Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2001-07-24
2002-10-01
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S022000, C701S051000, C180S065100, C180S065230, C180S065310
Reexamination Certificate
active
06459980
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a vehicle that may be braked with a motor as well as with a mechanical brake utilizing a frictional force, and also to a method of controlling such a vehicle. More specifically the present invention pertains to a vehicle that is braked with a motor to attain an arbitrarily adjustable speed reduction rate, as well as to a controlling method to actualize such braking.
BACKGROUND ART
A hybrid vehicle with both an engine and a motor as the power source has been proposed as one form of vehicles. For example, a hybrid vehicle disclosed in JAPANESE PATENT LAID-OPEN GAZETTE No. 9-37407 additionally has a motor placed in series between an engine and a transmission in a power system of an ordinary vehicle where an output shaft of the engine is connected with a drive shaft via the transmission. This arrangement enables the hybrid vehicle to be driven by means of both the engine and the motor as the power source. The engine generally has poor fuel consumption at a time of starting the vehicle. In order to avoid the driving of poor fuel consumption, the hybrid vehicle makes a start by utilizing the power of the motor. After the speed of the vehicle reaches a predetermined level, the hybrid vehicle starts its engine and is subsequently driven by utilizing the power of the engine. The hybrid vehicle accordingly improves the fuel consumption at the time of starting. The hybrid vehicle causes the motor to regenerate the rotations of the drive shaft as electric power, which is used for braking (hereinafter such braking is referred to as the regenerative braking). The hybrid vehicle carries out the regenerative braking and thereby enables the kinetic energy to be used without significant wastes. These characteristics desirably improve the fuel consumption of the hybrid vehicle.
There are two different types of braking in the vehicle. One braking process presses a brake pad against the drive shaft in response to actuation of a brake pedal, so as to apply a frictional force to the axle (hereinafter referred to as the wheel braking). The other braking process causes the power source to apply a load to the drive shaft, like engine brake (hereinafter referred to as the power source braking). The hybrid vehicle utilizes, as the power source braking, engine brake based on a pumping loss of the engine and regenerative braking due to a regenerative load of the motor. The power source braking does not require the driver to change the foot position from the accelerator pedal to the brake pedal for the purpose of braking. In order to enhance the effectiveness of the power source braking, it is desirable to arbitrarily set a speed reduction rate required by the driver.
The engine brake results in a substantially fixed speed reduction rate according to the engine speed, unless the open and close timings of an intake valve and an exhaust valve are changed. In order to attain a desired speed reduction rate by engine brake, the driver is required to operate a gearshift level to vary the gear ratio of the transmission and thereby change the ratio of the torque of the power source to the torque output to the drive shaft. The advantage of the regenerative braking of the motor is, on the other hand, relatively easy control of the regenerative load, which leads to relatively easy control of the speed reduction rate.
In the conventional hybrid vehicles, however, a diversity of problems as discussed below arise in the braking process utilizing the motor.
The first problem is that there has been no discussion on the possible range of the speed reduction rate set by the driver. Namely no discussion has been held on the desirable range of the speed reduction rate, in order to attain the stable driving of the hybrid vehicle.
The second problem is that the speed reduction rate can be set only in a variable range of the regenerative load of the motor. In some cases, the hybrid vehicle can not sufficiently attain the speed reduction rate required by the driver. The insufficient speed reduction rate occurs especially in the course of high-speed driving of the vehicle.
The third problem is that the driving state allowing the regenerative braking with the motor is relatively limited. For example, when the accumulator is in a state close to the full charge level, no further charging is allowed for the regenerative braking.
In such circumstances, the advantages of the power source braking, for example, actuation of braking without any change the foot position, are not fully utilized.
Utilizing the wheel braking to compensate for the insufficiency of the speed reduction rate damages the advantage of the power source braking that does not require any change of the foot position. The wheel braking causes the kinetic energy of the vehicle to be consumed in the form of thermal energy and accordingly damages the advantage of the hybrid vehicle that is the effective use of energy.
In the prior art hybrid vehicle, a large speed reduction rate may be attained by operating the gearshift lever to change the gear ratio of the transmission. In this case, however, the speed reduction rate drastically varies with the operation of the gearshift lever, which results in a poor ride..
The fourth problem is that there has been no discussion on the manipulation mechanism that allows the user to set the speed reduction rate. For the effective actuation of the regenerative braking, it is desirable that the user can arbitrarily and readily set the speed reduction rate. The desired speed reduction rate frequently varies according to the driving state of the vehicle, so that the easy change of the settings is demanded. It is, on the other hand, demanded to prevent an unintentional variation in speed reduction rate. No manipulation mechanisms for allowing the user to set the speed reduction rate have practically been proposed by considering such conditions.
The fifth problem is that there has been no discussion on the desired settings of the speed reduction rate at the respective gear ratios in response to the operation of the gearshift lever to change the gear ratio and the specification of the speed reduction rate. In order to fully utilize the advantage of the power source braking that does not require any change of the foot position from the accelerator pedal to the brake pedal and enhance the operatability of the hybrid vehicle, it is required to attain the speed reduction rate that well follows the driver's feeling. There has been no discussion from these viewpoints how the setting of the speed reduction rate should vary against the changing gear ratio, for example, in response to the specification of the speed reduction rate by the driver. In the prior art hybrid vehicles, there is still a requirement for the further improvement in effectiveness of the power source braking.
The sixth problem is that the energy recovery rate is lowered when the driver operates the gearshift lever to changeover the working range of the gear ratio. In the hybrid vehicle with a transmission, the driver operates the gearshift lever with a view to gaining a greater speed reduction rate and ensuring quick acceleration after the braking control. The driver may select a specific gearshift position where the positions of the change-speed gear having the greater gear ratios are available. In other words, the driver may select the gearshift position that prohibits the use of the positions of the change-speed gear having the smaller gear ratios.
In the prior art hybrid vehicle, the quantity of regeneration by the motor is reduced in such cases. This leads to the insufficient regeneration of the kinetic energy of the vehicle in the form of electric power.
In order to enhance the energy recovery rate of the vehicle, the braking control may be carried out at another specific gearshift position where the positions of the change-speed gear having the smaller gear ratios are available. This leads to a lesser ratio of the speed reduction rate applied to the axle to the braking torque of the power source. Due to this lesser ratio, th
Amano Masaya
Nakamura Seiji
Tabata Atsushi
Taga Yutaka
Cuchlinski Jr. William A.
Marc-Coleman Marthe Y.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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