vehicle

Abstract

Vehicle (10), comprising: a fuel cell (100) designed to receive a supply of fuel gas and generate electrical power; an electric motor (150) designed for propulsion using the electrical power generated by the fuel cell (100); a mode selector (30) designed to selectively set a driving mode of the vehicle (10) when the accelerator (20) is not engaged between a normal mode, which decelerates the vehicle with a deceleration force necessary to slow the vehicle (10) in response to the driver pressing down a brake pedal (22), covered by a regenerative braking force obtained by a regenerative control of the electric motor (150), and a deceleration boost mode, which decelerates the vehicle (10) in response to the driver releasing the accelerator (20) with a deceleration force higher than the deceleration force in the normal mode; and a control device (200) designed to perform regenerative control of the electric motor (150) in normal mode or to perform deceleration control in deceleration boost mode, generating the deceleration force to slow down the vehicle (10) in the drive mode set by the mode selector (30), wherein the control unit (200) changes the drive mode from the deceleration boost mode to the normal mode when, in the drive mode set to the deceleration boost mode, an accelerator adjustment travel based on a depressing of the accelerator (20) by the driver becomes higher than a cancellation threshold value (As1, As2).

Description

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from JP 2016 - 096 609 A, filed on November 12, 2014. GENERAL STATE OF THE ART

[0002] The present invention relates to a vehicle. RELATED TECHNOLOGY

[0003] A fuel cell is installed in a vehicle together with an electric motor to generate electrical power using supplied fuel gas and supply the generated electrical power to the electric motor coupled to a wheel axle of the vehicle. The electric motor is driven by the electrical power generated by the fuel cell while regenerating electrical power under regeneration control to brake the wheel axle. The vehicle is decelerated as needed using the braking force generated during driving by the electric motor's regeneration control. Braking through regeneration control is mainly used in the following two situations: 1) When the driver presses a brake pedal to slow the vehicle; in this case, the amount of regenerative braking is controlled to be proportional to the amount the driver presses the brake pedal. 2) when the driver moves a gear lever to a braking position provided in a gear change device.

[0004] In this case, like engine braking in a conventional internal combustion engine vehicle, a certain braking force is applied to the wheel axle (drive shaft) through regenerative control, regardless of the driver's brake pedal operation. When the driver steps on the brake pedal in this state, in addition to the braking force applied to the wheel axle, a braking force corresponding to the amount by which the driver depresses the brake pedal is applied to the wheel axle. Thus, this allows the driver to brake the vehicle with a deceleration force greater than the deceleration force during normal driving. The braking force corresponding to the amount by which the driver depresses the brake pedal increases with an increase in the initial regeneration level.In cases where the braking force is insufficient through regenerative braking alone, a hydraulic brake or the like can be used to generate a higher deceleration force and decelerate the vehicle with the higher deceleration force. Such a deceleration control technique is described, for example, in JP 2007-123169A.

[0005] This proposed deceleration control technique controls the vehicle's braking force by adding a certain amount of braking force to the normal braking force when the driver shifts the gear lever to the braking position. However, this deceleration technique requires the driver to return the gear lever to the drive position to change the drive mode from a deceleration-augmentation drive mode with additional deceleration to a normal deceleration drive mode that decelerates the vehicle with normal braking force. Unlike a conventional internal combustion engine vehicle, in a vehicle using an electric motor, such as a fuel cell vehicle, the gear ratio is not changed by the driver's operation of the gear lever. Accordingly, shifting the gear lever to the braking position does not change the amount of drive torque, which corresponds to the amount by which the accelerator is depressed.The provision of the braking position in a gearshift device and the requirement for the driver to operate the gearshift device can thus create confusion. Accordingly, there is a need to relieve the driver of the need to change the drive mode between a deceleration augmentation drive mode with additional braking force and a normal deceleration drive mode in which the vehicle is decelerated using only the normal braking force and no additional braking force.

[0006] In addition, DE 10 2010 004 846 A1 discloses a method for recuperation for an electric vehicle, wherein the electric vehicle comprises an electric motor for driving the electric vehicle and an energy storage device for supplying the electric motor with electrical energy, and wherein the electric vehicle comprises a first operating element for braking the electric vehicle, a second operating element for accelerating the electric vehicle and a third operating element for specifying a target recuperation torque, wherein in a recuperation mode of the electric vehicle, the recuperation is carried out automatically according to the specified target recuperation torque in order to brake the electric vehicle according to the target recuperation torque and to supply electrical energy corresponding to the target recuperation torque to the energy storage device via the electric motor operated as a generator.

[0007] Furthermore, DE 10 2011 101 543 A1 discloses a method and a device for controlling a braking power, in particular a drag torque, of an electric or hybrid vehicle with an electric machine operable in recuperation mode, comprising an evaluation and control unit by means of which a recuperation power can be determined that can currently be generated taking into account at least one parameter, wherein a difference between the currently generateable recuperation power and a recuperation power set by at least one first means or a predetermined recuperation power can be determined, wherein by means of the evaluation and control unit the electric machine can be controlled to generate the currently possible recuperation power and an electrically controllable service brake can be controlled to generate a braking power depending on the determined difference. SUMMARY

[0008] To solve at least part of the problems described above, the present invention can be implemented in any of the aspects described below.

[0009] The above object is achieved by the subject matter of claims 1 and 5. Advantageous developments of the invention are the subject matter of the subsequent dependent claims. (1) According to an illustrative aspect of the present disclosure, a vehicle is provided. The vehicle may include: a fuel cell configured to supplyto receive supply of a fuel gas and generate electric power; an electric motor configured to be driven by the electric power generated by the fuel cell; a mode selector configured to selectively set a drive mode of the vehicle, when the accelerator is not operated, between a normal mode and a deceleration boost mode that decelerates the vehicle with a deceleration force higher than the deceleration force in the normal mode; and a controller configured to perform regenerative control of the electric motor in the normal mode or deceleration control to generate the deceleration force in the deceleration boost mode to decelerate the vehicle in the drive mode selected by the mode selector.When, in the drive mode set to the deceleration enhancement mode, an accelerator adjustment amount based on a driver's depression of an accelerator becomes larger than a cancellation threshold, the controller may change the drive mode from the deceleration enhancement mode to the normal mode.

[0010] When the accelerator travel in the drive mode set to the deceleration enhancement mode becomes greater than the cancellation threshold, the vehicle of the above-mentioned aspect changes the drive mode from the deceleration enhancement mode, which provides deceleration with a deceleration force greater than that in the normal mode, to the normal mode. The driver's depression of the accelerator is not based on the driver's intention to change the drive mode from the deceleration enhancement mode to the normal mode, but rather on the driver's desire for acceleration. Accordingly, the vehicle of this aspect does not require any specific operation from the driver to return the drive mode from the deceleration enhancement mode to the normal mode, thus reducing the driver's workload.In the vehicle of this aspect, the increase in the accelerator travel to return the drive mode from the deceleration boost mode to the normal mode is due to the driver depressing the accelerator based on the driver's desire to accelerate. The deceleration force when the driver releases the accelerator after depressing the accelerator is reduced by changing the drive mode to the normal mode. This results in no significant deceleration of the vehicle when the driver releases the accelerator after significantly depressing the accelerator based on the driver's desire to accelerate. The vehicle of this aspect reduces the likelihood of the driver feeling strange. (2) In the vehicle of the above-mentioned aspect, the mode selector can change the set drive mode from the normal mode to the deceleration boost mode in response to the driver's specific operation. This allows the driver's intention to be clearly reflected when changing the drive mode to the deceleration boost mode, which provides deceleration with a large deceleration force. When changing the drive mode from the deceleration boost mode to the normal mode, this configuration does not require any specific operation from the driver, thereby reducing the driver's burden as described above. (3) In the vehicle of the above aspect, the cancellation threshold may take different values ​​when a vehicle speed is in a low speed range and a high speed range, and the cancellation threshold in the low speed range may be higher than the cancellation threshold in the high speed range. This configuration has the following advantages. Regardless of whether the vehicle speed is in the low speed range or the high speed range, the driver steps on the accelerator for acceleration. In the low speed range, the vehicle of this aspect does not return the deceleration drive mode from the deceleration boost mode to the normal mode, but maintains the deceleration boost mode unless the accelerator is significantly depressed.The vehicle generally repeats deceleration and acceleration in heavy traffic and is likely to operate in the low-speed range. While operating in heavy traffic in the low-speed range with repeated deceleration and acceleration, the vehicle reduces the frequency with which it returns the drive mode from the deceleration boost mode to the normal mode. Thus, the vehicle of this aspect performs deceleration control with a higher deceleration force in the deceleration boost mode based on the driver's repeated requests for deceleration and acceleration. (4) In the vehicle of the above aspect, the control device can generate the deceleration force in the deceleration boost mode by combining the regenerative control of the electric motor and the drive control of a brake device configured to mechanically brake wheel rotations. This facilitates the generation of the high deceleration force in the deceleration boost mode.

[0011] The invention can be implemented by any other aspects besides the vehicle of the above-mentioned aspects, for example, by a drive control device and a drive control method and a movable body equipped with a fuel cell system. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically showing the structure of a vehicle according to an embodiment of the invention; Fig. 2 is a diagram illustrating the concept of setting a deceleration drive mode with reference to a relationship between the vehicle speed and the adjustment amount of an accelerator; Fig. 3 is a flowchart showing a flow of mode change determination control for determining a change in the deceleration drive mode; Fig. 4 is a flowchart showing a flow of deceleration control in the specific deceleration drive mode; and Fig. 5 is a flowchart showing a flow of mode return determination control for determining a return from a deceleration enhancement mode to a normal mode; DESCRIPTION OF THE EMBODIMENTS

[0012] An embodiment of the invention will be described below with reference to the accompanying drawings. Fig. 1 is a diagram schematically showing the structure of a vehicle 10 according to an embodiment of the invention. The vehicle 10 includes a fuel cell 100, a control device 200, a secondary battery 130, auxiliary machinery 135, a distribution control device 140, a drive motor 150, a drive shaft 160, a transfer case 170, front wheels 180F, rear wheels 180R, front wheel brakes 190F, and rear wheel brakes 190R. The vehicle 10 of the embodiment is a front-wheel drive vehicle, so the driving force of the drive motor 150 is transmitted from the drive shaft 160 to the front wheels 180F, and more specifically, is distributed to the left and right front wheels 180F by the transfer case 170. The front wheel brakes 190F and the rear wheel brakes 190R are provided on the front wheels 180F and the rear wheels 180R, respectively, as hydraulically operated disc brakes and are controlled by the controller 200 to decelerate the vehicle 10.The left and right rear wheels 180R are driven wheels, suspended independently from each other on suspensions 191Rs and thus do not have a drive shaft 160. The left and right front wheels 180F are also suspended on suspensions, but they are not shown separately.

[0013] The fuel cell 100 is configured to receive supplies of fuel gas and oxidizer gas and generate electricity through an electrochemical reaction of the fuel with oxygen. The controller 200 calculates amounts of the respective gases supplied to the fuel cell 100 in response to an output demand corresponding to the extent to which the driver depresses an accelerator 20, and controls the operation of the fuel cell 100 and the secondary battery 130 based on this output demand. The vehicle 10 includes a fuel gas supply system and a fuel gas discharge system involved in supplying and discharging the fuel gas to and from the fuel cell 100, an oxidizer gas supply system and an oxidizer gas discharge system involved in supplying and discharging the oxidizer gas to and from the fuel cell 100, and a cooling water circulation system for cooling the fuel cell 100.However, these systems do not directly fall within the scope of the invention and are not specifically described herein. For example, a compressor included in the oxidizing gas supply system and a circulation pump included in the cooling water circulation system belong to the auxiliary machines 135 and are driven under the control of the controller 200.

[0014] The secondary battery 130 may be, for example, a nickel hydride battery or a lithium-ion battery and is configured to output electric power stored in the secondary battery 130 as drive power for driving the drive motor 150 and the auxiliary machinery 135 via the distribution controller 140. The secondary battery 130 may be directly charged with electric power generated by the fuel cell 100 and may also be charged with regenerative electric power generated by the drive motor 150 regenerating the kinetic energy of the vehicle 10 during deceleration of the vehicle 10, for example, when the driver depresses a brake pedal 22.The distribution controller 140 controls the distribution of the amount of electric power to be output from the fuel cell 100 to the drive motor 150, the amount of electric power to be output from the secondary battery 130 to the drive motor 150, and the amount of drive power to be output to each auxiliary machine 35. During deceleration of the vehicle 10, the distribution controller 140 charges the secondary battery 130 with regenerative electric power from the drive motor 150. The regeneration of electric power by the drive motor 150 and the distribution of electric power and battery charge by the distribution controller 140 are under the control of the controller 200.The distribution control device 140 includes, in addition to a DC-DC converter (not shown), a voltage reduction unit configured to adjust the voltage to be suitable for both the drive motor 150 and the auxiliary machines 135, and distributes the electrical power with the adjusted voltage to the drive motor 150 and the auxiliary machines 135.

[0015] The drive motor 150 is driven by electric power generated by the fuel cell 100 and received via the distribution controller 140, and serves as an electric motor for propelling the vehicle 10. During deceleration of the vehicle 10, the drive motor 150 serves as a generator to regenerate electrical energy from the kinetic energy of the vehicle 10 under the control of the controller 200. The drive shaft 160 is a rotary shaft configured to transmit the drive power generated by the drive motor 150 to the transfer case 170. The transfer case 170 distributes the drive power to the left and right front wheels 180F.

[0016] The control device 200 is implemented by a microcomputer having a CPU that performs logical operations, a ROM, and a RAM.The controller 200 receives inputs from, for example, an accelerator position sensor configured to detect the extent to which the accelerator 20 is depressed, a brake sensor configured to detect the extent to which the brake pedal 22 is depressed, a vehicle speed sensor (not shown), and a deceleration drive mode change switch 30, and performs various controls of the vehicle 10, including drive control of an injector (not shown) involved in gas supply and discharge, drive control of various valves provided to control the supply and discharge of the fuel gas, and the like, regenerative control of the drive motor 150, and drive control of the front wheel brakes 190F and the rear wheel brakes 190R.According to this embodiment, the deceleration drive mode change switch 30 is provided as a push-button switch arranged on an instrument panel or a steering wheel of the vehicle 10. The deceleration drive mode change switch 30 is configured to be set and reset by the driver's operation and also to be automatically reset by the controller 200, as described below. This deceleration drive mode change switch 30 may be provided in a gear change device. In this case, the gear change device, like the push-button switch described above, is configured to automatically return the gear position to the drive position using a solenoid or the like after the driver moves a gear lever from the drive position to the brake position.

[0017] The following describes a deceleration drive mode change control performed in the vehicle 10 of the embodiment. The vehicle 10 of the embodiment can travel in one of two deceleration drive modes in response to the operation of the deceleration drive mode change switch 30. A first deceleration drive mode (hereinafter referred to as normal mode) is a deceleration drive mode that is applied while the vehicle 10 is traveling without the driver operating the deceleration drive mode change switch 30. In the normal mode, the deceleration force required to decelerate the vehicle 10 in response to the depression of the Fig. 1) is covered by the regenerative braking force obtained through regenerative control of the drive motor 150 by the controller 200. A second deceleration drive mode (hereinafter referred to as the deceleration boost mode) is a deceleration drive mode that is performed when a predetermined condition described below is met after the driver operates the deceleration drive mode change switch 30. In the deceleration boost mode, a predetermined braking force is applied to the drive shaft 160 when the driver releases the accelerator 20. The predetermined braking force corresponds to the braking force of the engine brake in an internal combustion engine vehicle.This braking is applied when the accelerator 20 is released and is thus referred to as accelerator-off braking or accelerator-off vehicle deceleration. The accelerator-off deceleration force is obtained through the regenerative control of the drive motor 150 by the controller 200. When the driver steps on the brake pedal 22 in this state, the braking force is amplified by the regenerative control. In response to an increase in the amount of depressing the brake pedal 22, the front wheel brakes 190F and the rear wheel brakes 190R are applied and controlled to decelerate the vehicle 10 with a braking force greater than the braking force in the normal mode.After the deceleration drive mode is changed to the deceleration boost mode by the driver's operation of the deceleration drive mode change switch 30, the deceleration drive mode is returned from the deceleration boost mode to the normal mode upon satisfaction of a predetermined condition described below. The deceleration drive mode switch 30 is reset to OFF upon satisfaction of a specified condition. Fig. 2 is a diagram illustrating the concept of setting the deceleration drive mode with reference to the relationship between the vehicle speed and the adjustment amount of the accelerator 20.

[0018] As in Fig. As shown in Fig. 2, in the vehicle 10 of the embodiment, a first threshold value As1 and a second threshold value As2 are defined by the relationship between the vehicle speed and the adjustment amount of the accelerator 20. The first threshold value As1 is set to a constant accelerator adjustment amount regardless of the vehicle speed. The second threshold value As2 is set to different profiles in a low-speed range with the vehicle speed of 50 km / h or less and in a high-speed range with the vehicle speed exceeding 50 km / h. The second threshold value As2 in the low-speed range is set to be higher than the value of the second threshold value As2 in the high-speed range and to become higher as the vehicle speed decreases.The controller 200 changes the deceleration drive mode as described above based on the threshold values ​​As1 and As2 and an actual accelerator travel As during driving.

[0019] When the vehicle 10 is traveling while and after the driver operates the deceleration drive mode change switch 30, the controller 200 activates the deceleration enhancement mode in response to the driver's release of the accelerator 20 in the state that the accelerator travel amount As based on the driver's depression of the accelerator 20 is in a region C that is below the second threshold As2. When the accelerator travel amount As based on the driver's depression of the accelerator 20 is in a region A that is not below the first threshold As1, the controller 200 does not accept the ON operation of the deceleration drive mode change switch 30 but performs braking force control in the normal mode.When the accelerator stroke As, based on the driver's depression of the accelerator 20 after the operation of the deceleration drive mode change switch 30, is in a region B that is not lower than the second threshold As2 and that is lower than the first threshold As1, the controller 200 suspends the braking force control in the deceleration boost mode despite the driver's operation of the deceleration drive mode change switch 30. Suspending the braking force control in the deceleration boost mode includes the following processing sequence. When the accelerator stroke As increases from the region C to the region B after the driver's operation of the deceleration drive mode change switch 30, the controller 200 returns the deceleration drive mode from the deceleration boost mode to the normal mode.In this state, the controller 200 does not cancel the deceleration boost mode, but suspends the deceleration boost mode. When the accelerator travel distance As increases from region B to region C during braking force control in the normal mode, the controller 200 returns the deceleration drive mode to the deceleration boost mode and performs braking force control in the deceleration boost mode. On the other hand, when the accelerator travel distance As increases from region B to region A after the driver operates the deceleration drive mode change switch 30, the controller cancels the suspended deceleration boost mode and resets the deceleration drive mode change switch 30.Even when the accelerator travel As decreases into the region C, the controller 200 does not perform braking force control in the deceleration boost mode, but performs regenerative control of the drive motor 150 in the normal mode. Such control of the vehicle's braking force is implemented through a sequence of deceleration drive mode change control performed by the controller 200, as described below.

[0020] Fig. 3 is a flowchart showing a flow of mode change determination control for determining a change in the deceleration drive mode. Fig. 4 is a flowchart showing a flow of deceleration control in the specific deceleration drive mode. Fig. 5 is a flowchart showing a flow of mode return determination control for determining a return from the deceleration enhancement mode to the normal mode. The mode change determination control of Fig. 3, the deceleration control of Fig. 4 and the mode return determination control of Fig. 5 are repeatedly executed by the control device 200 at predetermined time intervals after an ON operation of an ignition switch (not shown) in the vehicle 10. When the times for executing the respective controls are the same, the mode change determination control, the accelerator-off deceleration control, and the mode return determination control are preferably executed in this order.

[0021] In the mode change determination control of Fig. 3, the controller 200 first determines whether the driver turns the deceleration drive mode change switch 30 on (step S100). In response to a negative answer, the controller 200 resets a deceleration boost mode flag Fb to a value of 0 (step S105). The deceleration boost mode flag Fb is set to a value of 1 in response to an ON operation of the deceleration drive mode change switch 30 by the driver who needs the deceleration boost mode to decelerate the vehicle with the deceleration force higher than the deceleration force for decelerating the vehicle in the normal mode. Thus, setting of the deceleration enhancement mode flag Fb indicates the state in which deceleration control is to be performed in the deceleration enhancement mode to decelerate the vehicle with the deceleration force higher than the deceleration force in the normal mode.Resetting the deceleration boost mode flag Fb indicates the state that deceleration control is to be performed in the normal mode. The braking force actually applied to the drive shaft 160 and the front and rear wheels 180F and 180R depends on the travel amount of the accelerator 20 and the extent to which the brake pedal 22 was depressed before the braking force was controlled. Deceleration control in the normal mode or the deceleration boost mode follows the deceleration control flow described below. Fig. 4). Following the negative answer in step S100, the controller 200 resets the deceleration enhancement mode flag Fb to the value 0 in step S105 to concentrate on the processing of step S110 and the following in a subsequent cycle of this routine and the deceleration control of Fig. 4, and terminates this routine. If the deceleration drive mode change switch 30 is ON, the controller 200 resets the deceleration drive mode change switch 30 along with resetting the deceleration boost mode flag Fb in step S105. This will be described in detail below.

[0022] If it is determined in step S100 that the driver turns on the deceleration drive mode change switch 30, that is, in response to an affirmative answer, the control device 200 inputs vehicle information, including the vehicle speed V and the accelerator travel distance As, which represents the extent to which the driver depresses the accelerator 20 (step S110). The control device 200 then compares the inputted accelerator travel distance As with the Fig. 2 (step S120). If it is determined in step S120 that the input accelerator travel As is at or above the first threshold As1, that is, in response to an affirmative answer, the controller 200 proceeds to step S105 to reset the deceleration boost mode flag Fb to the value 0 and terminates this routine. In this case, following the affirmative answer in step S120, the deceleration boost mode flag Fb is reset to the value 0 in step S105. The accelerator travel As is in the region A shown in Fig. 2, so that the driver's operation of the deceleration drive mode change switch 30 is not accepted or canceled. This indicates the state that the deceleration drive mode is not to be changed to the deceleration boost mode for decelerating the vehicle with the deceleration force higher than the normal mode, but the vehicle is to be decelerated in the normal mode. In this case, the deceleration drive mode change switch 30 is returned to OFF as described above. As described above, despite the driver's ON operation of the deceleration drive mode change switch 30, when the accelerator stroke As increases to the region A.In this case, the deceleration boost mode flag Fb is not set to 1 even if the accelerator stroke As, which represents the amount by which the driver depresses the accelerator 20, decreases to the region B or the region C. Thus, the controller 200 does not perform braking force control in the deceleration boost mode until the next ON operation of the deceleration drive mode change switch 30 by the driver.

[0023] In response to a negative answer in step S120 (As< As1), the control device 200 compares in the next step S130 the accelerator adjustment path As shown in step S110 with the value shown in Fig. 2 shown second threshold value As2.

[0024] If it is determined in step S130 that the input accelerator travel As is smaller than the second threshold value As2, that is, in response to an affirmative answer, the controller 200 sets the deceleration boost mode flag Fb to the value 1 (step S140) and terminates this routine. In this case, the deceleration boost mode flag Fb is reset to the value 1 in step S140 following the affirmative answer in step S130. The accelerator travel As lies in the region C shown in Fig. 2, so that the driver's operation of the deceleration drive mode change switch 30 is accepted. This indicates the state that the deceleration drive mode is to be changed from the normal mode to the deceleration boost mode for decelerating the vehicle with a deceleration force higher than in the normal mode, and the vehicle is to be decelerated in the deceleration boost mode.

[0025] If, however, it is determined in step S130 that the inputted accelerator travel As is at least as large as the second threshold value As2, ie, in response to a negative answer, the control device 200 terminates this routine without further processing. The negative answer in step S130 following the negative answer in step S120 indicates that the accelerator travel As is in the range determined in Fig. 2. In the case of a negative answer in step S130, the deceleration enhancement mode flag Fb, which has been set or reset in a previous cycle of this mode change determination control routine, is kept unchanged. For example, in the case where the deceleration enhancement mode has been activated in response to the driver's operation of the deceleration drive mode change switch 30, the activation is not canceled but maintained. If the accelerator travel As is in the range shown in Fig. 2, the deceleration enhancement mode flag Fb is set by the Fig. 5 shown mode return determination control is reset.

[0026] In the following, the deceleration control of the vehicle 10 will be described with reference to Fig. 4. In the deceleration control of Fig. 4, the controller 200 first inputs vehicle information, including the vehicle speed V and the accelerator travel distance As, which represents the amount by which the driver depresses the accelerator 20, and stores the inputted accelerator travel distance As in a specific memory region (step S210). According to this embodiment, the currently inputted accelerator travel distance As and the previously inputted accelerator travel distance As are stored in the specific memory region. The controller 200 calculates an amount Asb by which the accelerator travel distance is decreased based on a change in the stored accelerator travel distance As and stores the newly calculated amount Asb by which the accelerator travel distance is decreased in a specific memory region (step S215). The purpose is to check the travel distance of the accelerator 20.

[0027] The controller 200 then determines whether the driver has fully released the accelerator 20 and is not stepping on the accelerator based on the calculated amount Asb by which the accelerator travel is reduced (step S220). If it is determined in step S220 that the driver has not fully released the accelerator 20, the controller 200 terminates this routine without the need for further deceleration control of the vehicle 10.

[0028] On the other hand, if it is determined in step S220 that the driver has completely released the accelerator 20, that is, in the case of an affirmative answer, the control device 200 reads in the above-described mode change determination control from Fig. 3 set or reset deceleration boost mode flag Fb and determines whether the deceleration boost mode flag Fb is 0 (step S230). As described above, the deceleration boost mode flag Fb is set (Fb=1) when the accelerator travel As after the driver turns on the deceleration drive mode change switch 30 is in the range shown in Fig. 2. The deceleration boost mode flag Fb is reset (Fb=0) when the deceleration drive mode change switch 30 is not turned on by the driver or when the accelerator travel As is in the range shown in Fig. Region A shown in Figure 2 rises. The resetting of the deceleration boost mode flag Fb indicates the state that deceleration control in the normal mode is to be performed. In response to an affirmative answer (Fb=0) in step S230, the controller 200 executes deceleration control in the normal mode (step S240). The deceleration control in the normal mode does not apply braking without the driver depressing the brake pedal 22. In response to the driver depressing the brake pedal 22, the deceleration control in the normal mode performs regenerative control of the drive motor 150 with the rotation of the front wheels 180F based on the amount by which the driver depresses the brake pedal 22, and applies the regenerative braking force obtained by the regenerative control of the drive motor 50 to the drive shaft 160 to decelerate the vehicle 10.During normal mode deceleration control, the controller 200 may use the regenerative electric power obtained through the regenerative control of the drive motor 150 to charge the secondary battery 130 or as drive power for the auxiliary machines 135, such as the compressor in the oxidizing gas supply system and the circulation pump in the cooling water circulation system. During such regenerative electric power consumption, the controller 200 performs normal mode braking force control in step S240 to decelerate the vehicle 10 using the regenerative braking force of the drive motor 150 as the deceleration force.During deceleration control of the vehicle 10 in the normal mode, the controller 200 calculates a deceleration force corresponding to the amount by which the driver depresses the brake pedal 22 in response to the driver's depression of the brake pedal 22, and performs regenerative control of the drive motor 150 to obtain the calculated deceleration force.

[0029] In response to a negative answer (Fb=1) in step S230, however, the controller 200 executes deceleration control in the deceleration boost mode (step S250). Like engine braking in an internal combustion engine vehicle, the deceleration control in the deceleration boost mode applies the braking force obtained by the regenerative control of the drive motor 150 to the drive shaft 160 without the driver depressing the brake pedal 22. When the driver steps on the brake pedal 22, the controller 200 activates the drive control of the front wheel brakes 190F and the rear wheel brakes 190R in addition to the braking force by the regenerative control, to decelerate the vehicle 10 with the deceleration force higher than in the normal mode.In the case where the high regenerative braking force can be obtained by consuming the regenerative electric power of the drive mode 150, for example, when the secondary battery 130 has a state of charge substantially equal to zero and a sufficient amount of regenerative electric power is consumed to charge the secondary battery 130, or when the auxiliary machines 135 consume a sufficient amount of electric power, the controller 200 enables the regenerative braking force of the drive motor 150 to cover the deceleration force higher than the deceleration force in the normal mode.When the driver steps on the brake pedal 22, the control device 200 covers the deceleration force corresponding to the amount by which the driver depresses the brake pedal 22 with the mechanical braking force obtained by the drive control of the front wheel brakes 190F and the rear wheel brakes 190R, in addition to the regenerative braking force of the drive motor 150, to decelerate the vehicle 10 with the deceleration force higher than the deceleration force in the normal mode. The control device 200 may cover the deceleration force higher than the deceleration force in the normal mode only with the mechanical braking force obtained by the drive control of the front wheel brakes 190F and the rear wheel brakes 190R to decelerate the vehicle 10.As in the deceleration control in the normal mode, during the deceleration of the vehicle 10 in the deceleration enhancement mode, the controller 200 calculates the deceleration force corresponding to the amount by which the driver depresses the brake pedal 22, and performs regenerative control of the drive motor 150 in combination with the drive control of the front wheel brakes 190F and the rear wheel brakes 190R to obtain the deceleration force higher than the calculated deceleration force, for example, the deceleration force increased by 10% to 20% compared to the deceleration force in the normal mode.

[0030] The following describes the process of returning the deceleration drive mode from the deceleration boost mode with reference to Fig. 5. In the mode return determination control of Fig. 5, the control device 200 reads the in the above-described mode change determination control of Fig. 3 and determines whether the current deceleration drive mode is the deceleration enhancement mode (step S300). In response to a negative answer (Fb = 0), the controller 200 determines that the current deceleration drive mode is the normal mode and exits this routine without further processing.

[0031] In response to an affirmative answer (Fb=1) in step S300, the controller 200 inputs vehicle information, including the vehicle speed V and the accelerator travel As, which represents the extent to which the driver depresses the accelerator 20 (step S310). The controller 200 then compares the input accelerator travel As with the Fig. 2 (step S320). If, however, it is determined in step S320 that the accelerator travel As is below the second threshold As2, ie, in response to a negative answer, the control device 200 terminates this routine without further processing. In the case of the negative answer in step S320 following the positive answer (Fb=1) in step S300, the deceleration boost mode flag Fb is kept at the value 1 after the negative answer in step S320. The deceleration boost mode flag Fb is set in the mode change determination control of Fig. 3 is set to the value 1 if the accelerator travel As is in the range Fig. 2, which is below the second threshold value As2 (steps S130 and S140). The negative answer in step S320 following the positive answer (Fb=1) in step S300 indicates that the accelerator travel As is maintained in the region C. This indicates a continuation of the deceleration control of the vehicle 10 in the deceleration enhancement mode.

[0032] Following an affirmative answer (As ≥ As2) in step S320, the controller 200 resets the deceleration enhancement mode flag Fb to the value 0 (step S330) and terminates this routine. As described above, the deceleration enhancement mode flag Fb is reset in the mode change determination control of Fig. 3 is set to the value 1 if the accelerator travel As is in the range Fig. 2, which is below the second threshold value As2 (steps S130 and S140). Thus, the affirmative answer in step S320 following the affirmative answer (Fb = 1) in step S300 indicates that the accelerator travel As increases from region C to region B. The deceleration enhancement mode flag Fb is reset to the value 0 in step S330 following the affirmative answer (As ≥ As2) in step S320. In this case, the accelerator travel As increases to or above the second threshold value As2 based on the amount by which the driver depresses the accelerator 20 after the deceleration enhancement mode flag Fb is set to the value 1, so that the deceleration drive mode with the accelerator not being operated is changed from the deceleration enhancement mode to the normal mode (step S240 in Fig. 4).

[0033] As described above, in response to the driver's operation of the deceleration drive mode change switch 30, the vehicle 10 of the embodiment selectively changes the deceleration drive mode with the accelerator off according to the accelerator travel amount As between the normal mode that uses the regenerative braking force obtained by the regenerative control of the drive motor 150 as the deceleration force (step S240 in Fig. 4) and the deceleration enhancement mode, which decelerates the vehicle 10 with the deceleration force that is higher than in the normal mode (step S250 in Fig. 4). When the driver releases the accelerator 20 in the state where the accelerator travel As is in the region C, which is below the second threshold As2, the vehicle 10 of the embodiment performs deceleration control in the deceleration boost mode with the deceleration force that is higher than that in the normal mode. When the accelerator travel As increases to or above the second threshold after changing from the deceleration drive mode to the deceleration boost mode, the vehicle 10 of the embodiment returns the deceleration drive mode from the deceleration boost mode to the normal mode (steps S320 and S330 in Fig. 5). The driver's depression of the accelerator 20, which increases the accelerator travel As from the region C to or above the second threshold As2, is not based on the driver's desire to return the deceleration drive mode from the deceleration enhancement mode to the normal mode, but rather on the driver's desire to accelerate. The vehicle 10 of the embodiment does not require any specific driver operation, such as resetting the deceleration drive mode change switch 30, to return the deceleration drive mode from the deceleration enhancement mode to the normal mode. This reduces the driver's workload.In the vehicle 10 of the embodiment, the increase in the accelerator travel As for returning the deceleration drive mode from the deceleration enhancement mode to the normal mode is due to the driver depressing the accelerator 20 based on the driver's desire to accelerate. The deceleration force when the driver releases the accelerator 20 after depressing the accelerator 20 is reduced by returning the deceleration drive mode to the normal mode. This results in insignificant deceleration of the vehicle, similar to engine braking in an internal combustion engine vehicle, when the driver releases the accelerator 20 after significantly depressing the accelerator 20 based on the driver's desire to accelerate.The vehicle 10 of this aspect thus reduces the likelihood of the driver feeling strange or confused.

[0034] In the vehicle 10 of the embodiment, the second threshold value As2 used to determine whether to return the deceleration drive mode from the deceleration enhancement mode to the normal mode is set to different profiles in the low speed range with the vehicle speed not exceeding 50 km / h and in the high speed range with the vehicle speed exceeding 50 km / h, respectively, as shown in Fig. 2. The second threshold value As2 in the low speed range is set to be higher than the value of the second threshold value As2 in the high speed range and to become higher as the vehicle speed decreases. This has the following advantages. Regardless of whether the vehicle speed is in the low speed range or the high speed range, the driver steps on the accelerator 20 to achieve acceleration. In the low speed range, the vehicle 10 of the embodiment does not return the deceleration drive mode from the deceleration boost mode to the normal mode, but maintains the deceleration boost mode until the accelerator travel amount As2 increases to or above the second threshold value As2 in response to a significant depression of the accelerator 20 by the driver (negative answer in step S320 in Fig. 5). The vehicle generally repeats deceleration and acceleration in heavy traffic and is likely to run in the low-speed range. While the vehicle 10 runs in heavy traffic in the low-speed range with repeated deceleration and acceleration, the vehicle 10 of this embodiment reduces the frequency with which it returns the deceleration drive mode from the deceleration boost mode to the normal mode. Thus, the vehicle 10 of this embodiment performs deceleration control with the higher deceleration force in the deceleration boost mode based on the driver's repeated deceleration and acceleration requests.

[0035] When the driver steps on the brake pedal 22, the vehicle 10 of the embodiment uses both regenerative control of the drive motor 150 and drive control of the front wheel brakes 190F and the rear wheel brakes 190R to generate a deceleration force that is higher in the deceleration boost mode than the deceleration force in the normal mode. Thus, the vehicle 10 of this embodiment can generate a deceleration force that is higher in the deceleration boost mode than the deceleration force in the normal mode.

[0036] When the accelerator travel As based on the driver's depression of the accelerator 20 is at least as large as the first threshold As1, the vehicle 10 of the embodiment continues the deceleration control in the normal mode with the deceleration force lower than that in the deceleration enhancement mode, even though the driver operates the deceleration drive mode change switch 30 ( Fig. 2 and positive answer in step S120 in Fig. 3). If the deceleration enhancement mode flag Fb has not previously been set to the value 1, the vehicle 10 of the embodiment, in addition to resetting the deceleration enhancement mode flag Fb to the value 0, returns the deceleration drive mode change switch 30 to OFF. The accelerator travel distance As, which is at least as large as the first threshold value As1, is due to the driver's pronounced depression of the accelerator 20 based on the driver's desire for acceleration. Accordingly, the deceleration force with the accelerator not operated after the deceleration of the accelerator 20 is the low deceleration force in the normal mode. Even if the accelerator travel distance As is set to the value shown in Fig. 2, the vehicle 10 of the embodiment does not perform deceleration control in the deceleration enhancement mode. This results in no significant deceleration of the vehicle when the driver releases the accelerator 20 after significantly depressing the accelerator 20 based on the driver's desire to accelerate. The vehicle 10 of this aspect thus reduces the likelihood of the driver feeling strange or confused.

[0037] The above embodiment describes the front-wheel drive vehicle configured to transmit the driving force of the drive motor 150 to the front wheels 180F. However, the invention is not limited to the vehicle of this configuration, but is also applicable to a rear-wheel drive vehicle configured to transmit the driving force of the drive motor 150 to the rear wheels 180R, or to a four-wheel drive vehicle in which the drive motor 150, the drive shaft 160, and the transfer case 170 are provided at both the front wheels and the rear wheels.

[0038] In the above-described embodiment, the deceleration drive mode is changed from the normal mode to the deceleration enhancement mode in response to the driver's operation of the deceleration drive mode change switch 30. However, this configuration is not limiting. When the vehicle travels downhill for a long time, the vehicle speed increases in response to the driver's slight depression of the accelerator 20 or even without the driver's depression of the accelerator 20. A modification may involve increasing a profile of the vehicle speed and increasing a profile of the amount by which the accelerator 20 is depressed (the accelerator travel amount As) to detect when the vehicle travels downhill for a long time, and may change the deceleration drive mode from the normal mode to the deceleration enhancement mode without the driver's operation of the deceleration drive mode change switch 30.The modification can return the deceleration drive mode from the deceleration boost mode to the normal mode based on the relationship between the accelerator stroke As and the vehicle speed V, as in the above-described embodiment. This further reduces the burden on the driver. According to another modification, the accelerator 20 can be equipped with a switch configured to detect when the accelerator 20 is not depressed. This modification can eliminate the steps of reading the vehicle information and calculating the amount Asb by which the accelerator stroke is reduced. Fig. 4 allow.

[0039] In each embodiment and modification, some or all of the functions or processes implemented by software may be implemented by hardware. Some or all of the functions or processes implemented by hardware may be implemented by software. The hardware may be any circuitry, such as an integrated circuit, a discrete circuit, or a circuit module or combination of these circuits.

Claims

[1] Vehicle (10), comprising: a fuel cell (100) configured to receive a supply of fuel gas and generate electrical power; an electric motor (150) designed to be driven by the electrical power generated by the fuel cell (100); a mode selector (30) configured to selectively set a drive mode of the vehicle (10) when the accelerator (20) is not actuated between a normal mode, which decelerates the vehicle with a deceleration force necessary to decelerate the vehicle (10) in response to the driver depressing a brake pedal (22), covered by a regenerative braking force obtained by regenerative control of the electric motor (150), and a deceleration boost mode, which decelerates the vehicle (10) in response to the driver releasing the accelerator (20) with a deceleration force that is higher than the deceleration force in the normal mode; and a control device (200) configured to perform the regenerative control of the electric motor (150) in the normal mode or to perform a deceleration control in the deceleration boost mode in which the deceleration force is generated to decelerate the vehicle (10) in the drive mode set by the mode selector (30), wherein the control device (200) changes the drive mode from the deceleration enhancement mode to the normal mode when, in the drive mode set to the deceleration enhancement mode, an accelerator adjustment amount based on a depression of the accelerator (20) by the driver becomes higher than a cancellation threshold value (As1, As2). [2] The vehicle (10) of claim 1, wherein the mode selector (30) changes the set drive mode from the normal mode to the deceleration enhancement mode in response to the determined driver operation. [3] The vehicle (10) according to claim 1 or 2, wherein the cancellation threshold value (As2) takes different values when a vehicle speed is in a low speed range or a high speed range, and the cancellation threshold value in the low speed range is higher than the cancellation threshold value in the high speed range. [4] The vehicle (10) according to any one of claims 1 to 3, wherein the control device (200) generates the deceleration force in the deceleration boost mode by combining the regenerative control of the electric motor (150) and the drive control of a braking device (190R, 190F) configured to mechanically brake rotations of the wheels (180R, 180F). [5] A control method for a vehicle (10), the vehicle (10) comprising a fuel cell (100) configured to receive a supply of a fuel gas and generate electrical power, and an electric motor (150) configured to be driven by the electrical power generated by the fuel cell (100), the control method comprising: selectively setting a drive mode of the vehicle (10) when the accelerator (20) is not actuated between a normal mode, which decelerates the vehicle with a deceleration force necessary to decelerate the vehicle (10) in response to the driver depressing a brake pedal (22), covered by a regenerative braking force obtained by regenerative control of the electric motor (150), and a deceleration boost mode, which decelerates the vehicle (10) in response to the driver releasing the accelerator (20) with a deceleration force that is higher than the deceleration force in the normal mode; Performing regenerative control of the electric motor (150) in the normal mode or performing deceleration control in which a deceleration force is generated in the deceleration boost mode to decelerate the vehicle (10) in the drive mode set by the mode selector (30); and Changing the drive mode from the deceleration enhancement mode to the normal mode when, in the drive mode set to the deceleration enhancement mode, an accelerator adjustment amount based on the driver's depression of the accelerator (20) becomes larger than a cancellation threshold value (As1, As2). [6] A control method for the vehicle (10) according to claim 5, wherein setting the drive mode comprises changing the set drive mode from the normal mode to the deceleration enhancement mode in response to the determined operation by the driver. [7] A control method for the vehicle (10) according to claim 5 or 6, wherein the cancellation threshold value (As2) takes different values when a vehicle speed is in a low speed range or a high speed range, and the cancellation threshold value in the low speed range is higher than the cancellation threshold value in the high speed range. [8] A control method for the vehicle (10) according to any one of claims 5 to 7, wherein performing the deceleration control comprises generating the deceleration force in the deceleration boost mode by combining the regenerative control of the electric motor (150) and the drive control of a brake device (190R, 190F) configured to mechanically brake rotations of the wheels (180R, 180F).

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