Method for preventing water ingress and ice build-up and stalling of a steering gear

Abstract

The present application relates to the technical field of automobile steering system, in particular to a method for preventing water from entering and freezing and sticking of a steering machine. Compared with the prior art, the present application detects the freezing condition of the steering machine by recognizing the special mode of the rotor speed and effective torque of the power-assisted motor through software, and eliminates the freezing by applying an ice-breaking vibration torque, thereby solving the problems of belt freezing and slipping, transmission sticking, ensuring the normal transmission of power from the motor to the ball screw, and reducing the uncontrollable risk of steering operation caused by freezing. At the same time, a steering machine fault signal is sent to the driver for timely maintenance.

Description

Technical Field

[0001] This invention relates to the field of automotive steering system technology, specifically a method for preventing water ingress, ice formation, and jamming in the steering gear. Background Technology

[0002] like Figure 1 As shown, the working principle of the belt-driven electric power steering system is as follows: A torque angle sensor 5 mounted on the input shaft 4 senses the steering force exerted by the driver on the steering wheel 1. The torque angle sensor 5 then transmits the signal to the control unit 8 via the wiring harness 7. The control unit 8 processes and calculates the received signal and sends a command to the motor 9 to control the motor to rotate at a certain output torque. The motor 9 transmits the power steering torque to the recirculating ball nut 11 of the ball screw 6 transmission mechanism via the belt reduction mechanism 10. The ball bearing 12 supports and fixes the recirculating ball nut 11 within the steering gear housing. The rotation of the recirculating ball nut 11 drives the ball screw 6 to move axially, thereby driving the steering tie rod 13 to move, ultimately causing the wheels to rotate, thus realizing the electric power steering function.

[0003] The steering gear of a motor vehicle needs to achieve its intended steering function under sealed conditions. This is typically achieved through a corrugated tubular dust cover at the connection area between the ball screw and tie rod. However, this elastic dust cover, made of rubber and / or plastic, can be damaged during the steering gear's lifespan due to impacts from flying stones, animal bites, tool damage, or other influences, causing the steering system to lose its seal. While using more expensive materials can reduce the frequency of such failures, it is difficult to completely prevent them.

[0004] If the dust cover is damaged, the entire steering system loses its sealing performance. At best, moisture can enter the steering gear, causing parts to rust; at worst, when driving on roads with water depth exceeding the vehicle's maximum wading depth, or in environments such as car washes or rain showers, water entering the steering system can lead to corrosion, wear, and noise. Especially when water enters the belt drive area, in temperatures below 0°C, the belt and pulleys in the belt reduction mechanism can freeze, causing the belt drive to overload and slip. Power cannot be properly transmitted from the motor to the ball screw, thus failing to provide effective power assist. This hinders steering controllability and affects driving safety.

[0005] Patent document CN101287637B discloses a device for opening a hole in the housing of a steering mechanism. This device utilizes a component made of a special material that reacts with a liquid, causing the component to dissolve or expand, thereby loosening the locking element in the housing and forcibly opening a hole in the steering gear to drain the absorbed liquid. However, in temperatures below 0°C, even after the liquid has drained, the damp belt still risks freezing and slipping. Furthermore, using this drainage device adds more parts, increasing the cost of the steering gear. Additionally, the device becomes ineffective after its initial function and requires timely replacement, a fact that the driver cannot readily perceive.

[0006] Therefore, it is necessary to design a method to prevent water ingress and freezing of the steering gear, in order to identify the situation of water ingress and freezing of the steering gear, eliminate the freezing, solve the problems of belt freezing and slippage and transmission jamming, and ensure that power is transmitted normally from the motor to the ball screw. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method to prevent water ingress and freezing of the steering gear, so as to identify the water ingress and freezing of the steering gear, eliminate the freezing, solve the problems of belt freezing and slippage and transmission jamming, and ensure that power is normally transmitted from the motor to the ball screw.

[0008] To achieve the above purpose, the present invention is a method for preventing a steering gear from jamming due to water ingress and icing, comprising the following steps: Step 1, a torque angle sensor transmits the detected steering angle and steering torque signals to a control unit, and a rotor position sensor transmits the detected motor rotational speed and motor torque signals to the control unit; Step 2, the control unit processes and calculates the received signals; Step 3, it is determined whether condition 1a, condition 2a and condition 3a are satisfied at the same time, if yes, the process proceeds to Step 4, if no, the process returns to Step 1, wherein condition 1a is that the duration during which the absolute value of the motor rotational speed is less than N1 is ≥ t1, condition 2a is that the absolute value of the effective torque decreases below M1 at least once within t1, condition 3a is that the absolute value of the steering torque is < T, N1 is the maximum stationary rotational speed of the motor rotor when the large pulley is frozen and jammed, t1 is the time taken for the engaged belt teeth to go from loose to tight or the time taken to enter a jamming state, M1 is the effective torque at the low limit rotational speed of the motor or the torque corresponding to the static friction force during tooth engagement, and T is the maximum torque measured by the torque angle sensor; Step 4, it is determined whether condition 1b, condition 2b, condition 3b and condition 4b are satisfied at the same time, if yes, the process proceeds to Step 5, if no, the process returns to Step 1, wherein condition 1b is that the absolute value of the motor rotational speed is > N1, and the absolute value of the motor rotational speed increases within t2, and the increased absolute value of the motor rotational speed is > N2, condition 2b is that when entering the t2 interval and the absolute value of the motor rotational speed is > N1, the absolute value of the effective torque is > M3, condition 3b is that within t2, the signs of the effective torque and the motor rotational speed are the same, and the sign of the motor rotational speed does not change, condition 4b is that after the motor rotational speed is > N1, the absolute value of the effective torque decreases by more than ΔM from the maximum value in the t1 interval within Δt, t2 is the minimum acceleration time of the engaged belt teeth after exceeding the overload critical point, N2 is the minimum rotational speed of the motor rotor after the belt teeth at the small pulley end slip past the critical point, M3 is the ultimate tensile force or overload critical point that the engaged belt teeth can bear, Δt is the maximum fall time of the effective torque, and ΔM is the minimum fall value of the effective torque; Step 5, it is determined whether the absolute value of the motor rotational speed decreases to less than N1 within t3 and the sign of the motor rotational speed does not change, if yes, the process proceeds to Step 6, if no, the process returns to Step 1, wherein t3 is the minimum time for the next adjacent belt tooth to enter the engagement process; Step 6, it is determined whether the duration during which the absolute value of the motor rotational speed is less than N1 is ≥ t4, if yes, the process proceeds to Step 7, if no, the process returns to Step 1, wherein t4 is the time to exit the jamming state or t1 of the next cycle; Step 7, the value of the stick-slip counter is incremented by 1, if the value of the stick-slip counter is greater than i-1 within t5, the process proceeds to Step 8, if the value of the stick-slip counter is ≤ i-1 within t5, the process returns to Step 1, and if the time variable exceeds t5, the value of the stick-slip counter and the time variable are reset, then the process returns to Step 1, wherein t5 is the longest time interval between two consecutive detections, and i-1 is the threshold of the number of jams for confirming freezing; Step 8, the control unit activates the ice-breaking vibration torque of the motor and sends an alarm signal to the entire vehicle.

[0009] The process before step 1 includes determining the trigger of the ice-breaking vibration torque. If the ice-breaking vibration torque is triggered, the process continues to step 8; otherwise, the process continues to step 1.

[0010] The control unit processes and calculates the received signals as follows: Effective torque = steering torque × effective coefficient + motor torque, effective coefficient = (ball screw pitch × gear and rack transmission efficiency) / (belt transmission ratio × linear angle transmission ratio × belt transmission efficiency × ball screw nut transmission efficiency).

[0011] The ice-breaking vibration torque motor that activates the motor is as follows: the motor continuously outputs a pulse torque with frequency f, amplitude A, duty cycle η, and alternating vibration in both positive and negative directions.

[0012] The frequency f is 2~100Hz, the amplitude A is 1~6Nm, and the duty cycle η is 50%~100%.

[0013] Once activated, the ice-breaking vibration torque will maintain or restart the ice-breaking vibration in all subsequent ignition cycles. The parameters are: N1 > 0 rpm and < 30 rpm, t1 0~200 ms, M1 > 0 Nm and < 0.3 Nm, T > 0 Nm and < 20 Nm, t2 > 0 ms and < 100 ms, N2 50~150 rpm, M3 0.5~3 Nm, Δt 0~200 ms, ΔM 0.1~2.5 Nm, t3 > 0 ms and < 1000 ms, t4 0~200 ms, t5 10~300 s, and i-1 1~30.

[0014] Compared with existing technologies, this invention detects steering gear freezing by identifying a special pattern of the power steering motor rotor speed and effective torque through software, and eliminates freezing by applying ice-breaking vibration torque. This solves the problems of belt slippage and transmission jamming caused by freezing, ensuring that power is transmitted normally from the motor to the ball screw and reducing the risk of uncontrollable steering due to freezing. Simultaneously, it sends a steering gear fault signal to the driver for timely maintenance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a belt-driven electric power steering system.

[0016] Figure 2 This is a schematic diagram of the belt reduction mechanism.

[0017] Figure 3 This is a flowchart of the present invention.

[0018] Figure 4is a characteristic diagram of the motor rotational speed and effective torque over time according to the present invention.

[0019] Figure 5 is a characteristic diagram of the ice-breaking vibration torque according to the present invention. Detailed Description of the Embodiments

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] When the belt transmission area of the steering gear freezes, as shown in Figure 2 , the small pulley 102 is driven by the motor 9, and the large pulley 103 cannot rotate normally due to freezing and sticking. The small pulley 102 is in meshed transmission with the teeth of the belt 101 to transmit torque. When the small pulley 102 continues to rotate while the large pulley 103 remains stuck and stationary, that is, the belt transmission is subjected to an excessive load exceeding the ultimate tensile force, the belt teeth meshed with the small pulley 102 will gradually slip due to overload, resulting in transmission failure.

[0022] Referring to Figure 3 , the present invention is a method for preventing the steering gear from being stuck due to water ingress and icing, comprising the following steps: Preliminary step: trigger judgment of the ice-breaking vibration torque. If the ice-breaking vibration torque is triggered, proceed to step 8; if the ice-breaking vibration torque is not triggered, proceed to step 1.

[0023] Step 1: the torque angle sensor transmits the detected steering angle and steering torque signals to the control unit, and the rotor position sensor transmits the detected motor rotational speed and motor torque signals to the control unit.

[0024] Step 2: the control unit processes and calculates the received signals.

[0025] The specific processing and calculation of the received signals by the control unit are as follows: Effective torque = Steering torque × Effective coefficient + Motor torque, Effective coefficient = (Ball screw pitch × Rack and pinion transmission efficiency) / (Belt transmission ratio × Linear-angular transmission ratio × Belt transmission efficiency × Ball screw nut transmission efficiency).

[0026] Step 3: Determine whether condition 1a, condition 2a and condition 3a are satisfied simultaneously. If yes, proceed to step 4; if no, return to step 1. Condition 1a: the duration during which the absolute value of the motor rotational speed is less than N1 is ≥ t1. Condition 2a: the absolute value of the effective torque decreases to below M1 at least once within t1. Condition 3a: the absolute value of the steering torque < T. N1 is the maximum stationary rotational speed of the motor rotor when the large pulley is frozen and stuck, t1 is the time taken for the engaged belt teeth to go from loose to tight or the time taken to enter the stuck state, M1 is the effective torque at the low limit rotational speed of the motor or the torque corresponding to the static friction force during tooth meshing, and T is the maximum torque measured by the torque angle sensor.

[0027] Step 4: Determine if conditions 1b, 2b, 3b, and 4b are satisfied simultaneously. If yes, proceed to Step 5; otherwise, return to Step 1. Condition 1b: The absolute value of the motor speed > N1, and the absolute value of the motor speed increases within t2, with the increased absolute value of the motor speed > N2. Condition 2b: Entering the t2 interval, when the absolute value of the motor speed > N1, the absolute value of the effective torque > M3. Condition 3b: Within t2, the signs of the effective torque and motor speed are the same, and the sign of the motor speed does not change. Condition 4b: After the motor speed > N1, the absolute value of the effective torque decreases from its maximum value in the t1 interval by more than ΔM within Δt. t2 is the minimum acceleration time of the meshing belt teeth after exceeding the overload critical point. N2 is the minimum speed of the motor rotor after the small pulley end belt teeth slip after exceeding the critical point. M3 is the ultimate tensile force or overload critical point that the meshing belt teeth can withstand. Δt is the maximum effective torque drop time, and ΔM is the minimum effective torque drop value. Figure 4 As shown.

[0028] Step 5: Determine whether the absolute value of the motor speed decreases to less than N1 within t3 and the sign of the motor speed does not change. If yes, proceed to step 6; otherwise, return to step 1. t3 is the minimum time for the next adjacent belt tooth to enter the meshing process.

[0029] Step 6: Determine if the absolute value of the motor speed is less than N1 for a duration ≥ t4. If yes, proceed to step 7; otherwise, return to step 1. t4 is the time to exit the jam or t1 of the next cycle.

[0030] Step 7: Increment the sticky-slip counter value by 1. If the sticky-slip counter value is greater than i-1 within t5, proceed to step 8. If the sticky-slip counter value is less than or equal to i-1 within t5, return to step 1. If the time variable exceeds t5, reset the sticky-slip counter value and the time variable, and return to step 1. t5 is the longest time interval between two consecutive detections, and i-1 is the threshold for the number of times the freeze is confirmed.

[0031] Step 8: The control unit activates the motor's ice-breaking vibration torque and sends an alarm signal to the entire vehicle. The specific details of activating the motor's ice-breaking vibration torque are as follows: the motor continuously outputs a pulse torque with frequency f, amplitude A, duty cycle η, and alternating vibrations in both positive and negative directions, such as... Figure 5 As shown. Once the ice-breaking vibration torque is activated, it will maintain or restart the ice-breaking vibration in all subsequent ignition cycles.

[0032] The frequency f is 2~100Hz, the amplitude A is 1~6Nm, and the duty cycle η is 50%~100%.

[0033] N1 is greater than 0 rpm and less than or equal to 30 rpm, t1 is 0~200 ms, M1 is greater than 0 Nm and less than or equal to 0.3 Nm, T is greater than 0 Nm and less than or equal to 20 Nm, t2 is greater than 0 ms and less than or equal to 100 ms, N2 is 50~150 rpm, M3 is 0.5~3 Nm, Δt is 0~200 ms, ΔM is 0.1~2.5 Nm, t3 is greater than 0 ms and less than or equal to 1000 ms, t4 is 0~200 ms, t5 is 10~300 s, and i-1 is 1~30.

[0034] This invention determines whether to activate the motor's ice-breaking vibration torque by judging whether the signal state meets the characteristic law based on time change, that is, whether the steering gear has frozen, thereby preventing the steering gear from getting water in, freezing and getting stuck.

[0035] This invention detects steering gear freezing by identifying specific patterns in the rotor speed and effective torque of the power steering motor through software. It then eliminates the freezing by applying ice-breaking vibration torque, solving problems such as belt slippage and transmission jamming. This ensures normal power transmission from the motor to the ball screw, reducing the risk of uncontrollable steering due to freezing. Simultaneously, it sends a steering gear fault signal to the driver for timely maintenance.

Claims

1. A method for preventing water ingress, ice formation, and jamming in a steering gear, characterized in that: comprising the following steps: Step 1, a torque angle sensor transmits the detected steering angle and steering torque signals to a control unit, and a rotor position sensor transmits the detected motor rotational speed and motor torque signals to the control unit; Step 2, the control unit processes and calculates the received signals; Step 3, determining whether condition 1a, condition 2a, and condition 3a are satisfied at the same time, if yes, proceeding to Step 4, if no, returning to Step 1, where condition 1a is that the duration for which the absolute value of the motor rotational speed is smaller than N1 is ≥ t1, condition 2a is that the absolute value of the effective torque drops below M1 at least once within t1, condition 3a is that the absolute value of the steering torque is < T, N1 is the maximum stationary rotational speed of the motor rotor when the large pulley is frozen and stuck, t1 is the time for the engaged belt teeth to go from loose to tight or the time to enter a stuck state, M1 is the effective torque of the motor at the low limit rotational speed or the torque corresponding to the static friction force during tooth engagement, and T is the maximum value of the torque measured by the torque angle sensor; Step 4, determining whether condition 1b, condition 2b, condition 3b, and condition 4b are satisfied at the same time, if yes, proceeding to Step 5, if no, returning to Step 1, where condition 1b is that the absolute value of the motor rotational speed is > N1, the absolute value of the motor rotational speed increases within t2, and the absolute value of the increased motor rotational speed is > N2, condition 2b is that when entering the t2 interval and the absolute value of the motor rotational speed is > N1, the absolute value of the effective torque is > M3, condition 3b is that within t2, the signs of the effective torque and the motor rotational speed are the same, and the sign of the motor rotational speed does not change, condition 4b is that after the motor rotational speed is > N1, the absolute value of the effective torque decreases by more than ΔM from the maximum value in the t1 interval within Δt, t2 is the minimum acceleration time of the engaged belt teeth after exceeding the overload critical point, N2 is the minimum rotational speed of the motor rotor after the belt teeth at the small pulley end slip past the critical point, M3 is the ultimate tensile force or overload critical point that the engaged belt teeth can bear, Δt is the maximum drop time of the effective torque, and ΔM is the minimum drop value of the effective torque; Step 5, determining whether the absolute value of the motor rotational speed decreases to less than N1 within t3 and the sign of the motor rotational speed does not change, if yes, proceeding to Step 6, if no, returning to Step 1, where t3 is the minimum time for the next adjacent belt tooth to enter the engagement process; Step 6, determining whether the duration for which the absolute value of the motor rotational speed is less than N1 is ≥ t4, if yes, proceeding to Step 7, if no, returning to Step 1, where t4 is the time to exit the stuck state or t1 of the next cycle; Step 7, incrementing the value of the stick-slip counter by 1, if the value of the stick-slip counter is greater than i-1 within t5, proceeding to Step 8, if the value of the stick-slip counter is ≤ i-1 within t5, returning to Step 1, and if the time variable exceeds t5, resetting the value of the stick-slip counter and the time variable before returning to Step 1, where t5 is the longest time interval between two consecutive detections, and i-1 is the threshold for the number of stuck times for confirming freezing; Step 8, the control unit activates the ice-breaking vibration torque of the motor and sends an alarm signal to the entire vehicle.

2. The method for preventing water ingress, ice formation, and jamming in a steering gear according to claim 1, characterized in that: The process before step 1 includes determining the trigger of the ice-breaking vibration torque. If the ice-breaking vibration torque is triggered, the process continues to step 8; otherwise, the process continues to step 1.

3. The method for preventing water ingress, freezing, and jamming of a steering gear according to claim 1, characterized in that: The control unit processes and calculates the received signals as follows: Effective torque = steering torque × effective coefficient + motor torque, effective coefficient = (ball screw pitch × gear and rack transmission efficiency) / (belt transmission ratio × linear angle transmission ratio × belt transmission efficiency × ball screw nut transmission efficiency).

4. The method for preventing water ingress and freezing of a steering gear according to claim 1, characterized in that: The ice-breaking vibration torque motor that activates the motor is as follows: the motor continuously outputs a pulse torque with frequency f, amplitude A, duty cycle η, and alternating vibration in both positive and negative directions.

5. The method for preventing water ingress, freezing, and jamming of a steering gear according to claim 4, characterized in that: The frequency f is 2~100Hz, the amplitude A is 1~6Nm, and the duty cycle η is 50%~100%.

6. The method for preventing water ingress and freezing of a steering gear according to claim 1, characterized in that: Once activated, the ice-breaking vibration torque will be maintained or restarted in all subsequent ignition cycles.

7. The method for preventing water ingress, freezing, and jamming of a steering gear according to claim 1, characterized in that: The following parameters are defined: N1 is greater than 0 rpm and less than or equal to 30 rpm; t1 is 0~200 ms; M1 is greater than 0 Nm and less than or equal to 0.3 Nm; T is greater than 0 Nm and less than or equal to 20 Nm; t2 is greater than 0 ms and less than or equal to 100 ms; N2 is 50~150 rpm; M3 is 0.5~3 Nm; Δt is 0~200 ms; ΔM is 0.1~2.5 Nm; t3 is greater than 0 ms and less than or equal to 1000 ms; t4 is 0~200 ms; t5 is 10~300 s; and i-1 is 1~30.

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