Steering device

Abstract

A steering device (1) to be mounted on a vehicle, wherein the steering device (1) comprises: a power steering unit (12) arranged under a floor (7) of a vehicle cabin (2); a coaxial motor (20) which is provided under the floor (7) of the vehicle cabin (2) and directly above the power steering unit (12) and has an output shaft arranged coaxially to an input shaft of the power steering unit (12); a reaction force motor (30) arranged above the floor (7) of the vehicle cabin (2) and mechanically separated from the coaxial motor (20); a steering shaft (4) which is connected at one end to a steering wheel (3) and at the other end to the reaction force motor (30), the steering wheel (3) being arranged above the floor (7) of the vehicle cabin (2); and a control device which calculates a direction and amount of rotation based on a torque and steering angle of the steering wheel (3), which controls the coaxial motor (20) and the power steering unit (12) to achieve the direction and amount of rotation, and which controls the reaction force motor (30) to exert a reaction force on the steering shaft (4) according to the direction and amount of rotation.

Description

Technical area

[0001] The present disclosure relates to a vehicle-mounted steering apparatus. Technical background

[0002] JP 2007-522 019 A discloses a steering device which is provided with a power steering unit for amplifying a rotational force of a steering shaft, in which, for example, a motor is provided for applying the rotational force to the steering shaft.

[0003] JP 2006-264622 A relates to a power steering device comprising a steering column having a steering shaft that transmits torque of a steering wheel, a steering gear housing disposed outside a passenger compartment and transmitting the torque to steering wheels, an auxiliary motor provided outside the passenger compartment and above the steering gear housing, and a hydraulic power steering mechanism.

[0004] DE 11 2014 004 342 T5 relates to a coaxial motor variable torque differential assembly comprising a motor subassembly, a torque converter subassembly, and a differential subassembly. The motor subassembly includes a motor housing, a motor rear end cover, and a motor front end cover, each disposed at one end and the other of the motor housing, respectively, and a rotor shaft movably mounted on the motor rear end cover and the motor front end cover.

[0005] JP 2004-90686 A relates to a steering device comprising an auxiliary power steering device with an electric auxiliary motor provided for a steering shaft in series with the hydraulically operated power steering device. The electric power steering device is controlled to operate automatically when no oil pressure is supplied.

[0006] JP 2013-10380 A relates to a power steering device comprising a motor capable of adding an assist torque to a rotational torque transmitted from a steering shaft; a steering angle sensor for detecting a steering state and a vehicle speed sensor; a hydraulic oil flow rate control unit for controlling a flow rate of hydraulic oil supplied from a variable capacity pump; a hydraulic oil flow rate estimating unit for estimating a flow rate of the hydraulic oil based on a control amount of the hydraulic oil flow rate control unit; a steering assist force calculating unit that calculates an assist force when the estimated flow rate of the hydraulic oil is equal to or less than a lower limit threshold; and a motor drive control unit for controlling drive of the motor based on the calculated steering assist force.

[0007] US 6 102 150 A relates to a vehicle steering system whose steering handle is operatively connected to a motorized actuator associated with the vehicle's steering wheels via a control system. A hydraulic actuator is provided that can be actuated via two separate hydraulic circuits, which are preferably networked together to allow system circuits from one hydraulic circuit to be used in another hydraulic circuit if necessary.

[0008] JP S62-247 973 A relates to a power steering mechanism in which, when a steering handle is steered, an actuator operating a variable transmission ratio mechanism is driven by a transmission ratio control device.

[0009] US 2005 / 0 205 338 A1 relates to a power steering system for vehicles in which, when a main pump operates in a normal state, oil in an oil tank is supplied to a pump changeover valve in a power steering unit via a main supply channel, and power cylinders provide steering assistance for wheels by using the oil from the main pump. Summary of the inventionTechnical problem

[0010] However, in the configuration of JP 2007- 522 019 A, the motor is also driven as a replacement for the failure of the power steering unit and uses a worm gear mechanism to convert the rotational force, so a motor with higher power and larger dimensions is required.

[0011] An object of this disclosure is to provide a steering apparatus in which the motor can be miniaturized. Solution to the problem

[0012] The problem is solved by a steering device according to claim 1. Advantageous further developments are the subject of the dependent claim. Advantageous effects of the invention

[0013] According to the present disclosure, the motor can be miniaturized. Short description of the characters Fig. 1 schematically illustrates an example of a steering device according to an embodiment of the present disclosure; and Fig. 2 schematically shows an example of a steering device according to a modification of the present disclosure. Description of an embodiment

[0014] An embodiment of the present disclosure will be described in more detail below with reference to the attached drawings.

[0015] The steering device 1 according to the present embodiment will be described with reference to Fig. 1 described. Fig. 1 schematically shows the steering device 1 according to the present illustration. In Fig. 1 FR denotes the front of a vehicle and UP denotes the top of the vehicle.

[0016] The steering device 1 is mounted on the vehicle provided with the vehicle cabin 2. The vehicle is a cab-over type vehicle (e.g., a truck, a bus, a delivery van, or the like) provided with the vehicle cabin 2 above an internal combustion engine (not shown).

[0017] The steering device 1 comprises the steering wheel 3, the first steering shaft 4, the first joint part 5, the second steering shaft 6, the second joint part 10, the third steering shaft 11, the power steering 12, the steering column arm 13, the steering rod 14 and the coaxial motor 20.

[0018] The steering wheel 3 is a device with which a driver performs a turning operation to steer the vehicle.

[0019] The first steering shaft 4 is a rotatable rod-shaped element and is connected at one end to the steering wheel 3 and at the other end to the first joint part 5.

[0020] The first joint part 5 couples the first steering shaft 4 to the second steering shaft 6 at a predetermined angle.

[0021] The first steering shaft 4 is covered on the outer circumference by a cylindrical upper cover (also called a steering hood) 8. Meanwhile, the first joint part 5 is peripherally covered by a cylindrical lower cover (also called a column cover or column sleeve) 9. The upper end of the lower cover 9 is connected to the lower end of the upper cover 8, and the lower end of the lower cover 9 is fixed to the floor (bottom) 7 of the vehicle cabin 2.

[0022] The second steering shaft 6 is a rotatable, rod-shaped member and comprises a shaft (not shown) and a cylindrical member (not shown) surrounding the shaft, which are connected to each other such that they are relatively slidable in the axial direction, whereby the second steering shaft 6 is extendable and retractable, for example.

[0023] The second steering shaft 6 is connected at one end to the first joint part 5 and at the other end to the second joint part 10, which is arranged below the floor 7 (outside the vehicle cabin 2). Specifically, the other end of the second steering shaft 6 is inserted into an opening (not shown) in the floor 7 and connected to the second joint part 10.

[0024] The second joint part 10 couples the second steering shaft 6 to the third steering shaft 11 at a predetermined angle. A portion of the second steering shaft 6 located above the floor 7 (the portion located in the vehicle cabin 2) is covered circumferentially by the lower cover 9.

[0025] The third steering shaft 11 is a rotatable rod-shaped member and is connected at one end to the second joint part 10 and at the other end to an input shaft (not shown) of the power steering unit (also referred to as power steering) 12. The input shaft of the power steering unit 12 is arranged coaxially with the third steering shaft 11.

[0026] The rotational force of the steering wheel 3 is transmitted to the power steering 12 via the first steering shaft 4, the second steering shaft 6 and the third steering shaft 11.

[0027] The power steering unit 12 is located beneath the floor 7 (i.e., outside the vehicle cabin 2). This power steering unit 12 converts the rotational force transmitted as described above into a larger force that pivots the pitman arm 13. Thus, the pitman arm 13 pivots to push or pull the steering rod 14, so that the wheels (not shown) are steered via the articulated arms and tie rods (both not shown).

[0028] The power steering unit 12, for example, is hydraulic, and two main and subsystem oil pumps (not shown) are connected to the power steering unit 12 via one or more oil passages. Thus, even if the main oil pump fails, the subsystem oil pump can handle the operation of the power steering unit 12, allowing the operation of the power steering unit 12 to continue. It should be noted that an oil pump from a single system can also be connected to the power steering unit 12. It should also be noted that the power steering unit 12 can be not only hydraulic but also electric.

[0029] Here, a description will be given of a characteristic configuration of the present embodiment.

[0030] In the present embodiment, the coaxial motor 20 is arranged directly above the power steering unit 12, as shown in Fig. 1 shown.

[0031] The coaxial motor 20 is attached to the third steering shaft 11. An output shaft (not shown) of the coaxial motor 20 is arranged coaxially with the third steering shaft 11. Since the input shaft of the power steering unit 12 is arranged coaxially with the third steering shaft 11 as described above, it can be said that the output shaft of the coaxial motor 20 is arranged coaxially with the input shaft of the power steering unit 12.

[0032] The coaxial motor 20 is driven under the control of an ECU (not shown) to apply the rotational force to the third steering shaft 11. For example, when a driving assistance function is executed, the ECU drives the coaxial motor 20 so that a predetermined amount of rotational force is applied to the third steering shaft 11 at a predetermined time. Examples of the driving assistance function include automatic parking, lane keeping assistance during cruise control, and the like.

[0033] The rotational force exerted on the third steering shaft 11 by the drive of the coaxial motor 20 is transmitted to the power steering 12.

[0034] As described above, the steering device 1 according to the present embodiment is characterized in that the coaxial motor 20 is arranged directly above the power steering 12 (e.g., on the third steering unit 11).

[0035] In the steering device 1 according to the present embodiment, the oil pumps of two systems are connected to the power steering unit 12, so that the power steering unit 12 is fail-safe. This makes it possible to use a smaller, lower-power motor such as the coaxial motor 20. This can improve, for example, the operability of the steering wheel 3. In the above-described configuration of the PTL 1, however, since the motor serves as a backup in the event of a power steering failure, a higher-power and larger-sized motor must be used. Accordingly, there is a problem that the operability of the steering wheel 3 is reduced.

[0036] The present disclosure is not limited to the embodiments described above and can be modified and implemented accordingly without departing from the spirit of the present disclosure. Each modification is described below. [Modification 1]

[0037] The control device of the present publication may be a steer-by-wire system (electric steering system). This example will be described with reference to Fig. 2 described. Fig. 2 schematically shows an exemplary configuration of the steering device 100 according to the present modification.

[0038] The same components of the Fig. 1 and Fig. 2 are provided with the same reference numerals. Furthermore, the floor 7 of the vehicle cabin 2, the steering column lever 13 and the steering rod 14 are omitted in Fig. 2. In addition, dashed arrows show the flow of control signals in Fig. 2 on.

[0039] The steering device 100 includes, in addition to the power steering unit 12 and the coaxial motor 20 described in the exemplary embodiment, also the reaction force motor 30. The power steering unit 12, the coaxial motor 20 and the reaction force motor 30 are each electrically connected to the control device 31, hereinafter also referred to as the control unit, and are controlled on the basis of a control signal from the control device 31.

[0040] In Fig. 2, the steering wheel 3, the first steering shaft 4, the reaction force motor 30 and the control unit 31 are provided in the vehicle cabin 2 (see Fig. 1). The power steering unit 12 and the coaxial motor 20 are located outside the vehicle cabin 2 (see Figure 1). The control unit 31 can also be mounted outside the vehicle cabin 2.

[0041] The output shaft of the coaxial motor 20 is arranged coaxially with the input shaft of the power steering unit 12. Additionally, the coaxial motor 20 is arranged so that it is mechanically separated from the first steering shaft 4 and the reaction force motor 30.

[0042] One end of the first steering shaft 4 is connected to the steering wheel 3 and the other end to the reaction force motor 30.

[0043] The control unit 31 calculates the rotation direction and amount based on the torque and steering angle of the steering wheel 3, which are detected by various sensors (not shown). The control unit 31 then controls the drive of the coaxial motor 20 and the power steering unit 12 to achieve the calculated rotation direction and amount.

[0044] The control device 31 also controls the drive of the reaction force motor 30 so that a reaction force corresponding to the calculated rotation direction and rotation amount is exerted on the first steering shaft 4. [Modification 2]

[0045] The steering apparatus of the present disclosure needs to include, as a minimum configuration, only the power steering unit 12 disposed under the floor 7 of the vehicle cabin 2, and the coaxial motor 20 provided directly above the power steering unit 12 and including the output shaft disposed coaxially with the input shaft of the power steering unit 12. [Modification 3]

[0046] Although the embodiment has been described with reference to the case where the vehicle to which the steering device 1 is mounted is a cab-over-engine type vehicle, the present disclosure is not limited to this example. The steering device 1 can also be mounted on a vehicle with an internal combustion engine in front of or behind the vehicle cabin 2. Summary of Revelation

[0047] The steering device according to the present disclosure is a steering device to be mounted on a vehicle, the steering device comprising: a power steering unit disposed under a floor of a vehicle cabin; and a coaxial motor provided directly above the power steering unit and including an output shaft disposed coaxially with an input shaft of the power steering unit.

[0048] The steering device described above may further comprise: a steering shaft connected at one end to a steering wheel and at the other end to the input shaft of the power steering unit, wherein the steering wheel is arranged above the floor of the vehicle interior in which the output shaft of the coaxial motor may be arranged coaxially with the steering shaft.

[0049] In the steering device described above, the coaxial motor can be controlled together with the power steering unit by a control device so as to achieve a rotation direction and a rotation amount calculated based on the torque and the steering angle of the steering wheel.

[0050] In the steering device described above, the power steering unit may be hydraulic, and multiple oil pumps may be connected to the power steering unit. Industrial applicability

[0051] The steering device of the present disclosure is useful for a steering device of a vehicle. LIST OF REFERENCE SYMBOLS 1, 100 steering device 2 vehicle cabin 3 steering wheel 4 First steering shaft 5 First joint part 6 Second steering shaft 7 Floor 8 Top cover 9 Lower cover 10 Second joint part 11 Third steering shaft 12 Power steering unit 13 Steering column lever 14 Handlebar 20 coaxial motor 30 Reaction force motor 31 Control unit

Claims

[1] A steering device (1) to be mounted on a vehicle, the steering device (1) comprising: a power steering unit (12) arranged under a floor (7) of a vehicle cabin (2); a coaxial motor (20) provided under the floor (7) of the vehicle cabin (2) and directly above the power steering unit (12) and having an output shaft arranged coaxially with an input shaft of the power steering unit (12); a reaction force motor (30) arranged above the floor (7) of the vehicle cabin (2) and mechanically separated from the coaxial motor (20); a steering shaft (4) connected at one end to a steering wheel (3) and at another end to the reaction force motor (30), the steering wheel (3) being arranged above the floor (7) of the vehicle cabin (2); and a control device that calculates a rotation direction and a rotation amount based on a torque and a steering angle of the steering wheel (3), that controls the coaxial motor (20) and the power steering unit (12) to achieve the rotation direction and the rotation amount, and that controls the reaction force motor (30) to apply a reaction force to the steering shaft (4) according to the rotation direction and the rotation amount. [2] The steering device according to claim 1, characterized by , that the power steering unit (12) is hydraulic, and several oil pumps are connected to the power steering unit (12).

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