Measuring and testing – Test stand – For engine
Reexamination Certificate
1997-08-07
2001-04-24
Dombroske, George (Department: 2855)
Measuring and testing
Test stand
For engine
C701S110000
Reexamination Certificate
active
06220085
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention broadly relates to a vehicle-velocity calculating apparatus. More particularly, the invention relates to a vehicle-velocity calculating apparatus, for example, for obtaining velocity information required for performing positional calculation in a vehicle navigation system.
2. Description of the Related Art
In a conventional navigation system, the following type of vehicle-velocity calculating apparatus is available: an apparatus which uses a signal output from a vehicle-loaded velocity sensor so as to obtain velocity information required for performing positional calculation.
Another type of vehicle-velocity calculating apparatus is available in a known navigation system. An apparatus is provided with an acceleration sensor for detecting the acceleration of a vehicle traveling in a forward direction. The apparatus then integrates an output signal of the acceleration sensor with respect to time, thereby calculating the vehicle velocity.
However, signals cannot be readily extracted from the vehicle-loaded velocity sensor to the exterior, which inconveniently requires extra wiring work. Further, there is a difference in the method of outputting signals from the velocity sensor among the types of vehicles, and there may be some cases where signals cannot be extracted at all. Additionally, the following problem is encountered by a vehicle-velocity calculating apparatus which obtains the vehicle velocity by integrating a signal from the acceleration sensor with respect to time. If a vehicle travels downward, for example, on a slope, the integrated value representing the gravitational acceleration is disadvantageously output as the vehicle velocity.
SUMMARY OF THE INVENTION
Accordingly, it is a major object of the present invention to provide a vehicle-velocity calculating apparatus which is easily mounted on a vehicle, free from the influence of the gravitational acceleration.
In order to achieve the above object, according to one aspect of the present invention, there is provided a vehicle-velocity calculating apparatus comprising: a first means connectable to an output of a power line of a vehicle for obtaining a signal corresponding to a frequency or a period of a pulsating component generated in the vehicle's generator which appears at the output; and second means for obtaining a signal corresponding to an operating velocity of the vehicle in accordance with an output signal from the counter.
Preferably, the first means includes a counter and the second means includes a calculating circuit.
With this arrangement, in the above-described vehicle-velocity calculating apparatus, the counter measures the frequency or the period of a pulsating component contained in a power line, and outputs a signal representing the measured frequency or the period of the pulsating component. A pulsating component contained in the power line is generated in a generator (alternator). The frequency or the period of the pulsating component is proportional to the engine speed, and the engine speed is proportional to the vehicle running velocity. Namely, there is a proportional relationship between the vehicle running velocity and the frequency or the period of a pulsating component generated in a vehicle's generator. Based on this relationship, the calculation circuit calculates the vehicle operating velocity in accordance with an output signal from the counter.
Further, according to another aspect of the present invention, there is provided a vehicle-velocity calculating apparatus comprising: a counter connected to a vehicle power line via a noise filter, the counter being for obtaining a signal corresponding to a frequency or a period of a pulsating component generated in a vehicle's generator; a differentiating circuit for differentiating an output signal from the counter with respect to time; a calculating circuit for obtaining a signal corresponding to a provisionally determined acceleration in accordance with an output signal from the differentiating circuit; an acceleration sensor for obtaining a correction signal to correct the signal corresponding to the provisionally determined acceleration obtained by the calculating circuit; a correction circuit for correcting, based on the correction signal, the signal corresponding to the provisionally determined acceleration obtained by the calculating circuit; and an integrating circuit for integrating with respect to time the signal corresponding to the acceleration corrected by the correction circuit, thereby obtaining a signal corresponding to the operating velocity.
With this arrangement, in the above-described vehicle-velocity calculating apparatus, the counter determines the frequency or the period of a pulsating component contained in the power line, and outputs a signal indicating the determined frequency or the period. The output signal from the counter is differentiated with respect to time by the differentiating circuit. The differentiated signal output from the differentiating circuit is then input into the calculating circuit and is converted into a signal corresponding to a provisionally determined acceleration. The provisional acceleration signal may sometimes contain errors due to various circumstances, such as a change in the gear ratio caused by a shift change. In order to correct for the above errors, the acceleration sensor is provided to detect various circumstances, such as those where there occurs a sudden change in the acceleration caused by a shift change or a vehicle is moving backward. Based on a determination, the acceleration sensor outputs a correction signal for correcting the provisional acceleration signal. Based on this correction signal, the correction circuit corrects errors contained in the provisional acceleration signal and obtains a signal representing the correct acceleration. The correct acceleration signal is further integrated with respect to time by the integration circuit. As a consequence, a signal indicating the operating velocity can be obtained.
The vehicle-velocity calculating apparatus of the present invention is easy to mount on a vehicle without needing extra work because a cigarette lighter outlet or an audio power outlet which is provided in a vehicle may be used as a vehicle power line to connect the apparatus to the vehicle. Accordingly, the vehicle running velocity can be readily obtained by this apparatus. Moreover, the apparatus calculates the vehicle velocity through the use of a pulsating component contained in the power line, thus being free from an influence of the gravitational acceleration. Additionally, power supplied from the vehicle power line may be used as operating power, thereby enhancing the simplicity of the apparatus.
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Patent Abstracts of Japan, vol. 012, No. 231, Jun. 30, 1988 & JP 63 024166, Feb. 1, 1988.
Patent Abstracts of Japan, vol. 011, No. 278, Sep. 9, 1987 & JP 62-077803, Apr. 10, 1987.
Dombroske George
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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