Measuring and testing – Speed – velocity – or acceleration – Recording or registering interrelated factors
Patent
1993-06-30
1995-07-25
Raevis, Robert
Measuring and testing
Speed, velocity, or acceleration
Recording or registering interrelated factors
G01F 1500
Patent
active
054351847
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for determining running variables in a motor vehicle, comprising at least two acceleration sensors to determine the longitudinal and transverse acceleration of the motor vehicle and an evaluation circuit with a resettable time measuring unit which determines acceleration values from the sensor signals over a given period of time.
A device of the above-mentioned type is disclosed, for example, in DE-A-39 20 091. Like many other devices of this type, the device described there serves for triggering safety functions in the motor vehicle with the occurrence of certain acceleration values or a certain combination of acceleration values. Such safety functions are, for example, the lighting up of a warning lamp, the positioning of a roll bar, the activation of a belt tightener and/or of an air bag, etc. The common feature of all these devices is that they are, as a rule, integrated in the vehicle.
It is the object of the invention to provide a simple and economical device of the type stated at the outset which is vehicle-independent and can also be retrofitted to any vehicle and which nevertheless operates independently of actuation by the driver.
In order to achieve this object, the device stated at the outset comprises, according to the invention, a signal divider connected to the signal output of each acceleration sensor to divide the particular sensor signal into a low-frequency signal component (LF component) characterizing the vehicle acceleration and a high-frequency signal component (HF component), an adder connected to the LF output of the signal dividers for the vectorial addition of the LF components corresponding to the longitudinal acceleration components and to the transverse acceleration components, a storage unit connected to the adder and the time measuring unit to store the calculated acceleration values over the measured time and a control unit connected to the HF outputs of the signal dividers to control the time measuring unit.
The HF component of the sensor signals detects vibrations of the motor vehicle and sound waves, such as engine noises and/or roll noises. It is therefore possible to control the device according to the invention as a function of the operating state of the vehicle, i.e. for example to switch on the time measuring unit when the engine is switched on, without the device consequently having to be coupled to the ignition lock. It is this feature in particular which makes the device vehicle-independent and permits problem-free subsequent installation and removal of the device.
The storage of the acceleration values over time permits an analysis of the driver's behavior. From the stored values, it is possible to determine whether the driver has accelerated or braked particularly strongly over the measurement period, whether he has taken curves at very high speed, etc. These values can be compared with an average diagram in order to be able to evaluate the driver's behavior.
If only acceleration values above a certain level are to be measured, it is expedient if a component threshold circuit is arranged between the LF output of the particular acceleration sensor and the adder, said circuit passing on to the adder only an LF component which exceeds the threshold value specified for the particular acceleration component.
In order as far as possible to prevent the time measuring unit being switched on, and hence the device started up, by vibrations or noises not emanating from the vehicle, the control unit can comprise a main switch controlling the time measuring unit and a second threshold circuit which is connected to the HF outputs of the signal dividers and switches on the main switch when the HF component of at least one of the two acceleration signals exceeds the specified threshold value. Even greater security against extraneous influences is achieved if the second threshold circuit is down-circuit of a first time unit which switches off the main switch when the HF component of both acceleration signals remains below the threshold value of
REFERENCES:
patent: 3713343 (1973-01-01), Segerdahl et al.
patent: 4101869 (1978-07-01), Henderson
patent: 4114450 (1978-09-01), Shulman et al.
patent: 4460902 (1984-07-01), Beckman
Junker Thomas
Pineroli Bruno
Vonwyl Edouard
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