Electric steering system and method and crane

Abstract

The invention discloses an electric steering system and method and a crane in the technical field of engineering machinery, and aims to solve the problems that in the prior art, mechanical steering and hydraulic power assisting modes are mostly adopted, large vibration exists, abnormal sound and noise are likely to be generated, oil of a hydraulic system is likely to be polluted, and the power assisting effect of the power assisting system is affected. The system comprises a front steering system and a rear steering system, the front steering system comprises a steering wheel and a front axle, the steering wheel is movably connected with an electric steering gear through a steering column, the electric steering gear is movably connected with a steering plumbing arm, and the front axle is rotationally connected with a first wheel set and a first electric cylinder; pure electric power assistance is adopted, the problem that a hydraulic system is difficult to avoid is solved, vibration during vehicle steering is reduced, abnormal sound and noise are not likely to be generated, hydraulic oil is prevented from being used, hydraulic parts are prevented from being damaged, and the intelligent vehicle steering system better conforms to the development trend of intelligent vehicles.

Description

Technical Field

[0001] The present invention relates to an electric steering system, method and crane, belonging to the technical field of construction machinery. Background Art

[0002] The steering system is one of the most important systems of modern construction machinery vehicles. It is an important hub connecting people and vehicles and provides necessary conditions for the safe driving of vehicles. Due to the heavy axle load of the steering axle of the crane, the electric steering gear cannot provide enough assist torque, so mechanical steering and hydraulic assist forms are mostly adopted. With the development of vehicle electrification, there are more intelligent requirements for the steering system. Applying electric steering technology to heavy-duty vehicles, such as truck cranes, has also become a current research hotspot.

[0003] Existing crane steering systems mostly adopt mechanical steering and hydraulic assist forms, which have large vibrations, are prone to generate abnormal noises and noises, and the oil quality of the hydraulic system is easily polluted, affecting the assist effect of the assist system or damaging hydraulic components, thus affecting the use effect of the steering system. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an electric steering system, method and crane to solve the problems that existing crane steering systems mostly adopt mechanical steering and hydraulic assist forms, have large vibrations, are prone to generate abnormal noises and noises, and the oil quality of the hydraulic system is easily polluted, affecting the assist effect of the assist system or damaging hydraulic components.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides an electric steering system, including a front steering system and a rear steering system. The front steering system includes a steering wheel and a front axle. The steering wheel is movably connected to an electric steering gear through a steering column. A steering pitman arm is movably connected to the electric steering gear. A first wheel set and a first electric cylinder are rotatably connected to the front axle. The steering pitman arm is movably connected to the first wheel set through a steering tie rod. The output end of the first electric cylinder is rotatably connected to the first wheel set; The rear steering mechanism includes a second electric cylinder and a rear axle. A second wheel set and the second electric cylinder are rotatably connected to the rear axle. The output end of the second electric cylinder is rotatably connected to the second wheel set.

[0006] Further, the steering pitman arm is movably connected to the first wheel set through a pushing mechanism. The pushing mechanism includes a rocker arm rotatably arranged inside the vehicle frame. A first push rod is rotatably connected between the rocker arm and the steering pitman arm. A second push rod is rotatably connected between the rocker arm and the first wheel set. The first electric cylinder is rotatably arranged on the inner wall of the vehicle frame. The output end of the first electric cylinder is rotatably connected to the rocker arm.

[0007] Further, the front steering system further includes a vehicle steering controller, which is electrically connected to an electric steering gear controller, a first electric cylinder controller, and a first angle sensor. The electric steering gear controller is electrically connected to the electric steering gear, the first electric cylinder controller is electrically connected to the first electric cylinder, and the first angle sensor is installed on the first wheel set.

[0008] Further, the rear steering system further includes a second electric cylinder controller and a second angle sensor. The second electric cylinder controller is electrically connected to the second electric cylinder, the second angle sensor is installed on the second wheel set, and both the second electric cylinder controller and the second angle sensor are electrically connected to the vehicle steering controller.

[0009] In a second aspect, the present invention provides an electric steering method, based on the electric steering system described in the first aspect, including the working method of the front steering system and the working method of the rear steering system. The working method of the front steering system includes the following steps: The driver drives the steering wheel to turn, and inputs the steering torque to the electric steering gear. The electric steering gear obtains a torque signal according to the steering torque, and transmits the torque signal to the vehicle steering controller and the electric steering gear controller. The vehicle steering controller calculates the first electric cylinder assist torque according to the torque signal and controls the first electric cylinder to work. The electric steering gear controller calculates the electric steering gear assist torque according to the torque signal and controls the electric steering gear to work. The driver adjusts the steering torque so that the sum of the first electric cylinder assist torque and the electric steering gear assist torque is greater than the resistance torque of the first wheel set to drive the first wheel set to turn. The first angle sensor obtains the rotation angle of the first wheel set. When the rotation angle of the first wheel set is equal to the preset angle, the steering operation of the front steering system ends.

[0010] Further, the working method of the rear steering system specifically includes: The first angle sensor transmits the rotation angle of the first wheel set to the vehicle steering controller. The vehicle steering controller calculates the theoretical rotation angle of the second wheel set according to the preset steering mode and the rotation angle of the first wheel set. The vehicle steering controller controls the second electric cylinder to work through the second electric cylinder controller to drive the second wheel set to turn. The second angle sensor obtains the rotation angle of the second wheel set. When the rotation angle of the second wheel set is equal to the theoretical rotation angle of the second wheel set, the steering operation of the rear steering system ends.

[0011] Furthermore, the vehicle steering controller calculates the first electric cylinder assist torque according to the torque signal, specifically including: Obtain the preset assist curve of the vehicle steering controller; According to the preset assist curve of the vehicle steering controller, obtain the assist characteristics of the first electric cylinder; The vehicle steering controller calculates the first electric cylinder assist torque according to the assist characteristics of the first electric cylinder and the torque signal.

[0012] Furthermore, the electric power steering controller calculates the electric power steering assist torque according to the torque signal, specifically including: Obtain the preset assist curve of the electric power steering controller; According to the preset assist curve of the electric power steering controller, obtain the assist characteristics of the electric power steering; The electric power steering controller calculates the electric power steering assist torque according to the assist characteristics of the electric power steering and the torque signal.

[0013] Furthermore, when the rotation angle of the first wheel set is equal to the preset angle, the steering operation of the front steering system ends, specifically including: When the rotation angle of the first wheel set is equal to the preset angle, the driver reduces the steering torque so that the sum of the first electric cylinder assist torque and the electric power steering assist torque is not greater than the resistance torque of the first wheel set, and the first wheel set stops steering, and the steering operation of the front steering system ends.

[0014] In a third aspect, the present invention provides a crane, including the electric steering system described in the first aspect.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention: This electric steering system uses pure electric assist, solves the problems that are difficult to avoid in the hydraulic system, reduces the vibration during vehicle steering, is not likely to generate abnormal noises, and avoids the use of hydraulic oil, thereby avoiding damage to hydraulic components, and is more in line with the development trend of intelligent vehicles. The steering assist of the present invention has a fast response. When the first electric cylinder assist fails, the electric power steering can act as an emergency steering assist source, improving the reliability and safety of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a three-dimensional structural schematic diagram of an electric steering system according to an embodiment of the present invention; Figure 2 is a three-dimensional structural schematic diagram of a rocker arm according to an embodiment of the present invention; Figure 3 is a control logic diagram of a front steering system according to an embodiment of the present invention; Figure 4It is a schematic diagram of the control logic of the rear steering system provided by an embodiment of the present invention.

[0017] In the figure: 1, steering wheel; 2, steering column; 3, electric power steering gear; 4, steering tie rod; 5, first electric cylinder; 6, steering drag link; 7, rocker arm; 8, first push rod; 9, second push rod; 10, first wheel set; 11, front axle. Specific embodiments

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0019] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0020] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations. Embodiment 1:

[0021] As Figure 1As shown in the figure, the present invention provides an electric steering system, including a front steering system and a rear steering system. The front steering system includes a steering wheel 1 and a front axle 11. The steering wheel 1 is movably connected to an electric steering gear 3 through a steering column 2. A steering pitman arm 6 is movably connected to the electric steering gear 3. A first wheel set 10 and a first electric cylinder 5 are rotatably connected to the front axle 11. The steering pitman arm 6 is movably connected to the first wheel set 10 through a steering tie rod 4. The output end of the first electric cylinder 5 is rotatably connected to the first wheel set 10. The rear steering mechanism includes a second electric cylinder and a rear axle. A second wheel set and the second electric cylinder are rotatably connected to the rear axle. The output end of the second electric cylinder is rotatably connected to the second wheel set.

[0022] Specifically, when the front steering system performs steering work, the driver drives the steering wheel 1 to rotate. The steering wheel 1 drives the electric steering gear 3 to move through the steering column 2. The electric steering gear 3 drives the first wheel set 10 to swing through the steering pitman arm 6 and the steering tie rod 4. The front axle 11 plays a supporting role for the first wheel set 10. At the same time, the first electric cylinder 5 starts to work and pushes the first wheel set 10 to swing. At this time, the first electric cylinder 5 and the steering tie rod 4 cooperate to jointly push the first wheel set 10 to swing, realizing vehicle steering. Due to the existence of the steering tie rod 4 and there are two power assist sources (the electric steering gear 3 and the first electric cylinder 5) in this system, when the power assist of the first electric cylinder 5 fails, the electric steering gear 3 can act as an emergency steering power assist source. The rear steering system is a pure electric steering. According to the preset relationship, the displacement of the second electric cylinder of the rear axle is calculated based on the rotation angle of the front axle 11. The second electric cylinder is arranged in the rear steering system and can control the rotation angle of the second wheel set through telescoping, so as to realize the steering of the rear axle.

[0023] The present invention adopts pure electric power assist, solves the problems that are difficult to avoid in the hydraulic system, reduces the vibration during vehicle steering, is not easy to generate abnormal noises, and avoids the use of hydraulic oil, thereby avoiding damage to hydraulic components, and is more in line with the development trend of intelligent vehicles. The steering power assist of the present invention has a fast response. When the power assist of the first electric cylinder 5 fails, the electric steering gear 3 can act as an emergency steering power assist source, improving the reliability and safety of the present invention.

[0024] As Figure 2 shown, in an embodiment, the steering pitman arm 6 is movably connected to the first wheel set 10 through a pushing mechanism. The pushing mechanism includes a rocker arm 7 rotatably arranged inside the vehicle frame. A first push rod 8 is rotatably connected between the rocker arm 7 and the steering pitman arm 6. A second push rod 9 is rotatably connected between the rocker arm 7 and the first wheel set 10. The first electric cylinder 5 is rotatably arranged on the inner wall of the vehicle frame (not shown in the figure). The output end of the first electric cylinder 5 is rotatably connected to the rocker arm 7.

[0025] Specifically, when the first electric cylinder 5 operates, it can push the rocker arm 7 to rotate, thereby driving the first push rod 8 and the second push rod 9 to move. At this time, the first electric cylinder 5 cooperates with the electric steering gear 3 to push the first wheel set 10 to swing, realizing the steering of the front axle 11, and there are two power assist sources in this system (the electric steering gear 3 and the first electric cylinder 5).

[0026] An embodiment, the front steering system further includes a vehicle steering controller, the vehicle steering controller is electrically connected to an electric steering gear controller, a first electric cylinder controller and a first angle sensor, the electric steering gear controller is electrically connected to the electric steering gear 3, the first electric cylinder controller is electrically connected to the first electric cylinder 5, the first angle sensor (not shown in the figure) is installed on the first wheel set 10, the rear steering system further includes a second electric cylinder controller and a second angle sensor, the second electric cylinder controller is electrically connected to the second electric cylinder, the second angle sensor is installed on the second wheel set, and both the second electric cylinder controller and the second angle sensor are electrically connected to the vehicle steering controller.

[0027] Specifically, the electric steering gear controller is used to control the electric steering gear 3, the first electric cylinder controller is used to control the first electric cylinder 5, the first angle sensor is used to detect the rotation angle of the first wheel set 10, the second electric cylinder controller is used to control the second electric cylinder, and the second angle sensor is used to detect the rotation angle of the second wheel set. Embodiment Two:

[0028] The present invention provides an electric steering method, based on the electric steering system described in Embodiment One, including the working method of the front steering system and the working method of the rear steering system. The working method of the front steering system includes the following steps: The driver drives the steering wheel 1 to turn, and inputs the steering torque to the electric steering gear 3; The electric steering gear 3 obtains a torque signal according to the steering torque, and transmits the torque signal to the vehicle steering controller and the electric steering gear controller; The vehicle steering controller calculates the first electric cylinder assist torque according to the torque signal, and controls the first electric cylinder 5 to operate. The electric steering gear controller calculates the electric steering gear assist torque according to the torque signal, and controls the electric steering gear 3 to operate; The driver adjusts the steering torque so that the sum of the first electric cylinder assist torque and the electric steering gear assist torque is greater than the resistance torque of the first wheel set 10 to drive the first wheel set 10 to turn; The first angle sensor obtains the rotation angle of the first wheel set 10. When the rotation angle of the first wheel set 10 is equal to the preset angle, the steering operation of the front steering system ends.

[0029] As Figure 3As shown in the figure, specifically, when the driver operates the steering wheel 1 to turn, the steering torque input by the driver is transmitted to the electric power steering gear 3 through the steering column 2. The electric power steering gear 3 is internally equipped with a torque sensor. After the torque sensor recognizes the steering torque input by the driver, it obtains a torque signal and transmits the torque signal to both the vehicle steering controller and the electric power steering gear controller simultaneously. In the vehicle steering controller and the electric power steering gear controller, a boost curve is preset. The boost curve of the vehicle steering controller is the boost characteristic of the first electric cylinder 5, and the boost curve of the electric power steering gear controller is the boost characteristic of the electric power steering gear 3. After the torque signal is processed, according to the boost characteristic, the first electric cylinder 5 outputs the first electric cylinder boost torque, and the electric power steering gear 3 outputs the electric power steering gear boost torque. The two boost torques are transmitted to the first wheel set 10 through the mechanical linkage in the front steering system. The driver adjusts the steering torque in real time. When the sum of the two boost torques is greater than the sum of the resistance torques of the vehicle front axle 11, the vehicle front axle 11 turns. When the rotation angle of the vehicle's first wheel set 10 reaches the angle preset by the driver, the driver reduces the steering torque input to the steering wheel 1, and the two boost torques of the front steering system decay. When it is less than the resistance torque, the front axle 11 stops turning and the steering process ends; the front steering system changes with the driver's steering torque and provides a boost torque output in real time to affect the rotation angle of the first wheel set 10. At the same time, because the steering method of the front steering system is mechanical steering and the electric power steering gear 3 and the first electric cylinder 5 are boost components, when the electric power steering gear 3 or the first electric cylinder 5 fails, the driver can use the hand force of a person and the remaining boost source through the mechanical system to perform emergency steering together, greatly increasing the safety and reliability of this system.

[0030] An embodiment, the working method of the rear steering system specifically includes: The first angle sensor transmits the rotation angle of the first wheel set 10 to the vehicle steering controller; The vehicle steering controller calculates the theoretical rotation angle of the second wheel set according to the preset steering mode and the rotation angle of the first wheel set 10; The vehicle steering controller controls the second electric cylinder to work through the second electric cylinder controller to drive the second wheel set to turn; The second angle sensor obtains the rotation angle of the second wheel set. When the rotation angle of the second wheel set is equal to the theoretical rotation angle of the second wheel set, the steering work of the rear steering system ends.

[0031] As Figure 4As shown, specifically, a truck crane has multiple steering modes, such as a small turning mode, a crab walking mode, a rear axle locking mode, a road driving mode, etc.; the rear steering system mainly relies on the second electric cylinder controller to control the telescopic movement of the second electric cylinder to achieve rear axle steering; when the front axle 11 steers, the first angle sensor sends the rotation angle signal to the vehicle steering controller. The vehicle steering controller selects the corresponding front and rear axle rotation angle relationship according to the preset steering mode, calculates the theoretical rotation angle of the rear axle, controls the operation of the second electric cylinder motor, makes the second electric cylinder telescopic, generates displacement, and the rear axle is also provided with a second angle sensor. The second angle sensor real-time feeds back the rotation angle to the vehicle steering controller. The vehicle steering controller compares whether the front axle 11 rotation angle and the rear axle rotation angle signal meet the preset relationship, and continues to make the second electric cylinder work according to the error value to adjust the rear axle rotation angle to complete the steering process; there is no mechanical connection between the front and rear steering systems, and only a power source, that is, the second electric cylinder, is arranged on the rear axle. The rear axle steering is controlled by the controller algorithm and the sensor, and the steering is more accurate; when a fault occurs in the rear steering system, the rear steering axle can be locked by the electric cylinder brake, so that the rear steering axle is locked in the current position to prevent the negative impact caused by the out-of-control rear axle steering.

[0032] An embodiment, the vehicle steering controller calculates the first electric cylinder assist torque according to the torque signal, specifically including: Obtain the preset assist curve of the vehicle steering controller; According to the preset assist curve of the vehicle steering controller, obtain the assist characteristics of the first electric cylinder 5; The vehicle steering controller calculates the first electric cylinder assist torque according to the assist characteristics of the first electric cylinder 5 and the torque signal.

[0033] An embodiment, the electric steering gear controller calculates the electric steering gear assist torque according to the torque signal, specifically including: Obtain the preset assist curve of the electric steering controller; According to the preset assist curve of the electric steering controller, obtain the assist characteristics of the electric steering gear 3; The electric steering gear controller calculates the electric steering gear assist torque according to the assist characteristics of the electric steering gear 3 and the torque signal.

[0034] An embodiment, when the rotation angle of the first wheel set 10 is equal to the preset angle, the steering work of the front steering system ends, specifically including: When the rotation angle of the first wheel set 10 is equal to the preset angle, the driver reduces the steering torque, so that the sum of the first electric cylinder assist torque and the electric steering gear assist torque is not greater than the resistance torque of the first wheel set 10, and the first wheel set 10 stops steering, and the steering work of the front steering system ends. Embodiment Three:

[0035] The present invention provides a crane, including the electric steering system described in Embodiment 1.

[0036] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. An electric power steering system, characterized in that, It includes a front steering system and a rear steering system. The front steering system includes a steering wheel and a front axle. The steering wheel is movably connected to an electric power steering (EPS) through a steering column. A steering pitman arm is movably connected to the EPS. A first wheel set and a first electric cylinder are rotatably connected to the front axle. The steering pitman arm is movably connected to the first wheel set through a steering tie rod. The output end of the first electric cylinder is rotatably connected to the first wheel set. The rear steering mechanism includes a second electric cylinder and a rear axle. A second wheel set and the second electric cylinder are rotatably connected to the rear axle. The output end of the second electric cylinder is rotatably connected to the second wheel set.

2. The electric power steering system according to claim 1, wherein, The steering pitman arm is movably connected to the first wheel set through a pushing mechanism. The pushing mechanism includes a rocker arm rotatably arranged inside the vehicle frame. A first push rod is rotatably connected between the rocker arm and the steering pitman arm. A second push rod is rotatably connected between the rocker arm and the first wheel set. The first electric cylinder is rotatably arranged on the inner wall of the vehicle frame. The output end of the first electric cylinder is rotatably connected to the rocker arm.

3. The electric power steering system according to claim 1, wherein The front steering system further includes a vehicle steering controller, which is electrically connected to an EPS controller, a first electric cylinder controller, and a first angle sensor. The EPS controller is electrically connected to the EPS. The first electric cylinder controller is electrically connected to the first electric cylinder. The first angle sensor is installed on the first wheel set.

4. The electric power steering system according to claim 3, characterized in that The rear steering system further includes a second electric cylinder controller and a second angle sensor. The second electric cylinder controller is electrically connected to the second electric cylinder. The second angle sensor is installed on the second wheel set. Both the second electric cylinder controller and the second angle sensor are electrically connected to the vehicle steering controller.

5. An electric steering method, based on the electric steering system according to claim 4, characterized in that It includes the working methods of the front steering system and the rear steering system. The working method of the front steering system includes the following steps: The driver turns the steering wheel to input a steering torque to the EPS. The EPS obtains a torque signal according to the steering torque and transmits the torque signal to the vehicle steering controller and the EPS controller. The vehicle steering controller calculates the assisting torque of the first electric cylinder according to the torque signal and controls the first electric cylinder to work. The EPS controller calculates the assisting torque of the EPS according to the torque signal and controls the EPS to work. The driver adjusts the steering torque so that the sum of the assisting torque of the first electric cylinder and the assisting torque of the EPS is greater than the resistance torque of the first wheel set to drive the first wheel set to turn. The first angle sensor obtains the rotation angle of the first wheel set. When the rotation angle of the first wheel set is equal to the preset angle, the steering work of the front steering system ends.

6. The electric steering method according to claim 5, wherein The working method of the rear steering system specifically includes: The first angle sensor transmits the rotation angle of the first wheel set to the vehicle steering controller. The vehicle steering controller calculates the theoretical rotation angle of the second wheel set according to the preset steering mode and the rotation angle of the first wheel set. The vehicle steering controller controls the second electric cylinder to work through the second electric cylinder controller to drive the second wheel set to turn. The second angle sensor obtains the rotation angle of the second wheel set. After the rotation angle of the second wheel set is equal to the theoretical rotation angle of the second wheel set, the steering operation of the rear steering system ends.

7. The electric steering method according to claim 5, characterized in that The vehicle steering controller calculates the first electric cylinder assist torque according to the torque signal, specifically including: Obtaining the preset assist curve of the vehicle steering controller; Obtaining the assist characteristics of the first electric cylinder according to the preset assist curve of the vehicle steering controller; The vehicle steering controller calculates the first electric cylinder assist torque according to the assist characteristics of the first electric cylinder and the torque signal.

8. The electric steering method according to claim 5, characterized in that The electric steering gear controller calculates the electric steering gear assist torque according to the torque signal, specifically including: Obtaining the preset assist curve of the electric steering controller; Obtaining the assist characteristics of the electric steering gear according to the preset assist curve of the electric steering controller; The electric steering gear controller calculates the electric steering gear assist torque according to the assist characteristics of the electric steering gear and the torque signal.

9. The electric steering method according to claim 5, characterized in that, When the rotation angle of the first wheel set is equal to the preset angle, the steering operation of the front steering system ends, specifically including: When the rotation angle of the first wheel set is equal to the preset angle, the driver reduces the steering torque so that the sum of the first electric cylinder assist torque and the electric steering gear assist torque is not greater than the resistance torque of the first wheel set, and the first wheel set stops steering, and the steering operation of the front steering system ends.

10. A crane, characterized in that, Including the electric steering system according to any one of claims 1 to 4.

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