ELECTRONIC CONTROL UNIT FOR A LEVEL CONTROL DEVICE OF A VEHICLE, AND METHOD FOR ASCERTAINING THE AXLE LOAD USING SUCH A CONTROL UNIT

Abstract

A control unit for a level control device of a mechanically and/or pneumatically/hydraulically suspended vehicle includes a control device configured to control the level and a sensor device 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 load on mechanically suspended axles and on pneumatically/hydraulically suspended axles. An interface is configured to receive signals from sensors suitable at least for ascertaining the load on mechanically suspended axles. The control unit has a first storage for sensor-specific characteristic curves and a second storage for an algorithm for processing or reprocessing the signals forwarded or processed using the interface. For each stored sensor type, the current load on the mechanically suspended axle in question can be ascertained by correlating the signal with the characteristic curve for the sensor type.

Claims

1. An electronic control unit of an electronically controlled level control apparatus of a vehicle, the vehicle being at least one of a mechanically and pneumatically/hydraulically suspended vehicle, the electronically controlled level control apparatus including a control device and a sensor device that are provided for level control and that are at least one of installed and functionally extended in the vehicle such that, in addition to the level control or instead of the level control, functions for determining an axle load on mechanically suspended vehicle axles and for determining the axle load on pneumatically/hydraulically suspended vehicle axles are available, the control unit comprising: an electrical interface configured to receive electrical measurement signals from sensors of different sensor types that are suitable at least for determining the axle load on the mechanically suspended vehicle axles; a first non-volatile memory for storing sensor-specific characteristic curves; a second non-volatile memory for storing an algorithm for processing or further processing sensor-specific measurement signals forwarded or processed by way of the electrical interface; wherein a current axle load on a relevant mechanically suspended vehicle axle is determinable for each stored type of sensor via a correlation of the respective sensor-specific measurement signal forwarded or processed by way of said electrical interface with the sensor-specific characteristic curve stored for the respective type of sensor.

2. The control unit of claim 1, wherein said electrical interface is a pulse width modulation interface.

3. The control unit of claim 1, wherein, via said electrical interface, measurement signals from the sensor arranged on the mechanically suspended vehicle axle or assigned to the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is based on a measurement principle that requires contact of the sensor with the vehicle axle and a vehicle body of the vehicle.

4. The control unit of claim 1, wherein, via said electrical interface, the measurement signals from the sensor arranged on the mechanically suspended vehicle axle or assigned to the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is based on a measurement principle that operates contactlessly between the vehicle axle and a vehicle body of the vehicle.

5. The control unit of claim 3, wherein, via said electrical interface, the measurement signals from the sensor arranged on or in the region of the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is a load sensor.

6. The control unit of claim 4, wherein, via said electrical interface, the measurement signals from the sensor arranged on or in the region of the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is a load sensor.

7. The control unit of claim 3, wherein, via said electrical interface, the measurement signals from the sensor arranged on or in the region of the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is a a travel sensor.

8. The control unit of claim 4, wherein, via said electrical interface, the measurement signals from the sensor arranged on or in the region of the mechanically suspended vehicle axle are capturable for determining the axle load; and, the sensor is a travel sensor.

9. A method for determining an axle load on a vehicle, the vehicle being mechanically and/or pneumatically/hydraulically suspended, wherein the axle load is determined via an electronic control unit of an electronically controlled level control apparatus of the vehicle, wherein a control device and a sensor device provided for level control are at least one of installed and functionally extended in the vehicle such that, in addition to the level control or instead of the level control, functions for determining the axle load on mechanically suspended vehicle axles and for determining the axle load on pneumatically/hydraulically suspended vehicle axles are available, the method comprising: capturing a measurement signal from a sensor and evaluating the measurement via an algorithm stored in the control unit in order to determine the axle load on a mechanically suspended vehicle axle, by way of an electrical interface of the control unit that is configured to receive electrical measurement signals from sensors of different sensor types that are suitable at least for determining the axle load on mechanically suspended vehicle axles; preselecting or determining the type of sensor provided for determining the axle load on the mechanically suspended vehicle axle; selecting a characteristic curve stored in a memory of the control unit for the preselected or determined type of sensor; assigning the axle load to the respective measured value of the captured measurement signal via the characteristic curve; and, outputting a corresponding signal that is dependent on the axle load.

10. The method of claim 9 further comprising, in a case of a vehicle with mixed mechanical and pneumatic/hydraulic suspension, carrying out a plausibility check implemented in the electronic control unit on a basis of which the level control apparatus identifies a respective suspension type of the vehicle axle, and the corresponding function for determining the axle load is then activated.

11. A level control apparatus of a vehicle for level control, the level control apparatus comprising: an electronic control unit; the electronically controlled level control apparatus including a control device and a sensor device that are provided for the level control and that are at least one of installed and functionally extended in the vehicle such that, in addition to the level control or instead of the level control, functions for determining the axle load on mechanically suspended vehicle axles and for determining the axle load on pneumatically/hydraulically suspended vehicle axles are available; said electronic control unit including an electrical interface configured to receive electrical measurement signals from sensors of different sensor types that are suitable at least for determining the axle load on mechanically suspended vehicle axles; said electronic control unit further including 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 sensor-specific measurement signals forwarded or processed by way of the electrical interface; wherein a current axle load on a relevant mechanically suspended vehicle axle is determinable for each stored type of sensor via a correlation of the respective sensor-specific measurement signal forwarded or processed by way of said electrical interface with the characteristic curve stored for a respective type of sensor; said electronic control unit being configured to: capture the measurement signal from such a sensor and evaluating the measurement signal via an algorithm stored in the control unit in order to determine the axle load on a mechanically suspended vehicle axle, by way of an electrical interface of the control unit that is configured to receive the electrical measurement signals from the sensors of the different sensor types that are suitable at least for determining the axle load on mechanically suspended vehicle axles; preselect or determine the type of sensor provided for determining the axle load on the mechanically suspended vehicle axle; select the characteristic curve stored in said first non-volatile memory of the control unit for the preselected or determined type of sensor; assign the axle load to a respective measured value of the captured measurement signal via the characteristic curve; and, output a corresponding signal that is dependent on the axle load.

12. A vehicle comprising the level control apparatus of claim 11.

13. The vehicle of claim 12, wherein the vehicle is a commercial vehicle or a passenger car.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] The invention will now be described with reference to the drawings wherein: FIG. 1 shows a level control apparatus, which is shown in a highly schematically simplified manner, and which is configured for determining the axle load, and for level control, on a vehicle equipped with mechanically and pneumatic suspended axles; and, FIG. 2 shows a flowchart of an embodiment of a method according to the disclosure for determining an axle load on a vehicle with mixed suspension according to FIG. 1.

DETAILED DESCRIPTION

[0037] The level control apparatus 1, which is shown in a simplified manner in FIG. 1, of a vehicle, for example an ECAS system, for example of a truck, has two adjustable air spring elements 3a, 3b, which are in the form of supporting bellows, for a resilient support of a vehicle body, which is not shown, with respect to a rear vehicle axle 2 in the form of a drive axle. In contrast, a front vehicle axle 4 is supported, that is, mechanically suspended, with respect to the vehicle body by way of two steel spring elements 5a, 5b in the form of helical compression springs.

[0038] A travel measuring apparatus 6 including a travel sensor 6a for capturing travel variables for level control, a pressure measuring apparatus 7 including at least one pressure sensor 7a for capturing pressure values for determining the axle load on the air-suspended vehicle axle 2, and a control valve apparatus 8, which is in the form of a valve circuit, including in each case one control valve 8a, 8b, which is in the form of a solenoid valve, for each air spring element 3a, 3b are assigned to the pneumatically/hydraulically suspended, in this case air-suspended, rear vehicle axle 2. The control valve apparatus 8 is switchably pneumatically connected to the air spring elements 3a, 3b and has a compressed-air connection, which is not designated in any more detail. An axle load measuring apparatus 9 including an axle load sensor 9a for determining the axle load on this axle 4 is assigned to the mechanically suspended, in this case steel-suspended, front vehicle axle 4.

[0039] Furthermore, an electronic control unit 10 is arranged between the vehicle body and the air-suspended vehicle axle 2 to evaluate the travel, axle load and pressure measured values and to control the air spring elements 3a, 3b to adjust a driving level. The electronic control unit 10 has an electrical interface 10a, which is configured to receive and transmit measurement signals from different types of sensor. The interface 10a is in particular able to capture and to further process measurement signals from different types of sensor, which may be arranged on the mechanically suspended vehicle axle 4 depending on the equipment of the vehicle. For this purpose, pulse width modulation of the received measurement signals may be carried out via the interface 10a, whereupon the modulated measurement values are supplied 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 different types of sensor are stored, for example in tables or value pairs.

[0040] Moreover, an operating unit 11 for a respective user is electrically connected to the control unit 10. The user is able to trigger or perform adjustments and a calibration of the level control apparatus 1 via the operating unit 11, for example as described in EP 2 097 278 B1. The control valve apparatus 8, the travel measuring apparatus 6 and the pressure measuring apparatus 7 assigned to the air-suspended axle 2, and the axle load measuring apparatus 9 assigned to the mechanically suspended axle are connected to the control unit 10 for signal transfer purposes. The control unit 10 has a CAN controller, by way of which the control unit 10 is connected to a CAN bus 12. The CAN controller controls interrupt requests and regulates the data transfer. The construction of a CAN bus in a vehicle and the connection of various bus subscribers to the CAN bus are known.

[0041] The travel sensor 6a for level control is fastened to the vehicle body in the vicinity of its assigned air-suspended vehicle axle 2 and is connected to the vehicle axle 2 by way of a lever system, which is not shown. The travel sensor 6a has a rotational angle sensor, which is not shown, and which captures the respective angular position of the lever system mentioned. The rotational movement of the lever system may be converted to a linear movement inside the travel sensor 6a, for example in the form of the plunging of an armature into a coil, wherein, during the plunging movement of the ferromagnetic armature into the stationary coil, a travel-dependent phase shift between the current and the voltage occurs, which is made available as an output signal that the control unit 10 receives. An actual level of the distance between the vehicle axle 2, 4 and the vehicle body is able to be determined from this signal. The value of the actual level may be used for level control on the air-suspended vehicle axle 2.

[0042] Level control of an air suspension using such a system is known per se. The travel sensor 6a for level control captures the distance between the vehicle axle and the vehicle body at specific time 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 target value stipulated in the control unit 10. In the case of an impermissible difference between the actual value and the target value, an actuating signal is transmitted from the control unit 10 to the control valve 8a, 8b. Depending on this actuating signal, the control valve 8a, 8b now actuates the air spring element 3a, 3b, which is in the form of a bellows, and supplies the air spring element with air or relieves the air spring element of air. As a result of the change in pressure in the air spring element 3a, 3b, the distance between the vehicle axle and the vehicle body also changes. The distance is captured again by the travel sensor 6a and the cycle starts over.

[0043] The axle load sensor 9a for determining the axle load on the mechanically suspended vehicle axle 4 is fastened to the vehicle body in the vicinity of its assigned vehicle axle 4. By way of example, the axle load sensor 9a may be in the form of a travel sensor, which is configured substantially structurally identically to the travel sensor 6a for level control. In the case of such an axle load sensor 9a, the value of the actual level is used to determine the axle load on the mechanically suspended vehicle axle 4. The determination of the axle load on the mechanically suspended vehicle axle 4 takes advantage of the simple relationship that the force that bears on the vehicle axle 4 is determined from the spring constant of the spring element 5a, 5b and the measured spring deflection, as a result of which the axle load of the vehicle is able to be determined via a level signal characteristic curve. This embodiment of an axle load sensor 9a should be considered purely by way of example. Alternatively, axle load sensors 9a that directly produce a load-dependent signal instead of a travel-dependent signal are taken into consideration. Such axle load sensors 9a are already known and constantly undergo further development.

[0044] According to the disclosure, the interface 10a of the control unit 10 is in any case configured in such a way that, as a common interface, it is able to process both signals from travel sensors and signals from load sensors that are produced on mechanically suspended vehicle axles. Only one algorithm is required, which, with the aid of a stored sensor-specific characteristic curve, converts the measurement signal from the sensor identified by the control unit 10 to an axle load value.

[0045] Furthermore, the control unit 10 may additionally receive signals from the pressure measuring apparatus 7 by way of the interface 10a in order to determine the axle load on the air-suspended vehicle axle 2. The determination of the axle load takes advantage of the relationship that the force that bears on the vehicle axle 4 is able to be inferred from a pressure value in the air spring element 3a, 3b, as a result of which an axle load value of the vehicle is able to be determined via a pressure signal characteristic curve.

[0046] Level control of an air suspension using such a system is not relevant per se to the disclosure and need not be described in detail here. The following embodiment is therefore restricted to the sequence of a method according to the disclosure for determining an axle load on the mechanically suspended vehicle axle 4, on the one hand, and on the air-suspended vehicle axle 2, on the other hand. FIG. 2 is used 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-suspended vehicle axle 2 and on the mechanically suspended vehicle axle 4.

[0047] The method starts with the activation of the level control apparatus 1, for example when an ignition system of the vehicle is switched on, according to a first function block F1. An axle-specific plausibility check is first of all carried out with three component queries, on the basis of which the program is divided into two program branches. These are a first routine, which determines the axle load on the air-suspended vehicle axle 2, and a second routine, which determines the axle load on the mechanically suspended 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-suspended vehicle axle are already described per se in DE 10 2017 011 753.5, corresponding to US 2020/0406800, mentioned at the outset, by the applicant. In contrast to this, an adapted plausibility check and a new second routine, which determines the axle load on the mechanically suspended vehicle axle 4, are presented here according to the disclosure.

[0048] Accordingly, the plausibility check starts with a first query F2 as to whether a signal of a control valve 8a, 8b that is not equal to zero is present in a predetermined period of time. There follows a second query F3 as to whether a signal of a travel sensor 6a that is not equal to zero is present in a predetermined period of time. There is then a third query F4 as to whether a signal of a pressure sensor 7a that is not equal to zero is present in a predetermined period of time. These queries are carried out in the same way on each vehicle axle 2, 4 or the associated components thereof.

[0049] If a control valve signal, a travel sensor signal and a pressure sensor signal are present, the air-suspended vehicle axle 2 is identified in block F5 and the associated routine for determining the axle load starts in block F6. In block F7, the pressure sensor signal is read out. In block F8, the axle load on the air-suspended vehicle axle 2 is determined via a pressure signal characteristic curve stored in a memory 10b of the control unit 10 and, in block F9, is transmitted on the CAN bus 12.

[0050] The axle load information of the air-suspended vehicle axle 2 may be displayed to the driver via a display and/or used by other electronic control systems. If no travel sensor signal is identified, although a control valve signal is present, no level control is possible on the air-suspended vehicle axle 2 according to block F10.

[0051] If no pressure sensor signal is registered, although a control valve signal and a travel sensor signal are present, no axle load measurement may take place 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.

[0052] If no control valve signal is present in block F2, but a travel sensor signal is present in block F3 and, however, no pressure sensor signal is present in block F4, the mechanically suspended vehicle axle 2 is identified in block F13 and the associated routine for determining the axle load starts in block F14. In block F15, the travel sensor signal or the rotational angle sensor signal is read out. In block F16, the actual level is determined therefrom. In block F17, the axle load on the mechanically suspended vehicle axle 4 is determined via a level signal characteristic curve, which is stored in the memory 10b of the control unit 10 and in which the measured actual level is correlated with the axle load, or via an angle signal characteristic curve, in which the measured rotational angle of the rotational angle sensor is correlated with the axle load, and, in block F18, is transmitted on the CAN bus 12.

[0053] If no control valve signal is present in block F2 and no travel sensor signal is present in block F3, according to the disclosure, a further query is carried out in block F21 as to whether a signal of a load sensor is present in a predetermined period of time. If this is the case, the mechanically suspended vehicle axle 2 is identified in block F13 and the associated routine for determining the axle load starts in block F14. In block F15a, the load sensor signal is read out. In block F17a, the axle load on the mechanically suspended vehicle axle 4 is determined via a load signal characteristic curve, which is stored in the memory 10b of the control unit 10 and in which the measured load signal is correlated with the axle load, and, in block F18, is transmitted on the CAN bus 12.

[0054] The axle load information relating to the mechanically suspended vehicle axle 4 may be displayed to the driver again by way of a display and/or used by other electronic control systems. The axle load information is therefore available at all of the vehicle axles 2, 4.

[0055] If neither a control valve signal, nor a travel sensor signal, nor a load sensor signal are identified, the routine ends in block F19. If, when a travel sensor signal is present, a pressure sensor signal is also registered, although no control valve signal is present, there is an error and the routine ends in block F20.

[0056] The routines of the method may be carried out on any number of vehicle axles for mechanically, pneumatically/hydraulically suspended vehicles or vehicles with mixed suspension.

[0057] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

LIST OF REFERENCE SIGNS (PART OF THE DESCRIPTION)

[0058] 1 Level control apparatus [0059] 2 Pneumatically/hydraulically suspended vehicle axle [0060] 3a First air spring element [0061] 3b Second air spring element [0062] 4 Mechanically suspended vehicle axle [0063] 5a First steel spring element [0064] 5b Second steel spring element [0065] 6 Travel measuring apparatus [0066] 6a Sensor, travel sensor of the travel measuring apparatus [0067] 7 Pressure measuring apparatus [0068] 7a Sensor, pressure sensor of the pressure measuring apparatus [0069] 8 Control valve apparatus, valve circuit [0070] 8a First control valve of the valve circuit [0071] 8b Second control valve of the valve circuit [0072] 9 Axle load measuring apparatus [0073] 9a Sensor, axle load sensor of the axle load measuring apparatus [0074] 10 Electronic control unit [0075] 10a Electrical interface of the control unit [0076] 10b First non-volatile memory of the control unit [0077] 10c Second non-volatile memory of the control unit [0078] 11 Operating unit of the control unit [0079] 12 CAN bus [0080] F1-F21 Function blocks of a control method