Safety mechanisms, motor controllers, and steering systems

Abstract

The invention relates to a safety mechanism for limiting a motor torque (MT) provided by an electric motor (5) mechanically coupled to a steering input (2) of a steering system (1) for applying the motor torque (MT) on the steering input (2) which is mechanically operable by an operator (90), wherein a torque indication value indicates the motor torque (MT). In order to increase the safety of the operation of the electric motor (5) the safety mechanism at least limits the motor torque (MT) if the torque indication value is outside a permission map (PM) of permissible torque indication values. The invention also relates to a motor controller (6) and a steering system (1).

Description

Technical Field

[0001] This invention relates to a safety mechanism for limiting the torque provided by an electric motor mechanically coupled to a steering input device of a steering system for applying the motor torque to the steering input device, which is mechanically operable by an operator. The invention also relates to a motor controller for such an electric motor and a steering system for a vehicle. Background Technology

[0002] Various types of hydraulic steering systems for vehicles are known. Steering commands ultimately cause a change in the wheel orientation angle of one or more steerable wheels of the vehicle relative to the vehicle's longitudinal axis, thereby changing the direction of the vehicle's movement.

[0003] Some hydraulic steering systems employ electro-hydraulic valves (e.g., fail-safe electro-hydraulic steering systems with emergency braking, hybrid steering systems employing conventional hydraulic steering units with at least one metering pump and electro-hydraulic valve assemblies, and steer-by-wire systems employing redundant electro-hydraulic valves).

[0004] For example, in DE102007053024A1 Figure 1 An exemplary hydraulic steering system is shown. Some modifications are described in EP2762387A1. The hydraulic steering system includes a (conventional) hydraulic steering unit and additionally includes an electro-hydraulic valve assembly that allows electronically controlled hydraulic steering (electro-hydraulic steering). The steering cylinder can be actuated by the electronic valve assembly and the hydraulic steering unit.

[0005] Typically, a steering wheel is used as the steering input device. The operator can mechanically operate the steering wheel to change the direction of the vehicle's movement.

[0006] Without additional measures, conventional hydraulic steering systems do not provide restoring force to the steering wheel, the restoring torque used to return the steering wheel to a neutral position corresponding to a neutral wheel orientation angle (which can be defined as zero). No tactile feedback is provided to the operator.

[0007] To provide tactile feedback to the operator, an electric motor can be mechanically coupled to the steering shaft of the steering column, which is rotatably connected to the steering wheel. The electric motor can apply motor torque to the steering shaft, and thus to the steering wheel. In particular, a restoring force can be generated to return the steering wheel to the neutral position, similar to the steering of a rack and pinion.

[0008] High safety requirements are placed on steering systems. It must be ensured that the operator has sufficient control of the vehicle at all times. For example, there are strong safety requirements regarding the sensors that provide data used to calculate the motor torque to be applied to the steering input. Such sensors could include, for example, wheel direction angle sensors for measuring the wheel direction angle of the steerable wheels. Redundant sensors can be provided, for example. Summary of the Invention

[0009] The problem behind this invention is to provide a method for improving the operational safety of an electric motor used in a steering system and mechanically coupled relative to a steering input device (e.g., a steering wheel) to provide motor torque at that steering input device.

[0010] This problem is solved by a security mechanism having the features of the present invention.

[0011] A safety mechanism is used to limit the motor torque provided by an electric motor that is mechanically coupled to the steering input device of the steering system for applying motor torque to the steering input device, for example, to provide tactile feedback to the user, wherein the steering input device can be mechanically operated by the user. A torque indication value indicates the motor torque.

[0012] If the torque indication value is outside the permission map of permissible torque indication values, the safety mechanism at least limits the motor torque. In this context, "torque indication value" can be the current torque indication value among a plurality of torque indication values.

[0013] Because of the permittivity chart, the permissible torque applied by the electric motor can be specifically adapted / customized for different situations. The permittivity chart can include multiple different thresholds for the permissible torque indication value (and the corresponding motor torque) for different situations.

[0014] Safety mechanisms ensure that the motor torque never exceeds the torque that the operator can handle. For example, a permissive chart may only permit torque indication values ​​corresponding to motor torques below a predetermined global maximum motor torque. The global maximum motor torque can be in the range of 3 Nm to 10 Nm, for example, in the range of 4 Nm to 6 Nm.

[0015] The term "torque indication value" can refer to any parameter that indicates the (to be applied) motor torque by an electric motor. Specifically, torque indication values ​​can include:

[0016] - Motor torque applied by an electric motor (e.g., the actual motor torque applied and / or the motor torque sensed by a torque sensor).

[0017] - The motor torque to be applied by the electric motor (e.g., the motor torque calculated by the controller).

[0018] - (e.g., by a motor controller) the current supplied to the electric motor, the current indicating the motor torque; and / or

[0019] - Control output data that indicates motor torque and / or current supplied to the electric motor, the current indicating motor torque.

[0020] Safety mechanisms can be additional, independent, and / or separate safety functions. For example, a safety mechanism can be implemented as a separate function from the torque calculation function used to calculate the torque indication value.

[0021] If the torque indication becomes excessive, the safety mechanism will intervene. This may occur, for example, in the following situations:

[0022] - There is an error in the calculation command used to calculate the torque indication value;

[0023] - Calculation instructions may exhibit unexpected behavior in certain situations;

[0024] – Properly handle errors in calculation instructions;

[0025] - and / or similar situations.

[0026] These types of errors cannot be prevented by requiring only the input data used to calculate the torque indication value, such as by redundancy requirements for steering input sensors, wheel direction angle sensors, etc.

[0027] Therefore, the present invention introduces additional protection against errors that may occur in determining the desired motor torque (or more generally, the torque indication value), for example in a motor controller for controlling an electric motor, and / or in transmitting the torque indication value to the electric motor.

[0028] According to one perspective, the safety agency itself does not participate in controlling the electric motor during normal operation.

[0029] Normal operation can mean that the torque indication value is within the expected boundaries (e.g., within the expected torque graph described below). Additionally or alternatively, normal operation can mean the absence of errors / malfunctions. Additionally or alternatively, normal operation can mean that the motor control works as expected without any undesirable behavior.

[0030] For example, the safety mechanism itself does not calculate the torque indication value. The safety mechanism does not know any of the motor torque, current, and control output data to be applied to the electric motor.

[0031] "Active steering" can mean (including the following): when the user actively operates the steering input device mechanically to increase the wheel direction angle of the steerable wheels away from the neutral wheel direction angle.

[0032] "Reaction steering" can mean (including the following): when the operator is not operating the steering input device. Reaction steering can also include: when the operator grips the steering input device without increasing the wheel direction angle of the steerable wheels away from the neutral position, and / or when the operator slows down the recovery movement of the steering input device toward the neutral position. This recovery movement can be caused by an electric motor applying motor torque (specifically, "recovery torque"). The neutral position (of the steering input device) can correspond to a neutral wheel direction angle, for example, corresponding to straight movement of the vehicle.

[0033] Based on the specific input data, the permissible diagram can enclose the permissible values ​​used for torque indication. The safety mechanism may include interfaces (e.g., hardware and / or software interfaces) for receiving the specific input data.

[0034] Specific input data may include (and in particular constitute) information about the speed of movement of the steering input device and / or the direction of movement of the steering input device (e.g., movement to the left or right).

[0035] The safety mechanism can be configured to receive torque indication values ​​(e.g., from a torque calculation function). The safety mechanism may include an interface (e.g., a hardware interface and / or a software interface) for receiving torque indication values. The safety mechanism can use the current torque indication value as input.

[0036] The safety mechanism can be configured to check whether the current torque indication value is within the permissible range. The safety mechanism may take into account the absolute value of the torque indication value, the "direction" of the torque indication value (e.g., positive or negative, and / or direction markings), and / or the specific input data currently available (e.g., information about the speed of movement of the steering input device).

[0037] In one embodiment, the permissive diagram corresponds to a region in the plane spanned by the axis representing the travel speed of the steering input device and the axis representing the torque indication value. The permissive diagram can define the permissible range for the torque indication value based on the travel speed of the steering input device. The permissible range can be different for at least two different travel speeds of the steering input device.

[0038] As an example only, in the plane, the x-axis (horizontal axis) may correspond to the speed of movement of the steering input device, and / or the y-axis (vertical axis) may correspond to the torque indication value, or vice versa.

[0039] As described above, the permission map can correspond to a region in the plane.

[0040] This region can be point-symmetric about the origin of the coordinate system. This corresponds to the behavior of the steering system, which is symmetrical to the operator's "feel" for left and right directions relative to the neutral position.

[0041] In one embodiment, the region is non-mirror-symmetric with respect to the axis associated with the torque indication value. Additionally or alternatively, the region may be non-mirror-symmetric with respect to the axis associated with the speed of movement of the steering input device. For the same direction of movement of the steering input device, this corresponds to different absolute values ​​of the permissible torque for active steering and for reaction steering.

[0042] According to one aspect, information regarding the movement of the steering input device may include the direction of movement of the steering input device. For example, a positive value may correspond to movement to the right (e.g., clockwise rotation of the steering wheel), and a negative value may correspond to movement to the left (e.g., counterclockwise rotation of the steering wheel). Additionally or alternatively, a flag may carry information regarding the direction of movement of the steering input device.

[0043] The torque indication value can include information corresponding to the absolute value of the motor torque and information corresponding to the direction of the motor torque. For example, a negative motor torque value can correspond to the motor torque that forces the steering input device to steer to the left, and a positive motor torque value can correspond to the motor torque that forces the steering input device to steer to the right.

[0044] Torque indication values ​​that are not surrounded (covered) by the permission map are outside the permission map and may be disallowed.

[0045] For example, the steering input device can be a steering wheel. The speed of movement of the steering input device can be expressed as the number of revolutions of the steering wheel per unit time, such as revolutions per minute.

[0046] The safety mechanism can be configured to determine whether active steering should occur at this time based on the current torque indication value and the current specific input data.

[0047] The safety mechanism can be configured to determine whether to engage counter-steering at this time based on the current torque indication value and the current specific input data.

[0048] Depending on one aspect, the permissible torque diagram presents different maximum permissible torque values ​​based on one, more, or all of the following:

[0049] - The speed at which the steering input device moves;

[0050] - The direction of movement of the steering input device; and

[0051] - Whether active steering occurs at this time.

[0052] In one embodiment, if the torque indication value is outside the permissible map, the safety mechanism shuts down the electric motor. Again, in this context, the "torque indication value" can be the current torque indication value among a plurality of torque indication values. As a result, the application of motor torque by the electric motor ceases. In other words, the application of active torque generated by the electric motor is limited to zero. This does not preclude the motor from still passively generating some inertia to resist movement of the steering input device caused by the operator.

[0053] Additionally or alternatively, the safety agency may generate fault indications, such as for switching the motor controller to a fault state, for switching the main controller of the steering system to a fault state, and / or for switching another controller of the vehicle to a fault state.

[0054] In reaction steering, the motor torque to be applied may include, and in particular, consist solely of, restoring torque. Restoring torque is used to return the steering input to the neutral position. Restoring torque can vary depending on vehicle speed and / or wheel direction angle. For example, restoring torque may become stronger with increasing vehicle speed. Additionally or alternatively, restoring torque may become stronger with increasing wheel direction angle.

[0055] The motor torque to be applied in active steering may include restoring torque. Additionally or alternatively, it may include damping torque. Damping torque provides additional resistance (damping) against an increase in the wheel direction angle of one or more steerable wheels away from the neutral position, i.e., resistance to further moving the steering input device away from its neutral position. The damping torque may increase as the speed of movement of the steering input device increases, as vehicle speed increases, and / or as the wheel direction angle becomes more pronounced.

[0056] In addition, the operator may have to overcome the inertia of the steering input device moving during active steering.

[0057] According to one aspect, the permissible diagrams for active steering and for reaction steering can be different. Compared to active steering, since the motor torque in reaction steering can consist solely of restoring torque, the limit for motor torque (and therefore the limit for the permissible torque indication value) can be set to a stronger value, at least for increased movement speeds of the steering input. In some cases of active steering (e.g., at higher vehicle speeds, significant wheel steering angles, and faster movement speeds of the steering input), relatively strong motor torque (and corresponding torque indication values) can be expected and tolerated, while in the case of reaction steering, the same motor torque would be unexpectedly high and caused by errors. In the case of weaker values ​​of reaction steering, at least for increased movement speeds of the steering input, the safety mechanisms are more sensitive to errors / failures and can, for example, shut down the electric motor earlier in the event of an error / failure.

[0058] In one embodiment, for reaction steering and for the same direction of movement of the steering input device, the permissible diagram includes permissible torque values ​​of varying intensities based on the speed of movement of the steering input device.

[0059] For example, for reaction steering and (at least) for the same direction of movement, as the absolute value of the speed of movement of the steering input device increases, the permissive diagram may include a first reduction in the absolute value of the permissible torque indication value, and may additionally include a second reduction.

[0060] In one embodiment, the permitting graph covers a desired torque graph having the motor torque expected to be applicable by the electric motor in normal operation, and additionally covers the tolerance immediately adjacent to the desired torque graph.

[0061] If the current torque indication value indicates a motor torque that is only slightly outside the expected torque map, the additional tolerance prevents unnecessary intervention by the safety mechanism. Torque indication values ​​within the tolerance “zone” can be practically acceptable, or at least do not indicate a serious error / failure. Because the permissible map includes tolerances, unnecessary restrictions on motor torque (e.g., by shutting down the electric motor) can be prevented. As mentioned above, the torque calculation function and the safety mechanism can be implemented separately. For example, the torque calculation function can be updated, and this may result in a slightly higher motor torque in some cases. The tolerance allows for such updates without requiring additional updates to the safety mechanism.

[0062] According to one aspect, the security mechanism is a software module of an electric motor controller for the electric motor. This allows for easy implementation. The software module can be configured to receive specific input data as input. The software module can be configured to access a license map located in memory (e.g., in the memory of the motor controller). The software module may include the license map and / or instructions for generating the license map. The invention also relates to a computer-readable medium storing code for implementing / executing a security mechanism having a license map.

[0063] In one embodiment, the security mechanism is configured to monitor at least one, more, or all of the following, for example, by monitoring corresponding data inputs(s):

[0064] - Motor torque;

[0065] – Current supplied to the electric motor; the current indicates the motor torque.

[0066] - Control output data indicating motor torque and / or the current supplied to the electric motor, where the current indicates the motor torque; and

[0067] – Specific input data, such as information about the speed of movement of the steering input device.

[0068] Specifically, the safety mechanism can be configured to (continuously) monitor the movement speed and torque indication values ​​of the steering input device (e.g., current), and limit the motor torque (e.g., by shutting down the electric motor) as long as the operating point defined by these parameters is outside the permissible diagram.

[0069] The above-mentioned problems are further solved by the motor controller according to the present invention.

[0070] The motor controller is used for an electric motor that is mechanically coupled to a steering input device of a steering system for applying motor torque to the steering input device (e.g., for providing tactile feedback to an operator), wherein the steering input device can be mechanically operated by an operator.

[0071] The motor controller includes a safety mechanism according to the invention.

[0072] The possible embodiments, modifications, and advantages described regarding the safety mechanism can be applied accordingly to the motor controller, and vice versa.

[0073] The motor controller may include a memory.

[0074] The license diagram and / or the instructions for generating the license diagram can be pre-stored in the memory.

[0075] The security mechanism may include, or be composed of, software modules. These software modules (e.g., corresponding code) may be pre-stored in memory.

[0076] The motor controller can be configured to receive torque indication values, for example, from the main controller of the steering system. It is possible that the motor controller itself includes torque calculation functionality, for example, as a separate software module. The corresponding code can be pre-stored in memory.

[0077] A motor controller can be configured to output current for operating an electric motor. The motor torque applied by the electric motor depends on the current. Therefore, the current indicates / is equivalent to the motor torque. Furthermore, internal control output data, for example, sent from a processor in the motor controller to a current output generator within the motor controller, can indicate / is equivalent to the motor torque.

[0078] The motor controller can be configured to operate an electric motor, which is an electronically commutated motor having at least three winding phases.

[0079] The above-mentioned problems are further solved by a steering system having the features of the present invention.

[0080] This steering system is a steering system for a vehicle, wherein the steering system includes a steering input device and an electric motor, the electric motor being mechanically connected to the steering input device for applying motor torque to the steering input device, the steering input device being mechanically operable by an operator.

[0081] The steering system includes at least the safety mechanism according to the invention. The steering system may include a motor controller according to the invention (wherein the motor controller includes the safety mechanism).

[0082] The embodiments, modifications, and advantages described with respect to any of the safety mechanisms and motor controllers can be applied accordingly to the steering system, and vice versa.

[0083] The steering input device may be a steering wheel. The steering system may include a steering column with a steering shaft that is mechanically connected to the steering input device. An electric motor may be mechanically connected to the steering input device via the steering shaft. The rotor of the electric motor may form part of the steering shaft.

[0084] The steering system can be a hydraulic steering system.

[0085] A hydraulic steering system may include a hydraulic steering cylinder and a hydraulic flow assembly for actuating the hydraulic steering cylinder, wherein the hydraulic flow assembly is operable using a steering input device. The steering input device may be functionally coupled to the hydraulic flow assembly mechanically and / or electronically for transmitting operator steering commands from the steering input device to the hydraulic flow assembly.

[0086] The hydraulic flow assembly may include a metering pump and / or an electro-hydraulic valve assembly. The metering pump may be mechanically coupled to the steering input device, for example, via a steering shaft and / or an electric motor.

[0087] The hydraulic flow assembly can be hydraulically coupled to the steering cylinder. The steering cylinder can be mechanically coupled to at least one steerable wheel.

[0088] The steering system may include a steering input sensor for measuring the position and / or the speed of movement of the steering input device. The speed of movement can be calculated based on the subsequent position. The steering system may be configured to (at least) change the damping torque applied to the steering input device using the electric motor based on the speed of movement of the steering input device.

[0089] According to one aspect, the steering system includes a wheel direction angle sensor for measuring the wheel direction angle of the steerable wheels, wherein the steering system is configured to (at least) change the restoring torque applied to the steering input device using the electric motor based on the wheel direction angle. This allows for better tactile feedback to the operator and therefore better control of the vehicle.

[0090] Additionally or alternatively, the steering system may include a vehicle speed sensor for measuring vehicle speed, and wherein the steering system is configured to (at least) change at least one of the damping force and restoring force applied to the steering input device using the electric motor based on the vehicle speed. This allows for better tactile feedback to the operator and thus better control of the vehicle. In particular, the restoring force and / or damping force may become stronger as vehicle speed increases. This reduces the risk of the operator unintentionally abruptly maneuvering the steering input device at high vehicle speeds.

[0091] In one embodiment, the electric motor is an electronically commutated electric motor with at least three winding phases. This type of electric motor allows for the precise application of the desired motor torque.

[0092] Vehicles can be, for example, agricultural vehicles (e.g., tractors, harvesters, or cherry pickers), construction site vehicles (e.g., bulldozers, excavators, backhoe excavators, or asphalt pavers), self-propelled work machines (e.g., sweeper vehicles), or industrial machinery, heavy machinery (e.g., trucks), utility machinery (e.g., forklifts, cranes, or telescopic forklifts), off-highway vehicles, all-terrain vehicles, marine vehicles, etc.

[0093] The present invention also relates to vehicles having such a steering system.

[0094] Additional features, advantages, and possible applications of the invention arise from the following description of exemplary embodiments and accompanying drawings. All features described and / or illustrated herein, individually or in any desired combination, form the subject matter of the invention, regardless of how they are combined in the claims or in their references to preceding claims. Attached Figure Description

[0095] Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0096] Figure 1 A vehicle having a steering system according to the invention is schematically shown, the steering system comprising an electric motor mechanically coupled to a steering wheel via a steering shaft and a motor controller for driving the electric motor.

[0097] Figure 2 schematically shown Figure 1 Modifications to the steering system, in which the main steering controller and motor controller are separated; and

[0098] Figures 3A to 3C It schematically shows the situation in relation to Figure 1 or Figure 2 The permissible torque indication value is defined in the plane spanned by the horizontal axis corresponding to the steering wheel movement speed of the steering system and the vertical axis corresponding to the torque indication value. Detailed Implementation

[0099] Figure 1 A vehicle 100 with two steerable wheels 101 is shown. The wheel orientation angle of the steerable wheels 101 relative to the longitudinal axis LA of the vehicle 100 can be changed via the steering system 1.

[0100] The steering system 1 includes a steering input device in the form of a steering wheel 2. An operator 90 can mechanically input steering commands to change the wheel direction angle using the steering wheel 2. Specifically, the operator 90 can turn the steering wheel 2 in two opposite directions of movement (i.e., left LW and right RW). From the operator 90's perspective, turning the steering wheel 2 to the left LW corresponds to a counter-clockwise rotation of the steering wheel 2. From the operator 90's perspective, turning the steering wheel 2 to the right RW corresponds to a clockwise rotation of the steering wheel 2.

[0101] The steering wheel 2 is mechanically rotatably connected to the steering shaft 3 of the steering column 4.

[0102] The electric motor 5 is mechanically connected to the steering shaft 3, and thus connected to the steering wheel 2 via the steering shaft 3. The electric motor 5 can apply motor torque MT to the steering shaft 3, and thus to the steering wheel 2.

[0103] Motor controller 6 drives electric motor 5. Motor controller 6 supplies current MC to electric motor 5. Current MC determines the motor torque MT generated by electric motor 5 and is indicated / equivalent to motor torque MT.

[0104] Note that the rotor of the electric motor 5 can form part of the steering shaft 3.

[0105] Alternatively, the motor controller 6 can be integrated into the housing of the electric motor 5.

[0106] In this example, steering system 1 is a hydraulic steering system. The hydraulic steering system includes a hydraulic flow assembly 7. The hydraulic flow assembly 7 allows for hydrostatic steering.

[0107] The hydraulic supply unit 8 supplies pressurized hydraulic fluid to the hydraulic flow assembly 7. The hydraulic supply unit 8 is connected to the hydraulic flow assembly 7 via a fluid supply line 9 and a fluid return line 10. The hydraulic supply unit 8 is part of the vehicle 100. Therefore, the hydraulic supply unit 8 can form part of the steering system 1.

[0108] The vehicle 100 has a steering cylinder 11, which is hydraulically connected to the hydraulic flow assembly 7 via fluid connectors 11a and 11b. The steering cylinder 11 and / or the fluid connectors 11a and 11b may form part of the steering system 1.

[0109] The steerable wheel 101 is operably connected to the hydraulic steering cylinder 11.

[0110] The hydraulic flow assembly 7 controls the supply of hydraulic fluid to the steering cylinder 9. It may include a conventional hydraulic steering unit with at least one metering pump 71. Additionally or alternatively, it may include at least one electro-hydraulic valve assembly 72. In this embodiment, both the metering pump 71 and the electro-hydraulic valve assembly 72 are shown together.

[0111] Regarding conventional hydraulic steering units, the following can be applied: The steering wheel 2 can be turned by the driver. By turning the steering wheel 2, two components of the conventional hydraulic steering unit (specifically, the valve core and sleeve) move relative to each other to open a certain number of orifices in the main flow path. This allows a certain amount of hydraulic fluid to pass through the main flow path. This hydraulic fluid drives a flow meter, which in turn restores the initial relative position of the two components. Therefore, when the steerable wheel 101 has reached the position commanded by the steering wheel 2, the main flow path is closed again. This conventional hydraulic steering unit is known as the OSP steering unit from Danfoss.

[0112] The metering pump 71 is mechanically connected to the steering wheel 2 via the steering shaft 3.

[0113] The steering input sensor 12 may be located at the steering column 4, in the electric motor 5, and / or in the steering input device (e.g., the steering wheel 2) itself.

[0114] Steering input sensor 12 provides steering input data SID. The steering input data SID includes information from which the speed and direction of movement (i.e., left or right) of the steering wheel 2 can be obtained. For example, steering input sensor 12 can directly measure the speed and direction of movement of the steering shaft 3, and therefore measure the speed and direction of movement of the steering wheel 2. Alternatively, steering input sensor 12 can measure the (rotational) position of the steering shaft 3, and therefore measure the (rotational) position of the steering wheel 2. In this case, the speed and direction of movement of the steering wheel 2 can be obtained based on subsequent measurements of the (rotational) position.

[0115] According to one aspect, at least two or all of the following can be constructed together in a single unit: electric motor 5, motor controller 6, steering column 4, steering input sensor 12, and hydraulic flow assembly 7.

[0116] Alternatively, a vehicle speed sensor 13 may be provided. The vehicle speed sensor 13 provides vehicle speed data (VSD) indicating the speed of the vehicle 100 (vehicle speed).

[0117] In addition, the vehicle 100 may include a wheel direction angle sensor 14. The wheel direction angle sensor 14 provides wheel direction angle data WDD indicating the wheel direction angle of at least one of the steered wheels 101.

[0118] In an exemplary embodiment, the motor controller 6 includes a processor 61, a memory 62 connected to the processor 61, and a current output unit 63 connected to the processor 61.

[0119] The current output unit 63 is configured to supply current MC to the electric motor 5 according to control output data COD. The control output data COD indicates the current MC to be applied, and therefore also the motor torque MT to be applied. The control output data COD can be provided by the processor 61, such as... Figure 1 As shown.

[0120] The motor controller 6 has an interface 64 for receiving steering input data SID. Interface 64 can be data-connected to the processor 61.

[0121] For example, the motor controller 6 can receive steering input data SID directly from the steering input sensor 12 as shown in the figure, from other controllers, and / or from the data bus.

[0122] Optionally, the motor controller 6 has an input 65 for receiving vehicle speed data VSD, for example, directly from the vehicle speed sensor 13, from other controllers, and / or from a data bus. The interface 65 can be data-connected to the processor 61.

[0123] Alternatively or additionally, the motor controller 6 may have an input 66 for receiving vehicle direction angle data WDD, for example, directly from the vehicle speed sensor 13, from other controllers, and / or from a data bus. Interface 65 may be data-connected to the processor 61.

[0124] According to another aspect, the motor controller 6 may have an output unit 67 for outputting control data for the hydraulic flow assembly 7. For example, the motor controller 6 may also be configured to operate the electro-hydraulic valve assembly 72 based at least on steering input data SID. The motor controller 6 may also take into account wheel direction angle data and / or vehicle speed data VSD for controlling the electro-hydraulic valve assembly 72.

[0125] The motor controller 6 can be configured to calculate the control output data COD itself based on one, more, or all of the steering input data SID, vehicle speed data VSD, and wheel direction angle data WDD.

[0126] Accordingly, the motor controller 6 itself includes a torque calculation function. This torque calculation function can be implemented as a software module. The memory 62 can store instructions (TCC) for performing the torque calculation function. The instructions (TCC) can include computer program code.

[0127] However, it is also possible that the motor controller 6 has an interface 68 for receiving control output data COD1 (see...). Figure 2 The control output data COD1 indicates the motor torque MT that should be applied by the electric motor 5.

[0128] like Figure 2 As illustrated in the exemplary modification, another controller (e.g., a separate main controller 80 of the steering system 1) generates control output data COD1, which indicates the motor torque MT to be applied by the electric motor 5. Therefore, in this case, the torque calculation function is implemented in the main controller 80. In other words, torque calculation functions and safety mechanisms are implemented in two different controllers 6, 80. Similarly, these functions can be implemented in two different controller sections of a single controller. Figure 2 In this process, processor 61 can generate control output data COD based on control output data COD1. Alternatively, processor 61 can simply pass control output data COD1 as control output data COD.

[0129] In addition, Figure 2 In this configuration, the main controller 80 controls the electro-hydraulic valve assembly 72 and is connected to the vehicle speed sensor 13 and the wheel direction angle sensor 14. Figure 2 In this configuration, both the motor controller 6 and the main controller 80 directly receive the steering input data SID. In principle, it is sufficient for one controller (6 or 80) to receive the steering input data SID and transmit the relevant information to the other controller (6 or 80).

[0130] exist Figure 1 In the middle, the motor controller 6 may include Figure 2 Some or all of the functions of the main controller 80.

[0131] exist Figure 1 and Figure 2 In the motor controller 6, the memory 62 stores the licensed diagram MP and / or the code used to generate the licensed diagram MP.

[0132] about Figures 3A to 3C The diagram MP and the safety mechanism for shutting down electric motor 5 are explained. All of them. Figures 3A to 3C They can be collectively referred to as Figure 3.

[0133] If the applied motor torque MT is outside the permitted area MP, the safety mechanism automatically shuts down the electric motor 5. If the motor torque MT is anywhere within the prohibited area FR, taking into account the current steering wheel speed TS, then the motor torque MT is outside the permitted area MP. In Figure 3, the boundary of the permitted area MP demarcates the permitted area MP from the prohibited area FR.

[0134] In other words, when the motor torque MT (or equivalent torque indication value) is in the prohibited region FR, the safety mechanism automatically shuts down the electric motor 5. This prevents the application of excessive motor torque, or even motor torque that cannot be handled by the operator 90.

[0135] Figures 3A to 3C An exemplary graphical representation of the permissive diagram MP is shown in the (virtual) plane spanned by the steering wheel 2's moving speed TS (x-axis) as the horizontal axis and the motor torque MT (y-axis) as the vertical axis. Here, the moving speed TS refers to the steering speed of the steering wheel 2. It should be noted that the current MC and control output data COD, COD1 indicate the motor torque MT to be applied by the electric motor 5. Therefore, although the reference numeral MT is used for the vertical axis in FIG3, the permissive diagram MP is alternatively or additionally defined for the control output data COD, control output data COD1, and / or motor current MC.

[0136] A positive value for the movement speed TS indicates that steering wheel 2 is turning right (RW). A negative value for the movement speed TS indicates that steering wheel 2 is turning left (LW). In other words, the sign of the movement speed TS indicates the direction of movement of steering wheel 2. The absolute value of the movement speed TS indicates the "fastness" of the movement speed. When the movement speed TS is zero, steering wheel 2 is not turning.

[0137] When the motor torque MT has a positive value, the electric motor 5 will apply a right-oriented motor torque MT. When the motor torque MT has a negative value, the electric motor MT will apply a left-oriented motor torque. In other words, the sign (positive or negative) of the motor torque MT indicates the orientation of the motor torque MT. The absolute value of the motor torque MT (the absolute value of the y-axis value) corresponds to the intensity of the motor torque MT to be applied. When the motor torque MT is zero, the motor torque MT will not be applied.

[0138] The first quadrant Q1 of the coordinate system in Figure 3 relates to the following situation: the steering wheel 2 is turned right (RW), and the electric motor 5 should apply a right-oriented motor torque MT. This applies to the reaction steering that returns the steering wheel 2 from the left side of the neutral position back to that neutral position. This corresponds to returning the wheel directional angle from a leftward tilt (for a left turn of vehicle 100) to a neutral wheel angle direction (for a straight forward movement of vehicle 100). Therefore, the pictogram in the upper right corner of Figure 3 shows the steering wheel 2 turning right (RW) while the operator 90's hand is pulled away from the steering wheel 2.

[0139] Similarly, the third quadrant Q3 of the coordinate system in Figure 3 relates to the leftward LW movement of the steering wheel 2 during reaction steering.

[0140] The second quadrant Q2 of the coordinate system in Figure 3 relates to the following situation: the steering wheel 2 is turned left (LW), and the electric motor 5 applies a right-oriented motor torque MT. This applies during active steering when the operator 90 actively operates the steering wheel 2 left (LW) to move the steerable wheel 101 left (LW) away from the neutral wheel angle direction. Therefore, the pictogram in the upper left corner of Figure 3 illustrates the steering wheel 2 turning left (LW) while the operator 90's hand engages the steering wheel 2.

[0141] Similarly, in the coordinate system of Figure 3, the fourth quadrant Q4 involves the operator's rightward RW active turn 90.

[0142] The symbol for ratchet 50, see specifically. Figure 3B The symbol illustrates the application of the motor torque MT of the electric motor 5 to the steering wheel 2.

[0143] During reaction steering (see first quadrant Q1 and third quadrant Q3), the motor torque MT is in the same direction as the moving speed TS. During reaction steering, the motor torque MT consists only of "restoring torque". Restoring torque is used to center the steering system 1 toward the neutral wheel direction angle and to provide corresponding feedback to the operator 90. As the deviation of the wheel direction angle from the neutral wheel direction angle increases, that is, as the absolute value of the wheel direction angle increases (since the neutral wheel direction angle can be limited to zero), the restoring torque can become stronger. Additionally or alternatively, the restoring torque can become stronger with increasing vehicle speed.

[0144] During active steering, the motor torque MT is oriented in the opposite direction to the movement speed TS. During active steering, the motor torque MT includes restoring torque and additional damping torque. The damping torque further increases the "resistance" (damping) against the increase in the absolute value of the wheel steering angle. The damping torque can become stronger as the steering wheel 2 moves faster at TS, as the vehicle speed increases, and / or as the absolute value of the wheel steering angle increases.

[0145] In addition, during active steering, the operator 90 may feel the inertia caused by the electric motor 5 (and / or other components rotatably connected to the steering wheel 2) as additional resistance to turning the steering wheel 2.

[0146] As can be clearly seen from the above, the actual motor torque MT depends on different conditions and can vary significantly. However, a "predicted torque map" ETM can be defined, where the motor torque MT can be expected to be in normal operation under any circumstances.

[0147] The expected torque graph (ETM) includes:

[0148] - (Steering wheel 2) Subgraph ERR used for rightward movement during counter-steering (i.e., in the first quadrant Q1, TS>0, MT>0).

[0149] - The subgraph ELA used for leftward movement during active steering (i.e., in the second quadrant Q2, TS<0, MT>0);

[0150] - and the subgraph ELR used for leftward movement during reaction steering (in the third quadrant Q3, TS<0, MT<0); and

[0151] - The subgraph ERA used for rightward movement during active steering (i.e., in the fourth quadrant Q4, TS>0, MT<0);

[0152] Since the motor torque MT includes the additional damping torque during active steering, it can be expected that the motor torque MT during active steering will reach a higher strength (larger absolute value) than during reaction steering. This means that, for active steering, the torque graph ETM is expected to cover a higher absolute value of the motor torque MT compared to reaction steering.

[0153] As in Figure 3B As can be seen in the example, subgraph ELA has the maximum active strength ELAM to the left. In this context, "to the left" refers to the direction of movement of steering wheel 2, i.e., the movement speed TS is negative, and the counter-torque CTL oriented to the right applies here. Figure 3B In the second quadrant Q2, the right-oriented counter-torque CTL during active left steering is schematically depicted and referenced. Similarly, in the fourth quadrant Q4, the left-oriented counter-torque CTR during active right steering is schematically depicted and referenced.

[0154] Subgraph ELA has a minimum strength of zero (meaning there is no negative / leftward oriented motor torque MT).

[0155] The subgraph ERA has a maximum rightward active strength ERAM and a minimum strength of zero (meaning there is no positive / rightward directional motor torque MT). Note that the maximum rightward active strength ERAM can correspond to -ELAM.

[0156] The subgraph ERR has a maximum rightward reaction strength ERRM and a minimum strength of zero (meaning there is no negative / leftward motor torque MT).

[0157] The subgraph ELR has a maximum left-hand reaction strength ELRM and a minimum strength of zero (meaning there is no positive / right-directed motor torque MT). Note that the maximum left-hand reaction strength ELRM can correspond to -ERRM.

[0158] It is likely expected that steering wheel 2 cannot return to the neutral position at an arbitrarily fast moving speed TS. Therefore, if the moving speed TS is faster than a certain recovery speed threshold RST, motor torque MT is not applied in counter-steering. Thus, the upper limit of subgraph ELR is -RST, and the upper limit of subgraph ERR is +RST (see [reference]). Figure 3B ).

[0159] exist Figure 3B In the first quadrant Q1, the right-oriented restoring torque RTR is schematically depicted and referenced, and in the third quadrant Q3, the left-oriented restoring torque RTL is schematically depicted and referenced.

[0160] The permissible torque indication value is defined by the permissible diagram MP. As long as the motor torque MT is within the permissible diagram, the safety mechanism will not intervene. Note again that the current MC and / or control output data COD, COD1 can be considered equivalent to the motor torque MT.

[0161] The permitting chart MP at least completely covers the expected torque chart ETM. As shown in Figure 3, the permitting chart MP can additionally cover the tolerance TO immediately adjacent to the expected torque chart. This prevents the safety mechanism from intervening in cases of irrelevant minor errors / failures.

[0162] The shape of the tolerance TO and / or the shape of the permission map MP can be adapted to the shape of the expected torque map ETM.

[0163] According to the depicted exemplary embodiment, in the second quadrant Q2, the permittivity map MP is uniformly defined by the threshold TA. In the second quadrant Q2, the tolerance TO has a uniform tolerance gap GDL for active leftward steering.

[0164] Similarly, in quadrant Q4, the permissive map MP is uniformly defined by the threshold TB. In quadrant Q2, the tolerance TO has a uniform tolerance clearance GDR for active right steering. Note that the thresholds TA and TB can have the same absolute value but different signs, i.e., TB = -TA (corresponding to the opposite direction of the motor torque MT). The tolerance clearances GDL and GDR can have the same width.

[0165] For reaction-driven turns, i.e. in the first quadrant Q1 and the third quadrant Q3, the boundaries of the permittivity map MP are not uniform, for example, they are stepped.

[0166] In this exemplary embodiment and as Figure 3A As shown, in the first quadrant Q1 (i.e., for right-hand reaction steering), for slow moving speeds TS up to a first speed threshold TS1R, the permissible map MP is defined by a threshold TA. For moving speeds TS faster than the first speed threshold TS1R, the permissible map MP is defined by a first decreasing threshold T1R. The first decreasing threshold T1R corresponds to a motor torque MT that is weaker than the threshold TA. In other words, the absolute value of the first decreasing threshold T1R is lower than the absolute value of the threshold TA, for example, at least 10% lower.

[0167] Therefore, for rightward reaction steering, as the rate of increase in the moving speed TS increases, the boundary of the permitting diagram MP has a first descending step S1R (to the right) (see...) Figure 3C The tolerance TO leaves a "velocity tolerance gap" SG1R between the zero-velocity side of subgraph ELA and the prohibited area FR located outside the permitted map MP in the first quadrant Q1.

[0168] The first reduction threshold T1R can be weaker than the maximum active strength to the left, ELAM (i.e., with a smaller absolute value). The velocity tolerance gap SG1R avoids unnecessary intervention by the safety mechanism.

[0169] In the first quadrant Q1, for a moving speed TS that is faster than the second speed threshold TS2R (which is faster than the first speed threshold TS1R), the permissible map MP can be defined by a second reduction threshold T2R. The second reduction threshold T2R corresponds to a motor torque MT that is weaker than the first reduction threshold T1R. In other words, the absolute value of the second reduction threshold T2R is lower than the absolute value of the first reduction threshold T1R, for example, at least 10% lower.

[0170] Therefore, with the rapid increase in the speed of movement used for rightward reaction steering, the boundary of the permitting diagram MP in the first quadrant Q1 can have a (rightward) second lowering step SG2R (see...). Figure 3CThe tolerance TO leaves a speed tolerance gap SG2R between the fast end of the expected torque graph ETM in the first quadrant Q1 (see the fast end of the subgraph ERR at moving speed + RST) and the prohibited area FR. Therefore, the second speed threshold T2R is faster than the moving speed threshold RST.

[0171] The second reduction threshold T2R can be weaker than the maximum rightward reaction strength ERRM.

[0172] The interpretation of the boundary of the licensed graph MP in the first quadrant Q1 can be correspondingly applied to the interpretation of the boundary of the licensed graph MP in the third quadrant Q3.

[0173] Similarly, the boundary of the permit map MP in the third quadrant Q3 can have a first decreasing step S1L (to the left) at the first velocity threshold TS1L (e.g., -TS1R) (see... Figure 3C The torque intensity decreases from a threshold TB (e.g., -TA) to a first decreasing threshold T1L (e.g., -T1R). A tolerance TO may include a velocity tolerance gap SG1L between the zero-velocity side of the subgraph ERA and the prohibited region FR located outside the permitted map MP in the third quadrant Q3. The first decreasing threshold T1L may be weaker than the maximum rightward active intensity ERAM (i.e., having a smaller absolute value). Furthermore, a second (leftward) decreasing step S2L may exist at the (leftward) second velocity threshold TS2L (e.g., -TS2R) (see...). Figure 3C This corresponds to a further reduction in the permitted motor torque to a second reduction threshold T2L (e.g., -T1L).

[0174] The Permitted Torque Map (MP) and / or Extended Torque Map (ETM) can be point-symmetric about the origin of the coordinate system in Figure 3. However, because the Permitted Torque Map (MP) has different shapes / characteristics for reaction steering and active steering, it is neither mirror-symmetric about the horizontal axis nor about the vertical axis. The same applies to the Expected Torque Map (ETM).

[0175] When the safety mechanism intervenes (e.g., shuts down the electric motor 5), it can also generate fault signals, such as for the vehicle controller, operator 90, main controller 80 and / or the like.

[0176] When the safety authority intervenes, it can switch the motor controller 6 to a fault state. The motor controller 6 can be configured to keep the electric motor 5 off as long as the fault state applies. Switching the motor controller 6 out of the fault state may require special confirmation, such as confirmation from the operator 90 or maintenance personnel.

[0177] The instruction set (SMC) used to execute the safety mechanism can be pre-stored in the memory 62 of the motor controller 6. The instruction may include corresponding computer program code. The licensed diagram (MP) (and / or the instructions used to generate the licensed diagram MP) can form part of the instruction set (SMC).

[0178] Even in Figure 1 In this case, the safety mechanism and torque calculation function are implemented separately. Two corresponding separate software modules are provided (see...). Figure 1 The separate instructions TCC and SMC in the code. Figure 2 In this context, the software module providing torque calculation functionality is even embedded in a controller different from the motor controller 6, which has a safety mechanism (i.e., the main controller 80, see [link]). Figure 2 In the TCC instruction.

[0179] Globally, the maximum motor torque MT permitted by the permitting graph MP is the motor torque MT corresponding to the absolute value of the thresholds TA and TB. Therefore, this absolute value can be referred to as the global maximum torque.

[0180] List of reference numerals

[0181] 1: Steering System

[0182] 2: Steering input device (steering wheel)

[0183] 3: Steering shaft

[0184] 4: Steering column

[0185] 5: Electric motor

[0186] 6: Motor controller

[0187] 7: Hydraulic Flow Component

[0188] 8: Hydraulic supply pipeline

[0189] 9: Fluid supply pipeline

[0190] 10: Fluid return line

[0191] 11: Steering cylinder

[0192] 11a, 11b: Fluid connectors

[0193] 12: Steering input sensor

[0194] 13: Vehicle speed sensor

[0195] 14: Wheel Direction Angle Sensor

[0196] 50: Symbol for ratchet

[0197] 61: Processor

[0198] 62: Memory

[0199] 63: Current output unit

[0200] 64, 65, 66: Interfaces

[0201] 67: Output Section

[0202] 68: Interface

[0203] 71: Metering pump

[0204] 72: Electro-hydraulic valve assembly

[0205] 80: Main Controller

[0206] 90: Operator

[0207] 100: Vehicles

[0208] 101: Steering wheels

[0209] COD, COD1: Control output data

[0210] CTL, CTR: Reverse Torque

[0211] ELA, ERA: Subgraphs

[0212] ELR, ERR: Subgraphs

[0213] ELAM, ERAM: Maximum active intensity

[0214] ETM: Expected Torque Graph

[0215] FR: Restricted Area

[0216] GDL, GDR: Tolerance Gap

[0217] LA: Longitudinal axis

[0218] LW: Left

[0219] MC: Current

[0220] MT: Motor Torque

[0221] PM: Permit Image

[0222] Q1: First Quadrant

[0223] Q2: Second Quadrant

[0224] Q3: Third Quadrant

[0225] Q4: Fourth Quadrant

[0226] RTL, RTR: Torque recovery

[0227] RW: Right

[0228] S1L, S1R: First lowering step

[0229] S2L, S2R: Second lowering step

[0230] SG1L, SG1R: Speed ​​tolerance clearance

[0231] SG2L, SG2R: Speed ​​tolerance gap

[0232] SID: Steering Input Data

[0233] SMC: Instructions

[0234] SMC: Instructions

[0235] TA, TB: Thresholds

[0236] T1L, T1R: First reduction threshold

[0237] T2L, T2R: Second reduction threshold

[0238] TS1L, TS2R: First speed threshold

[0239] TS2L, TS2R: Second speed threshold

[0240] TCC: Instructions

[0241] TO: Tolerance

[0242] TS: Movement Speed

[0243] RST: Recovery speed threshold

[0244] VSD: Vehicle Speed ​​Data

[0245] WDD: Wheel direction angle data.

Claims

1. A safety mechanism for limiting motor torque (MT) provided by an electric motor (5), the electric motor being mechanically coupled to a steering input device (2) of a steering system (1) for applying the motor torque (MT) to the steering input device (2), the steering input device (2) being mechanically operable by an operator (90), wherein a torque indication value indicates the motor torque (MT). If the torque indication value is outside the permissible torque indication value permissible map (PM), then the safety mechanism at least limits the motor torque (MT).

2. The safety mechanism according to claim 1, wherein if the motor torque (MT) is outside the permitted diagram (PM), the safety mechanism shuts down the electric motor (5).

3. The safety mechanism according to any one of the preceding claims, wherein the clearance diagram (PM) for active steering and the clearance diagram (PM) for reactive steering are different.

4. The safety mechanism according to any one of the preceding claims, wherein for reaction steering and for the same direction of movement (LW, RW) of the steering input device (2), the permissible diagram (PM) includes permissible torque values ​​(TA, TB, T1L, T1R, T2L, T2R) of different intensities based on the speed of movement (TS) of the steering input device (2).

5. The security agency according to any one of the preceding claims, wherein the license map (PM) covers: Expected Torque Map (ETM), which has a motor torque (MT) that can be expected to be applied by the electric motor (5) during normal operation, and Additionally, the tolerance (TO) immediately adjacent to the expected torque diagram (ETM).

6. The safety mechanism according to any one of the preceding claims, wherein the safety mechanism is a software module of the motor controller (6) for the electric motor (5).

7. The security mechanism according to any one of the preceding claims, wherein the security mechanism is configured to monitor at least one, more, or all of the following: - Motor torque (MT); - Current (MC) supplied to the electric motor (5), the current (MC) indicating the motor torque (MT); - Control output data (COD), which indicates the motor torque (MT) and / or the current (MC) supplied to the electric motor (5), which indicates the motor torque (MT); and - Information regarding the moving speed of the steering input device (2).

8. A motor controller (6) for an electric motor (5), said electric motor being mechanically coupled to a steering input device (2) of a steering system (1) for applying motor torque (MT) to said steering input device (2), said steering input device (2) being mechanically operable by an operator (90), The motor controller (6) includes a safety mechanism according to any one of the preceding claims.

9. The motor controller (6) according to claim 8, wherein the motor controller (6) includes a memory (62), wherein the license diagram (PM) and / or instructions for generating the license diagram (PM) are pre-stored in the memory (62).

10. A steering system (1) for a vehicle (100), wherein the steering system (1) includes a steering input device (2) and an electric motor (5), the electric motor being mechanically coupled to the steering input device (2) for applying motor torque (MT) to the steering input device (2), the steering input device (2) being mechanically operable by an operator (90). The steering system (1) mentioned above includes at least one of the following: - The security apparatus according to any one of claims 1 to 7; and - The motor controller (6) according to claim 8 or 9.

11. The steering system (1) according to claim 10, wherein the steering system (1) is a hydraulic steering system and includes a hydraulic steering cylinder (9) and a hydraulic flow assembly (7) for actuating the hydraulic steering cylinder (9), wherein the hydraulic flow assembly (7) is operable using a steering input device (2).

12. The steering system (1) according to claim 10 or 11, wherein the steering system (1) includes a steering input sensor (12) for measuring the position and / or speed of movement (TS) of the steering input device (2).

13. The steering system (1) according to any one of claims 10 to 12, wherein the steering system (1) includes a wheel direction angle sensor (14) for measuring the wheel direction angle of a steerable wheel (101), wherein the steering system (1) is configured to at least change the recovery torque (RTL, RTR) applied to the steering input device (2) by means of the electric motor (5) based on the wheel direction angle.

14. The steering system (1) according to any one of claims 11 to 13, wherein the steering system (1) includes a vehicle speed sensor (13) for measuring vehicle speed, and wherein the steering system (1) is configured to apply restoring force (RTL, RTR) and / or damping force applied to the steering input device (2) by means of the electric motor (5) based on the vehicle speed.

15. The steering system (1) according to any one of claims 11 to 14, wherein the electric motor (5) is an electronically commutated motor having at least three winding phases.

Images