阅读说明：本技术 用于获知机械和/或气动/液压悬挂的车辆上的车桥负荷的方法及其设备 (Method for determining the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle and device therefor ) 是由 英戈·约维斯 约翰·卢卡斯 于 2018-09-19 设计创作，主要内容包括：本发明涉及用于获知机械和/或气动/液压悬挂的车辆上的车桥负荷的方法。在此提出,借助设置用于电子调节的气动/液压式水平调节系统(1)的控制和传感机构来获知车桥负荷,其中,该控制和传感机构安装在车辆中和/或在功能上扩展在车辆中,使得附加于水平调节或替代水平调节地,还能提供用于获知机械悬挂的车桥(4)上的车桥负荷以及气动/液压悬挂的车桥(2)上的车桥负荷的功能,其中,借助位移测量装置(9)进行获知机械悬挂的车桥(4)上的车桥负荷,其中,借助压力测量装置(7)进行获知气动/液压悬挂的车桥(2)上的车桥负荷,并且其中,首先执行在水平调节系统(1)的电子控制单元(10)中实施的可信度检验,基于该可信度检验,水平调节系统(1)识别车桥(2、4)的各自机械或气动/液压悬挂方式,并随后激活相应的车桥负荷获知功能。本发明还涉及用于执行该方法的设备、适用于该方法的控制单元、相应构造的水平调节系统以及包括该设备的车辆。(The invention relates to a method for determining the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle. It is proposed that the axle load be determined by means of a control and sensor device of a pneumatic/hydraulic leveling system (1) provided for electronic control, wherein the control and sensor device is installed in the vehicle and/or functionally expanded in the vehicle such that, in addition to or instead of leveling, a function for determining the axle load on a mechanically suspended axle (4) and the axle load on a pneumatically/hydraulically suspended axle (2) can also be provided, wherein the determination of the axle load on the mechanically suspended axle (4) is performed by means of a displacement measuring device (9), wherein the determination of the axle load on the pneumatically/hydraulically suspended axle (2) is performed by means of a pressure measuring device (7), and wherein a plausibility check is performed first in an electronic control unit (10) of the leveling system (1), based on the plausibility check, the leveling system (1) identifies the respective mechanical or pneumatic/hydraulic suspension of the axles (2, 4) and subsequently activates the corresponding axle load detection function. The invention also relates to a device for carrying out the method, a control unit suitable for the method, a correspondingly configured level adjustment system and a vehicle comprising the device.)

1. Method for determining the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle, characterized in that the axle load is determined by means of a control and sensor device which is provided with a pneumatic/hydraulic leveling system (1) for electronic control, wherein the control and sensor device is installed in the vehicle and/or is functionally expanded such that, in addition to or instead of leveling, a function for determining the axle load on the mechanically suspended axle (4) and for determining the axle load on the pneumatically/hydraulically suspended axle (2) can be provided, wherein the axle load on the mechanically suspended axle (4) is determined by means of a displacement measuring device (9), wherein the axle load on the pneumatically/hydraulically suspended axle (2) is determined by means of a pressure measuring device (7), and wherein a plausibility check implemented in an electronic control unit (10) of the level control system (1) is first carried out, on the basis of which the level control system (1) identifies the respective mechanical or pneumatic/hydraulic suspension of the axles (2, 4) and subsequently activates the respective axle load detection function.

2. Method according to claim 1, characterized in that the plausibility check comprises a determination of the presence of a control valve device (8), a displacement measuring device (6, 9) and a pressure measuring device (7) on each axle (2, 4), wherein a mechanically suspended axle (4) is concluded if no control valve signal and no pressure sensor signal are present at the input or output to which the control unit (10) of the level control system (1) is assigned, or if the values of the control valve signal and the pressure sensor signal are zero within a predetermined time period of vehicle operation and if a displacement sensor signal or a value of the displacement sensor signal is non-zero, and if a plausible control valve signal and pressure sensor signal are present at the input or output to which the control unit (10) of the level control system (1) is assigned and if a displacement sensor signal or a value of the displacement sensor signal is present in a selective manner during vehicle operation Is non-zero for a predetermined period of time, it is concluded as a pneumatically/hydraulically suspended axle (2).

3. Method according to claim 1 or 2, characterized in that at least the following steps are performed:

-selecting and activating an axle load learning function on a mechanically suspended axle (4) based on the plausibility check,

-detecting an axle load-dependent distance between the associated axle (4) and the vehicle body by means of at least one displacement sensor (9, 9a) mounted at the axle (4) of the associated mechanical suspension, and ascertaining the actual level from the detected measurement signal,

-calculating the axle load on the mechanically suspended axle (4) from the actual level by means of a calculation algorithm evaluating at least one horizontal-axle load characteristic curve or a quantity derived from said characteristic curve, wherein the calculation algorithm is implemented in the electronic control unit (10) and the characteristic curve is stored in a memory of the control unit (10), and

-outputting and/or forwarding the learned axle load on the mechanically suspended axle (4) on a data bus (12) to an axle load indicating device, and outputting the learned actual level on the mechanically suspended axle (4) on the data bus in a selective manner.

4. Method according to claim 1 or 2, characterized in that at least the following steps are performed:

-selecting and activating an axle load learning function on a mechanically suspended axle (4) based on the plausibility check,

-detecting an axle load-dependent angle of a rod arrangement between the associated axle (4) and the vehicle body by means of a rotation angle sensor belonging to the displacement sensor (9, 9a), which rod arrangement connects the associated axle (4) to the vehicle body in an articulated manner,

-calculating the axle load on the mechanically suspended axle (4) as a function of the angle by means of a calculation algorithm evaluating at least one angle-axle load characteristic curve or a quantity derived from said characteristic curve, wherein the calculation algorithm is implemented in the electronic control unit (10) and the characteristic curve is stored in a memory of the control unit (10), and

-outputting the learned axle load on the mechanically suspended axle (4) on the data bus (12) and/or forwarding it to an axle load indicating device.

5. Method according to claim 1 or 2, characterized in that at least the following steps are performed:

-selecting and activating an axle load learning function on a pneumatically/hydraulically suspended axle (2) based on the plausibility check,

-detecting a pressure value related to the axle load by means of at least one pressure sensor (7, 7a) mounted on the axle (2) of the associated pneumatic/hydraulic suspension,

-calculating the axle load on the pneumatically/hydraulically suspended axle (2) from the pressure values by means of a calculation algorithm evaluating at least one pressure-axle load characteristic curve or a quantity derived from said characteristic curve, wherein the calculation algorithm is implemented in the electronic control unit (10) and the characteristic curve is stored in a memory of the control unit (10), and

-outputting the learned axle load value on the pneumatically/hydraulically suspended axle (2) on the data bus (12) and/or forwarding it to an axle load indicating device.

6. A method according to any one of claims 1 to 5, characterized in that the method is carried out repeatedly at certain time intervals, or that the respective sensor signals are detected a plurality of times at least within a predetermined time period, and that a time-averaged output signal is formed therefrom.

7. Device for determining the axle load on mechanically and/or pneumatically/hydraulically suspended vehicles, characterized in that an integrated axle load measuring system is arranged for a level control system (1) of a uniformly designed mechanically, pneumatically or hydraulically or hybrid suspended vehicle, said system having an electronic control unit (10) in which a calculation algorithm for a plausibility check is implemented in order to detect the respective suspension type of the axles (2, 4) and to calculate the axle load on these axles (2, 4) on the basis of sensor measurement signals detected at the axles (2, 4) and to compare the axle load with characteristic curves stored in a memory, wherein the control unit (10) of each mechanically suspended axle (4) is assigned at least one displacement sensor (9, b) mounted thereon, 9a) And wherein the control unit (10) of each pneumatically/hydraulically suspended axle (2) is assigned at least one pressure sensor (7, 7a) mounted on the respective axle (2).

8. Leveling system (1) of a vehicle, which is designed according to device claim 7 for leveling and axle load learning on mechanically and/or pneumatically/hydraulically suspended axles (2, 4) and which can be operated selectively or cumulatively for carrying out a method according to at least one of the method claims.

9. An electronic control unit configured to perform the method according to at least one of claims 1 to 6.

10. Vehicle, such as a commercial vehicle or a passenger vehicle, comprising a leveling system (1) which is designed according to the device claim 7 for leveling and axle load detection on mechanically and/or pneumatically/hydraulically suspended axles (2, 4) and which can be operated selectively or cumulatively for carrying out the method according to at least one of the method claims.

Technical Field

The invention relates to a method for determining the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle. The invention also relates to a device for carrying out the method, to a control unit suitable for carrying out the method, to a correspondingly designed level control system and to a vehicle having these devices.

Background

Knowledge of the axle load of the vehicle is used to indicate and monitor its load status. This avoids safety-critical overloading and an unfavorable weight distribution on the vehicle. In particular in commercial vehicles, overload indicators indicating overload have been forced or built in at a later date.

Electronically regulated air suspensions for level regulation in vehicles are also known to have an extended function of knowing the axle load on the axle of the air suspension. Such a system is, for example, the modular ECAS system (electrically controlled air suspension) described in company document "ECAS im Motorwagen" of WABCO GmbH (webber limited liability company), second edition, 2007, which has long been used for commercial vehicles such as trucks, buses and trailers, or also for passenger vehicles.

Such an electronic air suspension system is essentially composed of a plurality of adjustable air suspension elements in the form of bellows, an electronic control unit which CAN be integrated into a data bus system (CAN), a displacement measuring device for detecting displacement variables for a specific level, a control valve device for actuating the air suspension elements, and an operating unit for a user. In commercial vehicles such as trucks and buses, the air suspension system can be adjusted horizontally to facilitate loading or unloading of the vehicle. In particular in trailers, a constant body height and improved tire spin can be achieved with each load.

Such systems usually allow a selection of a plurality of switchable driving levels, i.e. a certain distance value from the vehicle body to one or more axles. In addition to the normal driving level, which can be specified by the vehicle manufacturer, other levels can be selected, for example for matching the height of the trailer, for improving stability at high speeds, or for saving fuel. By controlling the air suspension, the preset driving level can be automatically readjusted during driving. For this purpose, a comparison of the actual level with the target level is permanently performed during driving. If the actual level during driving is above the target level by a predetermined tolerance threshold in the positive or negative direction and is therefore currently outside the tolerance range for level adjustment, the control unit readjusts the actual level to the target level by actuating the valve circuit and correspondingly admitting/venting one or more bellows. If the target level preset value changes, the valve circuit is likewise actuated accordingly, wherein the transient state duration of the system is also taken into account.

Systems such as the ECAS described above may additionally have one or more pressure sensors, based on their measurements, which may, for example, operate a lift axle, adjust a starting aid, control the traction of the vehicle, or compensate for a tire pressure drop. When above or below the allowable axle load, a signal is sent to the control unit. However, these systems are only conceived for learning the axle load on an air-suspended axle, i.e. on a pneumatically or possibly hydraulically suspended axle, and not on a steel-suspended axle, i.e. on a mechanically suspended axle.

EP 2097278B 1 describes a method which can be used to calibrate the axle load indication of an ECAS level adjustment system by means of an operating unit. The method is provided for a commercial vehicle having a bellows suspension for pneumatic leveling.

DE 102013000874 a1 describes a method for indicating the axle load of a vehicle, wherein axle loads below an allowable maximum are indicated with different signals when the maximum is reached or exceeded, respectively. The method is intended to be carried out on an air-suspended vehicle.

In contrast, displacement sensors are used on mechanically suspended axles instead of pressure sensors to detect the axle load. Here, the knowledge of the axle load is based on the measurement of the suspension displacement of the suspension elements, whereby the axle or the individual wheel is spring-coupled to the vehicle body. The displacement sensor is typically located on the vehicle body near the axle whose axle load is to be measured. The displacement sensor is connected to the respective axle via a rod, wherein the rotational movement of the rod is detected by means of the displacement sensor in the form of a rotational angle sensor, and the axle load can be inferred therefrom.

DE 102016004721 a1 describes a measuring device for measuring the load on a vehicle axle, which has at least one mechanical suspension element by means of which the vehicle axle is spring-coupled to the vehicle body. The measuring device has a rotation angle sensor and a multi-arm gear train which converts the relative movement of the suspension elements into a rotational movement, which is measured by means of the rotation angle sensor. The force acting on the axle can be determined from the spring constant of the suspension element and the measured spring compression, from which the axle load of the vehicle can be determined.

In addition, on-board weighing systems are known, for example Air weighing^TMIt can be built into vehicles with different suspension systems or hybrid suspensions. But these are all separate devices that only know the axle load. Thus, additional systems such as ECAS are required for level adjustment.

Known axle load learning systems are either provided only for pneumatically/hydraulically suspended vehicles or only for mechanically suspended vehicles, or they are separate devices dedicated to vehicle weight learning without level adjustment. Therefore, sensors, measuring devices and control systems, or even two independent systems, associated with the system must be installed separately for different suspended vehicles and vehicles with or without leveling. In the future it will always be necessary to face the configuration of overload indicators for both types of suspension systems, which will increase the costs for the manufacturer, since the respective systems of both types must be further developed and maintained. For a hybrid-suspension vehicle which is itself of steel suspension and has one or more additional axles with air suspension, it is possible to additionally adjust the level of these additional axles, to measure and indicate the axle load on all axles and to adjust the vehicle level if necessary, which can result in particularly high costs.

Disclosure of Invention

Against this background, the object of the invention is to provide a method of the type mentioned above, by means of which, on the one hand, at least one axle load detection can be carried out for mechanically suspended vehicles and, on the other hand, axle load detection and possible level adjustment can be carried out for pneumatically/hydraulically suspended or hybrid suspended vehicles. Another task of the present invention is to propose a device that enables the method to be carried out using substantially uniform components, and that is also cost-effective to manufacture. In particular, the method and the device are suitable for use in commercial vehicles.

The solution of these objects is achieved by the features of the independent claims, while advantageous embodiments and improvements of the invention are to be found in the dependent claims.

The invention is based on the recognition that an air suspension level adjustment system for a vehicle is available which in principle has all the components required for an axle load measuring system, regardless of the type of suspension of the vehicle. Such a system can be matched or expanded with relatively little effort. This potentially saves the cost of an overload indicator in a pneumatic/hydraulic, mechanical or hybrid suspension vehicle.

In view of this, the invention firstly relates to a method for ascertaining the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle. In order to solve the problem of the method, the invention provides that the axle load is determined by means of a control and sensor device provided with a pneumatic/hydraulic leveling system for electronic leveling, wherein the control and sensor device is installed in the vehicle and/or is expanded in function, such that in addition to or instead of leveling, a function for determining the axle load on the mechanically suspended axle and a function for determining the axle load on the pneumatically/hydraulically suspended axle can be provided, wherein the axle load on the mechanically suspended axle is determined by means of a displacement measuring device, wherein the axle load on the pneumatically/hydraulically suspended axle is determined by means of a pressure measuring device, and wherein a plausibility check implemented in the electronic control unit of the leveling system is first carried out, on the basis of which plausibility check, the leveling system recognizes the respective mechanical or pneumatic/hydraulic suspension of the axle and subsequently activates the corresponding axle load detection function.

The term "mechanical suspension" is used to refer generally to steel suspensions. In principle, instead of a steel suspension, a mechanical suspension can have a suspension made of other materials (e.g. other alloys) or composite materials. If reference is made herein to a steel suspended axle, this is not intended to limit the invention to mechanical suspensions made of such materials. If an air-suspended axle is mentioned, it can be transferred to a hydraulically suspended axle accordingly. Pneumatic/hydraulic suspension refers to suspension that may be based on air suspension (pneumatic) or on liquid suspension (hydraulic).

The designation "ECAS" mentioned at the outset represents an abbreviation for Electronically regulated air Suspension (Electronically controlled air Suspension).

The present invention provides an integrated axle load measurement system that can ascertain the axle load on an axle independently of pneumatically/hydraulically or mechanically configured suspensions. The method according to the invention thus makes it possible to ascertain the axle load on mechanically, air or hybrid-suspended vehicles by means of a unified assembly based on known air suspension level control systems. The control unit of the air suspension leveling system is thereby expanded in terms of software technology in order to be able to use it to carry out axle load learning on a mechanically suspended axle in addition to the existing air suspension leveling and axle load learning functions of the air-suspended axle. Thus, the same control unit is able to measure axle loads, e.g. on steel-or air-suspended axles.

For this purpose, displacement sensors are used on mechanically suspended axles, on which usually horizontal adjustment is carried out, and on which usually axle load detection is carried out by means of pressure sensors. In this way, only the displacement sensor or pressure sensor provided for the air suspension leveling system is required for the purpose of ascertaining the axle load on the axle. In other words: knowing the axle load on the mechanically suspended axle does not require any new components, the same displacement sensors provided for the level adjustment of the air suspension level adjustment system can also be built for making the axle load knowledge on the mechanically suspended axle. Only the software of the control unit needs to be adapted.

Accordingly, in a vehicle equipped only with mechanically suspended axles, the knowledge of the axle load requires only the control unit of the air suspension level regulation system modified according to the invention and at least one displacement sensor of this system for each axle. In a hybrid-suspension vehicle, the control unit modified according to the invention and at least one displacement sensor for each mechanical suspension axle and, in the alternative, at least one pressure sensor for each air-suspended axle are also only required for the knowledge of the axle load. In an air-suspension-only vehicle, knowing the axle load can optionally not change the original control unit of the air suspension level regulation system, or a control unit modified according to the invention can be employed, together with the original at least one pressure sensor for each axle. Independently of this, the air suspension level control system on the air-suspended axle naturally performs its main level control function.

A particular advantage of the invention is that all vehicles use a unified system regardless of their suspension and whether or not they are provided with level adjustment. This has considerable cost saving potential. In particular, the costs for implementing the axle load measuring system and the overload indication for commercial vehicles of both suspension types are combined, as a result of which costs can be saved for the user of the vehicle equipped in this way and for the manufacturer of the vehicle.

In order to avoid functional faults and to invoke a corresponding correct function in the control unit for each axle, which knows the axle load on the axle, a plausibility check is provided. According to one embodiment of the invention, this can be done by simple component checking, i.e. the plausibility check includes determining whether a control valve device, a displacement measuring device and a pressure measuring device are present on the respective axle, wherein a mechanically suspended axle is concluded if no control valve signal and no pressure sensor signal are present at the input or output to which the control unit of the level control system is assigned, or if a displacement sensor signal or a non-zero value of the displacement sensor signal is present, and if a plausible control valve signal and a pressure sensor signal are present at the input or output to which the control unit of the level control system is assigned and if a displacement sensor signal is present in a selective manner, or if a non-zero value of the displacement sensor signal is present during a predetermined period of vehicle travel, an axle with pneumatic/hydraulic suspension is inferred.

As is known, in air suspension level regulation systems, there are generally installed control valves configured as solenoid valves for level regulation of the air-suspended axle by adjusting the pressure of a bellows; pressure sensors are also installed to learn the axle loads on these axles. If these components or their output signals are missing and additionally a displacement sensor signal is detected, it can be concluded that a mechanically suspended axle is present. In contrast, if the control valve signal and the pressure signal and possibly the displacement sensor signal are received, an air-suspended axle can be inferred. In practice, a displacement sensor is also present on the axle of a typical air suspension, since it is necessary for the horizontal adjustment. However, a displacement sensor on the air-suspended axle is not absolutely necessary for knowing the axle load itself.

According to one embodiment of the invention, the axle load learning function on a mechanically suspended axle may be performed by at least the following steps:

selecting and activating an axle load learning function on the mechanically suspended axle based on the plausibility check,

detecting an axle-load-dependent spacing between the associated axle and the vehicle body by means of at least one displacement sensor mounted at the axle of the associated mechanical suspension, and ascertaining an actual level from the detected measurement signal,

calculating the axle load on the mechanically suspended axle from the actual level by means of a calculation algorithm evaluating at least one horizontal axle load characteristic curve or a variable derived from the characteristic curve, wherein the calculation algorithm is implemented in an electronic control unit and the characteristic curve is stored in a memory of the control unit, and

-outputting the learned axle load on the mechanically suspended axle on the data bus and/or forwarding it to the axle load indicating device, and optionally outputting the learned actual level on the mechanically suspended axle on the data bus.

Hitherto, in conventional level adjustment systems, only displacement measurements of the axle have been carried out if there is also an air suspension above it. This coupling has now been eliminated. In accordance with the invention, the displacement measured by the displacement sensor can be converted into the axle load by means of a horizontal axle load characteristic curve both in the case of an air-suspended axle in which a bellows is present for height adjustment and in the case of a mechanically suspended axle in which a bellows and a control valve for the intake or exhaust of the bellows are not present, i.e. in the case of a mechanically suspended axle. By measuring the displacement of the mechanically suspended axle, the vehicle level at this axle can also be determined on the data bus and can be used as additional information, for example, in the level control function of the air-suspended axle.

Alternatively thereto, according to another embodiment of the invention, the axle load learning function on the mechanically suspended axle may be performed by at least the following steps:

selecting and activating an axle load learning function on the mechanically suspended axle based on the plausibility check,

detecting an angle of a rod arrangement between the associated axle and the vehicle body, which rod arrangement connects the associated axle to the vehicle body in an articulated manner, as a function of the axle load by means of a pivot angle sensor associated with the displacement sensor,

calculating the axle load on the mechanically suspended axle as a function of the angle by means of a calculation algorithm evaluating at least one angle-axle load characteristic curve or a variable derived from the characteristic curve, wherein the calculation algorithm is implemented in an electronic control unit and the characteristic curve is stored in a memory of the control unit, and

the axle load on the axle of the mechanical suspension is output and/or forwarded to the axle load indicating device.

Accordingly, the measured values of the pivot angle sensor for the lever mechanism between the axle and the vehicle body can be used as a direct output signal of the displacement sensor for axle load calculation from the angle-axle load characteristic curve. This makes it possible to detect and provide the axle load particularly quickly.

According to a further embodiment of the invention, the axle load learning function on a pneumatically/hydraulically suspended axle can be performed by at least the following steps:

selecting and activating an axle load learning function on the pneumatically/hydraulically suspended axle based on the plausibility check,

-detecting a pressure value related to the axle load by means of at least one pressure sensor mounted on the axle of the associated pneumatic/hydraulic suspension,

calculating the axle load on the pneumatically/hydraulically suspended axle as a function of the pressure values by means of a calculation algorithm evaluating at least one pressure-axle load characteristic or a variable derived from the characteristic, wherein the calculation algorithm is implemented in an electronic control unit and the characteristic is stored in a memory of the control unit, and

the known axle load value on the pneumatically/hydraulically suspended axle is output on the data bus and/or forwarded to an axle load indicating device.

Hereby, as mentioned before, an axle load learning function on a pneumatically/hydraulically suspended axle is advantageously provided. Only the plausibility check according to the invention is preceded.

Advantageously, the method is carried out repeatedly at certain time intervals, or at least detects the respective sensor signal a plurality of times within a predetermined time period, and thus forms an output signal averaged over time. This improves the accuracy and reliability of the known axle load value. The method should be performed at least after each renewed switching on of the control unit of the level adjustment system. This ensures that the system is ready for operation.

In order to solve the problem in terms of the device, the invention provides a device for detecting the axle load on a mechanically and/or pneumatically/hydraulically suspended vehicle. According to the invention, an integrated axle load measuring system is arranged in the device for a uniformly designed level control system of mechanically, pneumatically, hydraulically or hybrid-suspended vehicles, said system having an electronic control unit in which a calculation algorithm for a plausibility check is implemented in order to detect the respective suspension type of the axles and to calculate the axle loads on these axles on the basis of the sensor measurement signals detected at the axles and to compare them with characteristic curves stored in a memory, wherein the control unit of each mechanically suspended axle is assigned at least one displacement sensor mounted thereon, and wherein the control unit of each pneumatically/hydraulically suspended axle is assigned at least one pressure sensor mounted on the respective axle.

Accordingly, the control unit of the existing ECAS level regulation system can also be advantageously used for vehicle applications in which the vehicle does not have an air suspension, i.e. does not have a bellows, a control valve and a pressure sensor, or in which the vehicle does not only have an air-suspended axle with these components, but also has a mechanically suspended axle without these components. The control unit can likewise determine the axle loads on the mechanically suspended axles only by software modifications and extensions, by acquiring measured values from displacement sensors built into the mechanically suspended axles and converting them into axle load values.

If the signals from the pressure sensors and the control valves are not present on the axles, or the values of these signals are zero, the control unit will recognize the application. As described above, the axle load on the air-suspended axle is detected by means of the pressure sensor. In this way, the control unit will provide the axle load values of the air-suspended axle and/or the mechanically suspended axle according to the suspension design of the vehicle.

The invention therefore also comprises said electronic control unit, which is configured to carry out the method proposed by the invention.

Finally, the invention also relates to a leveling system which is designed according to the device claims for leveling and axle load detection on mechanically and/or pneumatically/hydraulically suspended axles and which can be operated selectively or cumulatively for carrying out a method according to at least one of the method claims, and to a vehicle, such as a commercial vehicle or a passenger vehicle, having such a leveling system.

Drawings

The invention will be described in detail hereinafter with reference to an embodiment shown in the drawings. In the figure:

FIG. 1 shows a highly simplified schematic diagram of a leveling system configured for axle load learning and leveling of a vehicle equipped with a mechanically and pneumatically suspended axle; and

fig. 2 shows a flow diagram of an embodiment of a method according to the invention for determining the axle load on a vehicle having a hybrid suspension according to fig. 1.

Detailed Description

The leveling system 1 of a vehicle, for example an ECAS system of a truck, shown in simplified form in fig. 1, has two adjustable air suspension elements 3a, 3b, which are designed as bellows for supporting a vehicle body (not shown) in a sprung manner relative to a rear axle 2, which is designed as a drive axle. In contrast, the front vehicle axle 4 is supported relative to the vehicle body via two steel suspension elements 5a, 5b, which are embodied as helical compression springs.

The rear axle 2 of the pneumatic/hydraulic suspension (air suspension in this case) is assigned: a first displacement measuring device 6 having at least one first displacement sensor 6a for detecting a displacement variable for level determination; a pressure measuring device 7 having at least one pressure sensor 7a for detecting pressure values for ascertaining an axle load on the vehicle axle 2; and a control valve device 8 configured as a valve circuit having a control valve 8a, 8b configured as a solenoid valve for each air suspension element 3a, 3 b. The control valve device 8 is connected in a pneumatically switchable manner to the air suspension elements 3a, 3b and has a compressed air connection (not shown in detail). A second displacement measuring device 9 is associated with the front axle 4 of the mechanical suspension (in this case a steel suspension), which has at least one second displacement sensor 9a for detecting the axle load on this axle 4.

Furthermore, an electronic control unit 10 is arranged for evaluating the measured displacement values and the measured pressure values and for controlling the air suspension elements 3a, 3b for adjusting the driving level between the vehicle body and the air-suspended axle 2. Also, an operation unit 11 for each user is electrically coupled to the control unit 10. The user can set up and calibrate the level adjustment system 1 at the operating unit 11, as described for example in EP 2097278B 1. The valve circuit 8 and the two displacement measuring devices 6, 9 and the pressure measuring device 7 are connected to a control unit 10 using signal technology. 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 the interrupt request and regulates the data transmission. The structure of the CAN bus in a vehicle and the connection of various bus participants to the CAN bus are known.

The first displacement sensor 6a and the second displacement sensor 9a are each fastened to the vehicle body in the vicinity of their associated axle 2, 4 and are connected to the axle 2, 4 via a respective rod system (not shown). The displacement sensors 6a, 9a each have a rotation angle sensor (not shown) which detects the respective angular position of the lever system. The rotary movement of the rod system can be converted into a linear movement within the displacement sensor 6a, 9a, for example in the form of an armature pull-in coil, wherein in the movement of pulling the ferromagnetic armature into the stationary coil a displacement-dependent phase shift is produced between the current and the voltage, which phase shift is supplied as an output signal to the control unit 10 for reception. From this signal, the actual level of the spacing between the respective axle 2, 4 and the vehicle body can be determined. On an air-suspended axle 2, the actual level value can be used for the level adjustment.

On a mechanically suspended axle 4, the actual level value is used to know the axle load, as described below. In this case, the determination of the axle load on the mechanically suspended axle 4 is carried out by means of a simple correlation, i.e. the force acting on the axle 4 is determined from the spring constants of the suspension elements 5a, 5b and the measured spring compression, so that the axle load of the vehicle can be determined by means of a simple characteristic curve. The axle load on the air-suspended axle 2 is not readily known by means of the displacement measuring device 6. The axle load on the air-suspended axle 2 is therefore usually determined by means of the pressure measuring device 7.

The use of such systems for leveling air suspensions is known per se. Typically, displacement sensors for leveling detect the spacing between the axle and the vehicle body at certain time intervals (e.g., every 100 ms). The known measured value is the actual value of the control loop and is forwarded to the control unit 10. In the control unit 10, the actual value is compared with the target value fixedly written in the control unit 10. When there is an impermissible difference between the actual value and the target value, the control unit 10 transmits a control signal to the solenoid valve. The solenoid valve operates the bellows to either intake or exhaust air in response to the control signal. The distance between the axle and the vehicle body is also changed by the pressure change in the bellows. The spacing is again detected by the displacement sensor and the cycle begins again.

The following exemplary embodiments are limited to the procedure of the method according to the invention for determining the axle load on the mechanically suspended axle 4 on the one hand and on the air suspended axle 2 on the other hand. Fig. 2 is used to illustrate the method. Accordingly, fig. 2 shows a flow chart of the method steps of functional blocks F1 to F20 for ascertaining the axle load on the air-suspended axle 2 and the mechanically suspended axle 4.

The method starts in a first functional block F1 with the level adjustment system 1 being activated, for example when the ignition of the vehicle is switched on. First, the axle reliability check is performed by a three-component query, whereby the program is split into two program branches. These are a first routine to determine the axle load on the air-suspended axle 2 and a second routine to determine the axle load on the mechanically-suspended axle 4.

The plausibility check starts with a first inquiry F2 of whether there is a non-zero signal from the control valve 8a, 8b within a predetermined period of time. Followed by a second inquiry F3 of whether there is a non-zero signal from the displacement sensor 6a, 9a within a predetermined time period. Followed by a third query F4 of whether there is a non-zero signal from the pressure sensor 7a within a predetermined period of time. These queries are performed equally for each axle 2, 4 or its associated components.

If the control valve signal, the displacement sensor signal and the pressure sensor signal are present, the air-suspended axle 2 is identified in block F5 and an associated routine for learning the axle load is started in block F6. In block F7, the pressure sensor signal is read. In block F8, the axle load on the air-suspended axle 2 is determined from the pressure-axle load characteristic curve stored in the memory of the control unit 10 and is transmitted on the CAN bus 12 in block F9.

The axle load information of the air-suspended axle 2 can be indicated to the driver by means of a display and/or can be used by other electronic regulating systems. If no displacement sensor signal is detected, no horizontal adjustment of the air-suspended axle 2 is carried out according to block F10, even if there is a control valve signal.

If no pressure sensor signal is recorded, no axle load measurement is taken of the air-suspended axle 2 according to block F11, even if there is a control valve signal and a displacement sensor signal, and the routine for the air-suspended axle 2 ends in block F12.

If the control valve signal is not present in block F2, the displacement sensor signal is not present in block F3 and the pressure sensor signal is not present in block F4, the mechanically suspended axle 2 is identified in block F13 and an associated routine for learning the axle load is started in block F14. In block F15, the displacement sensor signal or the rotation angle sensor signal is read. Thus, in block F16, the actual level is determined. The axle load on the mechanically suspended axle 4 is determined in block F17 by means of a horizontal axle load characteristic curve stored in the memory of the control unit 10, wherein the measured actual level is associated with the axle load, or by means of an angle axle load characteristic curve, wherein the measured angle of rotation of the angle of rotation sensor is associated with the axle load, and is transmitted on the CAN bus 12 in block F18.

In turn, information about the axle load of the mechanically suspended axle 4 can be indicated on a display to the driver and/or used by other electronic control systems.

This provides axle load information about all axles 2, 4. If the control valve signal and the displacement sensor signal are not detected, the routine ends in block F19. If the pressure sensor signal is recorded, an error occurs even if the control valve signal is not present, and in block F20, the routine ends.

The routine of the method may be performed on any number of axles for mechanically, pneumatically/hydraulically or hybrid suspended vehicles.

List of reference numerals (integral part of the description)

1 level adjustment system

2 pneumatic/hydraulic suspension axle

3a first air suspension element

3b second air suspension element

4 mechanically suspended axle

5a first steel suspension element

5b second Steel suspension element

6 first displacement measuring device

6a displacement sensor of a first displacement measuring device

7 pressure measuring device

Pressure sensor of 7a pressure measuring device

8-valve circuit

First control valve of 8a valve circuit

Second control valve of 8b valve circuit

9 second displacement measuring device

9a displacement sensor of a second displacement measuring device

10 electronic control unit

11 operating unit of control unit

12 CAN bus

Function blocks of control methods F1-F20