Wheel steering device

Abstract

The present invention provides a wheel steering device whereby, with a simple configuration, manufacturing cost and weight can be kept from increasing, a reduction in available installation space within a vehicle body can be suppressed, and the direction of a wheel can be adjusted easily. Provided is a wheel steering device (100) having a steering unit (110) and a control part. The steering unit (110) has a main body part (111), a steering transmission member (112) that rotatably connects a wheel (T1) and the main body part (111), and a steering mechanism (113). The steering mechanism (113) has a transmission strip body (114), a transmission rotating body (115) that comes into contact with the transmission strip body (114) and performs an advance / retreat operation, and a drive source (116) that connects to the transmission rotating body (115) in a manner allowing for forward and reverse rotation. The steering transmission member (112) is provided with a pair of transmission connecting parts (120), and the two ends of the transmission strip body (114) are connected to the pair of transmission connecting parts (120), respectively. The drive source (116) is connected to the main body part (111), and the control part is configured to control the rotation of the transmission rotating body (115).

Description

Wheel steering device

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

[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 in this Patent Document 1 drives the actuator 7 based on an output signal obtained by reading the operation of the steering wheel 2 of the steering device 3 with a sensor, and meshes with a pinion that rotates by the actuator 7. By moving the rack gear to the 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, enabling steering.

[0004] Japanese Unexamined Patent Application Publication No. 2023 - 104296

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

[0006] That is, in the wheel steering devices known in Patent Document 1 and the like, since the left and right steering wheels are interlocked and their directions are changed by the movement of the rack gear connected via tie rods, when there are problems such as imbalance in the directions of the left and right steering wheels, there is a risk that it will be difficult to easily adjust the directions of the left and right steering wheels. Also, since it is necessary to arrange a rack gear between the left and right steering wheels so as to cross the vehicle body, the space for installing the steering device becomes large, and there is a risk that the constraints become severe when securing space for arranging components other than the steering device. In particular, when suspensions are connected to each of the left and right steering wheels to mitigate impacts during running, thereby individually mitigating the impacts on each of the left and right steering wheels, there is a risk that the structure of the configuration itself connecting the left and right steering wheels becomes complicated, resulting in an increase in cost and weight, and a risk that the layout with peripheral components inside the vehicle including the wheel steering device becomes complicated.

[0007] Furthermore, there was a risk that the manufacturing cost would increase due to the larger size of the components that make up the steering mechanism, as well as an increase in weight.

[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.

[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.

[0010] The wheel steering device according to claim 1 comprises a steering mechanism comprising 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 a transmission rotation axis 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 axis 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 axis, 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 only necessary 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 within the vehicle body, and preventing complexity in the device configuration and layout with surrounding components within the vehicle body. In addition, since it does not require large components that cross the vehicle body between the pair of wheels, the steering unit can be constructed inexpensively. Moreover, since the steering transmission member is steered along with the wheel by moving the transmission string forward and backward, the configuration of the steering unit itself does not move significantly, allowing for a more compact and simpler design compared to configurations where the left and right steering wheels are connected via tie rods, etc.

[0011] According to the configuration described in claim 2, the transmission strip is made of a chain and the transmission rotating body is made of a sprocket, so 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. In addition, even when the chain or sprocket wears out, the steering of the wheels can be easily stabilized without the need for major adjustments by replacing it with a chain and sprocket of the same specifications. According to the configuration described in claim 3, the steering mechanism is provided with a tensioner that presses against the transmission strip, and the tensioner is connected to the main body, so even when the transmission strip made of a chain stretches slightly and slack occurs, the tensioner can always apply tension to the transmission strip by pressing against it, and backlash can be prevented.

[0012] According to the configuration described in claim 4, since the tensioner and drive source are fixed to the main body via an interlocking fixing member, the tensioner and 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 deviation in the positional relationship between the tensioner and the drive source can be kept to a minimum. According to the configuration described in claim 5, since 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 buffer member, even if there is a step in the road or an obstacle that can be overcome, the wheels can pivot around the pivot shaft together with the steering unit, and the buffer member can reduce the momentum during the pivot, 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 vehicle body on the left and right sides, 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 a pair of left and right steering units in conjunction, and the steering angle of one of the left and right wheels can be easily adjusted individually without affecting the other wheel in 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.

[0015] A schematic top view showing a vehicle P equipped with a wheel steering device 100 according to one embodiment of the present invention. A top view of the wheel steering device 100 according to one embodiment of the present invention. A front view of the wheel steering device 100 according to one embodiment of the present invention. A side cross-sectional view of the wheel steering device 100 according to one embodiment of the present invention. A top view showing the state in which the front wheels T1 are steered by the wheel steering device 100 according to one embodiment of the present invention.

[0016] A wheel steering device 100 according to one embodiment of the present invention will be described below with reference to the drawings. For the sake of explanation, the control unit will not be shown.

[0017] As shown in Figures 1 to 4, the wheel steering device 100 according to one embodiment of the present invention is mounted between the front wheel T1, which is a wheel of the vehicle P, and the vehicle body F. A similar configuration to the wheel steering device 100 is also mounted between the front wheel T2 and the vehicle body F on the front wheel T2 side, and the front wheels T1 and T2 are configured to be steered in conjunction by a common control unit. The rear wheels T3 and T4 are mounted to the vehicle body F so as to be rotatable around the central axis of the rear wheels T3 and T4, without the same configuration as the wheel steering device 100.

[0018] A wheel steering device 100 according to one 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 includes a main body 111 connected to the vehicle body F, a steering transmission member 112 that connects the front wheel T1 and the main body 111 so as to be rotatable relative to each other by 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. The pressing part 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 connecting section 112c is rotatably connected to the front wheel T1 via a 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 rotation 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 section 111 with the steering shaft 123 as the axis of rotation. Between the main body section 111 and the lower section 112b, there is a steering angle detection unit S capable of detecting the actual steering angle of the steering transmission member 112, 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, and minimizes the positional misalignment between the tensioner 117 and the drive source 116.

[0023] Next, a method for steering the front wheels T1 using a wheel steering device 100 according to one embodiment of the present invention will be described with reference to Figures 1 to 5. In this invention, 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 operation unit (not shown) to a control unit by the driver operating a steering wheel unit (not shown).

[0024] First, the driver, seated 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, which changes according to the amount of operation of the steering unit (not shown) by the driver. The control unit then 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, sending the transmission strip 114, which 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, and 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 the operation of the steering wheel unit (not shown) and the front wheels T1 beginning to turn towards the target steering angle via the operation unit (not shown) and the 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 front wheel T2 in conjunction with the operation of the steering unit (not shown). In addition, if the control unit is configured to detect information on road surface conditions, vehicle speed, acceleration / deceleration, and cornering conditions, the steering angles of the front wheel T1 and front wheel 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, so the optimal direction of the front wheel T1 and front wheel T2 can be automatically selected 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 the steering wheel unit (not shown) to change the direction of the vehicle. Furthermore, since one wheel steering device is provided for each of the front wheels T1 and T2 which are arranged side by side, 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 that connect the front wheels T1 and T2 to transmit power, so that the space inside the vehicle body F is not greatly occupied.

[0029] Furthermore, since it does not require the use of large components that connect the front wheel T1 to the front wheel T2 to transmit power, the manufacturing cost of the wheel steering device itself can be kept low, and the weight can be reduced, thus improving the fuel efficiency of the vehicle. In addition, since the steering transmission member 112 is steered together with the front wheel T1 by moving the transmission strip 114, which has both ends connected to transmission connection parts 120 (first transmission connection part 120a, second transmission connection part 120b), the steering unit 110 itself does not move significantly, and it 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 strip 114 is made up of a chain and the transmission rotating body 115 is made up of a sprocket, the error in the steering angle of the front wheel T1 relative 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 sprocket, allowing for stable steering to be maintained for a long period of time. In addition, even when the transmission strip 114 or transmission rotating 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 made up of a chain, even if the transmission string 114 stretches slightly, tension is always applied to the transmission string 114, thus preventing backlash. In addition, the main body 111 is pivotably connected to the vehicle body F via the pivot shaft 118, and the steering transmission member 112 is connected to the vehicle body F via the cushioning member 121. Therefore, 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 cushioning member 121 reduces the momentum during the pivoting, thus maintaining stable driving. Moreover, since the steering unit 110 pivots in conjunction with the main body 111, the steering unit 110 can perform its steering function even when pivoting, further maintaining 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 explained that wheel steering devices are 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, in the embodiments described above, the transmission strip was described as being composed of a chain and the transmission rotating body as a sprocket. However, the configuration of the transmission strip and the transmission rotating body are not limited to these. 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 using frictional force on the belt-composed transmission strip.

[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.

[0035] 100 ... Wheel steering device 110 ... Steering unit 111 ... Main body 112 ... Steering transmission member 112a ... Upper part 112b ... Lower part 112c ... Intermediate connection part 113 ... Steering mechanism 114 ... Transmission strip 115 ... Transmission rotating body 116 ... Drive source 116a ... Transmission rotating shaft 117 ... Tensioner 117a ... Pressing part 118 ... Oscillating shaft 119 ... Connecting shaft 120 ... Transmission connection part 120a ... First transmission connection part 120b ... Second transmission connection part 121 ... Cushioning member 122 ... Interlocking fixing member 123 ... Steering shaft F ... Vehicle body P ... Running vehicle T1, T2 ... Front wheels T3, T4 ... Rear wheels S ... Steering angle detection unit

Claims

1. A wheel steering device comprising a steering unit and a control unit, which are provided between a vehicle body and a wheel for steering the wheel, wherein the steering unit comprises a main body connected to the vehicle body, a steering transmission member that connects 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, 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.

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

3. The wheel steering device according to claim 1, characterized in that the steering mechanism is provided with a tensioner that presses against the transmission strip, and 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 wheel steering device according to claim 1, characterized in that 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 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 wheel steering device according to claim 1, characterized in that 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 the multiple steering units simultaneously.

8. The wheel steering device according to claim 1, wherein the steering unit further comprises 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.

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