Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
2001-12-31
2004-01-13
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S076000, C303S122050
Reexamination Certificate
active
06678593
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and a method for monitoring a pressure sensor, which is positioned in a braking system of a vehicle.
BACKGROUND INFORMATION
Conventional devices and method for monitoring a pressure sensor are available. For example, the following procedure for monitoring a pressure sensor is described in the article “FDR—Die Fahrdynamikregelung von Bosch” [ESP—electronic stability program of Bosch] published in the automotive engineering journal ATZ Automobiltechnische Zeitschrift, vol. 96, issue no. 11 (1994) pp. 674 through 689: In order to monitor a pressure sensor, in this case an admission pressure sensor, a so-called active pressure sensor test is carried out. In this active pressure sensor test, braking pressure is fed into the braking system, using a pump included in the braking system, preferably using a precharge pump. At the same time, it is checked whether the pressure sensor signal is acting plausibly.
This kind of monitoring has the disadvantage that an active pressure buildup is required to carry out the pressure sensor test, and this is realized with the aid of a precharge pump. As a result, this pressure sensor test cannot be used for braking systems which do not have a precharge pump at their disposal. This kind of pressure sensor test also has the disadvantage that, during malfunctioning of the precharge pump, monitoring the pressure sensor is no longer possible.
Consequently, an object of the present invention is to create a device and a method for monitoring a pressure sensor which, respectively, do not require an active pressure buildup. That is, monitoring a pressure sensor is to be realized, without the use of a precharge pump.
German Patent Application DE 197 55 112 A1 does not describe a method or monitoring device for carrying out a pressure sensor test. However, this application describes a method and a monitoring device for determining fading of the braking action of a motor vehicle brake. To do this, the longitudinal acceleration of the vehicle is measured. The measured longitudinal acceleration is related to an ascertained braking operation. From this is determined whether the measured vehicle longitudinal acceleration corresponds to the braking operation. To determine the braking operation, in particular the braking pressure in a brake fluid line or the excursion of the brake pedal are measured.
SUMMARY
According to an example embodiment of the present invention, a device for monitoring a pressure sensor positioned in a braking system of a vehicle includes means whereby a first vehicle movement variable is ascertained during a braking action, which characterizes a vehicle motion in the longitudinal direction. The device, according to the example embodiment further includes means with which a mass variable is ascertained that characterizes the mass of the vehicle. Advantageously, for monitoring the pressure sensor, the device according to the present invention includes means with which are ascertained whether the first vehicle motion variable lies within a value range for the first vehicle motion variable, whose limits are ascertained as a function of the mass variable.
Since the first vehicle motion variable is a function of the vehicle mass, this procedure ensures that, for monitoring the pressure sensor, the first vehicle motion variable is compared to a “matching” value range, that is, to a value range adapted to the mass of the vehicle.
Advantageously, the first vehicle motion variable is ascertained during a braking action performed by the driver. To do this, only such braking actions are registered in which a regulating device contained in the vehicle does not execute any interventions on the vehicle brakes independently of the driver. Advantageously, the mass variable is ascertained during at least one drive operation. To do this, only such drive operations are registered in which a regulating device contained in the vehicle does not execute any interventions on the propulsion independently of the driver. Because, as the braking actions and/or the drive operations, only those are registered, on which no driver-independent interventions in the vehicle brakes and/or the propulsion are being carried out, one makes sure that monitoring of the pressure sensor in so-called stable operating states of the vehicle is being carried out. Due to this procedure for monitoring the pressure sensor, no precharge pump is necessary, since, at least within the framework of this monitoring, no driver-independent braking actions are necessary or rather, are taken into account. Thus, the monitoring of the pressure sensor according to the example embodiment of the present invention can also be used for braking systems which have no precharge pump, but instead have a pneumatic booster. Additionally, the pressure sensor can also be monitored if a precharge pump malfunctions in a braking system equipped with a precharge pump.
Using the pressure sensor monitored by the device and the method according to the present invention, an admission pressure variable is ascertained which describes the admission pressure set by the driver. As part of the sensor system, the device according to the present invention may be further provided with means with which wheel speed variables are ascertained, which describe the wheel speeds of the individual wheels. Advantageously, the first vehicle motion variable is ascertained as a function of the admission pressure variable and the wheel speed variables.
Advantageously, in the device according to the present invention, means are provided with which a first vehicle deceleration variable is ascertained, at least as a function of the admission pressure variable. This represents the vehicle deceleration to be expected theoretically on account of the operation of the brake by the driver. Ascertainment of the first vehicle deceleration variable is advantageously made by using a mathematical model. As parameters, this contains nominal values, i.e., fixed, predefined variables for the braking torque translation, namely, the wheel radius as well as the vehicle mass. Advantageously, the first vehicle deceleration variable is ascertained in a small timing window. Thus, one may assume that interfering influences, such as wind forces, downgrade forces or driving resistance forces have no influence.
In the device according to the present invention, further means are advantageously provided with which a second vehicle deceleration variable is ascertained, as a function of the wheel speed variables of the rear wheels. This represents the vehicle deceleration which actually occurs during the braking action. In order that the second vehicle deceleration variable represents the actually occurring vehicle deceleration as accurately as possible, those wheel speed variables of the wheels are used for ascertaining it which are less subject to slipping during a braking action. During a braking action, these are the rear wheels.
For the purpose of ascertaining the first vehicle motion variable, the first and the second vehicle deceleration variable are brought in relation to each other. In this connection, use is made of the fact that, during partial braking, a correlation exists between the admission pressure, which enters into the first vehicle deceleration variable and the vehicle deceleration that occurs, which is represented by the second vehicle deceleration variable. In the case in point, for the ascertainment of the first vehicle motion variable for successive time steps, in each case a relationship is formed between the present first and second vehicle deceleration variable, respectively. The first vehicle motion variable is formed as the average of these relationships. Since there is a connection between the first vehicle motion variable and the sensitivity of the pressure sensor, this first vehicle motion variable can be used to monitor the pressure sensor, in particular, to monitor the sensitivity of the pressure sensor.
As described above, the mathematical model for ascertaining the firs
Gansler Mike
Kachel Gerhard
Landesfeind Klaus
Otterbein Stefan
Chin Gary
Kenyon & Kenyon
Robert & Bosch GmbH
LandOfFree
Device and method for monitoring a pressure sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device and method for monitoring a pressure sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device and method for monitoring a pressure sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3246839