Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-07-26
2002-02-12
Camby, Richard M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S070000, C702S175000
Reexamination Certificate
active
06347269
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle mass calculation apparatus for calculating a vehicle mass for use in, for example, determining shift timing in an automatic transmission.
2. Description of the Related Art
In recent years, attempts have been made to achieve more efficient, more response of automatic transmissions to better match the driver's feelings. Specifically, shift timing and gear are determined based on various factors including not only vehicle speed and weight on the accelerator pedal, but also vehicle mass and the gradient of the road on which the vehicle is travelling.
Automatic transmissions, before mainly found in private vehicles, are now also employed in commercial vehicles such as taxis and buses. For private vehicles, a vehicle mass generally does not vary significantly because a relatively small number of passengers is carried, and the need of considering a vehicle mass as a variable in transmission control is therefore not great. However, for commercial vehicles, vehicle mass may vary significantly depending on the number of passengers, and it is therefore preferable to treat vehicle mass as a variable, rather than as a fixed value, in transmission control. Recently, even passenger vehicles come to find the need for a vehicle mass to be handled as a variable along with the permeation of the type, such as mini-vans, which can accommodate a relatively large number of passengers. Also, more accurate transmission control is now desired in conventional four-door sedans.
As a vehicle mass measurement method, there is available a method in which suspension displacement is measured with a vehicle in a still state, and another method in which vehicle mass is calculated using a load weight sensor provided to a suspension. Both these methods, however, can only be applied when the vehicle is not moving.
As a method for calculating a vehicle mass while the vehicle is travelling, one known method is based on the relationship between acceleration and driving force. Specifically, while a specific amount of driving force is being generated, vehicle mass is determined to be large when the vehicle only accelerates slightly, and is determined to be small when a large acceleration is generated.
Japanese Patent Laid-open Publication No. Hei 6-147304 discloses a technology for calculating vehicle mass by using a neural network which receives time series signals indicative of vehicle acceleration, vehicle speed, and opening of a throttle valve with the accelerator pedal being depressed. Japanese Patent Laid-open Publication No. Hei 6-201523 discloses vehicle mass calculation which a vehicle acceleration, a vehicle speed, and a throttle position of a vehicle having a less varying throttle position and running on a road of a constant gradient, are detected, and the detected data in two cases of different throttle position are compared to each other. These methods enable detection of a vehicle mass of a running vehicle.
However, the method described in JP Laid-open Publication No. Hei 6-147304 does not take road gradient into consideration. In other words, the road must be level for achievement of accurate vehicle mass calculation. In the method described in JP Laid-open Publication No. Hei 6-201523, gradients in the two cases subjected to comparison must be equal to each other. That is, the methods described in the above mentioned publications have a problem that the road gradient must be known within a certain degree of accuracy in order to achieve accurate vehicle mass calculation.
SUMMARY OF THE INVENTION
The present invention aims to provide an apparatus capable of calculating a mass of a vehicle in motion without being affected by road gradient.
In order to solve the above described problems, according to the present invention, there is provided a vehicle mass calculation apparatus, comprising acceleration calculating device for calculating a longitudinal acceleration of a vehicle to obtain an acceleration signal; driving force calculating device for obtaining a driving force signal corresponding to a driving force of a power plant of the vehicle; first signal processing device for removing influence of resistance acting on the vehicle from the acceleration signal to obtain a processed acceleration signal, second signal processing device for removing influence of resistance acting on the vehicle from the driving force signal to obtain a processed driving force signal and vehicle mass calculating device for calculating a vehicle mass based on the processed acceleration signal and the processed driving force signal.
The relationship between a force acting on a vehicle and vehicle acceleration in the longitudinal direction of a vehicle can be expressed as
(force acting on vehicle)=(vehicle mass)×(vehicle acceleration).
When the force acting on the vehicle and the vehicle acceleration are both known, vehicle mass can be calculated. A force acting on a vehicle mainly comprises a driving force caused by a power plant of a vehicle and a resistance force acting on the vehicle. A resistance force includes friction resistance (such as rolling resistance), air resistance, and resistance due to road gradient. Gradient resistance may vary depending on road gradient, whereas friction and air resistance (hereinafter together referred to as running resistance) are determined at a substantially fixed value for each vehicle. That is, forces other than gradient resistance can be obtained in advance once conditions such as a running speed and the state of a power plant are known.
A power plant constitutes a motor and a transmission device, and the motor is generally an internal combustion engine. An power of an internal combustion engine can be obtained in advance so as to correspond to an engine speed and a throttle position. When the transmission device has a slip transmission element, e.g., a torque converter, torque transmission or characteristic of the slip transmission element must be taken into consideration in calculating a driving force of the power plant.
Meanwhile, gradient resistance, which is resistance due to the gradient of a road where a vehicle is running and not the characteristic of the vehicle itself, cannot be obtained in advance. When a vehicle is running on a road with a constant gradient (including a level road), gradient resistance is a constant, and contains only a DC component in time series. Therefore, removal of the DC component will resultantly provide an equation of motion free from the influence of gradient. Even with an inconstant gradient, an equation of motion free from the influence of gradient can be obtained through specification and removal of a frequency band of the gradient resistance, affected by a change of road gradient. Removal of that frequency band can result in additional removal of the influence of a variation of friction resistance (such as rolling resistance) and air resistance as the frequency of that variation is also low.
In consideration of this property, the first and second signal processing device are filters for removing a frequency band affected by the influence of gradient. Moreover, as the influence of constant gradient appears as a DC component and that of a varying gradient is of a low frequency component, as described above, the first and second signal processing device are preferably high-pass filters for removing a low frequency component. The high-pass filter can additionally remove vehicle friction resistance and air resistance.
According to another aspect of the present invention, there is provided a device for calculating a mass of a vehicle loaded with a power plant including a motor and a transmission device, comprising device for calculating a first physical variable relative to an acceleration calculated by the output rotational speed of the transmission device to obtain a first signal; device for calculating a second physical variable relative to an input torque of the transmission device to obtain a second signal; device for storing transmiss
Hayakawa Kisaburo
Osawa Masataka
Oshima Masuji
Yoshida Hiroyuki
Camby Richard M.
Kabushiki Kaisha Toyota Chuo Kenkyusho
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