METHOD AND SYSTEM FOR MEASURING HEIGHT IN A VEHICLE

Abstract

Disclosed is a method for measuring height in a vehicle by determining a distance between a vehicle chassis and a vehicle axle or parts connected thereto. In the method, a first device (12) with a first transmitter (13) and a first receiver (14) and a second device (15) with a second transmitter (16) and a second receiver (17) interact. In particular, the first transmitter (13) produces an electromagnetic field, and the second receiver (17) detects the electromagnetic field. The second device (15) with the second transmitter (16) produces a signal from the detected field and transmits the signal, which correlates with the distance from the first transmitter (13) to the second receiver (17). The first device (12) with the first receiver (14) receives the signal. A system, an electronically controlled pneumatic suspension, an electronic control unit, and a vehicle are also disclosed.

Claims

1. A method for measuring height in a vehicle by determining a distance between a vehicle chassis and a vehicle axle or parts connected thereto, with a first device with a first transmitter and a first receiver and a second device with a second transmitter and a second receiver, said method comprising: producing by the first transmitter an electromagnetic field; detecting by the second receiver the electromagnetic field; producing by the second device with the second transmitter a signal from the electromagnetic field; transmitting by the second device with the second transmitter the signal, which correlates with the distance from the first transmitter to the second receiver; and receiving the signal by the first device with the first receiver.

2. The method as claimed in claim 1, wherein the electromagnetic field produced by the first transmitter is a field with a low frequency.

3. The method as claimed in claim 1, wherein the signal transmitted by the second transmitter is an electromagnetic signal in the high frequency range or in the ultrahigh frequency range.

4. The method as claimed in claim 1, wherein the second receiver detects the strength of the electromagnetic field.

5. The method as claimed in claim 1, wherein the first device produces a standardized output signal from the received signal and provides the standardized output signal.

6. The method as claimed in claim 1, wherein the second device with the second transmitter only transmits a signal if a change of the electromagnetic field has been detected by the second receiver.

7. The method as claimed in claim 1, wherein the signal transmitted by the second transmitter contains a sender ID.

8. A system for measuring height in a vehicle by determining the distance between the vehicle chassis and a vehicle axle or parts connected thereto, said system comprising a first device with a first transmitter and a first receiver and a second device with a second transmitter and a second receiver, which first and second devices interact to carry out the method as claimed in claim 1.

9. The system as claimed in claim 8, wherein the first device is associated with the vehicle chassis and is connected to an electrical network of the vehicle.

10. The system as claimed in claim 8, wherein the second device comprises a dedicated electrical power supply that is independent of an electrical power supply of the first device or of a power supply of the vehicle.

11. The system as claimed in claim 8, wherein an electrical power supply for one of the two devices is a lithium-ion battery.

12. The system as claimed in claim 8, wherein an electrical power supply for one of the two devices has a capacity of less than or equal to 10 Ah.

13. The system as claimed in claim 8, wherein an electrical power supply for one of the two devices has an output voltage of about 5.4 V or less.

14. The system as claimed in claim 8, wherein the two devices are attached to the vehicle outside of the pneumatic suspension bellows.

15. An electronically controlled pneumatic suspension for a vehicle, with a system as claimed in claim 8.

16. The pneumatic suspension as claimed in claim 15, comprising a manually actuated valve arrangement for raising and/or lowering a vehicle body/vehicle chassis.

17. The pneumatic suspension as claimed in claim 15, comprising a pneumatic suspension valve.

18. The pneumatic suspension as claimed in claim 15, comprising a pressure sensor for the measurement of the pressure prevailing within a pneumatic suspension bellows.

19. A vehicle with a pneumatic suspension as claimed in claim 15.

20. An electronic control unit for an electronically controlled pneumatic suspension as claimed in claim 15, comprising an interface for receiving the signal forwarded or further processed by the first device and with software for processing the signal.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0035] The invention is described in greater detail below with reference to the accompanying figures, in which:

[0036] FIG. 1 shows two devices for transmitting and receiving signals in a schematic representation, and

[0037] FIG. 2 shows a truck (motor vehicle) with the two devices according to FIG. 1.

DETAILED DESCRIPTION

[0038] With reference to the specific embodiment of the Figures, wherein like numerals generally indicate like parts throughout the several views, FIG. 2 shows a truck 10 that is equipped in a known manner with a pneumatic suspension that is not shown in detail and an associated control unit 11.

[0039] At least one system for measuring height in the truck 10 is installed in connection with the pneumatic suspension. The components of the system are a first device 12 with a first transmitter 13 and a first receiver 14 and a second device 15 with a second transmitter 16 and a second receiver 17. The devices 12, 15 are provided and equipped for transmitting and receiving and for signal processing.

[0040] The two devices 12, 15 are oriented towards each other and disposed adjacent to each other but spaced apart from each other, so that the transmission of electromagnetic signals is possible. In this case, the first device 12 is associated with a vehicle chassis, in particular mounted on a chassis frame. The second device 15 is typically associated with a vehicle axle and in particular mounted on an axle support. The arrangement is selected so that the first device 12 is mounted approximately vertically above the second device 15.

[0041] Using the two devices 12, 15, a height measurement or a measurement of the change of the distance between the vehicle chassis and the vehicle axle is carried out. The two devices 12, 15 are mounted in the region of a rear axle 18. Alternatively, the system is provided with the two devices 12, 15 twice, namely once on the left and once on the right on the rear axle 18. Yet further measurement points (systems) are possible, for example on a front axle.

[0042] The height measurement is carried out cyclically at short intervals, for example at intervals of 25 ms or less.

[0043] The first transmitter 13 contains an antenna and produces a low frequency alternating magnetic field of 125 kHz. In certain embodiments, the antenna is oriented towards the second device 15. The magnetic alternating field is oriented accordingly.

[0044] The second receiver 17 contains a receiving antenna with an electronic circuit for determining the field strength of the low frequency magnetic field. The associated capability of the circuit is referred to as an RSSI (Received Signal Strength Indication). RSSI is used inter alia in wireless networks according to the IEEE 802.11 Standard.

[0045] For the processing of the field strength determined by the second receiver 17, the second device 15 can comprise an electrical circuit that is known in connection with keyless vehicle access systems (keyless entry/go), for example NCF 2952 or NCF 2951 of the manufacturer NXP Semiconductors N. V.

[0046] The field strength determined cyclically by the second receiver 17, for example every 20 ms, correlates with the distance between the two devices 12, 15. Accordingly, changes of the distance can be determined from the change of the field strength. The magnitude of the field strength determined by the second receiver 17 is converted in the second device 15 into a high frequency (or ultra-high frequency) signal of preferably 433 or 868 MHz. Moreover, the signal is encoded and/or provided with a sender ID and transmitted by the second transmitter 16.

[0047] The first receiver 14 receives and checks (and encodes) the transmitted signal. In the first device 12, the received signal is converted into a standardized output signal. An interface 19 is provided in the first device 12 for this purpose.

[0048] Moreover, the first device 12 comprises an in particular multipole socket 20 for connecting a connecting line 21. The latter is connected for forwarding the output signal to the control unit 11 and thus connects the system for measuring height to the control unit 11.

[0049] The second device 15 is supplied with electrical energy by an installed long-life battery 22. In contrast, the first device 12 is connected via the line 21 to an on-board network, which is not shown, of the truck 10. The line 21 comprises at least three conductors, namely for ground, unit voltage and signal.

[0050] In the case of the arrangement of two systems on the rear axle, both are connected via lines to the control unit 11. The control unit can thus also detect and control a change in height on one side.

[0051] A whole series of advantages are linked to the described system. There are no mechanical parts present that can wear. No inaccuracies occur, such as can be caused by bearing play and/or the lateral deflection of a coupling rod. Additional connections are not necessary, preferably only the connection to a control unit. The material costs are low. A direct height measurement is carried out, i.e. the distance measurement is not dependent on a rotary motion, such as with a pivotable coupling rod. As a result, no sinusoidal distortion of the measurement values takes place. The provided devices can be installed directly on the vehicle chassis and on the vehicle axle at almost any locations. Installation in the pneumatic springs is not necessary. In the event of a fault, replacement can be carried out rapidly and inexpensively.