Steering gear locking clearance detection system and detection method

Abstract

This invention discloses a steering gear locking clearance detection system and method. The locking assembly includes a housing and a steering nut, a driven wheel, and a bearing respectively disposed inside the housing. The driven wheel and the bearing are respectively fastened to the outer peripheral wall of the steering nut. A locking plug is disposed between the bearing and the driven wheel. Wave spring washers are respectively provided between the end face of the locking plug facing the bearing and the outer ring of the bearing, and between the side of the outer ring of the bearing away from the locking plug and the inner wall of the housing. The detection assembly includes a torque control module, a displacement detection module, and a processing module. The torque control module is used to apply an initial tightening torque to the locking plug. The displacement detection module is used to detect the axial displacement of the end face of the driven wheel. The processing module is connected to the tightening torque control module and the displacement detection module respectively. The torque control module calculates the tightening torque obtained according to the target clearance value preset by the processing module and adjusts the tightening torque of the locking plug.

Description

Technical Field

[0001] This invention relates to the field of steering system technology, and more specifically to a steering gear locking clearance detection system and detection method. Background Technology

[0002] In rack and pinion electric power steering systems, the ball screw nut is typically axially limited by a locking plug. To eliminate axial movement and compensate for manufacturing tolerances, existing structures often use a rubber ring between the nut and the locking plug. The elastic deformation of the rubber ring provides preload, thereby reducing or eliminating locking clearance. However, existing locking clearance control methods have the following shortcomings: First, the preload provided by the rubber ring cannot be quantified. The elastic modulus of rubber material is greatly affected by temperature, aging, and compression. Furthermore, in actual assembly, operators often rely on experience or feel to tighten the locking plug, leading to inconsistent axial preload and consequently, significant fluctuations in the locking clearance value, making it difficult to guarantee the axial stiffness and transmission accuracy of the steering system. Second, locking clearance detection methods lack online, quantitative detection capabilities. Existing detection methods mostly use feeler gauges or manual measurement, which is not only inefficient but also highly susceptible to human factors, making it impossible to achieve rapid and accurate clearance determination on the assembly line. Summary of the Invention

[0003] To address the technical problem that existing locking clearance control methods cannot guarantee the axial stiffness and transmission accuracy of steering systems, this invention proposes a steering gear locking clearance detection system and method. By symmetrically arranging the double-wave spring pads in the locking assembly, and through the closed-loop cooperation of the torque control module, displacement detection module, and processing module in the detection assembly, the locking clearance is precisely controlled within the target range. This avoids preload fluctuations caused by unstable material properties of the rubber ring, significantly improving the accuracy and repeatability of clearance control.

[0004] The technical solution adopted by this invention is as follows: A steering gear locking clearance detection system includes a locking assembly and a detection assembly. The locking assembly includes a housing and a steering nut, a driven wheel, and a bearing respectively disposed inside the housing. The driven wheel and the bearing are respectively fastened to the outer peripheral wall of the steering nut. A locking plug is disposed between the bearing and the driven wheel. Wave spring washers are respectively provided between the end face of the locking plug facing the bearing and the outer ring of the bearing, and between the side of the outer ring of the bearing away from the locking plug and the inner wall of the housing. The detection assembly includes a torque control module, a displacement detection module, and a processing module. The torque control module is used to apply an initial tightening torque to the locking plug. The displacement detection module is used to detect the axial displacement of the end face of the driven wheel. The processing module is connected to the tightening torque control module and the displacement detection module respectively. The torque control module calculates the tightening torque obtained according to the target clearance value preset by the processing module and adjusts the tightening torque of the locking plug.

[0005] Optionally, the displacement detection module includes a probe and a displacement sensor connected to the probe. The probe is used to abut against the end face of the driven wheel, and the displacement sensor is used to read the displacement detected by the probe.

[0006] Optionally, the locking plug includes an annular wall and a locking surface perpendicularly connected to the annular wall. The inner wall of the annular wall is provided to mate with the outer wall of the bearing, and the outer wall of the annular wall is connected to the inner wall of the housing by threads. One of the wave spring washers is disposed between the locking surface and the outer ring of the bearing.

[0007] This invention also discloses a detection method based on the steering gear locking clearance detection system described above, comprising the following steps:

[0008] S1. Establish a quantitative relationship model between tightening torque and locking clearance. Drive the locking screw to the critical tightening torque T1 through the torque control module, so that the wave spring washer is about to be flattened. Then continue to drive the locking screw to the initial tightening torque. Tighten to flatten the wave spring pad;

[0009] S2. Place the probe against the end face of the driven pulley to position it and complete the zeroing operation. Set the probe measurement value at this time to the initial gap zero point. =0, obtain the initial gap reference value;

[0010] S3. Based on the target gap value S preset by the processing module target Based on the quantitative relationship model between tightening torque and locking clearance established in step S1, the corresponding target tightening torque value is calculated in reverse. ;

[0011] S4. Adjust the tightening torque of the locking plug to the target calculated tightening torque value using the torque control module. After adjustment, data is collected in real time using a probe to obtain the actual gap value S of the locking screw after adjustment. act ;

[0012] S5. Based on the initial zero point after clearing. The actual gap value S collected act The current locking gap difference is calculated. ;

[0013] S6. Determine whether the current gap difference ΔS is less than the target gap value S. target If the judgment result is yes, the locking gap is deemed qualified, the test result is output and relevant data is recorded; if the judgment result is no, the tightening torque value is finely adjusted based on the deviation between the current gap difference and the target gap. Then return to step S4 to re-execute the torque adjustment, data acquisition and gap calculation process until the gap meets the standard.

[0014] Optionally, the quantitative relationship model includes the relationship between the tightening torque of the locking screw and the axial preload, the relationship between the axial load of the wave spring pad and the deformation, and the relationship between the remaining gap of the wave spring pad after compression and the deformation.

[0015] Optionally, the relationship between the tightening torque and the axial preload of the locking plug is as follows:

[0016]

[0017] Where T is the tightening torque, K is the torque coefficient, F is the axial preload, and d is the nominal diameter of the locking plug thread.

[0018] Optionally, the wave spring pad is a circular, wavy elastic pad, and the relationship between the axial load and deformation of the wave spring pad is as follows:

[0019]

[0020] Where k is the stiffness of the wave spring washer, and K' is a correction factor related to the shape of the wave spring washer.

[0021]

[0022] R0 is the outer radius of the wave spring pad, R t Where is the inner radius of the wave spring pad; N is the wave number of the wave spring pad; B is the width of the wave spring pad; t is the thickness of the wave spring pad; E is the elastic modulus of the wave spring pad; δ is the overall deformation of the wave spring pad; D m This is the median diameter of the wave spring pad.

[0023] Optionally, the relationship between the remaining gap after compression of the wave spring pad and the amount of deformation is expressed as follows:

[0024] S=2(h-δ)

[0025] Where S is the remaining gap, h is the free height of the wave spring pad, and δ is the deformation of the wave spring pad.

[0026] Optionally, the initial tightening torque is greater than or equal to the torque required to flatten the wave spring pad.

[0027] Optionally, the calculated tightening torque value is less than the initial tightening torque.

[0028] The beneficial effects of the present invention are: (1) By symmetrically arranging the double wave spring pads in the locking assembly, and by the closed-loop cooperation of the torque control module, displacement detection module and processing module in the detection assembly, compared with the existing method of using rubber rings and relying on experience to tighten, the required tightening torque can be calculated in reverse according to the preset target gap value, and automatically adjusted by the torque control module, so that the locking gap is accurately controlled within the target range, avoiding the pre-tightening force fluctuation caused by the unstable material properties of the rubber ring, and significantly improving the accuracy and repeatability of gap control.

[0029] (2) A displacement detection module consisting of a probe and a displacement sensor is used to directly measure the axial displacement against the end face of the driven wheel. This allows for rapid clearance detection on the assembly line without disassembly or the use of manual tools such as feeler gauges. The detection process is automated, and data can be recorded in real time, avoiding human measurement errors and improving detection efficiency and reliability. Through the quantitative relationship model set by the processing module, zero-point calibration, target torque calculation, torque adjustment, and displacement determination are performed sequentially for each product, ensuring a high degree of consistency in the locking clearance values ​​of products in the same batch. Compared with existing assembly methods that rely on operational experience, this invention eliminates individual differences, reduces rework rates and after-sales failure rates, and achieves consistent quality control in mass production. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the locking assembly of the steering gear locking clearance detection system proposed in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the steering gear locking clearance detection system proposed in an embodiment of the present invention;

[0032] Figure 3 This is the target calculation torque feedback adjustment algorithm for the steering gear locking clearance detection system proposed in this embodiment of the invention.

[0033] The markings in the attached figures are as follows: 1. Housing; 2. Steering nut; 3. Driven wheel; 4. Bearing; 5. Locking plug; 51. Annular wall; 52. Locking surface; 6. Wave spring washer. Detailed Implementation

[0034] The present application will now be described in further detail with reference to the accompanying drawings and embodiments.

[0035] like Figure 1 and 2As shown, this embodiment discloses a steering gear locking clearance detection system, including a locking assembly and a detection assembly. The locking assembly includes a housing and a steering nut, a driven wheel, and a bearing respectively disposed inside the housing. The steering nut is a ball screw nut, which contains balls to convert rotational motion into rack linear motion. The driven wheel is a driven pulley that receives motor torque via a synchronous belt. The bearing is a four-point contact ball bearing, capable of simultaneously bearing axial bidirectional loads and radial loads, providing high-rigidity rotational support for the steering nut. The driven wheel and the bearing are respectively fastened to the outer peripheral wall of the steering nut. A tolerance ring is provided between the driven wheel and the steering nut, which realizes interference compensation between the driven wheel and the steering nut, provides micro-slip damping, and allows the driven wheel to receive torque transmitted by the motor through the synchronous belt, driving the steering nut to rotate.

[0036] A locking plug is located between the bearing and the driven wheel. Specifically, the locking plug includes an annular wall and a locking surface perpendicularly connected to the annular wall. The inner wall of the annular wall has a guide surface or clearance fit surface that mates with the outer wall of the bearing, and the outer wall of the annular wall is connected to the inner wall of the housing by threads. A wave spring washer is provided between the end face of the locking plug facing the bearing (i.e., the locking surface) and the outer ring of the bearing; a wave spring washer is also provided between the side of the outer ring of the bearing facing away from the locking plug and the inner wall of the housing. The two wave spring washers have the same structure, both being circular, wavy elastic washers. The two wave spring washers are coaxially mounted on the steering nut to provide axial elastic preload and eliminate axial clearance.

[0037] The detection assembly includes a torque control module, a displacement detection module, and a processing module. The torque control module is an electric torque wrench or a servo tightening shaft that engages with the head of the locking plug to apply a controllable tightening torque. The displacement detection module includes a probe and a displacement sensor connected to the probe. The tip of the probe rests against the end face of the driven wheel, and the displacement sensor is a high-precision inductive or laser displacement sensor used to read the axial displacement detected by the probe. The processing module is a programmable logic controller (PLC) or an industrial computer, electrically connected to both the torque control module and the displacement sensor. The processing module has a preset target gap value (e.g., 0.1 mm) and a quantitative relationship model between tightening torque and gap. The torque control module automatically adjusts the tightening torque of the locking plug based on the calculated tightening torque value obtained from the processing module.

[0038] This invention also discloses a method for detecting steering gear locking clearance, which uses the system described above to detect steering gear locking clearance. The specific steps are as follows:

[0039] S1: System initialization and initial tightening

[0040] First, based on the geometric parameters of the wave spring washer (k=7.3N / mm, h=1.5mm) and the thread parameters of the locking plug (M98×1.5, d=98mm, K≈0.2), a quantitative relationship model between the tightening torque and the locking clearance is established. This model includes three sub-relationships: (1) The relationship between the tightening torque T of the locking plug and the axial preload F: (2) Relationship between axial load P and deformation δ of a single wave spring pad:

[0041] The correction factor K', which is related to the shape of the wave spring washer, is: k is the stiffness of the wave spring washer, R0 is the outer radius of the wave spring washer, and R t Where is the inner radius of the wave spring pad; N is the wave number of the wave spring pad; B is the width of the wave spring pad; t is the thickness of the wave spring pad; E is the elastic modulus of the wave spring pad; δ is the overall deformation of the wave spring pad; D m The mean diameter of the wave spring pad. (3) The relationship between the remaining gap value S after the two wave spring pads are compressed and the axial movement X of the driven wheel end face. Since the two wave spring pads are symmetrically arranged, when the locking screw is loosened from the flat state to the target torque, the rebound deformation of each wave spring pad is X. The total rebound of the two pads is the remaining gap, so S = 2X. At the same time, the deformation δ of a single wave spring pad is equal to the movement X of the driven wheel end face, that is, δ = X. Combining the load deformation relationship of the wave spring pads and the tightening torque formula, the relationship between the tightening torque T and the target gap S can be obtained:

[0042]

[0043] Where S is the remaining gap, h is the free height of the wave spring pad, and δ is the deformation of the wave spring pad.

[0044] The critical state when the locking plug is about to contact the wave plate is reached. At this point, the locking plug has been screwed in to a certain depth with a tightening torque, which is determined by 5% of the flattening torque. T1 = 5% × T0 = 11 Nm. From T1 to the flattening torque T0, the torque increases linearly, ΔT = kKdδ. Therefore, the calculated torque to reach the target gap value is:

[0045]

[0046] Tighten the locking plug to the initial tightening torque T0. T0 should be greater than or equal to the torque required to completely flatten the two wave spring washers; in this embodiment, T0 = 220 N·m (i.e., flattening torque). At this point, the wave spring washers are flattened, and the gap S = 0. Place the probe against the end face of the driven wheel, and set the displacement sensor reading to zero. This step eliminates the initial positional differences during assembly, providing a reference for subsequent relative measurements.

[0047] S2: Probe zero-point calibration

[0048] Place the probe against the end face of the driven wheel to position it and complete the zeroing operation. Set the probe measurement value at this point as the initial zero point. This step involves obtaining the initial clearance reference value, which eliminates initial positional differences in assembly and provides a reference for subsequent relative measurements.

[0049] S3: Preset target gap threshold S in the target torque calculation and processing module target = 0.1 mm. The corresponding target movement X target =S target / 2 = 0.05 mm. According to the relationship δ = X, the required deformation of a single gasket is δ = 0.05 mm. Substituting δ into the load formula to calculate P, and then substituting it into the tightening torque formula to obtain the calculated tightening torque. Calculations show that... ≈110 N·m. This value is less than the flattening torque of 220 N·m, which is in accordance with the laws of physics.

[0050] S4: Target Torque Adjustment and Data Acquisition

[0051] The torque control module reverses the tightening torque of the locking plug from 220 N·m to 110 N·m. After adjustment, data is collected in real time using a probe to obtain the actual movement X of the driven wheel end face after the locking plug adjustment. act At this point, the wave spring pad partially rebounds, and the driven wheel moves axially under the action of the elastic force. The actual measured movement is X. act = 0.045 mm.

[0052] S5: Current Gap Calculation

[0053] Based on the initial zero point after clearing Compared with the actual movement X collected act =0.045 mm, the current clearance difference ΔS = 2 × X is calculated. act = 0.09 mm

[0054] S6: Determine compliance

[0055] Determine whether the current clearance difference ΔS (0.09 mm) is less than the target clearance value S. target (0.1 mm). If 0.09 < 0.1, the judgment result is yes, then the locking gap is deemed qualified, the test result is output and the relevant data is recorded.

[0056] If the determination result is negative, then the target tightening torque value is finely adjusted based on the deviation between the current clearance difference and the target clearance. Then return to step S4 to re-execute the torque adjustment, data acquisition and gap calculation process until the gap meets the standard.

[0057] By controlling the tightening torque of the locking screw The compression amount δ of the gaskets is controlled to ensure that the remaining gap S after the double gaskets are compressed is less than 0.1 mm. Therefore, during the second probe test, the tightening torque applied only needs to be equal to the calculated value. If the pressure is less than the flattening torque, the probe movement distance can be guaranteed to be less than 0.05mm each time, and the detection gap value can be less than 0.1mm, thus achieving batch consistency control.

[0058] During the adjustment of the target calculated torque, for the effective wave spring washer sample, its stiffness range should be k≤7.3±10%, that is, the adjustment torque should be within ΔT≤ If the gap is only acceptable if the adjustment is outside the ± 10% range, then the wave spring washer is deemed unqualified and the gap cannot meet the standard.

[0059] Adjust the tightening torque to the torque at which the design clearance value (i.e., the torque calculated based on the torque-clearance value relationship) is less than 0.1mm. Then, place the probe against the end face of the pulley again. At this time, the end face of the pulley should move outward by X (<0.05mm). If the equipment displays a value of X (<0.05mm), then the clearance value S = 2X (<0.1mm), and the clearance value of this part is qualified.

[0060] It is understood that the specific embodiments described above are merely for explaining the relevant invention and not for limiting the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict with each other. Any equivalent structural transformations made based on the content of this specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of this invention.

Claims

1. A steering gear locking clearance detection system, characterized in that, Includes locking components and detection components. The locking assembly includes a housing and a steering nut, a driven wheel, and a bearing respectively disposed inside the housing. The driven wheel and the bearing are respectively fastened to the outer peripheral wall of the steering nut. The locking plug is disposed between the bearing and the driven wheel. Wave spring washers are respectively provided between the end face of the locking plug facing the bearing and the outer ring of the bearing, and between the side of the outer ring of the bearing away from the locking plug and the inner wall of the housing. The detection component includes a torque control module, a displacement detection module, and a processing module. The torque control module is used to apply an initial tightening torque to the locking plug. The displacement detection module is used to detect the axial displacement of the driven wheel end face. The processing module is connected to the tightening torque control module and the displacement detection module respectively. The torque control module calculates the tightening torque based on the target gap value preset by the processing module and adjusts the tightening torque of the locking plug.

2. The steering gear locking clearance detection system according to claim 1, characterized in that, The displacement detection module includes a probe and a displacement sensor connected to the probe. The probe is used to abut against the end face of the driven wheel, and the displacement sensor is used to read the displacement detected by the probe.

3. The steering gear locking clearance detection system according to claim 1, characterized in that, The locking plug includes an annular wall and a locking surface perpendicularly connected to the annular wall. The inner wall of the annular wall is provided to mate with the outer wall of the bearing. The outer wall of the annular wall is connected to the inner wall of the housing by threads. One of the wave spring washers is disposed between the locking surface and the outer ring of the bearing.

4. A detection method based on the steering gear locking clearance detection system according to claim 2, characterized in that, Includes the following steps: S1. Establish a quantitative relationship model between tightening torque and locking clearance. Drive the locking screw to the critical tightening torque T1 through the torque control module, so that the wave spring washer is about to be flattened. Then continue to drive the locking screw to the initial tightening torque. Tighten to flatten the wave spring pad; S2. Place the probe against the end face of the driven pulley to position it and complete the zeroing operation. Set the probe measurement value at this time to the initial gap zero point. =0, obtain the initial gap reference value; S3. Based on the target gap value S preset by the processing module target Based on the quantitative relationship model between tightening torque and locking clearance established in step S1, the corresponding target tightening torque value is calculated in reverse. ; S4. Adjust the tightening torque of the locking plug to the target calculated tightening torque value using the torque control module. After adjustment, data is collected in real time using a probe to obtain the actual gap value S of the locking screw after adjustment. act ; S5. Based on the initial zero point after clearing. The actual gap value S collected act The current locking gap difference is calculated. ; S6, judging whether the current gap difference value AS is less than the target gap value S target ; If the result is yes, the locking gap is deemed to be qualified, the test result is output and the relevant data is recorded; If the determination result is negative, then the target tightening torque value is finely adjusted based on the deviation between the current clearance difference and the target clearance. Then return to step S4 to re-execute the torque adjustment, data acquisition and gap calculation process until the gap meets the standard.

5. The detection method according to claim 4, characterized in that, The quantitative relationship model includes the relationship between the tightening torque of the locking screw and the axial preload, the relationship between the axial load and the deformation of the wave spring pad, and the relationship between the remaining gap and the deformation of the wave spring pad after compression.

6. The detection method according to claim 5, characterized in that, The relationship between the tightening torque and the axial preload of the locking plug is as follows: ， Where T is the tightening torque, K is the torque coefficient, F is the axial preload, and d is the nominal diameter of the locking plug thread.

7. The detection method according to claim 5, characterized in that, The wave spring pad is a circular, wavy elastic pad, and the relationship between the axial load and deformation of the wave spring pad is as follows: ， Where k is the stiffness of the wave spring washer, and K' is a correction factor related to the shape of the wave spring washer. ， R0 is the outer radius of the wave spring pad, R t is the inner radius of the wave spring pad, N is the wave number of the wave spring pad; B is the width of the wave spring pad; t is the thickness of the wave spring pad; E is the elastic modulus of the wave spring pad; δ is the overall deformation of the wave spring pad; D m is the mean diameter of the wave spring pad.

8. The detection method according to claim 5, characterized in that, The relationship between the remaining gap and deformation of the waveform spring pad after compression is expressed as follows: S=2(h-δ) Where S is the remaining gap, h is the free height of the wave spring pad, and δ is the deformation of the wave spring pad.

9. The detection method according to claim 5, characterized in that, The initial tightening torque is greater than or equal to the torque required to flatten the wave spring pad.

10. The detection method according to claim 5, characterized in that, The calculated tightening torque value is less than the initial tightening torque.

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