DE4236328C1 - Acceleration and inclination sensor for vehicle automatic transmission - detects position and deformation of freely movable mercury drop within arcuate hollow space contg. contact electrodes - Google Patents

Abstract

The sensor has a housing (4) enclosing a hollow space (6) with sidewalls (8,10) extending at an angle to its centre, containing a Hg drop (14) which moves in dependence on the applied acceleration and the inclination of the sensor housing (4) and varies in shape dependent only on the acceleration. A detector (16,18) monitors both the position and shape of the Hg drop (14), to provide separate acceleration and inclination values. The detector (16,18) has a response range allowing detection of deformation of the Hg drop caused by accelerations above 1g. It acts as a threshold detector with a series of response thresholds dependent on the size of the drop deformation. USE - For preventing switching of vehicle automatic transmission or operating roll-bar in critical travel conditions.

Description

The invention relates to an acceleration and Nei tion sensor, in particular for an automatic motor vehicle Gear, according to the preamble of claim 1 or 2.

In the German patent specification 41 14 992 C1 there is a combination ned acceleration and inclination sensor of this type show critical driving conditions in motor vehicles ben who both the motor vehicle inclination and un thereof depending on the applied vertical acceleration in the O-g range monitors and a warning signal, for example to actuate an over roll bar, delivers when the vehicle is in the state of Weightlessness is approaching and therefore a decreased or even lacks grip. For this purpose, means electrically conductive contact pieces in addition to the position of the contact body made of mercury in the cavity also the gravity-dependent self-deformation of the mercury body groped to meet the approaching weightlessness the direction of the gravitational field from a lens to a spherical shape passes. However, this sensor is on a pure two-point scan with a single, constant Response value with a vertical acceleration of less than 1-g restricts and offers no possibility to differentiate whether a change of position of the mercury body on a geän the vehicle inclination and / or on the influence of an additional Lich to the force of gravity to this perpendicular Querbe acceleration is based. Especially with automatic motor vehicles Conveyor gearboxes must be used for driving stability reasons Gear shift in driving conditions in which the lateral acceleration depending on the vehicle or lane inclination outside permissible  Limits. What to avoid with Hil fe of the combination sensor described above is not possible.

The object of the invention is the acceleration and Nei training sensor of the type mentioned so that he while maintaining a simple design without limitation a constant response value close to the acceleration-free one State an exact, combined inclination and acceleration measurement enabled.

This object is achieved by the claim 1 or 2 marked sensor solved.

With the combination sensor according to the invention, on the one hand according to claim 1, the outer contour changes of the contact body differentiated according to their size taking into account the con tactile body position scanned in the cavity and thereby critical cal acceleration states, for which depending on the direction of the loading difference in acceleration with respect to the sensor housing limit values apply, recorded with high reliability, and on the other hand, the response range of the Sen Sors on changes in the outer contour of the contact body above the 1 g limit extended, so that driving conditions in which too in addition to the acceleration due to gravity, especially horizon tal acceleration forces come into effect, who is detected that can. Because of the structurally very simple and reliable The invention is particularly suitable for sensor construction for the application described above, in which a Gear shift of the motor vehicle transmission in certain Nei acceleration and acceleration conditions for safety reasons must stay.

A particularly simple construction of the detector arrangement voltage is achieved according to claim 3 in that this as Threshold detector with several, each with regard to the Size of the outer contour change of the contact body gradually different response thresholds is formed. Because in many applications that have a critical inclination and External contour change indicating acceleration state with  increasing deflection of the contact body from the center of the cavity changes, the detector arrangement has another structural Simplification according to claim 4 from the cavity center from both gradually increased towards the sides of the cavity ends speaking thresholds.

A particularly preferred embodiment of the invention exists according to claim 5 in that when using one of a Liquid body, in particular mercury existing con clock body and electrically conductive, arranged in the cavity Contact pieces as a detector arrangement, the contact pieces in un different distances to the cavity boundary surfaces are ordered, making a structurally extremely simple differentiated according to the size of the outer contour changes Contact body scanning is achieved.

Exists, as in the preferred application of a motor vehicle gearbox, a fixed relationship between the inclination of the Sensor housing and the critical overall acceleration, so will the corresponding logical link according to another be particularly preferred aspect of the invention in the sensor itself integrated and thus the construction - but above all the Re effort - significantly reduced. Accordingly, the Detector arrangement according to claim 6 as on both sides of the hollow center of the room in an increasingly small space towards the ends of the cavities Ren height above the cavity boundary surface con Cycle comb designed to bridge any two Contact pieces provides a warning signal, which indicates that the total acceleration acting for the respective deflection kung of the contact body from the center of the cavity applicable, kriti has reached the limit value, whereupon a switchover of the Ge drive is prevented.

The invention will now be described with reference to that shown in the figures Exemplary embodiments explained in more detail. It show in strong matised representation:  

FIG. 1 is an acceleration and tilt sensor in the section in the untilted state and two driving states corresponding thereto (Fig. 1A and B.) of the associated motor vehicle;

. Fig. 2 is a corresponding view of Figure 1 of the sensor, however in the inclined state, and two driving states corresponding thereto (Fig. 2A and B) of the associated motor vehicle; and

Fig. 3 is a partial sectional view of the sensor housing to show the cross-sectional contour of the cavity with a modified detector arrangement.

The inclination and acceleration sensor 2 be in the figures consists of a two-part sensor housing 4 , z. B. made of glass, in which there is a cavity 6 curved upwards on both sides of the axis of symmetry S, which has a trough-shaped cross section ( FIG. 3) with boundary surfaces 8 , 10 inclined to the axis of symmetry S. The sensor 2 is mounted in the associated motor vehicle 12 such that the cavity 6 transversely to the longitudinal direction of the vehicle and the symme triaxis S is vertically aligned with the vehicle 12 not inclined.

As the sensor element of sensor 2 includes a inserted in the cavity 6 closed contact body 14 in the form of a mercury drop which is shown in FIG. 1 at tilt and horizontal acceleration-free motor vehicle 12 in 1-g-state (Fig. 1A) in the cavity center will be and takes on a somewhat flattened shape compared to the spherical shape. In this state, switching of the motor vehicle gearbox is permitted. If the motor vehicle 12 , on the other hand, traverses a curve on ho rontal roadway, then in addition to the earth acceleration g a transverse acceleration b comes into effect ( FIG. 1B), and the mercury drop 14 is corresponding to the direction of the resulting total acceleration vector a from the cavity center into the curve-shaped cavity branch deflected and flattened further, since the total acceleration a is greater than the acceleration due to gravity g. When a predetermined Querbe acceleration limit on the horizontal roadway, switching of the motor vehicle transmission must be prevented. The outer contour of the mercury drop 14 and its position in the cavity 6 in this driving state of the motor vehicle 12 are shown in Fig. 1 in dashed lines Li.

Fig. 2 shows the motor vehicle 12 on an inclined road, once in a standing position or when driving straight ahead under the effect of gravity ( Fig. 2a) and once when driving through a curve under the effect of a total acceleration vector a resulting from the additional lateral acceleration b FIG. 2B). Since in both cases the total acceleration, g or a, the amount and the direction according to the same as in FIG. 1, the respectively assigned, shown in solid or dashed lines deformation state of the contact body 14 is the size and direction after the same as acc. Fig. 1A and 1B, respectively, and only the position of the contact body 14 in the cavity 6 has Gert respective tilted position of the sensor housing 4 verla accordance with the road inclination, whereby in the lateral acceleration condition of FIG. 2A, a switching of the motor vehicle transmission due to the inclined position of the motor vehicle 12 Forbidden, however, when driving through an excessive curve ( Fig. 2B) is permitted because of the centrifugal acceleration b acting in addition to the gravitational acceleration g. If the transverse acceleration b increases further compared to the state shown in FIG. 2B, the mercury drop 14 migrates from the position shown in dashed lines in FIG. 2 with a continuously larger change in the outer contour in the direction of the cavity end on the right in the sense of FIG. 2, until the centrifugal acceleration b exceeds a limit value permissible for this inclination and the motor vehicle transmission must be locked again against a switching operation. The star ke inherent deformation of the contact body 14 and deflection from the center of the cavity is indicated in Fig. 2 in dash-dotted lines.

Another admissibility limit for the gearshift operation is sufficient if the vehicle 12 approaches the state of weightlessness and has reduced or even no ground contact. This state is also indicated by the contact body 14 in that it loses the flattened shape shown in FIGS. 1 and 2 regardless of its position in the cavity 6 and assumes a more spherical shape, as shown in Fig. 3 from the continuous outline of the contact body 14 can be seen.

With the sensor 2 described, switching-critical driving states can thus be detected very simply in such a way that a switching operation is always prevented when the outer contour change of the contact body 14 in relation to the spherical shape, a minimum value predetermined by the position of the contact body relative to the center of the cavity falls below, which is the smallest at the center of the cavity and on both sides of the axis of symmetry S in the direction of the cavity ends is increasingly larger. The necessary scanning of the contact body 14 is carried out by a detector arrangement 16 in the form of a contact comb, which consists of a plurality of closely adjacent contact pieces 18 in the longitudinal direction of the cavity. Whose height above the bottom surface 10 of the cavity 6 is accordingly the logical link between the switching release permitting minimum deformation and the position of the contact body 14 in the cavity 6 progressively reduced from the cavity center towards the cavity ends. The contact pieces 18 are each individually electrically connected to an evaluation circuit 20 which generates a warning signal W preventing the switching operation when two arbitrary adjacent contact pieces of the contact comb 16 are bridged by the contact body 14 . Accordingly, in the state of the contact body 14 shown in dashed lines in FIG. 1 and in the contact body states shown in solid and dash-dotted lines in FIG. 2, a warning signal W is generated by the evaluation circuit 20 , while in the driving states of FIGS. 1A and 2B the switching process is released. To avoid electrolysis, the contact is queried using an alternating voltage.

In applications where the critical self-deformation limit of the contact body 14 is not linked to the position of the contact body 14 in the cavity 6 according to a predetermined function, a modified detector arrangement 16 is provided according to FIG. 3. This consists of several. In the cavity longitudinal direction parallel to each other contact combs 16.1 to 16.8 , the contact pieces 18 each because in a different from contact comb to contact comb height above the lower vertex of the boundary surface 10 are arranged such that in any position of the contact body 14, the number of these bridged contact pieces 18 becomes smaller, the greater the deviation of the contact body 14 from the spherical shape. By querying all of the individual contacts 18 with the aid of the evaluation circuit 20 , it is therefore possible, in addition to the position of the contact body 14, to also detect the associated change in shape depending on their size and thereby the effective acceleration forces both with respect to the amount and with respect to the direction differentiated with respect to the axis of symmetry S.

Claims (6)

1. Acceleration and inclination sensor, in particular for an auto matic motor vehicle transmission, with a cavity formed in the sensor housing with limiting surfaces inclined toward the center of the cavity, at least one contact body arranged in a variable position according to the inclination of the sensor housing and the direction of the acting Ge overall acceleration, the one independently of the inclination of the sensor housing, the outer contour changes automatically depending on the acceleration, and with a detector arrangement that responds to an outer contour change and the position of the contact body in the cavity, characterized in that the detector arrangement ( 16 ) adjusts the outer contour changes of the contact body ( 14 ) depending on size has different responses. 2. Acceleration and inclination sensor, according to claim 1, in particular an automatic motor vehicle transmission, with a cavity formed in the sensor housing with ge inclined to the cavity center boundary surfaces, at least one in the cavity accordingly the inclination of the sensor housing and the direction of the total acceleration acting positionally arranged contact body, one independently of the inclination of the sensor housing has an outer contour that changes automatically as a function of acceleration, and with a detector arrangement that responds to a change in the outer contour and the position of the contact body in the cavity, characterized in that the response range of the detector arrangement ( 16 ) comprises outer contours of the contact body ( 14 ) that lie above the simple gravitational acceleration (1 g). 3. Acceleration and inclination sensor according to claim 1 or 2, characterized in that the detector arrangement ( 16 ) is designed as a threshold detector with several, each with respect to the size of the outer contour change of the contact body ( 14 ) gradually different response threshold values. 4. Acceleration and inclination sensor according to claim 3, characterized in that the response threshold values of the detector arrangement ( 16 ) from the cavity center on both sides in the direction of the cavity ends are gradually increased. 5. Acceleration and inclination sensor according to claim 3 or 4, in which the contact body consists of an electrically conductive liquid body, in particular mercury, and the detector arrangement consists of electrically conductive contact elements arranged in the cavity, characterized in that the contact pieces ( 18 ) are arranged at different distances from the cavity boundary surfaces ( 8 , 10 ). 6. Acceleration and inclination sensor according to one of claims 3 to 5, characterized in that the detector arrangement ( 16 ) from at least one, on both sides of the cavity center in an increasingly ge to the cavity ends lesser height above the cavity boundary surface ( 10 ) duri fenden contact comb ( 16.1 to 16.8 ).