Electronic control unit for a level control device of a vehicle, and method for ascertaining the axle load using such a control unit

Abstract

The invention relates to an electronic control unit (10) for an electronically regulated level control device (1) of a mechanically and / or pneumatically / hydraulically suspended vehicle, comprising control means which are designed to control the level and sensor means. The control means and sensor means are installed in the vehicle and / or are functionally expanded such that in addition to the level control or in lieu of the level control, functions can be added for ascertaining the axle load on mechanically suspended vehicle axles (4) and on pneumatically / hydraulically suspended vehicle axles (2). According to the invention, the control unit (10) has an electric interface (10a) which is designed to receive electric measurement signals from sensors (6a, 9a) of different sensor types that are suitable at least for ascertaining the axle load on mechanically suspended vehicle axles, and the control unit has a first non-volatile storage device (10b) for storing sensor-specific characteristic curves and a second non-volatile storage device (10b) for storing an algorithm for processing or reprocessing the measurement signals which are forwarded or processed using the interface (10a), wherein for each stored sensor type, the current axle load on the mechanically suspended vehicle axle (4) in question can be ascertained by correlating the respective measurement signal forwarded or processed via the interface (10a) with the characteristic curve stored for the respective sensor type.

Description

[0001] Electronic control unit of a level control device of a vehicle and method for axle load determination with such a control unit

[0002] The invention relates to an electronic control unit of an electronically controlled level control device of a mechanically and / or pneumatically / hydraulically sprung vehicle, comprising control means and sensor means provided for level control, which are installed and / or functionally expanded in the vehicle such that, in addition to or instead of level control, functions for determining axle loads on mechanically sprung vehicle axles and for determining axle loads on pneumatically / hydraulically sprung vehicle axles are available. Furthermore, the invention relates to a method for determining an axle load using such a control unit on a mechanically and / or pneumatically / hydraulically sprung vehicle, a correspondingly designed level control device, and a vehicle with such devices.

[0003] Determining the axle load on a vehicle serves to display and monitor its loading status. This is intended to prevent safety-threatening overloads and unfavorable weight distribution on the vehicle. The installation of overload indicators is already mandatory, or will become mandatory in the future, particularly in commercial vehicles. Therefore, weighing the vehicle at an external weighing station will no longer be sufficient to comply with legal requirements. Therefore, there is a growing need for simple and cost-effective on-board weighing systems, i.e., those built into the vehicle.

[0004] So-called on-board weighing systems are already known, such as the product Air-Weigh™, which can be installed in vehicles with steel suspension, air suspension, or mixed suspension. The disadvantage is that such devices are relatively expensive, separate installation systems with which a commercial vehicle can be equipped, but they are designed exclusively to determine the axle load and, in particular, cannot be integrated into an existing level control system. Two separate systems are then required for level control and axle load determination. One well-known level control system is the one described in the WABCO GmbH company brochure "ECAS in Motor Vehicles," 2nd edition.The modular ECAS (Electronically Controlled Air Suspension) system described in the 2007 edition has long been used in commercial vehicles such as trucks, buses, and trailers, as well as in passenger cars. This system already features advanced functions that can also be used to determine axle load, at least on air-sprung axles.

[0005] Such an electronically controlled air suspension system for level control in vehicles essentially consists of several adjustable air spring elements designed as supporting bellows, an electronic control unit that can be integrated into a data bus system (CAN), a travel measuring device for recording travel variables to determine the level, a control valve device for actuating the air spring elements, and an operating unit for the user. In commercial vehicles such as trucks and buses, this air suspension system enables level control to facilitate loading and unloading of a vehicle. Especially with trailers, a consistent body height and improved tire freewheeling can be achieved with any load. Furthermore, existing so-called lifting axles can be raised or lowered as needed.

[0006] Systems such as the aforementioned ECAS can have one or more pressure sensors assigned to the air suspension elements, using pressure measurements to determine the axle load on air-sprung axles. A method for determining a vehicle's axle load by measuring pressures in axle-side air spring bellows is described, for example, in DE 44 39 064 B4.

[0007] On mechanically sprung vehicle axles, height sensors, which are also often referred to as displacement sensors due to their measuring principle, are generally used to determine the axle load. Axle load determination is based on measuring the spring travel of a spring element by which a vehicle axle or individual vehicle wheels are spring-coupled to a vehicle body. The displacement sensor is generally located on the vehicle body near the vehicle axle whose axle load is to be measured. In one frequently used sensor type, the displacement sensor is connected to the relevant axle via a lever. The displacement sensor, designed as a rotational angle sensor, detects a rotational movement of the lever and can be used to determine the axle load. DE 10 2016 004 721 A1, for example, describes such a measuring device for measuring an axle load on a vehicle.

[0008] From the unpublished DE 10 2017 011 753.5, a method for determining an axle load on a mechanically and / or pneumatically / hydraulic-sprung vehicle is known. The axle load is determined using control and sensor means that are provided for an electronically controlled, pneumatic / hydraulic level control system, for example ECAS, and may be functionally expanded. First, a plausibility check is performed, based on which the level control system recognizes the respective suspension type (mechanical or pneumatic / hydraulic) of a vehicle axle. Subsequently, the corresponding function for determining the axle load is activated. In the known method, the axle load on a mechanically sprung vehicle axle is determined using a displacement measuring device. The axle load on a pneumatically / hydraulic-sprung vehicle axle is determined using a pressure measuring device.

[0009] What's not entirely optimal is that only measurement signals from displacement sensors are used to determine axle load on mechanically sprung vehicle axles. This known method is therefore not designed for axle load determination on mechanically sprung axles using sensors whose measuring principle is not based on measuring the deflection of the vehicle body. Furthermore, while a displacement sensor can reliably detect vehicle overload, a load display across the entire load range, especially in the low load range when the vehicle is only lightly loaded, is rather inaccurate.Against this background, the object of the invention was to provide an electronic control unit with which, on the one hand, at least one axle load determination can be carried out on mechanically suspended vehicles and, on the other hand, an axle load determination with the option of level control can be carried out on pneumatically / hydraulically suspended or mixed-suspension vehicles. The control unit should have expanded functionality with regard to the detection of a sensor signal for axle load determination on the mechanically suspended vehicle axles. A further object was to present a method for axle load determination using such a control unit. In particular, this control unit and this method should be suitable for use in a commercial vehicle.

[0010] The solution to this problem arises from the features of the independent patent claims, while advantageous embodiments and further developments of the invention can be found in the respective associated dependent claims.

[0011] The invention was based on the finding that an already available air spring level control system for vehicles essentially contains all the components required for an axle load measurement system, regardless of the vehicle's suspension type. Such a system can be adapted and expanded with relatively little effort to enable operation in axle load determination largely independent of the sensor type. This provides a highly versatile system for level control and axle load measurement on pneumatic / hydraulic, mechanical, or mixed-suspension vehicles.

[0012] To achieve the device-related problem, the invention is based on an electronic control unit of an electronically controlled level control device of a mechanically and / or pneumatically / hydraulically sprung vehicle, with control means and sensor means provided for level control, which are installed and / or functionally expanded in the vehicle in such a way that, in addition to or instead of level control, functions for axle load determination on mechanically sprung vehicle axles and for axle load determination on pneumatically / hydraulically sprung vehicle axles are available.

[0013] According to the invention, it is provided that the control unit has an electrical interface which is designed to receive electrical measurement signals from sensors of different sensor types, at least those suitable for determining the axle load on mechanically sprung vehicle axles, and that the control unit has a first non-volatile memory for storing sensor-specific characteristic curves and a second non-volatile memory for storing an algorithm for processing or further processing the sensor-specific measurement signals forwarded or processed via the interface, wherein the current axle load on a respective mechanically sprung vehicle axle can be determined for each stored sensor type by means of a correlation of the respective sensor-specific measurement signal forwarded or processed via the interface with the characteristic curve stored for the respective sensor type.

[0014] The term "mechanical suspension" typically refers to a steel suspension. In principle, a mechanical suspension can also comprise springs made of other materials, such as other alloys or fiber composites, instead of steel springs. Reference to steel-sprung axles is not intended to limit the invention to mechanical springs made of this material. Reference to air-sprung vehicle axles can be applied similarly to hydraulically sprung axles. A pneumatic / hydraulic suspension is understood to be a suspension that can be based either on air springs (pneumatic) or fluid springs (hydraulic).

[0015] As mentioned at the beginning, the term "ECAS" is an abbreviation for Electronically Controlled Air Suspension. The invention provides an integrated axle load measuring system that can determine the axle load on a vehicle's axles, regardless of whether the suspension is pneumatic / hydraulic or mechanical, and is not limited to a specific sensor type on the mechanical axles. The particular advantage of the invention is that the same electronic control unit can determine the axle load on a mechanically sprung axle not only using conventional displacement sensors, but also using load sensors. This enables the control unit, for example, to evaluate the signal from particularly sensitive and precise load sensors.

[0016] Accordingly, the invention proposes storing a calculation algorithm in a reserved, non-volatile memory area in an electronic control unit of an electronically controlled level control system of a mechanically and / or pneumatically / hydraulically sprung vehicle, for example, in an ECAS system. This calculation algorithm can calculate the axle load on a mechanically sprung axle from measurement data from a sensor, for example, a height sensor or a load sensor, depending on the sensor type. Thus, for example, a height sensor and / or a load sensor can be arranged on the respective axle. This makes this extended ECAS system suitable for vehicles with different suspension types and sensor types.

[0017] The control unit of an air suspension level control system is therefore expanded in such a way that, in addition to the already existing functions of level control on the air suspension and axle load determination on air-sprung axles as well as axle load determination on mechanically sprung axles with a travel sensor, axle load determination on mechanically sprung axles with a load sensor can now also be carried out with this control unit.

[0018] To enable the calculation algorithm to process the corresponding measurement data, an interface is provided that is designed to capture signals from various sensor types, all of which are suitable for determining the axle load on mechanically sprung axles. This common, i.e. sensor-type-independent, interface is particularly capable of capturing signals from both a height sensor and a load sensor and transmitting them to the control unit. Characteristic curves for various possible sensor types are stored in a non-volatile memory of the control unit. The calculation algorithm can then evaluate the sensor signal using the respective sensor-specific characteristic curve to determine the axle load.

[0019] According to a first development of the invention, the interface can be designed as a pulse-width modulation interface. The pulse-width modulation (PWM) method is particularly well suited for transmitting analog sensor measurements to an electronic control system and has already proven itself in this regard many times. Accordingly, the electrical sensor measurements from height sensors and / or load sensors generated on mechanically sprung vehicle axles can be acquired via the interface, either via electrical or optical cables or via a radio link, converted into PWM signals, and fed to the computing algorithm for further processing. The particular advantage of this is that the PWM signal is relatively insensitive to disruptive external influences, such as line-dependent voltage drops.

[0020] According to another embodiment, it can be provided that measurement signals from a sensor arranged on or associated with a mechanically sprung vehicle axle for determining the axle load can be detected by means of the interface, wherein the sensor is based on a measuring principle that operates with contact between the vehicle axle and the vehicle body or on a measuring principle that operates without contact between the vehicle axle and the vehicle body.

[0021] Accordingly, the electrical interface is largely independent of the sensor type and can interact with sensors in which the vehicle body is mechanically coupled to a mechanically sprung vehicle axle, as well as with sensors in which a transmitting device and a receiving device are arranged on the vehicle body and on a mechanically sprung vehicle axle. According to another embodiment of the electronic control unit, it can be provided that the interface can be used to detect measurement signals from a sensor designed as a load sensor for determining the axle load, which is arranged on or in the vicinity of a mechanically sprung vehicle axle.

[0022] Until now, displacement sensors were mostly used to determine axle loads on mechanically sprung vehicle axles, with the vehicle's deflection being converted into an axle load. This type of axle load determination is suitable for determining when the vehicle's maximum permissible axle load has been reached or exceeded and has proven effective. However, with a partial load, determining the axle load is relatively inaccurate due to the amount of deflection. Load sensors are more suitable for reliably and accurately determining the axle load and the total weight of the vehicle across the entire range from unloaded to fully loaded. According to the invention, the interface is suitable for receiving measurement signals from such sensors.

[0023] For axle load determination on mechanically sprung vehicle axles, well-known strain gauge load sensors can be considered. These are based on measuring a change in electrical resistance due to a load-dependent deformation of a component. Magnetic field load sensors are already in development. Such future load sensors could, for example, utilize effects based on a load-dependent change in the magnetic properties of a ferromagnetic component, as described, for example, in DE 10 2007 048 569 B4. The corresponding characteristic curves of such sensor types can already be stored in the control unit or can be stored in the future with little effort.

[0024] Furthermore, it can be provided that the interface can be used to capture measurement signals from a sensor designed as a displacement sensor for determining axle load, arranged on or in the vicinity of a mechanically sprung vehicle axle. Conventional displacement sensors can, of course, also be used to determine axle load. These can be based on a mechanical coupling of a rotation angle sensor between the vehicle body and the vehicle axle, with a measured distance between the vehicle body and the vehicle axle being converted into an axle load value using a level signal characteristic curve. It is also possible to use contactless displacement sensors, i.e., without a mechanical coupling between the vehicle axle and chassis, which operate with an electromagnetic transceiver, as described, for example, in DE 10 2015 002 167 A1.

[0025] To achieve the method-related problem, the invention is based on a method for determining an axle load on a mechanically and / or pneumatically / hydraulically sprung vehicle, in which the axle load is determined with the aid of an electronic control unit of an electronically controlled level control device of the vehicle, wherein control and sensor means provided for the level control are installed and / or functionally expanded in the vehicle in such a way that, in addition to or instead of a level control, functions for determining the axle load on mechanically sprung vehicle axles and for determining the axle load on pneumatically / hydraulically sprung vehicle axles are available.

[0026] According to the invention, this method provides that, in order to determine the axle load on a mechanically sprung vehicle axle, a measurement signal from such a sensor is recorded via an electrical interface of the control unit, which is designed to receive electrical measurement signals from sensors of different sensor types, at least those suitable for determining the axle load on mechanically sprung vehicle axles, and is evaluated using an algorithm stored in the control unit. First, the sensor type intended for determining the axle load on the mechanically sprung vehicle axle is preselected or determined, and then a characteristic curve stored for this recognized sensor type in a memory of the control unit is selected. Using this characteristic curve, an axle load is assigned to the respective measured value of the recorded measurement signal, and a corresponding axle load-dependent signal is output.

[0027] Accordingly, an existing control unit for a level control system such as ECAS can also be advantageously used for vehicle applications where the vehicle does not have air springs, i.e., no support bellows, control valves, or pressure sensors, or where the vehicle has not only air-sprung axles with these components, but also mechanically sprung axles without these components. The control unit's software is modified and expanded with a sensor-type-independent electrical interface so that the axle load can also be determined on these mechanically sprung axles. The control unit records measured values ​​from sensors installed on the mechanically sprung axles and converts them into axle load values ​​using a characteristic curve. Suitable sensors can be displacement sensors or load sensors.The type of sensor present on the mechanically sprung axles of the vehicle is preselected in the control unit and calibrated as required.

[0028] The method can be advantageously applied to both mechanically sprung and mixed-suspension vehicles. To avoid malfunctions, a plausibility check can be performed prior to determining the axle load on the mechanically sprung vehicle axles in vehicles with mixed suspension to distinguish between mechanically sprung and pneumatically sprung axles. For this purpose, for example, the presence of supporting bellows, pressure sensors, and associated valve devices on existing air-sprung vehicle axles can be verified.

[0029] It is advantageous if the procedure is repeated at specific intervals, or at least if the respective sensor signals are recorded several times over a predetermined period of time and time-averaged output signals are generated. This can increase the accuracy and reliability of the determined axle load values. At a minimum, the procedure should be performed every time the control unit of the level control system is switched on. This ensures the system's proper operational readiness.

[0030] Furthermore, the invention also relates to a level control device of a vehicle, which is constructed for level control and for axle load determination on mechanically and / or pneumatically / hydraulically sprung vehicle axles according to at least one of the features of the device claims and is operable to carry out a method according to the above-mentioned method or the method claim. Finally, the invention relates to a vehicle, such as a commercial vehicle or passenger car, with a level control device for level control and for axle load determination on mechanically and / or pneumatically / hydraulically sprung vehicle axles, which is constructed according to at least one of the device claims and is operable to carry out a method according to at least one of the method claims.

[0031] The invention will be explained in more detail below with reference to an embodiment shown in the accompanying drawing.

[0032] Fig. 1 shows a highly schematically simplified level control device which is designed for axle load determination and level control on a vehicle equipped with mechanically and pneumatically sprung axles, and

[0033] Fig. 2 is a flow chart of an embodiment of a method according to the invention for determining an axle load on a mixed-suspension vehicle according to Fig. 1.

[0034] The level control device 1 of a vehicle, for example an ECAS system, for example of a truck, shown in simplified form in Fig. 1, has two adjustable air spring elements 3a, 3b designed as supporting bellows for resiliently supporting a vehicle body (not shown) relative to a rear vehicle axle 2 designed as a drive axle. A front vehicle axle 4, on the other hand, is supported relative to the vehicle body by two steel spring elements 5a, 5b designed as helical compression springs, i.e., is mechanically sprung.

[0035] The pneumatically / hydraulically suspended rear vehicle axle 2, in this case with air suspension, is assigned a position measuring device 6 with a position sensor 6a for detecting position variables for level control, a pressure measuring device 7 with at least one pressure sensor 7a for detecting pressure values ​​for axle load determination on the air-suspended vehicle axle 2, and a control valve device 8 designed as a valve circuit with a control valve 8a, 8b designed as a solenoid valve for each air suspension element 3a, 3b. The control valve device 8 is switchably pneumatically connected to the air suspension elements 3a, 3b and has a compressed air connection (not further specified). The mechanically suspended front vehicle axle 4, in this case with steel suspension, is assigned an axle load measuring device 9 with an axle load sensor 9a for axle load determination on this axle 4.

[0036] In addition, an electronic control unit 10 is arranged between the vehicle body and the air-sprung vehicle axle 2 for evaluating the travel, axle load, and pressure measurements, as well as for controlling the air suspension elements 3a, 3b to adjust the ride height. The electronic control unit 10 has an electrical interface 10a designed to receive and transmit measurement signals from various sensor types. The interface 10a is particularly capable of detecting and further processing measurement signals from various sensor types, which may be located on the mechanically sprung vehicle axle 4 depending on the vehicle's equipment. For this purpose, the interface 10a can be used to pulse-width modulate the received measurement signals, after which the modulated measurement values ​​are fed to the control unit 10.Furthermore, the electronic control unit 10 has a non-volatile memory 10b in which several characteristic curves of different sensor types are stored, for example in tables or value pairs.

[0037] In addition, an operating unit 11 for a respective user is electrically connected to the control unit 10. Using the operating unit 11, the user can initiate or perform settings and calibration of the level control device 1, for example as described in EP 2 097 278 B1. The control valve device 8, the position measuring device 6, and the pressure measuring device 7 assigned to the air-sprung axle 2, as well as the axle load measuring device 9 assigned to the mechanically sprung axle, are signal-connected to the control unit 10. The control unit 10 has a CAN controller, via which the control unit 10 is connected to a CAN bus 12. The CAN controller controls interrupt requests and regulates data transfer. The structure of a CAN bus in a vehicle and the connection of various bus participants to the CAN bus are known.

[0038] The travel sensor 6a for level control is attached to the vehicle body near its associated air-sprung vehicle axle 2 and connected to the vehicle axle 2 via a lever system (not shown). The travel sensor 6a has a rotation angle sensor (not shown), which detects the respective angular position of the aforementioned lever system. The rotational movement of the lever system can be converted into a linear movement inside the travel sensor 6a, for example, in the form of an armature immersing itself in a coil. As the ferromagnetic armature immerses itself in the stationary coil, a travel-dependent phase shift between current and voltage occurs, which is provided as an output signal to the control unit 10. From this signal, an actual level of the distance between the vehicle axle 2, 4 and the vehicle body can be determined.The value of the actual level can be used for level control on the air-sprung vehicle axle 2.

[0039] Level control of an air suspension with such a system is known per se. The travel sensor 6a for level control measures the distance between the vehicle axle and the vehicle body at specific intervals. The measured value determined is the actual value of a control loop and is forwarded to the control unit 10. In the control unit 10, this actual value is compared with a setpoint value defined in the control unit 10. If there is an unacceptable difference between the actual value and the setpoint value, the control unit 10 transmits a control signal to the control valve 8a, 8b. Depending on this control signal, the control valve 8a, 8b now controls the air spring element 3a, 3b designed as a bellows and inflates or deflates it. The pressure change in the air spring element 3a, 3b also changes the distance between the vehicle axle and the vehicle body. The distance is again measured by the travel sensor 6a and the cycle begins again.

[0040] The axle load sensor 9a for determining the axle load on the mechanically sprung vehicle axle 4 is attached to the vehicle body near its associated vehicle axle 4. The axle load sensor 9a can, for example, be designed as a displacement sensor, which is essentially identical in construction to the displacement sensor 6a for level control. On the mechanically sprung vehicle axle 4, with such an axle load sensor 9a, the value of the actual level is used to determine the axle load. The axle load determination on the mechanically sprung vehicle axle 4 makes use of the simple relationship that the force acting on the vehicle axle 4 is determined from the spring constant of the spring element 5a, 5b and the measured deflection, whereby the axle load of the vehicle can be determined using a level signal characteristic curve. This embodiment of an axle load sensor 9a is only to be seen as an example.Alternatively, axle load sensors 9a can be considered, which directly generate a load-dependent signal instead of a position-dependent signal. Such axle load sensors 9a are already known and are constantly being further developed.

[0041] According to the invention, the interface 10a of the control unit 10 is designed such that, as a common interface, it can process both signals from displacement sensors and signals from load sensors generated on mechanically sprung vehicle axles. All that is required is an algorithm that, using a stored sensor-specific characteristic curve, converts the measurement signal from the sensor detected by the control unit 10 into an axle load value.

[0042] Furthermore, the control unit 10 can receive additional signals from the pressure measuring device 7 via the interface 10a in order to determine the axle load on the air-sprung vehicle axle 2. The axle load determination takes advantage of the fact that the pressure value in the air spring element 3a, 3b can be used to determine the force acting on the vehicle axle 4, whereby an axle load value of the vehicle can be determined using a pressure signal characteristic curve.

[0043] Level control of an air suspension with such a system is not relevant to the invention per se and does not need to be described in detail here. The following explanation is therefore limited to the sequence of a method according to the invention for determining an axle load on the one hand on the mechanically sprung vehicle axle 4 and on the other hand on the air-sprung vehicle axle 2. Fig. 2 serves to explain this method. Accordingly, Fig. 2 shows a flowchart with function blocks F1 to F21 of method steps for determining an axle load on the air-sprung vehicle axle 2 and on the mechanically sprung vehicle axle 4.

[0044] The method starts with the activation of the level control device 1, for example when the vehicle's ignition system is switched on according to a first function block F1. First, an axle-specific plausibility check is carried out with three component queries, based on which the program is divided into two program branches. These are a first routine that determines the axle load on the air-sprung vehicle axle 2 and a second routine that determines the axle load on the mechanically sprung vehicle axle 4. An axle-specific plausibility check for identifying the type of suspension and a first routine for determining the axle load on an air-sprung vehicle axle are already described in the applicant's aforementioned DE 10 2017 011 753.5. In contrast, an adapted plausibility check and a new second routine according to the invention are presented here, which determines the axle load on the mechanically sprung vehicle axle 4.

[0045] Accordingly, the plausibility check begins with a first query F2, whether a signal from a control valve 8a, 8b is non-zero within a predetermined period of time. This is followed by a second query F3, whether a signal from a displacement sensor 6a is non-zero within a predetermined period of time. Subsequently, a third query F4 is performed, whether a signal from a pressure sensor 7a is non-zero within a predetermined period of time. These queries are performed equally on each vehicle axle 2, 4 or their associated components.

[0046] If a control valve signal, a travel sensor signal, and a pressure sensor signal are present, the air-suspended vehicle axle 2 is detected in block F5, and the associated axle load determination routine starts in block F6. The pressure sensor signal is read in block F7. In block F8, the axle load on the air-suspended vehicle axle 2 is determined using a pressure signal characteristic curve stored in a memory 10b of the control unit 10 and transmitted to the CAN bus 12 in block F9.

[0047] The axle load information of the air-suspended vehicle axle 2 can be displayed to the driver via a display and / or used by other electronic control systems. If no travel sensor signal is detected despite a control valve signal being present, level control is not possible on the air-suspended vehicle axle 2 according to block F10.

[0048] If no pressure sensor signal is registered although a control valve signal and a travel sensor signal are present, no axle load measurement can be carried out on the air-suspended vehicle axle 2 according to block F11 and the routine on the air-suspended vehicle axle 2 ends in block F12.

[0049] If there is no control valve signal in block F2, but a position sensor signal in block F3 and no pressure sensor signal in block F4, the mechanically sprung vehicle axle 2 is detected in block F13 and the associated routine for determining the axle load starts in block F14. In block F15, the position sensor signal or angle sensor signal is read out. In block F16, the actual level is determined from this. In block F17, the axle load on the mechanically sprung vehicle axle 4 is determined using a level signal characteristic curve stored in the memory 10b of the control unit 10, in which the measured actual level is correlated with the axle load, or using an angle signal characteristic curve in which the measured angle of rotation of the angle sensor is correlated with the axle load. This is sent to block F18 on the CAN bus 12.

[0050] If there is no control valve signal in block F2 and no displacement sensor signal in block F3, according to the invention a further query is made in block F21 as to whether a signal from a load sensor is present within a predetermined period of time. If this is the case, the mechanically sprung vehicle axle 2 is detected in block F13 and the associated routine for determining the axle load starts in block F14. The load sensor signal is read out in block F15a. In block F17a, the axle load on the mechanically sprung vehicle axle 4 is determined using a load signal characteristic curve stored in the memory 10b of the control unit 10, in which the measured load signal is correlated with the axle load, and is sent on the CAN bus 12 in block F18.

[0051] The axle load information for the mechanically suspended vehicle axle 4 can be shown to the driver via a display and / or used by other electronic control systems. Thus, the axle load information is available on all vehicle axles 2 and 4.

[0052] If neither a control valve signal nor a position sensor signal nor a load sensor signal is detected, the routine ends in block F19. If a pressure sensor signal is also detected when a position sensor signal is present, even though no control valve signal is present, an error has occurred and the routine ends in block F20.

[0053] The procedure routines can be performed on any number of vehicle axles for mechanically, pneumatically / hydraulicly, or mixed-suspension vehicles. List of reference symbols (part of the description)

[0054] 1 level control device

[0055] 2 Pneumatic / hydraulic suspended vehicle axle

[0056] 3a First air spring element

[0057] 3b Second air spring element

[0058] 4 Mechanically sprung vehicle axle

[0059] 5a First steel spring element

[0060] 5b Second steel spring element

[0061] 6 Position measuring device

[0062] 6a Sensor, displacement sensor of the displacement measuring device

[0063] 7 Pressure measuring device

[0064] 7a Sensor, pressure sensor of the pressure measuring device

[0065] 8 Control valve device, valve circuit

[0066] 8a First control valve of the valve circuit

[0067] 8b Second control valve of the valve circuit

[0068] 9 Axle load measuring device

[0069] 9a Sensor, axle load sensor of the axle load measuring device

[0070] 10 Electronic control unit

[0071] 10a Electrical interface of the control unit

[0072] 10b First non-volatile memory of the control unit

[0073] 10c Second non-volatile memory of the control unit

[0074] 11 Control unit operating unit

[0075] 12 CAN bus

[0076] F1 - F21 Function blocks of a control process

Claims

Patent claims:

1. Electronic control unit (10) of an electronically controlled level control device (1) of a mechanically and / or pneumatically / hydraulically sprung vehicle, with control means and sensor means provided for level control, which are installed and / or functionally expanded in the vehicle in such a way that, in addition to or instead of level control, functions for axle load determination on mechanically sprung vehicle axles (4) and for axle load determination on pneumatically / hydraulically sprung vehicle axles (2) are available, characterized in that the control unit (10) has an electrical interface (10a) which is designed to receive electrical measurement signals from sensors (6a, 9a) of different sensor types suitable at least for axle load determination on mechanically sprung vehicle axles,and that the control unit (10) has a first non-volatile memory (10b) for storing sensor-specific characteristic curves and a second non-volatile memory (10b) for storing an algorithm for processing or further processing the sensor-specific measurement signals forwarded or processed via the interface (10a), wherein for each stored sensor type, the current axle load on a respective mechanically sprung vehicle axle (4) can be determined by means of a correlation of the respective sensor-specific measurement signal forwarded or processed via the interface (10a) with the characteristic curve stored for the respective sensor type.

2. Control unit according to claim 1, characterized in that the interface (10a) is designed as a pulse width modulation interface.

3. Control unit according to claim 1 or 2, characterized in that by means of the interface (10a) measurement signals of a sensor (9a) arranged on a mechanically sprung vehicle axle (4) or assigned to the mechanically sprung vehicle axle (4) for determining the axle load can be detected, wherein the sensor (9a) is based on a measuring principle that requires contact of the sensor (9a) with the vehicle axle (4) and the vehicle body.

4. Control unit according to claim 1 or 2, characterized in that by means of the interface (10a) measurement signals of a sensor (9a) arranged on a mechanically sprung vehicle axle (4) or assigned to the mechanically sprung vehicle axle (4) for determining the axle load can be detected, wherein the sensor (9a) is based on a measuring principle which operates without contact between the vehicle axle (4) and the vehicle body.

5. Control unit according to one of claims 3 or 4, characterized in that by means of the interface (10a) measurement signals of a sensor (9a) arranged on or in the region of a mechanically sprung vehicle axle (4) and designed as a load sensor for determining the axle load can be detected.

6. Control unit according to one of claims 3 or 4, characterized in that by means of the interface (10a) measurement signals of a sensor (9a) arranged on or in the region of a mechanically sprung vehicle axle (4) and designed as a displacement sensor for determining the axle load can be detected.

7. Method for determining an axle load on a mechanically and / or pneumatically / hydraulically sprung vehicle, in which the axle load is determined with the aid of an electronic control unit (10) of an electronically controlled level control device (1) of the vehicle, wherein control and sensor means provided for the level control are installed and / or functionally expanded in the vehicle in such a way that, in addition to a level control or instead of a level control, functions for axle load determination on mechanically sprung vehicle axles (4) and for axle load determination on pneumatically / hydraulically sprung vehicle axles (2) are available, characterized in that for determining the axle load on a mechanically sprung vehicle axle (4) via an electrical interface (10a) of the control unit (10), which is designed to receive electrical measurement signals from sensors (6a, 9a) of different, at least designed for axle load determination on mechanically sprung vehicle axles of suitable sensor types, a measurement signal from such a sensor (6, 9a) is detected and evaluated by means of an algorithm stored in the control unit (10), wherein a) firstly the sensor type provided for axle load determination on the mechanically sprung vehicle axle (4) is preselected or determined, b) subsequently a characteristic curve stored for this detected sensor type in a memory (10b) of the control unit (10) is selected, c) with the aid of this characteristic curve an axle load is assigned to the respective measured value of the detected measurement signal, and d) a corresponding axle load-dependent signal is output.

8. Method according to claim 7, characterized in that in the case of a vehicle with mechanical and pneumatic / hydraulic mixed suspension, a plausibility check implemented in the electronic control unit (10) is first carried out, on the basis of which the level control device (1) recognizes the respective suspension type mechanical or pneumatic / hydraulic of a vehicle axle (2, 4), and then the corresponding function for determining the axle load is activated.

9. Level control device (1) of a vehicle, which is constructed for level control and axle load determination on mechanically and / or pneumatically / hydraulically sprung vehicle axles (2, 4) according to at least one of the device claims and is operable to carry out a method according to at least one of the method claims 10. Vehicle, in particular a commercial vehicle or passenger car, with a level control device (1) for level control and for axle load determination on mechanically and / or pneumatically / hydraulically sprung vehicle axles (2, 4), which is constructed according to at least one of the device claims and is operable to carry out a method according to at least one of the method claims.

Images