A diesel rocker arm phase drift compensation system

Abstract

The present application relates to diesel engine valve timing technology field, disclose a kind of diesel engine rocker phase shift compensation system, including data acquisition unit, isothermal reference matching unit, displacement layer construction unit, bidirectional equal displacement phase band extraction unit, phase shift separation unit, compensation command generation unit and execution control unit.Data acquisition unit obtains crank angle, rocker displacement, cylinder head temperature, engine speed and engine load;Isothermal reference matching unit selects normal state reference curve;Displacement layer construction unit sets multiple displacement layers;Bidirectional equal displacement phase band extraction unit extracts a pair of crank angles in opening branch and closing branch;Phase shift separation unit distinguishes overall phase shift and curve width variation, and determines comprehensive phase deviation;Compensation command generation unit generates phase compensation angle, and execution control unit drives variable valve timing actuator.The present application is used for diesel engine valve timing compensation control.

Description

Technical Field

[0001] This invention relates to the field of diesel engine valve train technology, and more specifically, to a diesel engine rocker arm phase drift compensation system. Background Technology

[0002] The valve train of a diesel engine relies on the crankshaft, camshaft, rocker arms, valves, return springs, and hydraulic tappets to collaboratively complete the intake and exhaust processes. Electronically controlled diesel engines typically manage valve timing through a crankshaft position sensor, engine control unit, and variable valve timing actuator. In models with hydraulic tappets, hydraulic circuit adjustments are also used to compensate for rocker arm displacement or clearance variations. Valve timing and rocker arm displacement affect intake and exhaust volume, combustion stability, emissions, and valve safety margin.

[0003] In on-site diagnostics, a common practice is to determine the valve timing based on the crankshaft angles corresponding to the opening and closing thresholds, and then compare this with the calibrated angles to generate a phase correction. This approach relies on a limited number of event points. When faced with thermal deformation, clearance changes, hydraulic tappet return delays, oil film changes, or signal noise, the opening and closing branches may not move in the same direction. Directly merging the deviations of the two angles can easily treat the curve width change as a whole phase shift, leading to repeated corrections or directional instability in the variable valve timing actuator.

[0004] Cylinder head temperature, engine speed, and engine load affect the baseline state of the rocker arm displacement curve. If the reference curve does not correspond to the current thermal state and load level, even if the valve timing is not abnormal, there may be an angle deviation reading. If only the maximum displacement or a single threshold point is used for judgment, it is difficult to distinguish the overall phase shift, the expansion or contraction of the open and closed branches, and the rocker arm displacement changes caused by the hydraulic tappet.

[0005] Therefore, when the on-board controller performs valve timing compensation using existing sensors and original actuators, it needs to perform comparative analysis of the rocker arm displacement curve within the crankshaft angular domain, and confirm the validity, synchronization reliability, and execution safety of the data before compensation. This ensures that the phase compensation angle and tappet compensation amount correspond to the actual operating state of the diesel engine's valve timing mechanism, reducing unnecessary actuator movements. Summary of the Invention

[0006] This invention provides a diesel engine rocker arm phase drift compensation system, which solves the technical problems mentioned in the background art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution.

[0008] A diesel engine rocker arm phase drift compensation system is applied to the valve train of a diesel engine, including a data acquisition unit, a isothermal reference matching unit, a displacement layer construction unit, a bidirectional iso-displacement phase band extraction unit, a phase translation separation unit, a compensation command generation unit, and an execution control unit; The data acquisition unit is used to acquire crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed, and engine load; The same temperature reference matching unit is used to select a normal state reference curve corresponding to the cylinder head temperature, the engine speed and the engine load. The normal state reference curve is a standard rocker arm displacement curve. The displacement layer construction unit is used to set multiple displacement layers between the minimum rocker arm displacement and the standard maximum displacement; The bidirectional equal displacement phase band extraction unit is used to extract the current open branch angle, current closed branch angle, standard open branch angle, and standard closed branch angle corresponding to the same displacement layer on the open branch and closed branch, and to form a standard bidirectional equal displacement phase band and the bidirectional equal displacement phase band of the current cycle. The phase translation separation unit is used to characterize the overall phase translation by the change of the current centerline angle relative to the standard centerline angle, to characterize the curve width change by the change of the current angle width relative to the standard angle width, and to determine the comprehensive phase deviation by the deviation corresponding to the overall phase translation. The compensation command generation unit is used to generate a phase compensation angle based on the comprehensive phase deviation; The execution control unit is used to send the phase compensation angle to the variable valve timing actuator.

[0009] Compared with the prior art, the present invention has the following substantial features and significant progress: This invention uses the crankshaft angle, rocker arm displacement, and cylinder head temperature of the diesel engine's valve train as field inputs. After matching with a temperature reference, it constructs multiple displacement layers and forms bidirectional equal displacement phase bands in the open and closed branches. This distinguishes between overall phase shift and curve width changes, reducing the probability of mistakenly treating the expansion or contraction of the open and closed branches as phase drift. Simultaneously, the system generates a phase compensation angle based on the comprehensive phase deviation and drives the variable valve timing actuator. It also generates a tappet compensation amount based on the maximum displacement difference and drives the controllable hydraulic tappet circuit. Combined with compensation permission judgment, closed-loop retesting, and safe valve timing calibration, this helps improve the responsiveness of valve timing compensation and the stability of diesel engine operation control. Attached Figure Description

[0010] Figure 1 This is the system architecture diagram of the present invention. Detailed Implementation

[0011] The following description is provided in conjunction with the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the invention; those skilled in the art can make equivalent substitutions or combinations for the specific implementations.

[0012] Example 1: This embodiment applies to the valve train of a diesel engine. The valve train includes components such as a crankshaft, camshaft, cam, rocker arm, valve, return spring, and hydraulic tappets. The crankshaft provides the angular reference for the valve train cycle. The camshaft drives the cam according to a fixed transmission relationship. The cam pushes the rocker arm, which in turn drives the valve to open and returns under the action of the return spring. This mechanical kinematic chain has clearly defined opening and closing branches within one working cycle. The opening branch corresponds to the segment where the rocker arm displacement increases with increasing crankshaft angle, and the closing branch corresponds to the segment where the rocker arm displacement decreases with increasing crankshaft angle. This embodiment involves a paired comparison of the rocker arm displacement curves under the same temperature, bidirectional, and equal displacement conditions.

[0013] Specifically, in actual diesel engine operation, cylinder head thermal deformation, rocker arm clearance changes, slower hydraulic tappet return, changes in oil film state, or a decrease in actual maximum displacement can all cause variations in the rocker arm displacement curve's width in the opening and closing branches. If the overall phase deviation is directly calculated based solely on the changes in the current opening and closing branch angles relative to the standard opening and closing branch angles, the curve width change may be mistakenly interpreted as an overall phase shift, leading to repeated corrections or unstable correction directions by the variable valve timing actuator. This implementation method processes the current opening and closing branch angles on the same displacement layer in pairs, ensuring that the overall phase shift is primarily reflected in the change of the current centerline angle relative to the standard centerline angle, and that the curve width change is primarily reflected in the change of the current angle width relative to the standard angle width. This improves the correspondence between the phase compensation angle and the actual movement state of the diesel engine's valve timing mechanism.

[0014] like Figure 1As shown, the system of this embodiment includes a data acquisition unit 100, a constant-temperature reference matching unit 200, a displacement layer construction unit 300, a bidirectional equal-displacement phase band extraction unit 400, a phase translation separation unit 500, a compensation command generation unit 600, and an execution control unit 700. The data acquisition unit 100 acquires crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed, and engine load, and sends the cylinder head temperature, engine speed, and engine load to the constant-temperature reference matching unit 200, and sends the crankshaft angle and rocker arm displacement to the bidirectional equal-displacement phase band extraction unit 400. The constant-temperature reference matching unit 200 selects a normal-state reference curve and sends it to the displacement layer construction unit 300. The displacement layer construction unit 300 sets multiple displacement layers between the minimum rocker arm displacement and the standard maximum displacement, and provides these multiple displacement layers to the bidirectional equal-displacement phase band extraction unit 400. The bidirectional equal-displacement phase band extraction unit 400 forms a standard bidirectional equal-displacement phase band and the current cycle's bidirectional equal-displacement phase band, and sends both to the phase translation separation unit 500. The phase shift separation unit 500 determines the comprehensive phase deviation and maximum displacement difference, and sends them to the compensation command generation unit 600. The compensation command generation unit 600 generates the phase compensation angle and tappet compensation amount. The execution control unit 700 sends the phase compensation angle to the variable valve timing actuator 800 and the tappet compensation amount to the controllable hydraulic tappet circuit 900. The variable valve timing actuator 800 and the controllable hydraulic tappet circuit 900 work together to act on the diesel engine valve train 1000. The operating status of the diesel engine valve train 1000 is then fed back to the data acquisition unit 100, forming a closed-loop control relationship.

[0015] Example 2: The data acquisition unit 100 is used to acquire crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed, and engine load. The crankshaft angle is calculated from the tooth pulses of the crankshaft position sensor and serves as the reference angle for the valve train cycle at each sampling point. The rocker arm displacement is measured by a laser micro-displacement sensor located in the valve cover and is used to generate the rocker arm displacement curve for the current cycle. The cylinder head temperature is measured by a cylinder head temperature sensor and is used to select the normal state reference curve corresponding to the current thermal state. Engine speed and engine load can be provided by the engine electronic control unit and are used to determine the operating condition index of the normal state reference curve and to judge compensation allowance. All of the above sensors and control signals are conventional hardware sources that can be used in the monitoring and control of the diesel engine's valve train.

[0016] Before the system is powered on or the diesel engine is started, the data acquisition unit 100 performs power supply checks, communication checks, and range checks on the crankshaft position sensor, laser micro-displacement sensor, and cylinder head temperature sensor. If the system also uses camshaft rotation angle or rocker arm vibration acceleration as auxiliary information, the data acquisition unit 100 also performs the same type of routine checks on the camshaft phase sensor and vibration acceleration sensor. After the checks are passed, the data acquisition unit 100 reads the initial distance between the laser micro-displacement sensor and the rocker arm measuring surface and uses this initial distance as the zero point of displacement for this operation; at the same time, it reads the crankshaft tooth missing position or the equivalent crankshaft reference position to establish the crankshaft rotation angle reference. If any data used for compensation has an open circuit, short circuit, signal out of bounds, or missing reference tooth, the data acquisition unit 100 sets the sensor data validity status to "compensation permission condition not met," and the execution control unit 700 does not output a new phase compensation angle.

[0017] This embodiment may also include a synchronous sampling unit. The synchronous sampling unit uses the tooth pulses output by the crankshaft position sensor as a unified sampling time base, adds the same crankshaft angle time marker to the rocker arm displacement and cylinder head temperature, aligning the rocker arm displacement and cylinder head temperature with the crankshaft angle, and establishes a data buffer according to the working cycle. The synchronous sampling unit can be implemented as an internal function of the data acquisition unit 100, or it can be implemented as an independent software unit that works in conjunction with the data acquisition unit 100.

[0018] When establishing a data buffer within each working cycle, the synchronous sampling unit stores the crankshaft angle sequence, rocker arm displacement sequence, cylinder head temperature record, and auxiliary validity markers corresponding to the same intake or exhaust rocker arm in the same data buffer. For four-stroke diesel engines, the synchronous sampling unit can distinguish between compression top dead center and exhaust top dead center by combining the camshaft angle, and divide the corresponding intake or exhaust rocker arm movement segment according to the cylinder firing order. This division is only used to ensure that the opening and closing branches of the current cycle correspond to the same actual mechanical motion process.

[0019] When engine speed changes rapidly, the synchronous sampling unit can employ angle-domain resampling to ensure that each working cycle has the same number of crankshaft angle sampling points. Angle-domain resampling can be achieved using adjacent-point linear interpolation; that is, given the known adjacent crankshaft angle sampling points and their corresponding rocker arm displacements, the corresponding rocker arm displacement is calculated based on the target crankshaft angle position. This process avoids deformation of the rocker arm displacement curve in the time domain solely due to time axis scaling, ensuring that subsequent displacement layer intersection point searches use the crankshaft angle as a unified reference.

[0020] The data acquisition unit 100 can determine a small number of isolated anomalies by using the continuity of adjacent points and the sensor range, and fill in the gaps through neighboring point interpolation. If a continuous anomaly reaches the continuous anomaly determination length, the data for this cycle is marked as invalid. The valid state of the sensor data is used both by the compensation permission judgment unit and the closed-loop retest and fault rollback unit. Since the phase band deviation calculation in this embodiment directly depends on the crankshaft angle, rocker arm displacement, and cylinder head temperature, if any of the above direct field inputs does not meet the valid state of the sensor data, the current cycle will not enter phase compensation.

[0021] The continuous anomaly detection length is determined by the continuous anomaly detection angle width and the crankshaft angle sampling interval. The continuous anomaly detection angle width can range from 1 degree to 3 degrees of crankshaft angle; in a specific embodiment, the continuous anomaly detection angle width is 2 degrees of crankshaft angle. The continuous anomaly detection length is determined by the following formula:

[0022] in, The length for continuous anomaly detection. To determine the angle width for continuous anomalies, The sampling interval is the crankshaft angle. If the rocker arm displacement, cylinder head temperature, crankshaft angle time marker, or auxiliary validity marker continuously reaches the continuous anomaly judgment length and does not meet the validity judgment, the data acquisition unit 100 sets the sensor data validity status to "not meeting the compensation permission condition".

[0023] Signal out-of-bounds conditions are jointly determined by the sensor's range boundaries and the controller's diagnostic boundaries. When the rocker arm displacement sampling value of the laser micro-displacement sensor is lower than the lower limit or higher than the upper limit of the rocker arm displacement sensor, it is determined to be a rocker arm displacement out-of-bounds condition; when the cylinder head temperature sampling value is lower than the lower limit or higher than the upper limit of the cylinder head temperature sensor, it is determined to be a cylinder head temperature out-of-bounds condition; when the crankshaft position sensor's tooth pulse interval exceeds 150% of the previous effective tooth pulse interval or is lower than 50% of the previous effective tooth pulse interval, it is determined to be a crankshaft position sensor tooth pulse abnormality. The above boundaries are all derived from the sensor manual, existing diagnostic boundaries of the diesel engine electronic control unit, or calibration records after maintenance.

[0024] Example 3: The same-temperature reference matching unit 200 is used to select a normal-state reference curve corresponding to cylinder head temperature, engine speed, and engine load. The normal-state reference curve is a standard rocker arm displacement curve, which reflects the relationship between rocker arm displacement and crankshaft angle under normal mechanical conditions. Since cylinder head temperature affects the thermal expansion state of components near the rocker arm, valves, and hydraulic tappets, and engine speed and engine load affect the operating state of the diesel engine valve train, the same-temperature reference matching unit 200 first determines the comparable operating condition range based on engine speed and engine load, and then determines the reference temperature or adjacent temperature calibration point based on cylinder head temperature.

[0025] In one implementation, the normal state reference curve is stored according to three indexes: reference temperature, engine speed, and engine load. After the data acquisition unit 100 sends the cylinder head temperature, engine speed, and engine load to the same-temperature reference matching unit 200, the same-temperature reference matching unit 200 first determines whether the engine speed and engine load are within the calibration range covered by the normal state reference curve. If the engine speed and engine load are not within the coverage range, the same-temperature reference matching unit 200 does not output a new normal state reference curve, and the compensation permission judgment unit does not allow compensation to proceed. If the engine speed and engine load are within the coverage range, the same-temperature reference matching unit 200 continues to determine the temperature matching difference based on the cylinder head temperature and the reference temperature.

[0026]

[0027] in, Due to poor temperature matching, For cylinder head temperature, The reference temperature is the temperature point corresponding to the normal state reference curve. The cylinder head temperature is acquired by the data acquisition unit 100. The temperature matching difference is used to determine whether a certain normal state reference curve can be directly used in the current cycle.

[0028]

[0029] in, This refers to the allowable temperature difference. The allowable temperature difference can be determined through routine calibration, such as recording the acceptable range of change in the normal rocker arm displacement curve when the cylinder head temperature changes on a test bench, and selecting a temperature difference that will not lead to misjudgment of valve timing. When the temperature matching difference does not exceed the allowable temperature difference, the same-temperature reference matching unit 200 selects the normal state reference curve corresponding to that reference temperature.

[0030] When the cylinder head temperature is between two temperature calibration points, the same-temperature reference matching unit 200 is used to obtain a normal-state reference curve through linear interpolation. Linear interpolation can be performed on a crankshaft angle-by-crankshaft reference curve corresponding to the lower temperature calibration point and the higher temperature calibration point under the same engine speed and engine load index. During interpolation, the crankshaft angle sampling points should be consistent; if the number of sampling points for the two temperature calibration points is different, they can be resampled in the angle domain to ensure they have the same crankshaft angle sampling points, and then linear interpolation can be performed on the rocker arm displacement at the same crankshaft angle position. This method belongs to conventional numerical processing based on known calibration points.

[0031] The output of the isothermal reference matching unit 200 is a normal state reference curve. This normal state reference curve serves as the basis for the displacement layer construction unit 300 to set multiple displacement layers, and also as the basis for the bidirectional iso-displacement phase band extraction unit 400 to extract the standard open branch angle and the standard closed branch angle. Since the normal state reference curve corresponds to the current cylinder head temperature, engine speed, and engine load, when comparing the current cycle's bidirectional iso-displacement phase band with the standard bidirectional iso-displacement phase band, the probability of misjudging normal thermal expansion or operating condition differences as an overall phase shift can be reduced.

[0032] Example 4: The displacement layer construction unit 300 is used to set multiple displacement layers between the minimum rocker arm displacement and the standard maximum displacement. The minimum rocker arm displacement is the lowest reference displacement used to set the displacement layers within a cycle, and the standard maximum displacement is the maximum displacement of the rocker arm under normal conditions in the current working condition. The displacement layer construction unit 300 sets multiple displacement layers according to the displacement range of the reference curve under normal conditions, and excludes the endpoints corresponding to the minimum rocker arm displacement and the standard maximum displacement from the multiple displacement layers. The reason for this setting is that there may be static noise near the minimum rocker arm displacement, and there may be peak-flat sections or local rebound near the standard maximum displacement. If the endpoints are used as displacement layers, the intersection points of the displacement layers are likely to be non-unique or affected by local noise.

[0033] The displacement layer building unit 300 can be configured with the j-th displacement layer as follows:

[0034] in, For the j-th displacement layer, For the minimum rocker arm displacement, For the number of displacement layers, This is the displacement layer number. This represents the standard maximum displacement. The number of displacement layers can be determined through routine calibration. Multiple displacement layers should cover the main effective stroke of the rocker arm. At the same time, it is important to avoid having too few displacement layers, which would cause an abnormality in a single displacement layer to have an excessive impact on the phase band deviation, and also to avoid having too many displacement layers, which would cause an unnecessary increase in the calculated load.

[0035] In the specific implementation, the minimum rocker arm displacement can be determined based on the stable position of the rocker arm before it begins effective movement in the normal state reference curve; the standard maximum displacement can be determined based on the maximum rocker arm displacement in the normal state reference curve. The displacement layer construction unit 300 does not use the actual maximum displacement of the current cycle to redefine multiple displacement layers, but instead uses the displacement range corresponding to the normal state reference curve. This ensures that the current cycle and the normal state reference curve are compared at the same displacement height.

[0036] Example 5: The bidirectional equal displacement phase band extraction unit 400 is used to extract the current open branch angle, current closed branch angle, standard open branch angle, and standard closed branch angle corresponding to the same displacement layer on the open and closed branches, forming a standard bidirectional equal displacement phase band and the bidirectional equal displacement phase band of the current cycle. The open branch is defined as the segment where the rocker arm displacement increases with the crankshaft angle, and the closed branch is defined as the segment where the rocker arm displacement decreases with the crankshaft angle. On the normal state reference curve, the open and closed branches are used to extract the standard open branch angle and standard closed branch angle; on the rocker arm displacement curve of the current cycle, the open and closed branches are used to extract the current open branch angle and current closed branch angle.

[0037] For each displacement layer, the bidirectional equal displacement phase band extraction unit 400 first finds the crankshaft angle when the rocker arm displacement reaches that displacement layer on the open branch of the normal state reference curve, obtaining the standard open branch angle; then it finds the crankshaft angle when the rocker arm displacement reaches the same displacement layer on the closed branch of the normal state reference curve, obtaining the standard closed branch angle. The standard open branch angle and the standard closed branch angle together constitute the two side boundaries of that displacement layer in the standard bidirectional equal displacement phase band. After all displacement layers are arranged according to the displacement layer number, the standard bidirectional equal displacement phase band is obtained.

[0038] The bidirectional equal-displacement phase band extraction unit 400 uses multiple displacement layers along the rocker arm displacement curve of the current cycle, and employs adjacent-point linear interpolation to obtain the rotation angle of the currently open branch and the rotation angle of the currently closed branch. Adjacent-point linear interpolation can be used when the displacement layer is located between the rocker arm displacements of adjacent sampling points, calculating the crankshaft angle corresponding to the intersection point based on the crankshaft angle and rocker arm displacement of the adjacent sampling points. Adjacent-point linear interpolation is only used to obtain the intersection point corresponding to the same displacement layer between discrete sampling points, and belongs to conventional numerical processing.

[0039] When a displacement layer cannot simultaneously obtain a unique currently open branch angle and a unique currently closed branch angle, the bidirectional equal displacement phase band extraction unit 400 excludes that displacement layer. Situations where a unique angle cannot be simultaneously obtained include situations where the actual maximum displacement is lower than that displacement layer, the rocker arm displacement signal is interrupted, local rebound causes multiple intersections in the same branch, and the sensor data validity status does not meet requirements. Excluded displacement layers do not participate in the single-layer centerline deviation statistical processing of the phase translation separation unit 500. If the number of unexcluded displacement layers is insufficient to cover the main effective stroke of the rocker arm, compensation is not entered in the current cycle.

[0040] Both the standard bidirectional equidisplacement phase band and the current cycle's bidirectional equidisplacement phase band are composed of paired rotation angles corresponding to multiple displacement layers. This set of rotation angles is passed to the phase translation separation unit 500 and used to calculate the current centerline rotation angle, the standard centerline rotation angle, the current angle width, and the standard angle width.

[0041] Example 6: The phase translation separation unit 500 is used to characterize the overall phase translation by the change in the current centerline angle relative to the standard centerline angle, to characterize the curve width change by the change in the current angle width relative to the standard angle width, and to determine the comprehensive phase deviation by the deviation corresponding to the overall phase translation. This unit receives the standard bidirectional equidisional phase band output by the bidirectional equidisional phase band extraction unit 400 and the bidirectional equidisional phase band of the current cycle, and calculates the centerline and angle width layer by layer for the displacement layers that have not been excluded.

[0042] For the j-th displacement layer, the phase translation separation unit 500 determines the current centerline angle and current angle width based on the current open branch angle and the current closed branch angle, and determines the standard centerline angle and standard angle width based on the standard open branch angle and the standard closed branch angle:

[0043] in, This is the current midline turning point. To open the side road corner, This is the current angle of the closed branch. The current centerline angle represents the common angular position of the open and closed branches on the same displacement layer in the current cycle.

[0044]

[0045] in, For standard centerline corners, To open the standard branch road corner, This is the standard closed branch angle. The standard centerline angle represents the common angular position on the same displacement layer in the normal state reference curve.

[0046]

[0047] in, Current angle width The branch road corner is currently closed. This represents the current open branch angle. The current angle width indicates the crankshaft angle range occupied by the rocker arm from the first time it passes through this displacement layer to the second time it passes through the same displacement layer in the current cycle.

[0048]

[0049] in, Standard angle width, To standard close the branch road corner, This is the standard open branch rotation angle. The standard angle width represents the crankshaft rotation angle range of the same displacement layer in the normal state reference curve.

[0050] When the diesel engine valve train undergoes a global phase shift, the current open branch angle and the current closed branch angle on the same displacement layer will change in the same direction. Therefore, the current centerline angle changes accordingly relative to the standard centerline angle, while the current angle width remains essentially unchanged relative to the standard angle width. Specifically, the co-directional change of the two angles can be represented by the common translation amount:

[0051] in, To open the branch road corner after the change, To close the branch corner after the change, To open the side road corner, The branch road corner is currently closed. This is the common translation amount.

[0052]

[0053] in, This is the angle of the changed centerline. To change the angle width, This is the current midline turning point. Current angle width This represents the common translation amount. Therefore, it can be seen that the overall phase translation is reflected through the change in the midline angle.

[0054] When open and closed branches expand or contract relative to each other, the rotation angles on both sides of the same displacement layer change in approximately opposite directions. Therefore, the current angle width changes accordingly relative to the standard angle width, while the common position of the current centerline rotation angle relative to the standard centerline rotation angle changes relatively little. Specifically, the inverse changes in the rotation angles on both sides can be represented by the amount of expansion on both sides:

[0055] in, To open the branch road corner after the change, To close the branch corner after the change, To open the side road corner, The branch road corner is currently closed. This refers to the amount of expansion on both sides.

[0056]

[0057] in, This is the angle of the changed centerline. To change the angle width, This is the current midline turning point. Current angle width This represents the expansion on both sides. Therefore, it can be seen that the change in curve width is reflected through the change in angle width.

[0058] The phase translation separation unit 500 determines the single-layer centerline deviation based on the change in the current centerline rotation angle relative to the standard centerline rotation angle, and determines the single-layer angle width change based on the change in the current angle width relative to the standard angle width.

[0059] in, For single-layer centerline deviation, This is the current midline turning point. This represents the standard centerline rotation angle. The single-layer centerline deviation is used to reflect the overall phase translation corresponding to the j-th displacement layer.

[0060]

[0061] in, For single-layer corner width variation, Current angle width This is the standard angle width. The variation in single-layer angle width is used to reflect the change in curve width corresponding to the j-th displacement layer.

[0062] The phase translation separation unit 500 performs statistical processing on the single-layer centerline deviations corresponding to the unexcluded displacement layers to reduce the impact of individual displacement layer anomalies, thereby obtaining the phase band deviation. The statistical processing includes taking the median of the single-layer centerline deviations corresponding to the unexcluded displacement layers:

[0063] in, For phase band deviation, This represents the centerline deviation of a single layer corresponding to the displacement layers that were not excluded. If there are excluded displacement layers, the median is only calculated for the centerline deviation of the single layer corresponding to the displacement layers that were not excluded.

[0064] The phase shift separation unit 500 also determines the centerline dispersion based on the degree of dispersion of the single-layer centerline deviation relative to the phase band deviation:

[0065] in, The midline discrete quantity, For single-layer centerline deviation, This represents the phase band deviation. The centerline dispersion is used to determine whether the single-layer centerline deviations obtained from multiple displacement layers are concentrated. If the centerline dispersion is too large, it indicates that the common positions between different displacement layers are inconsistent, and phase compensation should not be performed in the current loop.

[0066] When the centerline dispersion does not exceed the upper limit of the centerline dispersion and the amplitude of the single-layer angle width change does not exceed the allowable angle width difference, the phase translation separation unit 500 will take the phase band deviation as the comprehensive phase deviation:

[0067] in, To account for phase deviation, This represents the phase band deviation. The combined phase deviation is used to generate the phase compensation angle later.

[0068]

[0069] in, For the maximum displacement difference, For the standard maximum displacement, This represents the actual maximum displacement. The maximum displacement difference is used to generate the tappet compensation amount subsequently. The standard maximum displacement comes from the reference curve under normal conditions, while the actual maximum displacement comes from the rocker arm displacement curve of the current cycle.

[0070] Example 7: The compensation command generation unit 600 is used to generate a phase compensation angle based on the comprehensive phase deviation and to generate a tappet compensation amount based on the maximum displacement difference. After receiving the comprehensive phase deviation and maximum displacement difference output by the phase translation separation unit 500, the compensation command generation unit 600 first determines whether the compensation permission judgment unit allows entry into compensation. If the compensation permission judgment unit does not allow entry into compensation, the compensation command generation unit 600 retains the previous valid compensation command or outputs a zero-increment command. If entry into compensation is allowed, the compensation command generation unit 600 inverts the comprehensive phase deviation and multiplies it by the phase correction factor to obtain the phase compensation angle.

[0071]

[0072] in, For phase compensation angle, For phase correction magnification, To account for phase deviation, This is the lower limit of phase compensation. This is the upper limit of phase compensation. This indicates that the phase compensation angle is limited to between the lower and upper limits of phase compensation. The phase correction ratio, the lower and upper limits of phase compensation can all be determined by diesel engine bench calibration or the allowable range of the existing variable valve timing actuator.

[0073] The compensation command generation unit 600 also generates a tappet compensation amount based on the maximum displacement difference. The maximum displacement difference reflects the difference between the standard maximum displacement and the actual maximum displacement, and is applicable to adjusting the effective displacement of the hydraulic tappet end by driving the controllable hydraulic tappet circuit 900.

[0074]

[0075] in, For the compensation amount of the tappet, This is the displacement correction factor. For the maximum displacement difference, The rocker arm transmission ratio, As the lower limit of compensation for the support column, This is the upper limit of compensation for the support column. This indicates that the tappet compensation is limited to between the lower and upper limits of tappet compensation. The rocker arm transmission ratio is determined by the mechanical ratio between the displacement of the hydraulic tappet end and the displacement of the rocker arm measuring end. The displacement correction ratio, the lower and upper limits of tappet compensation can be calibrated by the allowable stroke and control sensitivity of the original controllable hydraulic tappet circuit.

[0076] The execution control unit 700 sends the phase compensation angle to the variable valve timing actuator 800. The variable valve timing actuator 800 can adjust the phaser oil circuit via a conventional solenoid valve, causing the camshaft to produce a limited advance or lag action relative to the crankshaft. The execution control unit 700 also sends the tappet compensation amount to the controllable hydraulic tappet oil circuit 900. The controllable hydraulic tappet oil circuit 900 can change the effective position of the hydraulic tappet plunger by adjusting the oil inlet or outlet timing, bringing the effective displacement of the rocker arm end back to the allowable range. When the execution control unit 700 outputs commands, it can use step-by-step small increments to avoid large-scale changes in valve timing or tappet position at once.

[0077] Example 8: This implementation also includes a compensation permission judgment unit and a closed-loop retest and fault rollback unit. The compensation permission judgment unit is used to allow compensation when the overall phase deviation reaches the deviation state that allows compensation but has not reached the safety state that prohibits compensation, and the sensor data validity state and synchronization state meet the compensation permission conditions. The deviation state that allows compensation can be determined by the overall phase deviation exceeding the allowable range of the overall phase deviation for several consecutive working cycles, so as to avoid unnecessary actions triggered by a single impact, single-point noise, or local rebound. The safety state that prohibits compensation may include situations such as the overall phase deviation exceeding the mechanical safety limit, the maximum displacement difference exceeding the compensable range of the hydraulic tappet, the amplitude of the single-layer angle width change exceeding the allowable angle width difference, the centerline dispersion exceeding the centerline dispersion limit, and unstable engine speed or engine load.

[0078] The valid sensor data status indicates whether crankshaft angle, rocker arm displacement, and cylinder head temperature can be used for calculation in this cycle. The synchronization status indicates whether the tooth pulses output by the crankshaft position sensor can be used as a unified sampling time base, and whether the rocker arm displacement and cylinder head temperature have been appended with the same crankshaft angle time stamp. If the valid sensor data status or synchronization status does not meet the compensation permission conditions, the compensation permission judgment unit does not allow compensation to proceed, and the execution control unit 700 maintains the original valve train calibration or the safety valve train calibration.

[0079] The closed-loop retest and fault rollback unit is used to reacquire the comprehensive phase deviation and maximum displacement difference after compensation, and to roll back to the safe valve calibration when the comprehensive phase deviation or maximum displacement difference does not converge, the sensor data validity status does not meet the compensation permission conditions, the synchronization status does not meet the compensation permission conditions, or the variable valve timing actuator 800 or the controllable hydraulic tappet circuit 900 malfunctions. During closed-loop retest, after the actuator reaches the target position and a normal stabilization time has elapsed, the system re-executes data acquisition, synchronous sampling, same-temperature reference matching, displacement layer construction, bidirectional iso-displacement phase band extraction, and phase translation separation to obtain a new comprehensive phase deviation and a new maximum displacement difference.

[0080] If the new overall phase deviation returns to the allowable range, and the new maximum displacement difference returns to the allowable range, the closed-loop retest and fault rollback unit maintains the current compensation value. If a residual deviation still exists, but the residual deviation has not reached the safe state where compensation is prohibited, the compensation command generation unit 600 can repeatedly correct in small increments within the lower limit of phase compensation, the upper limit of phase compensation, the lower limit of tappet compensation, and the upper limit of tappet compensation. If the overall phase deviation or the maximum displacement difference does not converge after continuous correction, or if the variable valve timing actuator 800 or the controllable hydraulic tappet circuit 900 reports a fault, the closed-loop retest and fault rollback unit stops further correction and rolls back to the safe valve timing calibration.

[0081] The safe valve timing calibration is a conservative valve timing state preset by the engine manufacturer or the diesel engine control system. It is used to ensure that the diesel engine valve train 1000 has sufficient mechanical safety margin when compensation conditions are not met. After reverting to the safe valve timing calibration, the data acquisition unit 100 can continue to record crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed, engine load, comprehensive phase deviation, maximum displacement difference, phase compensation angle, tappet compensation amount, sensor data validity status, and synchronization status, so that maintenance personnel can judge mechanical wear, thermal deformation, or hydraulic tappet abnormalities.

[0082] As an optional implementation, the diesel engine is at a stable engine speed and load, the cylinder head temperature is near a certain reference temperature, and both the valid state and synchronization state of the sensor data meet the compensation allowable conditions. The rocker arm displacement curve acquired by the data acquisition unit 100 is basically consistent with the normal state reference curve selected by the same temperature reference matching unit 200. The bidirectional equal displacement phase band formed by the bidirectional equal displacement phase band extraction unit 400 for the current cycle is close to the standard bidirectional equal displacement phase band, the change of the current centerline angle relative to the standard centerline angle is small, and the change of the current angle width relative to the standard angle width is also small. The comprehensive phase deviation obtained by the phase translation separation unit 500 is within the allowable range of comprehensive phase deviation, and the maximum displacement difference is also within the allowable range of maximum displacement difference. The compensation command generation unit 600 does not generate new effective phase compensation angles and tappet compensation amounts, and the execution control unit 700 maintains the current position of the actuator.

[0083] As an optional implementation, the rocker arm displacement curve in the diesel engine valve train 1000 is either entirely ahead or entirely behind the normal state reference curve, but there is no significant change in curve width between the open and closed branches. The current open branch angle and the current closed branch angle on multiple displacement layers move in the same direction, the current centerline angle shows a consistent change relative to the standard centerline angle, and the current angle width changes little relative to the standard angle width. The phase translation separation unit 500 takes the median of the single-layer centerline deviation corresponding to the displacement layers that have not been excluded to obtain the phase band deviation, and takes the phase band deviation as the comprehensive phase deviation when the centerline dispersion does not exceed the upper limit of the centerline dispersion and the amplitude of the single-layer angle width change does not exceed the allowable difference in angle width. The compensation command generation unit 600 generates a phase compensation angle accordingly, and the execution control unit 700 sends the phase compensation angle to the variable valve timing actuator 800 to adjust the valve timing in the direction of reducing the comprehensive phase deviation.

[0084] As an optional implementation, during diesel engine operation, cylinder head thermal deformation, rocker arm clearance changes, slowed hydraulic tappet return, or oil film state changes may occur, causing the opening and closing branches to expand or contract relative to each other. In such cases, using a single opening threshold point and a single closing threshold point could easily lead to the inverse changes in the opening and closing branch angles being mistakenly interpreted as an overall phase shift. In this embodiment, the bidirectional equal displacement phase band extraction unit 400 extracts the current opening and closing branch angles in pairs across multiple displacement layers, while the phase shift separation unit 500 calculates the change in the current angle width relative to the standard angle width. When the magnitude of the angle width change in a single layer exceeds the allowable angle width difference, the compensation permission judgment unit disallows using this cycle as the basis for phase compensation, thereby reducing the probability of miscompensation caused by curve width changes.

[0085] As an optional implementation, the actual maximum displacement of the current cycle is lower than the standard maximum displacement. The displacement layer construction unit 300 still sets multiple displacement layers according to the displacement range of the normal state reference curve itself, and the bidirectional equal displacement phase band extraction unit 400 uses multiple displacement layers to extract the current open branch angle and the current closed branch angle. If a higher displacement layer cannot simultaneously obtain a unique current open branch angle and a unique current closed branch angle due to insufficient actual maximum displacement, then the displacement layer is excluded; the displacement layers that are not excluded can still be used to calculate the comprehensive phase deviation. At the same time, the phase translation separation unit 500 determines the maximum displacement difference based on the difference between the standard maximum displacement and the actual maximum displacement, the compensation command generation unit 600 generates the tappet compensation amount based on the maximum displacement difference, and the execution control unit 700 sends the tappet compensation amount to the controllable hydraulic tappet circuit 900.

[0086] As an optional implementation, if the crankshaft position sensor loses pulses, the laser micro-displacement sensor exceeds its range, the cylinder head temperature sensor signal is interrupted, the synchronization state does not meet the compensation permission conditions, the variable valve timing actuator 800 feedback fault occurs, or the controllable hydraulic tappet circuit 900 feedback fault occurs, the compensation permission judgment unit will not allow compensation to proceed. The closed-loop retest and fault rollback unit will stop further correction and roll back to the safe valve timing calibration. The system can continue to record the crankshaft angle, rocker arm displacement, cylinder head temperature, overall phase deviation, maximum displacement difference, phase compensation angle, and tappet compensation amount before and after the fault, so that maintenance personnel can confirm whether there is mechanical wear, thermal deformation, or hydraulic tappet abnormality in the diesel engine valve timing mechanism 1000.

[0087] It should be noted that this implementation can be achieved by a diesel engine electronic control unit, a stand-alone industrial controller, or an embedded controller. The controller has at least a sensor input interface, a data buffer unit, a computing unit, and an execution output interface. The sensor input interface receives engine speed and engine load data from the crankshaft position sensor, laser micro-displacement sensor, cylinder head temperature sensor, and the engine electronic control unit; if further confirmation of valve train operation or abnormal vibration is required, it can also receive camshaft angle and rocker arm vibration acceleration. The execution output interface sends a phase compensation angle to the variable valve timing actuator 800 and a tappet compensation amount to the controllable hydraulic tappet circuit 900.

[0088] It should be noted that the normal state reference curve can be stored as an array of rocker arm displacements arranged by crankshaft angle, and indexed according to reference temperature, engine speed, and engine load. The number of displacement layers, allowable temperature difference, allowable angle width difference, upper limit of centerline dispersion, phase correction ratio, displacement correction ratio, rocker arm transmission ratio, lower limit of phase compensation, upper limit of phase compensation, lower limit of tappet compensation, and upper limit of tappet compensation can all be obtained through diesel engine bench testing, factory calibration, or calibration after maintenance.

[0089] It should be noted that, in order to ensure that the normal state reference curve output by the same temperature reference matching unit 200 can be directly reproduced, in one embodiment, the normal state reference curve is established during the stable operation phase of the diesel engine on the factory bench, after maintenance bench, or after complete engine maintenance. Before calibration, it is confirmed that the crankshaft, camshaft, cam, rocker arm, valve, return spring, hydraulic tappet, variable valve timing actuator 800, and controllable hydraulic tappet oil circuit 900 are all in the normal mechanical state specified in the maintenance manual. The laser micro-displacement sensor, crankshaft position sensor, cylinder head temperature sensor, engine speed signal, and engine load signal are all checked for power supply, communication, range, and zero point. During calibration, the variable valve timing actuator 800 is maintained at the reference phase position, the controllable hydraulic tappet oil circuit 900 is maintained at the reference tappet position, and the lubricating oil pressure is within the normal pressure range allowed by the diesel engine controller. The data acquisition unit 100 collects the crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed, and engine load, and the synchronous sampling unit writes them into the data buffer according to the same crankshaft angle time mark.

[0090] The normal-state reference curve establishes a three-dimensional operating condition index based on reference temperature, engine speed, and engine load. Each operating condition index point corresponds to a reference temperature, an engine speed calibration point, and an engine load calibration point. The setting of the operating condition index points follows the existing temperature, speed, and load calibration grid of the diesel engine electronic control unit, or adopts conventional steady-state operating condition points already covered in bench tests. For the same operating condition index point, after the cylinder head temperature enters the allowable temperature difference corresponding to the reference temperature, the engine speed enters the stable engine speed range, and the engine load enters the stable engine load range, the rocker arm displacement curve corresponding to the number of reference calibration cycles is continuously collected. The number of reference calibration cycles can be 10 to 30 working cycles; in a specific embodiment, the number of reference calibration cycles is 20 working cycles.

[0091] The synchronous sampling unit resamples the rocker arm displacement curve of each reference calibration cycle to the same reference crankshaft angle grid point. The reference crankshaft angle grid point is determined by the crankshaft angle sampling interval, which can be from 0.1 degrees to 1 degree crankshaft angle; in a specific embodiment, the crankshaft angle sampling interval is 0.5 degrees crankshaft angle. For the reference crankshaft angle grid point... , No. The rocker arm displacement of each reference calibration cycle is denoted as... The reference calibration cycle number is denoted as The normal state reference curve is based on It means that, among them For reference temperature, Engine speed, For engine load. The normal state reference curve can be determined by the median of the same reference crankshaft angle grid points:

[0092] After the normal state reference curve is formed, the displacement layer construction unit 300 determines the minimum rocker arm displacement and the standard maximum displacement from this normal state reference curve. The minimum rocker arm displacement is taken as the median of the normal state reference curve within the set of crankshaft angles in the stationary segment. The set of crankshaft angles in the stationary segment is the angle range in which the rocker arm has not yet entered the effective opening motion and the return spring keeps the rocker arm stationary. The standard maximum displacement is taken as the maximum value of the normal state reference curve within one working cycle.

[0093]

[0094] To ensure that the normal-state reference curve can serve as the standard rocker arm displacement curve, the calibration data screening process excludes reference calibration cycles where the sensor data validity status does not meet the requirements, reference calibration cycles with abnormal crankshaft angle tooth loss, reference calibration cycles where the rocker arm displacement exceeds the sensor range, reference calibration cycles where the rocker arm vibration acceleration shows impact or abnormal high-frequency vibration, and reference calibration cycles where the standard maximum displacement deviates significantly from the median value of the cycle within the same working condition index point. A normal-state reference curve is allowed to be generated if the number of remaining reference calibration cycles after screening is not less than 70% of the total number of reference calibration cycles; if it is less than this proportion, the calibration of the working condition index point must be re-executed.

[0095] The calibration qualification criteria for the normal state reference curve are as follows: the standard maximum displacement dispersion of the remaining reference calibration cycle within the same operating condition index point does not exceed three times the repeatability error of the laser micro-displacement sensor; the dispersion of the standard open branch angle and the standard closed branch angle does not exceed three times the crankshaft angle sampling interval; the open branch and the closed branch can form monotonically changing segments within the main effective stroke. If any calibration qualification criterion is not met, the operating condition index point will not be written into the normal state reference curve storage area. The normal state reference curve storage area is called by the isothermal reference matching unit 200 according to the reference temperature, engine speed, and engine load index, and outputs the normal state reference curve to the displacement layer construction unit 300. After the laser micro-displacement sensor is reinstalled, the rocker arm clearance is repaired, the hydraulic tappet is replaced, the variable valve timing actuator 800 is repaired, the controllable hydraulic tappet oil circuit 900 is repaired, or the diesel engine valve timing mechanism 1000 is overhauled, the normal state reference curve is re-established for the affected cylinder and the affected rocker arm.

[0096] It should be noted that the number of displacement layers is determined by the displacement layer construction unit 300 within the main effective stroke of the reference curve under normal conditions. The number of displacement layers should ensure that multiple displacement layers cover the intermediate section between the minimum rocker arm displacement and the standard maximum displacement, while avoiding noise in the stationary section and the flat peak section. The number of displacement layers can be 5 to 9; in a specific embodiment, the number of displacement layers is 7. The number of effective displacement layers used for statistics by the phase translation separation unit 500 in the current cycle should not be lower than the lower limit of the effective displacement layer number, which is determined according to the number of displacement layers:

[0097] in, This is the lower limit for the number of effective displacement layers. The number of displacement layers. If the number of displacement layers in the current cycle that can simultaneously obtain the unique currently open branch angle and the unique currently closed branch angle is lower than the lower limit of the effective displacement layer number, the bidirectional equal displacement phase band extraction unit 400 will mark the bidirectional equal displacement phase band of the current cycle as not meeting the phase translation separation condition, and the compensation permission judgment unit will not allow the compensation to proceed.

[0098] The allowable temperature difference is determined by the change in the normal-state reference curve caused by cylinder head temperature variations during bench calibration. Specifically, under the same engine speed and load, the cylinder head temperature is gradually varied around the reference temperature, and the normal-state reference curve, standard open branch angle, and standard closed branch angle are recorded at different cylinder head temperatures. When the change in the standard centerline angle caused by the temperature matching difference does not exceed three times the crankshaft angle sampling interval, and the change in the standard maximum displacement does not exceed three times the repeatability error of the laser micro-displacement sensor, this temperature matching difference can be used as a candidate value for the allowable temperature difference. In one specific embodiment, the allowable temperature difference is a calibration value within the range of 2 to 5 degrees Celsius.

[0099] The permissible angle width is determined by the degree of angle width dispersion of the normal calibration cycle under the same working condition index point. After calculating the standard angle width of the remaining reference calibration cycles within the same working condition index point at each displacement layer, the standard deviation of the angle width calibration is obtained. Allowable difference in angle width It can be determined by the larger constraint between the standard deviation of the angle width calibration and the crankshaft angle sampling interval:

[0100] in, For the allowable difference in angle width, Standard deviation is calibrated for angle width. The crankshaft angle sampling interval is used. The upper limit of centerline dispersion is determined by the dispersion of single-layer centerline deviation in the normal calibration cycle under the same operating condition index point. After calculating the single-layer centerline deviation of each reference calibration cycle relative to the normal state reference curve, the standard deviation of centerline deviation calibration is obtained. Upper limit of midline dispersion It can be determined by the larger constraint between the standard deviation of the centerline deviation calibration and the crankshaft angle sampling interval:

[0101] in, The upper limit of the midline dispersion. To calibrate the standard deviation of the midline deviation, The crankshaft angle sampling interval. The allowable difference in angle width and the upper limit of centerline dispersion are both crankshaft angle quantities, and have the same crankshaft angle dimensions as the current angle width, standard angle width, single-layer angle width variation, single-layer centerline deviation, and centerline dispersion.

[0102] The phase correction ratio is determined by the response characteristics calibration of the variable valve timing actuator 800, the displacement correction ratio is determined by the response characteristics calibration of the controllable hydraulic tappet circuit 900, and the rocker arm transmission ratio is determined by the mechanical transmission relationship between the rocker arm and valve in the diesel engine valve train 1000. Both the phase correction ratio and the displacement correction ratio are dimensionless calibration ratios, and the rocker arm transmission ratio is a dimensionless mechanical ratio. The phase correction ratio can be between 0.2 and 1.0, and the displacement correction ratio can also be between 0.2 and 1.0. Calibration starts with a smaller calibration ratio to gradually reduce the overall phase deviation and maximum displacement difference after closed-loop retesting without causing reverse over-limits. The rocker arm transmission ratio adopts the design transmission ratio of the diesel engine valve train 1000 or the test value given in the maintenance manual.

[0103] The lower and upper limits of phase compensation are jointly determined by the mechanical limit of the variable valve timing actuator 800, the allowable phase adjustment range of the controller, and the safe valve timing calibration of the diesel engine. The lower and upper limits of tappet compensation are jointly determined by the stroke limit of the controllable hydraulic tappet circuit 900, the hydraulic response range, and the allowable valve clearance compensation range of the diesel engine valve timing mechanism 1000. After the compensation command generation unit 600 generates the phase compensation angle, the execution control unit 700 limits the phase compensation angle between the lower and upper limits of phase compensation; after the compensation command generation unit 600 generates the tappet compensation amount, the execution control unit 700 limits the tappet compensation amount between the lower and upper limits of tappet compensation. If the limited phase compensation angle or the limited tappet compensation amount still cannot meet the safety conditions of the compensation permission judgment unit, the execution control unit 700 does not output a new execution command and maintains the safe valve timing calibration.

[0104] It should be noted that the bidirectional equal displacement phase band extraction unit 400 uses the same adjacent point linear interpolation rule on both the normal state reference curve and the current cycle rocker arm displacement curve. Let the adjacent crankshaft angle sampling points be... and The adjacent rocker arm displacement sampling values ​​are and The j-th displacement layer is When the j-th displacement layer is located between adjacent rocker arm displacement sampling values ​​and At that time, the crankshaft rotation angle at the intersection point corresponding to the j-th displacement layer Determine by the following formula:

[0105] The open and closed branches are divided by the reference crankshaft angle grid point where the maximum rocker arm displacement is located. The section before the maximum rocker arm displacement, where the overall rocker arm displacement increases with increasing crankshaft angle, is the open branch; the section after the maximum rocker arm displacement, where the overall rocker arm displacement decreases with increasing crankshaft angle, is the closed branch. If localized springback causes short, non-monotonic fluctuations, the bidirectional equal displacement phase band extraction unit 400 first determines whether the fluctuation belongs to an isolated anomaly based on the crankshaft angle sampling interval and sensor repeatability error. If it belongs to an isolated anomaly, it is filled in continuously by adjacent points; if it does not belong to an isolated anomaly, the displacement layer is marked as invalid on that branch.

[0106] The rule for determining the unique intersection point is as follows: Within an open branch, the j-th displacement layer is only allowed to fall within one adjacent sampling point interval, and a current open branch angle or a standard open branch angle is obtained by linear interpolation of adjacent points; within a closed branch, the j-th displacement layer is only allowed to fall within one adjacent sampling point interval, and a current closed branch angle or a standard closed branch angle is obtained by linear interpolation of adjacent points. If there are two or more adjacent sampling point intervals that meet the crossing condition in the same branch, the intersection point connected to the longest monotonic change segment of that branch is selected first; if there are still two or more intersection points that cannot be distinguished, the j-th displacement layer is marked as invalid in the current loop. Both are equal to the j-th displacement layer. Only when the adjacent intervals at both ends of the platform segment can jointly confirm a crossing, the crankshaft angle at the midpoint of the platform segment is taken as the crankshaft angle at the intersection point; otherwise, the j-th displacement layer is marked as invalid on the branch.

[0107] An effective displacement layer must simultaneously meet the following conditions: the j-th displacement layer has a unique standard open branch turning angle on the standard open branch, a unique standard closed branch turning angle on the standard closed branch, a unique currently open branch turning angle on the currently open branch, and a unique currently closed branch turning angle on the currently closed branch; and the j-th displacement layer does not fall into the static noise region or the peak-top flat region. Only then are the single-layer centerline deviation, single-layer angle width variation, current centerline turning angle, current angle width, standard centerline turning angle, and standard angle width of the effective displacement layer sent to the phase translation separation unit 500. Therefore, Figure 1 The data output by the bidirectional equidisional phase band extraction unit 400 to the phase translation separation unit 500 is not all unfiltered intersection points, but rather the standard bidirectional equidisional phase band and the bidirectional equidisional phase band of the current cycle after satisfying the unique intersection point rule.

[0108] It should be noted that after receiving the comprehensive phase deviation and maximum displacement difference output by the phase translation separation unit 500, the compensation permission judgment unit does not immediately allow the compensation command generation unit 600 to output an execution command. Instead, it first performs a continuity judgment and an operating status judgment. The continuity judgment uses the number of compensation confirmation cycles. The number of compensation confirmation cycles can be 3 to 5 working cycles; in a specific embodiment, the number of compensation confirmation cycles is 3 working cycles. Only when the comprehensive phase deviation exceeds the allowable range of comprehensive phase deviation and the number of effective displacement layers is not lower than the lower limit of the number of effective displacement layers within the working cycles corresponding to the number of continuous compensation confirmation cycles, does the compensation permission judgment unit consider the phase drift to be continuous.

[0109] The allowable range of the overall phase deviation is jointly determined by the upper limit of the centerline discreteness and the crankshaft angle sampling interval. The boundary value corresponding to the allowable range of the overall phase deviation is denoted as... Its value is determined by the following formula:

[0110] in, To determine the boundary values ​​corresponding to the allowable range of phase deviation, The upper limit of the midline dispersion. The sampling interval is the crankshaft angle. At that time, the overall phase deviation is within the allowable range of overall phase deviation; when the working cycles corresponding to the number of continuous compensation confirmation cycles all meet the requirements... At that time, the compensation permission judgment unit confirms that the comprehensive phase deviation has reached the deviation state that allows compensation.

[0111] The allowable range of maximum displacement difference is determined jointly by the standard deviation of the maximum displacement calibration and the sampling resolution of the rocker arm displacement. The boundary value corresponding to the allowable range of maximum displacement difference is denoted as... Its value is determined by the following formula:

[0112] in, These are the boundary values ​​corresponding to the allowable range of maximum displacement difference. The standard deviation is calibrated for the maximum displacement. This is the sampling resolution for the rocker arm displacement. When... When the maximum displacement difference is within the allowable range of the maximum displacement difference; when Furthermore, if the hydraulic tappet's compensation range is not reached, the compensation command generation unit 600 allows the generation of tappet compensation amount based on the maximum displacement difference.

[0113] The mechanical safety upper limit is jointly determined by the lower and upper limits of the phase compensation of the variable valve timing actuator 800 and the safe valve timing calibration of the diesel engine. The boundary value corresponding to the mechanical safety upper limit is denoted as... Its value is determined by the following formula:

[0114] in, This represents the boundary value corresponding to the upper limit of mechanical safety. This is the lower limit of phase compensation. This is the upper limit of phase compensation. This defines the permissible phase deviation boundaries for safe valve timing calibration of diesel engines. If... The compensation permission judgment unit confirms that the safe state of prohibiting compensation has been reached, and the execution control unit 700 does not output a new phase compensation angle and returns to the safe valve timing calibration.

[0115] The compensable range of a hydraulic tappet is determined by the lower limit of tappet compensation, the upper limit of tappet compensation, the mechanical safety stroke of the tappet, and the rocker arm transmission ratio. The boundary values ​​corresponding to the compensable range of the hydraulic tappet are denoted as... Its value is determined by the following formula:

[0116] in, These are the boundary values ​​corresponding to the compensable range of the hydraulic tappet. The rocker arm transmission ratio, As the lower limit of compensation for the support column, The maximum compensation for the support pillar. For the safe travel of the tappet machinery. If The compensation permission judgment unit confirms that the safety state of prohibiting compensation has been reached, and the execution control unit 700 does not output a new tappet compensation amount and returns to the safe valve timing calibration.

[0117] The operational status assessment includes engine speed stability assessment, engine load stability assessment, lubricating oil pressure validity assessment, sensor data validity assessment, and synchronization status assessment. Engine speed stability assessment can be performed by continuously compensating to confirm that the difference between the maximum and minimum engine speeds within a specified number of cycles does not exceed 2% of the current engine speed. Engine load stability assessment can be performed by continuously compensating to confirm that the difference between the maximum and minimum engine loads within a specified number of cycles does not exceed 5% of the current engine load. If the lubricating oil pressure is below the allowable range of the diesel engine electronic control unit, the crankshaft position sensor tooth pulse is lost, the synchronization relationship between the camshaft angle and crankshaft angle is abnormal, the laser micro-displacement sensor exceeds its limits, the cylinder head temperature signal exceeds its limits, or communication verification fails, the compensation permission assessment unit will set the compensation permission condition to "not met."

[0118] When the compensation permission judgment unit allows compensation to proceed, the compensation command generation unit 600 generates a phase compensation angle based on the comprehensive phase deviation and a tappet compensation amount based on the maximum displacement difference. The execution control unit 700 outputs the phase compensation angle to the variable valve timing actuator 800 and the tappet compensation amount to the controllable hydraulic tappet circuit 900, and records the number of corrections. After each correction, the operating status of the diesel engine valve timing mechanism 1000 is re-acquired by the data acquisition unit 100, and the bidirectional equal displacement phase band extraction unit 400 and the phase translation separation unit 500 recalculate the comprehensive phase deviation and the maximum displacement difference. The closed-loop retest and fault rollback unit uses this information to determine whether convergence has occurred.

[0119] The maximum number of consecutive corrections can be 3 to 5; in one specific embodiment, the maximum number of consecutive corrections is 3. The corrected overall phase deviation is denoted as , No. The maximum displacement difference after the correction is denoted as When two consecutive closed-loop retests satisfy the following relationship, the closed-loop retest and fault backoff unit considers the overall phase deviation to have converged:

[0120] When two consecutive closed-loop re-measurements satisfy the following relationship, the closed-loop re-measurement and fault back-off unit considers the maximum displacement difference to have converged:

[0121] If the overall phase deviation has returned to the allowable range, and the maximum displacement difference has returned to the allowable range, the closed-loop retest and fault rollback unit confirms the compensation is complete, and the execution control unit 700 maintains the current phase compensation angle and the current tappet compensation amount. If the overall phase deviation or the maximum displacement difference still fails to converge after the number of consecutive corrections reaches the upper limit, or if any closed-loop retest cycle shows that the sensor data validity status is not met, the synchronization status is not met, the lubricating oil pressure is not met, the variable valve timing actuator 800 feedback is abnormal, or the controllable hydraulic tappet circuit 900 feedback is abnormal, the closed-loop retest and fault rollback unit triggers fault rollback. During fault rollback, the execution control unit 700 stops outputting a new phase compensation angle and a new tappet compensation amount, sets the variable valve timing actuator 800 and the controllable hydraulic tappet circuit 900 to the safe valve timing calibration allowed by the diesel engine electronic control unit, and records the fault code for maintenance diagnosis.

[0122] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A diesel engine rocker arm phase drift compensation system, applied to the valve train of a diesel engine, characterized in that, It includes a data acquisition unit, a isothermal reference matching unit, a displacement layer construction unit, a bidirectional iso-displacement phase band extraction unit, a phase translation separation unit, a compensation command generation unit, and an execution control unit; The data acquisition unit is used to acquire crankshaft angle, rocker arm displacement, cylinder head temperature, engine speed and engine load; The same temperature reference matching unit is used to select a normal state reference curve corresponding to the cylinder head temperature, the engine speed and the engine load. The normal state reference curve is a standard rocker arm displacement curve. The displacement layer building unit is used to set multiple displacement layers between the minimum rocker arm displacement and the standard maximum displacement; The bidirectional equal displacement phase band extraction unit is used to extract the current open branch angle, current closed branch angle, standard open branch angle, and standard closed branch angle corresponding to the same displacement layer on the open branch and closed branch, and to form a standard bidirectional equal displacement phase band and the bidirectional equal displacement phase band of the current cycle. The phase translation separation unit is used to characterize the overall phase translation by the change of the current centerline angle relative to the standard centerline angle, to characterize the curve width change by the change of the current angle width relative to the standard angle width, and to determine the comprehensive phase deviation by the deviation corresponding to the overall phase translation. The compensation command generation unit is used to generate a phase compensation angle based on the comprehensive phase deviation; The execution control unit is used to send the phase compensation angle to the variable valve timing actuator.

2. The diesel engine rocker arm phase drift compensation system according to claim 1, characterized in that, The same-temperature reference matching unit is used to determine the temperature matching difference based on the cylinder head temperature and the reference temperature, and select the normal state reference curve when the temperature matching difference does not exceed the allowable temperature difference; when the cylinder head temperature is between two temperature calibration points, the same-temperature reference matching unit is used to obtain the normal state reference curve through linear interpolation.

3. The diesel engine rocker arm phase drift compensation system according to claim 1, characterized in that, It also includes a synchronous sampling unit, which uses the tooth pulse output by the crankshaft position sensor as a unified sampling time base to add the same crankshaft angle time mark to the rocker arm displacement and the cylinder head temperature, so that the rocker arm displacement and the cylinder head temperature are aligned with the crankshaft angle, and establishes a data buffer according to the working cycle.

4. The diesel engine rocker arm phase drift compensation system according to claim 1, characterized in that, The displacement layer construction unit is used to set up multiple displacement layers according to the displacement range of the normal state reference curve itself, and exclude the endpoint corresponding to the lowest rocker arm displacement and the endpoint corresponding to the standard maximum displacement from the multiple displacement layers.

5. A diesel engine rocker arm phase drift compensation system according to claim 1, characterized in that, The bidirectional equal displacement phase band extraction unit is used to define the segment where the rocker arm displacement increases with the increase of the crankshaft angle as the open branch, and the segment where the rocker arm displacement decreases with the increase of the crankshaft angle as the closed branch, and to find the crankshaft angle when the rocker arm displacement reaches the same displacement layer on the open branch and the closed branch respectively.

6. A diesel engine rocker arm phase drift compensation system according to claim 5, characterized in that, The bidirectional equal displacement phase band extraction unit is used to obtain the current open branch angle and the current closed branch angle by linear interpolation of adjacent points along the rocker arm displacement curve of the current cycle using the multiple displacement layers, and to exclude displacement layers that cannot simultaneously obtain a unique current open branch angle and a unique current closed branch angle.

7. A diesel engine rocker arm phase drift compensation system according to claim 6, characterized in that, The phase translation separation unit is used to determine the current centerline angle and the current angle width based on the current open branch angle and the current closed branch angle, to determine the standard centerline angle and the standard angle width based on the standard open branch angle and the standard closed branch angle, to determine the single-layer centerline deviation based on the change of the current centerline angle relative to the standard centerline angle, and to determine the single-layer angle width change based on the change of the current angle width relative to the standard angle width.

8. A diesel engine rocker arm phase drift compensation system according to claim 7, characterized in that, The phase translation separation unit is used to perform statistical processing on the single-layer centerline deviation corresponding to the displacement layer that has not been excluded to reduce the impact of the single displacement layer anomaly and obtain the phase band deviation. The centerline dispersion is determined according to the degree of dispersion of the single-layer centerline deviation relative to the phase band deviation. When the centerline dispersion does not exceed the upper limit of the centerline dispersion and the amplitude of the single-layer angle width change does not exceed the allowable difference of the angle width, the phase band deviation is taken as the comprehensive phase deviation.

9. A diesel engine rocker arm phase drift compensation system according to claim 8, characterized in that, The statistical processing includes taking the median of the centerline deviation of the single layer corresponding to the displacement layers that were not excluded.

10. A diesel engine rocker arm phase drift compensation system according to claim 1, characterized in that, It also includes a compensation permission judgment unit and a closed-loop retest and fault rollback unit; The compensation permission judgment unit is used to allow compensation when the overall phase deviation reaches the deviation state that allows compensation but does not reach the safety state that prohibits compensation, and the sensor data validity state and synchronization state meet the compensation permission conditions. The compensation command generation unit is further configured to generate a tappet compensation amount based on the maximum displacement difference, wherein the maximum displacement difference is determined by the difference between the standard maximum displacement and the actual maximum displacement; the execution control unit is further configured to send the tappet compensation amount to the controllable hydraulic tappet circuit. The closed-loop retest and fault rollback unit is used to reacquire the comprehensive phase deviation and the maximum displacement difference after compensation, and roll back to the safe valve calibration when the comprehensive phase deviation or the maximum displacement difference does not converge, the sensor data validity state does not meet the compensation permission condition, the synchronization state does not meet the compensation permission condition, or the variable valve timing actuator or the controllable hydraulic tappet circuit fails.

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