CN113492906B - Hydraulic steering system and control method and device thereof - Google Patents
Hydraulic steering system and control method and device thereof Download PDFInfo
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- CN113492906B CN113492906B CN202010260770.5A CN202010260770A CN113492906B CN 113492906 B CN113492906 B CN 113492906B CN 202010260770 A CN202010260770 A CN 202010260770A CN 113492906 B CN113492906 B CN 113492906B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
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Abstract
The invention relates to a hydraulic steering system and a control method and device thereof, belonging to the technical field of vehicle steering control. The control method comprises the following steps: acquiring steering wheel torque, duration of the steering wheel torque, steering wheel turning angle and displacement of a piston in a hydraulic cylinder; if the steering wheel torque is smaller than the set torque lower limit or the duration of any steering wheel torque is smaller than the set duration lower limit, the vehicle does not have steering action; judging whether the steering wheel is in the zero position range of the steering wheel according to the steering wheel angle, and judging whether the piston is in the zero position range of the piston according to the displacement of the piston in the hydraulic cylinder; if the hydraulic flow control hydraulic cylinder is not in the zero position range, the steering wheel is driven to return to the zero position range of the steering wheel through the return positive motor, and the piston in the hydraulic cylinder is controlled to be in the piston zero position range through the control system hydraulic flow to drive the vehicle to return to the positive position. According to the invention, the vehicle is controlled to automatically return to the right by the hydraulic steering system through the acquired information, the driver does not need to manually return to the right, and the working intensity of the driver is reduced.
Description
Technical Field
The invention relates to a hydraulic steering system and a control method and device thereof, and belongs to the technical field of vehicle steering control.
Background
During the driving process of the automobile, the driving direction is often required to be changed or a stable straight driving direction is required to be maintained. The change of the driving direction of the wheeled vehicle is realized by a driver through a set of special mechanisms to enable wheels on an automobile steering axle to deflect a certain angle relative to the longitudinal axis of the automobile. When the automobile runs in a straight line, the steering wheel deviates from the straight line running direction under the action of the lateral interference force of the road surface, and at the moment, a driver can operate the steering mechanism to restore the automobile to the correct straight line running direction. The set of specially designed mechanisms on the automobile is called an automobile steering system.
The automobile steering system can be divided into a mechanical steering system and a power steering system according to different steering energy sources. The mechanical steering system is a steering system taking the physical power of a driver as a steering energy source, wherein all force transmission pieces consist of mechanical elements; the power steering system is a steering system with a mechanical steering system and a power steering boosting device acting together, and is a servo steering system, when a vehicle needs to be steered, a driver only needs to provide a small part of energy, and most of the energy is provided by an engine or a motor.
The conventional steering system is a novel hydraulic steering system, and the system consists of an Electronic Control Unit (ECU), a torque sensor, an electric steering oil pump and an electronic control hydraulic valve bank, wherein the requirement of a driver for rotating a steering wheel can be collected by the torque sensor, the ECU controls the electric steering oil pump to provide steering power for the hydraulic system through torque information collected by the torque sensor, and the electronic control hydraulic valve bank is controlled to realize quantitative and directional control of hydraulic oil, so that the control of vehicles, steering and straight-line running is finally realized. Although the steering system reduces the working intensity of a driver when the vehicle steers, the working intensity of the driver is not reduced when the vehicle is steered, the existing vehicle aligning mode mainly depends on aligning torque generated by a kingpin inclination angle and a kingpin caster angle, but the aligning torque only provides a small part of aligning energy, and on a road with poor road surface conditions, the main energy source for aligning depends on manual aligning of the driver, so that the labor intensity of the driver is overlarge, and the driver is easy to fatigue.
Disclosure of Invention
The application aims to provide a control method of a hydraulic steering system, which is used for solving the problems of high labor intensity and easy fatigue of a driver caused by the existing aligning mode; meanwhile, a control device of the hydraulic steering system is also provided, so as to solve the problems of high labor intensity and easy fatigue of a driver caused by the existing aligning mode; meanwhile, a hydraulic steering system is also provided for solving the problems that the existing aligning mode causes the driver to have high labor intensity and be easy to fatigue.
In order to achieve the above object, the present application provides a technical solution of a control method of a hydraulic steering system, including the steps of:
1) Acquiring steering wheel torque, duration of the steering wheel torque, steering wheel rotation angle and displacement of a piston in a hydraulic cylinder;
2) Judging whether the vehicle has steering action; the judgment condition of the vehicle non-steering action is as follows: the steering wheel torque is less than a set torque lower limit, or the duration of any steering wheel torque is less than a set duration lower limit;
3) If the vehicle does not have steering action, judging whether the steering wheel is in the zero position range of the steering wheel according to the steering angle of the steering wheel, and judging whether the piston is in the zero position range of the piston according to the displacement of the piston in the hydraulic cylinder; the steering wheel zero position range is a first set range deviating from the steering wheel by a steering angle of 0; the piston zero position range is a third set range with the offset displacement of 0;
4) If the steering wheel angle is not in the steering wheel zero position range and the displacement of the piston in the hydraulic cylinder is not in the piston zero position range, the steering wheel is driven to return to the steering wheel zero position range through the return positive motor, and the piston in the hydraulic cylinder is controlled to be in the piston zero position range through the hydraulic flow of the control system, so that the vehicle is driven to return to the positive position.
In addition, the present application also provides a technical solution of a control device of a hydraulic steering system, which includes a processor, a memory, and a computer program stored in the memory and operable on the processor, wherein the processor implements the technical solution of the control method of the hydraulic steering system when executing the computer program.
The technical scheme of the control method and the control device of the hydraulic steering system has the beneficial effects that: the invention judges whether the vehicle has the steering action or not through the steering wheel torque and the duration time of the steering wheel torque, if the vehicle does not have the steering action, the vehicle needs to be corrected, at the moment, whether the steering wheel angle and the piston displacement are both in the zero position range or not is judged, if the steering wheel angle and the piston displacement are both larger due to the fact that the steering wheel angle and the piston displacement are not in the zero position range, the steering wheel and the piston are controlled to return to the zero position range.
Further, in the control method and apparatus of the hydraulic steering system, in order to ensure that the vehicle travels straight, if the steering wheel angle is in the steering wheel zero position range and is not in the steering wheel middle travel range, and the displacement of the piston in the hydraulic cylinder is in the piston zero position range and is not in the piston middle travel range, the steering wheel is driven to return to the steering wheel middle travel range through the return positive motor, the piston in the hydraulic cylinder is controlled to be in the piston middle travel range through the control system hydraulic flow, so as to ensure that the vehicle travels straight, and the steering wheel middle travel range is a second set range deviating from the steering wheel angle by 0; the middle running range of the piston is a fourth set range with the offset displacement of 0; the second setting range is smaller than the first setting range; the fourth setting range is smaller than the third setting range.
Further, in the method and the device for controlling the hydraulic steering system, in order to avoid failure of the hydraulic steering system due to overhigh temperature, the temperature of the hydraulic cylinder is also obtained in the step 1), if the temperature is greater than or equal to a first temperature threshold value, the power limit output of the hydraulic steering system is controlled, and if the temperature is greater than or equal to a second temperature threshold value, the hydraulic steering system is controlled to stop, wherein the second temperature threshold value is greater than the first temperature threshold value.
Further, in the control method and apparatus of the hydraulic steering system, in order to reduce the residual angle of the return of the vehicle, the closed-loop control is performed based on the feedback amount of the displacement of the piston in the hydraulic cylinder and the closed-loop control is performed based on the feedback amount of the steering wheel angle while the vehicle is being driven to return to the original position.
Further, in the control method and device of the hydraulic steering system, in order to realize the steering of the vehicle, if the steering wheel torque is greater than or equal to the set lower torque limit and the duration of the steering wheel torque is greater than or equal to the set lower duration limit, the vehicle has a steering action, the steering wheel turning speed and the vehicle speed are obtained, and the hydraulic flow of the system is controlled according to the steering wheel turning angle, the steering wheel turning speed and the vehicle speed, so that the displacement of the piston in the hydraulic cylinder is increased, and the steering of the vehicle is realized.
Furthermore, in the control method and the control device of the hydraulic steering system, in order to improve the accuracy of vehicle steering, the hydraulic flow in the hydraulic cylinder is detected in real time during the vehicle steering process, and closed-loop control is performed according to the feedback quantity of the hydraulic flow in the hydraulic cylinder.
In addition, the present application further provides a technical solution of a hydraulic steering system, the system includes a hydraulic oil circulation pipeline composed of a steering oil tank, an electric steering oil pump, an electric control steering hydraulic valve set and a hydraulic cylinder, and is used for driving wheels to steer, and further includes a return positive motor for driving a steering wheel to return to positive, a corner sensor for collecting a steering wheel corner, a torque sensor for collecting a steering wheel torque, a displacement sensor for collecting a displacement of a piston in the hydraulic cylinder, and a control device, an input end of the control device is connected to the corner sensor, the torque sensor and the displacement sensor, an output end of the control device is connected to the electric steering oil pump, the electric control steering hydraulic valve set and the return positive motor, the control device includes a processor, a memory and a computer program which is stored in the memory and can run on the processor, and the processor implements the following steps when executing the computer program:
1) Acquiring steering wheel torque, duration of the steering wheel torque, steering wheel turning angle and displacement of a piston in a hydraulic cylinder;
2) Judging whether the vehicle has steering action; the judgment condition of the vehicle non-steering action is as follows: the steering wheel torque is less than a set torque lower limit, or the duration of any steering wheel torque is less than a set duration lower limit;
3) If the vehicle does not have steering action, judging whether the steering wheel is in the zero position range of the steering wheel according to the steering wheel angle, and judging whether the piston is in the zero position range of the piston according to the displacement of the piston in the hydraulic cylinder; the steering wheel zero position range is a first set range deviating from the steering wheel by a steering angle of 0; the piston zero position range is a third set range with the offset displacement of 0;
4) If the steering wheel angle is not in the steering wheel zero position range and the displacement of the piston in the hydraulic cylinder is not in the piston zero position range, the steering wheel is driven to return to the steering wheel zero position range through the return positive motor, and the piston in the hydraulic cylinder is controlled to be in the piston zero position range through the hydraulic flow of the control system, so that the vehicle is driven to return to the positive position.
The technical scheme of the hydraulic steering system has the beneficial effects that: the invention judges whether the vehicle has steering action or not through the steering wheel torque acquired by the torque sensor and the duration of the steering wheel torque, if the vehicle does not have the steering action, the vehicle needs to return to the positive position, at the moment, the steering wheel angle and the piston displacement are judged to be in the zero position range through the corner sensor and the displacement sensor, if the steering wheel angle and the piston displacement are not in the zero position range, the steering wheel returns to the zero position range through controlling the return-to-positive motor, and the piston returns to the zero position range through controlling the hydraulic oil circulation pipeline.
Further, in order to ensure that the vehicle runs in a straight line, if the steering wheel corner is in the steering wheel zero position range and is not in the steering wheel middle running range, and the displacement of the piston in the hydraulic cylinder is in the piston zero position range and is not in the piston middle running range, the steering wheel is driven to return to the steering wheel middle running range through the positive returning motor, the piston in the hydraulic cylinder is controlled to be in the piston middle running range through the control system hydraulic flow, and the vehicle is ensured to run in a straight line, wherein the steering wheel middle running range is a second set range deviating from the steering wheel corner by 0; the middle running range of the piston is a fourth set range with the offset displacement of 0; the second setting range is smaller than the first setting range; the fourth setting range is smaller than the third setting range.
Further, in order to avoid failure of the hydraulic steering system caused by overhigh temperature, the temperature of the hydraulic cylinder is also obtained in the step 1), if the temperature is larger than or equal to a first temperature threshold value, the power limit output of the hydraulic steering system is controlled, and if the temperature is larger than or equal to a second temperature threshold value, the hydraulic steering system is controlled to be stopped, wherein the second temperature threshold value is larger than the first temperature threshold value.
Furthermore, in order to reduce the residual angle of the vehicle return, in the process of driving the vehicle to return, closed-loop control is carried out according to the feedback quantity of the displacement of the piston in the hydraulic cylinder, and closed-loop control is carried out according to the feedback quantity of the steering wheel angle.
Furthermore, in order to realize the steering of the vehicle, the hydraulic steering system also comprises a vehicle speed sensor for collecting the vehicle speed, the steering wheel turning speed is calculated according to the steering wheel turning angle collected by the turning angle sensor, if the steering wheel torque is larger than or equal to the set torque lower limit and the duration of the steering wheel torque is larger than or equal to the set duration lower limit, the vehicle has the steering action, and the hydraulic flow of the system is controlled according to the steering wheel turning angle, the steering wheel turning speed and the vehicle speed, so that the displacement of a piston in the hydraulic cylinder is increased, and the steering of the vehicle is realized.
Furthermore, in order to improve the accuracy of vehicle steering, the hydraulic steering system also comprises a flowmeter for detecting the hydraulic flow in the hydraulic cylinder, and during the vehicle steering, closed-loop control is performed according to the feedback quantity of the hydraulic flow in the hydraulic cylinder.
Drawings
FIG. 1 is a block diagram of a hydraulic steering system of the present invention;
FIG. 2 is a schematic structural view of a control device of the hydraulic steering system of the present invention;
FIG. 3 is a return schematic of the hydraulic steering system of the present invention;
FIG. 4 is a left hand schematic view of the hydraulic steering system of the present invention;
fig. 5 is a control flowchart of embodiment 1 of the present invention;
fig. 6 is a control flowchart of embodiment 2 of the present invention;
in the figure: the system comprises a front right wheel 1, a front left wheel 2, a hydraulic cylinder 3, an acquisition module 4, a steering oil tank 5, an electric steering oil pump 6, a torque angle sensor 7, a back-positive motor 8, a steering wheel 9, a flow meter 10, an electric control steering hydraulic valve bank 11, an electric steering oil pump ECU12, a back-positive motor ECU13 and a control device 14.
Detailed Description
Hydraulic steering system embodiment:
as shown in fig. 1, the hydraulic steering system includes a hydraulic cylinder 3, a collection module 4, a steering oil tank 5, an electric steering oil pump 6, a torque angle sensor 7, a return motor 8, a steering wheel 9, a flow meter 10, an electric steering hydraulic valve bank 11, an electric steering oil pump ECU12, a return motor ECU13, and a control device 14.
The hydraulic cylinder 3 is a double-acting hydraulic cylinder, and comprises a cylinder body, a piston rod and the like, the piston rod in the hydraulic cylinder 3 is connected with the right front wheel 1 and the left front wheel 2 through a transverse pull rod, a ball joint and a steering knuckle, the hydraulic cylinder 3 can convert hydraulic energy into mechanical energy, and a kingpin of the right front wheel 1 and the left front wheel 2 is driven to rotate through the movement of the piston position;
the steering oil tank 5 is used for storing and filtering hydraulic oil;
the electric steering oil pump 6 consists of a steering oil pump and a motor, converts electric energy into mechanical energy to drive the steering oil pump to rotate, and the steering oil pump converts the mechanical energy into hydraulic energy to provide power for the whole hydraulic steering system and drive hydraulic oil to flow; the electric steering oil pump 6 is provided with an electric steering oil pump ECU12;
the electric control steering hydraulic valve group 11 comprises a valve block, a pressure compensator, a proportional reversing valve, a balance valve, a shuttle valve, an electromagnetic ball valve, an overflow valve and the like, and is used for realizing the quantitative and directional control of hydraulic oil;
the hydraulic steering system comprises a steering oil tank 5, an electric steering oil pump 6, an electric control steering hydraulic valve group 11 and a hydraulic cylinder 3 which are circularly connected, wherein the electric steering oil pump 6 and the steering oil tank 5 are respectively provided with two oil inlets and two oil outlets, the electric control steering hydraulic valve group 11 is provided with one oil inlet, two oil outlets and one oil return port, the hydraulic cylinder 3 is provided with two oil ports, the oil inlet of the electric steering oil pump 6 is connected with the oil outlet of the steering oil tank 5 through an oil pipe, the oil outlet of the electric steering oil pump 6 is connected with the oil inlet of the electric control steering hydraulic valve group 11 through a pipeline, the oil return port of the electric control steering hydraulic valve group 11 is connected with the oil inlet of the steering oil tank 5 through a pipeline, the two oil outlets of the electric control steering hydraulic valve group 11 are respectively connected with the two oil ports of the hydraulic cylinder 3 through pipelines to form a steering pipeline for circulating hydraulic oil, the movement of a piston in the hydraulic cylinder 3 is pushed, and the steering pipeline comprises an oil suction pipe, a high-pressure pipe and an oil return pipe; the electric steering oil pump 6 and the electric control steering hydraulic valve group 11 are connected with an electric steering oil pump ECU12, and are connected with a control device 14 through the electric steering oil pump ECU12 so as to control the working states of the electric steering oil pump 6 and the electric control steering hydraulic valve group 11;
the acquisition module 4 comprises a displacement sensor and a temperature sensor, wherein the displacement sensor is a pressure type position sensor, is connected with the hydraulic cylinder 3, is connected with the control device 14 through a CAN bus, and is used for acquiring the displacement of a piston in the hydraulic cylinder 3 and sending the displacement to the control device 14; the temperature sensor is arranged on the outer side of the hydraulic cylinder 3, is connected with the control device 14 through a CAN bus, and is used for acquiring the temperature of the hydraulic cylinder 3 and sending the temperature to the control device 14;
the torque angle sensor 7 is an integrated sensor capable of acquiring torque and a turning angle, is mounted on the steering wheel 9, is connected with the control device 14 through a CAN bus, and is used for acquiring the torque and the turning angle of the steering wheel 9 and sending the torque and the turning angle to the control device 14;
the flowmeter 10 is arranged on a connecting pipeline between the hydraulic cylinder 3 and the electric control steering hydraulic valve group 11 and is used for detecting the hydraulic flow of the hydraulic cylinder 3;
the positive electricity returning machine 8 consists of a brushless direct current motor and a worm gear reducer, is arranged on a steering column, is connected with a steering wheel 9, is provided with a positive electricity returning machine ECU13 and is connected with the positive electricity returning machine ECU13, and the positive electricity returning machine ECU13 is connected with a control device 14; a control device 14 for receiving a command converted by the electricity return motor ECU13 and outputting a return torque to drive the steering wheel 9 to return (i.e., to drive the steering wheel 9 to a rotation angle of approximately 0);
the control device 14 is a core component of the entire hydraulic steering system, and has a structure as shown in fig. 2, and includes a processor, a memory, and a computer program stored in the memory and executable on the processor, and the processor implements a control method of the hydraulic steering system when executing the computer program. The specific control device 14 is a Vehicle Control Unit (VCU), and as another embodiment, it may also be a controller that is added separately and can implement the method of the embodiment.
The main idea of the control method is to control the vehicle to actively return to the right, the control device 14 judges whether the vehicle has a steering action through the torque information collected by the torque angle sensor 7 and the duration of the torque, and the control device controls the vehicle to return to the right through the hydraulic steering system under the condition that the vehicle does not have the steering action.
Specifically, as shown in fig. 3, when the vehicle is turning left, the vehicle is aligned according to the alignment control method shown in fig. 5:
1) The torque angle sensor 7 collects the torque and the steering wheel angle, the displacement sensor collects the displacement of the piston and sends the collected information to the VCU, and the VCU judges that the torque of the steering wheel is less than a set lower torque limit M 0 Or the duration of any steering wheel torque is less than the set lower limit t 0 The vehicle is not steered.
2) After the VCU judges that the vehicle does not have steering action, then the VCU judges that the steering wheel corner is not in the steering wheel zero position range and the displacement of the piston is not in the piston zero position range;
the steering wheel null range is a set range (first set range) in which the system recognizes that the steering wheel 9 has returned to the null position and does not need to return to the null position, but the absolute steering wheel angle is not 0, but is deviated from the steering wheel angle by 0, and the magnitude of the steering wheel angle is < θ 0 The piston zero position range is a setting range (third setting range) with the displacement of 0, wherein the displacement is less than S 0 ；
The steering wheel angle is not in the zero position range of the steering wheel, namely the steering wheel angle is not less than or equal to theta 0 The displacement of the piston is not in the zero position range of the piston, namely the displacement is more than or equal to S 0 。
3) A VCU issues a piston return instruction which is issued to an electric steering oil pump 6 and an electric steering hydraulic valve group 11 through an electric steering oil pump ECU12, and the electric steering oil pump ECU12 outputs a reverse current I 3 To the electric control steering hydraulic valve set 11, and the hydraulic flow Q is reversed through the control system 3 The hydraulic oil flows into the upper side of the hydraulic cylinder 3 (the flow direction of the hydraulic oil is shown by an arrow in fig. 3), so that a piston in the hydraulic cylinder 3 moves downwards, the piston in the hydraulic cylinder 3 is controlled to return to a piston zero position range, and the right front wheel 1 and the left front wheel 2 are driven to return to a positive position;
meanwhile, the VCU issues a returning positive command of the returning positive motor 8, the command is issued to the returning positive motor 8 through the returning positive motor ECU13, and the returning positive motor ECU13 outputs a reverse current I 4 When the steering wheel returns to the positive motor 8, the steering wheel 9 is driven to return to the zero position range of the steering wheel by the positive returning motor 8, namely, the steering wheel 9 is driven to return to the positive position;
in the vehicle aligning process, in order to avoid a vehicle aligning residual angle, a displacement sensor sends collected displacement to a VCU as feedback quantity, the VCU performs closed-loop control on piston displacement after judgment, a steering wheel rotating angle collected by a torque angle sensor 7 is sent to the VCU as feedback quantity, and the VCU performs closed-loop control on the steering wheel rotating angle after judgment;
while the vehicle is returningIn the process, the temperature sensor collects the temperature of the hydraulic cylinder 3 in real time and sends the collected temperature to the VCU, and the VCU judges that the temperature is more than or equal to the first temperature threshold value 80 percent T 0 If the VCU controls the power-limiting output of the hydraulic steering system, and the VCU judges that the temperature is more than or equal to a second temperature threshold value T 0 Then the VCU controls the hydraulic steering system to stop.
In the present embodiment, the temperature sensor is disposed outside the hydraulic cylinder 3 to measure the temperature of the outer surface of the hydraulic cylinder 3 for easy installation, but the temperature sensor may be disposed inside the hydraulic cylinder 3 to measure the temperature of the hydraulic oil in the hydraulic cylinder 3 as another embodiment, which is not limited to this embodiment.
Moreover, if the vehicle alignment accuracy can be ensured in the alignment process, closed-loop control according to the flowmeter 10 is not needed; meanwhile, if the temperature that the hydraulic system can bear is large enough, the temperature sensor is not needed to be arranged when the temperature is ensured to be in a normal range.
In the above embodiments, the first temperature threshold = the second temperature threshold T 0 * As another embodiment, the first temperature threshold and the second temperature threshold may be set as needed, and it is sufficient to ensure that the second temperature threshold > the first temperature threshold.
The steering control process shown in fig. 5 is described taking the left steering of the vehicle shown in fig. 4 as an example:
1) The torque angle sensor 7 collects the torque and the steering wheel angle, the displacement sensor collects the displacement of the piston and sends the collected information to the VCU, and the VCU judges that the torque of the steering wheel is larger than or equal to a set lower torque limit M 0 And the duration of the torque of the steering wheel is more than or equal to the set duration lower limit t 0 The vehicle has a left-hand steering action.
2) After the VCU judges that the vehicle has left steering action, the steering wheel turning speed and the vehicle speed are obtained (the steering wheel turning speed is calculated according to the steering wheel turning angle collected by the torque angle sensor 7, the vehicle speed can be obtained by a vehicle speed sensor, and is not shown in the figure), the obtained steering wheel turning speed and the vehicle speed are sent to the VCU, the VCU judges a corresponding control curve according to the steering wheel turning angle, the steering wheel turning speed and the vehicle speed, and the electric steering oil pump 6 and the electric steering hydraulic valve group 11 are controlled to work through the electric steering oil pump ECU12;
input current I of electric steering oil pump ECU12 1 To the electric control steering hydraulic valve group 11, the opening direction and the size of the electric control steering hydraulic valve group 11 are controlled, and a certain flow Q is controlled 1 The hydraulic oil enters the lower side of the hydraulic cylinder 3, and the hydraulic oil flows in the direction shown in fig. 4 (the direction of the arrow in fig. 4 is the flow direction of the hydraulic oil), so that the piston in the hydraulic cylinder 3 moves upward, and the right front wheel 1 and the left front wheel 2 are driven to rotate leftward, and the steering operation is completed.
In the step, power-assisted curves at different speeds are stored in the VCU, so that large flow is provided when the VCU is driven at the original place and at the low speed, the power is increased, small flow is provided when the VCU is driven at the medium and high speeds, the power is reduced, and the low-speed light and high-speed sinking stability can be realized; the flow of the hydraulic oil is related to the turning speed, the flow is increased under the condition of larger turning speed, insufficient power assistance during rapid steering is avoided, and the emergency avoidance performance of the vehicle is improved.
3) In the process that the right front wheel 1 and the left front wheel 2 rotate leftwards, the flow meter 10 collects the flow of hydraulic oil flowing into the hydraulic cylinder 3 in real time and sends the collected information to the VCU, the VCU judges whether flow compensation is needed or not after logic calculation, and if the flow compensation is needed, the electric steering oil pump ECU12 inputs current I 2 To the electric control steering hydraulic valve set 11 and to the electric control steering hydraulic valve set 11 to compensate the flow Q 2 And the closed-loop control is realized to the hydraulic cylinder 3.
Meanwhile, during the process that the right front wheel 1 and the left front wheel 2 rotate to the left, the temperature sensor detects the temperature of the hydraulic cylinder 3 in real time, if the temperature is more than or equal to the first temperature threshold value 80% 0 If the temperature is larger than or equal to a second temperature threshold value T, the VCU controls the power-limiting output of the hydraulic steering system 0 And the VCU controls the hydraulic steering system to stop.
The steering control of the vehicle for turning right is the same as the steering control principle of the vehicle for turning left, and the principle of the vehicle for turning right is the same as the principle of turning left, which is not described herein.
The invention can judge whether the vehicle has the steering action or not based on the steering wheel torque and the duration of the steering wheel torque, drives the steering wheel 9 to return through the return motor 8 under the condition that the vehicle has no steering action, and drives the wheel to return through controlling the hydraulic flow, thereby reducing the working intensity of a driver.
The embodiment of the control device of the hydraulic steering system comprises:
the control device of the hydraulic steering system proposed in the present embodiment, as shown in fig. 2, includes a processor, a memory, and a computer program stored in the memory and executable on the processor, and the processor implements a control method of the hydraulic steering system when executing the computer program.
The specific implementation process and effect of the control method of the hydraulic steering system are described in the above embodiment of the hydraulic steering system, and are not described herein again.
That is, the method in the above hydraulic steering system embodiments should be understood that the flow of the control method of the hydraulic steering system may be implemented by computer program instructions. These computer program instructions may be provided to a processor (e.g., a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus), such that the instructions, which execute via the processor, create means for implementing the functions specified in the method flow.
The processor referred to in this embodiment refers to a processing device such as a microprocessor MCU or a programmable logic device FPGA;
the memory of the present embodiment is used to store computer program instructions for implementing a method for controlling a hydraulic steering system, and includes physical means for storing information, and typically, the information is digitized and stored in a medium using an electrical, magnetic, or optical system. For example: various memories for storing information by using an electric energy mode, such as RAM, ROM and the like; various memories for storing information by magnetic energy, such as hard disk, floppy disk, magnetic tape, magnetic core memory, bubble memory, and U disk; various types of memory, CD or DVD, that store information optically. Of course, there are other ways of memory, such as quantum memory, graphene memory, and so forth.
The control device of the hydraulic steering system, which is composed of the memory storing the computer program instructions for realizing the control method of the hydraulic steering system and the processor, is realized by the processor executing the corresponding program instructions in the computer, and the computer can be realized by a windows operating system, a linux system or other systems, for example, an android and an iOS system programming language in an intelligent terminal, a processing logic realization based on a quantum computer, and the like.
As other embodiments, the control device of the hydraulic steering system may further include other processing hardware, such as a database, a multi-level buffer, a GPU, and the like, and the present invention does not specifically limit the structure of the control device of the hydraulic steering system.
The embodiment of the control method of the hydraulic steering system comprises the following steps:
the implementation process and the effect of the control method of the hydraulic steering system proposed in this embodiment have been described in the above-mentioned embodiments of the hydraulic steering system, and are not described herein again.
Hydraulic steering system embodiment:
the hardware configuration and connection relationship of the hydraulic steering system in this embodiment are the same as those of the hydraulic steering system in embodiment 1, and details thereof are not described here. The control method in embodiment 1 is a return control method for returning the steering wheel 9 and the piston to the null range in which the magnitude of the steering wheel angle < θ 0 The magnitude of the displacement is less than S 0 The steering wheel angle is not an absolute zero position, and the vehicle is very difficult to keep running in a straight line, and the driver is required to continuously adjust the steering wheel 9 angle according to road conditions, so that the straight line running control is increased, and the working intensity of the driver is further reduced.
The steering control and the return control have already been described in the embodiment of the hydraulic steering system in embodiment 1, and will not be described in detail here.
The embodiment is in the steering wheel zero position range and the displacement zero position rangeFinely dividing the steering wheel zero position range into a steering wheel middle driving range and a non-steering wheel middle driving range, dividing the displacement zero position range into a displacement middle driving range and a non-displacement middle driving range, and selecting a steering wheel corner alpha as a critical steering wheel corner, wherein alpha is more than theta 0 (ii) a Selecting displacement L as critical displacement, L is less than S 0 . Specifically, the magnitude of the steering wheel angle is more than alpha and less than theta 0 The steering wheel is not in the middle driving range of the steering wheel, and the steering angle alpha is not more than alpha and is in the middle driving range of the steering wheel; l < magnitude of displacement < S 0 The displacement is equal to or less than L, and the displacement is the middle driving range.
The middle driving range of the steering wheel is a second set range deviating from the steering wheel by the turning angle of 0, and the middle driving range of the steering wheel is smaller than the zero position range of the steering wheel, namely the second set range is smaller than the first set range; the piston middle driving range is a fourth setting range with the offset displacement of 0, and the displacement middle driving range is smaller than the displacement zero position range, namely the fourth setting range is smaller than the third setting range.
Specifically, the control process of the straight-line driving is shown in fig. 6, and includes the following steps:
1) The torque angle sensor 7 collects the torque and the steering wheel angle, the displacement sensor collects the displacement of the piston and sends the collected information to the VCU, and the VCU judges that the torque of the steering wheel is less than a set lower torque limit M 0 Or the duration of any steering wheel torque is less than the set lower limit t 0 The vehicle is not steered.
2) After VCU judges that the vehicle has no steering action, then it judges that alpha is less than steering wheel angle and theta is less than 0 The steering wheel is not required to be subjected to aligning control, but is in a non-steering wheel middle driving range; l < magnitude of displacement < S 0 The return control is not required, but is in the non-displacement intermediate travel range.
3) In order to ensure the stability of straight line driving, the VCU issues an instruction to ensure that the size of the turning angle of the steering wheel is less than or equal to alpha; so that the size of the displacement is less than or equal to L; the principle of controlling the magnitude of the steering wheel angle is the same as the steering wheel aligning principle, and the principle of controlling the magnitude of the displacement is the same as the wheel aligning principle, which is not described in detail herein.
Of course, if the steering wheel angle is directly judged to be in the middle driving range in the step 2), and the displacement is in the middle driving range, the vehicle is indicated to be in straight line driving, the phenomenon of deviation cannot occur, and adjustment is not needed.
In embodiment 1, the straight-line running control is added, so that the phenomena of road surface jolt, abnormal impact and deviation caused by inaccurate four-wheel positioning parameters can be avoided, and the straight-line running performance of the vehicle is improved.
The embodiment of the control device of the hydraulic steering system comprises:
as shown in fig. 2, the control device of the hydraulic steering system according to the present embodiment includes a processor, a memory, and a computer program stored in the memory and executable on the processor, and the processor implements a control method of the hydraulic steering system when executing the computer program.
The hardware configuration of the control device of the hydraulic steering system of the present embodiment is the same as that of the control device of embodiment 1, and details thereof are not described herein; the specific implementation process and effect of the control method implemented by the control device are described in the above embodiment of the hydraulic steering system, and are not described herein again.
The embodiment of the control method of the hydraulic steering system comprises the following steps:
the implementation process and the effect of the control method of the hydraulic steering system proposed in this embodiment have been described in the above-mentioned embodiments of the hydraulic steering system, and are not described herein again.
Claims (9)
1. A control method of a hydraulic steering system, characterized by comprising the steps of:
1) Acquiring steering wheel torque, duration of the steering wheel torque, steering wheel turning angle and displacement of a piston in a hydraulic cylinder;
2) Judging whether the vehicle has steering action; the judgment condition of the vehicle non-steering action is as follows: the steering wheel torque is less than a set torque lower limit, or the duration of any steering wheel torque is less than a set duration lower limit;
3) If the vehicle does not have steering action, judging whether the steering wheel is in the zero position range of the steering wheel according to the steering angle of the steering wheel, and judging whether the piston is in the zero position range of the piston according to the displacement of the piston in the hydraulic cylinder; the steering wheel zero position range is a first set range deviating from the steering wheel by a steering angle of 0; the piston zero position range is a third set range with the offset displacement of 0;
4) If the steering wheel angle is not in the steering wheel zero position range and the displacement of the piston in the hydraulic cylinder is not in the piston zero position range, the steering wheel is driven to return to the steering wheel zero position range through the return positive motor, the piston in the hydraulic cylinder is controlled to be in the piston zero position range through the control system hydraulic flow, and the vehicle is driven to return to the positive position;
if the steering wheel corner is in the steering wheel zero position range and is not in the steering wheel middle driving range, and the displacement of the piston in the hydraulic cylinder is in the piston zero position range and is not in the piston middle driving range, the steering wheel is driven to return to the steering wheel middle driving range through a return positive motor, the piston in the hydraulic cylinder is controlled to be in the piston middle driving range through a control system hydraulic flow, so that the straight driving of a vehicle is ensured, and the steering wheel middle driving range is a second set range which deviates from the steering wheel corner and is 0; the middle running range of the piston is a fourth set range with the offset displacement of 0; the second setting range is smaller than the first setting range; the fourth setting range is smaller than the third setting range.
2. The control method of the hydraulic steering system according to claim 1, characterized in that the temperature of the hydraulic cylinder is obtained in the step 1), if the temperature is greater than or equal to a first temperature threshold value, the power limit output of the hydraulic steering system is controlled, and if the temperature is greater than or equal to a second temperature threshold value, the hydraulic steering system is controlled to be stopped, wherein the second temperature threshold value is greater than the first temperature threshold value.
3. The control method of a hydraulic steering system according to claim 1, wherein the closed-loop control is performed based on the feedback amount of the displacement of the piston in the hydraulic cylinder and the feedback amount of the steering wheel angle during the return of the vehicle.
4. The control method of the hydraulic steering system according to claim 1, 2 or 3, characterized in that if the steering wheel torque is larger than or equal to the set lower torque limit and the duration of the steering wheel torque is larger than or equal to the set lower duration limit, the vehicle has a steering action, the steering wheel turning speed and the vehicle speed are obtained, and the hydraulic flow of the system is controlled according to the steering wheel turning angle, the steering wheel turning speed and the vehicle speed, so that the displacement of the piston in the hydraulic cylinder is increased, and the vehicle steering is realized.
5. The control method of the hydraulic steering system according to claim 4, wherein the hydraulic flow in the hydraulic cylinder is detected in real time during steering of the vehicle, and the closed-loop control is performed based on the feedback amount of the hydraulic flow in the hydraulic cylinder.
6. A control arrangement for a hydraulic steering system, characterized by a processor, a memory and a computer program stored in the memory and executable on the processor, which when executing the computer program implements a control method for a hydraulic steering system according to any one of claims 1-5.
7. A hydraulic steering system comprises a hydraulic oil circulation pipeline consisting of a steering oil tank, an electric steering oil pump, an electric control steering hydraulic valve group and a hydraulic cylinder and is used for driving wheels to steer, and the hydraulic steering system is characterized by further comprising a back-positive motor used for driving a steering wheel to return to the positive position, a corner sensor used for collecting the corner of the steering wheel, a torque sensor used for collecting the torque of the steering wheel, a displacement sensor used for collecting the displacement of a piston in the hydraulic cylinder, and a control device, wherein the input end of the control device is connected with the corner sensor, the torque sensor and the displacement sensor, the output end of the control device is connected with the electric steering oil pump, the electric control steering hydraulic valve group and the back-positive motor, the control device comprises a processor, a memory and a computer program which is stored in the memory and can run on the processor, and the processor realizes the control method of the hydraulic steering system according to any one of claims 1 to 3 when executing the computer program.
8. The hydraulic steering system according to claim 7, wherein the hydraulic steering system is further configured to use a vehicle speed sensor for acquiring a vehicle speed, calculate a steering wheel rotation angle speed according to a steering wheel rotation angle acquired by the rotation angle sensor, if a steering wheel torque is greater than or equal to a set lower torque limit and a duration of the steering wheel torque is greater than or equal to a set lower duration limit, the vehicle has a steering action, and control a hydraulic flow of the system according to the steering wheel rotation angle, the steering wheel rotation angle speed and the vehicle speed, so as to increase a displacement of a piston in the hydraulic cylinder, thereby achieving steering of the vehicle.
9. The hydraulic steering system of claim 8, further comprising a flow meter for sensing hydraulic flow in the hydraulic cylinder, wherein the closed loop control is based on the feedback of hydraulic flow in the hydraulic cylinder during steering of the vehicle.
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| CN105539573A (en) * | 2015-12-07 | 2016-05-04 | 三一汽车起重机械有限公司 | Steering active returning system and method for all-terrain crane |
| CN110667562A (en) * | 2018-07-03 | 2020-01-10 | 郑州宇通客车股份有限公司 | Vehicle straight-running maintaining control method and device based on wheel rotating speed |
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| JP2604620B2 (en) * | 1988-03-15 | 1997-04-30 | 富士重工業株式会社 | Control device for vehicle power steering system |
| US5201818A (en) * | 1990-05-09 | 1993-04-13 | Koyo Seiko Co., Ltd. | Power steering apparatus |
| JP2010143241A (en) * | 2008-12-16 | 2010-07-01 | Hitachi Automotive Systems Ltd | Steering control device |
| CN109533011B (en) * | 2018-10-22 | 2020-07-03 | 清华大学 | Control method for electric auxiliary steering system of commercial vehicle |
| CN109515517A (en) * | 2018-12-11 | 2019-03-26 | 芜湖伯特利汽车安全系统股份有限公司 | A kind of running out the way identifying system and method |
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| CN105539573A (en) * | 2015-12-07 | 2016-05-04 | 三一汽车起重机械有限公司 | Steering active returning system and method for all-terrain crane |
| CN110667562A (en) * | 2018-07-03 | 2020-01-10 | 郑州宇通客车股份有限公司 | Vehicle straight-running maintaining control method and device based on wheel rotating speed |
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