DE102015003955A1 - Method for a vehicle chassis with air suspension system for adjusting a contact pressure, at least one vehicle wheel of a vehicle axle, on the roadway to be traveled - Google Patents

Abstract

The basic idea of the invention or the method according to the invention lies in the fact that the Bernoulli effect is specifically used to counteract lift at the rear of the vehicle by the vehicle acquiring predetermined / desired (better) air flow characteristics by varying the vehicle inclination, and thus the vehicle at the rear of the vehicle a higher contact force of the rear wheels relative to the road (adjustable) obtained.

Description

Field of the invention

The present invention relates to a method for a vehicle chassis with air spring system for adjusting a contact pressure, at least one vehicle wheel of a vehicle axle, on the roadway to be traveled.

Background of the invention

In the past, when motor vehicles were regarded as a mere means of transportation, in terms of comfort / comfortable travel the expectations of the buyers of a vehicle steadily increased.

An essential aspect, or contribution to this provides the vehicle chassis, by means of this z. B. unevenness in the roadway are balanced or damped.

In the vehicle middle class and in particular in the premium vehicles reinforced air spring systems are installed, since air spring systems over conventional damping systems steel springs have certain advantages.

In addition to the creation of a high comfort factor, the vehicle chassis with the damping system is also significantly responsible for the reliability (stability) of the motor vehicle significantly.

From the publication DE 10 2013 008 655 A1 a generic method for level control of an air suspension vehicle is known, which has a luftgefederte front axle and at least one air-sprung rear axle, and in which arranged between the chassis elements of the vehicle axles and the vehicle body air spring bellows for regulating a predetermined target level (xsoll) via switching valves designed as level control valves vented when falling below a lower tolerance limit (xT_u) of a tolerance band (.DELTA.xT) and vented when exceeding an upper tolerance limit (xT_o) of the tolerance band (.DELTA.xT), and at least one of the two tolerance limits (xT_u, xT_o) in the presence of a specific operating condition is changed suitably for at least one air spring bellows at least one vehicle axle or a vehicle side.

As from the Scriptures DE 10 2013 008 655 A1 further, this method is used to ultimately achieve a target level adjustment for all air springs.

As is known from general physics on the subject of fluid dynamics, a moving object at the rear end creates a buoyancy, wherein the buoyancy strongly depends on the shape of the object.

In aviation, this effect (so-called Bernoulli effect) is deliberately exploited in order to generate lift based on the shape of the wing. Due to the wing shaping, the air flows around the wing at the top faster than at the bottom, so that the higher speed leads to a low pressure above the wing, so that the wing is sucked upwards.

What is desired in aviation, however, is exactly the opposite in the field of motor vehicle technology, since with increasing speed in the rear region of the vehicle, a "negative pressure" is generated, which causes the vehicle to lose traction in the rear region reduce the contact pressure of the rear wheels on the road, so that ultimately suffers at higher vehicle speeds, the security severely.

In order to compensate for or counteract this effect, some rear spoilers are mounted on the vehicle (especially in racing), so that pressure is applied downward by means of the rear spoiler, and thus the contact force of the rear wheels relative to the road increases at higher vehicle speeds.

A disadvantage of the (usually sporty acting) rear spoilers is that they often do not fit the optical shape of the vehicle, especially if it is more noble vehicle series. In some vehicle series, the rear spoilers are therefore realized retractable or retractable.

From the publication DE 10 2013 008 655 A1 For this purpose, no further information is known, which discusses this in motor vehicle technology very undesirable effect (so-called Bernoulli effect) in more detail, and also does not disclose any suitable Abstellmaßnahme / countermeasure.

Presentation of the invention

It is an object of the present invention to increase road safety.

This object is achieved by a method according to claim 1, and a vehicle according to claim 10. Exemplary embodiments will become apparent from the dependent claims and the description below.

The basic idea of the invention or the method according to the invention lies in the fact that the Bernoulli effect is specifically used to counteract lift at the rear of the vehicle by the vehicle acquiring predetermined / desired (better) air flow characteristics by varying the vehicle inclination, and thus the vehicle at the rear of the vehicle a higher contact force of the rear wheels relative to the road (adjustable) obtained.

According to the invention, the method for a vehicle chassis with air spring system for adjusting a contact force, at least one vehicle wheel of a vehicle axle on the road to be traveled, executed / trained that in an air-suspension vehicle having an air-sprung front axle and an air-sprung rear axle, several between Chassis elements of the suspension axles and the vehicle body arranged air spring bellows to control their actual level can be vented to a predetermined target level via trained as switching valves level control valves and / or vented.

According to the invention, the aerodynamic laws which are dependent on the vehicle speed are used for this purpose in order to effect a change in a contact pressure force of at least one vehicle wheel of a vehicle axle on the roadway to be traveled.

In the method according to the invention, an increase in the contact forces of the vehicle wheels of the rear axle relative to the driving roadway is effected by (when driving) the vehicle body is raised in the region of the rear axle relative to the region of the front axle ( 2 ).

In the further alternative method according to the invention, an increase in the contact forces of the vehicle wheels of the rear axle relative to the driving roadway is effected by lowering the vehicle body in the region of the front axle relative to the region of the rear axle (while driving) ( 3 ).

In the method according to the invention, the raising and / or lowering of the vehicle body by ventilation (feel) and / or venting of the air spring bellows is effected on the corresponding vehicle axles.

In an advantageous embodiment, in the method according to the invention, at least in the region of the air-sprung rear axle, sensors for detecting measured variables are arranged whose signals or information are included and evaluated.

In an advantageous embodiment, in the method according to the invention by means of the sensors, the contact forces of the vehicle wheels of the rear axle are detected in a direct and / or indirect manner in relation to the roadway to be traveled.

In an advantageous embodiment, the sensors are designed as force sensors in the method according to the invention, so that the contact forces of the individual wheels relative to the roadway can be detected directly and a variation of the vehicle inclination angle (α) can be carried out if the measured variable (contact force) is too small. so that as a result, the contact pressure of the rear wheels relative to the road increases accordingly.

In an alternative advantageous embodiment, the sensors are designed as displacement sensors in the method according to the invention, so that the contact forces of the individual wheels relative to the road surface can be detected indirectly and a variation of the vehicle inclination angle (α) is made if the measured variable is too small (too large rebound) can be, so that as a result, the contact pressure of the rear wheels relative to the road increases accordingly.

In the method according to the invention, the aerodynamic laws are used in such a way that by means of ventilation and / or venting of one or more bellows, the vehicle speed-dependent buoyancy force due to the resulting air flow is changed such that the buoyancy force is reduced at the rear vehicle body region relative to the front vehicle body region, and thus the vehicle speed-dependent buoyancy force is counteracted in the rear area, which ultimately causes a higher contact pressure of the rear vehicle wheels opposite to the roadway.

In an advantageous embodiment, in the method according to the invention, the buoyancy force (p) at the rear vehicle area by means of the sensors ( 4.2 ), and depending on the vehicle inclination (α) by means of ventilation and / or ventilation of one or more air bellows ( 3.1 . 3.2 ) varies until a presettable desired contact pressure force on the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ). By this method, the weights of the payload in the trunk, the passengers in the rear of the vehicle, the tank filling can be taken into account, on the other hand, too large a contact force of the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ) should be avoided, since a too large contact pressure has a negative effect on the cW value and with a increased fuel consumption of the vehicle is associated / connected.

Furthermore, the invention comprises a vehicle, in particular designed as a motor vehicle, which is provided with a chassis with air spring system, which functionally has a method according to the method described above.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with those in the 1 to 5 illustrated embodiments. All described and / or illustrated features alone or in any combination form the subject matter of the present invention, also independent of their summary in the claims or their back references. It should also be noted that the invention is not limited to these embodiments. The same reference numerals designate the same or corresponding features. The features described in the examples can also be combined between the examples and be realized independently of the specific example.

In the specification, claims, abstract and accompanying drawings, the terms and associated reference numerals used in the list of reference numerals recited below are used.

The invention will now be described below with reference to several embodiments with the aid of 1 to 5 explained in more detail.

Brief description of the figures:

1 shows a representation of a vehicle with the essential components required for the inventive method.

2 shows a representation of a vehicle according to a first embodiment of the method according to the invention.

3 shows a representation of a vehicle according to a second embodiment of the method according to the invention.

4 shows a representation of the operation of the method according to the invention.

5 shows a representation of the operation of the method according to the invention with reference to a practical example.

Description of exemplary embodiments:

1 shows a representation of a vehicle with the essential components required for the inventive method, wherein the 1 shows how the individual components are used, as is known in the prior art.

The 1 shows the vehicle ( 1 ) with a front wheel ( 1.1 ) and a rear wheel ( 1.2 ), whereby the wheels ( 1.1 . 1.2 ) in the area of the vehicle axles ( 2.1 . 2.2 ) are located. The front wheel ( 1.1 ) is the front axle ( 2.1 ), which is designed as air-suspension front axle, and the rear wheel ( 1.2 ) is the rear axle ( 2.2 ) assigned, which is designed as air-suspension rear axle.

As the 1 shows, between the chassis elements of the chassis axles ( 2.1 . 2.2 ) and the vehicle body Luftfederbälge ( 3.1 . 3.2 ) arranged to control their actual level to a predetermined target level, which are vented and / or vented via not shown in detail as switching valves designed level control valves. Replacement (greatly simplified) is this a control unit ( 3.0 ), which is used for aerating and ventilating the bellows ( 3.1 . 3.2 ), technically with lines ( 3.3 ) with the bellows ( 3.1 . 3.2 ) connected is.

Like from the 1 can be further seen, is here assumed or shown with the dashed line that the vehicle ( 1 ) no inclination to the road ( 5 ) having. For this purpose, the dashed line is parallel (with the distance a) extending to the road to be traveled ( 5 ).

Like from the 1 can be seen further, arises at the rear / at the rear vehicle body of the vehicle ( 1 ) by physical laws as a result of the resulting air flow, a vehicle speed-dependent buoyancy force (p), which causes the contact forces of the rear wheels ( 1.2 ) opposite the carriageway ( 5 ) decrease correspondingly at higher vehicle speeds.

As a contact force / contact forces acting on the individual wheels, z. B. in a stationary vehicle to understand the forces resulting from the gross vehicle weight (gross: own vehicle weight including loading, occupants, tank filling, ...), divided on the individual wheels result.

2 shows a representation of a vehicle ( 1 ) according to a first embodiment of the method according to the invention. In addition to 1 show the 2 in the area of the air-sprung rear axle ( 2.2 ), a sensor ( 4.2 ) (or sensors 4.2 ) for the acquisition of measured variables, wherein the sensor ( 4.2 ) with a signal line ( 4.3 ) (or signal lines 4.3 ) with the control unit ( 3.0 ) connected is.

Deviating from the 1 , show the 2 in that the rear air bag ( 3.2 ) (the rear bellows 3.2 ) is more ventilated (filled) than the front air bag (is) 3.1 ) (the front air bellows 3.1 ). The stronger ventilation of the rear air bellows ( 3.2 ) relative to the front air bellows ( 3.1 ) causes like this from the 2 it can be seen that the vehicle ( 1 ) a forward inclination (α) to be driven to the road ( 5 ) having.

This forward inclination (α) opposite to the roadway ( 5 ) is shown with the dashed line, which in the rear of the vehicle to the road ( 5 ) has the distance (a + x) which is greater than the distance (a) at the front of the vehicle.

3 shows a representation of a vehicle according to a second embodiment of the method according to the invention. In addition to 1 show the 3 in the area of the air-sprung rear axle ( 2.2 ), a sensor ( 4.2 ) (or sensors 4.2 ) for the acquisition of measured variables, wherein the sensor ( 4.2 ) with a signal line ( 4.3 ) (or signal lines 4.3 ) with the control unit ( 3.0 ) connected is.

Deviating from the 1 , show the 3 in that the front air bag ( 3.1 ) (the front air bellows 3.1 ) is (are) vented more than the rear air bellows ( 3.2 ) (the rear bellows 3.2 ). The stronger ventilation of the front air bellows ( 3.1 ) relative to the rear air bellows ( 3.2 ) causes like this from the 3 it can be seen that the vehicle ( 1 ) a forward inclination (α) to be driven to the road ( 5 ) having.

This forward inclination (α) opposite to the roadway ( 5 ) is shown with the dashed line, which in the front vehicle area to the road ( 5 ) has the distance (a - x) which is smaller than the distance (a) at the rear of the vehicle.

The in the 2 and 3 shown inclination (α) causes the vehicle speed-dependent buoyancy force (p) is changed due to the resulting air flow so that the buoyancy force (p) at the rear vehicle body region against the situation shown in accordance with 1 is reduced (only 1 arrow instead of 3 arrows), or is reduced relative to the front vehicle body area, so that ultimately the contact forces of the rear vehicle wheels ( 1.2 ) opposite to the roadway ( 5 ) are again increased (the buoyancy force (p) resulting from the air flow is counteracted, or is partially or completely compensated).

When in the 2 and 3 shown sensors ( 4.2 ) may be force sensors and / or displacement sensors, which the contact forces of the rear wheels ( 1.2 ) to the carriageway ( 5 ) to capture. For example, the sensors ( 4.2 ) be designed as force sensors, which detect the contact force in a direct manner. Alternatively, the sensors ( 4.2 ) be designed as displacement sensors, which detect the contact force in an indirect manner by the Ausfederweg is evaluated as a measured variable (the larger the Ausfederweg, the lower the contact pressure of the wheels 1.2 to the roadway 5 ).

4 shows a representation of the operation of the method according to the invention. Like from the 4 As can be seen, in the method according to the invention a variation of the vehicle inclination angle (α) with respect to the roadway takes place above a certain speed (in this example from 100 km / h) ( 5 ). The variation of the angle of inclination (α) can in this case be continuous, or as not shown in detail in a stepped form, or non-linear form.

Like from the 4 rudimentary / illustrated in principle / idealized, the buoyancy force (p) increases with increasing vehicle speed, the increase of the vehicle speed-dependent buoyancy force (p), as a result of the resulting air flow, from 100 km / h is compensated by varying the inclination angle (α).

Furthermore, the shows 4 in the detailed view on the basis of the distance (b) parallel to the road ( 5 ) extending auxiliary line (c) that the vehicle inclination angle (α) to the road surface ( 5 ) Refers.

5 shows a representation of the operation of the method according to the invention with reference to a practical example. The upper illustration shows a sectional view of an aircraft wing. If the wing were to be moved in the right direction, then, as already mentioned, a force arises on the wing due to physical laws (Bernoulli effect), which pulls the wing upwards.

However, moving the wing in the left direction (direction of travel of the vehicle), as a result of physical laws on the wing, a force that pulls the wing down (presses).

The lower diagram shows by means of the superimposed on the vehicle representation dotted wing representation that means of method according to the invention, due to variation of the vehicle inclination angle (α), in a simple manner using physical laws (aircraft wing quasi in "reverse mode"), the contact pressure of the wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite the carriageway ( 5 ) in a simple way, can be set to a vorgebaren desired value. The for the contact pressure of the wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite the carriageway ( 5 ) required air flow is generated by the resulting "headwind", which results from the vehicle speed when the vehicle is driven forward in a forward gear.

Finally, it should be noted that the in 1 shown dotted line for representing the vehicle inclination (α), a fictitious reference line is to represent / describe a starting situation, or in the following 2 to 4 to be able to represent the variation of the vehicle inclination on the basis of the inclination angle (α).

LIST OF REFERENCE NUMBERS

1

Vehicle, in particular motor vehicle

1.1

Front vehicle wheel / vehicle wheel front

1.2

Rear vehicle wheel / rear vehicle wheel

2.1

Front vehicle axle / vehicle axle front

2.2

Rear vehicle axle / vehicle axle rear

3.0

Control unit for ventilating and venting the air spring bellows

3.1

Front air bag / air bag at the front

3.2

Rear air bag / rear air bag

3.3

Lines for ventilating and venting the air spring bellows

4.2

Sensor for the acquisition of measured quantities

4.3

signal line

5

Roadway, roadway to be driven

6

Sectional shape of an aircraft wing

p

buoyancy

a

distance

b

distance

c

Parallel to the carriageway ( 5 ) extending auxiliary line

α

Angle between vehicle inclination and roadway

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013008655 A1 [0006, 0007, 0013]

Claims (10)

Method for a vehicle chassis with air suspension system a) for setting a contact pressure, b) at least one vehicle wheel ( 1.1 . 1.2 ) of a vehicle axle ( 2.1 . 2.2 ) on the road to be traveled ( 5 ), c) an air-suspension vehicle ( 1 ), which has an air-sprung front axle ( 2.1 ) and an air-sprung rear axle ( 2.2 ), and d) in which a plurality of chassis elements of the chassis axles ( 2.1 . 2.2 ) and the vehicle body arranged air spring bellows ( 3.1 . 3.2 ) to control their actual level to a predetermined target level via designed as switching valves level control valves are ventilated and / or vented, characterized in that e) are used by the vehicle speed (v) dependent aerodynamic laws, f) to specifically a Change of a contact force of at least one vehicle wheel ( 1.1 . 1.2 ) of a vehicle axle ( 2.1 . 2.2 ) on the road to be traveled ( 5 ) to effect. Method according to Claim 1, characterized in that an increase in the contact forces of the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ) is effected by the vehicle body in the region of the rear axle ( 2.2 ) relative to the area of the front axle ( 2.1 ) is raised ( 2 ). Method according to Claim 1, characterized in that an increase in the contact forces of the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ) is effected by the vehicle body in the region of the front axle ( 2.1 ) relative to the region of the rear axle ( 2.2 ) is lowered ( 3 ). Method according to one of claims 1 to 3, characterized in that the raising and / or lowering of the vehicle body by ventilation and / or ventilation of the bellows ( 3.1 . 3.2 ) on the corresponding vehicle axles ( 2.1 . 2.2 ) is effected. Method according to one of claims 1 to 3, characterized in that at least in the region of the air-sprung rear axle ( 2.2 ), Sensors ( 4.2 ) are arranged to detect measured variables. Method according to one of claims 1 and 5, characterized in that by means of the sensors ( 4.2 ) directly and / or indirectly the contact forces of the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ). Method according to claim 6, characterized in that the sensors ( 4.2 ) are designed as force sensors or displacement sensors. Method according to one of claims 1 to 7, characterized in that the aerodynamic laws are used in such a way that by means of ventilation and / or ventilation of one or more air bellows ( 3.1 . 3.2 ) the vehicle speed-dependent buoyancy force (p) is changed due to the resulting air flow so as to reduce the buoyancy force (p) at the rear vehicle body region relative to the vehicle body front region. Method according to one of claims 1 to 8, characterized in that the buoyancy force (p) at the rear of the vehicle area by means of the sensors ( 4.2 ) and, depending thereon, by means of aeration and / or venting of one or more bellows ( 3.1 . 3.2 ) the vehicle inclination (α) is varied in such a way until a presettable target contact pressure force on the vehicle wheels ( 1.2 ) of the rear axle ( 2.2 ) opposite to the driving lane ( 5 ). Vehicle ( 1 ), in particular designed as a motor vehicle, provided with a chassis with air spring system, which functionally has a method according to one of the preceding claims.

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