Sensor assembly of an air suspension device for a vehicle

Abstract

The present invention relates to a sensor assembly (1) for an air suspension device of a vehicle, the air suspension device having changeover valves (14) for air springs (8a, 8b) respectively for one axle (2) or a plurality of adjacent tandem axles, and shut-off valves (16a, 16b) for the air springs of each wheel (4a, 4b) of the axle (2) or for the air springs on each vehicle side of the tandem axle, and wherein the respective changeover valves (14) and shut-off valves (16a, 16b) are structurally combined in a valve body (12) arranged remote from the air springs (8a, 8b), wherein the air suspension device respectively has pressure sensors (18a, 18b) for measuring the bellows pressure in the bellows (10a, 10b) of the air springs (8a, 8b), the pressure sensors being arranged inside or on the valve body (12), and wherein the pressure sensors are respectively connected to connection lines (32a, 32b) of one bellows of one air spring assigned to them or of a plurality of bellows of a plurality of air springs assigned to them at the outlet of the assigned shut-off valves (16a, 16b). In order to be able to measure the bellows pressure (p B ) in the bellows as accurately as possible even in the case of this disadvantageous arrangement of the pressure sensors (18a, 18b), the pressure sensors are respectively connected to the connection lines of one bellows of one air spring assigned to them or of a plurality of bellows of a plurality of air springs assigned to them by filter assemblies (42a, 42b) acting as low-pass filters.

Description

Technical Field

[0001] The present invention relates to a sensor assembly for an air suspension device of a vehicle, the air suspension device having changeover valves for air springs each for one axle or for a plurality of adjacent tandem axles, and shut-off valves for the air springs of each wheel of an axle or for the air springs of each vehicle side of a tandem axle, and wherein the respective changeover valves and shut-off valves are structurally combined in a valve body arranged remote from the air springs, wherein the air suspension device respectively has pressure sensors for measuring the bellows pressure in the bellows of the air springs, the pressure sensor assembly being in or on the valve body, and wherein the pressure sensors are respectively connected to the connection lines of one bellows of one air spring assigned to them or of a plurality of bellows of a plurality of air springs assigned to them at the outlet of the associated shut-off valve. Background Art

[0002] An air suspension device of a vehicle usually has changeover valves for air springs each for one axle or for a plurality of adjacent tandem axles, which are preferably configured as 3 / 2 electromagnetic changeover valves, and shut-off valves for the air springs of each wheel of an axle or for the air springs of each vehicle side of a tandem axle, which are preferably configured as 2 / 2 electromagnetic shut-off valves. The working pressure line can be alternately connected to an exhaust outlet or a pressure-guided reservoir line via the changeover valve. The two shut-off valves are, for example, connected to the working pressure line via a T-piece, via which the connection lines leading to one bellows of one compression spring assigned to them or to a plurality of bellows of a plurality of compression springs assigned to them can be alternately connected to the working pressure line or shut off relative to it.

[0003] In the state where the changeover valve is not actuated, i.e., not energized, the working pressure line is connected to the exhaust outlet and is thus pressureless. In the actuated state of the changeover valve, i.e., the energized state, the working pressure line is connected to the reservoir line and is thus under the reservoir pressure provided by the compressed air device. In the state where the shut-off valve is not actuated, i.e., the not-energized state, the shut-off valve is closed and the connection line is shut off relative to the working pressure line. In order to reduce the bellows pressure in one bellows of one air spring assigned to it or in a plurality of bellows of a plurality of air springs assigned to it, it is only necessary to open the relevant shut-off valve, whereby the respective one or more bellows are vented. On the other hand, in order to increase the bellows pressure in one bellows of one air spring assigned to it or in a plurality of bellows of a plurality of air springs assigned to it, it is necessary to actuate the changeover valve and open the relevant shut-off valve, so that the respective one or more bellows are filled with air.

[0004] To determine the height or level of the vehicle body relative to the axle, height or level sensors are arranged on each axle on both sides respectively, or in the case of adjacent tandem axles, on at least one of the tandem axles. The height or level sensors are connected to an electronic controller via sensor lines. To determine the diaphragm pressure in the diaphragm bellows of the air spring, a pressure sensor is coupled to the connection line of each diaphragm bellows of the axle, or in the case of a tandem axle, to the connection line of the diaphragm bellows on the vehicle side. This pressure sensor is connected to the electronic controller via a sensor line. Depending on the sensor signals of the height sensor and the pressure sensor and the target data predefined by the control program or manually input by the driver, the electronic controller drives and controls a switching valve and a shut-off valve via an electrical control line, so as to maintain or set a predefined height of the vehicle body by admitting or exhausting air to or from the diaphragm bellows of the relevant air spring.

[0005] The pressure sensor can be directly coupled to the respective connection lines adjacent to the air spring. The advantage is that, even in the case of dynamic pressure changes, the respective diaphragm pressures in the diaphragm bellows of the adjacent air springs can be measured substantially without distortion. However, the disadvantage of this decentralized arrangement of the pressure sensors is that long sensor lines are required, the assembly effort is increased, and the pressure sensors and their electrical plugs are exposed to dirt and splash water. The decentralized arrangement of the pressure sensors close to the air spring is known, for example, from the air suspension device described in DE 36 38 849 A1.

[0006] Alternatively, the pressure sensor can also be arranged away from the air spring in or on the respective valve bodies and coupled to the connection line at the outlet of the assigned shut-off valve. The advantage of this centralized arrangement of the pressure sensors is that short sensor lines are required, the assembly effort is smaller, and the position of the pressure sensors and their electrical plugs is largely protected from dirt and splash water. However, this arrangement away from the air spring has the disadvantage that the respective diaphragm pressures in the diaphragm bellows of the adjacent air springs are incorrectly detected by the pressure sensor, especially during dynamic pressure changes when the assigned shut-off valve is opened and closed. The centralized arrangement of the pressure sensors in the control block of the air suspension device, which also includes an electronic controller in addition to the control valve, is known, for example, from DE 195 46 324 C2. Summary of the Invention

[0007] Since it has not been possible so far to precisely control the admission and exhaust of air to the diaphragm bellows based on the sensorially detected air pressure, the object of the present invention is to provide a sensor assembly for an air suspension device of a vehicle of the above-described structure, with which the diaphragm pressure in the diaphragm bellows of the air spring can still be precisely determined.

[0008] This task is solved by a sensor assembly having the features of claim 1. Advantageous refinements of the method are defined in the dependent claims.

[0009] Accordingly, the present invention relates to a sensor assembly for an air suspension device of a vehicle, the air suspension device having switching valves for the air springs for one axle or a plurality of adjacent tandem axles, respectively, and shut-off valves for the air springs of each wheel of an axle or for the air springs of each vehicle side of a tandem axle, respectively, and wherein the respective switching valves and shut-off valves are structurally combined in a valve body arranged remote from the air springs, and wherein the air suspension device respectively has pressure sensors for measuring the diaphragm pressure in the diaphragm bellows of the air springs, the pressure sensors being arranged in or on the valve body, and wherein the pressure sensors are respectively connected to the connection lines of one diaphragm bellows of one air spring or of a plurality of diaphragm bellows of a plurality of air springs assigned to them at the outlet of the assigned shut-off valves.

[0010] According to the invention, it is provided in such a sensor assembly for solving the posed task that the pressure sensors are respectively connected to the connection lines of one diaphragm bellows of one air spring or of a plurality of diaphragm bellows of a plurality of air springs assigned to them via filter assemblies acting as low-pass filters.

[0011] By connecting the pressure sensors via the respective filter assemblies acting as low-pass filters to the connection lines of one diaphragm bellows of one air spring or of a plurality of diaphragm bellows of a plurality of air springs assigned to them, in particular pressure peaks and pressure fluctuations occurring due to the opening and closing of the assigned shut-off valves are damped and filtered out, such that the air pressure p detected by the connected pressure sensors S corresponds as closely as possible to the diaphragm pressure p of the diaphragm bellows of the assigned air spring B (p S = p B ).

[0012] The filter assemblies preferably each consist of a throttle element and a smaller pressure vessel, which are arranged in series with one another between the assigned connection line and the associated pressure sensor. The volume of the pressure vessel is smaller than the smallest possible volume of the respectively assigned diaphragm bellows.

[0013] In order to be able to precisely match the filter assemblies to the respective connection lines and to one diaphragm bellows of one air spring or to a plurality of diaphragm bellows of a plurality of air springs assigned to them, the throttle elements of the filter assemblies are preferably constructed to be adjustable in terms of their opening cross-section.

[0014] To achieve the intended effect as a low-pass filter, it is preferably provided that the throttle elements and the pressure vessels of the filter assemblies are dimensioned as follows: the maximum possible opening diameter d of the throttle elementDR_max The square of and the volume V of the pressure vessel DB The ratio of and the line diameter d of the assigned connection line AL The square of and the minimum possible volume V of one spring bellows of an assigned air spring or of a plurality of spring bellows of a plurality of assigned air springs B_min is at least as large as (d DR_max 2 / V DB ≥ d AL 2 / V B_min ). Description of the Drawings

[0015] The present invention will be explained in more detail below with reference to the embodiments shown in the drawings. In the drawings:

[0016] Figure 1 A schematic view of an air suspension device for an axle of a vehicle is shown, which has a centrally arranged pressure sensor;

[0017] Figure 2 A graph shows the bellows pressure of the bellows and the pressure curve over time of the pressure detected by the pressure sensor during the intake process; and

[0018] Figure 3 A schematic view of an air suspension device for an axle of a vehicle is shown, which has a sensor assembly according to the present invention. Detailed Description of the Invention

[0019] In Figure 1 The air suspension device 6 for an axle 2 of a vehicle schematically depicted therein includes: air springs 8a, 8b each having a spring bellows 10a, 10b for each wheel 4a, 4b of the axle 2; a valve body 12 having switching valves 14 configured as 3 / 2 electromagnetic switching valves and shut-off valves 16a, 16b each configured as 2 / 2 electromagnetic switching valves for the air springs 8a, 8b of each wheel 4a, 4b; and pressure sensors 18a, 18b each for measuring the bellows pressure in each spring bellows 10a, 10b of the air springs 8a, 8b. Here, the pressure sensors 18a, 18b are pressure-voltage sensors and form the sensor assembly 1'.

[0020] With the aid of a switching valve 14 connected to the electronic controller 34 via an electrical control line 36, the working pressure line 20 can be alternately connected to an exhaust outlet 24 provided with a muffler 26 or to a pressure-guided reservoir line 28. A storage container 30 is connected to the reservoir line 28 to store compressed air in the storage container under a reservoir pressure. By means of two shut-off valves 16a, 16b which are connected on the inlet side via a T-piece 22 to the working pressure line 20 and are each connected to the electronic controller 34 in terms of signal technology via electrical control lines 38a, 38b, the respective connecting lines 32a, 32b to the spring bellows 10a, 10b of the assigned air springs 8a, 8b can be alternately connected to the working pressure line 20 or shut off with respect to it.

[0021] In the state where the switching valve 14 is not actuated, i.e., not energized, the working pressure line 20 is connected to the exhaust outlet 24 and is thus pressureless. In the actuated state, i.e., the energized state of the switching valve 14, the working pressure line 20 is connected to the reservoir line 28 and is thus under the reservoir pressure in the storage container 30.

[0022] In the state where the shut-off valves 16a, 16b are not actuated, i.e., not energized, the shut-off valves are each closed, and the connecting lines 32a, 32b are shut off with respect to the working pressure line 20. In order to reduce the bellows pressure in the spring bellows 10a, 10b of the assigned air springs 8a, 8b, it is only necessary to open the relevant shut-off valves 16a, 16b so that the corresponding spring bellows 10a, 10b are vented. And in order to increase the bellows pressure in the spring bellows 10a, 10b of the assigned air springs 8a, 8b, it is necessary to switch the switching valve 14 and open the relevant shut-off valves 16a, 16b so that the corresponding bellows 10a, 10b are filled with air.

[0023] Pressure sensors 18a, 18b are arranged in or on the valve body 12 and are each connected to the connecting lines 32a, 32b of the spring bellows 10a, 10b of the assigned air springs 8a, 8b at the outlet of the assigned shut-off valves 16a, 16b. The pressure sensors 18a, 18b are connected to the electronic controller 34 via respective electrical sensor lines 40a, 40b.

[0024] As Figure 2 exemplarily shown in the diagram for the filling of the spring bellows 10a, 10b of the air springs 8a, 8b, the bellows pressure p B present in the relevant spring bellows 10a, 10b and the air pressure p SDuring the intake process, they deviate strongly from each other because pressure peaks and pressure fluctuations occur at the outlets of the associated shut-off valves 16a, 16b due to their opening and closing. Therefore, it has hitherto been impossible to precisely control the intake and exhaust of the bellows 10a, 10b of the air springs based on the air pressure p Figure 1 sensed by the sensor assembly 1' according to S .

[0025] To solve this problem, a sensor assembly 1 according to the invention is provided, which is schematically shown in Figure 3 for a corresponding air suspension device 6' for a vehicle axle 2. Now, the pressure sensors 18a, 18b are respectively connected via filter assemblies 42a, 42b acting as low-pass filters to the connection lines 32a, 32b of the bellows 10a, 10b of the assigned air springs 8a, 8b. The filter assemblies 42a, 42b each consist of a pneumatic throttle 44a, 44b and a smaller pressure vessel 46a, 46b, which are arranged in series between the assigned connection lines 32a, 32b and the associated pressure sensors 18a, 18b. Here, the volume of each pressure vessel 46a, 46b is smaller than the smallest possible adjustable volume of the assigned bellows 10a, 10b of the air springs 8a, 8b.

[0026] By connecting the pressure sensors 18a, 18b via their respective filter assemblies 42a, 42b acting as low-pass filters to the connection lines 32a, 32b of the bellows 10a, 10b of the assigned air springs 8a, 8b, the pressure peaks and pressure fluctuations that occur, in particular due to the opening and closing of the assigned shut-off valves 16a, 16b, are damped and filtered out, so that the air pressure p S measured by the connected pressure sensors 18a, 18b corresponds as closely as possible to the bellows pressure p B of the bellows 10a, 10b of the assigned air springs 8a, 8b.

[0027] The throttles 44a, 44b of the filter assemblies 42a, 42b are adjustable in terms of their opening cross-section, so that the filter assemblies 42a, 42b can be precisely dimensioned to match the respective connection lines 32a, 32b and the bellows 10a, 10b of the assigned air springs 8a, 8b. To achieve the desired effect as a low-pass filter, the throttles 44a, 44b and the pressure vessels 46a, 46b of the filter assemblies 42a, 42b are dimensioned as follows: the square of the maximum possible opening diameter d DR_max of the throttles 44a, 44b and the volume V DB of the pressure vessels 46a, 46b and the line diameter d ALThe square of and the minimum possible volume V of the spring bellows 10a, 10b of the assigned air springs 8a, 8b B_min is at least as large as the ratio (d DR_max 2 / V DB ≥ d AL 2 / V B_min ).

[0028] List of reference numerals

[0029] 1 Sensor assembly (according to the invention)

[0030] 1' Sensor assembly

[0031] 2 Axle

[0032] 4a, 4b Wheels

[0033] 6, 6' Air suspension device

[0034] 8a, 8b Air springs

[0035] 10a, 10b Spring bellows

[0036] 12 Valve body

[0037] 14 Changeover valve

[0038] 16a, 16b Shut-off valves

[0039] 18a, 18b Pressure sensors

[0040] 20 Working pressure line

[0041] 22 T-piece

[0042] 24 Exhaust outlet

[0043] 26 Muffler

[0044] 28 Reserve line

[0045] 30 Storage container

[0046] 32a, 32b Connecting lines

[0047] 34 Electronic controller

[0048] 36 Control line

[0049] 38a, 38b Control lines

[0050] 40a, 40b Sensor lines

[0051] 42a, 42b Filter assemblies

[0052] Throttle parts 44a, 44b

[0053] Pressure vessels 46a, 46b

[0054] Diameter d

[0055] d AL Diameter of the connection line

[0056] d DR Opening diameter of the throttle part

[0057] d DR_max Maximum possible opening diameter of the throttle part

[0058] Pressure p

[0059] p B Diaphragm pressure

[0060] p S Air pressure detected by sensing

[0061] Volume V

[0062] V B Volume of one or more bellows

[0063] V B_min Minimum possible volume of one or more bellows

[0064] V DB Volume of the pressure vessel

Claims

1. Air suspension device (6’) for a vehicle, the vehicle having - an axle (2) with wheels (4a, 4b) or - a plurality of adjacent tandem axles, wherein - the air suspension device (6’) has air springs (8a, 8b), which each have a spring bellows (10a, 10b) and are for each wheel (4a, 4b) on the axle (2) or for each vehicle side of the vehicle on the tandem axle, - the air suspension device respectively has - a changeover valve (14) for the air springs (8a, 8b) for the axle (2) or the tandem axle, and - shut-off valves (16a, 16b) for the air springs (8a, 8b) for each wheel (4a, 4b) of the axle (2) or for the air springs for each vehicle side of the tandem axle, - the respective changeover valve (14) and shut-off valves (16a, 16b) are structurally combined in a valve body (12) arranged remote from the air springs (8a, 8b), - the air suspension device (6’) respectively has pressure sensors (18a, 18b) for measuring the bellows pressure in the spring bellows (10a, 10b) of the air springs (8a, 8b), the pressure sensors being arranged inside or on the valve body (12), and - the pressure sensors (18a, 18b) are respectively connected to the connection lines (32a, 32b) of the spring bellows (10a, 10b) of the assigned air springs (8a, 8b) at the outlet of the assigned shut-off valves (16a, 16b), It is characterized in that the pressure sensors (18a, 18b) are respectively connected to the connection lines (32a, 32b) of the bellows (10a, 10b) of the assigned air springs (8a, 8b) through filter components (42a, 42b) acting as low-pass filters, wherein the pressure peaks and pressure fluctuations caused by the opening and closing of the assigned shut-off valves are damped and filtered out, so that the air pressure detected by the connected pressure sensors corresponds as much as possible to the bellows pressure p of the bellows of the assigned air spring B .

2. The air suspension device (6') according to claim 1, characterized in that The filter assemblies (42a, 42b) each consist of a throttle member (44a, 44b) and a pressure vessel (46a, 46b), the throttle member and the pressure vessel being arranged in series between the assigned connection lines (32a, 32b) and the associated pressure sensors (18a, 18b).

3. The air suspension device (6') according to claim 2, characterized in that, The volume of the pressure vessels (46a, 46b) is smaller than the smallest possible volume of the respective assigned spring bellows (10a, 10b).

4. The air suspension device (6') according to any one of claims 2 to 3, characterized in that The throttle members (44a, 44b) of the filter assemblies (42a, 42b) are constructed to be adjustable in terms of their opening cross-section.

5. The air suspension device (6') according to claim 2 or 3, characterized in that, The throttle elements (44a, 44b) and the pressure vessels (46a, 46b) of the filter assemblies (42a, 42b) are dimensioned in such a way that the square of the maximum opening diameter d of the throttle elements (44a, 44b) DR_max and the volume V of the pressure vessels (46a, 46b) DB and the ratio of the square of the line diameter d of the assigned connecting lines (32a, 32b) and the minimum volume V of the spring bellows (10a, 10b) of the assigned air springs (8a, 8b) AL are at least as large, i.e., d B_min DR_max 2 ² / V DB ≥ d AL 2 ² / V B_min .​

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