart showing an example useful for understanding the invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Hereinafter, a motorcycle will be described as an example of a vehicle, and the stated directions are referenced from the perspective of a driver driving the motorcycle, unless otherwise explicitly noted.
Fig. 1 is a left side view of a motorcycle 1 including an engine control system for a vehicle according to an embodiment of the present invention. Referring to Fig. 1, the motorcycle 1 includes a front wheel 2 and a rear wheel 3. The front wheel 2 is rotatably mounted to the lower end portion of a front fork 4 extending substantially vertically. The upper end portion of the front fork 4 is coupled to a handle 6 including a right and left grips via a steering shaft (not shown) rotatably supported by the head pipe 5. When the driver grips the grips and rotates the handle 6, the front wheel 2 rotates around the steering shaft. The grip gripped by the driver's right hand is a throttle grip 7 (see Fig. 2) which is rotated by twisting the driver's wrist to operate a throttle device 17. A clutch lever 8 is provided in front of the grip gripped by the driver's left hand.
A pair of right and left main frame members 9 extend rearward and downward from the head pipe 5. A pair of right and left pivot frame members 10 are coupled to the rear portions of the main frame members 9. The front end portions of swing arms 11 extending substantially in the longitudinal direction of the motorcycle 1 are coupled to the pivot frame members 10, respectively such that each swig arm 11 is pivotable around the front end portion. An engine 14 is mounted to the main frame members 9 and the pivot frame members 10. A driving power of the engine 14 is transmitted to the rear wheel 3 via a transmission 15 and a chain 16. The throttle device 17 is coupled to intake ports (not shown) of the engine 14, and an air cleaner 18 is coupled to the throttle device 17. A straddle seat 13 which is straddled by the driver is mounted behind the handle 6 such that a fuel tank 12 is interposed between them. An electronic control unit 19 (controller) is accommodated into an inner space below the seat 13 and is configured to control the operation of the engine 14.
Fig. 2 is a schematic view showing a configuration of the engine 14 and constituents in the vicinity of the engine 14 and a configuration of the entire engine control system 50 built into motorcycle 1 of Fig. 1. As shown in Fig. 2, the throttle device 17 includes an air-intake pipe 20 provided between the engine 14 and the air cleaner 18, a throttle valve 21 provided in an inner passage of the air-intake pipe 20, and a valve actuator 22 for driving the throttle valve 21. The throttle valve 21 is driven by the valve actuator 22 to open and close the inner passage of the air-intake pipe 20 such that its opening degree is variable, thereby controlling the amount of air fed to the engine 14. The engine 14 is provided with a fuel injection device 23 and an ignition device 24. The devices 23 and 24 operate at suitable timings so that ignition and combustion occur in cylinders, thereby allowing the engine 14 to generate a driving power.
The driving power of the engine 14 is transmitted to the rear wheel 3 via a driving power transmission path 25. As shown in Fig. 2, the driving power transmission path 25 includes an engine output shaft 26, a reduction gear mechanism 27, a clutch 28, a transmission input shaft 29, a transmission 15, a transmission output shaft 30, and a chain 16, in this order when viewed from the engine 14. The clutch 28 is coupled to a clutch lever 8 via a wire 8a. In a state where the clutch lever 8 is not operated, the clutch 28 is engaged to allow the driving power to be transmitted between the reduction gear mechanism 27 and the transmission input shaft 29, while in a state where the clutch lever 28 is operated, the clutch 28 is disengaged by the operation of the wire 8a not to permit the driving power to be transmitted between the reduction gear mechanism 27 and the transmission input shaft 29. The transmission 15 changes the speed of the rotation of the transmission input shaft 28 and transmits the resulting rotation to the transmission output shaft 30. The transmission 15 is, for example, a dog clutch type multi-stage transmission including a plurality of gear trains arranged in parallel. The transmission 15 is configured to select one from among a plurality of gears. The transmission gears include a plurality of forward transmission gears which are different in gear ratio and a neutral gear for inhibiting transmission of the driving power between the transmission input shaft 29 and the transmission output shaft 30. The transmission gear is set and changed by operating a shift pedal (not shown) to shift a gear position.
The electronic control unit 19 is configured to receive signals from sensors for detecting driving states as inputs and control the engine 14 and the associated devices in accordance with the detected driving states and the set control mode. The electronic control unit 19 is configured to selectively set one from among the plurality of control modes. In this embodiment, the control modes which can be set in the electronic control unit 19 includes two control modes which are a normal mode and an economy mode for allowing the engine 14 to operate with a smaller fuel amount than in the normal mode. The electronic control unit 19 is configured to turn ON and OFF the economy mode. To be specific, control maps corresponding to respective control modes are pre-stored in the electronic control unit 19, and the electronic control unit 19 is configured to obtain operation command values of the engine 14 and the associated devices with reference to these control maps. The control mode switches according to the switching of the control map to be referred to.
As shown in Fig. 2, sensors coupled to the inputs of the electronic control unit 19 include a grip position sensor 31 for detecting an operation position of the throttle grip 7, a throttle valve position sensor 32 (throttle valve opening degree sensor) for detecting an opening degree of the throttle valve 21, an engine speed sensor 33 for detecting an engine speed of the engine 14, a gear position sensor 34 for detecting a gear position of the transmission 15, a clutch operation switch 35 for detecting whether or not the clutch lever 8 has been operated, and a vehicle speed sensor 36 for detecting a vehicle speed of the motorcycle 1. The electronic control unit 19 is configured to detect a current gear set in the transmission 15 based on the signal received from the gear position sensor 34 and to detect whether or not the clutch 28 is disengaged based on the signal received from the clutch operation switch 35. The vehicle speed sensor 36 is configured to detect the rotational speed of the front wheel 2. The electronic control unit 19 is configured to execute predetermined calculation based on the detection value from the vehicle speed sensor 36 to measure the vehicle speed of the motorcycle 1. Alternatively, an acceleration sensor for detecting acceleration, and a neutral gear position sensor for detecting that a neutral gear is set in the transmission 15 may be communicatively coupled to the electronic control unit 19, although not shown.
Furthermore, a mode select switch 37 (mode switching device) is communicatively coupled to the input of the electronic control unit 19 to input a command for switching the control mode to the electronic control unit 19. The mode select switch 37 is positioned adjacent the grip of the handle 6 and easily operated by the driver during driving. The mode select switch 37 may be a press-button switch, a toggle switch, or a rocker switch, but the press-button switch is suitably used when the electronic control unit 19 performs the determination process using an input time determiner 41 (see Fig. 3) as described later.
As shown in Fig. 2, the components of the engine 14 which are coupled to the outputs of the electronic control unit 19 include the valve actuator 22 of the throttle device 17, the fuel injection device 23 and the ignition device 24.
A mode display device 38 is coupled to the output of the electronic control unit 19 to display a control mode currently set. The mode display device 38 is attached on an instrument panel (not shown) positioned in close proximity to the handle (see Fig. 1) and can be visually checked by the driver during driving. The mode display device 38 may be a suitable device such as a lamp, or a liquid crystal display.
An economy lamp 39 is coupled to the output of the electronic control unit 19 to display a state where the motorcycle 1 is driving under a fuel-efficient condition when a current driving state is the fuel-efficient condition. The electronic control unit 19 includes a fuel-efficient driving state determiner (not shown) configured to determine whether or not the motorcycle 1 is driving under a fuel-efficient condition. The fuel-efficient driving state determiner may be configured to determine whether or not the engine speed falls within a predetermined numeric range, whether or not a change amount of the engine speed falls within a predetermined range, whether or not the opening degree of the throttle valve 21 falls within a predetermined opening degree range, whether or not a change amount of the opening degree of the throttle valve 21 falls within a predetermined range, whether or not the vehicle speed is higher than zero, and whether or not the clutch lever 8 has been operated. If it is determined as "YES" in at least one of determination steps, the fuel-efficient driving state determiner detects that the motorcycle 1 is driving under the fuel-efficient condition and turns ON the economy lamp 39. The driver can easily check the ON or OFF of the economy lamp 39 provided on the instrument panel during driving, thereby facilitating the fuel-efficient driving. Alternatively, the upper limit values and the lower limit values defining the engine speed range and the opening degree range may be changed according to the gear set in the transmission 15.
As described above, the engine control system 50 of this embodiment includes the electronic control unit 19, the sensors 31 to 36 coupled to the inputs of the electronic control unit 19, the mode select switch 37 coupled to the input of the electronic control unit 19, the devices 22 to 24 of the engine 14 which are coupled to the outputs of the electronic control unit 19, the mode display device 38 coupled to the output of the electronic control unit 19, and the economy lamp 39 coupled to the output of the electronic control unit 19.
Fig. 3 is a block diagram of the engine control system 50, showing in a greater part, the electronic control unit 19 of Fig. 2. Referring to Fig. 3, the electronic control unit 19 is configured to determine whether a command for switching the control mode which has been input by the driver's operation of the mode select switch 37 is valid or invalid, and switch the control mode if it is determined that the command is valid. In accordance with the set control mode, the operations of the devices 22 to 24 and the operation of the mode display device 38 are controlled. For the control, the electronic control unit 19 includes a memory 40, the input time determiner 41, an abnormality determiner 42, a condition determiner 43, a mode setting section 44, a throttle controller 45, a fuel controller 46, and an ignition controller 47. Hereinafter, the command for switching the control mode is sometimes simply referred to as "command."
The control maps corresponding to the respective control modes are pre-stored in the memory 40. These control maps are referred to in order to obtain the operation amount of the valve actuator 22 corresponding to a target opening degree of the throttle valve 21, the operation time of the fuel injection device 23 corresponding to a target fuel amount of the fuel injected from the fuel injection device 23, and the operation timing of the ignition device 24 corresponding to a target igniting timing.
When the mode select switch 37 is operated and the command for switching the control mode is input to the electronic control unit 19, the input time determiner 41 determines whether or not the operation time (i.e., time period from the operation starts until the operation ends) falls within a range from a predetermined first time to a predetermined second time. If it is determined that the operation time falls within this range, the input time determiner 41 determines that the command has been input, whereas if it is determined that the operation time does not fall within this range, the input time determiner 41 determines that the command has not been input. In other words, the input time determiner 41 is configured to determine that the command has been input, only when the mode select switch 37 has been operated for a long time correctly. The predetermined first time is set to, for example, about one second and the predetermined second time is set to, for example, about three seconds. This makes it possible to prevent the control mode from being switched inadvertently by the fact that something touches the mode select switch 37 by mistake or continues to contact the mode select switch 37 for a long time. The electronic control unit 19 changes a display content in the instrument panel when the operation time falls within the range between the first time and the second time. This enables the driver to know that the operation time falls within this predetermined range. If the driver wishes to change the control mode, the driver must finish the operation of the mode select switch 37 while the display content is changing, thereby preventing the operation time from exceeding the second time.
The abnormality determiner 42 is configured to determine whether or not there is an abnormality such as disconnection of signal lines in the sensors 31 to 36 coupled to the inputs of the electronic control unit 19. Whether the input command is determined as valid or invalid may be determined based on whether or not a predetermined driving condition is met as described later. If there is an abnormality in the sensors 31 to 36, it is difficult to determine the driving condition correctly using the detection values of the sensors 31 to 36. From this, the condition determiner 43 is configured to determine whether the command is valid or invalid only when the abnormality determiner 42 determines that the sensors 31 to 36 are normal. If not, the switching of the control mode is inhibited even when the input time determiner 41 determines that the command has been input. This abnormality determination process is performed every time ignition is ON, i.e., a command for starting-up the motorcycle 1 is input. If the abnormality determiner 42 determines that there is an abnormality, this determination continues and the switching of the control mode is inhibited until ignition is OFF, when a command for stopping the motorcycle 1 is input. For example, if the abnormality of the sensors is obviated after the ignition is ON, the switching of the control mode continues to be inhibited. If it is determined that the sensors are normal when next ignition is ON, then the condition determiner 43 determines whether the command is valid or invalid.
The condition determiner 43 is configured to determine whether or not predetermined driving conditions are met based on signals from the sensors 31 to 36 coupled to the inputs of the electronic control unit 19, if the input time determiner 41 determines that the command has been input and the abnormality determiner 42 determines that the sensors 31 to 36 are normal. In this case, if the predetermined driving condition is met, the condition determiner 43 determines that the command is valid, whereas if the predetermined driving condition is not met, the condition determiner 43 determines that the command is invalid. The driving condition relates to the driving states of the vehicle at the time point when the mode switching command is input, and includes, at least one of, for example, a vehicle speed, an engine speed, a gear ratio, and a clutch state.
If the condition determiner 43 determines that the command is valid, the mode setting section 44 reads out a control map corresponding to the switched control mode, from the memory 40, whereas if the condition determiner 43 determines that the command is invalid, the mode setting section 43 keeps the current control map.
When the control map read out is the control map corresponding to the economy mode, the mode setting section 44 outputs a signal to the mode display device 38 to cause the mode display device 38 to display representing that the control mode is the economy mode. In a case the mode display device 38 is a lamp, for example, the mode setting section 44 outputs a signal for turning ON the lamp when the economy mode is set, while the mode setting section 44 outputs a signal for turning OFF the lamp when the normal mode is set. In this way, the mode setting section 44 causes the mode display device 38 to conduct display in a different manner according to the set control mode. The driver sees the mode display device 38 to know the control mode currently set. The driver can confirm that the command for switching the control mode is valid, after the driver has operated the mode select switch 37.
The throttle controller 45, the fuel controller 46 and the ignition controller 47 obtain the operation amount of the valve actuator 22, the operation time of the fuel injection device 23, and the ignition timing of the ignition device 24, respectively, based on the inputs received from the sensors 31 to 36 coupled to the inputs of the electronic control unit 19, with reference to the control map which has been read by the mode setting section 27. The throttle controller 45, the fuel controller 46 and the ignition controller 47 drive the valve actuator 22, the fuel injection device 23 and the ignition device 24, respectively, according to the obtained operation command values.
The control maps are designed according to the concepts of the control modes. Therefore, the operation command values are sometimes different, depending on the control maps, regardless of the same driving state, i.e., the same input. For example, when the motorcycle 1 is driving in the economy mode and an acceleration request is being made, a target fuel amount is set less or a change rate of the target fuel amount is set lower than in the normal mode, because the control map designed to restrain a fuel consumption amount is referred to in the economy mode. If the control mode is switched under this driving state, the operation and output of the engine 14 (see Fig. 2) may fluctuate and the driving state may fluctuate.
The condition determiner 43 is configured to determine that the predetermined driving condition is met if a substantial driving state fluctuation does not occur even when the control mode is switched, and permit the control mode from being switched when the predetermined driving condition is met. This makes it possible to suppress a driving state fluctuation and improve driving feel when the control mode is switched.
Fig. 4 is a flowchart showing a process for determining whether or not a driving condition is met, which is executed by the condition determiner 43 of Fig. 3. The determination process of Fig. 4 is carried out when the input time determiner 41 determines that the command has been input and abnormality determiner 42 determines that the sensors 31 to 35 are normal. Hereinafter, the reference characters will be referred to suitably with reference to Figs. 1 to 3 as well as Fig. 4.
Referring to Fig. 4, the condition determiner 43 determines whether or not the vehicle speed is 0 (step S1). If it is determined that the vehicle speed V is not 0 (S1: NO), the process goes to step S2. On the other hand, if it is determined that the vehicle speed V is 0 (S1: YES), the condition determiner 43 determines that the driving condition is met, and determines that the command is valid (step S10).
The condition determiner 43 determines whether or not the vehicle speed V falls within a speed range which is not less than a first vehicle speed V₁ larger than 0 and is less than a second vehicle speed V₂ higher than the first vehicle speed V₁ (step S2). If it is determined that the vehicle speed V falls within this speed range (S2: YES), the process goes to step S3. On the other hand, if it is determined that the vehicle speed V is outside this speed range (S2: NO), the condition determiner 43 determines that the driving condition is not met, and determines that the command is invalid (step S20).
The condition determiner 43 determines whether or not acceleration α of the motorcycle 1 is less than a first predetermined value α ₁ which is a positive value (step S3). If it is determined that the acceleration α is less than the first predetermined value α ₁ (S3: YES), the process goes to step S4. If it is determined that the acceleration α is not less than the first predetermined value α ₁ (S3: NO), the condition determiner 43 determines that the driving condition is not met, and determines that the command is invalid (step S20).
The condition determiner 43 determines whether or not the acceleration α is more than a second predetermined value α ₂ which is a negative value (step S4). In other words, in this step, it is determined whether or not the deceleration falls within an allowable range. If the extent of deceleration is relatively small and it is determined that the acceleration α is more than the second predetermined value α ₂ (S4: YES), the process goes to step S5. On the other hand, if the extent of deceleration is relatively large and the acceleration α is not more than the second predetermined value α ₂ (S4: NO), the condition determiner 43 determines that the driving condition is not met, and determines that the command is invalid (step S20).
As described above, in step S3 and step S4, the condition determiner 43 also serves as an acceleration determiner configured to determine whether or not the acceleration is the predetermined acceleration. In step S3 and step S4, the acceleration α may be detected based on signals from an exclusive acceleration sensor (not shown), or may be obtained by temporal differentiation of the vehicle speed detected by the signals from the vehicle speed sensor 36.
Alternatively, by using the opening degree of the throttle valve 21 which is detected by the throttle valve position sensor 32, a determination process similar to the predetermined process using the acceleration α to be compared to the predetermined value, can be performed. The motorcycle 1 may be typically accelerated when the opening degree of the throttle valve 21 is larger than a set throttle valve opening degree with which the motorcycle 1 can drive at a constant speed on a flat road. In view of this, the acceleration α is calculated from a deviation between the set throttle valve opening degree and the opening degree of throttle valve 21 which is detected by the throttle valve position sensor 32. The calculated acceleration α may be compared to the predetermined values α ₁ and α ₂ by utilizing a relationship in which the acceleration increases as the deviation increases. In this case, the value of the set throttle valve opening degree may be set and changed according to the engine speed and the transmission gear.
In the manner as described above, by using the vehicle speed or the throttle valve opening degree, the engine speed and the transmission gear, a sensor exclusive for detection of the acceleration may be omitted. As a result, the number of components and a manufacturing cost are reduced.
The condition determiner 43 determines whether or not the driving power transmission path 25 is disconnected (step S5). As defined herein, the state where the driving power transmission path 25 is disconnected refers to a state where the driving power of the engine 14 is not transmitted to the rear wheel 3 which is a driving wheel of the motorcycle 1, and includes, for example, a state where the clutch 28 is disengaged not to permit the driving power to be transmitted or a state where the neutral gear is set in transmission 15. If it is determined that the driving power transmission path 25 is disconnected (S5 :YES), the condition determiner 43 determines that the driving condition is met and the command is valid (step S10). On the other hand, if it is determined that the driving power transmission path 25 is connected (S5: NO), the process goes to step S6.
As described above, in the state where the clutch 28 is disengaged or the state where the neutral gear is set in the transmission 15, the driving power transmission path 25 is disconnected. Therefore, when it is determined that the clutch operation switch 35 detects that the clutch lever 8 has been operated or the gear position sensor 34 detects that the neutral gear is set in the transmission 15, it may be determined that the driving power transmission path 25 is disconnected. On the other hand, when it is determined that the clutch operation switch 35 detects that the clutch lever 8 has not been operated or the gear position sensor 34 detects that a gear other the neutral gear is set in the transmission 15, it may be determined that the driving power transmission path 25 is connected.
In step S6, the condition determiner 43 determines whether or not a transmission gear ratio r in the transmission 15 is less than a predetermined reduction gear ratio r _x which is not more than a maximum reduction gear ratio r ₁ which can be set. If it is determined that the transmission gear ratio r is less than the predetermined reduction gear ratio r _x (S6: YES), the condition determiner 43 determines that the driving condition is met and determines that the command is valid (step S10). On the other hand, if it is determined that the transmission gear ratio r is not less than the predetermined reduction gear ratio r _x (S6: NO), the condition determiner 43 determines that the driving condition is not met and determines that the command is invalid (step S20).
The maximum reduction gear ratio r ₁ which can be set, which is used in step S6 means a reduction gear ratio in a first gear which is the lowest gear. The predetermined reduction gear ratio r _x may be set to, for example, a reduction gear ratio in a second gear. In this example, if a third gear or higher gear is set in the transmission 15, the process goes to step S10, whereas if a second gear or lower gear is set in the transmission 15, the process goes to step S20. That is, in step S6, it is determined whether or not a current gear set in the transmission 15 which is capable of selecting any one gear position from among a plurality of forward gears is less than a predetermined gear. Therefore, the condition determiner 43 is configured to perform the determination process based on the gear position detected by the gear position sensor 34 without performing a process for calculating the reduction gear ratio.
As explained above, the condition determiner 43 of this embodiment determines that the command is valid if the motorcycle 1 is in a stopped state (step S1). A driving state fluctuation will not occur if the control mode is switched in the stopped state. Therefore, the control mode can be switched without affecting the driving feel.
If it is determined that the vehicle speed V is more than 0 and does not fall within the predetermined speed range, the condition determiner 43 determines that the command is invalid (step S2). The first vehicle speed V ₁ which is the lower limit value of the speed range, which is used in step S2, is a speed set in a starting range, and may be set to a vehicle speed corresponding to for example, a first gear, and corresponding to an engine speed at which an output torque is higher, for example, 20km/h. The second vehicle speed V ₂ which is the upper limit value of the speed range may be set to a speed at which restricting a fuel consumption amount under engine control does not substantially occur. Under this setting, if the vehicle speed V is lower and outside the speed range, switching of the control mode in the starting range in which acceleration is required is inhibited and a driving state fluctuation due to the switching of the control mode can be prevented. If the vehicle speed V is higher and outside the speed range, the switching of the control mode will not be effective. Therefore, occurrence of an unnecessary switching operation in this situation is prevented. During the starting, the switching of the normal mode to the economy mode is inhibited, and the motorcycle 1 can start with a higher output torque than in the economy mode. This can reduce a time that lapses from the motorcycle 1 has started until the vehicle speed reaches a speed at which the motorcycle 1 can drive in a stable state, and hence improves convenience.
If it is determined that the motorcycle 1 is in a transient state in which the motorcycle 1 is not driving at a constant speed, the condition determiner 43 determines that the command is invalid (step S3, S4). In this transient state, there is a chance that a target fuel amount is different between the control modes regardless of the same input, and as a result, a propulsive force applied to the rear wheel 3 is different, causing a difference in actual speed and actual acceleration speed. Since it is determined that the command is invalid in the transient state, driving state fluctuation due to the switching of the control mode can be suppressed.
If the deceleration is larger, the condition determiner 43 determines that the command is invalid (step S4). Therefore, the switching of the control mode is inhibited in the driving state in which an engine brake is operating, for example. As a result, the driving state fluctuation which would be caused by the switching of the control mode, does not occur in the state where the engine brake is operating.
In step S3 and step S4, it is determined whether or not the driving state is the transient state, and it is determined that the command is invalid if the driving state is the transient state. In other words, in step S3 and S4, it is determined whether or not the motorcycle 1 is driving at a substantially constant speed and it is determined that the command is not invalid if it is determined that the motorcycle 1 is driving at a substantially constant speed. The speed change due to the switching of the control mode can be made less when the motorcycle 1 is driving at a substantially constant speed than in the state where the driving state is the transient state, and the control mode can be switched without worsening driving feel. The first predetermined value α ₁[m/s²] may be set to a range of, for example, 0 < α ₁ < 5. The second predetermined value α ₂[m/s²] may be set to a range of, for example, -5 < α ₂ < 0. To determine whether or not the motorcycle 1 is driving at a constant speed, the predetermined values α ₁ and α ₂ used in steps S3 and S4 may be set to a value near 0.
The condition determiner 32 determines that the command is valid if it is determined that the driving power transmission path 25 is disconnected (step S5). In the state where the driving power transmission path 25 is disconnected, a change in the operation of the engine 14 due to the switching of the control mode is less likely to be transmitted to the rear wheel 3. This reduces a chance that a substantial driving state fluctuation occurs. Therefore, in this case, the switching of the control mode is permitted, and the control mode can be switched without worsening the driving feel during driving.
The condition determiner 32 determines that the command is invalid if it is determined that the driving power transmission path 25 is connected and the forward transmission gear set in the transmission 15 is a lower gear, whereas the condition determiner 32 determines that the command is valid if it is determined that the driving power transmission path 25 is connected and the forward transmission gear is a medium or high gear (step S6). When the lower gear is set in the transmission 15, typically, a torque transmitted from the engine 14 to the rear wheel 3 is large, and acceleration is required, for example, during starting. In these cases, the switching of the control mode is inhibited. Therefore, the driving state fluctuation due to the switching of the control mode can be suppressed and the motorcycle 1 can start with the driving state fluctuation lessened.
As described above, the condition determiner 43 determines whether the command is valid or invalid based on whether or not the current driving state meets any of the plurality of driving conditions, and the control mode is switched without worsening the driving feel if it is determined that the command is valid.
During driving, it is determined that the command is valid when all of the three driving conditions in step S2 to S4 are met and then either one of the two driving conditions in step S5 and S6 is met. Since the switching of the control mode is permitted when the various driving conditions are met, the driving state fluctuation due to the switching of the control mode can be suppressed sufficiently.
The flow of the determination process executed by the condition determiner 43 is not limited to the flow of Fig. 4. Fig. 5 is a flowchart showing an example useful for understanding the invention. In the flow chart of Fig. 5, a determination step regarding the vehicle speed (step S102) is changed as compared to the flowchart of Fig. 4 (also see step S2 in Fig. 4). In step S102, it is determined whether or not the vehicle speed V is not less than the first vehicle speed V1 which is more than 0. If it is determined that the vehicle speed V is not less than the first vehicle speed V1 (S102: YES), the process goes to step S3. On the other hand, if it is determined that the vehicle speed V is less than the first vehicle speed V1 (S102: NO), the process goes to step S5. In step S3, the determination step similar to that shown in Fig. 4 is performed, and if it is determined that the acceleration α is less than the first predetermined value α1 (S3: YES), the process goes to step S4, whereas if it is determined that the acceleration α is not less than the first predetermined value α1 (S3: NO), the process goes to step S5. In step S4, the determination step similar to that of Fig. 4 is performed. If it is determined that the acceleration α is more than the second predetermined value α2 (S4: YES), the process goes to step S10 and it is determined that the command is valid. On the other hand, if it is determined that the acceleration α is not more than the second predetermined value α2 (S4: NO), the process goes to step S5. In step S5, the determination step similar to that of Fig. 4 is performed. If it is determined that the driving power transmission path 25 is disconnected (S5 :YES), the process goes to step S10, whereas if it is determined that the driving power transmission path 25 is not disconnected (S5 :NO), the process goes to step S20, and it is determined that the command is invalid.
As described above, in this modification, if either one of the driving conditions that the motorcycle 1 is driving at a substantially constant speed (step S3 and step S4), and the driving power transmission path 25 is disconnected (step S5), the command for switching the control mode is permitted. As described above, if the driving power transmission path 25 is disconnected, there is a small chance that a change in the operation of the engine 14 is transmitted to the rear wheel 3 and causes driving state fluctuation. In the determination step of step S102, it is determined that the command is valid even when the vehicle speed V falls within the high-speed range.
As it may be observed from Fig. 5, in the example useful for understanding the invention, step S6 of Fig. 4 is omitted from the flow of Fig. 5. Although it is determined that the command is not invalid when the vehicle speed V falls within the high-speed range (step S102) in the flowchart of Fig. 5, steps S2 and S102 may be omitted in the example useful for understanding the invention if it is determined that the command is not invalid when the vehicle speed V falls within the starting range.
The driving state fluctuation associated with fluctuation in the engine driving power which is caused by the switching of the control mode tends to occur in a relatively lightweight straddle-type vehicle such as the motorcycle 1. For this reason, the application of the engine control system 50 of this embodiment to the straddle-type vehicle will be very effective. The straddle-type vehicle includes a personal watercraft, a buggy, etc, in addition to the motorcycle.
Although the embodiment of the present invention has been described, the above configuration may be changed within the scope of the appended claims.
A display device for displaying a reason why the mode switching command is invalid may be coupled to the output of the electronic control unit 19 and may be attached on the instrument panel. Furthermore, the display device may be configured to display a different content according to the reason when the electronic control unit 19 determines that the mode switching command is invalid based on the driving condition. In this case, the driver can know the reason why the mode switching command is invalid, and convenience is improved.
Regarding determination as to whether or not the driving condition is met, the mode switching command need not be determined as invalid during deceleration of the motorcycle 1. In other words, the determination step S4 may be omitted from the flowchart of the determination process shown in Fig. 4.
Although in the above embodiment shown in Fig. 4, the determination step for the driving condition regarding negative acceleration is performed in step S4, a step for determining whether or not the engine brake is operating to decelerate the motorcycle 1 may be added to this determination step. To be specific, it may be determined whether or not a brake operation member has been operated and a current engine speed is higher than an engine speed in a state where a throttle grip is closed, based on the detection values from the engine speed sensor and the brake sensor. If it is determined as YES, it may be determined that the engine brake is operating to decelerate the motorcycle 1. It may be determined that the driving condition is not met if the acceleration α of the vehicle is not more than the second predetermined value α ₂, after it is determined that the engine brake is operating. This makes it possible to inhibit the switching of the control mode during the engine braking operation in which the driving state fluctuation due the switching of the control mode tends to occur, and to permit the switching of the control mode during deceleration of the motorcycle 1 other than a state where the engine brake is operating. Thus, convenience is improved.
When the ignition switch is tuned ON and the engine re-starts without inputting the command for switching the control mode with the mode select switch in a case where the ignition switch is turned OFF and the engine is stopped in the economy mode, the mode setting section may set the normal mode at the re-start. When the ignition switch is tuned ON and the engine re-starts after the command for switching the control mode to the economy mode is input with the mode select switch, the mode setting section may set the economy mode at the re-start.
Although switching between ON and OFF of the economy mode has been described above, the switching of the control mode may be permitted in the same manner only when a predetermined driving condition is met, in a case where switching between ON and OFF of two or mode control modes regarding the driving state, from among a power restricting mode, a CBS (combination breaking system) mode, a race mode (also called sport mode), a highway mode, a supercharger activation mode, a traction control, and others, occurs, and thereby, the driving state fluctuation due to the switching of the control mode can be suppressed. As should be readily appreciated, the present invention is suitably applicable to switching between ON and OFF of a plurality of control modes. Although in the above embodiment, two control modes which are different in engine driving power property has been described, switching between ON and OFF of three or more control modes may be permitted according to the driving condition. The present invention is applicable in the same manner to a case where the control mode is automatically switched as well as a case where the control mode is switched in response to the command input by the driver. The present invention is applicable to a case where the operation command value is changed continuously as well as to a case where the operation command value is obtained discontinuously after switching of the control mode.
The configuration of the engine 14 and the configuration of the transmission 15 are not limited to those described above. The engine control system for the vehicle of the present invention is applicable to other vehicles such as four-wheeled vehicles and all terrain vehicles (ATVs) as well as motorcycles and straddle-type vehicles.
As described above, the engine control system of the present invention has an advantage that driving feel is improved, and is applicable to vehicles such as motorcycles and others which can effectively use the present invention.

Claims

An engine control system (50) for a vehicle (1), which is configured to control an engine (14) using a plurality of control modes, comprising:
a controller (19) configured to selectively set a first control mode or a second control mode and to control the engine (14) using the set control mode, the first control mode and the second control mode being provided such that the engine (14) is operable with a smaller fuel amount in the second control mode than in the first control mode; and

a mode switching device (37) for switching the control mode set in the controller (19) between the first control mode and the second control mode;

wherein the mode switching device (37) includes an operation member which is operated by a driver,

wherein the controller (19) is configured to determine that the command for switching the control mode has been input only when an operation time for which the operation member is operated by the driver falls within a predetermined time range which is not less than a predetermined first time and not more than a predetermined second time,

wherein the controller (19) is configured to determine that a command for switching the control mode is valid if a predetermined driving condition is met, in response to the command input to the mode switching device (37), and to determine that the command is invalid if the predetermined driving condition is not met, in response to the command input to the mode switching device (37)

characterized in that the engine control system (50) comprises an acceleration determiner (43) configured to determine whether or not the vehicle (1) is driving with a predetermined acceleration, a driving power transmission determiner configured to determine whether or not a transmission path (25) of a driving power generated in the engine (14) is disconnected, and a gear position sensor (34) for detecting a gear position of a transmission (15) mounted in the vehicle (1);

in that the predetermined driving condition includes a first condition that the vehicle (1) is driving with an acceleration less than the predetermined acceleration, and a second condition that the transmission path (25) is disconnected or the gear position detected by the gear position sensor (34) is a gear position corresponding to a reduction gear ratio less than a predetermined reduction gear ratio which is not more than a maximum reduction gear ratio; and

in that the predetermined driving condition is met when the first condition and the second condition are met.
The engine control system for the vehicle according to Claim 1, further comprising:
a vehicle speed sensor (36) for detecting a vehicle speed;

wherein the predetermined driving condition includes a third condition that the vehicle speed detected by the vehicle speed sensor (36) falls within a predetermined speed range which is not less than a predetermined first speed and not more than a predetermined second speed, and

the predetermined driving condition is met when the first condition, the second condition, and the third condition are met,

the predetermined first speed is higher than zero and the second predetermined speed is set to a value larger than a value of the predetermined first speed.
The engine control system for the vehicle according to Claim 1 or 2, further comprising:
a sensor (43) for outputting a detection value used to determine whether or not a predetermined driving condition is met; and

an abnormality determiner (42) configured to determine whether or not abnormality occurs in the sensor (43); wherein

the controller (19) is configured to restrict switching of the control mode when the abnormality determiner (42) determines that the abnormality occurs in the sensor (43).
The engine control system for the vehicle according to any one of Claims 1 to 3, further comprising:
a display device (38);

wherein the controller (19) is configured to cause the display device (38) to conduct display in a different manner according to the set control mode.
The engine control system for the vehicle according to Claim 1, wherein
the controller (19) is configured to set the first control mode at re-start of the engine (14) if the command is not input to the mode switching device (37) before the engine (14) re-starts, and to set the second control mode at re-start of the engine (14) when a command for switching the control mode to the second control mode is input to the mode switching device (37) before the engine (14) re-starts, when the engine (14) is stopped in a state where the second control mode is set.