Electronic control unit for a level control device of a vehicle and method for determining an axle load using such a control unit

Abstract

The invention relates to an electronic control unit (10) for an electronically controlled level control device (1) of a mechanically and / or pneumatically / hydraulically suspended vehicle, comprising control means and sensor means provided for the level control. The control means and the sensor means are mounted and / or functionally expanded in the vehicle in such a way that, in addition to or instead of the horizontal adjustment, a function can be provided for ascertaining the axle load on the mechanically suspended vehicle axle (4) and for ascertaining the axle load on the pneumatically / hydraulically suspended vehicle axle (2). According to the invention, 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, which are at least suitable for ascertaining the axle load on the vehicle axle of the mechanical suspension, the control unit has a first non-volatile memory (10b) for storing a sensor-specific characteristic curve and a second non-volatile memory (10b) for storing an algorithm for processing or further processing a sensor-specific measurement signal forwarded or processed via the interface (10a), the sensor-specific measurement signal being transmitted or processed via the interface (10a) for each stored sensor type. According to the invention, the current axle load on the mechanically suspended vehicle axle (4) can be determined by means of the correlation of the respective sensor-specific measurement signals transmitted or processed via the interface (10a) with the characteristic curve stored for the respective sensor type.

Description

TECHNICAL FIELD

[0001] The invention relates to an electronic control unit for an electronic control of a level control device of a mechanically and / or pneumohydraulically suspended vehicle, which control unit has control means and sensor means provided for the level control, which are installed in the vehicle and / or functionally extended in such a way that, in addition to the level control or instead of the level control, a function for ascertaining the axle load on a mechanically suspended vehicle axle and for ascertaining the axle load on a pneumohydraulically suspended vehicle axle can be provided. Furthermore, the invention relates to a method for ascertaining the axle load on a mechanically and / or pneumohydraulically suspended vehicle using such a control unit, to a correspondingly configured level control device and to a vehicle having such a device. BACKGROUND

[0002] The ascertainment of the axle load on a vehicle is used to indicate and monitor the loading state of the vehicle. Thereby, it is intended to avoid a vehicle being overloaded, which is a threat to safety, and an unfavorable weight distribution. In particular in commercial vehicles, the installation of an overload indicator is already mandatory or will be mandatory in the future. Thus, the weighing of a vehicle at an external weighing station will not be sufficient to meet the legal requirements in the future. Thus, there is an increasing demand for simple and inexpensive vehicle-side, i.e. built-in, weighing systems.

[0003] So-called on-board weighing systems are known, for example the AirWeigh TM product, which can be built into vehicles with steel suspension, with air suspension or with hybrid suspension. The disadvantage is that such a device is a relatively expensive separate built-in system, which, although possible for commercial vehicles, is constructed only for the ascertainment of the axle load and cannot be integrated in particular into an existing level control device. Thus, two separate systems are required for level control and axle load ascertainment.

[0004] A known system for level control is, for example, the modularly constructed ECAS system (Electronically Controlled Air Suspension) described in the Firmenschrift der WABCO GmbH "ECAS im Motorwagen", 2. Ausgabe, 2007, which has been used in commercial vehicles (such as trucks, buses and trailer vehicles or passenger vehicles) for a long time. The system has an extended functionality with which the axle load can also be ascertained, at least on an air-suspended axle.

[0005] Such electronically adjusted air suspension arrangements for horizontal adjustment in vehicles are mainly composed of a plurality of adjustable air spring elements configured as load bellows, an electronic control unit which can be connected to a data bus system (CAN), a travel measuring device for detecting a travel variable for horizontal determination, a control valve device for actuating the air spring elements, and an operating unit for the user. In commercial vehicles, such as lorries and buses, the air suspension arrangement enables horizontal adjustment for facilitating the loading and unloading of the vehicle. In particular in trailer vehicles, a constant vehicle body height and an improved tire ground clearance can be achieved at each loading. In addition, it is also possible to raise or lower existing so-called lifting axles as required.

[0006] A system like the ECAS as mentioned can have one or more pressure sensors associated with the air spring elements, by means of which pressure measurement values the axle load on the air-suspended axle can be determined. For example, DE 44 39 064 B4 describes a method for determining the axle load of a vehicle by measuring the pressure in the air spring bellows on the axle side.

[0007] On mechanically suspended vehicle axles, the axle load is usually determined using height sensors, which are often also referred to as travel sensors on the basis of their measuring principle. Here, the axle load determination made is based on the measurement of the spring travel of the spring element by means of which the vehicle axle or the individual wheels are coupled to the vehicle body in a suspended manner. Here, the travel sensors are usually located on the vehicle body in the vicinity of those vehicle axles for which the axle load on the vehicle axle is to be measured. In the frequently used sensor type, the travel sensor is connected to the associated axle via a lever, wherein the rotational movement of the lever is detected by means of the travel sensor configured as a rotational angle sensor and the axle load is inferred therefrom. For example, DE 10 2016 004 721 A1 describes such a measuring device for measuring the axle load on a vehicle.

[0008] A method for vehicle-side acquisition of axle load on a mechanically and / or pneumohydraulically suspended vehicle is known from the unpublished DE 10 2017 011 753.5. The axle load is acquired by means of a control device and a sensor device which are provided for an electronically regulated pneumohydraulic level regulation system, for example an ECAS, and are functionally expanded if necessary. A plausibility check is first carried out, on the basis of which the level regulation system identifies the respective suspension type of the vehicle axle, mechanical or pneumohydraulic. The respective function for the acquisition of the axle load is then activated. In the known method, the acquisition of the axle load on a mechanically suspended vehicle axle takes place by means of a travel measurement device. The acquisition of the axle load on a pneumohydraulically suspended vehicle axle takes place by means of a pressure measurement device.

[0009] It is not ideal that only the measurement signal of a travel sensor is provided for the acquisition of the axle load on a mechanically suspended vehicle axle. This known method is therefore not suitable for acquiring the axle load on a mechanically suspended vehicle axle with sensors whose measurement principle is not based on the measurement of the vehicle body's lowering. Furthermore, although it is possible to reliably identify an overload of the vehicle by means of the travel sensor, the load indication is rather imprecise in the entire load range, in particular in the low load range when the vehicle is only lightly loaded. SUMMARY

[0010] Against this background, it is the task of the present application to provide an electronic control unit with the aid of which, while having the possibility of level regulation, it is possible to carry out the acquisition of the axle load on the one hand on a mechanically suspended vehicle and on the other hand on a pneumohydraulically or hybrid suspended vehicle. Here, the control unit should have extended functionality with regard to detecting sensor signals for the acquisition of the axle load on a mechanically suspended vehicle axle. It is a further task to propose a method for acquiring the axle load with such a control unit. In particular, the control unit and the method should be suitable for use in commercial vehicles.

[0011] The solution to this task is derived from the features of the independent claims, while advantageous design and refinement of the application can be gathered from the respectively assigned dependent claims.

[0012] The invention is based on the insight that an air spring-based level adjustment system for a vehicle already available as such has all the components required in principle for a vehicle axle load measuring system, more precisely not dependent on the type of suspension of the vehicle. This system can be adapted and expanded with relatively little outlay so that it can be operated in vehicle axle load acquisition largely independently of the sensor type. Thereby a system can be provided which can be used very widely for level adjustment and for vehicle axle load measurement on vehicles with pneumatic / hydraulic, mechanical or hybrid suspensions.

[0013] To solve the task on the device side, the invention is based on an electronic control unit of an electronically controlled level regulation device of a vehicle with mechanical and / or pneumatic / hydraulic suspension, which has control means and sensor means provided for level adjustment, which are installed in the vehicle and / or functionally expanded in such a way that a function for acquiring the vehicle axle load on a vehicle axle of a vehicle with mechanical suspension and for acquiring the vehicle axle load on a vehicle axle of a vehicle with pneumatic / hydraulic suspension can be provided in addition to the level adjustment or instead of the level adjustment.

[0014] According to the invention, it is provided that the control unit has an electrical interface which is configured for receiving electrical measurement signals from different sensor types which are suitable at least for acquiring the vehicle axle load on a vehicle axle of a vehicle with mechanical suspension, 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 algorithms for processing or further processing the sensor-specific measurement signals which are forwarded or processed via the interface, wherein for each stored sensor type, by means of the correlation of the respective sensor-specific measurement signal which is forwarded or processed via the interface with the characteristic curve stored for the respective sensor type, the current vehicle axle load on a vehicle axle of a vehicle with mechanical suspension can be acquired.

[0015] The term "mechanical suspension" is generally understood as steel suspension. In principle, instead of steel springs, the mechanical suspension can also have springs made of other materials, for example other alloys or fiber composite materials. When reference is made here to a vehicle axle with steel suspension, this is not to be understood as a restriction of the invention to mechanical springs made of this material. When reference is made to a vehicle axle with air suspension, this can correspondingly be transferred to a vehicle axle with hydraulic suspension. A pneumatic / hydraulic suspension is understood as a suspension which can either be based on air springs (pneumatic) or on liquid springs (hydraulic).

[0016] The name "ECAS" is used as an abbreviation for Electronically Controlled Air Suspension as already stated at the beginning.

[0017] By the present application an integrated axle load measuring system is provided, which can determine the axle load on the axles of a vehicle independent of a pneumatic / hydraulic or mechanical suspension and which is not limited here to a specific sensor type on a mechanical axle. A particular advantage of the present application is that the same electronic control unit can determine the axle load on a mechanical suspension not only by means of a conventional travel sensor, but also by means of a load sensor. Thereby, the control unit has the ability, for example, to evaluate the signal of a particularly sensitive and precisely measuring load sensor.

[0018] The present application thus proposes to store a calculation algorithm in the electronic control unit of the electronic level control of a mechanically and / or pneumatic / hydraulic suspended vehicle, for example in an ECAS system, in a predetermined non-volatile memory area, which calculation algorithm can calculate the axle load on a mechanically suspended axle from the measurement data of a sensor, for example a height sensor or a load sensor, depending on the construction type of the sensor. A height sensor and / or a load sensor can thus be arranged on the relevant axle. Thereby, such an expanded ECAS system is made suitable for vehicles with different suspension types and sensor types.

[0019] The control unit of an air spring type level control system is thus expanded in such a way that, in addition to the existing functions of level control on air suspensions and the acquisition of the axle load on the axles of air suspended vehicles and the acquisition of the axle load on mechanically suspended axles by means of travel sensors, the acquisition of the axle load on mechanically suspended axles by means of load sensors can now also be carried out by means of the control unit.

[0020] In order to make the calculation algorithm able to process the respective measurement data, an interface is arranged, which is configured to detect the signals of all sensor types suitable for the acquisition of the axle load on a mechanically suspended axle. This common, i.e. sensor type independent, interface is in particular able to detect the signals of height sensors and load sensors and to transmit them to the control unit. In the non-volatile memory of the control unit, a characteristic curve is stored for each of the sensor types considered. The calculation algorithm can then evaluate the sensor signals by means of the respective sensor-specific characteristic curve in order to acquire the axle load.

[0021] According to a first refinement of the application, it can be provided that the interface is configured as a pulse width modulation interface. Pulse width modulation (PWM) measures are particularly well suited for transmitting analog sensor measurements to an electronic control unit and have proven effective in this respect many times over. Thus, the electrical sensor measurements of height sensors and / or load sensors generated on a mechanically suspended vehicle axle can be selectively detected via an electrical line or an optical cable or via a radio link by means of the interface, converted into a PWM signal and delivered to a calculation algorithm for further processing. In this respect, it is of particular advantage that PWM signals are relatively insensitive to external interference influences, such as line-dependent voltage drops.

[0022] According to a further embodiment, it can be provided that measurement signals of sensors arranged on a mechanically suspended vehicle axle or assigned to the mechanically suspended vehicle axle can be detected by means of the interface for axle load acquisition, wherein the sensors are based on a measurement principle that works in contact with the vehicle axle and the vehicle body or on a measurement principle that works non-contact between the vehicle axle and the vehicle body.

[0023] Thus, the electrical interface is largely independent of the sensor type and can cooperate not only with sensors in which the vehicle body is mechanically coupled to the mechanically suspended vehicle axle, but also with sensors in which a transmitter and a receiver are arranged on the vehicle body and on the mechanically suspended vehicle axle.

[0024] According to a further embodiment of the electronic control unit, it can be provided that measurement signals of sensors configured as load sensors arranged on or in the region of the mechanically suspended vehicle axle can be detected by means of the interface for axle load acquisition.

[0025] Hitherto, axle load acquisition on a mechanically suspended vehicle axle has mostly been carried out using travel sensors, in which the vehicle's sag is converted into the axle load. This type of axle load acquisition is suitable for identifying when the maximum permissible axle load of the vehicle is reached or exceeded and has proven effective. However, in the case of partial loading, the axle load determination based on the height of the sag is relatively imprecise. In order to determine the axle load and the total weight of the vehicle reliably and precisely over the entire range from unloading to full loading, load sensors are more suitable. According to the application, the interface is suitable for receiving the measurement signals of such sensors.

[0026] Known strain-gauge load sensors are considered for example for the acquisition of the axle load on a mechanically suspended vehicle axle. These strain-gauge load sensors are based on the measurement of a resistance change as a result of a load-independent deformation of a component. Magnetic field load sensors are already in development. Such future load sensors can for example utilize the effect of a load-independent change in the magnetic properties of a component based on ferromagnetism, as described for example in DE 10 2007 048 569 B4. In the control unit, a corresponding characteristic curve of this sensor type can already be stored or in the future stored with little outlay.

[0027] It is additionally possible to provide that a measurement signal of a sensor arranged on or in the region of a mechanically suspended vehicle axle, which is configured as a travel sensor, can be detected by means of the interface for the axle load acquisition.

[0028] It goes without saying that conventional travel sensors can still be used for the axle load acquisition. These travel sensors can be based on a mechanical coupling between a rotation angle sensor between the vehicle body and the vehicle axle, wherein the measured distance between the vehicle body and the vehicle axle is converted into an axle load value by means of a level signal characteristic curve. It is also possible to use contactlessly operating travel sensors, i.e. without a mechanical coupling between the vehicle axle and the chassis, which operate with electromagnetic transmission and reception devices, as described in DE 10 2015 002 167 A1.

[0029] To solve the method-related task, the application is based on a method for the acquisition of an axle load on a mechanically and / or pneumatically / hydraulically suspended vehicle, in which method the axle load is acquired by means of an electronic control unit of an electronic level adjustment of the vehicle, wherein the control and sensor means provided for the level adjustment are installed and / or functionally expanded in the vehicle in such a way that, in addition to the level adjustment or instead of the level adjustment, a function for the acquisition of the axle load on a mechanically suspended vehicle axle and for the acquisition of the axle load on a pneumatically / hydraulically suspended vehicle axle can be provided.

[0030] According to the application, provision is made in the method that, in order to ascertain the axle load on a mechanically suspended vehicle axle, the measurement signals of the sensors are detected via an electrical interface of the control unit and evaluated by means of an algorithm stored in the control unit, the electrical interface being configured for receiving electrical measurement signals from sensors of different sensor types which are at least suitable for ascertaining the axle load on a mechanically suspended vehicle axle. Here, firstly the sensor type which is provided for ascertaining the axle load on a mechanically suspended vehicle axle is preselected or ascertained, and then the characteristic curve stored in the memory of the control unit for the sensor type identified is selected. By means of the characteristic curve, a respective measurement value of the measurement signals detected is assigned an axle load, and a corresponding axle load-dependent signal is output.

[0031] Thus, the existing control unit of a horizontal control device, such as an ECAS, can also advantageously be used in vehicle applications in which the vehicle does not have air springs, i.e. also no load bellows, control valves and pressure sensors, or in which the vehicle has not only air-suspended vehicle axles with these components, but also mechanically suspended vehicle axles without these components. The control unit is modified in terms of software and extended with a sensor-type-dependent electrical interface, so that the axle load on these mechanically suspended vehicle axles can also be ascertained by the control unit detecting the measurement values from the sensors installed on the mechanically suspended vehicle axles and converting them into axle load values by means of characteristic curves. Suitable sensors can be travel sensors or load sensors. For this purpose, the sensor type present on the mechanically suspended vehicle axles of the vehicle is preselected in the control unit, and calibration is carried out as required.

[0032] The method can advantageously be applied not only on mechanically suspended vehicles, but also on hybrid-suspended vehicles. In order to avoid functional faults, a plausibility check can be carried out in a vehicle with hybrid suspension before the axle load on the mechanically suspended vehicle axles is ascertained, in order to distinguish between mechanically suspended vehicle axles and pneumatically suspended vehicle axles. For this purpose, it is possible, for example, to check the presence of a load bellows, a pressure sensor and a valve device associated therewith on an existing air-suspended vehicle axle.

[0033] Advantageously, the method is carried out repeatedly within a certain time interval, or at least the respective sensor signals are detected a plurality of times within a predetermined period of time and an output signal averaged over time is formed therefrom. In this way, the accuracy and reliability of the axle load values ascertained can be improved. The method should at least be carried out after each reactivation of the control unit of the horizontal control device. In this way, perfect operational readiness of the system is ensured.

[0034] Furthermore, the invention also relates to a level control device for a vehicle, which is constructed according to at least one of the features mentioned in the apparatus claims, for the purpose of level adjustment and for the purpose of ascertaining the axle load on a vehicle axle with mechanical and / or pneumatic / hydraulic suspension, and which is designed to carry out the method according to the above-mentioned method or method claim. Finally, the invention relates to a vehicle, such as a utility vehicle or a passenger vehicle, which has a level control device for the purpose of level adjustment and for the purpose of ascertaining the axle load on a vehicle axle with mechanical and / or pneumatic / hydraulic suspension, which is constructed according to at least one of the apparatus claims and which is designed to carry out the method according to at least one of the method claims. BRIEF DESCRIPTION OF DRAWINGS

[0035] The invention is further explained below with reference to the embodiments shown in the drawings. Shown are:

[0036] Figure 1 A level control device, which is shown extremely schematically simplified, is constructed for axle load ascertainment and level adjustment on a vehicle with a vehicle axle equipped with mechanical and pneumatic suspension; and

[0037] Figure 2 A flow chart is shown of an embodiment of the method according to the invention, which is used for ascertaining the axle load on a vehicle with a hybrid suspension according to Figure 1 DETAILED DESCRIPTION

[0038] Figure 1 The level control device 1 (e.g. ECAS system) of a vehicle (e.g. truck) shown simplified in Fig. 1 has two adjustable and constructed as load-bearing bellows air spring elements 3a, 3b, which are used for suspension-like support of a not shown vehicle body relative to a rear vehicle axle 2 constructed as a driven axle. A front vehicle axle 4 is supported relative to the vehicle body via two steel spring elements 5a, 5b constructed as helical compression springs, i.e. mechanically suspended.

[0039] ​The rear vehicle axle 2, which is pneumatically / hydraulically suspended (here: air suspension), is assigned a travel measurement device 6 (which has a travel sensor 6a for detecting a travel variable for the level adjustment), a pressure measurement device 7 (which has at least one pressure sensor 7a for detecting a pressure value for ascertaining the axle load on the air-suspended vehicle axle 2) and a control valve device 8 (which has, for each air spring element 3a, 3b, a control valve 8a, 8b configured as a solenoid valve) configured as a valve circuit. The control valve device 8 is pneumatically connected in a switchable manner to the air spring elements 3a, 3b and has a compressed-air connection not further designated. The front vehicle axle 4, which is mechanically suspended (here: steel suspension), is assigned an axle load measurement device 9 having an axle load sensor 9a for ascertaining the axle load on the axle 4.

[0040] Furthermore, an electronic control unit 10 is arranged for evaluating the travel measurement values, the axle load measurement values and the pressure measurement values and for controlling the air spring elements 3a, 3b to adjust the ride level between the vehicle body and the air-suspended vehicle axle 2. The electronic control unit 10 has an electrical interface 10a configured for receiving and transmitting measurement signals of various sensor types. The interface 10a is in particular capable of detecting and further processing measurement signals from various different sensor types, which can be arranged on the mechanically suspended vehicle axle 4, depending on the vehicle configuration. For this purpose, a pulse width modulation of the received measurement signals can be performed by means of the interface 10a, and the modulated measurement values are then delivered to the control unit 10. Furthermore, the electronic control unit 10 has a non-volatile memory 10b in which a plurality of characteristic curves of various different sensor types are stored, for example in the form of tables or value pairs.

[0041] Furthermore, an operating unit 11 for the respective user is electrically coupled to the control unit 10. By means of the operating unit 11, the user can trigger or implement an adjustment and calibration of the level control device 1, for example as described in EP 2 097 278 B1. The control valve device 8, the travel measurement device 6 and the pressure measurement device 7 assigned to the air-suspended vehicle axle 2, and the axle load measurement device 9 assigned to the mechanically suspended vehicle axle are all connected in signal technology to the control unit 10. The control unit 10 has a CAN controller, via which the control unit 10 is coupled to a CAN bus 12. The CAN controller controls interrupt requests and regulates data transmission. The construction of a CAN bus in a vehicle and the connection of various bus participants to the CAN bus are known.

[0042] The travel sensor 6a for the level adjustment is fastened on the vehicle body in the vicinity of the air-suspended vehicle axle 2 to which it is assigned and is connected to the vehicle axle 2 via a not shown lever system. The travel sensor 6a has a not shown rotational angle sensor which detects the respective angular position of the lever system. The rotational movement of the lever system can be converted into a linear movement in the interior of the travel sensor 6a, for example in the form of an armature sinking into a coil, wherein in the sinking movement of the ferromagnetic armature into the fixed coil a travel-dependent phase shift between the current and the voltage is generated, which is provided as an output signal, which is acquired by the control unit 10. From this signal the actual level of the spacing between the vehicle axle 2, 4 and the vehicle body can be determined. On the air-suspended vehicle axle 2 the value of the actual level can be used for the level adjustment.

[0043] The level adjustment of air suspensions with such a system is known per se. The travel sensor 6a for the level adjustment detects the spacing between the vehicle axle and the vehicle body in certain time intervals. The measured values thus obtained are the actual values of the adjustment loop and are forwarded to the control unit 10. In the control unit 10 the actual values are compared with a target value which is fixedly set in the control unit 10. When there is an inadmissible difference between the actual value and the target value, an adjustment signal is forwarded by the control unit 10 to the control valves 8a, 8b. Depending on the adjustment signal, the control valves 8a, 8b now actuate the air spring elements 3a, 3b which are designed as bellows, and inflate or deflate the air spring elements. Due to the pressure change in the air spring elements 3a, 3b the spacing between the vehicle axle and the vehicle body also changes. The spacing is again detected by the travel sensor 6a and the cycle is restarted.

[0044] The axle load sensor 9a for the acquisition of the axle load on the mechanical suspension vehicle axle 4 is fastened on the vehicle body in the vicinity of the vehicle axle 4 to which it is assigned. The axle load sensor 9a can for example be designed as a travel sensor which is essentially identical in construction to the travel sensor 6a for the level adjustment. On the mechanical suspension vehicle axle 4 the value of the actual level is used in such an axle load sensor 9a for the axle load acquisition. Here the acquisition of the axle load on the mechanical suspension vehicle axle 4 takes place with the simple correlation that the force on the vehicle axle 4 is acquired from the spring constant of the spring element 5a, 5b and the measured sinking, from which the axle load of the vehicle can be determined by means of a level signal characteristic curve. This embodiment of the axle load sensor 9a is only considered exemplary. Alternatively thereto it is conceivable to consider an axle load sensor 9a which instead of generating a travel-dependent signal directly generates a load-dependent signal. Such axle load sensors 9a are already known and are constantly being developed.

[0045] According to the application, the interface 10a of the control unit 10 is designed at least such that it can process not only the signals of the travel sensors, but also the signals generated on the mechanically suspended vehicle axle by the load sensors as a common interface. Only one algorithm is required, which converts the measurement signals of the sensors recognized by the control unit 10 into axle load values by means of stored sensor-specific characteristic curves.

[0046] In addition, the control unit 10 can additionally receive the signals of the pressure measuring device 7 via the interface 10a in order to ascertain the axle load on the air-suspended vehicle axle 2. Here, the axle load is ascertained using the correlation that, from the pressure values in the air spring elements 3a, 3b, the force on the vehicle axle 4 can be inferred, from which the axle load value of the vehicle can be determined by means of a pressure signal characteristic curve.

[0047] The air-suspension level regulation with such a system is not essential to the application and is not described in detail here. Rather, the following statements are limited to the method flow according to the application for ascertaining the axle load on the mechanically suspended vehicle axle 4 on the one hand and the axle load on the air-suspended vehicle axle 2 on the other hand. Figure 2 The method is illustrated in the flowchart shown in Fig. 1, which has functional blocks F1 to F21 of method steps for ascertaining the axle load on the air-suspended vehicle axle 2 and the mechanically suspended vehicle axle 4. Figure 2 The flowchart shown in Fig. 1 has functional blocks F1 to F21 of method steps for ascertaining the axle load on the air-suspended vehicle axle 2 and the mechanically suspended vehicle axle 4.

[0048] The method begins with the activation of the level control device 1, for example upon switching on the vehicle ignition device according to the first functional block F1. A first axle-specific plausibility check is first carried out, which has three component queries on the basis of which the program is divided into two program branches. These are a first routine for determining the axle load on the air-suspended vehicle axle 2 and a second routine for determining the axle load on the mechanically suspended vehicle axle 4. The axle-specific plausibility check for identifying the type of suspension and the first routine for ascertaining the axle load on the air-suspended vehicle axle have already been described in the applicant's aforementioned DE 10 2017 011 753.5. Different from this is the matched plausibility check according to the application and the new second routine for ascertaining the axle load on the mechanically suspended vehicle axle 4, which are introduced here.

[0049] The plausibility check thus begins with the first query F2, i.e. whether there is a control valve 8a, 8b signal which is not equal to zero within a predetermined time period. This is followed by the second query F3, i.e. whether there is a travel sensor 6a signal which is not equal to zero within a predetermined time period. This is followed by the third query F4, i.e. whether there is a pressure sensor 7a signal which is not equal to zero within a predetermined time period. These queries are likewise carried out on each vehicle axle 2, 4 or the components assigned thereto.

[0050] If the control valve signal, the travel sensor signal and the pressure sensor signal are present, the air-suspended vehicle axle 2 is identified in block F5 and the routine for axle load acquisition assigned thereto is started in block F6. The pressure sensor signal is read in block F7. In block F8, the axle load present on the air-suspended vehicle axle 2 is acquired by means of the pressure signal characteristic curve stored in the memory 10b of the control unit 10 and transmitted on the CAN bus 12 in block F9.

[0051] The axle load information of the air-suspended vehicle axle 2 can be indicated to the driver by means of an indicator and / or used by other electronic regulating systems. If no travel sensor signal is detected, although a control valve signal is present, the level adjustment on the air-suspended vehicle axle 2 cannot be carried out according to block F10.

[0052] If, although a control valve signal and a travel sensor signal are present, no pressure sensor signal is recorded, the axle load measurement on the air-suspended vehicle axle 2 cannot be carried out according to block F11 and the routine on the air-suspended vehicle axle 2 ends in block F12.

[0053] If, in block F2, no control valve signal is present, however, in block F3 a travel sensor signal is present and in block F4 no pressure sensor signal is present, a mechanical-suspended vehicle axle 2 is identified in block F13 and the routine for axle load acquisition assigned thereto is started in block F14. The travel sensor signal or the rotation angle sensor signal is read in block F15. The actual level is thus determined in block F16. In block F17, the axle load present on the mechanical-suspended vehicle axle 4 is acquired by means of the level signal characteristic curve stored in the memory 10b of the control unit 10, in which the measured actual level is related to the axle load, or by means of the angle signal characteristic curve, in which the measured rotation angle of the rotation angle sensor is related to the axle load, and transmitted on the CAN bus 12 in block F18.

[0054] If neither the control valve signal is present in block F2 nor the travel sensor signal is present in block F3, a further inquiry is made in block F21 according to the application, i.e. whether a load sensor signal is present within a predetermined period of time. If this is the case, a mechanically suspended vehicle axle 4 is identified in block F13 and the routine for axle load acquisition belonging thereto is started in block F14. The load sensor signal is read in block F15a. In block F17a the axle load prevailing on the mechanically suspended vehicle axle 4 is acquired by means of a load signal characteristic curve stored in the memory 10b of the control unit 10, in which the measured load signal is related to the axle load, and is transmitted on the CAN bus 12 in block F18.

[0055] The axle load information of the mechanically suspended vehicle axle 4 can likewise be indicated to the driver via indicators and / or used by other electronic regulation systems. Thus, the axle load information is available on all vehicle axles 2, 4.

[0056] If neither the control valve signal nor the travel sensor signal nor the load sensor signal is detected, the routine ends in block F19. If, although the control valve signal is not present, the pressure sensor signal is also recorded in the presence of the travel sensor signal, an error is present and the routine ends in block F20.

[0057] The routine of the method can be carried out on any number of vehicle axles for mechanically, pneumatically / hydraulically or hybridally suspended vehicles.

[0058] List of reference signs (part of the description)

[0059] 1 horizontal control device

[0060] 2 pneumatically / hydraulically suspended vehicle axle

[0061] 3a first air spring element

[0062] 3b second air spring element

[0063] 4 mechanically suspended vehicle axle

[0064] 5a first steel spring element

[0065] 5b second steel spring element

[0066] 6 travel measuring device

[0067] 6a sensor, travel sensor of the travel measuring device

[0068] 7 pressure measuring device

[0069] 7a sensor, pressure sensor of the pressure measuring device

[0070] 8 control valve device, valve circuit

[0071] 8a first control valve of the valve circuit

[0072] 8b second control valve of the valve circuit

[0073] 9 axle load measuring device

[0074] 9a sensor, axle load sensor of the axle load measuring device

[0075] 10 electronic control unit

[0076] 10a electrical interface of the control unit

[0077] 10b first non-volatile memory of the control unit

[0078] 10c second non-volatile memory of the control unit

[0079] 11 operating unit of the control unit

[0080] 12 CAN bus

[0081] F1-F21 function blocks of the control method

Claims

1. An electronic control unit (10) for an electronically adjustable level control device (1) for a vehicle with mechanical and / or pneumatic / hydraulic suspension, the control unit having control means and sensor means provided for level control, the control means and sensor means being installed in the vehicle and / or functionally expanded so that, in addition to or instead of level control, a function for determining the axle load on a mechanically suspended vehicle axle (4) and a function for determining the axle load on a pneumatic / hydraulic suspended vehicle axle (2) can be provided, 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 for determining at least an axle load on a mechanically suspended vehicle axle (4). 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 algorithms for processing or further processing sensor-specific measurement signals forwarded or processed via the interface (10a). In this case, for each stored sensor type, the current axle load on a mechanically suspended vehicle axle (4) can be determined by correlation of the respective sensor-specific measurement signal forwarded or processed via the interface (10a) with a characteristic curve stored for the respective sensor type.

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

3. The control unit according to claim 1 or 2, characterized in that The interface (10a) can be used to detect a measurement signal of a sensor (9a) arranged on or associated with a mechanically suspended vehicle axle (4) for the purpose of determining the axle load, wherein the sensor (9a) is based on a measurement principle that requires the sensor (9a) to be in contact with the vehicle axle (4) and the vehicle body.

4. The control unit according to claim 1 or 2, characterized in that: The interface (10a) can be used to detect a measurement signal of a sensor (9a) arranged on or associated with a mechanically suspended vehicle axle (4) for the purpose of determining the axle load, wherein the sensor (9a) is based on a measurement principle that operates contactlessly between the vehicle axle (4) and the vehicle body.

5. The control unit according to any one of claims 3 or 4, characterized in that: The interface (10a) can be used to detect a measurement signal of a sensor (9a) arranged on or in the region of a mechanically suspended vehicle axle (4) and designed as a load sensor for axle load determination.

6. The control unit according to any one of claims 3 or 4, characterized in that: The interface (10a) can be used to detect a measurement signal of a sensor (9a) arranged on or in the region of a mechanically suspended vehicle axle (4) and designed as a travel sensor for axle load determination.

7. Method for determining axle loads on vehicles with mechanical and / or pneumatic / hydraulic suspension, wherein: The axle load is determined by means of an electronic control unit (10) of an electronically controlled level control device (1) of the vehicle, wherein control means and sensor means provided for level control are installed in the vehicle and / or functionally expanded so that, in addition to or instead of level control, functions for determining the axle load on a mechanically suspended vehicle axle (4) and for determining the axle load on a pneumatically / hydraulically suspended vehicle axle (2) can be provided, characterized in that In order to determine the axle load on a mechanically suspended vehicle axle (4), measurement signals of sensors (6, 9a) are detected via an electrical interface (10a) of the control unit (10) and evaluated with the aid of an algorithm stored in the control unit (10), the electrical interface being designed for receiving electrical measurement signals from sensors (6a, 9a) of at least different sensor types suitable for determining the axle load on a mechanically suspended vehicle axle, wherein: a) first preselecting or determining a sensor type which is provided for determining the axle load on a mechanically suspended vehicle axle (4), b) subsequently selecting a characteristic curve stored in a memory (10b) of the control unit (10) for the identified sensor type, c) assigning the axle load to the respective measured value of the detected measurement signal using the characteristic curve, and d) Output a corresponding axle load-dependent signal.

8. The method according to claim 7, characterized in that On vehicles with a mixed mechanical and pneumatic / hydraulic suspension, a plausibility check is first performed in the electronic control unit (10), based on which the level control device (1) identifies the respective suspension type of the vehicle axles (2, 4), i.e., mechanical or pneumatic / hydraulic, and subsequently activates the corresponding functions for axle load detection.

9. A level control device (1) for a vehicle, which is designed according to at least one of the device claims for level control and for determining the axle loads on a mechanically and / or pneumatically / hydraulically suspended vehicle axle (2, 4) and is operable for carrying out a method according to at least one of the method claims.

10. A vehicle, in particular a commercial vehicle or a passenger vehicle, having a level control device (1) for level adjustment and for determining axle loads on mechanically and / or pneumatically / hydraulically suspended vehicle axles (2, 4), the vehicle being constructed in accordance with at least one of the device claims and being operable for carrying out a method in accordance with at least one of the method claims.

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