Steering device

Abstract

This steering device (100) comprises: an angle sensor (134) that acquires the rotation angle of an operation member (210); a reaction force control device (133) that controls the operation of a reaction force motor (135) that applies a steering reaction force, which is a force against a steering force inputted to the operation member (210), to an operation shaft body (211); a steering control device (130) that controls the operation of a steering motor (120) that applies a steering force, which is a force for steering steered wheels (200); a first communication path (141) through which a signal of the angle sensor (134) is transmitted between the angle sensor (134) and the reaction force control device (133) or between the angle sensor (134) and the steering control device (130), and a second communication path (142) through which information is transmitted between the reaction force control device (133) and the steering control device (130). The signal of the angle sensor (134) received by one of the reaction force control device (133) and the steering control device (130) is outputted to the other via the second communication path (142).

Description

Steering device

[0001] The present invention relates to a steering device having a structure in which an operation member and a steering wheel are mechanically separated or separable, and the steering wheel is steered based on a predetermined signal.

[0002] Conventionally, in a so-called steer-by-wire system in which an operation member and a steering wheel are mechanically separated or separable, and the steering wheel is steered based on a signal corresponding to the operation of the operation member, some are provided with an angle sensor for acquiring the rotation angle of the operation member. In Patent Document 1, an angle signal indicating the rotation angle of the operation member is transmitted to a steering ECU (Electronic Control Unit) that controls the steering of the steering wheel and an operation ECU that controls the reaction force applied to the operation member, respectively.

[0003] Japanese Unexamined Patent Application Publication No. 2018-20743

[0004] However, since there are communication systems for transmitting the signal of the sensor that detects the rotation angle of the operation member to the operation ECU and for transmitting the signal of the sensor to the steering ECU, two sets of communication interfaces and communication harnesses are required, the assembly process becomes complicated, and the weight increases.

[0005] The present invention has been made in view of the above problems, and provides a steering device capable of suppressing the number of communication systems.

[0006] One steering device according to the present invention is a steering device having a structure in which an operating member and a steering wheel are mechanically separated or separable, and comprises: an angle sensor that acquires the rotation angle of an operating shaft that rotatably holds the operating member; a reaction force control device that controls the operation of a reaction force motor that provides a steering reaction force, which is a force that opposes the steering force input to the operating member, to the operating shaft; a steering control device that controls the operation of a steering motor that provides a steering force, which is a force that steers the steering wheel; a first communication path through which the signal of the angle sensor is transmitted between the angle sensor and the reaction force control device, or between the angle sensor and the steering control device; and a second communication path through which information is transmitted between the reaction force control device and the steering control device, wherein the signal of the angle sensor received by one of the reaction force control device and the steering control device is output to the other via the second communication path.

[0007] According to the present invention, the signal from an angle sensor indicating the rotation angle of the operating member is transmitted to one of the reaction force control device and the steering control device, and the transmitted signal is then transmitted to the other control device using a communication system between the control devices, thereby reducing the number of communication paths.

[0008] Figure 1 shows the overall configuration of the steering system. Figure 2 shows the overall configuration of another example of the steering system 1. Figure 3 shows the overall configuration of another example of the steering system 2. Figure 4 shows the overall configuration of another example of the steering system 3.

[0009] The following describes embodiments of the steering device according to the present invention with reference to the drawings. Note that the following embodiments are examples provided to illustrate the present invention and are not intended to limit it. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, formulas, the content of each step in the method, and the order of each step shown in the following embodiments are examples and may include content not described below. Furthermore, geometric expressions such as parallel and orthogonal may be used, but these expressions do not indicate mathematical rigor and include substantially acceptable errors and deviations. Similarly, expressions such as simultaneous and identical also include substantially acceptable ranges.

[0010] Furthermore, the drawings are schematic diagrams that have been appropriately emphasized, omitted, or had their proportions adjusted to illustrate the present invention, and therefore differ from the actual shapes, positional relationships, and proportions. Also, the X, Y, and Z axes shown in the drawings represent orthogonal coordinates arbitrarily set for the purpose of explaining the drawings. In other words, the Z axis is not necessarily an axis along the vertical direction, and the X and Y axes are not necessarily located in the horizontal plane.

[0011] Furthermore, in the following, multiple inventions may be described comprehensively as a single embodiment. Also, some of the content described below is described as an optional component relating to the present invention.

[0012] Figure 1 shows the overall configuration of the steering device 100. The steering device 100 is a system that can steer the steering wheels 200 mounted on a vehicle such as a passenger car based on signals output by operating an operating member 210. The steering device 100 includes a steering motor 120, an angle sensor 134, a reaction force motor 135, a reaction force control device 133, a steering control device 130, a first communication path 141, and a second communication path 142. In this embodiment, the steering device 100 includes an operating member 110, a first power supply source 151, and a second power supply source 152. The steering device 100 can be exemplified as one in which the operating member 210 and the steering wheels 200 are mechanically separated at all times, or in which the mechanical connection between the operating member 210 and the steering wheels 200 can be separated by a clutch or the like. In this embodiment, the operating member 210 and the steering wheel 200 are not connected by mechanical elements such as links, and the steering wheel 200 is steered based solely on signals, using a so-called linkless steer-by-wire system.

[0013] The operating member 110 is a member that operates in response to the output of the steering motor 120 to generate thrust and steer the steering wheels 200. The type of operating member 110 is not limited, but in this embodiment, the operating member 110 is a rack bar, and rack teeth are provided at one of the positions in the longitudinal direction. The rack bar generates thrust in the axial direction in response to the output of the steering motor 120 and steers the two steering wheels 200 simultaneously via tie rods or the like connected to both ends of the rack bar.

[0014] The angle sensor 134 is a sensor that acquires the rotation angle of the operating shaft 211 that rotatably holds the operating member 210. In this embodiment, the angle sensor 134 acquires the absolute rotation angle of the operating shaft 211. The absolute rotation angle is information that allows us to acquire, for example, how many rotations the operating member 210 has made from its zero position (neutral position), and whether it is a clockwise or counterclockwise rotation. The type of angle sensor 134 is not limited, but an example can be given of an angle sensor 134 that acquires the absolute rotation angle based on the phase difference between the second gear and the third gear, by meshing a second gear and a third gear with different numbers of teeth with a first gear that rotates synchronously with the operating shaft 211.

[0015] In this embodiment, a torque sensor 136 is attached to the operating shaft 211, which detects the torque when the operator rotates the operating member 210.

[0016] The reaction force control device 133 is a so-called ECU that controls the operation of a reaction force motor 135, which applies a steering reaction force to the operating shaft 211, which is a force that opposes the steering force input to the operating member 210, based on the torque detected by the torque sensor 136. The reaction force motor 135 is equipped with an angle sensor that detects the rotation angle within one rotation and a motor turn counter (not shown) that detects which rotation it is. The reaction force control device 133 performs feedback control to the reaction force motor 135 based on the rotation angle of which rotation it is. Since the rotation of the output shaft of the reaction force motor 135 and the rotation of the operating shaft 211 are synchronized, the angle sensor and motor turn counter equipped with the reaction force motor 135 can output information indicating the rotation angle of the operating shaft 211 and which rotation it is.

[0017] The steering control device 130 is a so-called ECU that controls the operation of the steering motor 120, which provides steering force to the operating member 110, causing the steering wheels 200 to turn. The steering motor 120 is an electric motor that simultaneously rotates a pair of steering wheels via the operating member 110. The mechanism by which the steering motor 120 operates the operating member 110 is not limited, but in this embodiment, a pinion shaft that meshes with the rack teeth provided on the rack bar is arranged. In addition, a reduction gear that reduces the rotation of the steering motor 120 and rotates the pinion shaft is attached to the pinion shaft. Through these mechanisms, the steering motor 120 operates the operating member 110. The steering motor 120, like the reaction force motor 135, is equipped with an angle sensor and a motor turn counter (not shown), and can output information indicating the rotation angle of the output shaft of the steering motor 120 and which rotation it is.

[0018] The first communication path 141 is a communication path through which the signal from the angle sensor 134 is transmitted between the angle sensor 134 and the reaction force control device 133, or between the angle sensor 134 and the steering control device 130. In this embodiment, the first communication path 141 transmits the signal from the angle sensor 134 between the angle sensor 134 and the steering control device 130. The torque sensor 136 transmits a signal indicating torque to the reaction force control device 133 via the same type of communication path as the first communication path 141. The type of the first communication path 141 is not limited, but in this embodiment, the first communication path 141 is a communication path through which the signal from the angle sensor 134 cannot be branched and transmitted. An example of a communication path through which branching and transmission is not possible is SENT (Single Edge Nibble Transmission) communication. SENT communication is a communication protocol for accurately and cost-effectively transmitting sensor data to the ECU.

[0019] The second communication path 142 is a communication path through which information is transmitted between the reaction force control device 133 and the steering control device 130. The type of the second communication path 142 is not limited, but in this embodiment, the second communication path 142 can be exemplified by a so-called CAN (Controller Area Network) or a communication path similar to CAN, which uses the standard protocol of the in-vehicle network to perform communication between the control devices. Specifically, each communication path is implemented by a communication cable.

[0020] The first power source 151 is a battery that supplies power to the angle sensor 134. In this embodiment, the first power source 151 is not directly connected to the angle sensor 134, but is connected to the steering control device 130. The steering control device 130 and the angle sensor 134 are connected by a power supply wire, and the first power source 151 supplies power to the angle sensor 134 via the steering control device 130. The supply voltage of the first power source 151 is higher than the rated voltage at which the angle sensor 134 operates, and since the rated voltage of the angle sensor 134 and the rated voltage of the steering control device 130 are the same, the voltage stepped down by the step-down device in the steering control device 130 can also be supplied to the angle sensor 134.

[0021] The second power source 152 is a battery that supplies power to the reaction force control device 133. By providing separate power sources for the steering control device 130 and the reaction force control device 133, redundancy can be ensured.

[0022] Next, the operation of the steering system 100 will be explained. During normal manual operation, the steering motor 120 operates based on information indicating the rotation angle of the reaction force motor 135, which is transmitted from the reaction force control device 133 when the driver rotates the operating member 210, causing the steering wheels 200 to turn.

[0023] When starting the vehicle, the steering control device 130 and the reaction force control device 133 check whether the information indicating the steering angle of the steering wheel 200 is available. If it is determined that the correspondence between the absolute rotation angle of the operating shaft 211 and the angle sensor and motor turn counter of the reaction force motor 135 is incorrect, the following calibration is performed. The angle sensor 134 transmits a signal indicating the absolute rotation angle to the steering control device 130 via the first communication path 141, and to the reaction force control device 133 via the second communication path 142. Based on the transmitted signals, the steering control device 130 and the reaction force control device 133 calibrate the zero position (equivalent to straight-ahead movement) indicated by the angle sensor and motor turn counter to match the zero position of the absolute rotation angle of the operating member 210. For subsequent control, the value obtained by converting the integrated output of the calibrated motor turn counter to a reduction ratio is used as the rotation angle of the operating member 210. Furthermore, one possible cause for a mismatch between the absolute rotation angle of the operating shaft 211 and the angle sensor and motor turn counter of the reaction motor 135 is when the vehicle's power is interrupted, such as during battery replacement.

[0024] Furthermore, if a malfunction occurs in the reaction force control device 133, the angle sensor of the reaction force motor 135, the motor turn counter of the reaction force motor 135, or the second communication path 142, as an emergency measure, the steering motor 120 is driven based on the value transmitted from the angle sensor 134 to steer the steering wheels 200. This makes it possible to move the vehicle to a safe place such as the shoulder of the road even if a malfunction occurs in the information that is normally used.

[0025] It should be noted that the present invention is not limited to the embodiments described above. For example, other embodiments of the present invention may be realized by arbitrarily combining the components described herein, or by excluding some of the components. Furthermore, modifications obtained by applying various modifications to the above embodiments that a person skilled in the art could conceive of without departing from the spirit of the present invention, that is, the meaning indicated by the wording in the claims, are also included in the present invention.

[0026] For example, the first communication path 141 may transmit signals from the angle sensor 134 between the angle sensor 134 and the reaction force control device 133, as shown in Figure 2. During normal manual operation, the steering motor 120 operates and the steering wheels 200 turn based on information indicating the rotation angle of the reaction force motor 135, which is transmitted from the reaction force control device 133 when the driver rotates the operating member 210.

[0027] On the other hand, if calibration is required, the angle sensor 134 transmits a signal indicating the absolute rotation angle to the reaction force control device 133 via the first communication path 141. Based on the transmitted signal, the reaction force control device 133 calibrates the zero position (equivalent to straight-line movement) indicated by the angle sensor and the motor turn counter to coincide with the zero position of the absolute rotation angle of the operating member 210.

[0028] Furthermore, as shown in Figure 3, the steering system 100 includes a first steering motor 121 and a second steering motor 122 as steering motors 120, and a first steering control device 131 and a second steering control device 132 as steering control devices 130. The first communication path 141 transmits signals from the angle sensor 134 between the angle sensor 134 and the first steering control device 131, and signals are transmitted between the reaction force control device 133 and the second steering control device 132 via the third communication path 143. The first power supply source 151 supplies power to the first steering motor 121 and the first steering control device 131, or may supply power directly from the first power supply source 151 to the angle sensor 134. The second power supply source 152 may supply power to the second steering motor 122 and the second steering control device 132. In this case, during normal manual operation, the first steering motor 121 and the second steering motor 122 operate based on information indicating the rotation angle of the reaction motor 135, which is transmitted from the reaction force control device 133 to the second steering control device 130 via the third communication path 143 when the driver rotates the operating member 210, and information indicating the rotation angle of the reaction motor, which is transmitted from the second steering control device 132 to the first steering control device 131 via the second communication path 142, causing the steering wheel 200 to turn.

[0029] Furthermore, the steering device 100 can also be applied to a steer-by-wire system that independently steers multiple steering wheels 200, as shown in Figure 4.

[0030] (Summary) The steering device 100 of the first embodiment is a steering device 100 having a structure in which the operating member 210 and the steering wheels 200 are mechanically separated or separable, and includes an angle sensor 134 that acquires the rotation angle of the operating shaft 211 that rotatably holds the operating member 210, a reaction force control device 133 that controls the operation of a reaction force motor 135 that gives a steering reaction force, which is a force that resists the steering force input to the operating member 210, to the operating shaft 211, and a steering motor 12 that gives a steering force, which is a force that turns the steering wheels 200 The system includes a steering control device 130 that controls the operation of 0, a first communication path 141 through which signals from the angle sensor 134 are transmitted between the angle sensor 134 and the reaction force control device 133, or between the angle sensor 134 and the steering control device 130, and a second communication path 142 through which information is transmitted between the reaction force control device 133 and the steering control device 130. Signals from the angle sensor 134 received by either the reaction force control device 133 or the steering control device 130 are output to the other via the second communication path 142.

[0031] According to the first embodiment, the angle signal from the angle sensor 134 is transmitted only to the steering control device 130 via the first communication path 141, and the signal from the angle sensor 134 is transmitted to the reaction force control device 133 only via the second communication path 142. Therefore, it is not necessary to transmit the signal from the angle sensor 134 to both the steering control device 130 and the reaction force control device 133, which reduces the number of parts used in the steering device 100 and simplifies the manufacturing process. Furthermore, since the angle sensor 134 is connected to the steering control device 130 via the first communication path 141 and the reaction force control device 133 is connected via the second communication path 142, even in the event of an abnormality where steering signals from the angle sensor on the reaction force motor 135 and the reaction force control device 133 via the motor turn counter do not reach the steering control device 130, the steering wheel 200 can be rotated and steering can be maintained based on the signal indicating the rotation angle of the operating member 210 output from the angle sensor 134.

[0032] The steering device 100 of the second embodiment includes the first embodiment and comprises a first power supply source 151 that supplies power to the angle sensor 134 and a second power supply source 152 that supplies power to the reaction force control device 133.

[0033] According to the second embodiment, redundancy is also ensured for the power supply source, and even if power is not supplied to the reaction force control device 133, steering can be performed based on the signal indicating the rotation angle of the operating member 210 output from the angle sensor 134.

[0034] The steering device 100 of the third embodiment includes the second embodiment, wherein the first power supply source 151 is connected to the steering control device 130, and power is supplied to the angle sensor 134 via the steering control device 130.

[0035] According to the third embodiment, it is not necessary to separately provide a converter or the like to step down the voltage to a voltage suitable for the angle sensor 134, and the number of components can be reduced.

[0036] The steering device 100 of the fourth embodiment includes the second or third embodiment and comprises a first steering motor 121 and a second steering motor 122 as steering motors 120, a first steering control device 131 and a second steering control device 132 as steering control devices 130, a first communication path 141 transmits signals from the angle sensor 134 between the angle sensor 134 and the steering control device 130, a first power supply source 151 supplies power to the first steering motor 121 and the first steering control device 131, and a second power supply source 152 supplies power to the second steering motor 122 and the second steering control device 132.

[0037] According to the fourth embodiment, even if a malfunction occurs in the first power supply 151 and the first steering motor 121 does not operate, steering can be performed by operating the second steering motor 122 based on the signal indicating the rotation angle of the operating member 210 output from the reaction force control device 133. Furthermore, even if a malfunction occurs in the power supply from the second power supply 152, steering can be performed by operating the first steering motor 121 based on the angle signal from the angle sensor 134. Therefore, even if a malfunction occurs in one of the steering control devices, such as a malfunction in either the first power supply 151 or the second power supply 152, steering can still be performed using the other steering control device.

[0038] The technology according to the present invention can be used in a steering system that can steer each steering wheel based on a signal.

[0039] 100... Steering device, 110... Operating member, 120... Steering motor, 121... First steering motor, 122... Second steering motor, 130... Steering control device, 131... First steering control device, 132... Second steering control device, 133... Reaction force control device, 134... Angle sensor, 135... Reaction force motor, 136... Torque sensor, 141... First communication path, 142... Second communication path, 143... Third communication path, 151... First power supply source, 152... Second power supply source, 200... Steering wheel, 210... Operating member, 211... Operating shaft

Claims

1. A steering device having a structure in which an operating member and a steering wheel are mechanically separated or separable, comprising: an angle sensor for acquiring the rotation angle of an operating shaft that rotatably holds the operating member; a reaction force control device for controlling the operation of a reaction force motor that applies a steering reaction force, which is a force resisting the steering force input to the operating member, to the operating shaft; a steering control device for controlling the operation of a steering motor that applies a steering force, which is a force that turns the steering wheel; a first communication path through which the signal of the angle sensor is transmitted between the angle sensor and the reaction force control device, or between the angle sensor and the steering control device; and a second communication path through which information is transmitted between the reaction force control device and the steering control device, wherein the signal of the angle sensor received by one of the reaction force control device and the steering control device is output to the other via the second communication path.

2. The steering device according to claim 1, further comprising: a first power supply source that supplies power to the angle sensor; and a second power supply source that supplies power to the reaction force control device.

3. The steering device according to claim 2, wherein the first power supply source is connected to the steering control device, and power is supplied to the angle sensor via the steering control device.

4. The steering device according to claim 2, comprising a first steering motor and a second steering motor as the steering motor, a first steering control device and a second steering control device as the steering control device, the first communication path transmits the signal of the angle sensor between the angle sensor and the first steering control device, the first power supply source supplies power to the first steering motor and the first steering control device, and the second power supply source supplies power to the second steering motor and the second steering control device.

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