A closed-loop fluid transmission state monitoring method based on simulation analysis

Abstract

The present application relates to fluid transmission state monitoring technical field, specifically to a kind of closed-loop fluid transmission state monitoring method based on simulation analysis, comprising: obtaining system operating state parameter, the instantaneous theoretical fluid exchange of positive displacement pump and hydraulic motor is determined;Determine the monitoring window that start-stop volume state meets preset closed condition, obtain volume gap sequence and total volume loss after fluid exchange and fluid elastic storage change of compensation auxiliary branch;According to the rotation phase of positive displacement pump and hydraulic motor, determine the target monitoring window set that meets the double-shaft phase separation condition, carry out synchronous decomposition to volume gap sequence, obtain pump synchronous volume gap component and motor synchronous volume gap component;Establish closed-loop fluid transmission simulation model and construct performance state corresponding relationship.The present application realizes closed-loop fluid transmission system volume performance state monitoring by volume state closure, volume gap representation, double-shaft phase synchronous decomposition and simulation state matching.

Description

Technical Field

[0001] This invention relates to the field of fluid transmission condition monitoring technology, specifically a closed-loop fluid transmission condition monitoring method based on simulation analysis. Background Technology

[0002] Closed-loop fluid transmission systems transmit power through positive displacement pumps, hydraulic motors, and closed-loop fluid circuits. They feature high power density, smooth transmission, and a wide adjustment range, and are widely used in drive systems of industrial equipment. However, with increasing operating time, wear and clearance changes in the internal mating parts of the positive displacement pump and hydraulic motor lead to increased internal leakage, causing changes in the system's volumetric performance. Therefore, it is necessary to monitor the operating status of the closed-loop fluid transmission system.

[0003] Existing technologies typically collect operating parameters such as pressure, flow rate, and rotational speed, and analyze system performance through parameter thresholds, volumetric efficiency, and simulation models. However, during the operation of a closed-loop fluid transmission system, externally observable parameters are affected not only by internal leakage but also by factors such as the compression and release of the working medium, exchange in auxiliary fluid branches, and changes in the operating status of pumps and motors. The fluid volume changes caused by different factors collectively affect the closed-loop circuit, causing the status information generated by component performance changes to overlap with the volume changes generated during normal operation. This makes it difficult for monitoring results based on external operating parameters to stably reflect the actual volumetric performance status of the system.

[0004] Therefore, improving the accuracy of volumetric performance status monitoring of closed-loop fluid transmission systems under operating conditions with multiple volume changes is a technical problem that needs to be solved.

[0005] To address this, a closed-loop fluid transmission state monitoring method based on simulation analysis is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a closed-loop fluid transmission state monitoring method based on simulation analysis. By performing volume state closure, volume gap characterization, biaxial phase synchronous decomposition, and simulation state matching, the volume performance state monitoring of the closed-loop fluid transmission system can be achieved.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A closed-loop fluid transmission state monitoring method based on simulation analysis includes: acquiring the operating state parameters of the closed-loop fluid transmission system, and determining the instantaneous theoretical fluid exchange volume of the positive displacement pump and the hydraulic motor based on the operating state parameters.

[0008] Based on the operating status parameters, a monitoring window is determined that meets the preset closure conditions for the start and end volume states. Based on the difference in instantaneous theoretical fluid exchange volume between the volumetric pump and the hydraulic motor within the monitoring window, after compensating for changes in the fluid exchange volume of the auxiliary branch and the fluid elastic storage, the volume gap sequence and the total volume loss are obtained.

[0009] Based on the rotation phase of the positive displacement pump and the hydraulic motor, a set of target monitoring windows that meet the dual-axis phase separation condition is determined from the monitoring window. Then, the volume gap sequence corresponding to the set of target monitoring windows is synchronously decomposed according to the rotation phase to obtain the pump synchronous volume gap component and the motor synchronous volume gap component.

[0010] A closed-loop fluid transmission simulation model was established. By changing the internal leakage parameters of the positive displacement pump and the hydraulic motor respectively, the correspondence between the total volumetric loss, the synchronous volumetric gap component of the pump and the synchronous volumetric gap component of the motor and different performance states was established. Based on the corresponding parameters obtained from actual monitoring, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and the hydraulic motor were determined.

[0011] Preferably, the operating status parameters include the pressure of the first working branch of the closed-loop fluid transmission system, the pressure of the second working branch, the rotation phase of the pump shaft of the positive displacement pump, the rotation phase of the motor shaft of the hydraulic motor, the displacement status of the positive displacement pump, the displacement status of the hydraulic motor, the temperature of the working medium, and the operating status parameters of the auxiliary branch; the operating status parameters are time-aligned according to a unified sampling time base, and a sequence of operating status parameters corresponding to each sampling time is established to determine the instantaneous theoretical fluid exchange volume, the monitoring window, and the rotation phase.

[0012] Preferably, the determination of the instantaneous theoretical fluid exchange volume includes: establishing a pump-side mapping relationship between the pump shaft rotation phase, pump displacement state, and instantaneous geometric fluid exchange volume on the pump side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the positive displacement pump; establishing a motor-side mapping relationship between the motor shaft rotation phase, motor displacement state, and instantaneous geometric fluid exchange volume on the motor side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the hydraulic motor; and obtaining the corresponding instantaneous theoretical fluid exchange volume from the pump-side mapping relationship and motor-side mapping relationship based on the pump shaft rotation phase, motor shaft rotation phase, and displacement state corresponding to each sampling time.

[0013] Preferably, the preset closure conditions include: the pressure difference of the first working branch between the start and end times of the monitoring window does not exceed a first pressure threshold, the pressure difference of the second working branch does not exceed a second pressure threshold, and the temperature difference of the working medium does not exceed a temperature threshold; identifying two sampling times that simultaneously satisfy the first pressure threshold, the second pressure threshold, and the temperature threshold from the continuous operating state parameters, and determining the continuous operating segment between the two sampling times as the monitoring window.

[0014] Preferably, obtaining the volume gap sequence includes: determining the difference between the instantaneous theoretical fluid exchange volume and the instantaneous theoretical fluid exchange volume on the pump side and the motor side at each sampling time within the monitoring window; determining the fluid exchange volume between the closed-loop main circuit and the auxiliary circuit based on the working state parameters of the oil replenishment branch, flushing branch, and overflow branch; determining the fluid elastic storage change based on the pressure change, equivalent fluid volume, and equivalent volume elastic parameters of the two working branches; compensating for the fluid exchange volume and fluid elastic storage change of the auxiliary circuit based on the difference in the instantaneous theoretical fluid exchange volume corresponding to each sampling time, obtaining the volume gap corresponding to each sampling time, forming the volume gap sequence according to the sampling time sequence, and accumulating the volume gaps within the monitoring window to obtain the total volume loss.

[0015] Preferably, the dual-axis phase separation condition includes: dividing the pump shaft rotation period and the motor shaft rotation period into multiple phase intervals; in the target monitoring window set, the same pump shaft phase interval corresponds to at least three motor shaft phase intervals, and the same motor shaft phase interval corresponds to at least three pump shaft phase intervals; filtering candidate monitoring windows according to the correspondence relationship, so that there is no fixed one-to-one correspondence between the pump shaft rotation phase and the motor shaft rotation phase in the target monitoring window set, and determining the candidate monitoring windows that satisfy the correspondence relationship as the target monitoring window set.

[0016] Preferably, the synchronous decomposition of the volume gap sequence includes: performing phase normalization and periodic synchronous superposition on the volume gap data in the target monitoring window set according to the pump shaft rotation phase to obtain the pump synchronous volume gap component corresponding to each pump shaft phase interval; performing phase normalization and periodic synchronous superposition on the volume gap data in the same target monitoring window set according to the motor shaft rotation phase to obtain the motor synchronous volume gap component corresponding to each motor shaft phase interval; and taking the volume gap data that does not maintain a synchronous relationship with the pump shaft rotation period and the motor shaft rotation period as the non-axis synchronous volume gap component.

[0017] Preferably, the closed-loop fluid transmission simulation model includes a positive displacement pump model, a hydraulic motor model, a two-working-branch model, a fluid compression model, and an auxiliary-branch model. Multiple parameter levels are set for the internal leakage parameters of the positive displacement pump and the hydraulic motor, and simulation operation data is generated at each parameter level according to the operating state corresponding to the actual monitoring. Based on the simulation operation data, a simulation monitoring window that meets the preset closure condition is determined, and the simulation volume gap sequence and the simulation total volume loss corresponding to the simulation monitoring window are obtained. The simulation volume gap sequence is synchronously decomposed according to the rotation phase of the positive displacement pump and the hydraulic motor to obtain the synchronous volume gap component of the simulation pump and the synchronous volume gap component of the simulation motor, thereby establishing a set of simulation performance state features corresponding to different internal leakage parameters. The actual total volume loss, the actual synchronous volume gap component of the pump, and the actual synchronous volume gap component of the motor obtained from actual monitoring are matched with the set of simulation performance state features. Based on the matching results, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and the hydraulic motor are determined.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention performs correlation analysis on the instantaneous theoretical fluid exchange between a positive displacement pump and a hydraulic motor within a monitoring window where the volume state meets preset closure conditions, and compensates for changes in the fluid exchange in the auxiliary branch and the fluid elastic storage. This yields a volume gap sequence and total volume loss that characterize the volume changes of the closed-loop fluid transmission system. This helps to reduce the impact of working medium compression, release, and auxiliary fluid exchange on the characterization of volume performance, enabling the obtained state parameters to more stably reflect the volume performance changes of the closed-loop fluid transmission system.

[0019] 2. This invention determines the target monitoring window set that satisfies the dual-axis phase separation condition based on the rotational phase of the positive displacement pump and the hydraulic motor, and performs synchronous decomposition on the volume gap sequence to obtain the pump synchronous volume gap component and the motor synchronous volume gap component respectively. This allows the volume change reflected in the closed loop to be characterized according to the periodic correlation with different rotating components, which is beneficial to obtaining the correlation information between volume performance changes and positive displacement pumps and hydraulic motors, and improves the pertinence of the performance status analysis of closed-loop fluid transmission systems.

[0020] 3. This invention establishes a closed-loop fluid transmission simulation model and changes the internal leakage parameters of the positive displacement pump and hydraulic motor respectively. It establishes the correspondence between the total volumetric loss, the synchronous volumetric gap component of the pump and the synchronous volumetric gap component of the motor and different performance states. Then, it uses actual monitoring parameters to perform state matching, combining physical volume change analysis with simulated performance state analysis. This helps to reduce the impact of fluctuations in a single operating parameter on the state judgment results and improves the consistency and accuracy of the volumetric performance state monitoring results of the closed-loop fluid transmission system under different operating conditions. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the overall process of the present invention. Figure 2 Flowchart for determining the monitoring window of this invention; Figure 3 Flowchart for determining the biaxial phase separation conditions of the present invention; Figure 4 This is a schematic diagram of the simultaneous decomposition of the volumetric gap in this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0023] Please see Figures 1 to 4 This invention provides a closed-loop fluid transmission state monitoring method based on simulation analysis, the technical solution of which is as follows: A closed-loop fluid transmission state monitoring method based on simulation analysis includes: acquiring the operating state parameters of the closed-loop fluid transmission system, and determining the instantaneous theoretical fluid exchange volume of the positive displacement pump and the hydraulic motor based on the operating state parameters.

[0024] Based on the operating status parameters, a monitoring window is determined that meets the preset closure conditions for the start and end volume states. Based on the difference in instantaneous theoretical fluid exchange volume between the volumetric pump and the hydraulic motor within the monitoring window, after compensating for changes in the fluid exchange volume of the auxiliary branch and the fluid elastic storage, the volume gap sequence and the total volume loss are obtained.

[0025] Based on the rotation phase of the positive displacement pump and the hydraulic motor, a set of target monitoring windows that meet the dual-axis phase separation condition is determined from the monitoring window. Then, the volume gap sequence corresponding to the set of target monitoring windows is synchronously decomposed according to the rotation phase to obtain the pump synchronous volume gap component and the motor synchronous volume gap component.

[0026] A closed-loop fluid transmission simulation model was established. By changing the internal leakage parameters of the positive displacement pump and the hydraulic motor respectively, the correspondence between the total volumetric loss, the synchronous volumetric gap component of the pump and the synchronous volumetric gap component of the motor and different performance states was established. Based on the corresponding parameters obtained from actual monitoring, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and the hydraulic motor were determined.

[0027] Example 1: This embodiment focuses on a closed-loop fluid transmission system consisting of a variable displacement pump, a hydraulic motor, a first working branch, a second working branch, a replenishment branch, a flushing branch, and an overflow branch. The volumetric performance status of the system during operation is monitored. The positive displacement pump and the hydraulic motor form a closed-loop main circuit through the first and second working branches. During monitoring, system operating status parameters are continuously acquired, and these parameters serve as the data basis for subsequently determining the instantaneous theoretical fluid exchange rate, monitoring window, volumetric gap sequence, and biaxial phase separation results.

[0028] Furthermore, the operating status parameters include the pressure of the first working branch of the closed-loop fluid transmission system, the pressure of the second working branch, the pump shaft rotation phase of the positive displacement pump, the motor shaft rotation phase of the hydraulic motor, the displacement status of the positive displacement pump, the displacement status of the hydraulic motor, the working medium temperature, and the operating status parameters of the auxiliary branch. The operating status parameters are time-aligned according to a unified sampling time base, and a sequence of operating status parameters corresponding to each sampling time is established to determine the instantaneous theoretical fluid exchange volume, monitoring window, and rotation phase.

[0029] Specifically, pressure acquisition units are respectively set in the first working branch and the second working branch to obtain the pressure of the first working branch and the second working branch; rotation phase detection units are respectively set in the positive displacement pump drive shaft and the hydraulic motor output shaft to obtain the rotation phase of the pump shaft and the rotation phase of the motor shaft. The rotation phases of the positive displacement pump and the hydraulic motor referred to in this specification and claims correspond to the rotation phase of the pump shaft of the positive displacement pump drive shaft and the rotation phase of the motor shaft of the hydraulic motor output shaft, respectively; in an unambiguous context, they can be simply referred to as the rotation phase of the positive displacement pump and the rotation phase of the hydraulic motor, respectively. The rotation phase detection unit can be implemented using an absolute encoder or an incremental encoder combined with a zero-position reference signal, and maps the detected cumulative rotation angle to a unified phase interval corresponding to a complete rotation cycle, so that the same mechanical position has a consistent phase identifier in different rotation cycles.

[0030] The displacement state of a positive displacement pump is determined based on the position parameters of its displacement adjustment mechanism. When the positive displacement pump adopts a variable displacement swashplate structure, the pump displacement state can be determined based on the swashplate angle, the displacement control mechanism displacement, or the feedback from the control actuator, combined with a pre-calibrated displacement adjustment relationship. When the hydraulic motor adopts a variable displacement structure, the motor displacement state is determined in the same way; when the hydraulic motor adopts a fixed displacement structure, its rated displacement parameter is used as the motor displacement state. Thus, the pump shaft rotation phase and the pump displacement state together characterize the current theoretical fluid exchange state of the positive displacement pump, and the motor shaft rotation phase and the motor displacement state together characterize the current theoretical fluid exchange state of the hydraulic motor.

[0031] A temperature detection unit is set in the closed-loop main circuit to obtain the working medium temperature, which can characterize the thermal state of the working medium. The working medium temperature is used to determine whether the volume states at the start and end times of the monitoring window are comparable, and to determine the equivalent volumetric elastic parameters related to the working medium state.

[0032] The operating status parameters of the auxiliary branches are used to characterize the fluid exchange status between the closed-loop main circuit and the auxiliary branches. Specifically, the replenishment branch obtains the replenishment pressure and the operating status of the replenishment valve, the flushing branch obtains the operating status of the flushing valve, and the overflow branch obtains the operating status of the overflow valve and the corresponding pressure parameters. In the subsequent volumetric gap calculation process, the fluid exchange volume between the auxiliary branches and the closed-loop main circuit is determined based on the above operating status parameters.

[0033] Since the various operational status parameters can be obtained from different detection units, their original sampling times differ. Therefore, the operational status parameters are time-aligned according to a unified sampling time base. Let the unified sampling times be as follows: The pressure of the first working branch, the pressure of the second working branch, the pump shaft rotation phase, the motor shaft rotation phase, the pump displacement status, the motor displacement status, the working medium temperature, and the auxiliary branch working status parameters are mapped to each unified sampling time. For continuously changing parameters, time alignment is performed according to the sampling period and dynamic response characteristics of the corresponding detection unit. Parameters such as pressure, rotation phase, and displacement status that change rapidly with the operating status are resampled or interpolated according to the unified sampling time base. The working medium temperature is used to characterize the thermal state of the system and can use the most recent valid temperature measurement value or the temperature value after delay correction based on the response characteristics of the temperature detection unit. When the working medium temperature change in a candidate monitoring section exceeds the change range that the temperature detection unit can reliably track after calibration, that section is not used for the preset closure condition judgment. For discrete parameters such as valve working status, the most recent valid state value before the corresponding sampling time is used for matching, thereby establishing the operating status parameter data group corresponding to each sampling time.

[0034] After time alignment, the operational status parameters are checked for validity, and data exceeding the effective range of the sensors and abnormal data that do not conform to the actual continuity of the equipment's movement are removed. For numerical jumps caused by the rotation phase spanning a complete rotation cycle, phase continuity processing is performed according to the rotation cycle. The valid operational status parameter data groups are arranged according to the sampling time sequence to form a continuous operational status parameter sequence.

[0035] Based on the aforementioned operating state parameter sequence, the instantaneous theoretical fluid exchange volume of the positive displacement pump and hydraulic motor is subsequently determined according to the pump shaft rotation phase, motor shaft rotation phase, and corresponding displacement state; the monitoring window for satisfying the preset closing conditions for the start and end volume states is determined according to the pressure of the first working branch, the pressure of the second working branch, and the temperature of the working medium; the fluid exchange volume of the auxiliary branch is determined according to the working state parameters of the auxiliary branch; simultaneously, the pump shaft rotation phase and motor shaft rotation phase are used as the phase reference for subsequent dual-axis phase separation and synchronous decomposition of the volume gap sequence.

[0036] The present invention adopts the above-mentioned method of acquiring operating status parameters and time alignment, which can establish a unified time correspondence between pressure status, pump and motor rotation status, displacement status, working medium status and auxiliary branch status. This provides a consistent data basis for instantaneous theoretical fluid exchange volume, monitoring window and subsequent volume gap analysis, and helps to reduce the impact of sampling time deviation of different data sources on the volume performance status analysis results.

[0037] Furthermore, the determination of the instantaneous theoretical fluid exchange volume includes: establishing a pump-side mapping relationship between the pump shaft rotation phase, pump displacement state, and instantaneous geometric fluid exchange volume on the pump side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the positive displacement pump; establishing a motor-side mapping relationship between the motor shaft rotation phase, motor displacement state, and instantaneous geometric fluid exchange volume on the motor side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the hydraulic motor; and obtaining the corresponding instantaneous theoretical fluid exchange volume from the pump-side mapping relationship and motor-side mapping relationship based on the pump shaft rotation phase, motor shaft rotation phase, and displacement state corresponding to each sampling time.

[0038] Specifically, the number of working chambers, effective area of ​​the working chambers, distribution position of the working chambers along the circumference of rotation, connection intervals corresponding to the distribution windows, and the correspondence between the displacement adjustment mechanism and the volume change of the working chambers are obtained in advance for the positive displacement pump. Taking an axial piston variable pump as an example, based on the number of pistons, effective area of ​​the pistons, radius of the piston distribution circle, and swashplate position, the theoretical volume change of each piston's working chamber under different pump shaft rotation phases can be determined; then, based on the distribution plate structure, the connection state between each working chamber and the first and second working branches under the corresponding rotation phases is determined.

[0039] A pump shaft rotation cycle is divided into continuous phase sampling intervals. For each pump displacement state, the theoretical volume change of all effectively connected working chambers within each phase interval is calculated, and corresponding signs are assigned according to the direction of the working medium flowing out of and into the positive displacement pump. This establishes a pump-side mapping relationship between the pump shaft rotation phase, pump displacement state, and instantaneous geometric fluid exchange rate on the pump side. The pump-side mapping relationship can be stored using a two-dimensional data table, a piecewise function, or a pre-calculated lookup table model.

[0040] Hydraulic motors establish a motor-side mapping relationship based on their structural type. Taking an axial piston hydraulic motor as an example, the theoretical volume change of each piston's working chamber under different motor shaft rotation phases is determined based on the number of pistons, effective piston area, piston distribution circle radius, and swashplate position. The connectivity between each working chamber and the first and second working branches under the corresponding rotation phases is determined based on the distribution plate structure. The theoretical volume change of the effectively connected working chambers between adjacent sampling phases is calculated and summarized in conjunction with the motor displacement status. This establishes a motor-side mapping relationship between the motor shaft rotation phase, motor displacement status, and instantaneous geometric fluid exchange volume on the motor side. For positive displacement pumps or hydraulic motors employing other volumetric structures, the geometric volume of each working chamber as the corresponding shaft rotates with the actual volumetric structure is determined, and the effective connectivity between each working chamber and the first and second working branches is determined based on the flow distribution relationship. The theoretical volume change of each effectively connected working chamber is calculated between adjacent sampling phases, and symbols are assigned according to the direction of the working medium flowing into or out of the corresponding component, and the results are summarized. This establishes a mapping relationship between the corresponding shaft rotation phase, displacement state, and instantaneous geometric fluid exchange. The instantaneous geometric fluid exchange on the pump side and the instantaneous geometric fluid exchange on the motor side, as referred to in this specification, are theoretical fluid exchange quantities calculated based on the geometric relationship, flow distribution relationship, rotation phase, and displacement state of the corresponding component's working chamber. After determining their corresponding theoretical fluid volumes according to a uniform sampling interval, they are used as the instantaneous theoretical fluid exchange quantities on the pump side and the motor side, respectively.

[0041] In this embodiment, to ensure that subsequent volumetric gap calculations have a unified dimension, the instantaneous theoretical fluid exchange volume is expressed as the theoretical fluid volume corresponding to a unified sampling interval. For the first... At each sampling time, based on the rotation phase and displacement state corresponding to that time and adjacent sampling times, the instantaneous theoretical fluid exchange rate on the pump side is determined from the pump-side mapping relationship. And determine the instantaneous theoretical fluid exchange rate on the motor side from the mapping relationship on the motor side. The correspondence can be represented as: in, This represents the pump-side mapping relationship. This is the mapping relationship on the motor side. and These are the pump shaft rotation phase and the motor shaft rotation phase, respectively. and These represent the pump displacement status and the motor displacement status, respectively. and These represent the amount of rotational phase change between adjacent sampling times.

[0042] When adjacent sampling times cross the phase boundary of a complete rotation cycle, the phase change is processed continuously according to the corresponding rotation cycle to maintain the continuity of the calculation direction and value of the instantaneous theoretical fluid exchange rate. When the displacement state changes within a sampling interval, interpolation is performed based on the displacement state at the start and end of the sampling interval, and the theoretical fluid exchange rate corresponding to that sampling interval is determined based on the interpolated displacement state.

[0043] Through the above processing, the instantaneous theoretical fluid exchange rate sequences on the pump side and the motor side, each corresponding one-to-one with the unified sampling time base, can be obtained. Subsequently, the difference between the two sequences at the same sampling time is used to characterize the instantaneous volume difference generated during the theoretical fluid transfer process in the closed-loop main circuit, and the volume gap is further determined by combining the fluid exchange rate of the auxiliary branches and the change in fluid elastic storage.

[0044] The present invention adopts the above-described implementation method to convert the geometry, displacement adjustment state and rotation phase of the positive displacement pump and hydraulic motor into a theoretical fluid exchange quantity that varies with the sampling time sequence. This enables the theoretical fluid exchange quantity to establish a time correspondence with the actual pressure, temperature and auxiliary branch state, and retains the phase characteristics generated by the periodic working chamber movement of the rotating component. This provides a unified volumetric benchmark for subsequent volumetric gap calculation and extraction of the volumetric gap components for pump synchronization and motor synchronization.

[0045] Furthermore, the preset closure conditions include: the pressure difference of the first working branch between the start and end times of the monitoring window does not exceed the first pressure threshold, the pressure difference of the second working branch does not exceed the second pressure threshold, and the temperature difference of the working medium does not exceed the temperature threshold; identifying two sampling times that simultaneously satisfy the first pressure threshold, the second pressure threshold, and the temperature threshold from the continuous operating state parameters, and determining the continuous operating segment between the two sampling times as the monitoring window.

[0046] Specifically, for any candidate initial sampling time in the sequence of running state parameters Search for candidate end sampling times from the subsequent sampling times. The pressure of the first working branch, the pressure of the second working branch, and the temperature of the working medium at the two sampling times are read respectively. The absolute values ​​of the pressure difference of the first working branch, the pressure difference of the second working branch, and the temperature difference of the working medium at the two sampling times are taken as the corresponding pressure difference of the first working branch, pressure difference of the second working branch, and temperature difference of the working medium.

[0047] The preset closure condition is: The first working branch is and The corresponding pressure difference does not exceed the first pressure threshold; The second working branch is in and The corresponding pressure difference does not exceed the second pressure threshold; Working medium in and The corresponding temperature difference does not exceed the temperature threshold.

[0048] When all three conditions above are met, and A continuous operating section between these points is defined as a monitoring window.

[0049] In this embodiment, the satisfaction of the preset closure condition for the start and end volume states means that the comparability of the volume-related states at the start and end times of the monitoring window is determined using operating state parameters related to the pressurized fluid volume state of the closed-loop main circuit, rather than requiring the directly measured geometric volume values ​​to be the same. In this embodiment, the pressure of the first working branch, the pressure of the second working branch, and the temperature of the working medium are used to characterize the volume-related states at the start and end positions of the window. In a further embodiment, the equivalent pressurized fluid volume determined by the pump shaft rotation phase, the motor shaft rotation phase, and the corresponding displacement state can be combined to further constrain the volume-related states. This ensures that the pressure states of the two working branches and the thermal state of the working medium at the start and end positions of the monitoring window have a consistent comparison benchmark. In this embodiment, the pressure of the first working branch, the pressure of the second working branch, and the temperature of the working medium are used to perform basic closure screening of candidate monitoring windows. When the influence of the geometric volume changes of the pump-side working chamber and the motor-side working chamber with the rotation phase and displacement state on the window boundary state cannot be ignored, the equivalent pressurized fluid volume at the start and end positions of the two working branches is further determined in accordance with the method described in Embodiment 2, and further screening is performed using the corresponding volume threshold to reduce the influence of the geometric volume difference of the rotating working chamber on the calculation of fluid elastic storage.

[0050] The first and second pressure thresholds are determined based on the measurement accuracy of the corresponding pressure acquisition units, the repetitive fluctuation range of the pressure in the two working branches under healthy conditions, and the allowable elastic storage conversion error for volumetric status discrimination. Specifically, pressure and working medium temperature data of the two working branches are collected under system health conditions and within the planned monitoring operating range. The fluid elastic storage change corresponding to different candidate pressure differences is calculated, and the candidate pressure differences are adjusted step by step. The maximum candidate pressure difference that does not cause the elastic storage conversion error at the start and end of the window to exceed the preset volumetric discrimination resolution is determined as the corresponding pressure threshold.

[0051] The volumetric discrimination resolution is used to limit the allowable volume conversion error at the boundary of the monitoring window and is determined based on the measurement capabilities of the monitoring link itself. Specifically, the pressure measurement uncertainty is converted into the corresponding volumetric uncertainty based on the equivalent pressurized fluid volume and equivalent volumetric elastic parameters, and the temperature measurement uncertainty is converted into the corresponding volumetric uncertainty based on the correspondence between temperature and equivalent volumetric elastic parameters. This is then combined with the volumetric measurement uncertainty corresponding to the fluid exchange volume of the auxiliary branch, and the upper limit of the resulting comprehensive volumetric uncertainty is used as the volumetric discrimination resolution. The volumetric discrimination resolution is determined by the repeatability of the measurement link under healthy conditions and is not based on the performance state to be identified or the matching results of subsequent simulation performance states. The temperature threshold is determined according to the same principle, based on the pre-calibrated correspondence between the working medium temperature and the equivalent volumetric elastic parameters, to determine the elastic storage conversion error caused by different candidate temperature differences, and the largest candidate temperature difference that meets the volumetric discrimination resolution requirement is determined as the temperature threshold. All thresholds remain consistent under the same equipment and parameter configuration.

[0052] When there are multiple sampling termination times that meet preset closure conditions in continuous operation data, a window duration range can be preset to retain only monitoring windows whose durations fall within the range. The lower limit of the window duration is used to ensure that the window contains a sufficient number of pump shaft rotation cycles and motor shaft rotation cycles, so that continuous volume gap data can be obtained subsequently; the upper limit of the window duration is used to limit the impact of long-term drift of the operating state on the comparability of the start and end states of the window.

[0053] For a given monitoring window, retain the pressure of the first working branch, the pressure of the second working branch, the pump shaft rotation phase, the motor shaft rotation phase, the pump displacement status, the motor displacement status, the working medium temperature, the working status of the auxiliary branch, and the instantaneous theoretical fluid exchange volume of the pump side and the instantaneous theoretical fluid exchange volume of the motor side, which are determined based on the pump side mapping relationship and the motor side mapping relationship, in order to form a complete monitoring data segment corresponding to the monitoring window.

[0054] The fact that the starting and ending pressures of the monitoring window meet the closure condition does not mean that the pressure inside the window remains constant; the monitoring window allows for changes in pressure, displacement, and rotational speed according to the actual working process. Simultaneously, the effectiveness of the temperature change of the working medium inside the monitoring window is checked; if the change in the working medium temperature at any sampling moment within the window relative to the window's starting moment exceeds the preset temperature fluctuation allowable range, that monitoring window will not be used for performance state matching. The temperature fluctuation allowable range is determined based on the principle that the volumetric state conversion error caused by the working medium temperature change does not exceed the aforementioned volumetric discrimination resolution. The preset closure condition defines the correspondence between the initial and ending states of the window, ensuring that the increase in elastic storage capacity due to working medium pressure within the window corresponds cumulatively to the subsequent release of elastic storage capacity, thereby providing boundary conditions for subsequent compensation of fluid elastic storage changes and calculation of the volumetric gap sequence.

[0055] This invention, through the aforementioned monitoring window determination method, can obtain comparable operating data segments of fluid volume states at the start and end points during continuous equipment operation, eliminating the need for additional shutdown detection procedures. Defining the window boundary jointly with the pressure of the two working branches and the temperature of the working medium helps reduce the impact of changes in pressure storage state and working medium thermal state on the calculation of volume loss, providing a more consistent volume state benchmark for subsequently determining the volume gap based on the difference in instantaneous theoretical fluid exchange rates.

[0056] Furthermore, obtaining the volume gap sequence includes: determining the difference between the instantaneous theoretical fluid exchange volume and the instantaneous theoretical fluid exchange volume on the pump side and the motor side at each sampling time within the monitoring window; determining the fluid exchange volume between the closed-loop main circuit and the auxiliary circuit based on the working state parameters of the oil replenishment branch, flushing branch, and overflow branch; determining the fluid elastic storage change based on the pressure change, equivalent fluid volume, and equivalent volume elastic parameters of the two working branches; compensating for the fluid exchange volume and fluid elastic storage change of the auxiliary circuit based on the difference in the instantaneous theoretical fluid exchange volume corresponding to each sampling time, obtaining the volume gap corresponding to each sampling time, forming the volume gap sequence according to the sampling time sequence, and accumulating the volume gaps within the monitoring window to obtain the total volume loss.

[0057] Specifically, for the first monitoring window At each sampling interval, the instantaneous theoretical fluid exchange rate on the pump side is obtained based on the aforementioned pump-side mapping relationship and motor-side mapping relationship. Instantaneous theoretical fluid exchange volume with motor side And determine the difference in instantaneous theoretical fluid exchange rate: in, This represents the volumetric difference between the theoretical delivery capacity of the positive displacement pump and the theoretical acceptance capacity of the hydraulic motor within the sampling interval.

[0058] The fluid exchange volume between the closed-loop main circuit and the auxiliary circuits is determined based on the operating status parameters of the replenishment branch, flushing branch, and overflow branch. To unify the calculation direction, this embodiment specifies that the fluid volume flowing into the closed-loop main circuit of the auxiliary circuit is taken as a positive value, and the fluid volume flowing out of the closed-loop main circuit is taken as a negative value. For auxiliary circuits where the flow rate detection value can be directly obtained, the fluid exchange volume of the auxiliary circuit is obtained by integrating the flow rate within the corresponding sampling interval. For auxiliary circuits without a flow rate detection unit, the corresponding flow rate can be determined based on the valve opening status, valve opening degree, and pressure difference across the valve opening, combined with the pre-calibrated valve flow characteristics, and then the fluid exchange volume within the sampling interval is calculated. The valve flow characteristics are obtained by changing the pressure difference across the valve opening degree under multiple preset valve opening degrees covering the intended monitoring operating range and measuring the corresponding actual flow rate. The corresponding data between the valve opening degree, pressure difference, and actual flow rate is stored as a lookup table relationship. When the current operating state is between adjacent calibration states, the corresponding flow rate is determined by interpolation based on adjacent calibration data, and the conversion deviation of the interpolated flow rate is checked based on the repeated calibration results. The fluid exchange volumes of each auxiliary branch are combined according to the above notation conventions to obtain the first... The fluid exchange volume of the auxiliary branch corresponding to each sampling interval .

[0059] Simultaneously, the compensation uncertainty corresponding to the fluid exchange volume of the auxiliary branch is determined. For auxiliary branches with directly installed flow detection units, the corresponding volume measurement uncertainty is determined based on the measurement accuracy and integration time of the flow detection units; for auxiliary branches where the flow rate is converted based on the valve flow characteristics, the corresponding conversion uncertainty is determined based on the deviation between the repeated calibration results of the valve flow characteristics and the actual flow rate.

[0060] Within a monitoring window, the compensation uncertainty of each auxiliary branch is cumulatively evaluated. When the uncertainty of the fluid exchange volume of an auxiliary branch reaches or exceeds the minimum volumetric characteristic difference between adjacent performance states to be distinguished, the current monitoring window is not used for performance state matching, and the flow characteristics of the auxiliary branch are recalibrated first, or recalculated using direct flow detection data.

[0061] The working medium in the closed-loop main circuit will be compressed and released due to pressure changes. Therefore, the change in fluid elastic storage is further determined based on the pressure changes in the first and second working branches.

[0062] Let the first The equivalent pressurized fluid volumes of the first and second working branches corresponding to each sampling interval are respectively and The corresponding equivalent bulk elastic parameters are Then the first The change in fluid elastic storage caused by the pressure change in the two working branches within a sampling interval can be expressed as: in, and The first The pressure of the first working branch and the pressure of the second working branch at each sampling time; This refers to the equivalent volumetric elastic parameters determined based on the current working medium temperature. The correspondence between the working medium temperature and the equivalent volumetric elastic parameters is obtained in advance through calibration. Specifically, under multiple temperature conditions covering the range to be monitored, the working medium temperature is stabilized, a known volume change is applied under a known equivalent pressurized fluid volume, and the corresponding pressure change is measured. Based on the volume change, pressure change, and equivalent pressurized fluid volume, the equivalent volumetric elastic parameters corresponding to each calibration temperature are determined and stored in a lookup table according to temperature order. When the current working medium temperature is between adjacent calibration temperatures, interpolation is used to determine the corresponding equivalent volumetric elastic parameters.

[0063] The and The volume is determined based on the fixed pipeline volume of the first and second working branches, as well as the volumes of the pump-side and motor-side working chambers currently effectively connected to the corresponding working branches. Specifically, the equivalent pressurized fluid volume determination method described in Embodiment 2 can be used to obtain the volume of the first working branch. The sampling time and the first sampling time The equivalent pressurized fluid volume corresponding to each sampling time is calculated, and the average value of the corresponding values ​​at two sampling times is taken as the equivalent pressurized fluid volume for the corresponding sampling interval.

[0064] The equivalent pressurized fluid volume mentioned above is only used to determine the compression or release of the working medium corresponding to the pressure change; the geometric volume changes of the pump-side working chamber and the motor-side working chamber caused by rotation are still characterized by the aforementioned instantaneous theoretical fluid exchange volume on the pump side and the instantaneous theoretical fluid exchange volume on the motor side, and are not calculated again in the fluid elastic storage change.

[0065] After obtaining the difference in instantaneous theoretical fluid exchange rate, the fluid exchange rate of the auxiliary branch, and the change in fluid elastic storage, volume balance is performed according to a unified fluid inflow and outflow direction to determine the first... Volume gap corresponding to each sampling interval : Among them, the fluid exchange volume of the auxiliary branch has been assigned a value according to the principle that the flow into the closed loop main circuit is positive and the flow out of the closed loop main circuit is negative. Therefore, it can uniformly characterize the impact of the oil replenishment, flushing and overflow processes on the volume change of the closed loop main circuit. When the fluid elastic storage increases, it is deducted from the theoretical volume difference. When the fluid elastic storage is released, a negative storage change is formed accordingly.

[0066] Calculate the sampling intervals within the monitoring window sequentially according to the unified sampling time sequence. This forms a volumetric gap sequence corresponding to the time sequence. The volumetric gap sequence retains the pump shaft rotation phase and motor shaft rotation phase identifiers corresponding to each sampling time, so as to facilitate subsequent synchronous decomposition according to the phase relationship between the two rotating components.

[0067] The total volume loss corresponding to each volume gap within the monitoring window is obtained by accumulating the losses. in, This refers to the number of sampling intervals included within the monitoring window. Since the start and end times of the monitoring window meet preset closure conditions, the pressure and working medium temperature at the start and end positions of the two working branches are within preset allowable ranges. Therefore, the cumulative elastic storage change of the working medium due to compression and release within the entire monitoring window is limited, which helps to ensure that the total volumetric loss reflects the actual volumetric performance change of the closed-loop fluid transmission system. The total volumetric loss referred to in this specification is a signed net volume characteristic formed by accumulating the volumetric gaps according to the aforementioned unified inflow and outflow directions. It is used to characterize the net volumetric performance change formed along the preset volumetric exchange direction within the monitoring window. The name of the loss is used to characterize the physical application of this state parameter, and its mathematical value in all transient operating states is not limited to be non-negative.

[0068] This invention incorporates the instantaneous theoretical fluid exchange difference between the positive displacement pump and the hydraulic motor, the fluid exchange caused by the auxiliary branch, and the elastic storage change in the closed-loop main circuit into a unified volume balance process. This process can obtain a volume gap sequence with a continuous sampling time sequence and a corresponding rotation phase, and further obtain the total volume loss. This provides a data basis for subsequently distinguishing the volume change components related to the rotation cycle of the positive displacement pump and the rotation cycle of the hydraulic motor, which is beneficial to improving the accuracy of the volume performance state characterization of the closed-loop fluid transmission system.

[0069] Furthermore, the dual-axis phase separation condition includes: dividing the pump shaft rotation period and the motor shaft rotation period into multiple phase intervals respectively; in the target monitoring window set, the same pump shaft phase interval corresponds to at least three motor shaft phase intervals, and the same motor shaft phase interval corresponds to at least three pump shaft phase intervals; filtering candidate monitoring windows according to the correspondence relationship, so that there is no fixed one-to-one correspondence between the pump shaft rotation phase and the motor shaft rotation phase in the target monitoring window set, and determining the candidate monitoring windows that satisfy the correspondence relationship as the target monitoring window set.

[0070] Specifically, a complete rotation cycle of the pump shaft is divided into multiple consecutive pump shaft phase intervals, and a complete rotation cycle of the motor shaft is divided into multiple consecutive motor shaft phase intervals. Each phase interval is divided at equal intervals according to the complete rotation cycle; for example, one rotation cycle can be divided into 36 phase intervals, each corresponding to a 10° mechanical angle. The number of phase intervals is predetermined based on the rotation phase detection accuracy, sampling frequency, and the phase resolution required for subsequent synchronous decomposition, and remains constant throughout the same condition monitoring process.

[0071] For each monitoring window determined according to the preset closure conditions, the pump shaft rotation phase and motor shaft rotation phase corresponding to each volume gap data are read according to a unified sampling time base, and the pump shaft phase interval and motor shaft phase interval to which it belongs are determined respectively. Thus, each volume gap data corresponds to a dual-axis phase combination determined by the pump shaft phase interval and the motor shaft phase interval.

[0072] Subsequently, the distribution of each dual-axis phase combination within the candidate monitoring window is statistically analyzed. For any pump shaft phase interval, the number of different motor shaft phase intervals that co-occur with that pump shaft phase interval is counted; for any motor shaft phase interval, the number of different pump shaft phase intervals that co-occur with that motor shaft phase interval is counted. When the same pump shaft phase interval corresponds to at least 3 motor shaft phase intervals, and the same motor shaft phase interval corresponds to at least 3 pump shaft phase intervals, the corresponding data is considered to meet the minimum requirement for dual-axis phase cross-coverage. This minimum requirement is used to reduce the cases where the pump shaft rotation phase and the motor shaft rotation phase form a fixed or approximately fixed correspondence, and serves as a data screening condition for subsequent synchronous decomposition. Data that meets the minimum requirement still needs to be processed according to the synchronous decomposition process described later, and the effectiveness of the decomposition results is evaluated based on the convergence of the synchronous components and the non-axis synchronous volume gap components.

[0073] In practical processing, when the dual-axis phase distribution within a single monitoring window cannot meet the above conditions, multiple monitoring windows with different pump-motor speed relationships or different displacement states are included in the candidate range, and filtering is performed based on the cumulative coverage of dual-axis phase combinations. Specifically, a dual-axis phase occupancy table can be established with pump shaft phase intervals as rows and motor shaft phase intervals as columns. When a dual-axis phase combination has effective volume gap data in a candidate monitoring window, the corresponding position is marked as occupied. As monitoring windows are added, the dual-axis phase occupancy table is continuously updated until each pump shaft phase interval participating in the analysis establishes a data correspondence with at least three motor shaft phase intervals, and each motor shaft phase interval participating in the analysis establishes a data correspondence with at least three pump shaft phase intervals.

[0074] Monitoring windows that meet the above conditions are determined as the target monitoring window set. Therefore, the same pump shaft phase position can correspond to multiple different rotational phases of the hydraulic motor within the target monitoring window set, and the same motor shaft phase position can also correspond to multiple different rotational phases of the positive displacement pump. This avoids the situation where the pump shaft rotational phase and the motor shaft rotational phase maintain a fixed one-to-one correspondence in the monitoring data when the positive displacement pump and hydraulic motor operate with a fixed phase relationship for a long time. This further reduces the mixing of components related to the pump shaft rotation period and components related to the motor shaft rotation period in the volumetric gap sequence due to the fixed phase correspondence.

[0075] For example, when a certain pump shaft phase interval appears simultaneously with the 5th, 16th, and 27th motor shaft phase intervals in different monitoring windows, the change in the volume gap corresponding to that pump shaft phase can be repeatedly observed under conditions where the hydraulic motor is in at least three different mechanical positions. If this change still stably appears in the same pump shaft phase interval under different motor shaft phase conditions, it can be used as a candidate change component related to the pump shaft rotation cycle, and the same logic is used for synchronous changes in the motor shaft.

[0076] The minimum requirement of at least three phase intervals is for dual-axis phase cross-coverage. This is to avoid one axis phase having only a fixed or approximately fixed correspondence with one or two phases of another axis, and to provide repeated observations under multiple different phase conditions. When the phase intervals are finely divided or the volume gap data fluctuates significantly, the actual number of cross-coverages can be increased. If the phase intervals involved in the analysis still cannot meet the minimum cross-coverage requirements within the preset candidate monitoring data range, the current data will not form a target monitoring window set, and new operating segments will be collected and re-selected. The minimum cross-coverage requirement is used to provide data conditions for cross-observation of pump shaft phase and motor shaft phase, and is not used as the sole criterion for determining the validity of the synchronous decomposition results. Whether the synchronous decomposition results are used for subsequent performance state matching is also determined according to the convergence conditions of the alternating update and the evaluation results of the non-axis synchronous volume gap components described later.

[0077] When the positive displacement pump and hydraulic motor maintain a fixed or approximately fixed simple integer speed ratio within the candidate monitoring data range for an extended period, resulting in repetitive finite phase combinations between the pump shaft phase and the motor shaft phase, and causing the dual-axis phase occupancy table to fail to meet the aforementioned cross-coverage requirements, the corresponding operating segment is determined not to meet the dual-axis phase separation condition. This operating segment is not used for synchronous decomposition, and subsequent operating segments where the pump-motor speed relationship changes are prioritized to supplement the candidate monitoring data. Even if the minimum phase cross-coverage requirement is met, if subsequent alternating synchronous decomposition fails to meet the preset convergence condition, the corresponding decomposition results are still not used for performance state matching according to the aforementioned non-convergence processing method.

[0078] After forming the target monitoring window set, the sampling time, volumetric gap value, pump shaft rotation phase, motor shaft rotation phase, and corresponding phase interval are retained for each volumetric gap data, so that the data in different monitoring windows can be rearranged according to a unified pump shaft phase reference and motor shaft phase reference. Based on the target monitoring window set, the volumetric gap sequence is subsequently synchronously decomposed according to the pump shaft rotation phase and motor shaft rotation phase respectively to obtain the pump synchronous volumetric gap component and the motor synchronous volumetric gap component.

[0079] The present invention uses the above-mentioned dual-axis phase separation condition to filter the monitoring window, which allows the phase position of the same rotating component to be repeatedly observed in multiple different phase states of another rotating component. This reduces the mixing of synchronous components caused by the fixed correspondence between the pump shaft phase and the motor shaft phase, and provides data conditions for extracting the pump rotation cycle correlation components and the motor rotation cycle correlation components from the same volume gap sequence. This is beneficial to improving the reliability of the correlation analysis between volume performance changes and different rotating components.

[0080] Furthermore, the synchronous decomposition of the volume gap sequence includes: performing phase normalization and periodic synchronous superposition on the volume gap data in the target monitoring window set according to the pump shaft rotation phase to obtain the pump synchronous volume gap component corresponding to each pump shaft phase interval; performing phase normalization and periodic synchronous superposition on the volume gap data in the same target monitoring window set according to the motor shaft rotation phase to obtain the motor synchronous volume gap component corresponding to each motor shaft phase interval; and taking the volume gap data that does not maintain a synchronous relationship with the pump shaft rotation period and the motor shaft rotation period as the non-axis synchronous volume gap component.

[0081] Specifically, the volume gap corresponding to each sampling moment in the target monitoring window set is read. Pump shaft rotation phase and motor shaft rotation phase Following the phase interval division method used in the aforementioned dual-axis phase separation process, a complete rotation cycle of the pump shaft and motor shaft is divided into the same number of phase intervals, and the rotation phases in different monitoring windows are uniformly mapped to a complete rotation cycle, so that data in the same mechanical position in each monitoring window have a consistent phase identifier.

[0082] First, pump shaft phase synchronization processing is performed. Volumetric gap data belonging to the same pump shaft phase interval within the target monitoring window set are grouped into the same data set, and corresponding data from different pump rotation cycles and different target monitoring windows are synchronously superimposed. For the first... The pump synchronization volume gap component for each pump shaft phase interval can be determined based on the statistical results of all effective volume gap data within that phase interval, for example, by using the arithmetic mean: in, This indicates that the pump shaft rotation phase is at the 1st The set of effective sampling points for each phase interval This indicates the number of valid sampling points. Indicates the first The pump synchronization volume gap component corresponds to each pump shaft phase interval. By calculating all pump shaft phase intervals sequentially, the distribution of the pump synchronization volume gap component as the pump shaft rotation phase changes is obtained.

[0083] Since the aforementioned target monitoring window set meets the minimum requirement for dual-axis phase cross-coverage, and the same pump shaft phase interval contains multiple different motor shaft phase states, when multiple rotation cycles and monitoring windows are synchronously superimposed, it is beneficial to disperse the volume changes that are related to the motor shaft rotation phase but do not maintain a fixed correspondence with the pump shaft in the pump shaft phase coordinates, and to retain the volume changes that repeatedly correspond to the pump shaft rotation cycle; on this basis, the mutual mixing of the two types of synchronization components is further reduced by subsequent alternating synchronous updates.

[0084] Subsequently, to avoid the already extracted pump synchronization volume gap component making a duplicate contribution to the extraction of the motor synchronization component, the corresponding pump synchronization volume gap component is subtracted from the original volume gap according to the pump shaft phase interval to which each sampling time belongs, forming the first remaining volume gap sequence: in, Indicates the first The pump shaft phase interval corresponding to each sampling time.

[0085] Motor shaft phase synchronization processing is performed based on the first remaining volume gap sequence. Data from the first remaining volume gap belonging to the same motor shaft phase interval are grouped into the same data set, and corresponding data from different motor rotation cycles and different target monitoring windows are synchronously superimposed. For the first... The synchronous volume gap component of the motor shaft phase interval can be expressed as: in, This indicates that the motor shaft rotation phase is at the 1st The set of effective sampling points for each phase interval Indicates the number of corresponding valid sampling points. Indicates the first The synchronous volume gap components of the motor shaft are corresponding to each motor shaft phase interval. The distribution of the synchronous volume gap components of the motor shaft as the motor shaft rotation phase changes is obtained by calculating all motor shaft phase intervals in sequence.

[0086] To further reduce the impact of the extraction order on the synchronization components, this embodiment can also perform synchronous superposition alternately according to the pump shaft phase and the motor shaft phase. That is, after obtaining the initial motor synchronization volume gap component, the motor synchronization volume gap component is subtracted from the original volume gap sequence, and then the pump synchronization volume gap component is recalculated; the above process is repeated until the changes in the pump synchronization volume gap component and the motor synchronization volume gap component obtained in two adjacent cycles are both less than a preset convergence threshold. Through this process, the related components of the two rotation cycles are gradually separated in the same volume gap sequence.

[0087] After obtaining the pump synchronization volume gap component and the motor synchronization volume gap component, the corresponding synchronization component is obtained according to the pump shaft phase interval and the motor shaft phase interval corresponding to each sampling time, and then subtracted from the original volume gap to obtain the non-shaft synchronization volume gap component: The non-shaft synchronization volume gap component is used to characterize the remaining volume change that has not established a stable synchronization relationship with the pump shaft rotation cycle and the motor shaft rotation cycle. The non-shaft synchronization volume gap component is not directly used as a feature of the internal leakage performance status matching of positive displacement pumps and hydraulic motors, but is used to evaluate the data validity of the current synchronization decomposition results and monitoring window.

[0088] A residual reference range can be established based on the amplitude or dispersion of the non-axis synchronous volume gap component obtained from repeated monitoring under healthy conditions. When the non-axis synchronous volume gap component corresponding to the current monitoring window exceeds the upper limit of the residual reference range, it is determined that the window has a strong non-axis synchronous disturbance, and the window will not be used for performance state matching. The remaining valid data are arranged according to the sampling time sequence. This forms a non-axis synchronous volume gap sequence.

[0089] Therefore, the volumetric gap in the same target monitoring window set is decomposed into a pump synchronous volumetric gap component related to the pump shaft rotation cycle, a motor synchronous volumetric gap component related to the motor shaft rotation cycle, and a non-shaft synchronous volumetric gap component. Among them, the pump synchronous volumetric gap component and the motor synchronous volumetric gap component retain their respective distribution characteristics as a function of the rotation phase, and together with the aforementioned total volumetric loss, they serve as state parameters for performance state matching in the subsequent closed-loop fluid transmission simulation model.

[0090] This invention utilizes the dual-axis phase cross-over relationship in the target monitoring window set to repeatedly observe and aggregate the volume changes related to the rotation cycle of the positive displacement pump and hydraulic motor under the corresponding rotation phase coordinates. While retaining the total volume loss information, it further forms a volume gap component with component rotation correlation, providing a state characterization basis for subsequent judgment of the correspondence between the volume performance changes of the closed-loop fluid transmission system and the positive displacement pump and hydraulic motor.

[0091] Furthermore, the closed-loop fluid transmission simulation model includes a positive displacement pump model, a hydraulic motor model, a two-working-branch model, a fluid compression model, and an auxiliary-branch model. Multiple parameter levels are set for the internal leakage parameters of the positive displacement pump and the hydraulic motor, and simulation operation data is generated at each parameter level according to the operating state corresponding to the actual monitoring. Based on the simulation operation data, a simulation monitoring window that satisfies the preset closure condition is determined, and the simulation volume gap sequence and the simulation total volume loss corresponding to the simulation monitoring window are obtained. The simulation volume gap sequence is synchronously decomposed according to the rotational phase of the positive displacement pump and the hydraulic motor to obtain the synchronous volume gap component of the simulation pump and the synchronous volume gap component of the simulation motor, thereby establishing a set of simulation performance state features corresponding to different internal leakage parameters. The actual total volume loss, the actual synchronous volume gap component of the pump, and the actual synchronous volume gap component of the motor obtained from actual monitoring are matched with the set of simulation performance state features. Based on the matching results, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and the hydraulic motor are determined.

[0092] Specifically, the closed-loop fluid transmission simulation model includes a positive displacement pump model, a hydraulic motor model, working branch models corresponding to the first and second working branches, a fluid compression model, and an auxiliary branch model. The positive displacement pump model and the hydraulic motor model at least include displacement adjustment, changes in the volume of the rotating working chamber, and internal leakage characteristics; the working branch model is established based on the pipe length, pipe diameter, and equivalent fluid volume of the actual system; the fluid compression model describes the changes in fluid elastic storage caused by pressure changes based on the equivalent volumetric elastic parameters of the working medium; the auxiliary branch model includes the oil replenishment branch, flushing branch, and overflow branch corresponding to the actual system, used to simulate the fluid exchange between the closed-loop main loop and the auxiliary branches.

[0093] During the simulation, the pressures of the first and second working branches are used as the state variables of the working branches. For any working branch... The net inflow fluid volume is determined based on the fluid exchange between the volumetric pump, hydraulic motor, auxiliary branch, and internal leakage and the working branch at the current time step. Update the working branch pressure according to the following formula: in, The equivalent pressurized fluid volume of the working branch corresponding to the current time step, in cubic meters. 3 ; For the corresponding equivalent bulk elastic parameters, the unit is Pa; The net inflow volume is defined as positive for inflow and negative for outflow, expressed in cubic meters (m³). 3 .

[0094] After the simulation model is established, the basic parameters of the model are first set using the equipment structural parameters and the measured operating parameters under healthy operating conditions. Among them, the pipe length, pipe diameter, fixed volume, working chamber geometry, flow distribution relationship and discharge adjustment relationship that can be directly determined by the equipment structure are used as fixed basic parameters and are not involved in the healthy state fitting adjustment; the equivalent volume elastic parameters, auxiliary branch flow characteristics and equivalent model parameters that cannot be directly determined by the structural parameters are used as parameters to be corrected.

[0095] The displacement, speed, pressure of the two working branches, working medium temperature, and auxiliary branch status of the positive displacement pump and hydraulic motor under healthy conditions are input into the simulation model, and the simulation model output is quantitatively verified. The verification includes at least the pressure curve error of the first working branch, the pressure curve error of the second working branch, the total volumetric loss error under healthy conditions, the phase distribution error of the pump synchronous volumetric notch component, and the phase distribution error of the motor synchronous volumetric notch component. The pressure curve error is evaluated using the root mean square error between the simulated value and the measured value under a unified sampling time base. The total volumetric loss is evaluated using the relative deviation between the simulated value and the measured value. The phase distribution errors of the pump synchronous volumetric notch component and the motor synchronous volumetric notch component are evaluated using the root mean square error of the difference between the simulated value and the measured value in the corresponding phase interval.

[0096] The permissible error for each verification index is determined based on the corresponding measurement link uncertainty, the fluctuation range of repeated health status monitoring, and the feature resolution required for subsequent performance status matching. When any verification index exceeds the corresponding permissible error, in each round, the type of parameter to be corrected that is directly related to the index that exceeds the error is adjusted first, while keeping the fixed basic parameters determined by the equipment structure and other parameters that have been corrected unchanged. Then, all verifications are re-executed. Only after all verification indices simultaneously meet the corresponding permissible errors are the current model parameters fixed, and a set of simulation performance status features corresponding to different internal leakage parameters is generated.

[0097] Based on this, multiple parameter levels are set for the internal leakage parameters of the positive displacement pump and the hydraulic motor, respectively. The internal leakage parameters characterize the equivalent leakage capacity formed by changes in the internal clearance of the corresponding components, and serve as an equivalent proportional parameter between the internal leakage flow rate and the pressure difference across the corresponding leakage channel in the simulation model. For simulation implementations using an equivalent linear leakage relationship, within the performance range to be monitored, the equivalent linear leakage relationship is first verified using measured data or model calibration results under healthy conditions and different leakage capacity states; only when the relevant calibration error does not exceed the preset model allowable error, the internal leakage flow rate of the positive displacement pump or hydraulic motor is determined according to the following formula: in, Internal leakage flow rate, in m³ / s. 3 / s; The pressure difference between the two ends of the corresponding internal leakage channel, in Pa; Internal leakage parameters determined at the reference working medium temperature, in meters. 3 / (s·Pa); The dynamic viscosity of the working medium at the reference temperature. This represents the dynamic viscosity at the current working medium temperature, with units of Pa·s. The relationship between working medium temperature and dynamic viscosity is determined based on the known properties of the working medium or pre-calibration results.

[0098] The internal leakage parameters are determined based on measured operating data under healthy conditions, and candidate parameter values ​​are sequentially set from the benchmark value in the direction of increasing internal leakage capacity. For each newly added candidate parameter value, a corresponding simulation performance state characteristic is generated according to the aforementioned simulation processing flow, and the normalized characteristic difference between it and the simulation performance state characteristic corresponding to the previously retained parameter level is calculated. When the normalized characteristic difference is greater than the upper limit of the characteristic difference jointly determined by the repeated monitoring fluctuations under healthy conditions, the comprehensive uncertainty of the measurement link, and the verification error of the simulation model, the candidate parameter value is retained as the next internal leakage parameter level; otherwise, the candidate internal leakage parameter continues to increase until the above conditions are met. Multiple internal leakage parameter levels are formed sequentially in this manner. Different internal leakage parameter levels correspond to different equivalent leakage capacity states caused by changes in internal fit clearance, used to characterize the degree of change in the volumetric performance of the corresponding component, rather than directly equating the internal leakage parameter to the specific geometric wear size. When setting the internal leakage parameter level of the positive displacement pump, the internal leakage parameter of the hydraulic motor and other model parameters remain unchanged; when setting the internal leakage parameter level of the hydraulic motor, the internal leakage parameter of the positive displacement pump and other model parameters remain unchanged. This allows us to obtain simulation state data corresponding to changes in pump-side performance and motor-side performance, respectively. We can also set parameter combinations where the internal leakage parameters of the positive displacement pump and hydraulic motor change simultaneously, to characterize the system state when both undergo simultaneous volumetric performance changes.

[0099] For each internal leakage parameter level, the simulation model is driven by the operating state corresponding to the actual monitoring. Specifically, the pump displacement state, motor displacement state, drive speed, load state, and working medium temperature corresponding to the actual monitoring process can be used as simulation boundary conditions. This ensures that the simulation results for different internal leakage parameters have a consistent operating state basis with the actual monitoring data, thereby reducing the impact of differences in operating conditions on subsequent state matching.

[0100] The simulation operation data is processed using the same procedure as the actual monitoring data. First, based on the pressure of the first working branch, the pressure of the second working branch, and the temperature of the working medium obtained from the simulation, the simulation monitoring window that satisfies the preset closure condition for the start and end volume states is determined. Based on the difference between the instantaneous theoretical fluid exchange rates of the volumetric pump and the hydraulic motor within the simulation monitoring window, and by compensating for the changes in the fluid exchange rate and fluid elastic storage of the simulation auxiliary branch, the simulation volume gap sequence and the total simulation volume loss are obtained.

[0101] Furthermore, based on the pump shaft rotation phase and motor shaft rotation phase in the simulation data, the simulation volume gap sequence corresponding to the simulation monitoring window that satisfies the dual-axis phase separation condition is synchronously decomposed to obtain the synchronous volume gap components of the simulated pump and the synchronous volume gap components of the simulated motor. This ensures that the simulation side and the actual monitoring side use the same volume state closure conditions, volume gap construction methods, and dual-axis synchronous decomposition methods, guaranteeing that the state parameters formed by the two types of data have a corresponding relationship.

[0102] For each internal leakage parameter level, the corresponding simulated total volumetric loss, the simulated pump synchronous volumetric gap component, and the simulated motor synchronous volumetric gap component are combined to form a set of simulated performance state features. The pump synchronous volumetric gap component and the motor synchronous volumetric gap component can be arranged according to pre-defined rotational phase intervals to preserve their distribution information as a function of the rotational phase. The simulated performance state features corresponding to each internal leakage parameter level are stored according to the parameter level, thus forming a set of simulated performance state features. The correlation between each simulated performance state feature and the corresponding positive displacement pump internal leakage parameter and hydraulic motor internal leakage parameter is then established.

[0103] During actual condition monitoring, the total volumetric loss, pump synchronous volumetric deficit component, and motor synchronous volumetric deficit component obtained from actual monitoring are organized into actual performance state features using the same feature organization method as the simulation data. These features are then matched with each simulation performance state feature in the simulation performance state feature set. During the matching process, a health state reference scale is pre-determined based on the state parameters obtained from repeated monitoring under healthy conditions. For any state parameter in the state feature sequence, the root mean square (RMS) of that state parameter obtained from repeated monitoring under healthy conditions is used as the corresponding health state reference scale. When the RMS is less than the measurement uncertainty conversion value corresponding to that state parameter, the measurement uncertainty conversion value is used as the health state reference scale to avoid abnormal amplification of the normalization result due to the reference scale approaching zero.

[0104] The same state parameter in both actual and simulated performance state characteristics is normalized using the same health state reference scale. Let the th state parameter in the state characteristic sequence be... The health status reference scale for each state parameter is: Then the normalized corresponding state parameters are: The health state reference scale and the corresponding state parameters have the same dimensions; therefore, the normalized state parameters are dimensionless. After normalization, the feature differences between the actual performance state characteristics and each simulated performance state characteristic are calculated.

[0105] For example, the total volumetric loss, the pump synchronous volumetric gap component corresponding to each pump shaft phase interval, and the motor synchronous volumetric gap component corresponding to each motor shaft phase interval can be sequentially composed into a state feature sequence. The distance between the actual state feature sequence and each simulated state feature sequence is calculated, and the simulated performance state with the smallest distance and satisfying a preset matching threshold is taken as the performance state corresponding to the current actual system. The preset matching threshold is determined based on the normalized feature difference fluctuation range between the actual performance state characteristics formed by repeated monitoring under healthy conditions and the corresponding healthy simulated performance state characteristics, and is included in the health state verification error of the simulation model, so that the feature differences formed within the repeated health fluctuations and the allowable error range of the model are not judged as performance state changes.

[0106] When the matching result mainly corresponds to the simulated performance state characteristics formed by the change of internal leakage parameters of the positive displacement pump, and the synchronous volumetric gap component of the pump shows a change consistent with the corresponding simulation result, a correspondence is established between the current volumetric performance change and the positive displacement pump; when the matching result mainly corresponds to the simulated performance state characteristics formed by the change of internal leakage parameters of the hydraulic motor, and the synchronous volumetric gap component of the motor shows a change consistent with the corresponding simulation result, a correspondence is established between the current volumetric performance change and the hydraulic motor; when the actual state characteristics match the simulated performance state characteristics of simultaneous changes in internal leakage parameters on both the pump and motor sides, it is determined that both the positive displacement pump and the hydraulic motor have a correspondence with the current volumetric performance change.

[0107] Through the above-described embodiments, this invention establishes a correspondence between the total volumetric loss and the dual-axis synchronous volumetric gap component generated by actual monitoring and the simulated performance state with clearly defined internal leakage parameters. While using the total volumetric loss to reflect the overall volumetric performance change of the system, it combines the pump synchronization and motor synchronization volumetric gap components to determine the correlation between performance changes and corresponding rotating components, which is beneficial to improving the accuracy of volumetric performance state monitoring and correlation analysis of closed-loop fluid transmission systems.

[0108] This invention performs correlation analysis on the instantaneous theoretical fluid exchange between a positive displacement pump and a hydraulic motor within a monitoring window where the initial and final volume states meet preset closure conditions. It also compensates for changes in auxiliary branch fluid exchange and fluid elastic storage, obtaining a volume gap sequence and total volume loss. This allows volume changes during system operation to be characterized by a unified volume balance relationship. Furthermore, it utilizes the rotational phase of the positive displacement pump and hydraulic motor to synchronously decompose the volume gap sequence, obtaining synchronous volume gap components for the pump and motor. These components are then matched with simulated performance states corresponding to different internal leakage parameters. This provides information reflecting the overall volumetric performance changes of the closed-loop fluid transmission system, and establishes a correlation between performance changes and the positive displacement pump and hydraulic motor. This helps reduce the impact of auxiliary fluid exchange, fluid compression states, and the combined effects of different rotating components on state characterization, improving the accuracy and relevance of volumetric performance state monitoring for closed-loop fluid transmission systems.

[0109] Example 2: Furthermore, the preset closure condition also includes an equivalent pressurized volume closure condition; based on the rotation phase of the positive displacement pump, the rotation phase of the hydraulic motor, the displacement state of the positive displacement pump, and the displacement state of the hydraulic motor corresponding to the start and end times of the monitoring window, the equivalent pressurized fluid volumes of the first working branch and the second working branch at the start and end times are determined respectively; the difference in equivalent pressurized fluid volume between the start and end of the first working branch and the difference in equivalent pressurized fluid volume between the start and end of the second working branch are calculated; when the difference in equivalent pressurized fluid volume between the start and end of the first working branch does not exceed the first volume threshold, the difference in equivalent pressurized fluid volume between the start and end of the second working branch does not exceed the second volume threshold, and the first pressure threshold, the second pressure threshold, and the temperature threshold are satisfied simultaneously, the corresponding continuous operating segment is determined as the monitoring window.

[0110] Specifically, based on the number of working chambers, geometric dimensions of the working chambers, flow distribution relationships, and displacement adjustment relationships of the positive displacement pump and hydraulic motor, the geometric volume of each working chamber and its connectivity with the first and second working branches are determined in advance under different rotation phases and displacement states. For the start time of any candidate monitoring window... and end time The corresponding pump shaft rotation phase, motor shaft rotation phase, pump displacement state, and motor displacement state are read respectively, and the volumes of the pump-side and motor-side working chambers at each moment are determined according to the aforementioned working chamber geometry. For the first working branch, the fixed volume of the pipeline of the first working branch, as well as the volumes of the pump-side and motor-side working chambers currently connected to the first working branch, are combined to obtain the equivalent pressurized fluid volume corresponding to the first working branch. This can be expressed as: in, For a moment The equivalent pressurized fluid volume of the first working branch This refers to the fluid volume corresponding to the pipeline and fixed connection cavity in the first working branch. and The first The pump-side working chamber and the first The motor-side working chamber at time Geometric volume; and The effective connectivity coefficient, determined based on the flow distribution relationship, is set to 1 when the working chamber is connected to the first working branch and 0 when they are not connected. For the working chamber in the flow distribution transition zone, the corresponding intermediate value can be determined based on the effective connectivity of the flow distribution window. The equivalent pressurized fluid volume of the second working branch... The equivalent pressurized fluid volume is determined in the same manner. Besides being used to determine the closed state of the equivalent pressurized fluid volume at the start and end positions of the monitoring window, the equivalent pressurized fluid volume for each sampling interval can also be determined according to the corresponding values ​​of adjacent sampling times, and used for calculating the change in fluid elastic storage as described in Example 1, so that the pressurized fluid volume used in the elastic storage calculation corresponds to the pump shaft rotation phase, motor shaft rotation phase, and displacement state. The difference in equivalent pressurized fluid volume corresponding to the start and end times of the candidate monitoring window is calculated respectively: when Not exceeding the first volume threshold If the pressure difference between the first and second working branches at the start and end positions of the window does not exceed the second volume threshold, and the pressure difference between the first and second working branches and the temperature difference of the working medium simultaneously meet the aforementioned corresponding thresholds, then... and The continuous operating section between these points is defined as the monitoring window. The first and second volume thresholds can be predetermined based on the calculation error of the equipment structural parameters, the fluctuation range of the equivalent pressurized fluid volume obtained from repeated monitoring under healthy conditions, and the allowable deviation in the calculation of fluid elastic reserves. Consistent judgment criteria are used during the condition monitoring of the same equipment.

[0111] This invention, based on the closed-loop pressure and working medium temperature of the two working branches, further utilizes the pump and motor rotation phase and displacement status to define the equivalent pressurized fluid volume at the start and end positions of the monitoring window. This provides a more consistent basis for comparison in terms of pressure, thermal, and pressurized fluid geometric volume at both ends of the monitoring window. This helps to reduce the inclusion of elastic storage differences caused by changes in the volume of the rotating working chamber in the volume gap, and improves the accuracy of the total volume loss in characterizing the actual volume performance changes of the system.

[0112] Further, after obtaining the initial pump synchronization volume gap component and the initial motor synchronization volume gap component, the current motor synchronization volume gap component is subtracted from the volume gap sequence, and the pump synchronization volume gap component is re-determined according to the pump shaft rotation phase; then, the updated pump synchronization volume gap component is subtracted from the volume gap sequence, and the motor synchronization volume gap component is re-determined according to the motor shaft rotation phase; the updating of the pump synchronization volume gap component and the motor synchronization volume gap component is performed alternately until the change in the pump synchronization volume gap component obtained from two adjacent updates does not exceed the first convergence threshold, and the change in the motor synchronization volume gap component does not exceed the second convergence threshold. The pump synchronization volume gap component and the motor synchronization volume gap component when the convergence condition is met are taken as the synchronization decomposition result.

[0113] Specifically, the pump synchronization volume gap component and the motor synchronization volume gap component obtained from the aforementioned synchronization decomposition are used as the initial synchronization components. Let the first... The first update The pump synchronization volume gap component corresponding to each pump shaft phase interval is: , No. The motor synchronization volume gap component corresponding to each motor shaft phase interval is: When updating the pump synchronization volume gap component, according to the first... The motor shaft phase interval corresponding to each sampling moment, from the original volume gap Subtract the current motor synchronization volume gap component, and then re-synchronize the remaining volume gap according to the pump shaft phase interval: in, This indicates that the pump shaft rotation phase is at the 1st The set of effective sampling points for each pump shaft phase interval To correspond to the number of valid sampling points, Indicates the first The sampling time corresponds to the motor shaft phase interval. Subsequently, the pump synchronization volume gap component obtained in this update is subtracted from the original volume gap sequence, and periodic synchronization is re-superimposed according to the motor shaft phase to obtain: To prevent the overall volume bias, which is independent of the rotation phase, from being arbitrarily assigned to the pump synchronization volume gap component or the motor synchronization volume gap component, the synchronization component is weighted and zero-mean normalized after each update of the corresponding synchronization component.

[0114] No. The weighted average of the pump synchronization volume gap components obtained from the next update is: And in accordance with: The synchronization components of each pump shaft phase interval are corrected.

[0115] The synchronous volume gap component of the motor is handled in the same way: This allows the pump synchronization volume gap component and the motor synchronization volume gap component to primarily characterize the periodic volume change with the corresponding rotation phase, while the overall volume loss, independent of the rotation phase, is still characterized by the total volume loss. After completing the above normalization, the maximum change in two adjacent synchronization components is calculated and judged according to the aforementioned convergence criteria.

[0116] After completing one update of the pump synchronization component and the motor synchronization component, calculate the maximum change between two consecutive update results: when It does not exceed the first convergence threshold, and Updates cease when the second convergence threshold is not exceeded, and the current pump synchronization volume gap component and motor synchronization volume gap component are used as the final synchronization decomposition result. The first and second convergence thresholds are determined based on the repeated fluctuation range of the corresponding synchronization volume gap component obtained from multiple repeated monitoring under healthy conditions, and are kept consistent under the same equipment and the same phase interval configuration.

[0117] Alternating updates are performed while setting a maximum number of iterations, which is pre-determined based on the number of iterations required to normally complete the synchronization decomposition from offline healthy operating data. If the first and second convergence thresholds are not simultaneously met even after reaching the maximum number of iterations, or if the change in the synchronization component shows a continuous increase or periodic repetition and fails to enter the convergence range, the current synchronization decomposition is determined to be unconverged. The decomposition result is not used for performance status matching, and the process returns to the target monitoring window's filtering step to supplement monitoring data that meets the dual-axis phase separation condition. Only for the two types of synchronization components that have reached the convergence condition, the non-axis synchronization volume gap component is further calculated.

[0118] This invention alternately subtracts and updates the pump synchronous volume gap component and the motor synchronous volume gap component in the same volume gap sequence, so that the periodic volume change corresponding to one rotating component is gradually weakened in the calculation process of the synchronous component of another rotating component. The change in synchronous component is used as the convergence criterion, which helps to reduce the mutual mixing of the two rotational periodic related components under limited monitoring data, and makes the pump synchronous and motor synchronous volume gap components have a more stable component rotation correlation.

[0119] Furthermore, at least two sets of actual monitoring data with different combinations of operating state parameters are identified from the actual monitoring data, and the total volumetric loss, pump synchronous volumetric gap component, and motor synchronous volumetric gap component corresponding to each actual monitoring data set are obtained respectively. For each actual monitoring data set, the same set of internal leakage parameters of the positive displacement pump and internal leakage parameters of the hydraulic motor are used in the closed-loop fluid transmission simulation model, and the simulation operating conditions are set according to the operating state parameters of the corresponding actual monitoring data set. The simulated total volumetric loss, simulated pump synchronous volumetric gap component, and simulated motor synchronous volumetric gap component under each operating state are obtained respectively. When the simulation results corresponding to the same set of internal leakage parameters of the positive displacement pump and internal leakage parameters of the hydraulic motor meet the corresponding matching conditions under the at least two operating states, the performance state corresponding to the set of internal leakage parameters is determined as the performance state of the closed-loop fluid transmission system.

[0120] Specifically, select from actual monitoring data The actual monitoring data sets with different combinations of group operating status parameters, among which Each actual monitoring data set was processed according to the aforementioned volumetric state closure, volumetric gap calculation, and dual-axis synchronous decomposition process to obtain the corresponding actual total volumetric loss, actual pump synchronous volumetric gap component, and actual motor synchronous volumetric gap component. Different actual monitoring data sets may differ in at least one of the following: pump displacement state, motor displacement state, drive speed, load state, and working medium temperature. The first... The total volumetric loss corresponding to each actual monitoring data set, the pump synchronization volume gap component corresponding to each pump shaft phase interval, and the motor synchronization volume gap component corresponding to each motor shaft phase interval are arranged in a fixed order to form an actual performance state characteristic sequence. This sequence is then normalized using the aforementioned health state reference scale to obtain the actual performance state characteristics. In the closed-loop fluid transmission simulation model, the first... Internal leakage parameters of positive displacement pump and internal leakage parameters of hydraulic motors In the context of the aforementioned When simulating each operating state, the internal leakage parameters of that group are kept constant, and the simulation operating conditions are set according to the pump displacement state, motor displacement state, drive speed, load state, and working medium temperature corresponding to each actual monitoring data group. The simulation data obtained under each operating state are processed in the same way as the actual data to obtain the simulated total volumetric loss, the simulated pump synchronous volumetric deficit component, and the simulated motor synchronous volumetric deficit component, and then arranged and normalized in the same way as the actual performance state characteristics to form the simulated performance state characteristics. For the first Each operating state can be matched based on the distance between the actual performance state characteristics and the simulated performance state characteristics. For example: in, This refers to the number of state parameters included in the performance state characteristics. When the same set of internal leakage parameters corresponds to... In all of the selections If the performance state corresponding to each set of internal leakage parameters does not exceed the corresponding preset matching threshold under all operating states, the performance state is determined as a candidate performance state. When there are more than two sets of candidate performance states, the joint matching difference of the same set of internal leakage parameters under multiple operating states is further calculated: When there are two or more candidate performance states, they are sorted in ascending order of joint matching difference. If the difference between the smallest and second smallest joint matching difference exceeds a preset distinction threshold, the performance state corresponding to the internal leakage parameter combination with the smallest joint matching difference is determined as the performance state of the closed-loop fluid transmission system. Furthermore, the correspondence between the performance state and at least one of the positive displacement pump and hydraulic motor is determined based on the changes in the internal leakage parameters of the positive displacement pump and the hydraulic motor.

[0121] If the difference between the smallest and second smallest joint matching differences does not exceed the preset discrimination threshold, the current monitoring data is deemed insufficient to uniquely determine the combination of internal leakage parameters. Therefore, no unique component attribution result is output, and at least one set of monitoring data is added that differs from the existing monitoring data set in at least one of the following: pump displacement state, motor displacement state, drive speed, load state, or working medium temperature. Joint matching is then performed again. The preset discrimination threshold is determined based on the fluctuation range of joint matching differences obtained from repeated monitoring under healthy conditions and is included in the simulation model verification error. When the difference in joint matching differences between the optimal candidate state and the second-best candidate state does not exceed this range, no unique component attribution result is output.

[0122] This invention maintains the same set of internal leakage parameters for pumps and motors unchanged during simulations of multiple operating states, and requires that the set of internal leakage parameters meet the matching conditions of actual monitoring characteristics under different operating states. This enables different operating conditions to form common constraints on the same physical performance state, which helps to eliminate the parameter equivalence situation formed by a certain combination of internal leakage parameters producing similar monitoring characteristics only under a single operating state. This improves the stability of the correspondence between simulated performance state and actual component volumetric performance, as well as the consistency of performance state monitoring results.

[0123] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A closed-loop fluid transmission state monitoring method based on simulation analysis, characterized in that, include: Obtain the operating status parameters of the closed-loop fluid transmission system, and determine the instantaneous theoretical fluid exchange rate of the positive displacement pump and hydraulic motor based on the operating status parameters; The monitoring window that meets the preset closure condition for the start and end volume states is determined based on the operating status parameters. Based on the difference in instantaneous theoretical fluid exchange volume between the volumetric pump and the hydraulic motor within the monitoring window, the volume gap sequence and total volume loss are obtained after compensating for the changes in fluid exchange volume and fluid elastic storage in the auxiliary branch. Based on the rotation phase of the positive displacement pump and the hydraulic motor, a set of target monitoring windows that meet the dual-axis phase separation condition is determined from the monitoring window. The volume gap sequence corresponding to the set of target monitoring windows is synchronously decomposed according to the rotation phase to obtain the pump synchronous volume gap component and the motor synchronous volume gap component. A closed-loop fluid transmission simulation model was established. By changing the internal leakage parameters of the positive displacement pump and the hydraulic motor respectively, the correspondence between the total volumetric loss, the synchronous volumetric gap component of the pump and the synchronous volumetric gap component of the motor and different performance states was established. Based on the corresponding parameters obtained from actual monitoring, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and the hydraulic motor were determined.

2. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 1, characterized in that, The operating status parameters include the pressure of the first working branch of the closed-loop fluid transmission system, the pressure of the second working branch, the rotation phase of the pump shaft of the positive displacement pump, the rotation phase of the motor shaft of the hydraulic motor, the displacement status of the positive displacement pump, the displacement status of the hydraulic motor, the temperature of the working medium, and the operating status parameters of the auxiliary branch. The operating status parameters are time-aligned according to a unified sampling time base, and a sequence of operating status parameters corresponding to each sampling time is established to determine the instantaneous theoretical fluid exchange volume, the monitoring window, and the rotation phase.

3. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 2, characterized in that, The determination of the instantaneous theoretical fluid exchange volume includes: establishing a pump-side mapping relationship between the pump shaft rotation phase, pump displacement state, and instantaneous geometric fluid exchange volume on the pump side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the positive displacement pump; establishing a motor-side mapping relationship between the motor shaft rotation phase, motor displacement state, and instantaneous geometric fluid exchange volume on the motor side based on the number of working chambers, working chamber geometry, flow distribution relationship, and displacement adjustment relationship of the hydraulic motor; and obtaining the corresponding instantaneous theoretical fluid exchange volume from the pump-side mapping relationship and motor-side mapping relationship based on the pump shaft rotation phase, motor shaft rotation phase, and displacement state corresponding to each sampling time.

4. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 3, characterized in that, The preset closure conditions include: the pressure difference of the first working branch between the start and end times of the monitoring window does not exceed the first pressure threshold, the pressure difference of the second working branch does not exceed the second pressure threshold, and the temperature difference of the working medium does not exceed the temperature threshold; two sampling times that simultaneously satisfy the first pressure threshold, the second pressure threshold, and the temperature threshold are identified from the continuous operating status parameters, and the continuous operating segment between the two sampling times is determined as the monitoring window.

5. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 4, characterized in that, The volume gap sequence is obtained by: determining the difference between the instantaneous theoretical fluid exchange volume and the instantaneous theoretical fluid exchange volume on the pump side and the motor side at each sampling time within the monitoring window; determining the fluid exchange volume between the closed-loop main circuit and the auxiliary circuit based on the working state parameters of the oil replenishment branch, flushing branch, and overflow branch; determining the fluid elastic storage change based on the pressure change, equivalent fluid volume, and equivalent volume elastic parameters of the two working branches; compensating for the fluid exchange volume and fluid elastic storage change of the auxiliary circuit based on the difference in the instantaneous theoretical fluid exchange volume at each sampling time, obtaining the volume gap corresponding to each sampling time, forming the volume gap sequence according to the sampling time sequence, and accumulating the volume gaps within the monitoring window to obtain the total volume loss.

6. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 5, characterized in that, The dual-axis phase separation condition includes: dividing the pump shaft rotation period and the motor shaft rotation period into multiple phase intervals; in the target monitoring window set, the same pump shaft phase interval corresponds to at least three motor shaft phase intervals, and the same motor shaft phase interval corresponds to at least three pump shaft phase intervals; filtering candidate monitoring windows according to the correspondence relationship, so that there is no fixed one-to-one correspondence between the pump shaft rotation phase and the motor shaft rotation phase in the target monitoring window set, and determining the candidate monitoring windows that satisfy the correspondence relationship as the target monitoring window set.

7. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 6, characterized in that, The synchronous decomposition of the volume gap sequence includes: performing phase normalization and periodic synchronous superposition on the volume gap data in the target monitoring window set according to the pump shaft rotation phase to obtain the pump synchronous volume gap component corresponding to each pump shaft phase interval; performing phase normalization and periodic synchronous superposition on the volume gap data in the same target monitoring window set according to the motor shaft rotation phase to obtain the motor synchronous volume gap component corresponding to each motor shaft phase interval; and taking the volume gap data that does not maintain a synchronous relationship with the pump shaft rotation period and the motor shaft rotation period as the non-shaft synchronous volume gap component.

8. The closed-loop fluid transmission state monitoring method based on simulation analysis according to claim 7, characterized in that, The closed-loop fluid transmission simulation model includes a positive displacement pump model, a hydraulic motor model, a two-working-branch model, a fluid compression model, and an auxiliary-branch model. Multiple parameter levels are set for the internal leakage parameters of the positive displacement pump and the hydraulic motor, and simulation operation data is generated at each parameter level according to the operating state corresponding to the actual monitoring. Based on the simulation operation data, a simulation monitoring window that meets the preset closure condition is determined, and the simulation volume gap sequence and total simulation volume loss corresponding to the simulation monitoring window are obtained. The simulation volume gap sequence is then synchronously decomposed according to the rotational phase of the positive displacement pump and the hydraulic motor to obtain the synchronous volume gap component of the simulation pump and the synchronous volume gap component of the simulation motor, thereby establishing a set of simulation performance state characteristics corresponding to different internal leakage parameters. The actual total volumetric loss, the actual pump synchronous volumetric gap component, and the actual motor synchronous volumetric gap component obtained from actual monitoring are matched with the set of simulated performance state characteristics. Based on the matching results, the performance state of the closed-loop fluid transmission system and its correspondence with at least one of the positive displacement pump and hydraulic motor are determined.

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