Patent Application
20070267915
One mode of carrying out the invention is described below as a preferred embodiment.
The engine 22 is an internal combustion engine that consumes a hydrocarbon fuel, such as gasoline or light oil, to output the power. A crankshaft 23 as an output shaft of the engine 22 is linked to the torque converter 30. The crankshaft 23 is also connected with a starter motor 26 via a gear train 25 and with an alternator 28 and a mechanical oil pump 29 via a belt 27. The engine 22 is driven and operated under control of an engine electronic control unit (hereafter referred to as ‘engine ECU’) 24. The engine ECU 24 receives input signals from various sensors measuring and detecting the operation conditions of the engine 22, for example, a crank position signal from a crank position sensor 23a attached to the crankshaft 23. The engine ECU 24 regulates the amount of fuel injection and the amount of intake air and adjusts the ignition timing, in response to these input signals. The engine ECU 24 makes communication with the hybrid ECU 70 to control the operation of the engine 22 in response to control signals from the hybrid ECU 70 and to output data regarding the operating conditions of the engine 22 to the hybrid ECU 70 according to the requirements.
The torque converter 30 of this embodiment is a known fluid torque converter and is equipped with a hydraulic pressure lockup clutch. The forward-backward drive switchover mechanism 35 includes a double-pinion planetary gear mechanism 36, a brake B1, and a clutch C1. In the forward-backward drive switchover mechanism 35, in the off position of the brake B1 and the on position of the clutch C1, the rotation of the output shaft 34 of the torque converter 30 is directly transmitted to the input shaft 41 of the CVT 40 to move the hybrid vehicle 20 forward. In the on position of the brake B1 and the off position of the clutch C1, the rotation of the output shaft 34 of the torque converter 30 is inverted to the reverse direction and is transmitted to the input shaft 41 of the CVT 40 to move the hybrid vehicle 20 backward. In the off positions of both the brake B1 and the clutch C1, the output shaft 34 of the torque converter 30 is decoupled from the input shaft 41 of the CVT 40.
The CVT 40 includes a primary pulley 43 of variable groove width linked to the input shaft 41, a secondary pulley 44 of variable groove width linked to an output shaft 42 or a driveshaft, and a belt 45 set in the grooves of the primary pulley 43 and the secondary pulley 44. The groove widths of the primary pulley 43 and the secondary pulley 44 are varied by means of the hydraulic pressure of the hydraulic oil applied by a hydraulic circuit 47 under operation control of a CVT electronic control unit (hereafter referred to as CVTECU) 46. Varying the groove widths enables the input power of the input shaft 41 to go through the continuously variable speed change and to be output to the output shaft 42. The hydraulic circuit 47 regulates the hydraulic pressure and the flow rate of the hydraulic oil fed by an electric oil pump 60 and by the mechanical oil pump 29 and supplies the hydraulic oil of the regulated hydraulic pressure and flow rate to the primary pulley 43, the secondary pulley 44, the torque converter 30 (lockup clutch), the brake B1, and the clutch C1. The CVTECU 46 inputs a rotation speed Nin of the input shaft 41 and a rotation speed Nout of the output shaft 42. The CVTECU 46 generates and outputs driving signals to the hydraulic circuit 47, in response to these input data. The CVTECU 46 also controls on and off the brake B1 and the clutch C1 of the forward-backward drive switchover mechanism 35 and performs the lockup control of the torque converter 30. The CVTECU 46 makes communication with the hybrid ECU 70 to regulate the change gear ratio of the CVT 40 in response to control signals from the hybrid ECU 70 and to output data regarding the operating conditions of the CVT 40 to the hybrid ECU 70 according to the requirements.
The motor 50 is constructed as a known synchronous motor generator that may be actuated both as a generator and as a motor. The motor 50 is connected with the alternator 28, which is driven by the engine 22, via an inverter 52 and with a high-voltage battery 55 (for example, a secondary battery having a rated voltage of 42 V) having its output terminal linked to a power line from the alternator 28. The motor 50 is accordingly driven with electric power supplied from the alternator 28 or from the high-voltage battery 55 and generates regenerative electric power during deceleration to charge the high-voltage battery 55. The motor 50 is driven and operated under control of a motor electronic control unit (hereafter referred to as ‘motor ECU’) 53. The motor ECU 53 receives input signals required for the operation control of the motor 50, for example, signals from a rotational position detection sensor 50a that detects the rotational position of a rotor in the motor 50 and values of phase current for the motor 50 from a current sensor (not shown). The motor ECU 53 generates and outputs switching signals to switching elements included in the inverter 52, in response to these input signals. The motor ECU 53 makes communication with the hybrid ECU 70 to output switching control signals to the inverter 52 for the operation control of the motor 50 in response to control signals from the hybrid ECU 70 and to output data regarding the operating conditions of the motor 50 to the hybrid ECU 70 according to the requirements. The high-voltage battery 55 is connected with a low-voltage battery 57 via a DC-DC converter 56 having the function of voltage conversion. The electric power supplied from the high-voltage battery 55 goes through the voltage conversion by the DC-DC converter 56 and is transmitted to the low-voltage battery 57. The low-voltage battery 57 is used as the power source of various auxiliary machines including the electric oil pump 60. Both the high-voltage battery 55 and the low-voltage battery 57 are under management and control of a battery electronic control unit (hereafter referred to as ‘battery ECU’) 58. The battery ECU 58 computes remaining charge levels or states of charge (SOC) and input and output limits of the high-voltage battery 55 and the low-voltage battery 57, based on inter-terminal voltages from voltage sensors (not shown) attached to the respective output terminals (not shown) of the high-voltage battery 55 and the low-voltage battery 57, charge-discharge electric currents from current sensors (not shown), and battery temperatures from temperature sensors (not shown). The battery ECU 58 makes communication with the hybrid ECU 70 to output data regarding the conditions of the high-voltage battery 55 and the low-voltage battery 57, for example, their states of charge (SOC), to the hybrid ECU 70 according to the requirements.
The HBS 100 mounted on the hybrid vehicle 20 has a so-called tandem master cylinder 101, a brake actuator 102, and wheel cylinders 109a through 109d respectively provided for the front wheels 65a and 65b and the rear wheels 65c and 65d. The HBS 100 supplies a master cylinder pressure Pmc to the wheel cylinders 109a through 109d for the front wheels 65a and 65b and the rear wheels 65c and 65d via the brake actuator 102, so as to apply master cylinder pressure Pmc-based braking force to the front wheels 65a and 65b and the rear wheels 65c and 65d. The master cylinder pressure Pmc is generated by the master cylinder 101 as an operation pressure in response to the driver's depression of a brake pedal 85. In the HBS 100 of this embodiment, the master cylinder 101 is provided with a brake booster 103 that utilizes a negative pressure Pn produced by the engine 22 to assist the driver's braking operation. As shown in
The brake actuator 102 is actuated by the low-voltage battery 57 as the power source. The brake actuator 102 regulates the master cylinder pressure Pmc generated by the master cylinder 101 and supplies the regulated master cylinder pressure Pmc to the wheel cylinders 109a through 109d, while adjusting the hydraulic pressure in the wheel cylinders 109a through 109d to ensure application of braking force to the front wheels 65a and 65b and the rear wheels 65c and 65d regardless of the driver's pressing force of the brake pedal 85.
The first system 110 includes a master cylinder cut solenoid valve (hereafter referred to as ‘MC cut solenoid valve’) 111 connected with the master cylinder 101 via an oil supply path L10, and holding solenoid valves 112a and 112d linked to the MC cut solenoid valve 111 via an oil supply path L11 and respectively connected with the wheel cylinder 109a for the right front wheel 65a and with the wheel cylinder 109d for the left rear wheel 65d via pressure-varying oil paths L12a and L12d. The first system 110 also includes pressure reduction solenoid valves 113a and 113d respectively connected with the wheel cylinder 109a for the right front wheel 65a and with the wheel cylinder 109d for the left rear wheel 65d via the pressure-varying oil paths L12a and L12d, a reservoir 114 linked to the pressure reduction solenoid valves 113a and 113d via a pressure reduction oil path L13 and to the oil supply path L10 via an oil path L14, and a pump 115 having an inlet connected to the reservoir 114 via an oil path L15 and an outlet connected to the oil supply path L11 via an oil path L16 with a check valve 116. Similarly the second system 120 includes an MC cut solenoid valve 121 connected with the master cylinder 101 via an oil supply path L20, and holding solenoid valves 122b and 122c linked to the MC cut solenoid valve 121 via an oil supply path L21 and respectively connected with the wheel cylinder 109b for the left front wheel 65b and with the wheel cylinder 109c for the right rear wheel 65c via pressure-varying oil paths L22b and L22c. The second system 120 also includes pressure reduction solenoid valves 123b and 123c respectively connected with the wheel cylinder 109b for the left front wheel 65b and with the wheel cylinder 109c for the right rear wheel 65c via the pressure-varying oil paths L22b and L22c, a reservoir 124 linked to the pressure reduction solenoid valves 123b and 123c via a pressure reduction oil path L23 and to the oil supply path L20 via an oil path L24, and a pump 125 having an inlet connected to the reservoir 124 via an oil path L25 and an outlet connected to the oil supply path L21 via an oil path L26 with a check valve 126.
The MC cut solenoid valve 111, the holding solenoid valves 112a and 112d, the pressure reduction solenoid valves 113a and 113d, the reservoir 114, the pump 115, and the check valve 116 included in the first system 110 respectively correspond to and are identical with the MC cut solenoid valve 121, the holding solenoid valves 122b and 122c, the pressure reduction solenoid valves 123b and 123c, the reservoir 124, the pump 125, and the check valve 126 included in the second system 120. Each of the MC cut solenoid valves 111 and 121 is a linear solenoid valve that is full open in the power cut-off condition (off position) and has the opening adjustable by regulation of the electric current supplied to a solenoid. The MC cut solenoid valve 111 or 121 couples and decouples the master cylinder 101 with and from the wheel cylinders 109a and 109d or with and from the wheel cylinders 109b and 109c and adjusts the differential pressure between the inlet and the outlet of the pump 115 or 125. Each of the holding solenoid valves 112a, 112d, 122b, and 122c is a normally-open solenoid valve that is closed in the power supply condition (on position). Each of the holding solenoid valves 112a, 112d, 122b, and 122c has a check valve activated to return the flow of brake oil to the oil supply path L11 or L21 when the wheel cylinder pressure in the corresponding one of the wheel cylinders 109a through 109d is higher than the hydraulic pressure in the oil supply path L11 or L21 in the closed position of the holding solenoid valve 112a, 112d, 122b, or 122c under the power supply condition (on position). Each of the pressure reduction solenoid valves 113a, 113d, 123b, and 123c is a normally-closed solenoid valve that is opened in the power supply condition (on position). The pump 115 of the first system 110 and the pump 125 of the second system 120 are actuated by respective non-illustrated drive motors (for example, duty-controlled brushless DC motors). The pump 115 or 125 takes in and pressurizes the brake oil in the corresponding reservoir 114 or 124 and supplies the pressurized brake oil to the oil path L16 or L26.
The brake actuator 102 of the above construction has the operations described below. In the normal off position of all the MC cut solenoid valves 111 and 121, the holding solenoid valves 112a, 112d, 122b, and 122c, and the pressure reduction solenoid valves 113a, 113d, 123b, and 123c (in the state of
On the driver's depression of the brake pedal 85, the brake actuator 102 actuates the pumps 115 and 125 with reduction of the openings of the MC cut solenoid valves 111 and 121 to introduce the brake oil from the master cylinder 101 to the reservoirs 114 and 124. The brake oil introduced from the master cylinder 101 to the reservoirs 114 and 124 has the pressure increased by the pumps 115 and 125 and is fed to the wheel cylinders 109a through 109d via the oil paths L16 and L26, the holding solenoid valves 112a, 112d, 122b, and 122c, and the pressure-varying oil paths L12a, L12d, L22b, and L22c. Actuation of the pumps 115 and 125 simultaneously with the opening adjustment of the MC cut solenoid valves 111 and 121 attains the braking assist and gives the braking force as the sum of the master cylinder pressure Pmc and the pressure increase by the pumps 115 and 125. Even in the state of the driver's release of the brake pedal 85, actuation of the pumps 115 and 125 simultaneously with the opening adjustment of the MC cut solenoid valves 111 and 121 enables the brake oil introduced from the reservoir 106 of the master cylinder 101 to the reservoirs 114 and 124 of the brake actuator 102 to be pressurized by the pumps 115 and 125 and to be fed to the wheel cylinders 109a through 109d. The individual on-off control of the holding solenoid valves 112a, 112d, 122b, and 122c and the pressure reduction solenoid valves 113a, 113d, 123b, and 123c individually and freely regulates the pressure in each of the wheel cylinders 109a through 109d. The brake actuator 102 thus attains traction control (TRC) to prevent a skid of the hybrid vehicle 20 due to the wheelspin of any of the front wheels 65a and 65b and the rear wheels 65c and 65d in response to the driver's depression of the brake pedal 85. The brake actuator 102 also attains attitude stabilization control (VSC) to prevent a sideslip of any of the front wheels 65a and 65b and the rear wheels 65c and 65d, for example, during a turn of the hybrid vehicle 20.
The brake actuator 102 is driven and operated under control of a brake electronic control unit (hereafter referred to as ‘brake ECU’) 105. More specifically the brake ECU 105 controls the operations of the MC cut solenoid valves 111 and 121, the holding solenoid valves 112a, 112d, 122b, and 122c, the pressure reduction solenoid valves 113a, 113d, 123b, and 123c, and each motor for actuating the pumps 115 and 125. The brake ECU 105 inputs the master cylinder pressure Pmc generated by the master cylinder 101 and measured by a master cylinder pressure sensor 101a, a negative pressure Pn in the brake booster 103 produced by the engine 22 and measured by a pressure sensor 103a, a signal from a pedal force detection switch 86 attached to the brake pedal 85 and mainly used in the event of a failure of the brake actuator 102, wheel speeds from respective wheel speed sensors (not shown) placed on the front wheels 65a and 65b and the rear wheels 65c and 65d, and a steering angle from a steering angle sensor (not shown). The brake ECU 105 makes communication with the hybrid ECU 70, the motor ECU 53, and the battery ECU 58. The brake ECU 105 controls the operation of the brake actuator 102 according to the input data including the master cylinder pressure Pmc and the negative pressure Pn, the state of charge (SOC) of the high-voltage battery 55, a rotation speed Nm of the motor, and control signals from the hybrid ECU 70, so as to attain the braking assist, the ABS control, the TRC, and the VSC. The brake ECU 105 outputs the operating conditions of the brake actuator 102 to the hybrid ECU 70, the motor ECU 53, and the battery ECU 58 according to the requirements.
The hybrid ECU 70 is constructed as a microprocessor including a CPU 72, a ROM 74 that stores processing programs, a RAM 76 that temporarily stores data, input and output ports (not shown), and a communication port (not shown). The hybrid ECU 70 receives, via its input port, an ignition signal from an ignition switch 80, a gearshift position SP or a current setting position of a gearshift lever 81 from a gearshift position sensor 82, an accelerator opening Acc or the driver's depression amount of an accelerator pedal 83 from an accelerator pedal position sensor 84, a signal from the pedal force detection switch 86, and a vehicle speed V from a vehicle speed sensor 87. The hybrid ECU 70 generates diverse control signals in response to these input signals and transmits control signals and data to and from the engine ECU 24, the CVTECU 46, the motor ECU 53, the battery ECU 58, and the brake ECU 105 by communication. The hybrid ECU 70 outputs, via its output port, for example, driving signals to the starter motor 26 and the alternator 28 linked to the crankshaft 23 and control signals to the electric oil pump 60.
In response to the driver's operation of the accelerator pedal 83, the hybrid vehicle 20 of the embodiment may be driven with the output power of the engine 22 transmitted to the front wheels 65a and 65b, with the output power of the motor 50 transmitted to the rear wheels 65c and 65d, or with both the output power of the engine 22 and the output power of the motor 50 as the four-wheel drive. The hybrid vehicle 20 is driven by the four-wheel drive, for example, in the event of abrupt acceleration by the driver's heavy depression of the accelerator pedal 83 or in the event of a skid or slip of any of the front wheels 65a and 65b and the rear wheels 65c and 65d. When the driver releases the accelerator pedal 83 to give an accelerator off-based speed reduction requirement at the vehicle speed V of not lower than a predetermined level, the hybrid vehicle 20 of the embodiment sets both the brake B1 and the clutch Cl off to decouple the engine 22 from the CVT 40, stops the operation of the engine 22, and performs the regenerative control of the motor 50. The regenerative control of the motor 50 applies the braking force to the rear wheels 65c and 65d to decelerate the hybrid vehicle 20. The regenerative electric power generated by the motor 50 during deceleration may be used to charge the high-voltage battery 55. This arrangement desirably enhances the energy efficiency in the hybrid vehicle 20.
The following describes the operations in the hybrid vehicle 20 of the embodiment having the above configuration, especially a series of braking control in response to the driver's depression of the brake pedal 85. An abnormality detection routine for the brake actuator 102 executed in the hybrid vehicle 20 of the embodiment is described first with reference to the flowchart of
At the execution timing of this abnormality detection routine, a non-illustrated CPU of the brake ECU 105 sets a duty ratio command value dp1 for the motor of the pump 115 to a preset value dpref and a duty ratio command value dv1 for the solenoid of the MC cut solenoid valve 111 to a preset value dvref (step S300). The motor of the pump 115 and the solenoid of the MC cut solenoid valve 111 are driven temporarily with the respective duty ratio command values dp1 (=dpref) and dv1 (=dvref) for a predetermined time period (for example, 3 to 6 msec) and are stopped after elapse of the predetermined time period (step S310). When both the pump 115 and the MC cut solenoid valve 111 temporarily driven for the check are in the normal state, regardless of the driver's depression or release of the brake pedal 85, there is a temporary pressure difference (pulsation) between both sides of the MC cut solenoid valve 111, that is, between the oil supply path L10 and the oil supply path L11. This pressure difference immediately disappears within a very short time period. The master cylinder pressure Pmc is input from the master cylinder pressure sensor 101a for only a preset time period after completion of the temporary actuation and stop at step S310 and is stored in a specific memory area (step S320). A variation in pressure difference αPmc is calculated from the input master cylinder pressure Pmc (step S330).
The calculated pressure difference variation αPmc is compared with a preset reference value ΔPref (step S340). The reference value ΔPref is experimentally and analytically obtained and represents a variation of the pressure difference in the case of temporary actuation of the pump 115 and the MC cut solenoid valve 111 with the respective duty ratio command values dp1 (=dpref) and dv1 (=dvref), on condition that both the pump 115 and the MC cut solenoid valve 111 are normal. When the calculated pressure difference variation αPmc is not less than the preset reference value ΔPref (step S340: yes), both the pump 115 and the MC cut solenoid valve 111 are identified as normal. In this case, an abnormality detection flag Fab1 is set to 0 (step S350). The setting of the abnormality detection flag Fab1 to 0 shows that pressurization of the brake oil by the pump 115 is normally executable in the first system 110 of the brake actuator 102. When the calculated pressure difference variation αPmc is less than the preset reference value ΔPref (step S340: no), on the other hand, there is some abnormality in at least either of the opening adjustment function (differential pressure adjustment function) of the MC cut solenoid valve 111 and the pressurization function of the pump 115. In this case, the abnormality detection flag Fab1 is set to 1 (step S360). The setting of the abnormality detection flag Fab1 to 1 shows that pressurization of the brake oil by the pump 115 is not normally executable in the first system 110 of the brake actuator 102. The abnormality detection routine is similarly executed for the second system 120 using a master cylinder pressure Pmc measured by a master cylinder pressure sensor 101b. When both the pump 125 and the MC cut solenoid valve 121 are identified as normal, an abnormality detection flag Fab2 is set to 0. The setting of the abnormality detection flag Fab2 to 0 shows that pressurization of the brake oil by the pump 125 is normally executable in the second system 120 of the brake actuator 102. When there is any abnormality in at least either of the opening adjustment function of the MC cut solenoid valve 121 and the pressurization function of the pump 125, the abnormality detection flag Fab2 is set to 1. The setting of the abnormality detection flag Fab2 to 1 shows that pressurization of the brake oil by the pump 125 is not normally executable in the second system 120 of the brake actuator 102. In response detection of any abnormality in pressurization of the brake oil by the pump 115 in the first system 110 or by the pump 125 in the second system 120 according to this abnormality detection routine, an alarm lamp on an instrument panel (not shown) is lit on to inform the driver of the abnormality.
The braking control routine executed by the brake ECU 105 in the hybrid vehicle 20 of the embodiment is described below with reference to the flowchart of
After the data input at step S100, the CPU computes a pedal force Fpd applied by the driver's depression of the brake pedal 85 from the input master cylinder pressure Pmc and the input negative pressure Pn (step S110). The procedure of this embodiment prepares and stores in advance variations in pedal force Fpd against the master cylinder pressure Pmc and the negative pressure Pn as a pedal force setting map in a ROM (not shown) of the brake ECU 105 and reads the pedal force Fpd corresponding to the given master cylinder pressure Pmc and the given negative pressure Pn from the pedal force setting map.
The master cylinder pressure Pmc input at step S100 is multiplied by a constant Kspec to set a master cylinder pressure Pmc-based operational braking force BFmc (step S130). The constant Kspec is determined according to the braking specification including the outer diameter of the brake rotors, the diameter of the wheels, the sectional area of the wheel cylinders, and the friction coefficient of the brake pads. The CPU then determines whether the braking force demand BF* computed at step S120 is not greater than the operational braking force BFpmc set at step S130 (step S140). On condition that the braking force demand BF* is not greater than the operational braking force BFpmc, the braking force demand required by the driver can be satisfied by only the master cylinder pressure Pmc-based operational braking force BFpmc. When the braking force demand BF* is not greater than the operational braking force BFpmc (step S140: yes), the CPU sets 0 to a target regenerative braking force BFr*, which is to be produced by regeneration of the motor 50, and sends the setting of the target regenerative braking force BFr* to the motor ECU 53 (step S240). The CPU then exits from this braking control routine. In this state, the master cylinder pressure Pmc-based operational braking force BFpmc is directly transmitted to the front wheels 65a and 65b and to the rear wheels 65c and 65d. The MC cut solenoid valves 111 and 121 are set in the off position to be kept full open.
On condition that the braking force demand BF* is greater than the operational braking force BFpmc, on the other hand, the braking force demand required by the driver can not be satisfied by only the master cylinder pressure Pmc-based operational braking force BFpmc. When the braking force demand BF* is greater than the operational braking force BFpmc (step S140: no), the CPU sets the result of subtraction of the operational braking force BFpmc set at step S130 from the braking force demand BF* computed at step S120 to the target regenerative braking force BFr*, which is to be produced by regeneration of the motor 50, and sends the setting of the target regenerative braking force BFr* to the motor ECU 53 (step S150). The regenerative braking force producible by regeneration of the motor 50 varies according to the rotation speed Nm of the motor 50 (that is, the vehicle speed V) and the state of charge SOC of the high-voltage battery 55. The target regenerative braking force BFr* set and sent at step S150 is not always coverable by the output from the motor 50. Under some conditions, the output of the motor 50 may be less than the target regenerative braking force BFr* and fail to satisfy the braking force demand BF* required by the driver. After sending the setting of the target regenerative braking force BFr* at step S150, the CPU determines whether the result of subtraction of the braking force demand BF* computed at step S120 from the sum of the effective regenerative braking force BFr input at step S100 and the operational braking force BFpmc set at step S130 is not less than a predetermined threshold value a (step S160). The threshold value a is determined experimentally and analytically by taking into account a variation in regenerative braking force during the driver's braking operation and is, for example, a positive value approximate to 0. In the case of an affirmative answer at step S160, the motor 50 is capable of outputting the target regenerative braking force BFr*. Namely the braking force demand BF* is satisfied by the sum of the master cylinder pressure Pmc-based operational braking force BFpmc and the regenerative braking force produced by the motor 50. The CPU then exits from the braking control routine of
In the case of a negative answer at step S160, on the other hand, the regenerative braking force actually output from the motor 50 is less than the target regenerative braking force BFr*. The output of the motor 50 may thus fail to satisfy the braking force demand BF* required by the driver. When BFr+BFpmc-BF* is less than the predetermined threshold value a (step S160: no), the result of subtraction of the effective regenerative braking force BFr input at step S100 and the operational braking force BFpmc set at step S130 from the braking force demand BF* computed at step S120 is set to a pressure increase-based braking force BFpp, which is based on the pressure increase induced by pressurization of the brake oil by the pumps 115 and 125 (step S170). The pumps 115 and 125 are actuated and controlled to pressurize the brake oil fed from the master cylinder 101 and thereby compensate for a potential insufficiency of braking force. After setting the pressure increase-based braking force BFpp, the CPU determines whether the settings of the abnormality detection flags Fab1 and Fab2 input at step S100 are both equal to 1 (step S180). When both the abnormality detection flags Fab1 and Fab2 are not equal to 1 (step S180: no), the CPU identifies the settings of the abnormality detection flags Fab1 and Fab2 (step S190). When both the abnormality detection flags Fab1 and Fab2 for the first system 110 and the second system 120 are identified as 0 at step S190, the CPU sets the duty ratio command value dp1 of the motor for the pump 115 in the first system 110, the duty ratio command value dv1 for the MC cut solenoid valve 111 in the first system 110, the duty ratio command value dp2 of the motor for the pump 125 in the second system 120, and the duty ratio command value dv2 for the MC cut solenoid valve 121 in the second system 120, based on the pressure increase-based braking force BFpp set at step S170 (step S200). In this embodiment, variations in duty ratio command values dp1 and dp2 for the pumps 115 and 125 against the pressure increase-based braking force BFpp or the pressure increase by the pumps 115 and 125 are specified and stored in advance as a pump command value setting map (not shown) in the ROM of the brake ECU 105. Similarly variations in duty ratio command values dv1 and dv2 for the MC cut solenoid valves 111 and 121 against the pressure increase-based braking force BFpp or the pressure increase by the pumps 115 and 125 are specified and stored in advance as a valve command value setting map (not shown) in the ROM of the brake ECU 105. The first system 110 and the second system 120 are laid out in the cross arrangement in the brake actuator 102 of the embodiment. According to the concrete procedure of this embodiment, the duty ratio command values dp1 and dp2 for the pumps 115 and 125 and the duty ratio command values dv1 and dv2 for the MC cut solenoid valves 111 and 121 are read corresponding to half (½) the pressure increase-based braking force BFpp set at step S170 respectively from the pump command value setting map and from the valve command value setting map. Such setting of the duty ratio command values dp1, dp2, dv1, and dv2 aims to make the braking force based on the pressure increase by the pump 115 of the first system 110 substantially equal to the braking force based on the pressure increase by the pump 125 of the second system 120. After setting of these duty ratio command values dp1, dp2, dv1, and dv2, the operation of the motors for the pumps 115 and 125 and the operation of the solenoids of the MC cut solenoid valves 111 and 121 are controlled respectively with the duty ratio command values dp1 and dp2 and with the duty ratio command values dv1 and dv2 (step S210). The CPU then exits from the braking control routine of
When the abnormality detection flag Fab1 for the first system 110 is identified as 1 and the abnormality detection flag Fab2 for the second system 120 is identified as 0 at step S190, there is some abnormality in the pressurization process of the brake oil by the pump 115 in the first system 110. The pump 125 and the MC cut solenoid valve 121 have no abnormality in the second system 120. In this state, the pressure increase by pressurization of the brake oil by the pump 125 in the normal second system 120 is to be enhanced to compensate for the failed pressure increase, which is to be attained by pressurization of the brake oil by the pump 115 in the abnormal first system 110. In order to achieve this requirement, the CPU sets the duty ratio command value dp2 for the pump 125 and the duty ratio command value dv2 for the MC cut solenoid valve 121 in the normal second system 120 corresponding to the pressure increase-based braking force BFpp, while setting 0 to the duty ratio command value dp1 for the pump 115 and the duty ratio command value dv1 for the MC cut solenoid valve 111 in the abnormal first system 110 (step S220). According to the concrete procedure of the embodiment, the duty ratio command value dp2 for the pump 125 and the duty ratio command value dv2 for the MC cut solenoid valve 121 are read corresponding to the pressure increase-based braking force BFpp set at step S170 respectively from the pump command value setting map and from the valve command value setting map. After setting of these duty ratio command values dp1, dp2, dv1, and dv2, the operation of the motor for only the pump 125 and the operation of the solenoid of only the MC cut solenoid valve 121 in the second system 120 are controlled respectively with the duty ratio command value dp2 and with the duty ratio command value dv2 (step S210). The CPU then exits from the braking control routine of
When the abnormality detection flag Fab1 for the first system 110 is identified as 0 and the abnormality detection flag Fab2 for the second system 120 is identified as 1 at step S190, there is some abnormality in the pressurization process of the brake oil by the pump 125 in the second system 120. The pump 115 and the MC cut solenoid valve 111 have no abnormality in the first system 110. In this state, the pressure increase by pressurization of the brake oil by the pump 115 in the normal first system 110 is to be enhanced to compensate for the failed pressure increase, which is to be attained by pressurization of the brake oil by the pump 125 in the abnormal second system 120. In order to achieve this requirement, the CPU sets the duty ratio command value dp1 for the pump 115 and the duty ratio command value dv1 for the MC cut solenoid valve 111 in the normal first system 110 corresponding to the pressure increase-based braking force BFpp, while setting 0 to the duty ratio command value dp2 for the pump 125 and the duty ratio command value dv2 for the MC cut solenoid valve 121 in the abnormal second system 120 (step S230). According to the concrete procedure of the embodiment, the duty ratio command value dp1 for the pump 115 and the duty ratio command value dv1 for the MC cut solenoid valve 111 are read corresponding to the pressure increase-based braking force BFpp set at step S170 respectively from the pump command value setting map and from the valve command value setting map. After setting of these duty ratio command values dp1, dp2, dv1, and dv2, the operation of the motor for only the pump 115 and the operation of the solenoid of only the MC cut solenoid valve 111 in the first system 110 are controlled respectively with the duty ratio command value dp1 and with the duty ratio command value dv1 (step S210). The CPU then exits from the braking control routine of
When both the abnormality detection flags Fab1 and Fab2 are identified as 1 at step S180, there is some abnormality both in the pressurization process of the brake oil by the pump 115 in the first system 110 and in the pressurization process of the brake oil by the pump 125 in the second system 120. In this state, the CPU immediately exits from the braking control routine of
In the hybrid vehicle 20 of the embodiment described above, the braking force demand BF* required by the driver is satisfied by the sum of the operational braking force BFpmc based on the master cylinder pressure Pmc and the braking force BFpp based on the pressure increase by the pumps 115 and 125. When both the first system 110 and the second system 120 of the brake actuator 102 are normal and enable the required pressurization of the brake oil, the operation of the brake actuator 102 included in the HBS 100 is controlled to attain pressurization of the brake oil by the pumps 115 and 125 in the first and the second systems 110 and 120 and satisfy the braking force demand BF* required by the driver (steps S200 and S210). When there is some abnormality in either of the first system 110 and the second system 120, the operation of the brake actuator 102 included in the HBS 100 is controlled to enhance the pressure increase by the pump in the normal braking system (the first system 110 or the second system 120) to a certain extent for compensating for a pressure increase expected to be attained by the pump in the abnormal braking system (the second system 120 or the first system 110) (step S220 or S230 and step S210). Such operation control attains pressurization of the brake oil by the pump in the normal braking system, that is, either by the pump 115 in the normal first braking system or by the pump 125 in the normal second braking system, and satisfies the braking force demand BF* required by the driver. The braking force demand BF* required by the driver is expected to be satisfied by the sum of the operational braking force BFpmc based on the master cylinder pressure Pmc and the braking force BFpp based on the pressure increase by the pumps 115 and 125. Namely the braking force based on the pressure increase by the pumps 115 and 125 is utilized to compensate for an insufficiency of the sum of the operational braking force BFpmc based on the master cylinder pressure Pmc and the regenerative braking force of the motor 50. There may be, however, some abnormality either in the pressurization process of the brake oil by the pump 115 in the first system 110 or in pressurization process of the brake oil by the pump 125 in the second system 120. Even in the event of such abnormality, the braking control executed in the hybrid vehicle 20 of the embodiment ensures satisfaction of the braking force demand required by the driver. The braking control of the embodiment sets the duty ratio command values dp1 and dp2 for the pumps 115 and 125 and the duty ratio command values dv1 and dv2 for the MC cut solenoid valves 111 and 121, based on the pressure increase-based braking force BFpp set at step S170 and the abnormality detection flags Fab1 and Fab2 set in the abnormality detection routine of
The abnormality detection routine shown in the flowchart of
In the hybrid vehicle 20 of the embodiment, the power of the engine 22 is transmitted to the front wheels 65a and 65b via the output shaft 42 or the driveshaft. The power of the engine 22 may alternatively be transmitted to the rear wheels 65c and 65d via the rear axle 66. The power of the engine 22 may be connected to a generator, instead of transmission to the front wheels 65a and 65b or to the rear wheels 65c and 65d. In this modified structure, the motor 50 may be driven with electric power generated by the generator or with electric power generated by the generator and accumulated in a battery. Namely the technique of the invention is also applicable to series hybrid vehicles. In the hybrid vehicle 20 of the embodiment, the power of the motor 50 is transmitted to the rear wheels 65c and 65d via the rear axle 66. The power of the motor 50 may alternatively be transmitted to the front wheels 65a and 65b. The belt-driven CVT 40 may be replaced by a toroidal CVT or a step transmission.
The embodiment discussed above is to be considered in all aspects as illustrative and not restrictive. There may be many modifications, changes, and alterations without departing from the scope or spirit of the main characteristics of the present invention. The scope and spirit of the present invention are indicated by the appended claims, rather than by the foregoing description.
The technique of the invention is preferably applied to automobile industries and relevant industries.
The disclosure of Japanese Patent Application No. 2006-141619 filed May 22, 2006 including specification, drawings and claims is incorporated herein by reference in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-141619 | May 2006 | JP | national |
