Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
1999-12-10
2001-02-20
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
Reexamination Certificate
active
06190283
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to improvements in a driving force control system for a vehicle provided with a combination of an internal combustion engine and a motor-generator, and more particularly to the driving force control system for the vehicle provided with the engine and a transmission including two motor-generators.
A hybrid vehicle provided with the combination of an engine and a motor-generator has been hitherto known as disclosed in a paper No. 9832288 in a collection of previously printed papers for a science lecture of Society of Automotive Engineers of Japan. The vehicle is arranged to run under drive of at least one of the engine and the motor generator in order to reduce noxious exhaust emission. More specifically, a continuously variable transmission is incorporated with the engine and the motor-generator, so that power outputs of the motor-generator and the engine are controlled in accordance with vehicle operating conditions and a state of a battery.
Additionally, Japanese Patent Provisional Publication No. 62-110536 discloses a vehicle driving control system in which an engine and a continuously variable transmission are combined thereby to control a driving force in such a manner as to generate a target engine torque in accordance with a driver's requirement even during a transition time of speed-changing without using a torque sensor.
SUMMARY OF THE INVENTION
Drawbacks have been encountered in the above conventional techniques, as discussed below. That is, in the former conventional technique disclosed in the paper No. 9832288, when a target engine torque and a target input shaft rotational speed of the continuously variable transmission are set, a control accomplishes a so-called one input and two output manner in which the target engine torque and the target input shaft rotational speed are calculated in accordance with a target output shaft power output determined depending on the vehicle engine operating conditions. This minimizes freedom in setting of the target engine torque and the target input shaft rotational speed. For example, even under different engine operating conditions, the target engine torque and the target input shaft rotational speed always take respectively the same values if the determined target output shaft power output is the same. Consequently, a feeling of physical disorder will be provided to a driver particularly during engine acceleration in which variation in the target input shaft rotational speed or the engine speed is low relative to variation in the vehicle speed.
Additionally, in the former conventional technique in which the continuously variable transmission including planet gears is incorporated with the motor-generator, it is necessary to accomplish an electrical control for the motor-generator and the like and a mechanical control for the transmission. This requires two kinds of control systems thereby complicating the arrangement of a control system while increasing production cost of the vehicle.
In the latter conventional technique disclosed in Japanese Patent Provisional Publication No. 62-110536, a control system is configured such that the target input shaft rotational speed is determined in accordance with a target driving torque and a vehicle speed, in which a target power output is not calculated though an engine speed can be set in accordance with the vehicle speed. Accordingly, for example, it cannot correct the loss of a motor-generator nor realize power generation in accordance with the charged state of the battery. This makes it impossible to incorporate the motor-generator with the control system.
It is an object of the present invention to provide an improved driving force control system for a vehicle, which can effectively overcome drawbacks encountered in conventional similar driving force control systems.
Another object of the present invention is to provide an improved driving force control system for a vehicle equipped with a combination of an engine and a motor-generator, which makes it possible to change an engine speed in accordance with a vehicle speed, thereby precisely carrying out a speed-changing control for the vehicle.
A further object of the present invention is to provide an improved driving force control system for an automotive vehicle equipped with a combination of an engine and a continuously variable transmission including two motor-generators, which makes it possible to change an engine speed in accordance with a vehicle speed, thereby precisely carrying out a speed-changing control for the vehicle.
A first aspect of the present invention resides in a driving force control system for a vehicle, comprising a transmission including a first motor-generator connected to an engine, and a second motor-generator connected to driven wheels and driven by electric power generated by the first motor-generator. A first rotational speed sensor is provided for detecting a rotational speed of the first motor-generator. A second rotational speed sensor is provided for detecting a rotational speed of the second motor-generator. A control unit is provided programmed to control the rotational speed of the first motor-generator in accordance with the rotational speed of the second motor-generator. Additionally, the control unit is programmed to control a ratio between a first driving frequency for the first motor-generator and a second driving frequency for the second motor-generator so as to control the rotational speeds of the first and second motor-generators.
A second aspect of the present invention resides in a driving force control system for a vehicle, comprising a transmission including a first motor-generator connected to an engine, and a second motor-generator connected to driven wheels. Additionally, a control unit is provided programmed to carry out (a) calculating a first target driving torque in accordance with at least one of an operating condition of the vehicle and a driver's operation for the vehicle, (b) calculating a target power output in accordance with the first target driving torque and a value representative of a vehicle speed, (c) correcting the target power output in accordance with an operating condition of the transmission, (d) setting a second target driving torque upon calculating the second target driving torque in accordance with the corrected target power output and the value representative of the vehicle speed, (e) setting a target input shaft rotational speed of the transmission upon calculating the target input shaft rotational speed in accordance with the second target driving torque and the value representative of the vehicle speed, (f) setting a target engine torque upon calculating the target engine torque in accordance with a speed-changing ratio set for the transmission and the second target driving torque, the target engine torque, and (g) controlling the first motor-generator in accordance with the target input shaft rotational speed, and (h) controlling the second motor-generator in accordance with the first target driving torque.
A third aspect of the present invention resides in a method of controlling driving force for a vehicle provided with a transmission including a first motor-generator connected to an engine, and a second motor-generator connected to driven wheels and driven by electric power generated by the first motor-generator, a first rotational speed sensor for detecting a rotational speed of the first motor-generator, and a second rotational speed sensor for detecting a rotational speed of the second motor-generator. The driving force controlling method comprises (a) controlling the rotational speed of the first motor-generator in accordance with the rotational speed of the second motor-generator; and (b) controlling a ratio between a first driving frequency for the first motor-generator and a second driving frequency for the second motor-generator so as to control the rotational speeds of the first and second motor-generators.
A fourth aspect of the present invention resides in a method of controlling
Foley & Lardner
Nissan Motor Co,. Ltd.
Wright Dirk
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