The disclosure of Japanese Patent Application No. 2011-063200 filed on Mar. 22, 2011 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a vehicle control apparatus and a vehicle control method that limit a traveling speed of a vehicle when the vehicle backs up.
2. Description of Related Art
When a vehicle backs up, a passenger assumes a less natural posture or has a narrower visual field than when the vehicle travels forward. Therefore, the driving operation to back up the vehicle is more difficult than the driving operation to cause the vehicle to travel forward. Thus, it is desirable to facilitate the driving operation of the vehicle by limiting the traveling speed of the vehicle to prevent the traveling speed from becoming too high when the vehicle backs up.
Japanese Patent Application Publication No. 59-155545 (JP-A-59-155545) proposes the execution of vehicle speed limiting control of limiting the traveling speed of the vehicle to a speed equal to or lower than a predetermined speed at the time when a reverse travel (in which the vehicle backs up) has been selected.
In general, it is detected whether the forward travel of the vehicle or the reverse travel of the vehicle has been selected through a driving operation by a passenger, by a sensor or a switch that is fitted to the vehicle, for example, a sensor for detecting an operation mode of a transmission, a switch for detecting an operated position of a shift lever, or the like. Thus, in the case where noise is superimposed on an output signal of such a sensor (or such a switch) or a control apparatus that acquires the output signal of the sensor or the sensor itself malfunctions, it may be erroneously determined that the reverse travel of the vehicle has been selected, although a driving operation of selecting the reverse travel of the vehicle has actually not been performed.
In the apparatus described in JP-A-59-155545, when the erroneous determination as described above is made and the traveling speed is limited through the vehicle speed limiting control while the vehicle travels forward, the traveling speed of the vehicle may unnecessarily fall, or the degree of the fall in the traveling speed may increase to cause a shock to the vehicle when the traveling speed is high. As a result, a deterioration in drivability may be caused.
The invention provides a vehicle control apparatus and a vehicle control method that can restrain a deterioration in drivability in the case where it is erroneously detected that the reverse travel of a vehicle has been selected while the vehicle travels forward.
A first aspect of the invention is a vehicle control apparatus including a detection unit that detects whether or not a reverse driving operation to select a reverse travel of a vehicle has been performed, wherein the vehicle backs up in the reverse traveling, and a control unit that executes vehicle speed limiting control of limiting a traveling speed of the vehicle to a speed equal to or lower than a first speed when the vehicle backs up, and prohibits execution of the vehicle speed limiting control when the traveling speed of the vehicle is equal to or higher than a second speed that is higher than the first speed and the detection unit detects that the reverse driving operation has been performed.
A second aspect of the invention is a vehicle control method including detecting whether or not a reverse driving operation to select a reverse travel of a vehicle has been performed, wherein the vehicle backs up in the reverse travel, executing vehicle speed limiting control of limiting a traveling speed of the vehicle to a speed equal to or lower than a first speed during back-up of the vehicle, and prohibiting execution of the vehicle speed limiting control when the traveling speed of the vehicle is equal to or higher than a second speed that is higher than the first speed and when it is detected that the reverse driving operation has been performed.
According to the first and second aspects of the invention, in an apparatus that executes vehicle speed limiting control of limiting a traveling speed of a vehicle when the vehicle backs up, an unnecessary fall in the traveling speed or the occurrence of a shock can be restrained in the case where it is erroneously detected that the reverse travel of the vehicle has been selected while the vehicle travels forward. As a result, a deterioration in drivability can be restrained.
The foregoing and further objects, features and advantages of the invention will become apparent from the following description of example embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:
A vehicle control apparatus according to the first embodiment of the invention will be described hereinafter. As shown in
The vehicle 10 is mounted with a shift device 17 for changing the operation mode of the continuously variable transmission 14. In performing a driving operation of the vehicle 10, the aforementioned shift device 17 (more specifically, a shift lever 17A) is operated to one of a drive (forward) position (a D position), a reverse position (an R position), a park position (a P position), and a neutral position (an N position) through an operation by a passenger. More specifically, the D position is selected when causing the vehicle 10 to travel forward, the R position is selected when backing up the vehicle 10, the P position is selected when parking the vehicle 10, and the N position is selected when shutting off power transmission from the internal combustion engine 11 to the axle 15.
Various sensors for detecting a driving state of the vehicle 10 is fitted to the vehicle 10. More specifically, speed sensors 21 for detecting rotational speeds of the respective wheels 16 are fitted in the vicinity of the wheels 16. As the speed sensors 21, speed sensors that cannot detect rotational directions, namely, speed sensors that detect absolute values of rotational speeds of the wheels 16 are adopted. In this embodiment of the invention, a traveling speed (a vehicle speed SPD) of the vehicle 10 is obtained on the basis of output signals of the speed sensors 21. Incidentally, the vehicle speed SPD may be an average of the rotational speeds of the respective wheels 16 detected by the speed sensors 21, or a maximum value of the rotational speeds of the respective wheels 16, for example.
The shift device 17 is provided with switches 22, 23, 24, and 25 for detecting an operated position of the shift device 17. To be more specific, the shift device 17 is fitted with the D switch 22 for detecting that the shift device 17 has been operated to the D position, the R switch 23 for detecting that the shift device 17 has been operated to the R position, the P switch 24 for detecting that the shift device 17 has been operated to the P position, and the N switch 25 for detecting that the shift device 17 has been operated to the N position.
Further, the vehicle 10 is also fitted with an accelerator sensor 26 for detecting an operation amount AC of an accelerator pedal 18, a brake switch 27 for detecting the presence or absence of an operation of depressing a brake pedal 19, and the like.
The vehicle 10 is fitted with an electronic control unit 20 that is mainly composed of, for example, a microcomputer. The electronic control unit 20 acquires output signals of the various sensors, performs various calculations, and executes various kinds of control such as operation control of the internal combustion engine 11, operation control of the continuously variable transmission 14, and the like, on the basis of results of the calculations.
The operation control of the continuously variable transmission 14 is executed as follows. First of all, a control target value (a target rotational speed Tpr) for the rotational speed of a primary pulley 14A is set on the basis of a depression operation amount AC of the accelerator pedal 18, the vehicle speed SPD, and an operation state of the brake pedal 19. Then, the effective diameter of the primary pulley 14A is adjusted such that an actual rotational speed of the primary pulley 14A matches the target rotational speed Tpr. Thus, the speed ratio is automatically and steplessly changed in accordance with the driving state of the vehicle 10.
In this embodiment of the invention, as one of various kinds of control executed by the electronic control unit 20, vehicle speed limiting control of limiting the traveling speed of the vehicle 10 is executed when the vehicle 10 backs up. The vehicle speed limiting control is executed as follows.
First of all, it is determined whether or not the shift device 17 has been operated to back up the vehicle 10. That is, it is determined whether or not the driving operation to select the reverse travel of the vehicle 10 is performed. The determination is made on the basis of output signals of the respective switches 22, 23, 24, and 25, with which the shift device 17 is provided. In this embodiment of the invention, when the R switch 23 has been turned on and the D switch 22 has been turned off, it is determined that the shift device 17 has been operated to back up the vehicle 10. In this embodiment of the invention, the D switch 22, the R switch 23, and the electronic control unit 20 function as a detection unit.
When it is determined that the shift device 17 has not been operated to back up the vehicle 10, namely, when the operated position of the shift device 17 (hereinafter referred to as “a shift position”) is a position other than the R position, the processing of limiting the traveling speed of the vehicle 10 is not performed.
On the other hand, when it is determined that the shift device 17 has been operated to back up the vehicle 10, in other words, when it is determined that the shift position is the R position, the following processing is performed to limit the traveling speed of the vehicle 10.
In the vehicle speed limiting control, if the vehicle speed SPD is equal to or higher than a first first predetermined speed V1 (e.g., 20 km/h), feedback control of the output torque of the internal combustion engine 11 (more specifically, the opening degree of the throttle valve 13) is executed on the basis of the difference between the vehicle speed SPD and the first predetermined speed V1. If the vehicle speed SPD is lower than the first predetermined speed V1, the feedback control based on the aforementioned difference is not executed.
Through the execution of the vehicle speed limiting control, the vehicle speed SPD when the vehicle 10 backs up is limited to a speed equal to or lower than the first predetermined speed V1. In this embodiment of the invention, the aforementioned first predetermined speed V1 regarded as a first speed.
In the operation control for the continuously variable transmission 14 of this embodiment of the invention, regardless of whether the shift position is the D position or the R position, the speed ratio is automatically and steplessly changed in accordance with the driving state of the vehicle 10. Thus, the speed ratio in the reverse travel of the vehicle tends to be smaller than in a vehicle mounted with a multistage transmission having a shift speed for the reverse travel. As a result, the vehicle speed SPD tends to be high when the vehicle 10 backs up. For the above reason, there is a great demand for the aforementioned vehicle speed limiting control in the vehicle 10. In this embodiment of the invention, the vehicle speed limiting control is executed in the vehicle 10 mounted with the continuously variable transmission 14, so that the vehicle speed SPD when the vehicle 10 backs up is limited so as not to become excessively high.
In the vehicle speed limiting control, it is determined, on the basis of output signals of the D switch 22 and the R switch 23 that are fitted to the shift device 17, whether or not the shift device 17 has been operated to back up the vehicle 10. Thus, in the case where noise is superimposed on the output signals of the D switch 22 and the R switch 23 or the D switch 22 and the R switch 23 malfunction, it may be erroneously determined that the reverse travel has been selected, although a driving operation for selecting the reverse travel has not actually been performed. When such an erroneous determination is made and the vehicle speed SPD is limited through the execution of the vehicle speed limiting control while the vehicle 10 travels forward, the vehicle speed SPD may unnecessarily fall, or the degree of fall in the vehicle speed SPD may increases to cause a shock to the vehicle 10 when the vehicle speed SPD is high. As a result, a deterioration in drivability may be caused.
Thus, in this embodiment of the invention, in the case where the vehicle speed SPD is equal to or higher than a second predetermined speed V1 (e.g., 30 km/h) that is higher than the first predetermined speed VI, when an operation of the shift device 17 to the R position through the D switch 22 and the R switch 23 is detected, the execution of the aforementioned vehicle speed limiting control is prohibited.
In driving control of the vehicle 10, when the vehicle speed SPD is equal to or higher than the second predetermined speed V1, the possibility of the shift device 17 being operated to the R position through a driving operation is extremely low. Accordingly, it is highly likely that a determination that such an operation has been performed is an erroneous determination. In this embodiment of the invention, in the case where an operation of the shift device 17 to the R position is detected when the vehicle speed SPD is equal to or higher than the second predetermined speed V1, a determination that the shift device 17 has been operated to back up the vehicle 10 is considered to be erroneous, and the execution of the vehicle speed limiting control is prohibited.
The procedure of performing a processing of prohibiting the execution of the vehicle speed limiting control (an execution prohibition processing) will be described in detail with reference to a flowchart shown in
As shown in
[First Condition] It is determined that the shift position is the R position (step S101).
[Second Condition] The vehicle speed SPD is lower than the second predetermined speed V1 (step S102).
As the aforementioned second predetermined speed V1, a certain value that satisfies both the following requirements is obtained in advance and stored into the electronic control unit 20.
[First Requirement] The second predetermined speed V1 is an upper-limit speed (or a speed slightly lower than the upper-limit speed) in a vehicle speed range in which a shock to the vehicle 10, occurring when the execution of the vehicle speed limiting control is started, may not cause the deterioration in drivability.
[Second Requirement] In the case where the vehicle speed SPD overshoots the first predetermined speed V1 when the execution of the vehicle speed limiting control is started in response to the vehicle speed SPD having become equal to or higher than the first predetermined speed V1 in backing up the vehicle 10, the overshooting vehicle speed SPD do not exceed the second predetermined speed V1.
Then, when the first condition is not satisfied (step S101: NO), it is determined that there is no need to execute the vehicle speed limiting control because the shift position is not the R position, and therefore, a vehicle speed limiting flag is turned off (step S103). In this embodiment of the invention, when the vehicle speed limiting flag is turned off, the vehicle speed limiting control is not executed.
Thereafter, when both the first condition and the second condition are both satisfied (“YES” in both step S101 and step S102) through the repetitious performance of this processing, the vehicle speed limiting flag is turned on (step S104). In this embodiment of the invention, when the vehicle speed limiting flag is turned on, the vehicle speed limiting control is executed.
A mode of limiting the vehicle speed SPD in this case (a first example) will be described with reference to a timing chart shown in
On the other hand, when the first condition is satisfied (step S101: YES) and the second condition is not satisfied (step S102: NO), the vehicle speed limiting flag is turned off (step S103), and the vehicle speed limiting control is not executed.
A mode of limiting the vehicle speed SPD in this case (a second example) will be described with reference to a timing chart shown in
As described hitherto, according to this processing, the vehicle speed limiting control of limiting the vehicle speed SPD is executed in backing up the vehicle 10, but an unnecessary fall in the vehicle speed SPD or the occurrence of a shock can be restrained in the case where it is erroneously detected that the reverse travel of the vehicle 10 has been selected while the vehicle 10 travels forward. Consequently, the drivability can be restrained from deteriorating.
After the first condition and the second condition are both satisfied (“YES” in both step S101 and step S102) and the execution of the vehicle speed limiting control is prohibited, when the vehicle speed SPD falls to become lower than the second predetermined speed V1 (step S102: YES), the vehicle speed limiting flag is turned on (step S104). That is, in this case, the prohibition of the execution of the vehicle speed limiting control is canceled, and the execution of the vehicle speed limiting control is started.
A mode of limiting the vehicle speed SPD in this case (a third example) will be described with reference to a timing chart shown in
As described above, according to this embodiment of the invention, the following effects are obtained.
(1) When the vehicle speed SPD is equal to or higher than the second predetermined speed V1 and an operation of the shift device 17 to the R position is detected on the basis of output signals of the D switch 22 and the R switch 23, the execution of the vehicle speed limiting control is prohibited. Thus, in an apparatus in which the vehicle speed limiting control of limiting the vehicle speed SPD when the vehicle 10 backs up is executed, the drivability can be restrained from deteriorating in the case where it is erroneously detected that the reverse travel of the vehicle 10 has been selected while the vehicle 10 travels forward.
(2) On the condition that the vehicle speed SPD have become low enough not to cause a great shock even in the case where the vehicle speed limiting control is executed, the prohibition of the execution of the vehicle speed limiting control can be canceled. Accordingly, a shock can be restrained from occurring as a result of the cancellation of the prohibition of the execution of the vehicle speed limiting control.
(3) In the vehicle 10 which is mounted with the continuously variable transmission 14, whose vehicle speed SPD therefore tends to be high when the vehicle 10 backs up, and in which there is a great demand for the vehicle speed limiting control, the vehicle speed limiting control is executed. Then, the drivability can be suitably restrained from deteriorating in the case where it is erroneously detected that the reverse travel of the vehicle 10 has been selected while the vehicle 10 travels forward during the execution of the vehicle speed limiting control.
A vehicle control apparatus according to the second embodiment of the invention will be described hereinafter focusing mainly on differences from the first embodiment of the invention. In the following, components identical to those of the first embodiment of the invention will be denoted by the same reference symbols respectively, and detailed description thereof will be omitted.
The vehicle control apparatus according to the second embodiment of the invention is different from the vehicle control apparatus according to the first embodiment of the invention in the mode of performing the execution prohibition processing. The execution prohibition processing according to the second embodiment of the invention will be concretely described hereinafter.
As shown in
When the first condition is satisfied (step S101: YES) and the second condition is not satisfied (step S102: NO), the prohibition flag is turned on (step S202), and the vehicle speed limiting flag is turned off (step S103) to prohibit the execution of the vehicle speed limiting control. As described hitherto, in this processing, the prohibition flag is turned on at a timing when the execution of the vehicle speed limiting control is prohibited.
After the prohibition flag is turned on (step S201: NO) as described above, the prohibition flag is held on unless one of a third condition and a fourth condition shown below is satisfied (step S203: NO) (the process of step S204 is skipped). Therefore, the processes from step S101 to step S104 are not carried out, and the vehicle speed limiting flag is held off to continue to prohibit the execution of the vehicle speed limiting control.
[Third Condition] It is determined that the shift position is a position other than the R position.
[Fourth condition] The vehicle speed SPD is equal to or lower than the first predetermined speed V1.
Thereafter, when one of the third condition and the fourth condition is satisfied (step S203: YES) through the repetitive performance of this processing, the prohibition flag is turned off (step S204). Thus, after the prohibition flag is turned off (step S201: YES), the processes of step S101 to step S104 are carried out. That is, the prohibition of the execution of the vehicle speed limiting control is canceled.
An operation achieved by performing the aforementioned execution prohibition processing will be described hereinafter with reference to a timing chart shown in
Thereafter, when the vehicle speed SPD further falls to become equal to or lower than the first predetermined speed VI (at a time t43), the prohibition flag is turned off to cancel the prohibition of the execution of the vehicle speed limiting control. As described hitherto, in this embodiment of the invention, the prohibition of the execution of the vehicle speed limiting control is cancelled on the condition that the vehicle speed SPD have fallen to become equal to or lower than the first predetermined speed V1.
In the driving control of the vehicle 10, the possibility of a driving operation of operating the shift device 17 to the R position being performed when the vehicle speed SPD is equal to or higher than the second predetermined speed V1 is extremely low. Therefore, it is highly likely that a determination that such an operation has been performed is an erroneous determination.
On the other hand, according to this embodiment of the invention, when the vehicle speed SPD has become lower than the second predetermined speed V1 after the execution of the vehicle speed limiting control is prohibited, the credibility of a determination itself that the shift position is the R position is considered to be low, and the prohibition of the execution of the vehicle speed limiting control is continued over a period to a time when the vehicle speed SPD further falls to become equal to or lower than the first predetermined speed V1. Thus, when it is erroneously determined that the shift position is the R position, the vehicle speed limiting control is reliably restrained from being executed on the basis of the erroneous determination.
Further, in this embodiment of the invention, in the case where it is determined that the shift position becomes a position other than the R position after the execution of the vehicle speed limiting control is prohibited as well, the prohibition flag is turned off, and the prohibition of the execution Of the vehicle speed limiting cool is cancelled. Thus, on the condition that a situation where there is no need to execute the vehicle speed limiting control arise, the prohibition of the execution of the vehicle speed limiting control can be cancelled.
As described above, according to this embodiment of the invention, in addition to the effects described in the foregoing remarks (1) and (3), effects described in the following remarks (4) and (5) are obtained.
(4) The prohibition of the execution of the vehicle speed limiting control is canceled on the condition that the vehicle speed SPD have fallen to become equal to or lower than the first predetermined speed V1. Therefore, in the case where it is erroneously determined that the shift position is the R position, the vehicle speed limiting control can be reliably restrained from being executed on the basis of the erroneous determination.
(5) The prohibition of the execution of the vehicle speed limiting control can be canceled on the condition that a situation where there is no need to execute the vehicle speed limiting control arise.
It should be noted that each of the foregoing embodiments of the invention may be modified and implemented as follows.
In accordance with the prohibition of the execution of the vehicle speed limiting control, a warning lamp fitted in a vehicle interior may be lit up, or a history of the prohibition of the execution may be stored into a memory of the electronic control unit 20. The mode of executing the vehicle speed limiting control is not limited to the execution of the feedback control of the opening degree of the throttle valve 13. The mode of executing the vehicle speed limiting control may be arbitrarily modified. For example, the vehicle speed limiting control may be executed by executing the feedback control of the fuel injection amount, temporarily stopping fuel injection, or the like. That is, any mode in which the traveling speed of the vehicle 10 is limited to a speed equal to or lower than a predetermined speed during the back-up of the vehicle 10 is acceptable.
Instead of detecting the vehicle speed SPD on the basis of the output signals of the respective speed sensors 21, it is also applicable to provide a axle speed sensor that detects a rotational speed of the axle 15 and detect the vehicle speed SPD on the basis of an output signal of the axle speed sensor, or to provide a transmission output shaft speed sensor that detects a rotational speed of the output shaft of the continuously variable transmission 14 and detect the vehicle speed SPD on the basis of an output signal of the transmission output shaft speed sensor.
It is also applicable to provide a operation mode sensor (or a switch) for detecting an operation mode of the continuously variable transmission 14, and detect an operated position of the shift device 17 on the basis of an output signal of the operation mode sensor.
The conditions for prohibiting the execution of the vehicle speed limiting control are not limited to the first condition and the second condition, but may be arbitrarily, modified. For example, it is possible to prohibit the execution of the vehicle speed limiting control on the condition that a fifth condition shown below is satisfied during the last performance of a processing that is performed on a predetermined cycle and a sixth condition shown below is satisfied during the current performance of the processing.
[Fifth Condition] It is determined that the shift position is in the D position and the vehicle speed SPD is equal to or higher than the second predetermined speed V1.
[Sixth Condition] It is determined that the shift position is in the R position.
That is, it is applicable to adopt any condition that prohibits the execution of the vehicle speed limiting control when it is detected that the driving operation of selecting the reverse travel of the vehicle 10 has been performed in a situation where the vehicle speed SPD is equal to or higher than the second predetermined speed V1.
The vehicle control apparatus according to each of the foregoing embodiments of the invention may be applied not only to the vehicle 10 mounted with the belt-type continuously variable transmission 14 but also to a vehicle mounted with a toroidal-type continuously variable transmission.
The invention may be applied to a vehicle mounted with a multi-stage automatic transmission as well as a vehicle mounted with a continuously variable transmission. Further, the invention may be applied not only to a vehicle mounted with an automatic transmission but also to a vehicle mounted with a manual transmission. That is, the invention may be applied to any apparatus that executes the vehicle speed limiting control of limiting the traveling speed of a vehicle to a speed equal to or lower than a predetermined speed when the reverse travel of the vehicle is selected.
Number | Date | Country | Kind |
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2011-063200 | Mar 2011 | JP | national |