Wheel steering system

Abstract

To provide a wheel steering device with a simple configuration that can suppress increases in manufacturing costs and weight, minimizes the need to conserve installation space within the vehicle body, and allows for easy adjustment of the wheel direction. [Solution] A wheel steering device 100 having a steering unit 110 and a control unit, wherein the steering unit 110 has a main body 111, a steering transmission member 112 that rotatably connects the wheel T1 and the main body 111, and a steering mechanism 113, the steering mechanism 113 has a transmission strip 114, a transmission rotating body 115 that contacts the transmission strip 114 and moves forward and backward, and a drive source 116 that is rotatably connected to the transmission rotating body 115 in both forward and reverse directions, the steering transmission member 112 is provided with a pair of transmission connection parts 120, both ends of the transmission strip 114 are connected to the pair of transmission connection parts 120 respectively, the drive source 116 is connected to the main body 111, and the control unit is configured to control the rotation of the transmission rotating body 115.

Description

Technical Field

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[0001] The present invention relates to a wheel steering device having a steering unit provided between a vehicle body and wheels for steering the wheels and a control unit.

Background Art

[0002] Conventionally, as a wheel steering device for steering wheels of an automobile or the like, for example, a wheel steering device (steering device 6) of a steering system described in Patent Document 1 is known.

[0003] The wheel steering device (steering device 6) known from this Patent Document 1 drives an actuator 7 based on an output signal read by a sensor of the operation of the steering wheel 2 of the steering device 3, and meshes with a pinion rotated by the actuator 7. By moving the rack gear left and right, the directions of a pair of left and right steering wheels 5 connected via tie rods respectively connected to the left and right ends of the rack gear are changed to enable steering.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the wheel steering devices known from the above patent documents and the like still had room for improvement.

[0006] That is, in the wheel steering devices known from Patent Document 1 and the like, since the left and right steering wheels are interlocked and their directions are changed by the movement of a rack gear connected via tie rods, when there are defects or the like in the balance of the directions of the left and right steering wheels, there is a risk that it may be difficult to easily adjust the directions of the left and right steering wheels. Furthermore, because the rack gear needs to be positioned between the left and right steering wheels, spanning the vehicle body, the space required for installing the steering mechanism becomes large, which could severely restrict the space available for other components. In particular, if suspension is connected to each of the left and right steering wheels to mitigate shocks during driving, thereby individually mitigating the shocks to each steering wheel, the structure of the connection between the left and right steering wheels itself becomes more complex, potentially increasing costs and weight, and complicating the layout of surrounding components within the vehicle body, including the wheel steering system.

[0007] Furthermore, there was a risk that the manufacturing costs and weight would increase due to the larger size of the components that make up the steering mechanism.

[0008] The present invention aims to solve these problems by providing a wheel steering device that has a simple configuration, can suppress increases in manufacturing costs and weight, does not impede installation space within the vehicle body, and allows for easy adjustment of the direction of the wheels. [Means for solving the problem]

[0009] The wheel steering device of the present invention is a wheel steering device comprising a steering unit provided between the vehicle body and the wheel for steering the wheel, and a control unit, wherein the steering unit comprises a main body connected to the vehicle body, a steering transmission member connecting the wheel and the main body so as to be rotatable relative to each other on a steering shaft, and a steering mechanism for steering the steering transmission member, wherein the steering mechanism comprises a transmission strip, a transmission rotating body that contacts the transmission strip and moves forward and backward, and a drive source that connects the transmission rotating body so as to be rotatable in forward and reverse directions with respect to the transmission rotating shaft, which is the rotation axis of the transmission rotating body, as the center of rotation, wherein the steering transmission member is provided with at least a pair of transmission connection parts arranged to straddle a straight line connecting the intersection point of the steering transmission member with the steering shaft and the contact point between the transmission rotating body and the transmission strip, the ends of the transmission strip are respectively connected to the pair of transmission connection parts, the drive source is connected to the main body, and the control unit is configured to control the rotation of the transmission rotating body by the drive source, thereby solving the above problem. [Effects of the Invention]

[0010] The wheel steering device according to claim 1 comprises a steering mechanism having a transmission strip, a transmission rotating body that contacts the transmission strip and moves forward and backward, and a drive source that connects the transmission rotating body so that it can rotate in forward and reverse directions around the transmission rotating shaft as the center of rotation. The steering transmission member is provided with a pair of transmission connection parts arranged to straddle a straight line connecting the intersection point of the steering transmission member with the steering shaft and the contact point between the transmission rotating body and the transmission strip. Both ends of the transmission strip are connected to the pair of transmission connection parts, respectively. The drive source is connected to the main body. The control unit is configured to control the rotation of the transmission rotating body by the drive source. By rotating the transmission rotating body in forward and reverse directions and moving the transmission strip forward and backward, the steering transmission member can be rotated around the steering shaft, thereby changing the direction of the wheel connected to the steering transmission member. Furthermore, since one steering unit steers one wheel, even when steering a pair of wheels on the left and right, as in an automobile, it is sufficient to place an independent steering unit for each wheel. This means that the steering unit can be installed by securing space only around the wheel, eliminating the need for large components to connect the pair of wheels, thus not occupying a large amount of space inside the vehicle body, and preventing the device configuration and the layout with surrounding components inside the vehicle from becoming complicated. Furthermore, it does not require a large structural member that crosses the vehicle body between the left and right pair of wheels, allowing the steering unit to be constructed inexpensively. Furthermore, since the steering transmission member is moved back and forth to steer the wheel, the steering unit itself does not move significantly, allowing for a more compact and simpler design compared to a configuration where the left and right steering wheels are connected via tie rods or the like.

[0011] According to the configuration described in claim 2, since the transmission strip is made up of a chain and the transmission rotating body is made up of a sprocket, the error in the steering angle with respect to the amount of rotation of the transmission rotating body is only a small amount within the range of meshing between the chain and the sprocket, and stable steering can be maintained for a long period of time. Furthermore, when the chain or sprockets wear out, replacing them with chains and sprockets of the same specifications allows for easy and stable steering without the need for extensive adjustments. According to the configuration described in claim 3, the steering mechanism is provided with a tensioner that presses against the transmission string, and the tensioner is connected to the main body. Therefore, even when the transmission string, which is made of a chain, stretches slightly and slack occurs, the tensioner can always apply tension to the transmission string by pressing against it, thereby preventing backlash.

[0012] According to the configuration described in claim 4, since the tensioner and the drive source are fixed to the main body via an interlocking fixing member, the tensioner and the drive source can be easily aligned to the optimal installation position of the transmission string by changing the shape of the interlocking fixing member, and the positional discrepancy between the tensioner and the drive source can be minimized. According to the configuration described in claim 5, the main body is pivotably connected to the vehicle body via a pivot shaft, and the steering transmission member is connected to the vehicle body via a cushioning member. Therefore, even when there are uneven roads or obstacles that can be overcome, the wheels can pivot together with the steering unit around the pivot shaft, and the cushioning member reduces the momentum during the pivoting motion, thereby maintaining stable driving.

[0013] According to the configuration described in claim 6, the control unit is configured to control the rotation of the transmission rotating body by the drive source based on an operation signal from the vehicle's operating section. For example, when a driver riding in the vehicle operates a handle provided on the operating section, the control unit receives an operation signal from the operating section corresponding to the amount of the handle operation, and drives the drive source to steer the wheels so that the steering angle of the wheels corresponds to the amount of the handle operation. According to the configuration described in claim 7, a pair of wheels are provided on the left and right sides of the vehicle body, one steering unit is provided for each of the multiple steering target wheels, and the control unit is configured to control multiple steering units simultaneously. Therefore, the control unit can steer the left and right pair of steering units in conjunction, and the steering angle of one of the left and right pair of wheels can be easily adjusted individually without affecting the other wheel of the left and right pair.

[0014] According to the configuration described in claim 8, the steering unit further includes a detection unit capable of detecting the steering angle of the steering transmission member, and the control unit is configured to control the rotation of the transmission rotating body by the drive source based on the information of the steering angle of the steering transmission member detected by the detection unit. Therefore, even if a discrepancy occurs between the steering angle defined by the control unit and the actual steering angle of the wheels, the control unit can automatically correct the discrepancy in the steering angle by comparing the information of the actual steering angle from the detection unit with the steering angle defined by the control unit, thereby maintaining even more stable and accurate steering. [Brief explanation of the drawing]

[0015] [Figure 1] A schematic top view showing a vehicle P equipped with a wheel steering device 100 according to one embodiment of the present invention. [Figure 2] A top view of a wheel steering device 100 according to one embodiment of the present invention. [Figure 3] Front view of the wheel steering device 100 according to an embodiment of the present invention. [Figure 4] Side cross-sectional view of the wheel steering device 100 according to an embodiment of the present invention. [Figure 5] Top view showing the state where the front wheel T1 is steered by the wheel steering device 100 according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the wheel steering device 100 according to an embodiment of the present invention will be described based on the drawings. For the sake of explanation, the control unit is not shown.

[0017] The wheel steering device 100 according to an embodiment of the present invention is attached between the front wheel T1, which is a wheel of the traveling vehicle P, and the vehicle body F, as shown in FIGS. 1 to 4. Note that a configuration similar to the wheel steering device 100 is also attached between the front wheel T2 and the vehicle body F on the front wheel T2 side, and the front wheels T1 and T2 can be steered in conjunction with each other by a common control unit. Further, the rear wheels T3 and T4 are attached to the vehicle body F so as to be rotatable about the central axes of the rear wheels T3 and T4 without passing through a configuration similar to the wheel steering device 100.

[0018] The wheel steering device 100 according to an embodiment of the present invention includes a steering unit 110 provided between the vehicle body F and the front wheel T1 for steering the front wheel T1, and a control unit. The steering unit 110 has a main body portion 111 connected to the vehicle body F, a steering transmission member 112 that connects the front wheel T1 and the main body portion 111 so as to be relatively rotatable about a steering shaft 123, and a steering mechanism 113 that steers the steering transmission member 112.

[0019] The steering mechanism 113 includes a transmission strip 114 made of a chain that connects both ends to a transmission connection part 120, which will be described later; a transmission rotating body 115 made of a sprocket that meshes with the transmission strip 114 and moves the transmission strip 114 forward and backward; a drive source 116 that connects the transmission rotating body 115 so that it can rotate in both forward and reverse directions with the transmission rotating shaft 116a as the center of rotation; and a tensioner 117 that presses the transmission strip 114 with a pressing part 117a. Furthermore, the pressing portion 117a of the tensioner 117 is biased in a direction that presses toward the transmission strip 114.

[0020] The steering transmission member 112 has an upper section 112a, a lower section 112b, and an intermediate connecting section 112c that connects the upper section 112a and the lower section 112b. The intermediate connection section 112c is rotatably connected to the front wheel T1 via the connecting shaft 123.

[0021] The upper section 112a has transmission connection sections 120 (first transmission connection section 120a, second transmission connection section 120b) at both ends along the rotational direction of the front wheel T1. The upper surface of the upper section 112a is connected to the cushioning member 121, and the lower section 112b is connected to the main body 111 with the steering shaft 123 as the axis of rotation. Between the main body 111 and the lower section 112b, a steering angle detection unit S capable of detecting the actual steering angle of the steering transmission member 112 is provided, and the steering angle detection unit S is configured to transmit the detected information of the actual steering angle of the steering transmission member 112 to the control unit.

[0022] The main body 111 is pivotably connected to the vehicle body F with the pivot shaft 118 as the pivot center, and the drive source 116 and tensioner 117 are fixed at a predetermined height via the interlocking fixing member 122. This allows the tensioner 117 and drive source 116 to be easily aligned to the optimal installation position of the transmission string 114 simply by changing the shape of the interlocking fixing member 122, while minimizing the positional discrepancy between the tensioner 117 and the drive source 116.

[0023] Next, a method for steering the front wheel T1 using a wheel steering device 100 according to one embodiment of the present invention will be explained with reference to Figures 1 to 5. In addition, a vehicle P to which a wheel steering device 100 according to one embodiment of the present invention is attached transmits an operation signal from an operating unit (not shown) to a control unit by the driver operating a steering wheel unit (not shown).

[0024] First, the driver, who is riding in the vehicle P, operates the steering unit (not shown) so that the vehicle P turns to the left. At this time, the control unit (not shown) transmits an operation signal to the control unit that changes according to the amount of operation of the steering wheel unit (not shown) by the driver, and the control unit determines the target steering angle based on the received operation signal.

[0025] Based on the information of the determined target steering angle, the control unit operates the forward and reverse rotation of the drive source 116 to rotate the transmission rotor 115, and sends the transmission strip 114 that is meshed with the transmission rotor 115 from the second transmission connection part 120b side to the first transmission connection part 120a side. As a result, the steering transmission member 112 receives a force such that the second transmission member 120b is pulled by the transmission strip 114, and rotates around the steering shaft 123 as the center of rotation until it reaches the target steering angle. The front wheel T1 connected to the steering transmission member 112 also changes direction together with the steering transmission member 112 until it reaches the target steering angle.

[0026] At this time, the steering angle detection unit S is configured to transmit information on the actual steering angle of the steering transmission member 112 that it has detected to the control unit. Therefore, the control unit can compare the target steering angle with the information on the actual steering angle of the steering transmission member 112 and adjust the rotation angle of the transmission rotor 115 via the drive source 116 so that the steering transmission member 112 reliably reaches the target steering angle. Furthermore, since there is virtually no time lag between operating the steering unit (not shown) and the front wheels T1 beginning to turn towards the target steering angle via the control unit (not shown) and control unit, the driver can operate the vehicle P without any discomfort.

[0027] Furthermore, since the control unit is configured to also steer the wheel steering device on the front wheel T2 side, the driver can steer the front wheel T1 and the front wheel T2 in conjunction by operating the steering wheel unit (not shown). Furthermore, if the control unit is configured to detect information on road surface conditions, vehicle speed, acceleration / deceleration, and cornering state, the steering angles of the front wheels T1 and T2 can be individually adjusted in response to the operation of the steering unit (not shown) according to the road surface conditions and the state of the vehicle. This allows for the automatic selection of the optimal orientation of the front wheels T1 and T2 according to the driving conditions.

[0028] As described above, the wheel steering device 100 according to one embodiment of the present invention can steer the front wheels T1 and T2 to the optimal steering angle in response to the driver's operation of a steering wheel unit (not shown) to change direction. Furthermore, since each of the front wheels T1 and T2, which are arranged side by side, is provided with a wheel steering device, and each wheel steering device is configured to adjust the steering by a control unit, it is only necessary to secure space for the wheel steering devices around each of the front wheels T1 and T2, and there is no need to use large components to connect the front wheels T1 and T2 and transmit power, so that it does not occupy a large amount of space inside the vehicle body F.

[0029] Furthermore, because it does not require large components to connect the front wheel T1 to the front wheel T2 and transmit power, the manufacturing cost of the wheel steering system itself can be kept low, and the weight can be reduced, thus improving the fuel efficiency of the vehicle. Furthermore, since the steering transmission member 112 and the front wheel T1 are steered by moving the transmission strip 114, which has both ends connected to the transmission connection parts 120 (first transmission connection part 120a, second transmission connection part 120b), the steering unit 110 itself does not move significantly, and can be designed in a more compact and simple configuration compared to a configuration in which the left and right front wheels T1 and T2 are connected via tie rods or the like.

[0030] Furthermore, since the transmission string 114 is composed of a chain and the transmission rotating body 115 is composed of a sprocket, the error in the steering angle of the front wheel T1 with respect to the amount of rotation of the transmission rotating body 115 is limited to a small amount within the range of meshing between the chain and the sprocket, allowing stable steering to be maintained for a long period of time. Furthermore, even when the transmission strings 114 or the rotating transmission body 115 wear out, the steering of the front wheel T1 can be easily stabilized without the need for extensive adjustments by replacing them with a chain and sprocket of the same specifications.

[0031] Furthermore, because the tensioner 117 constantly presses against the transmission string 114, which is composed of a chain, even if the transmission string 114 stretches slightly, tension is always applied to the transmission string 114, thus preventing backlash. Furthermore, since the main body 111 is pivotably connected to the vehicle body F via a pivot shaft 118, and the steering transmission member 112 is connected to the vehicle body F via a buffer member 121, even on roads with steps or obstacles that can be overcome, the front wheels T1 can pivot together with the steering unit 110 around the pivot shaft 118, and the buffer member 121 reduces the momentum during the pivoting, thereby maintaining stable driving. Furthermore, since the steering unit 110 oscillates in conjunction with the main body 111, the steering unit 110 can perform its steering function even when oscillating, thus maintaining even more stable driving.

[0032] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the present invention as described in the claims.

[0033] In the embodiments described above, it was assumed that wheel steering devices were attached to the front wheels located on the left and right sides of the front of the vehicle body. However, the mounting locations of the wheel steering devices and the configuration of the vehicle are not limited to these. For example, wheel steering devices may be attached to the rear wheels, or to a single front wheel located at the front of the vehicle body. Furthermore, although the above-described embodiment was explained in which the transmission strip is composed of a chain and the transmission rotating body is composed of a sprocket, the configuration of the transmission strip and the transmission rotating body is not limited to this. For example, the transmission strip may be composed of a belt, and the transmission rotating body may be composed of a pulley that moves back and forth on the belt-composed transmission strip by frictional force.

[0034] Furthermore, in the embodiments described above, the control unit was described as receiving an operation signal transmitted from the operating unit when the driver operates the steering wheel unit and operating the drive source to steer the front wheels. However, the operation signals received by the control unit are not limited to this. For example, the control unit may be configured to receive an operation signal automatically transmitted by the autonomous vehicle, rather than by the driver, and operate the drive source to steer the front wheels. Alternatively, the control unit may be operated by the driver using a wireless controller that can communicate with the control unit, without a steering wheel unit mounted on the vehicle body. [Explanation of symbols]

[0035] 100 ··· Wheel steering system 110 ··· Steering unit 111 ··· Main body 112 ··· Steering transmission member 112a... Upper section 112b ... lower section 112c ··· Intermediate connection section 113 ··· Steering mechanism 114 ··· Transmissible stria 115 ··· Transmission Rotating Body 116 ··· Power source 116a ··· Transmission rotating shaft 117 ··· Tensioner 117a ··· Pressing part 118 ··· Oscillating axis 119 ··· Connecting shaft 120 ···Transmission connection section 120a ··· First transmission connection section 120b ··· Second transmission connection section 121... Cushioning material 122 ··· Interlocking fixing member 123 ··· Steering shaft F ··· Vehicle body P ··· Vehicles in operation T1, T2... Front wheels T3, T4... Rear wheel S ··· Steering angle detection unit

Claims

1. A wheel steering device comprising a steering unit and a control unit, which are provided between the vehicle body and the wheels to steer the wheels, The steering unit comprises a main body connected to the vehicle body, a steering transmission member that connects the wheels and the main body so as to be rotatable relative to each other via a steering shaft, and a steering mechanism that steers the steering transmission member. The steering mechanism comprises a transmission strip, a transmission rotating body that contacts the transmission strip and moves forward and backward, and a drive source that connects the transmission rotating body so that it can rotate in both forward and reverse directions around the transmission rotating shaft, which is the rotation axis of the transmission rotating body. The steering transmission member is provided with at least a pair of transmission connection parts arranged to straddle a straight line connecting the intersection point of the steering transmission member with the steering shaft and the point of contact between the transmission rotating body and the transmission strip. Both ends of the transmission strip are connected to the pair of transmission connectors, The drive source is connected to the main body, The wheel steering device is characterized in that the control unit is configured to control the rotation of the transmission rotating body by the drive source.

2. The aforementioned transmission strip is composed of a chain, The wheel steering device according to claim 1, characterized in that the transmission rotating body is composed of a sprocket.

3. The steering mechanism is provided with a tensioner that presses against the transmission strip, The wheel steering device according to claim 1, characterized in that the tensioner is connected to the main body.

4. The wheel steering device according to claim 3, characterized in that the tensioner and the drive source are fixed to the main body via an interlocking fixing member.

5. The main body is pivotably connected to the vehicle body via a pivot shaft. The wheel steering device according to claim 1, characterized in that the steering transmission member is connected to the vehicle body via a buffer member.

6. The wheel steering device according to claim 1, characterized in that the control unit is configured to control the rotation of the transmission rotating body by the drive source based on an operation signal from the vehicle body's operating unit.

7. The wheels are provided in pairs on the left and right sides of the vehicle body. The steering unit is provided one for each of the multiple wheels to be steered. The wheel steering device according to claim 1, characterized in that the control unit is configured to control a plurality of steering units simultaneously.

8. The steering unit further includes a detection unit capable of detecting the steering angle of the steering transmission member, The wheel steering device according to claim 1, characterized in that the control unit is configured to control the rotation of the transmission rotating body by the drive source based on the steering angle information of the steering transmission member detected by the detection unit.

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