Four-wheel independent steering mechanism driven by double-helix swing oil cylinder and used for commercial vehicle

Abstract

A four-wheel independent steering mechanism driven by a double-helix swing oil cylinder and used for a commercial vehicle comprises a suspension module, the top end of the suspension module is connected with a vehicle frame, the lower end of the suspension module is connected with a damping module, the double-helix swing oil cylinder is installed below the damping module, and the damping module is connected with vehicle tires through a right tire main shaft. The integration of a suspension, a damping module and a steering module is realized; the double-helix swing oil cylinder is an ideal power source of a low-speed, large-torque and large-angle swing mechanism, can output 1100 Nm steering torque and 180 deg steering angle, and meets the steering requirement of the large-load working condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of independent steering for commercial vehicles, and particularly relates to a four-wheel independent steering mechanism for commercial vehicles driven by a double-helix swing oil cylinder. Background Art

[0002] Currently, automotive steering systems mainly include mechanical steering systems, power steering systems, and steer-by-wire systems (Steering by Wire, hereinafter referred to as SBW), etc. Among them, the steer-by-wire system mainly includes forms such as front-wheel steer-by-wire, rear-wheel steer-by-wire, and four-wheel independent steer-by-wire.

[0003] The steer-by-wire cancels the mechanical connection between the steering wheel and the steering actuator, and completely connects the steering control unit and the steering actuator by electrical control signals. Compared with traditional steering mechanisms such as mechanical and power steering, the SBW system has the advantages of compact structure, flexible layout, lightweight, and fast response speed. In the Active Four-wheel Steering (AFS) system, the steering torques of the four wheels of the vehicle are independently controlled by a single power source respectively. This steering scheme can greatly improve the passability of commercial vehicles under special road conditions and provide a reliable actuator for the precise torque control scheme based on autonomous driving.

[0004] Currently, the active four-wheel independent steering mechanisms put into use mainly include improved types of steer-by-wire systems, independent steering systems, and traditional electric power steering systems. These steering mechanisms usually equip each wheel with an independent steering actuator on the premise of adapting to the hub motor layout. These actuators are usually motors, and the control unit controls the motor drive through electrical signals to achieve wheel steering. The torque ranges of the actuators of the existing steer-by-wire four-wheel independent steering systems vary depending on the vehicle type. For common passenger cars, front-wheel steering usually uses a permanent magnet synchronous motor with a reduction mechanism. The motor directly outputs 5 - 15 N·m, and after being reduced by 10:1 to 20:1, the torque at the wheel end reaches 80 - 300 N·m; for rear-wheel steering, due to space limitations, the motor outputs 3 - 10 N·m, and after amplification, it is 50 - 200 N·m. Commercial vehicles and special vehicles have higher requirements. For example, the ZF ReAX system of ZF Group uses a 30 - 50 N·m motor combined with hydraulic pressure or a high reduction ratio (above 20:1) to achieve a torque output of more than 1000 N·m at the wheel end. Prototype vehicles such as Toyota bZ4X use a steer-by-wire actuator without mechanical backup, which can output a torque of 250 N·m. Generally speaking, the motor actuators of the existing active four-wheel independent steering systems have a relatively small output torque. To output a large torque, a reducer with a large reduction ratio needs to be matched, and the volume of such a reducer is also relatively large.

[0005] The existing four-wheel independent steering system can achieve a differentiated steering angle range for the front and rear wheels to meet the needs of flexible control or low-speed maneuverability. The International Society of Automotive Engineers' technical documents on steering systems point out that in the field of passenger cars, the front wheel steering angle is usually ±30°-50° (such as traditional fuel vehicles), and the wire control system can be further optimized; the rear wheel steering angle is smaller, generally between ±3°-15°, for example, the maximum rear wheel steering published in the white paper of the Mercedes-Benz EQS technology conference is ±10°, which improves high-speed stability, and the Tesla Cybertruck rear wheel industry speculates that it can reach ±10°. Commercial vehicles and special vehicles have larger angles, such as the Rivian R1T's rear wheels can reversely deflect ±12 in the "tank steering" mode to enhance the flexibility of urban autonomous driving. In terms of scientific research prototypes, the Toyota bZ4X wire-controlled prototype has a front wheel steering of ±50° and a rear wheel of ±8°; the Apollo IE supercar uses four-wheel active steering, with a rear wheel of ±7° to optimize track cornering. The future trend is to have a larger rear wheel angle (±20° or more), such as Hyundai Mobis' driverless concept car with a rear wheel steering of ±25°, combined with the front wheel ±45° to achieve a very small turning radius. In general, the existing four-wheel independent steering system still has a small independent steering angle for the front and rear wheels, and commercial vehicles and concept designs need to explore a wider range.

[0006] In summary, the following deficiencies exist: 1) The existing independent steering mechanism uses an electric motor as a power source. The electric motor is highly dependent on batteries, has high costs, and low reliability. The torque provided is relatively small and cannot meet the torque requirements of more than 1000N·m required by commercial vehicles. At the same time, the motor needs to be used with a reducer, which makes it large in size and difficult to use for large vehicles. In addition, the cost is high. 2) The steering angle of a single tire of the existing independent steering mechanism is generally small, and the applicable working conditions are limited. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a four-wheel independent steering mechanism for commercial vehicles driven by a double-helix swing cylinder. The double-helix swing cylinder is an ideal power source for low-speed, high-torque, and large-angle swing mechanisms. It can output 1100Nm steering torque and 180deg steering angle to meet the steering requirements of large load conditions.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A four-wheel independent steering mechanism for commercial vehicles driven by a double-helix swing cylinder comprises a suspension module I, the top of which is connected to a vehicle frame, the bottom of which is connected to a damping module II, a double-helix swing cylinder III is installed below the damping module II, and the damping module II is connected to a vehicle tire via a right tire spindle IV, thereby realizing the integration of the suspension, damping and steering modules.

[0010] The suspension module I includes a first damping shaft 1 and a second damping shaft 37. The upper ends of the first damping shaft 1 and the second damping shaft 37 are connected to a frame connecting member 4, and the frame connecting member 4 is connected to the frame and moves synchronously with the spring suspension. The middle parts of the first damping shaft 1 and the second damping shaft 37 are connected by a first sliding bearing 6, a second sliding bearing 36 and an upper fixing joint 7. A first spring 5 is arranged outside the first damping shaft 1. The first spring 5 is concentrically installed with the first damping shaft 1 and is limited between the frame connecting plate 4 and the upper fixing joint 7. A second spring 38 is arranged outside the second damping shaft 37. The second spring 38 is concentrically installed with the second damping shaft 37 and is limited between the frame connecting plate 4 and the upper fixing joint 7.

[0011] The damping module II is divided into a left chamber and a right chamber. The left chamber includes a damping cylinder 10. The damping cylinder 10 is concentrically installed with the first damping shaft 1 between the upper fixing joint 7 and the lower fixing joint 13. The lower end of the first damping shaft 1 is connected to the lower fixing joint 13 through a third sliding bearing 14. A number of first square head flat end set screws 11 are installed on a part of the surface of the first damping shaft 1 inside the damping cylinder 10. The cavity of the damping cylinder 10 is filled with damping grease and damping particles.

[0012] The right chamber includes a steering member 30. The steering member 30 is fixed on the upper fixing joint 7. The steering member 30 is concentrically installed at the lower end of the second damping shaft 37. The upper end of the steering member 30 is connected to the second damping shaft 37 through a fourth sliding bearing 35. A number of second square head flat end set screws 34 are installed on the end surface of the lower end of the second damping shaft 37 inside the steering member 30. The cavity of the steering member 30 is filled with damping grease and damping particles.

[0013] A middle fixing joint 15 is installed between the damping cylinder 10 and the steering member 30. The middle fixing joint 15 is fixed between the upper fixing joint 7 and the lower fixing joint 13. A support plate 8 is installed on the left side of the damping module II. The support plate 8 is fixed on the upper fixing joint 7 and the lower fixing joint 13.

[0014] The double - helix swing oil cylinder III includes an oil cylinder shaft 21. The upper end of the oil cylinder shaft 21 is connected to the lower end of the steering member 30. The oil cylinder shaft 21 is connected to the lower fixing joint 13 through a fifth sliding bearing 29. The oil cylinder shaft 21 below the lower fixing joint 13 is connected to an oil cylinder end cover 16, and the oil cylinder end cover 16 is fixed on the lower fixing joint 13. The upper end of the oil cylinder body 17 outside the oil cylinder shaft 21 is fixedly connected to the oil cylinder end cover 16. A first thrust bearing 18 and a second thrust bearing 19 are installed between the middle boss of the oil cylinder shaft 21, the oil cylinder end cover 16 and a spacer 20. The spacer 20 is fixed on the inner wall of the oil cylinder body 17 through an elastic key 25. The external thread at the lower end of the oil cylinder shaft 21 is matched with the internal thread of a secondary spiral pair 22, and the external thread of the secondary spiral pair 22 is matched with the internal thread at the bottom of the oil cylinder body 17. By injecting oil through the upper and lower oil injection ports to push the secondary spiral pair 22 to move up and down while rotating forward and backward, the oil cylinder shaft 21 is driven to rotate to achieve steering.

[0015] An angle sensor 23 is installed at the bottom of the oil cylinder block 17 to detect and feedback the steering angle of the secondary helical pair 22, and the steering angle reaches -90° to +90°.

[0016] The tire main shaft Ⅳ and the steering member 30 are connected by a lock ring outer race angular contact ball bearing 33 to transmit the steering force to the vehicle tire.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention uses a double - helix swing oil cylinder as the power source, so it has the advantages of compact structure, large output torque, large output rotation angle, high positioning accuracy, high efficiency, low cost, and strong stability. It can be applied to commercial vehicles with large loads. When the output torque can reach 1100 N·m, compared with the electric actuator, the space occupied by the speed reducer is saved. And commercial vehicles usually have a hydraulic system. The present invention uses an oil cylinder as the power source, which can be matched with the hydraulic system of commercial vehicles, further saving space.

[0019] (2) The present invention uses a double - helix swing oil cylinder to output the steering angle, which can greatly expand the steering angle. Therefore, the rotation angle range of a single tire of the present invention is -90° to +90°, and it can adapt to more working conditions such as crab driving, diagonal driving, short U - turn, and in - place turning. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of an embodiment of the present invention.

[0021] Figure 2 is a sectional view of an embodiment of the present invention.

[0022] Figure 3 is a schematic structural diagram of the suspension module Ⅰ of an embodiment of the present invention.

[0023] Figure 4 is a schematic structural diagram of the damping module Ⅱ of an embodiment of the present invention.

[0024] Figure 5 is a schematic structural diagram of the double - helix swing oil cylinder Ⅲ of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following further describes the present invention in detail with reference to the embodiments and the drawings.

[0026] Refer to Figure 1, A four-wheel independent steering mechanism for commercial vehicles driven by a double-helical swing cylinder, including suspension module I. The top of suspension module I is connected to the vehicle frame, and the lower end of suspension module I is connected to damping module II. A double-helical swing cylinder III is installed below damping module II. Damping module II is connected to the vehicle tire through the right tire main shaft IV, realizing the integration of modules such as suspension, damping, and steering.

[0027] Refer to Figure 2 、 Figure 3 , The suspension module I includes a first damping shaft 1 and a second damping shaft 37. The upper ends of the first damping shaft 1 and the second damping shaft 37 are connected to the vehicle frame connecting piece 4, and the vehicle frame connecting piece 4 is connected to the vehicle frame. The upper end of the first damping shaft 1 is limited and fixed on the vehicle frame connecting piece 4 by the first hexagon nut 2 and the second hexagon nut 3. The upper end of the second damping shaft 37 is limited and fixed on the vehicle frame connecting piece 4 by the third hexagon nut 39 and the fourth hexagon nut 40; The middle parts of the first damping shaft 1 and the second damping shaft 37 are connected by the first sliding bearing 6, the second sliding bearing 36 and the upper fixing section 7; A first spring 5 is arranged outside the first damping shaft 1. The first spring 5 is concentrically installed with the first damping shaft 1 and limited between the vehicle frame connecting plate 4 and the upper fixing section 7. A second spring 38 is arranged outside the second damping shaft 37. The second spring 38 is concentrically installed with the second damping shaft 37 and limited between the vehicle frame connecting plate 4 and the upper fixing section 7; The combination of the first spring 5 and the second spring 38 can increase the spring stiffness and improve the stability and controllability of the vehicle. The first damping shaft 1 and the second damping shaft 37 are fixedly connected to the vehicle chassis in a threaded connection form and move synchronously with the spring suspension.

[0028] Refer to Figure 2 、 Figure 4 , The damping module II is divided into a left chamber and a right chamber; The left chamber includes a damping cylinder 10. The damping cylinder 10 is concentrically installed with the first damping shaft 1 between the upper fixing section 7 and the lower fixing section 13. The lower end of the first damping shaft 1 is connected to the lower fixing section 13 through the third sliding bearing 14. And there are two identical O-ring seals 12 for sealing between the damping cylinder 10 and the upper fixing section 7 and the lower fixing section 13. 56 first square head flat end set screws 11 are evenly installed on a part of the surface of the first damping shaft 1 in the damping cylinder 10 in the way of 7 circles × 8 pieces. The cavity of the damping cylinder 10 is filled with damping grease and damping particles;

[0029] The right chamber includes a steering part 30. The steering part 30 is fixed on the upper fixing section 7. The steering part 30 is concentrically installed at the lower end of the second damping shaft 37. The upper end of the steering part 30 is connected to the second damping shaft 37 through the fourth sliding bearing 35. 24 second square head flat end set screws 34 are evenly installed on the end surface of the lower end of the second damping shaft 37 in the steering part 30 in the way of 3 circles × 8 pieces. The cavity of the steering part 30 is filled with damping grease and damping particles;

[0030] A middle fixing section 15 is installed between the damping cylinder 10 and the steering member 30. The middle fixing section 15 is fixed between the upper fixing section 7 and the lower fixing section 13. A support plate 8 is installed on the left side of the damping module II. It is fixed to the upper fixing section 7 and the lower fixing section 13 by 8 screws identical to the inner hexagon socket head cap screws 9, and plays a supporting role at the same time.

[0031] Referring to Figure 2 , Figure 5 , the described double - helix oscillating oil cylinder III includes an oil cylinder shaft 21. The upper end of the oil cylinder shaft 21 is connected to the lower end of the steering member 30 through a first key 31 and a second key 32. The output torque of the oil cylinder shaft 21 drives the steering member 30 to rotate. The oil cylinder shaft 21 is connected to the lower fixing section 13 through a fifth sliding bearing 29. A sealing ring 27 and a dust - proof ring 28 are installed between the oil cylinder shaft 21 below the lower fixing section 13 and the oil cylinder end cover 16. The oil cylinder end cover 16 is fixed to the lower fixing section 13 by bolts; the upper end of the oil cylinder body 17 outside the oil cylinder shaft 21 is fixedly connected to the oil cylinder end cover 16, and a sealing ring 26 is installed between them; a first thrust bearing 18 and a second thrust bearing 19 are installed between the boss in the middle section of the oil cylinder shaft 21, the oil cylinder end cover 16 and the spacer ring 20 to limit the position while ensuring the smooth rotation of the oil cylinder shaft 21. The spacer ring 20 is fixed to the inner wall of the oil cylinder body 17 by an elastic snap key 25; the external thread at the lower end of the oil cylinder shaft 21 is matched with the internal thread of the secondary screw pair 22, and the external thread of the secondary screw pair 22 is matched with the internal thread at the bottom of the oil cylinder body 17. A sealing ring 24 is installed between the secondary screw pair 22 and the oil cylinder body 17; by injecting oil through the upper and lower oil injection ports to push the secondary screw pair 22 to move up and down while rotating forward and backward, the oil cylinder shaft 21 is driven to rotate to achieve steering.

[0032] An angle sensor 23 is installed at the bottom of the oil cylinder body 17 to detect and feedback the steering angle of the secondary screw pair 22, and the steering angle reaches - 90° to + 90°.

[0033] Referring to Figure 4 , the described tire main shaft IV is connected to the right side of the steering member 30 through a lock - ring outer - ring angular contact ball bearing 33 to transmit the steering force to the vehicle tire.

[0034] The working principle of the present invention is as follows:

[0035] As a mechanism for four - wheel independent steering of an automobile, the top of the suspension module I is connected to the vehicle frame through a vehicle - frame connecting member 4. The suspension module I and the damping module II together realize the functions of shock absorption and comfort improvement of the automobile. The oil cylinder shaft 21 of the double - helix oscillating oil cylinder III and the damping shaft 38 of the damping module II are connected by a key to provide power output to drive the steering member to steer, thereby driving the tire to steer; the entire system is connected to the vehicle tire through the right - hand tire main shaft IV, realizing the integration of modules such as suspension, damping, and steering.

[0036] The principle of the suspension module I and the damping module II to jointly achieve the functions of shock absorption and comfort improvement of the vehicle is that when the vehicle is impacted by road unevenness, the first spring 5 and the second spring 38 in the suspension module I deform rapidly, driving the first damping shaft 1 and the second damping shaft 37 to move up and down. At this time, 80 screws installed on the two damping shafts and consistent with the first square head flat end set screw 11 and the second square head flat end set screw 34 generate frictional damping and radiation damping with the mixture of damping grease and damping particles in the damping chamber formed by the damping cylinder 10 and the steering part 30 in the damping module II, hindering the rapid movement of the damping shaft and thus hindering the rapid deformation of the suspension spring, achieving the effects of reducing the resonance amplitude of the chassis of pure electric commercial vehicles, reducing the noise of pure electric commercial vehicles, and quickly restoring the stable state of the suspension after instantaneous impact, so as to improve the comfort and smoothness of the vehicle.

[0037] The double - helix swing oil cylinder III is the power source of the steering module. The oil cylinder shaft 21 directly transmits the output torque, output rotation angle, etc. to the steering part 30, so that the wheel rotates around the output shaft of the swing oil cylinder. The external thread of the secondary helix pair 22 is matched with the internal thread at the bottom of the oil cylinder body 17, so that while injecting oil through the upper and lower oil injection ports to push the secondary helix pair 22 to move up and down, it also performs forward and reverse rotation movements; the external thread at the lower end of the oil cylinder shaft 21 is matched with the internal thread of the secondary helix pair 22, so that when the secondary helix pair 22 moves up and down and rotates, it drives the oil cylinder shaft 21 to rotate forward and reverse, thus realizing the output of the rotational torque of the oil cylinder shaft 21, changing the direction of the tire main shaft IV through the rotation of the steering part 30, and realizing wheel steering. The angle sensor 23 is used to measure the rotation angle output by the oil cylinder shaft 21 to realize real - time monitoring of the steering angle of the wheels of pure electric commercial vehicles.

Claims

1. A four-wheel independent steering mechanism for commercial vehicles driven by a double-helical oscillating oil cylinder, characterized in that: It includes a suspension module (Ⅰ), the top of the suspension module (Ⅰ) is connected to the vehicle frame, the lower end of the suspension module (Ⅰ) is connected to a damping module (Ⅱ), a double-helical swing oil cylinder (Ⅲ) is installed below the damping module (Ⅱ), and the damping module (Ⅱ) is connected to an automotive tire through a right-side tire main shaft (Ⅳ), realizing the integration of the suspension, damping, and steering modules.

2. The four-wheel independent steering mechanism for commercial vehicles according to claim 1, wherein: The suspension module (Ⅰ) includes a first damping shaft (1) and a second damping shaft (37). The upper ends of the first damping shaft (1) and the second damping shaft (37) are connected to a vehicle frame connecting member (4), and the vehicle frame connecting member (4) is connected to the vehicle frame and moves synchronously with the spring suspension. The middle parts of the first damping shaft (1) and the second damping shaft (37) are connected through a first sliding bearing (6), a second sliding bearing (36), and an upper fixed joint (7). A first spring (5) is provided outside the first damping shaft (1), and the first spring (5) is concentrically installed with the first damping shaft (1) and limited between the vehicle frame connecting plate (4) and the upper fixed joint (7). A second spring (38) is provided outside the second damping shaft (37), and the second spring (38) is concentrically installed with the second damping shaft (37) and limited between the vehicle frame connecting plate (4) and the upper fixed joint (7).

3. The four-wheel independent steering mechanism for commercial vehicles according to claim 2, characterized in that: The damping module (Ⅱ) is divided into a left chamber and a right chamber. The left chamber includes a damping cylinder (10), and the damping cylinder (10) is concentrically installed with the first damping shaft (1) between the upper fixed joint (7) and the lower fixed joint (13). The lower end of the first damping shaft (1) is connected to the lower fixed joint (13) through a third sliding bearing (14). A part of the surface of the first damping shaft (1) inside the damping cylinder (10) is installed with several first square head flat end set screws (11), and the cavity of the damping cylinder (10) is filled with damping grease and damping particles. The right chamber includes a steering member (30), and the steering member (30) is fixed on the upper fixed joint (7). The steering member (30) is concentrically installed at the lower end of the second damping shaft (37). The upper end of the steering member (30) is connected to the second damping shaft (37) through a fourth sliding bearing (35). A part of the end surface of the lower end of the second damping shaft (37) inside the steering member (30) is installed with several second square head flat end set screws (34), and the cavity of the steering member (30) is filled with damping grease and damping particles.

4. The four-wheel independent steering mechanism for commercial vehicles according to claim 3, characterized in that: A middle fixed joint (15) is installed between the damping cylinder (10) and the steering member (30), and the middle fixed joint (15) is fixed between the upper fixed joint (7) and the lower fixed joint (13). A support plate (8) is installed on the left side of the damping module (Ⅱ), and the support plate (8) is fixed on the upper fixed joint (7) and the lower fixed joint (13).

5. The four-wheel independent steering mechanism for commercial vehicles according to claim 3, characterized in that: The tire main shaft (Ⅳ) is connected to the steering member (30) through a lock ring outer race angular contact ball bearing (33) to transmit the steering force to the automotive tire.

6. The four-wheel independent steering mechanism for commercial vehicles according to claim 3, wherein: The described double-helix oscillating oil cylinder (Ⅲ) includes an oil cylinder shaft (21). The upper end of the oil cylinder shaft (21) is connected to the lower end of the steering member (30). The oil cylinder shaft (21) is connected to the lower fixed section (13) through a fifth sliding bearing (29). The oil cylinder shaft (21) below the lower fixed section (13) is connected to the oil cylinder end cover (16), and the oil cylinder end cover (16) is fixed on the lower fixed section (13). The upper end of the oil cylinder body (17) outside the oil cylinder shaft (21) is fixedly connected to the oil cylinder end cover (16). A first thrust bearing (18) and a second thrust bearing (19) are installed between the middle-stage boss of the oil cylinder shaft (21), the oil cylinder end cover (16), and the spacer ring (20). The spacer ring (20) is fixed to the inner wall of the oil cylinder body (17). The external thread at the lower end of the oil cylinder shaft (21) is in mutual cooperation with the internal thread of the secondary screw pair (22), and the external thread of the secondary screw pair (22) is in mutual cooperation with the internal thread at the bottom of the oil cylinder body (17). By injecting oil through the upper and lower oil injection ports to push the secondary screw pair (22) to move up and down while rotating forward and backward, the oil cylinder shaft (21) is driven to rotate to achieve steering.

7. The four-wheel independent steering mechanism for commercial vehicles according to claim 6, characterized in that: An angle sensor (23) is installed at the bottom of the oil cylinder body (17) to detect and feedback the steering angle of the secondary screw pair (22), and the steering angle reaches -90° to +90°.

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