Electric power steering device and control method thereof

Abstract

The application discloses an electric power steering device, and belongs to the technical field of vehicles. The electric power steering device comprises a steering mechanical system, a hydraulic power assisting system and an electric control system. The hydraulic power assisting system comprises a front group power assisting cylinder and a centering power assisting cylinder. The steering mechanical system is used for transmitting the force of the front group power assisting cylinder to the front wheels of the vehicle and transmitting the force of the centering power assisting cylinder to the rear wheels of the vehicle. The steering mechanical system comprises a steering gear. The hydraulic power assisting system is used for controlling the front group power assisting cylinder according to the input shaft rotation angle of the steering gear, so that the front wheels of the vehicle are steered. The electric control system is used for determining the steering mode of the vehicle and sending corresponding control instructions to the hydraulic power assisting system according to the steering mode of the vehicle. The hydraulic power assisting system is used for controlling the centering power assisting cylinder according to the control instructions, so that the rear wheels of the vehicle are steered or centered. The electric power steering device can control the rotation of the front wheels and the rear wheels of the vehicle respectively, so that the vehicle enters different steering modes, thereby guaranteeing the safety and stability of the vehicle during driving.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to an electric power steering device and its control method. Background Technology

[0002] With the continuous advancement of society, economy, and automotive technology, automobiles are becoming increasingly common. During vehicle operation, steering control plays a crucial role in ensuring driving safety and stability, as well as reducing the vehicle's turning radius.

[0003] Traditional car steering systems involve front-wheel steering, with the rear wheels not participating in steering; most electric vehicles also use this type of steering system. This type of steering system results in a large turning radius and inflexible steering, especially in confined spaces like busy urban areas or parking lots, where vehicle steering is significantly restricted. Furthermore, at high speeds, relying solely on front-wheel steering can easily lead to skidding and accidents. This negatively impacts vehicle safety and stability.

[0004] Furthermore, for safety reasons, overweight vehicles are also equipped with emergency steering systems. These systems provide steering fluid when the steering pump fails to deliver pressure. Traditional cars typically install emergency pumps in the transmission, transfer case, or axle. While current electric vehicles are not yet very heavy, the trend is towards heavier vehicles. Equipping heavy-duty electric vehicles with emergency steering systems is an inevitable trend. Therefore, meeting the steering needs of different vehicles under various driving conditions is a pressing issue that needs to be addressed. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide an electric steering device and its control method that overcome or at least partially solve the above problems.

[0006] In one aspect, an electric steering device is provided, including a steering mechanical system, a hydraulic power assist system, and an electronic control system;

[0007] The hydraulic power steering system includes a front power steering cylinder and a centering power steering cylinder, which are connected to the steering mechanism system. The steering mechanism system transmits the force from the front power steering cylinder to the front wheels of the vehicle and the force from the centering power steering cylinder to the rear wheels of the vehicle. The steering mechanism system includes a steering gear, and the hydraulic power steering system controls the front power steering cylinder according to the input shaft angle of the steering gear, thereby steering the front wheels of the vehicle.

[0008] The electronic control system is used to determine the vehicle's steering mode and send corresponding control commands to the hydraulic power steering system according to the vehicle's steering mode, so that the vehicle enters the corresponding steering mode; wherein, the vehicle's steering modes include: front group steering mode, front and rear group opposite steering mode, front and rear group same-direction steering mode, rear group follow-up mode, and emergency steering mode.

[0009] The hydraulic power steering system is used to control the centering assist cylinder according to the control command, so that the rear wheels of the vehicle are steered or centered.

[0010] Optionally, the hydraulic power assist system includes a front power assist subsystem, a rear power assist subsystem, and a centering power assist subsystem;

[0011] The front power steering control subsystem is used to control the front power steering cylinder according to the input shaft angle of the steering gear, so as to change the rotation angle and rotation direction of the front wheels and provide steering assistance for the rotation of the front wheels.

[0012] The rear power assist control subsystem is used to control the centering assist cylinder to change the rotation angle and rotation direction of the rear wheel;

[0013] The centering assist subsystem is used to control the centering assist cylinder to center the rear wheels of the vehicle.

[0014] Optionally, the front power steering subsystem includes a high-pressure electric power steering pump, a front power steering cylinder, and a power steering fluid reservoir;

[0015] The oil inlet of the high-pressure electric steering pump is connected to the power steering oil tank, the oil outlet of the high-pressure electric steering pump is connected to the oil inlet of the steering gear, the first working oil port of the steering gear is connected to the rod chamber oil port of the front power assist cylinder, the rodless chamber oil port of the front power assist cylinder is connected to the second working oil port of the steering gear, and the oil return port of the steering gear is connected to the power steering oil tank.

[0016] The oil inlet of the steering gear is connected to either the first working oil port or the second working oil port according to the direction of steering wheel rotation, and the oil return port of the steering gear is connected to either the second working oil port or the first working oil port according to the direction of steering wheel rotation.

[0017] Optionally, the rear power steering subsystem includes a low-pressure electric steering pump, a proportional directional valve, a centering assist cylinder, and a power steering fluid reservoir.

[0018] The inlet of the low-pressure electric steering pump is connected to the power steering fluid reservoir, the outlet of the low-pressure electric steering pump is connected to the inlet of the proportional directional valve, the first working port of the proportional directional valve is connected to the first working port of the centering assist cylinder, the second working port of the centering assist cylinder is connected to the second working port of the proportional directional valve, and the outlet of the proportional directional valve is connected to the power steering fluid reservoir.

[0019] The proportional directional valve is a three-position four-way electro-hydraulic proportional composite control solenoid valve. The proportional directional valve is equipped with an amplifier. The output terminal of the amplifier is connected to the control terminal of the proportional directional valve, and the input terminal of the amplifier is connected to the electronic control system.

[0020] Optionally, the centering assist subsystem includes a high-pressure electric steering pump, a low-pressure electric steering pump, a pressure reducing valve, a first check valve, an accumulator, a second check valve, a centering solenoid valve, an overflow valve, a centering assist cylinder, a power steering oil tank, and a third check valve.

[0021] The oil inlet of the high-pressure electric steering pump and the oil inlet of the low-pressure electric steering pump are both connected to the power steering oil tank. The oil inlet of the third check valve is connected to the oil outlet of the low-pressure electric steering pump, and the oil outlet of the third check valve is connected to the oil outlet of the high-pressure electric steering pump.

[0022] The inlet of the pressure reducing valve is connected to the outlet of the high-pressure electric power steering pump; the outlet of the pressure reducing valve is connected to the inlet of the first one-way valve; the outlet of the first one-way valve is connected to the inlet of the second one-way valve; the outlet of the second one-way valve is connected to the inlet of the centering solenoid valve; the drain port of the centering solenoid valve is connected to the power steering reservoir; the first working port of the centering solenoid valve is connected to the third and fourth working ports of the centering assist cylinder; the drain port of the centering assist cylinder is connected to the power steering reservoir; the inlet of the overflow valve is connected to the first working port of the centering solenoid valve; the outlet of the overflow valve is connected to the power steering reservoir; and the accumulator is connected between the first one-way valve and the second one-way valve.

[0023] The high-pressure electric steering pump is powered by a high-pressure power supply system, and the low-pressure electric steering pump is powered by a low-pressure power supply system.

[0024] Optionally, the steering mechanism further includes a rocker arm, a tie rod, a front trapezoidal mechanism, and a rear trapezoidal mechanism;

[0025] The rocker arm is connected to the steering gear. One end of the straight tie rod is connected to the end of the rocker arm away from the steering gear, and the other end of the straight tie rod is connected to the front trapezoidal mechanism. The two ends of the front trapezoidal mechanism are connected to the front wheels of the vehicle, and the straight tie rod drives the front wheels of the vehicle to rotate. The two ends of the rear trapezoidal mechanism are connected to the rear wheels of the vehicle.

[0026] Optionally, the front trapezoidal mechanism includes a first trapezoidal arm, a second trapezoidal arm, and a first horizontal tie rod;

[0027] The first trapezoidal arm and the second trapezoidal arm are respectively connected to the two ends of the first crossbar, and the end of the first trapezoidal arm away from the first crossbar and the end of the second trapezoidal arm away from the first crossbar are respectively connected to the two front wheels of the vehicle.

[0028] Optionally, the rear trapezoidal mechanism includes a third trapezoidal arm, a fourth trapezoidal arm, and a second horizontal tie rod;

[0029] The third trapezoidal arm and the fourth trapezoidal arm are respectively connected to the two ends of the second crossbar, and the end of the third trapezoidal arm away from the second crossbar and the end of the fourth trapezoidal arm away from the second crossbar are respectively connected to the two rear wheels of the vehicle.

[0030] Optionally, the electronic control system is also used for:

[0031] Obtain vehicle status information, which includes at least front wheel steering angle information, rear wheel steering angle information, vehicle speed information, and transmission gear information;

[0032] The vehicle's steering mode is determined based on the vehicle's status information.

[0033] Secondly, a control method for an electric steering device is provided, applicable to the electric steering device as described in the first aspect, the control method comprising:

[0034] Determine the vehicle's steering mode;

[0035] According to the vehicle's steering mode, a corresponding control command is sent to the hydraulic power steering system to cause the vehicle to enter the corresponding steering mode.

[0036] The vehicle's steering modes include: front group steering mode, front and rear group opposite steering mode, front and rear group same-direction steering mode, rear group follow-up mode, and emergency steering mode.

[0037] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0038] This invention provides an electric steering device and its control method, comprising a steering mechanical system, a hydraulic power assist system, and an electronic control system. The steering mechanical system transmits the forces of the front power assist cylinder and the centering power assist cylinder to the front and rear wheels of a vehicle, respectively, to achieve steering of the front and rear wheels. The hydraulic power assist system controls the front power assist cylinder according to the input shaft angle of the steering gear, causing the front wheels to steer and providing steering assistance. The electronic control system determines the vehicle's steering mode and sends corresponding control commands to the hydraulic power assist system based on the steering mode. This allows the hydraulic power assist system to control the centering power assist cylinder accordingly, causing the rear wheels to steer or center, thereby enabling the vehicle to enter the corresponding steering mode and meeting the steering needs of the vehicle under different driving conditions, thus ensuring the safety and stability of vehicle operation.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0041] In the attached diagram:

[0042] Figure 1 This is a structural block diagram of an electric steering device provided in an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of a steering mechanism system provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the structure of a front trapezoidal mechanism provided in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the structure of a rear trapezoidal mechanism provided in an embodiment of the present invention;

[0046] Figure 5 This is a hydraulic schematic diagram of a hydraulic power assist system provided in an embodiment of the present invention;

[0047] Figure 6 This is a flowchart of the judgment logic for automatically determining the steering mode provided in an embodiment of the present invention;

[0048] Figure 7This is a flowchart of the judgment logic for manually selecting a steering mode provided in an embodiment of the present invention;

[0049] Figure 8 This is a flowchart of a control method for an electric steering device provided in an embodiment of the present invention. Detailed Implementation

[0050] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0051] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0052] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0053] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0054] Figure 1 This is a structural block diagram of an electric steering device provided in an embodiment of the present invention, such as... Figure 1 As shown, the electric steering system 100 includes a steering mechanical system 10, a hydraulic power assist system 20, and an electronic control system 30.

[0055] The hydraulic power steering system 20 includes a front power steering cylinder 21 and a centering power steering cylinder 22, which are connected to the steering mechanism system 10. The steering mechanism system 10 transmits the force of the front power steering cylinder 21 to the front wheels of the vehicle and the force of the centering power steering cylinder 22 to the rear wheels of the vehicle. The steering mechanism system 10 includes a steering gear 11, and the hydraulic power steering system 20 controls the front power steering cylinder 21 according to the input shaft angle of the steering gear 11, thereby steering the front wheels of the vehicle.

[0056] The electronic control system 30 is used to determine the vehicle's steering mode and send corresponding control commands to the hydraulic power steering system 20 according to the vehicle's steering mode, so that the vehicle enters the corresponding steering mode. The vehicle's steering modes include: front group steering mode, front and rear group opposite steering mode, front and rear group same-direction steering mode, rear group follow-up mode, and emergency steering mode.

[0057] The hydraulic power steering system 20 is used to control the centering assist cylinder 22 according to the control command, so as to make the rear wheels of the vehicle steer or center the rear wheels of the vehicle.

[0058] In the electric steering device provided in this embodiment of the invention, the steering mechanism can transmit the forces of the front power assist cylinder and the centering power assist cylinder to the front and rear wheels of the vehicle, respectively, to achieve steering of the front and rear wheels. The hydraulic power assist system can control the front power assist cylinder according to the input shaft angle of the steering gear, causing the front wheels of the vehicle to steer and providing steering assistance for the rotation of the front wheels. The electronic control system can determine the steering mode of the vehicle and send corresponding control commands to the hydraulic power assist system according to the steering mode, so that the hydraulic power assist system can control the centering power assist cylinder accordingly, causing the rear wheels of the vehicle to steer or center, thereby enabling the vehicle to enter the corresponding steering mode, meeting the steering needs of the vehicle under different driving conditions, and ensuring the safety and stability of vehicle driving.

[0059] Figure 2 This is a structural schematic diagram of a steering mechanism system provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the steering mechanism system 10 includes a steering gear 11, a rocker arm 12, a tie rod 13, a front trapezoidal mechanism 14, and a rear trapezoidal mechanism 15.

[0060] The rocker arm 12 is connected to the steering gear 11. One end of the tie rod 13 is connected to the end of the rocker arm 12 furthest from the steering gear 11, and the other end of the tie rod 13 is connected to the front trapezoidal mechanism 14. Both ends of the front trapezoidal mechanism 14 are connected to the front wheels of the vehicle, and the tie rod 13 drives the front wheels to rotate. Both ends of the rear trapezoidal mechanism 15 are connected to the rear wheels of the vehicle.

[0061] The steering gear 11 is a crucial component of the steering system 10 for vehicle steering. Its main function is to increase the force transmitted from the steering wheel to the steering transmission mechanism and change the direction of force transmission. There are many types of steering gears 11, such as power steering gears. The specific type and model can be designed and installed according to actual needs; this embodiment does not impose specific limitations. In one implementation of this embodiment, one end of the steering gear 11 and the rocker arm 12 can be connected via a spline. The rotation of the output shaft of the steering gear 11 drives the rocker arm 12 to swing. The other end of the rocker arm 12 is connected to one end of the tie rod 13 via a tapered hole.

[0062] Figure 3 This is a structural schematic diagram of a front trapezoidal mechanism provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the front trapezoidal mechanism 14 includes a first trapezoidal arm 141, a second trapezoidal arm 142, and a first horizontal tie rod 143.

[0063] The first trapezoidal arm 141 and the second trapezoidal arm 142 are respectively connected to the two ends of the first horizontal tie rod 143, and the end of the first trapezoidal arm 141 away from the first horizontal tie rod 143 and the end of the second trapezoidal arm 141 away from the first horizontal tie rod 143 are respectively connected to the two front wheels of the vehicle.

[0064] In this embodiment, the front trapezoidal mechanism 14 further includes a first support 144, the cylinder body of the front booster cylinder 21 is fixed by the first support 144, and the piston rod is connected to the second trapezoidal arm 142. When the piston rod in the front booster cylinder 21 moves, it will drive the second trapezoidal arm 142 to move, thereby driving the entire front trapezoidal mechanism 14 to rotate, so that the front wheels of the vehicle are steered.

[0065] Figure 4 This is a structural schematic diagram of a rear trapezoidal mechanism provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the rear trapezoidal mechanism 15 includes a third trapezoidal arm 151, a fourth trapezoidal arm 152, and a second horizontal tie rod 153.

[0066] The third trapezoidal arm 151 and the fourth trapezoidal arm 152 are respectively connected to the two ends of the second crossbar 153, and the end of the third trapezoidal arm 151 away from the second crossbar 153 and the end of the fourth trapezoidal arm 152 away from the second crossbar 153 are respectively connected to the two rear wheels of the vehicle.

[0067] In this embodiment, the rear trapezoidal mechanism 15 further includes a second support 154, through which the cylinder body of the centering assist cylinder 22 is fixed, and the piston rod is connected to the fourth trapezoidal arm 152. When the piston rod inside the centering assist cylinder 22 moves, it drives the fourth trapezoidal arm 152 to move, thereby driving the entire rear trapezoidal mechanism 15 to rotate, causing the rear wheels of the vehicle to steer or center.

[0068] Optionally, the hydraulic power assist system 20 includes a front power assist subsystem, a rear power assist subsystem, and a centering power assist subsystem.

[0069] The front power steering control subsystem controls the front power steering cylinders based on the steering gear input shaft angle to change the rotation angle and direction of the front wheels, providing steering assistance. The rear power steering control subsystem controls the centering power steering cylinders to change the rotation angle and direction of the rear wheels. The centering power steering subsystem controls the centering power steering cylinders to center the vehicle's rear wheels.

[0070] Figure 5 This is a hydraulic schematic diagram of a hydraulic power assist system provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the front power steering subsystem includes a front power steering cylinder 21, a high-pressure electric power steering pump 23, and a power steering fluid reservoir 24.

[0071] The inlet of the high-pressure electric power steering pump 23 is connected to the power steering oil tank 24, the outlet of the high-pressure electric power steering pump 23 is connected to the inlet P of the steering gear 11, the first working oil port A of the steering gear 11 is connected to the rod chamber oil port of the front power steering cylinder 21, the rodless chamber oil port of the front power steering cylinder 21 is connected to the second working oil inlet B of the steering gear 11, and the return oil port T of the steering gear 11 is connected to the power steering oil tank 24.

[0072] The oil inlet P of the steering gear 11 is connected to either the first working oil port A or the second working oil port B according to the direction of steering wheel rotation, and the oil return port T is connected to either the second working oil port A or the first working oil port B according to the direction of steering wheel rotation.

[0073] Optional, such as Figure 5 As shown, the rear power steering subsystem includes a low-pressure electric steering pump 25, a proportional directional valve 26, a centering assist cylinder 22, and a power steering reservoir 24.

[0074] The inlet of the low-pressure electric power steering pump 25 is connected to the power steering oil reservoir 24, the outlet of the low-pressure electric power steering pump 25 is connected to the inlet P of the proportional directional valve 26, the first working port A of the proportional directional valve 26 is connected to the first working port A1 of the centering assist cylinder 22, the second working port B1 of the centering assist cylinder 22 is connected to the second working port B of the proportional directional valve 26, and the outlet T of the proportional directional valve 26 is connected to the power steering oil reservoir 24.

[0075] The proportional directional valve 26 is a three-position, four-way electro-hydraulic proportional composite control solenoid valve. The proportional directional valve 26 is equipped with an amplifier; the output of the amplifier is connected to the control terminal of the proportional directional valve 26, and the input of the amplifier is connected to the electronic control system 30. The spool function of the proportional directional valve 26 is W-type.

[0076] In this embodiment, the positive input of the amplifier can be used to receive control commands sent by the electronic control system 30, and the negative input of the amplifier can be used to receive feedback signals. The control commands are used to control the theoretical rotation angle of the vehicle's rear wheels, and the feedback signals are used to provide feedback on the actual rotation angle of the vehicle's rear wheels. By acquiring the feedback signals, the actual rotation angle of the vehicle's rear wheels can be made closer to the theoretical rotation angle, thereby achieving more precise control of the rear wheels.

[0077] Optional, such as Figure 5 As shown, the centering assist subsystem includes a high-pressure electric steering pump 23, a low-pressure electric steering pump 25, a pressure reducing valve 27, a first check valve V1, an accumulator 28, a second check valve V2, a centering solenoid valve 29, an overflow valve 291, a centering assist cylinder 22, a power steering oil tank 24, and a third check valve V3.

[0078] The inlet of the high-pressure electric power steering pump 23 and the inlet of the low-pressure electric power steering pump 25 are both connected to the power steering oil tank 24. The inlet of the third check valve V3 is connected to the outlet of the low-pressure electric power steering pump 25, and the outlet of the third check valve V3 is connected to the outlet of the high-pressure electric power steering pump 23.

[0079] The inlet of pressure reducing valve 27 is connected to the outlet of high-pressure electric power steering pump 23. The outlet of pressure reducing valve 27 is connected to the inlet of first check valve V1. The outlet of first check valve V1 is connected to the inlet of second check valve V2. The outlet of second check valve V2 is connected to the inlet P of centering solenoid valve 29. The drain port T of centering solenoid valve 29 is connected to power steering reservoir 24. The first working port A of centering solenoid valve 29 is connected to the third working port A2 and the fourth working port B2 of centering assist cylinder 22. The second working port B of centering solenoid valve 29 is closed. The drain port T of centering assist cylinder 22 is connected to power steering reservoir 24. The inlet of overflow valve 291 is connected to the first working port A of centering solenoid valve 29. The outlet of overflow valve 291 is connected to power steering reservoir 24. Accumulator 28 is connected between first check valve V1 and second check valve V2.

[0080] The centering solenoid valve 29 is a two-position four-way valve, and its control terminal can be connected to the electronic control system 30. The centering solenoid valve 29 is configured such that: when de-energized, it is in its initial position, with its inlet P connected to the first working port A and its drain port T connected to the second working port B; when energized, its inlet P is connected to the second working port B, and its first working port A is connected to the drain port T.

[0081] The centering assist cylinder 22 has two non-communicating chambers (left chamber and right chamber). Four pistons are located in each chamber. The first piston is located in the left chamber, dividing it into two non-communicating sub-chambers (first sub-chamber and second sub-chamber). The assisting part of the centering assist cylinder 22—the first working port A1 and the second working port B1—communicates with the two sub-chambers in the left chamber. The second and third pistons are located in the right chamber, dividing it into three non-communicating sub-chambers (third sub-chamber, fourth sub-chamber, and fifth sub-chamber). The centering part of the centering assist cylinder 22—the third working port A2, the fourth working port B2, and the drain port T—communicates with the three sub-chambers in the right chamber. The fourth sub-chamber, where the drain port T is located, has a boss to restrict the movement of the second and third pistons. The fourth piston is located in the fourth sub-chamber. The first and fourth pistons are connected by a piston rod and move synchronously. The second piston is located in the third sub-chamber, fitted onto the piston rod, and can slide along the piston rod. The third piston is located in the fifth sub-chamber, fitted onto the piston rod, and can slide along the piston rod.

[0082] In this embodiment, the control terminals of both the high-pressure electric power steering pump 23 and the low-pressure electric power steering pump 25 are connected to the electronic control system 30. The high-pressure electric power steering pump 23 is powered by a high-voltage power supply system, and the low-pressure electric power steering pump 25 is powered by a low-voltage power supply system. This separation of high and low voltages improves the reliability of the steering system. An overflow valve 291 prevents excessive hydraulic pressure in the centering assist subsystem.

[0083] It should be noted that the third one-way valve V3 functions as follows: In emergency steering mode, it directs the pressurized oil from the low-pressure electric power steering pump into the front power steering control subsystem to achieve emergency steering. In front-rear reverse steering mode and front-rear same-direction steering mode, it guides the pressurized oil back to the power steering reservoir through the steering gear during the start-up of the steering pump, reducing the starting pressure. When the electronic control system issues a control command to reduce the rear wheel steering angle to zero, it guides the pressurized oil back to the power steering reservoir through the steering gear.

[0084] Optionally, the electronic control system 30 is also used for:

[0085] Obtain vehicle status information, which includes at least front wheel steering angle information, rear wheel steering angle information, vehicle speed information, and transmission gear information;

[0086] The vehicle's steering mode is determined based on the vehicle's status information.

[0087] Specifically, the electronic control system 30 may include: a front wheel angle sensor, a rear wheel angle sensor, a vehicle speed detection sensor, a vehicle controller, and a display screen. The front wheel angle sensor detects front wheel steering angle information. The rear wheel angle sensor detects rear wheel steering angle information, and the vehicle speed detection sensor detects vehicle speed information. The vehicle controller acquires the front wheel steering angle information, rear wheel steering angle information, vehicle speed information, vehicle transmission gear information, and status information of the high-voltage and low-voltage electric power steering pumps from the bus. Then, through a steering control logic algorithm, it determines the vehicle's steering mode, calculates the theoretical rotation angle and direction of the rear wheels based on the steering mode, and issues control commands to control the rear wheels to steer accordingly. The display screen can be used to display the acquired vehicle status information or steering mode, etc.

[0088] To better understand this invention, the following is combined with... Figure 5 Here's a brief explanation of how the hydraulic power steering system works in different steering modes:

[0089] Front steering mode: In this mode, the front power steering subsystem is active. The high-pressure electric steering pump 23 is activated, the centering solenoid valve 29 and the proportional directional valve 26 are de-energized, and the valve cores of both the centering solenoid valve 29 and the proportional directional valve 26 are positioned as follows: Figure 5 The initial position is shown. The steering gear 11 drives the front wheels to rotate via the rocker arm 12, tie rod 13, front trapezoidal mechanism 14, and front power steering cylinder 21. The low-pressure electric steering pump 25 is not working; the centering part of the centering power steering cylinder 22 is working, that is, hydraulic oil enters the third working port A2 and the fourth working port B2 of the centering power steering cylinder 22 through the oil circuit containing the high-pressure electric steering pump 23 and the centering solenoid valve 29, fixing the rear wheels in the center position. The hydraulic oil in the first working port A1 and the second working port A2 of the centering power steering cylinder 22 enters the power steering oil tank 24 through the proportional directional valve 26.

[0090] Front and rear reverse steering mode: Both the high-pressure electric steering pump 23 and the low-pressure electric steering pump 25 are working. The steering gear 11 receives pressurized oil from the high-pressure electric steering pump 23 to control the rotation of the front wheels. The centering solenoid valve 29 is energized, the centering assist cylinder 22 is unlocked, and the assist function of the centering assist cylinder 22 is activated. Under the command of the electronic control system 30, the proportional directional valve 26 connects the assist oil circuit of the centering assist cylinder 22. That is, hydraulic oil enters the first working port A1 and the second working port B1 of the centering assist cylinder 22 through the oil circuit where the low-pressure electric steering pump 25 and the proportional directional valve 26 are located. The centering assist cylinder 22 can then push the rear wheels to rotate in the opposite direction to the front wheels.

[0091] Front and rear group same-direction steering mode: The working principle is the same as the front and rear group opposite-direction steering mode. The only difference is that in the front and rear group same-direction steering mode, the centering assist cylinder 22 pushes the rear group wheels to rotate in the same direction as the front group wheels.

[0092] Rear group follow-up mode: The high-pressure electric steering pump 23 operates, and the steering gear 11 receives pressurized oil from the high-pressure electric steering pump 23, controlling the rotation of the front group wheels. The front group power steering subsystem operates, providing assistance for the rotation of the front group wheels. The centering solenoid valve 29 is energized, and the centering assist cylinder 22 is unlocked. However, the rear group power steering subsystem does not operate, and the low-pressure electric steering pump 25 does not operate. The rear group wheels rotate under the action of ground friction, in the opposite direction to the front group wheels. When the transmission is engaged in reverse gear, the rear group follow-up mode is exited, and the front and rear group reverse steering mode is entered.

[0093] Emergency Steering Mode: After receiving a failure message from the high-pressure electric steering pump 23, the electronic control system 30 activates the low-pressure electric steering pump 25. The steering gear 11 receives pressurized oil from the low-pressure electric steering pump 25, controlling the rotation of the front wheels. The front power steering subsystem operates, providing assistance for the rotation of the front wheels. At this time, the centering solenoid valve 29 and the centering section of the centering assist cylinder 22 operate, fixing the rear wheels in the center position. The proportional directional valve 26 is de-energized, and the hydraulic oil in the first working port A1 and the second working port A2 of the centering assist cylinder 22 enters the power steering oil reservoir 24 through the proportional directional valve 26.

[0094] In most operating conditions, the system employs a front-wheel steering mode and a rear-wheel follow-up mode, with only one high-voltage electric steering pump operating while the low-voltage electric steering pump remains inactive, thus saving energy. For electric vehicles, the battery system has a limited capacity; therefore, the electric steering system provided in this embodiment is more suitable for electric vehicles, thereby reducing power consumption and increasing the vehicle's range. The low-voltage electric steering pump provides power for rear-wheel steering and emergency front-wheel steering, improving equipment utilization.

[0095] In this embodiment, the steering mode can be selected in two ways: automatic and manual. Besides being automatically determined by the electronic control system, the driver can also select it manually.

[0096] Automatic mode: The vehicle controller obtains steering wheel angle signals, vehicle speed signals, touch screen status signals, transmission gear signals, and status signals of the high-pressure and low-pressure electric power steering pumps from the bus. Through steering control logic algorithms, it determines the steering mode and calculates the theoretical rear wheel angle based on the steering mode, driving the proportional solenoid valve to control the rear wheel angle via the centering assist cylinder. The vehicle controller simultaneously controls the centering solenoid valve and the low-pressure electric power steering pump.

[0097] Figure 6This is a flowchart of the judgment logic for automatically determining the steering mode provided in an embodiment of the present invention, such as... Figure 6 As shown, after system initialization, if the high-pressure electric power steering pump is detected to be in normal condition, the transmission gear is not in reverse gear, and the vehicle speed is greater than 20 km / h but less than 80 km / h, then the system will enter the front steering mode; if the high-pressure electric power steering pump is detected to be in abnormal condition, then the system will enter the emergency steering mode; if the transmission gear is detected to be in reverse gear, then the system will enter the front and rear reverse steering mode; if the vehicle speed is detected to be less than or equal to 20 km / h, then the system will enter the rear follow-up mode; if the vehicle speed is detected to be greater than or equal to 80 km / h, then the system will enter the front and rear same-direction steering mode.

[0098] It should be noted that the automatic judgment logic of the above modes is only an example and is not limited thereto. Other judgment logic may also be used in other implementations of this embodiment.

[0099] Manual selection mode: The driver sends a steering mode request signal to the bus via the touch screen. After receiving the signal from the bus, the vehicle controller evaluates it along with other signals and then issues an acceptance or rejection message. If the touch screen receives an acceptance signal, it changes the screen status to manual; if the touch screen receives a rejection signal, it displays a warning message on the screen.

[0100] It should be noted that in this embodiment, the driver can only manually select to enter the front group steering mode or the front and rear group reverse steering mode.

[0101] Figure 7 This is a flowchart illustrating the logic for manually selecting a steering mode according to an embodiment of the present invention. Figure 7 As shown, firstly, the driver selects between front steering mode and reverse steering mode via the touchscreen display based on the current driving conditions. When the system determines that the high-pressure power steering pump is functioning normally, the vehicle speed is less than or equal to 20 km / h, and the rear wheel angle is less than or equal to 3°, it enters the corresponding front steering mode or reverse steering mode based on the driver's selection. If the system determines that the high-pressure power steering pump is malfunctioning, the vehicle speed is greater than 20 km / h, or the rear wheel angle is greater than 3°, it issues a corresponding warning. Simultaneously, when the system determines that the high-pressure power steering pump is malfunctioning, it directly enters the automatic determination mode. After entering either front steering mode or reverse steering mode, if the vehicle speed becomes greater than 20 km / h, it also reverts to the automatic determination mode.

[0102] Figure 8 This is a flowchart of a control method for an electric steering device provided in an embodiment of the present invention, as shown below. Figure 8 As shown, this control method is applicable to the above-mentioned electric steering device, and the control method includes:

[0103] Step S801: Determine the vehicle's steering mode.

[0104] Step S802: Send corresponding control commands to the hydraulic power steering system according to the vehicle's steering mode to make the vehicle enter the corresponding steering mode.

[0105] The vehicle's steering modes include: front steering mode, front and rear opposite steering mode, front and rear same steering mode, rear follow-up mode, and emergency steering mode.

[0106] The specific working principle of the hydraulic power assist system can be found in the relevant descriptions of the above embodiments, and will not be repeated here.

[0107] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0108] This invention provides an electric steering device and its control method, comprising a steering mechanical system, a hydraulic power assist system, and an electronic control system. The steering mechanical system transmits the forces of the front power assist cylinder and the centering power assist cylinder to the front and rear wheels of a vehicle, respectively, to achieve steering of the front and rear wheels. The hydraulic power assist system controls the front power assist cylinder according to the input shaft angle of the steering gear, causing the front wheels to steer and providing steering assistance for the front wheel rotation. The electronic control system determines the vehicle's steering mode and sends corresponding control commands to the hydraulic power assist system based on the steering mode. This allows the hydraulic power assist system to control the centering power assist cylinder accordingly, causing the rear wheels to steer or center, thereby enabling the vehicle to enter the corresponding steering mode and meeting the steering needs of the vehicle under different driving conditions, thus ensuring the safety and stability of vehicle operation.

[0109] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0110] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0111] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. An electric steering device, characterized in that, This includes the steering mechanism system, hydraulic power steering system, and electronic control system; The hydraulic power steering system includes a front power steering cylinder and a centering power steering cylinder, which are connected to the steering mechanism system. The steering mechanism system transmits the force from the front power steering cylinder to the front wheels of the vehicle and the force from the centering power steering cylinder to the rear wheels of the vehicle. The steering mechanism system includes a steering gear, and the hydraulic power steering system controls the front power steering cylinder according to the input shaft angle of the steering gear, thereby steering the front wheels of the vehicle. The electronic control system is used to determine the vehicle's steering mode and send corresponding control commands to the hydraulic power steering system according to the vehicle's steering mode, so that the vehicle enters the corresponding steering mode; wherein, the vehicle's steering modes include: front group steering mode, front and rear group opposite steering mode, front and rear group same-direction steering mode, rear group follow-up mode, and emergency steering mode. The hydraulic power steering system is used to control the centering assist cylinder according to the control command, so that the rear wheels of the vehicle are steered or centered. The hydraulic power steering system includes a front power steering subsystem, a rear power steering subsystem, and a centering power steering subsystem. The front power steering control subsystem controls the front power steering cylinder according to the input shaft angle of the steering gear to change the rotation angle and direction of the front wheels, providing steering assistance for the rotation of the front wheels. The rear power steering control subsystem controls the centering power steering cylinder to change the rotation angle and direction of the rear wheels. The centering power steering subsystem controls the centering power steering cylinder to center the rear wheels of the vehicle. The front power steering subsystem includes a high-pressure electric power steering pump, a front power steering cylinder, and a power steering fluid reservoir. The inlet of the high-pressure electric power steering pump is connected to the power steering fluid reservoir, the outlet of the high-pressure electric power steering pump is connected to the inlet of the steering gear, the first working port of the steering gear is connected to the rod-side port of the front power steering cylinder, the rodless port of the front power steering cylinder is connected to the second working port of the steering gear, and the return port of the steering gear is connected to the power steering fluid reservoir. The inlet of the steering gear is connected to either the first or second working port depending on the direction of steering wheel rotation, and the return port of the steering gear is connected to either the second or first working port depending on the direction of steering wheel rotation. The rear power steering subsystem includes a low-pressure electric steering pump, a proportional directional valve, a centering assist cylinder, and a power steering fluid reservoir. The inlet of the low-pressure electric steering pump is connected to the power steering fluid reservoir, the outlet of the low-pressure electric steering pump is connected to the inlet of the proportional directional valve, the first working port of the proportional directional valve is connected to the first working port of the centering assist cylinder, the second working port of the centering assist cylinder is connected to the second working port of the proportional directional valve, and the outlet of the proportional directional valve is connected to the power steering fluid reservoir. The proportional directional valve is a three-position, four-way electro-hydraulic proportional composite control solenoid valve, equipped with an amplifier. The output of the amplifier is connected to the control terminal of the proportional directional valve, and the input of the amplifier is connected to the electronic control system.

2. The electric steering device according to claim 1, characterized in that, The centering assist subsystem includes a high-pressure electric steering pump, a low-pressure electric steering pump, a pressure reducing valve, a first check valve, an accumulator, a second check valve, a centering solenoid valve, an overflow valve, a centering assist cylinder, a power steering oil tank, and a third check valve. The oil inlet of the high-pressure electric steering pump and the oil inlet of the low-pressure electric steering pump are both connected to the power steering oil tank. The oil inlet of the third check valve is connected to the oil outlet of the low-pressure electric steering pump, and the oil outlet of the third check valve is connected to the oil outlet of the high-pressure electric steering pump. The inlet of the pressure reducing valve is connected to the outlet of the high-pressure electric power steering pump; the outlet of the pressure reducing valve is connected to the inlet of the first one-way valve; the outlet of the first one-way valve is connected to the inlet of the second one-way valve; the outlet of the second one-way valve is connected to the inlet of the centering solenoid valve; the drain port of the centering solenoid valve is connected to the power steering reservoir; the first working port of the centering solenoid valve is connected to the third and fourth working ports of the centering assist cylinder; the drain port of the centering assist cylinder is connected to the power steering reservoir; the inlet of the overflow valve is connected to the first working port of the centering solenoid valve; the outlet of the overflow valve is connected to the power steering reservoir; and the accumulator is connected between the first one-way valve and the second one-way valve. The high-pressure electric steering pump is powered by a high-pressure power supply system, and the low-pressure electric steering pump is powered by a low-pressure power supply system.

3. The electric steering device according to claim 1, characterized in that, The steering mechanism system also includes a rocker arm, a tie rod, a front trapezoidal mechanism, and a rear trapezoidal mechanism; The rocker arm is connected to the steering gear. One end of the straight tie rod is connected to the end of the rocker arm away from the steering gear, and the other end of the straight tie rod is connected to the front trapezoidal mechanism. The two ends of the front trapezoidal mechanism are connected to the front wheels of the vehicle, and the straight tie rod drives the front wheels of the vehicle to rotate. The two ends of the rear trapezoidal mechanism are connected to the rear wheels of the vehicle.

4. The electric steering device according to claim 3, characterized in that, The front trapezoidal mechanism includes a first trapezoidal arm, a second trapezoidal arm, and a first horizontal tie rod; The first trapezoidal arm and the second trapezoidal arm are respectively connected to the two ends of the first crossbar, and the end of the first trapezoidal arm away from the first crossbar and the end of the second trapezoidal arm away from the first crossbar are respectively connected to the two front wheels of the vehicle.

5. The electric steering device according to claim 3, characterized in that, The rear trapezoidal mechanism includes a third trapezoidal arm, a fourth trapezoidal arm, and a second horizontal tie rod; The third trapezoidal arm and the fourth trapezoidal arm are respectively connected to the two ends of the second crossbar, and the end of the third trapezoidal arm away from the second crossbar and the end of the fourth trapezoidal arm away from the second crossbar are respectively connected to the two rear wheels of the vehicle.

6. The electric steering device according to claim 1, characterized in that, The electronic control system is also used for: Obtain vehicle status information, which includes at least front wheel steering angle information, rear wheel steering angle information, vehicle speed information, and transmission gear information; The vehicle's steering mode is determined based on the vehicle's status information.

7. A control method for an electric steering device, characterized in that, The control method, applicable to the electric steering system as described in any one of claims 1 to 6, comprises: Determine the vehicle's steering mode; According to the vehicle's steering mode, a corresponding control command is sent to the hydraulic power steering system to cause the vehicle to enter the corresponding steering mode. The vehicle's steering modes include: front group steering mode, front and rear group opposite steering mode, front and rear group same-direction steering mode, rear group follow-up mode, and emergency steering mode.

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