A shift cable dynamic friction coefficient measurement method

Abstract

The application provides a kind of shift cable dynamic friction coefficient measurement method, it is related to cable detection technical field.The application is by collecting the push-pull measurement data of shift cable input end and output end and recording bending path, according to the push-pull stroke continuation process after input end idle stroke section turns into load section, determines input end sampling range, according to the push-pull load bearing change caused by the transmission of push-pull effect through bending path determines output end sampling range, then with the start of push-pull stroke of output end changes to check the start point of bearing stroke, intercepts the double-end data of the same core line slip process, separates the dynamic friction coefficient after converting the deformation load of cable structure.The application is beneficial to reduce the influence of double-end data state mismatch on dynamic friction coefficient measurement.

Description

Technical Field

[0001] This invention relates to the field of cable testing technology, and in particular to a method for measuring the dynamic friction coefficient of a shift cable. Background Technology

[0002] As a flexible force transmission component in a vehicle's shift control system, the shift cable's friction performance directly affects the transmission of operating force, the stability of shift feel, and the consistency of movement after long-term use. With the increasing demands for overall vehicle handling quality, relying solely on static push-pull force or transmission efficiency is no longer sufficient to meet the testing requirements for process-oriented characterization of the dynamic friction state of the shift cable.

[0003] Existing shift cable testing methods typically rely on load changes during the push-pull stroke, focusing on the overall transmission performance between the input and output loads. However, due to the bending and flexible deformation of shift cables in actual installation, the input action undergoes internal tensioning, contact state changes, and end response establishment before being transmitted to the output. This means that even if the data collected from both ends are synchronized in time, they may not correspond to the same internal sliding state.

[0004] Therefore, when measuring the dynamic friction coefficient of the shift cable, if the data from both ends at the same sampling time is used directly as the basis for calculation, it is easy to mix the load changes caused by structural deformation, force transmission lag and end response into the friction calculation results. This makes it difficult for the measured dynamic friction coefficient to truly reflect the body friction characteristics between the core wire and the liner, thus affecting the performance evaluation of the shift cable and the judgment of abnormal causes. Summary of the Invention

[0005] To address the problem in existing methods for measuring the dynamic friction coefficient of shifting guy wires, where the input and output data are difficult to correlate with the actual sliding state of the core wire within the liner, leading to the inclusion of structural deformation and force transmission lag in the dynamic friction coefficient calculation results, this invention proposes a method for measuring the dynamic friction coefficient of shifting guy wires. This method uses the input and output sampling ranges, along with load data from the same core wire sliding process, to ensure that the data used in the friction conversion corresponds to the relative sliding state between the core wire and the liner.

[0006] This was achieved through the following technical solutions: A method for measuring the dynamic friction coefficient of a shift cable includes: collecting push-pull measurement data at the input and output ends of the shift cable and recording the bending path of the shift cable; determining the input end sampling range for the core wire sliding inside the liner based on the push-pull stroke continuity process after the idle section transitions into the bearing section in the input end push-pull measurement data; determining the output end sampling range based on the output end push-pull load change caused by the push-pull action transmitted along the bending path of the shift cable within the input end sampling range in the output end push-pull measurement data; verifying the starting point of the bearing stroke in the input end sampling range with the initial change of the push-pull stroke in the output end sampling range, and extracting data from both ends of the same core wire sliding process; separating the load generated by the deformation of the cable structure to form load data corresponding to the relative sliding of the core wire and the liner; and converting the load data into the dynamic friction coefficient of the shift cable corresponding to the same core wire sliding process according to the core wire force transmission process defined by the bending path.

[0007] Preferably, the push-pull measurement data are data generated in the same push-pull detection stroke according to the sampling sequence, including input push-pull measurement data and output push-pull measurement data. Both the input and output push-pull measurement data contain push-pull load, push-pull stroke, and push-pull direction, and have a common sampling sequence reference. By obtaining data from both ends under the common sampling sequence reference, a data basis can be provided for subsequent determination of the connection between the input and output data.

[0008] Preferably, the process of determining the input sampling range includes: reading the sampling interval in the input push-pull measurement data where the push-pull stroke occurs before the change in the push-pull load, and determining the idle stroke segment; reading the sampling position where the push-pull load enters the load change along the same push-pull direction after the idle stroke segment, and determining the starting point of the load segment; cross-comparing the portion of the push-pull stroke that advances after the starting point of the load segment with the portion of the push-pull load that enters the load change sampling segment, and determining the input sampling range. This process reduces the impact of the end idle stroke on the determination of the input sampling range.

[0009] Preferably, the process of determining the idle segment includes: reading the continuous advancement portion of the input end push-pull stroke along the same push-pull direction, marking the sampling position where the push-pull load has not yet entered the load change phase; connecting the sampling positions according to the sampling sequence, and determining the idle segment based on the last sampling position before the push-pull load leaves the no-load fluctuation. In this way, the stage where the input end push-pull stroke has occurred but the push-pull load has not yet entered the load change phase can be distinguished from the subsequent friction conversion data.

[0010] Preferably, the process of determining the output sampling range includes: according to the push-pull direction corresponding to the input sampling range, reading the output candidate sampling interval whose sampling sequence is after the starting point of the input sampling range from the output push-pull measurement data; cross-comparing the sampling portion where the push-pull load changes and the sampling portion where the push-pull stroke continues to advance within the output candidate sampling interval, retaining the sampling portion where the two are connected in the sampling sequence; and determining the output sampling range by combining the position of the output push-pull load change, the position of the continuous advancement of the output push-pull stroke, and the path sequence of the bending path. This process avoids directly using the output data at the same sampling moment as the corresponding data for the input data.

[0011] Preferably, the bending path has bending segments arranged along the push-pull direction of the core wire; the bending segment correspondingly records the bending position, bending angle, and bending direction; the arrangement order of the bending segments is consistent with the path order from the input end to the output end. By recording the bending path, a basis can be provided for determining the continuity of the sampling range at the output end and for determining the subsequent cumulative wrap angle.

[0012] Preferably, the load data formation process includes: verifying the candidate starting point of the load stroke within the input sampling range based on the sampling position where the push-pull stroke begins to advance continuously in the output sampling range, and determining the starting point of the load stroke; using the starting point of the load stroke as the input interception starting point, determining the interception endpoint within the output sampling range, and intercepting the double-end data of the same core wire sliding process; based on the stroke difference change in the double-end data, separating the load portion corresponding to the stroke difference change from the double-end data to form the load data corresponding to the relative sliding between the core wire and the liner. Through this processing, the load data can be made closer to the body friction load generated by the relative sliding between the core wire and the liner.

[0013] Preferably, the process of determining the starting point of the load-bearing stroke includes: reading the sampling positions in the output sampling range where the push-pull stroke transitions from a stationary state to continuous advancement, and obtaining the corresponding sampling sequence; if the corresponding sampling sequence is located after the starting point of the input sampling range, then the starting point of the input sampling range is determined as the starting point of the load-bearing stroke. By verifying the candidate starting point of the input load-bearing stroke through the change in the starting point of the output push-pull stroke, the number of cases where the early structural deformation response at the input end enters the same core wire slippage process data can be reduced.

[0014] Preferably, the conversion process for the dynamic friction coefficient of the shift cable includes: determining the cumulative wrap angle along the core wire's push-pull direction based on the bending angle of each bending segment in the bending path; reading the input and output loads corresponding to the same relative slip position from the load data; and obtaining the dynamic friction coefficient of the shift cable corresponding to the same core wire slip process according to the bending friction conversion relationship between the input load, output load, and cumulative wrap angle. This conversion method incorporates the influence of the bending path on the force transmission of the core wire into the dynamic friction coefficient measurement process.

[0015] The beneficial effects of this invention compared to the prior art are: This invention determines the input sampling range based on the push-pull stroke continuity process after the empty segment transitions to the bearing segment in the input push-pull measurement data, and then determines the output sampling range based on the output bearing change caused by the transmission of the push-pull action at the input end. This makes the sampling of dual-end data no longer dependent on a single timestamp, which helps to reduce the mismatch of dual-end data states caused by end empty stroke and force transmission lag.

[0016] This invention verifies the starting point of the load-bearing stroke in the input sampling range by changing the initial push-pull stroke of the output sampling range, and extracts data from both ends of the same core wire slippage process. This allows for the differentiation between the early structural deformation response at the input end and the actual core wire slippage process, which is beneficial for improving the physical correspondence of dynamic friction coefficient measurement data.

[0017] This invention separates the load generated by the deformation of the draw wire structure to form load data corresponding to the relative sliding of the core wire and the liner tube. It also combines the force transmission process of the core wire defined by the bending path to perform friction conversion. This can reduce the influence of elastic deformation of the draw wire, sheath compression and load end start-up on the measurement results, and is conducive to obtaining a dynamic friction coefficient that is more consistent with the friction state of the core wire and the liner tube body. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for measuring the dynamic friction coefficient of a gear shift cable, as described in Example 1.

[0019] Figure 2 This is a schematic diagram of the system architecture for measuring the dynamic friction coefficient of a gear shift cable, as shown in Example 2. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 This embodiment provides a method for measuring the dynamic friction coefficient of a shift cable, applicable to the dynamic friction performance testing of shift cables on a push-pull testing bench. The shift cable includes a core wire, a bushing, a sheath, an input connector, an output connector, and a mounting support structure. During the testing process, after the input end is pushed and pulled, the core wire does not immediately form a stable slip within the bushing. Instead, it first undergoes processes such as end idle, core wire tensioning, sheath compression, bending section contact, and output end activation. Because the above processes are continuously transmitted along the length of the shift cable, even if the input and output sampling data have the same sampling clock, they may not correspond to the same core wire slip state.

[0022] In this embodiment, push-pull measurement data from both the input and output ends are recorded simultaneously during a single push-pull test stroke, and the dual-end data is processed in conjunction with the bending path of the shifting cable. The input end data is first used to determine when the core wire leaves the end idle and enters the load-bearing slippage; the output end data is then used to determine the receiving process after the push-pull action from the input end is transmitted to the output end. Subsequently, the starting point of the input end load-bearing stroke is verified by the initial change in the output end push-pull stroke, ensuring that the dual-end data involved in the friction calculation correspond to the same core wire slippage process. This processing method differs from directly pairing the dual-end force values ​​at the same sampling time, reducing interference from end idle, core wire elastic elongation, sheath compression, and load-end start-up on the dynamic friction coefficient calculation.

[0023] S101: Collect push-pull measurement data at the input and output ends of the shift cable and record the bending path of the shift cable.

[0024] Before the push-pull test begins, the shift cable is fixed on the test bench according to the predetermined installation configuration, ensuring that the core wire can complete both the pushing and pulling strokes within the liner. The input end is connected to the drive mechanism, and the output end is connected to the load or force measuring mechanism. During the test, the input and output ends record the push-pull measurement data in the same sampling sequence. The push-pull measurement data includes the push-pull load, push-pull stroke, and push-pull direction.

[0025] The input push-pull measurement data is recorded as follows: ; The push-pull measurement data at the output end is recorded as follows: ; in, This is the sampling sequence number. For the input push-pull load, For the input push-pull stroke, For the push-pull load at the output end, For the push-pull stroke of the output end, This indicates the direction of pushing or pulling.

[0026] The direction of push and pull can be represented as: ; Sampling sequence number Used to indicate the order in which data was collected, not limited to absolute time points. The input push-pull measurement data and the output push-pull measurement data share a common sampling order reference, which facilitates subsequent determination of the continuity between the input and output data.

[0027] The bending path of the shift cable is recorded based on the installation status. The bending path includes bending segments arranged along the physical path from the input to the output. For each bending segment, the bending position, bending angle, and bending direction are recorded. The bending path is denoted as: ; in, This represents the number of curved sections.

[0028] No. Each curved segment is denoted as: ; in, For the bending position, For the bending angle, The bending direction is indicated. The bending segments are arranged in the order of the path from the input end to the output end. If the testing platform can record the bending radius, the bending radius can also be used as additional data of the bending path.

[0029] To facilitate subsequent processing, the sampling order of the push-pull measurement data can be organized. Adjacent increments of the input push-pull stroke are denoted as: ; The adjacent increments of the push-pull stroke at the output end are denoted as: ; The adjacent changes in the input push-pull load are denoted as: ; The adjacent changes in the push-pull load at the output end are denoted as: ; Within a single push-pull stroke, the direction of change of the input and output push-pull strokes should match the push-pull direction. If a position in the detection data shows a change in push-pull direction, that position is taken as the boundary between adjacent single-directional strokes.

[0030] S102: Based on the push-pull stroke continuity process after the empty section enters the bearing section in the push-pull measurement data at the input end, determine the input end sampling range for the core wire to slide into the liner tube.

[0031] The sampling range at the input end is determined from the push-pull measurement data at the input end. When the push-pull stroke at the input end begins to change, the input end connector may still be in the end idle elimination stage. At this time, the push-pull stroke at the input end has advanced, but the push-pull load has not yet entered a state that can reflect the change in the core wire load. Therefore, the idle segment is identified first, then the starting point of the load segment is identified, and the sampling portion where the push-pull stroke continues to advance and the push-pull load maintains the change in load is found after the starting point of the load segment.

[0032] Specifically, the process for determining the sampling range at the input end is as follows: Read the sampling interval in the push-pull measurement data at the input end where the push-pull stroke occurs before the change in push-pull load, and determine the idle stroke segment.

[0033] In implementation, the process of determining the idle segment is as follows: Read the continuous advance portion of the input end push-pull stroke along the same push-pull direction, and mark the sampling position where the push-pull load has not yet entered the load change sampling position.

[0034] Within a unidirectional push-pull stroke, whether the input end continues to advance continuously in the current push-pull direction is determined by the input end stroke increment after direction correction. The input end stroke increment after direction correction is denoted as: ; When satisfied At this time, the input end push-pull stroke continuously advances along the current push-pull direction. When the push-pull load has not yet entered the bearing change stage, the input end push-pull load is generally within the no-load fluctuation range. The no-load fluctuation range can be obtained by detecting the load fluctuation of the testing equipment in a state without a sample or without load.

[0035] Let the no-load fluctuation limit be When satisfied When the input end push-pull stroke continues to advance along the current push-pull direction, the corresponding sampling position will be marked as the sampling position where the push-pull load has not yet entered the bearing change.

[0036] Connect the sampling positions according to the sampling order, and determine the idle segment based on the last sampling position before the push-pull load leaves the no-load fluctuation.

[0037] Connect the marked sampling locations in the sampling order to form candidate idle intervals. Within a candidate idle interval, the sampling portion that continuously satisfies the condition that the push-pull load has not yet entered a period of load change and the input push-pull stroke is advancing along the current push-pull direction is defined as an idle segment. The idle segment is denoted as: ;in, The initial sampling sequence for the idle segment. The sampling sequence is the one that terminates the idle segment; This is the last sampling position before the push-pull load is released from the no-load fluctuation.

[0038] Along the same push-pull direction after the idle section, read the sampling position where the push-pull load changes to determine the starting point of the load section.

[0039] After the idle section ends, the connection gap at the input end is eliminated, and the push-pull load at the input end begins to reflect the core wire tension and the sliding resistance within the bushing. Along the idle section... Subsequent push-pull measurements were taken in the same direction. The load change judgment limit was set to... When the sampling position after the idle segment first satisfies When the input end continues to move in the current push-pull direction, the sampling position is determined as the starting point of the bearing section, denoted as . Among them, the starting point of the bearing section Located at the end of the empty segment Afterwards, and satisfied ;exist Within the subsequent sampling range, the input push-pull load maintained its load variation, and the input push-pull stroke maintained its unidirectional advancement.

[0040] The input sampling range is determined by cross-comparing the push-pull stroke advancement part after the starting point of the load-bearing section with the sampling part where the push-pull load enters the load-bearing change section.

[0041] From the starting point of the bearing section Initially, read the input end push-pull stroke advancement section and the input end push-pull load variation section. The push-pull stroke advancement section consists of... The load varies continuously along the push-pull direction; the varying portion of the push-pull load is determined by... The state of load variation is determined. After cross-comparison of the two, the sample portion that simultaneously satisfies the requirements of push-pull stroke advancement and push-pull load variation is retained. The input sampling range is denoted as: ;in, This is the starting point of the input sampling range. This is the end point of the input sampling range. In this embodiment, the start point of the input sampling range is... That is, the starting point of the bearing section ,Right now The input sampling range corresponds to the input data segment after the core wire slides into the liner tube.

[0042] S103: In the push-pull measurement data at the output end, the output end sampling range is determined based on the change in the push-pull load at the output end caused by the transmission of the push-pull action along the bending path of the shift cable within the sampling range of the input end.

[0043] The output sampling range is determined from the output push-pull measurement data. After the push-pull action within the input sampling range is transmitted to the output along the bending path, the output first experiences a change in load bearing, followed by continuous advancement of the output push-pull stroke. Due to the state delay caused by bending section contact, sheath compression, and load-end initiation, the output sampling range does not use the same starting point as the input sampling range. Instead, it searches for an output sampling section that can withstand the input push-pull action after the starting point of the input sampling range.

[0044] The process for determining the sampling range at the output end is as follows: Based on the push-pull direction corresponding to the input sampling range, read the output candidate sampling interval from the push-pull measurement data, where the sampling order is located after the starting point of the input sampling range.

[0045] Based on the input sampling range Corresponding push and pull directions The push-pull measurement data at the output end is read within the same unidirectional push-pull stroke. The candidate sampling interval at the output end is denoted as: ;in, Located at the starting point of the input sampling range after, Located before the end of the same unidirectional push-pull stroke. The candidate sampling interval at the output end does not cross the position where the push-pull direction changes.

[0046] Cross-compare the sampling portions where the push-pull load changes and the sampling portions where the push-pull stroke advances continuously within the candidate sampling interval of the output end, and retain the sampling portions that are connected in the sampling sequence between the two.

[0047] Within the candidate sampling interval at the output end, the sampling position where the push-pull load at the output end enters the bearing change is denoted as... The sampling position at which the output end enters continuous advancement during the push-pull stroke is denoted as... .

[0048] in, To satisfy the following formula, the first sampling position is: Whether the output end push-pull stroke continues in the current push-pull direction is determined by the output end stroke increment after direction correction. The output end stroke increment after direction correction is recorded as: ; To satisfy the following formula, the first sampling position is: When satisfied When determining the output end push-pull load change and the continuous advancement of the output end push-pull stroke, the sampling sequence is sequentially related. If there is only a load change but the output end push-pull stroke does not advance continuously, this sampling part is closer to the load end preload; if there is only a fluctuation in the output end push-pull stroke but the push-pull load does not enter the load change stage, this sampling part does not participate in the determination of the output end sampling range.

[0049] The sampling range of the output end is determined by combining the position of the change in the push-pull load at the output end, the continuous advancement position of the push-pull stroke at the output end, and the path sequence of the bending path.

[0050] In satisfying In this case, the sampling position where the push-pull stroke of the output end enters continuous advancement is determined as the starting point of the output end sampling range: The endpoint of the output sampling range is the last valid sampling position before the end of the same unidirectional push-pull stroke, denoted as: The output sampling range is denoted as: The bending path is used in this step to confirm the sequence of paths from the input to the output within the current unidirectional push-pull stroke. The bending paths are arranged sequentially from input to output as follows: .

[0051] Since the drive mechanism is located at the input end, the push-pull action is transmitted along the shift cable in the order of proximity to the input end. To the output end Confirmation is required. Changing the sign of the input and output push-pull strokes does not alter the path sequence from input to output. If the output candidate sampling interval does not match the input-to-output path sequence corresponding to the curved path, then that output candidate sampling interval is not considered the output sampling range. The bending angle in the curved path is not included in the calculation of the start and end points of the output sampling range; the bending angle is used for subsequent cumulative wrap angle and bending friction conversion.

[0052] S104: Verify the starting point of the load-bearing stroke in the input sampling range by the initial change of the push-pull stroke in the output sampling range, and extract the double-end data of the same core wire sliding process; separate the load generated by the deformation of the wire structure to form the load data corresponding to the relative sliding of the core wire and the liner.

[0053] Although the input sampling range excludes idle periods, its early data may still include core wire elastic elongation, sheath compression, and structural deformation response before load initiation. Changes in the initial push-pull stroke within the output sampling range reflect when the output end has begun to accept core wire slippage. Therefore, this embodiment utilizes the initial change in the push-pull stroke within the output sampling range to verify the candidate starting point of the load-bearing stroke within the input sampling range.

[0054] The process of generating load data is as follows: Based on the sampling position where the push-pull stroke begins to advance continuously within the sampling range of the output end, verify the candidate starting point of the load stroke within the sampling range of the input end, and determine the starting point of the load stroke.

[0055] In implementation, the starting point of the carrying stroke is determined as follows: Read the sampling position where the push-pull stroke changes from stationary to continuous advancement within the sampling range of the output terminal, and obtain the corresponding sampling sequence; The position where the output end's push-pull stroke transitions from a stationary state to continuous advancement has been determined as the starting point of the output end's sampling range. Therefore, the sampling position at which the push-pull stroke at the output end begins to advance continuously is recorded as: ;in, .

[0056] If the corresponding sampling sequence is after the starting point of the input sampling range, then the starting point of the input sampling range is determined as the starting point of the carrying stroke.

[0057] Sampling range at the input end In the middle, the starting point of the bearing section and the starting point of the input sampling range All measurements are determined by the push-pull measurement data at the input end. In this embodiment, the starting point of the input end sampling range... That is, the starting point of the bearing section Output sampling range start point It is used to verify whether the input sampling range has been taken over by the output, and is not used as the starting point for truncation of input data in the same sampling sequence. If Located at the starting point of the input sampling range Subsequently, if the sampling range of the output end and the sampling range of the input end are within the same unidirectional push-pull stroke, then the starting point of the input end bearing stroke is denoted as: If no output sampling range meets the above conditions, the input sampling range will not form double-end data for the same core wire slippage process. Using this method, the input and output data are no longer forcibly aligned according to the same sampling sequence number, but instead, the starting point of the input travel and the starting point of the output sampling range are used as their respective cutoff points.

[0058] Using the starting point of the carrying stroke as the starting point of the input interception, the ending point of the interception is determined within the sampling range of the output end, and the data from both ends of the same core wire sliding process are intercepted.

[0059] From the starting point of the journey Start capturing push-pull measurement data at the input end, and start sampling from the starting point of the output range. Begin capturing push-pull measurement data at the output end. Input and output data are paired using relative sliding numbers. The relative sliding numbers are denoted as: ;in: ; when At this time, the input sampling range and the output sampling range do not form two-end data of the same core wire sliding process. For the first... The relative sliding positions correspond to the following sampling order at the input end: ; The corresponding sampling order at the output terminal is: ; The extracted two-end data is denoted as: ; in, For the first The push / pull direction corresponds to each relative sliding position. The input and output data in the dual-end data are distinguished by their relative sliding sequence numbers. Establish a corresponding relationship, and do not use the same sampling sequence number for pairing.

[0060] Based on the change in stroke difference in the double-ended data, the load portion corresponding to the change in stroke difference is separated from the double-ended data to form the load data corresponding to the relative sliding of the core wire and the bushing.

[0061] In the The relative sliding position and the relative push-pull stroke of the input end are denoted as: ; The relative push-pull stroke of the output end is denoted as: ; The travel difference fluctuation between the relative push-pull stroke of the input end and the relative push-pull stroke of the output end is denoted as: ; The stroke difference fluctuation is used to characterize the asynchronous changes between the input end push-pull stroke and the output end push-pull stroke caused by the deformation of the pull wire structure during the sliding process of the same core wire.

[0062] The structural stiffness coefficients are determined separately according to the current unidirectional push-pull direction. For the push stroke and pull stroke, the structural stiffness coefficients are denoted as follows: and The structural stiffness coefficient corresponding to the current travel distance is denoted as... In one implementation, It can be started from the bearing section. To the starting point of the sampling range at the output end The cumulative range of structural deformation between them is obtained: ; If the denominator is zero, the structural stiffness coefficient for that sampling interval will not be used to calculate the stiffness coefficient; instead, the pre-calibrated structural stiffness coefficient for the same type of shift cable in the same push-pull direction will be used. Push stroke usage... Pull to travel use .

[0063] The amount of structural deformation load compensation during the slippage of the same core wire is denoted as: ; in, Used to correct structural deformation load changes caused by stroke difference fluctuations during relative slip, and The direction is the same as the direction of the driving force in the current push-pull direction. The cumulative state of structural deformation formed between the starting point of the bearing section and the starting point of the sampling range at the output end is used to determine the time-shift pairing relationship and the structural stiffness coefficient, and is not used as a fixed load repeatedly deducted point by point during the slip process of the same core wire.

[0064] After separating the structural deformation load compensation from the two-end data, load data corresponding to the relative sliding between the core wire and the liner is generated. The load data is denoted as: ; in, The input load is the compensation amount for the structural deformation load. The load is the output load. Since the input end is connected to the drive mechanism, the structural deformation load compensation is separated from the total input load. The separated input and output loads are expressed as follows: ; ; Among them, structural deformation load compensation amount The direction of the driving force is the same as the current push-pull direction. Separation refers to subtracting the load component used to overcome the elastic deformation of the wire structure from the absolute value of the total load at the input end. If If the relative slip position is not included in the subsequent bending friction calculation, then the load data is used to characterize the load value corresponding to the relative sliding between the core wire and the liner during the same core wire slippage process.

[0065] S105: Based on the core wire force transmission process defined by the bending path, the load data is converted into the dynamic friction coefficient of the shifting tension wire corresponding to the same core wire slippage process.

[0066] Once the load data is generated, the load corresponding to the relative sliding of the core wire and the liner tube corresponds to the same core wire sliding process. The bending path defines the force transmission process of the core wire within the liner tube. When the core wire passes through the bending section, the load is transmitted along the bending path and affected by bending contact friction.

[0067] The cumulative wrap angle is determined along the push-pull direction of the core wire based on the bending angle of each bending segment in the bending path.

[0068] If the current core wire slippage process passes through all the bending segments, the cumulative wrap angle is recorded as: ; If the current core wire slippage process only passes through a portion of the bending segment, the set of bending segments involved in force transmission is denoted as... The cumulative corner coverage is recorded as follows: ; in, or The appropriate method can be selected based on the actual testing conditions. If the bending state of the shift cable remains unchanged throughout the testing process, a fixed cumulative wrap angle can be used. .

[0069] Read the input load and output load corresponding to the same relative slip position from the load data.

[0070] From load data Read the same relative sliding position and Since the input end is connected to the drive mechanism, the side corresponding to the load at the input end is the load input side, and the side corresponding to the load at the output end is the load output side. Regardless of whether the core wire push-pull direction is from the input end to the output end or from the output end to the input end, the load on the load input side and the load on the load output side are both expressed as: ; ; in, For load input side load, This is the load on the output side.

[0071] Based on the bending friction conversion relationship between input side load, output side load and cumulative wrap angle, the dynamic friction coefficient of the shifting wire corresponding to the slippage process of the same core wire is obtained.

[0072] In one implementation, the dynamic friction coefficient of the shift cable can be expressed as: ; When using the cumulative wrap angle corresponding to the relative sliding position When, it can be expressed as: ; in, For the first The dynamic friction coefficient of the shift cable corresponding to each relative slip position. For load input side load, This is the load on the output side. The following conditions must be met before substituting into the formula: ; If the above conditions are not met, it means that an effective bending friction transmission state has not been formed at the corresponding relative sliding position, and the corresponding relative sliding position is not included in the dynamic friction coefficient calculation.

[0073] After collecting the effective relative slip positions, the dynamic friction coefficient sequence is obtained: ; in, The number of effective relative sliding positions.

[0074] For continuous reciprocating push-pull testing, dynamic friction coefficient sequences can be generated separately for the pushing direction and the pulling direction. The dynamic friction coefficient sequence for the pushing direction is denoted as: ; The sequence of dynamic friction coefficients is denoted as: ; in, To push towards the number of effective relative slip positions, This represents the number of effective relative slip positions. (By comparison) and This allows us to obtain the dynamic frictional changes between the core wire and the liner under different push-pull directions.

[0075] In batch testing, the dynamic friction coefficient sequence corresponding to the same core wire sliding process can be associated and saved with the sample number, push-pull direction, bending path, and test stroke number. If the dynamic friction coefficient sequence of the same model sample under the same bending path shows a continuous deviation, the input sampling range, output sampling range, and load stroke start point can be further examined to determine whether the deviation comes from the friction change between the core wire and the liner body, or from the end assembly, sheath compression, or load start process.

[0076] In this embodiment, the input sampling range is determined by the push-pull stroke continuation process after the transition from the idle section to the bearing section, and the output sampling range is determined by the output bearing change after the input push-pull action is transmitted along the bending path. The starting point of the bearing stroke is verified by the initial change of the output push-pull stroke. Through this processing, the dual-end data are no longer directly taken according to the same sampling sequence number. Instead, the input and output data ranges corresponding to the same core wire sliding process are first formed, and then time-shifted pairing is performed through the relative sliding sequence number, and the structural deformation load compensation amount corresponding to the stroke difference fluctuation is separated. The dynamic friction coefficient obtained thus corresponds to the relative sliding process between the core wire and the liner.

[0077] Example 2 like Figure 2As shown in the example, the parts not detailed in this embodiment are as shown in Example 1. This embodiment discloses a system for measuring the dynamic friction coefficient of a shift cable, including: Acquisition and Recording Module: Used to acquire push-pull measurement data at the input and output ends of the shift cable and record the bending path of the shift cable; Input sampling module: used to determine the input sampling range of the core wire sliding into the liner tube based on the push-pull stroke continuity process after the empty section enters the bearing section in the push-pull measurement data at the input end; Output sampling module: used to determine the output sampling range based on the change in output push-pull load caused by the transmission of the push-pull action along the bending path of the shift cable within the input sampling range in the push-pull measurement data; Load forming module: used to verify the starting point of the load-bearing stroke of the input sampling range by the initial change of the push-pull stroke of the output sampling range, and to extract the double-end data of the same core wire sliding process; to separate the load generated by the deformation of the wire structure and form the load data corresponding to the relative sliding of the core wire and the liner tube; Friction conversion module: used to convert load data into the dynamic friction coefficient of the shifting tension wire corresponding to the same core wire slippage process according to the core wire force transmission process defined by the bending path.

[0078] The above embodiments are merely specific implementations of the present invention. For different models of shift cables, the sampling frequency, load range, stroke range, number of bending segments, and bending angle of the push-pull measurement data can be determined according to the detection conditions. As long as the processing logic between the input sampling range, output sampling range, load stroke start point, dual-end data, load data, and dynamic friction coefficient is followed, it falls within the scope of the technical solution of the present invention.

Claims

1. A method for measuring the dynamic friction coefficient of a gear shift cable, characterized in that, include: Collect push-pull measurement data at the input and output ends of the shift cable and record the bending path of the shift cable; Based on the push-pull travel duration after the empty section transitions into the bearing section in the input push-pull measurement data, the input sampling range for the core wire sliding into the liner tube is determined; In the push-pull measurement data at the output end, the output end sampling range is determined based on the change in the push-pull load at the output end caused by the transmission of the push-pull action along the bending path of the shift cable within the sampling range of the input end. The starting point of the load-bearing stroke in the input sampling range is verified by the initial change of the push-pull stroke in the output sampling range, and the double-end data of the same core wire sliding process are extracted; the load generated by the deformation of the wire structure is separated to form the load data corresponding to the relative sliding of the core wire and the liner tube; Based on the force transmission process of the core wire defined by the bending path, the load data is converted into the dynamic friction coefficient of the shifting tension wire corresponding to the same core wire slippage process.

2. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The push-pull measurement data is data formed in the same push-pull detection stroke according to the sampling order, including input push-pull measurement data and output push-pull measurement data; both input push-pull measurement data and output push-pull measurement data include push-pull load, push-pull stroke and push-pull direction, and have a common sampling order reference.

3. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The process of determining the sampling range at the input terminal includes: Read the sampling interval in the input push-pull measurement data where the push-pull stroke occurs before the change in push-pull load, and determine the idle stroke segment; Along the same push-pull direction after the idle section, read the sampling position where the push-pull load changes into the bearing capacity to determine the starting point of the bearing capacity section; The input sampling range is determined by cross-comparing the push-pull stroke advancement part after the starting point of the load-bearing section with the sampling part where the push-pull load enters the load-bearing change section.

4. The method for measuring the dynamic friction coefficient of the shift cable according to claim 3, characterized in that, The process of determining the idle segment includes: Read the continuous advance portion of the input end push-pull stroke along the same push-pull direction, and mark the sampling position where the push-pull load has not yet entered the bearing change sampling position; Connect the sampling positions according to the sampling order, and determine the idle segment based on the last sampling position before the push-pull load leaves the no-load fluctuation.

5. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The process of determining the sampling range at the output terminal includes: According to the push-pull direction corresponding to the input sampling range, read the output candidate sampling interval that is located after the starting point of the input sampling range from the output push-pull measurement data; Cross-compare the sampling portions where the push-pull load changes and the sampling portions where the push-pull stroke advances continuously within the candidate sampling interval at the output end, and retain the sampling portions that are connected in the sampling sequence between the two. The sampling range of the output end is determined by combining the position of the change in the push-pull load at the output end, the continuous advancement position of the push-pull stroke at the output end, and the path sequence of the bending path.

6. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The bending path has bending segments arranged along the push-pull direction of the core wire; the bending segment records the bending position, bending angle and bending direction; the arrangement order of the bending segments is consistent with the path order from the input end to the output end.

7. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The process of forming the load data includes: Based on the sampling position where the push-pull stroke begins to advance continuously in the sampling range of the output end, verify the candidate starting point of the load stroke in the sampling range of the input end, and determine the starting point of the load stroke. Using the starting point of the carrying stroke as the starting point of the input interception, the ending point of the interception is determined within the sampling range of the output end, and the data from both ends of the same core wire sliding process are intercepted. Based on the change in stroke difference in the double-ended data, the load portion corresponding to the change in stroke difference is separated from the double-ended data to form the load data corresponding to the relative sliding of the core wire and the bushing.

8. The method for measuring the dynamic friction coefficient of the shift cable according to claim 7, characterized in that, The process of determining the starting point of the carrying stroke includes: Read the sampling position where the push-pull stroke changes from stationary to continuous advancement within the sampling range of the output terminal, and obtain the corresponding sampling sequence; If the corresponding sampling sequence is after the starting point of the input sampling range, then the starting point of the input sampling range is determined as the starting point of the carrying stroke.

9. The method for measuring the dynamic friction coefficient of the shift cable according to claim 1, characterized in that, The conversion process of the dynamic friction coefficient of the shift cable includes: The cumulative wrap angle is determined along the push-pull direction of the core wire based on the bending angle of each bending segment in the bending path. Read the input load and output load corresponding to the same relative slip position from the load data; Based on the bending friction conversion relationship between input side load, output side load and cumulative wrap angle, the dynamic friction coefficient of the shifting wire corresponding to the slippage process of the same core wire is obtained.

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