Controllable one-way electromagnetic clutch slip diagnosis method

Abstract

This application discloses a controllable one-way electromagnetic clutch slippage diagnosis method, relating to the field of vehicle transmission control, including: acquiring the vehicle's hybrid state, the speed difference between the clutch ends, engine speed, and vehicle speed; determining whether the vehicle is in parallel or pure electric mode based on the hybrid state; when in parallel mode, determining whether the clutch is in slippage condition based on the speed difference and duration; when in pure electric mode, comprehensively judging the combination of speed difference, engine speed, and vehicle speed, as well as the duration, to determine whether it is in slippage condition; after identifying slippage, accumulating the number of occurrences and storing it in non-volatile memory upon power-off; reading the accumulated number and comparing it with a threshold, limiting torque if the number is less than the threshold, and prohibiting parallel operation if the number is greater than or equal to the threshold. This invention achieves differentiated fault diagnosis and implements graded limitation protection based on the long-term wear state of the hardware to prevent mechanical damage.

Description

Technical Field

[0001] This invention relates to the field of vehicle transmission control technology, specifically to a method for diagnosing slippage of a controllable one-way electromagnetic clutch. Background Technology

[0002] In the coupling and decoupling process of multiple power sources, hybrid electric vehicles typically employ a controllable one-way electromagnetic clutch to mechanically connect and disconnect the engine and transmission system. The clutch's operating state directly affects the vehicle's power transmission efficiency and operational stability.

[0003] Existing clutch slippage diagnostic strategies typically rely solely on a single speed difference threshold for real-time judgment. However, hybrid systems operate in multiple modes. In parallel drive mode, the clutch needs to maintain closed transmission, while in pure electric drive mode, it needs to remain physically disengaged. The expected mechanical engagement of the clutch differs significantly between these two modes. Conventional methods fail to establish differentiated judgment conditions based on the vehicle's hybrid status, making the system susceptible to interference from sensor pulse sampling errors at extremely low speeds, or resulting in incomplete fault feature capture in specific drive modes. This leads to misjudgments and missed diagnoses of clutch slippage.

[0004] Meanwhile, most existing diagnostic solutions are limited to transient fault responses within the current driving cycle, i.e., directly triggering an alarm or cutting off power when clutch slippage is detected. This processing logic ignores the irreversible physical wear of the internal friction components of the clutch accumulated with each slippage cycle. Due to the lack of recording historical slippage data across driving cycles and long-term health assessments, the system cannot intervene in advance by limiting torque when the clutch shows slight wear, causing the damaged clutch to continue to bear full-load torque in subsequent operation, which can easily lead to serious mechanical damage to the transmission system. In addition, directly cutting off the vehicle's power source after identifying a fault can cause the vehicle to unexpectedly stall during driving, failing to address both underlying hardware protection and the vehicle's degraded safe driving requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a controllable one-way electromagnetic clutch slippage diagnosis method, which solves the problems in the prior art that the lack of differentiated diagnostic standards for different hybrid drive modes leads to misjudgment and omission of clutch slippage, as well as the lack of tracking and recording of the long-term wear state of the clutch and graded protection, which can easily cause mechanical damage to the transmission system or unexpected loss of vehicle power.

[0006] To achieve the above objectives, the present invention provides a method for diagnosing slippage of a controllable one-way electromagnetic clutch, comprising the following steps:

[0007] Acquire vehicle operating status parameters, including the vehicle hybrid status, speed difference between the two ends of the clutch, engine speed, and vehicle speed.

[0008] The vehicle is determined to be in parallel or pure electric mode based on the overall vehicle hybrid status.

[0009] When the vehicle is in the parallel state, the controllable one-way electromagnetic clutch is determined to be in a slipping condition based on the speed difference between the two ends of the clutch and the duration of the speed difference between the two ends of the clutch exceeding the limit.

[0010] When the vehicle is in the pure electric state, the controllable one-way electromagnetic clutch is determined to be in the slipping condition by comprehensively judging the combination of the speed difference between the two ends of the clutch, the engine speed and the vehicle speed, as well as the duration of the combination of the states.

[0011] After the slipping condition is identified, the number of slipping conditions is accumulated, and the number of slipping conditions is stored in non-volatile memory when the power is off.

[0012] The number of slip-on conditions is read and compared with a preset slip-on life decay threshold. When the number of slip-on conditions is less than the slip-on life decay threshold, the parallel state is allowed and the transmission input torque is limited. When the number of slip-on conditions is greater than or equal to the slip-on life decay threshold, the parallel state is prohibited and a transmission system fault is reported.

[0013] This invention addresses the mechanical engagement characteristics of a controllable one-way electromagnetic clutch under different driving modes. It executes corresponding slippage diagnostic logic based on the hybrid status of the vehicle. After confirming slippage conditions, it records and stores the number of slippage conditions and limits the transmission input torque in stages based on the number of slippage conditions, thereby protecting the clutch hardware.

[0014] As a further improvement of the present invention, obtaining the speed difference between the two ends of the clutch includes: obtaining the speed of the clutch driving end and the speed of the clutch driven end, and taking the absolute value of the difference between the speed of the clutch driving end and the speed of the clutch driven end as the speed difference between the two ends of the clutch.

[0015] As a further improvement of the present invention, when the vehicle is in the parallel operation state, determining whether the controllable one-way electromagnetic clutch is in the slipping condition includes: determining whether the speed difference between the two ends of the clutch is greater than a set speed difference threshold, and whether the duration of satisfying this condition reaches a set first duration threshold; if so, confirming that the controllable one-way electromagnetic clutch has entered the slipping condition, controlling the energizing current output to the controllable one-way electromagnetic clutch actuator coil to zero, and transmitting an unexpected separation status message to the vehicle control unit. In the parallel operation state, the clutch is expected to be in a closed transmission state. The determination of whether the clutch has experienced unexpected relative slippage is based on the speed difference and time conditions, and the electromagnetic circuit is cut off upon confirmation.

[0016] As a further improvement of the present invention, when the vehicle is in the pure electric state, determining whether the controllable one-way electromagnetic clutch is in the slippery condition includes: determining whether the speed difference between the two ends of the clutch is less than a set pure electric speed difference threshold or whether the engine speed is greater than a set engine speed threshold, and the current vehicle speed is greater than a set vehicle speed threshold; if so, and the duration of satisfying the above determination conditions reaches a set second duration threshold, confirming that the controllable one-way electromagnetic clutch has entered the slippery condition, and synchronously shutting off the high-end power supply circuit and low-end control circuit of the controllable one-way electromagnetic clutch actuator coil to block the engine start request. In the pure electric state, the clutch is expected to be in the disengaged state. For the condition where the clutch cannot disengage or drags to engage, the speed difference, engine speed, and vehicle speed are comprehensively considered for determination, and the sampling interference in the low-speed range is eliminated using the vehicle speed condition.

[0017] As a further improvement of the present invention, the accumulation of the number of slip-fisted conditions includes: after confirming that the controllable one-way electromagnetic clutch has entered the slip-fisted condition and completing the numerical accumulation operation of the number of slip-fisted conditions, locking the corresponding fault status flag bit to stop repeated accumulation; when the controllable one-way electromagnetic clutch actuator coil completes a de-energization disengagement action and receives a closing energization command again, or when the current vehicle driving cycle ends and power is de-energized, the locked fault status flag bit is released. This mechanism is used to prevent repeated counting during a single slip-fisted condition.

[0018] As a further improvement of the present invention, the accumulation of the number of sliding friction conditions further includes: before performing the numerical accumulation operation, extracting the current count value of the number of sliding friction conditions and comparing it with the set maximum physical storage limit of the variable; if the maximum physical storage limit of the variable is reached, clamping the count value to the maximum physical storage limit of the variable.

[0019] As a further improvement of the present invention, storing the number of slippage conditions into the non-volatile memory when power is off includes: during the delayed power-off operation phase before the main power relay of the vehicle is disconnected, transferring the number of slippage conditions temporarily stored in the random access memory and writing it into the non-volatile memory built into the power domain controller.

[0020] As a further improvement of the present invention, when the number of slip-fusing conditions is less than the slip-fusing life decay threshold, the parallel state is allowed and the transmission input torque is limited, including: when the number of slip-fusing conditions is zero, no limit is imposed on the transmission input torque; when the number of slip-fusing conditions is greater than zero and less than the slip-fusing life decay threshold, an upper limit constraint is imposed on the transmission input torque transmitted to the transmission input end according to a preset derating coefficient, so as to reduce the force load on the worn clutch in the transmission.

[0021] As a further improvement of the present invention, when the controllable one-way electromagnetic clutch is confirmed to be in the slippage condition, if the vehicle is in the parallel state, a level one fault of the transmission system is reported; if the vehicle is in the pure electric state, a level three fault of the transmission system is reported; when the number of slippage conditions is greater than or equal to the slippage life decay threshold, the reported transmission system fault is specifically a level two fault of the transmission system, and the vehicle is forced to lock into operation in the pure electric state. By distinguishing different fault scenarios, the corresponding system fault level is output.

[0022] As a further improvement of the present invention, determining whether the vehicle is in a parallel state or a pure electric state based on the vehicle hybrid state includes: reading the state identifier bit variable representing the vehicle's target driving mode broadcast by the vehicle control unit, and identifying the current parallel state or the pure electric state of the vehicle by comparing the state identifier bit variable.

[0023] The above solution achieves the following beneficial technical effects:

[0024] This invention, by acquiring the hybrid status of the vehicle, divides clutch slippage diagnosis into two independent branches: parallel operation and pure electric operation. In parallel operation, it monitors abnormal clutch slippage and disengagement; in pure electric operation, it monitors clutch drag and engagement in conjunction with vehicle speed conditions. This diagnostic mechanism, which matches differentiated judgment conditions based on different operating modes, eliminates sampling interference in extremely low-speed ranges, avoids false alarms or missed alarms caused by using a single judgment standard, and improves the accuracy of clutch slippage fault identification.

[0025] This invention establishes a long-term recording and anti-repeated counting mechanism for clutch slippage counts. After confirming the slippage condition and completing a single accumulation, the fault status flag is locked, filtering out high-frequency abnormal counts caused by speed fluctuations. Furthermore, when the vehicle is powered off, the accumulated count is transferred to a non-volatile memory for permanent storage, achieving continuous tracking of the clutch's physical wear state and solving the problem that existing solutions rely solely on transient judgments and cannot accurately assess the overall hardware wear of the clutch.

[0026] This invention provides a graded operation protection strategy based on the number of slip-fusing cycles. The system compares the number of slip-fusing cycles with a lifespan decay threshold. When the clutch experiences initial wear, it limits the transmission input torque to reduce stress and delay hardware aging. When the number of slip-fusing cycles reaches the decay threshold, it actively disables parallel operation and forces the vehicle to operate in pure electric mode. This control method avoids severe mechanical damage to the transmission system while preserving the vehicle's degraded driving capability, preventing safety hazards caused by completely cutting off power during driving. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the system control architecture according to an embodiment of the present invention;

[0028] Figure 2 This is a flowchart illustrating the overall process of the controllable one-way electromagnetic clutch slippage diagnosis method according to an embodiment of the present invention.

[0029] Figure 3 This is a flowchart of the parallel state friction diagnosis branch of an embodiment of the present invention;

[0030] Figure 4 This is a flowchart of the pure electric state friction diagnosis branch of an embodiment of the present invention;

[0031] Figure 5 This is a flowchart of historical friction condition assessment and graded protection according to an embodiment of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0033] See attached document Figure 1 This invention provides a controllable one-way electromagnetic clutch slippage diagnosis method, which is implemented based on the powertrain architecture of a hybrid vehicle. In this embodiment, the hybrid system adopts a plug-in hybrid system architecture including a P1 motor and a P3 motor.

[0034] The system architecture at the hardware control level includes an engine control unit, a vehicle control unit, a motor control unit, and a clutch control unit. The slippage diagnostic method provided by this invention relies on the clutch control unit for logical operations and control command issuance. The vehicle control unit is configured as a controller with independent hardware.

[0035] The engine control unit, motor control unit, and clutch control unit are integrated within the power domain controller. The clutch control unit communicates with the vehicle control unit via a controller area network. The clutch control unit, motor control unit, and engine control unit rely on the runtime environment layer within the power domain controller to complete low-level signal interaction.

[0036] See attached document Figure 2 This invention provides a method for diagnosing slippage of a controllable one-way electromagnetic clutch, comprising the following steps:

[0037] S10, acquire vehicle operating status parameters, including vehicle hybrid status, speed difference between the two ends of the clutch, engine speed and vehicle speed.

[0038] S20 determines whether the vehicle is in parallel or pure electric mode based on the hybrid status of the vehicle and guides the control flow into the corresponding friction diagnostic branch.

[0039] S30: When the vehicle is in parallel operation, it determines whether the clutch is in a slipping condition based on the speed difference between the two ends of the clutch and its duration. If it is determined to be in a slipping condition, it reports a first-level fault of the transmission system to the system, reduces the clutch current to zero, and transmits the status command to the vehicle control unit at the same time.

[0040] S40: When the vehicle is in pure electric mode, it comprehensively judges the combination and duration of the speed difference between the two ends of the clutch, the engine speed and the vehicle speed to determine whether the clutch is in a slipping condition. If it is determined to be in a slipping condition, it reports a level 3 fault of the transmission system to the system, performs a shutdown operation on the high-end power supply and low-end control of the clutch, and prohibits the vehicle from switching to parallel operation mode in the current driving cycle.

[0041] S50, after identifying a slipping condition in any hybrid state, accumulates the number of slipping conditions that occur in the clutch and stores the number of slipping conditions in the non-volatile memory of the power domain controller when the vehicle is powered off.

[0042] S60 reads the number of slip condition cycles during vehicle power-on and operation, compares them with a preset threshold, and allows the current driving cycle to enter parallel operation mode and limits the transmission input torque when the number of slip condition cycles is less than the threshold. When the number of slip condition cycles is greater than the threshold, the parallel function is prohibited and the corresponding level of transmission system fault is reported to the system.

[0043] The specific implementation process of step S10 can be described in detail through multiple subsystem data interaction steps. The purpose of acquiring vehicle operating status parameters is to provide real-time data input for subsequent slippage fault diagnosis logic. As a preferred approach, to reduce the hardware cost of the control system, the operating status parameters required for this step are usually extracted through the communication network of the existing vehicle control unit or power domain controller, without adding additional physical sensors. The specific implementation process includes the following steps:

[0044] Step S110: Obtain vehicle hybrid state parameters. These parameters characterize the energy flow and target driving mode of the current vehicle powertrain. The clutch control unit reads the mode command messages processed by the vehicle control unit in real time through the runtime environment layer within the power domain controller. In this embodiment, the vehicle hybrid state mainly encompasses parallel operation and pure electric operation. Parallel operation refers to the vehicle's engine and drive motor being coupled in the mechanical transmission link, both jointly or alternately outputting power torque to the vehicle's drive wheels. Pure electric operation refers to the vehicle engine being shut down, fuel cut off, or idling and not participating in vehicle driving; the vehicle's driving power is mainly supplied by the power battery and provided via the drive motor. For the specific control algorithm used by the vehicle control unit to determine the vehicle hybrid state, those skilled in the art can refer to existing plug-in hybrid energy management strategies, which are well-known technologies in the field and will not be elaborated upon here.

[0045] Step S120: Obtain the speed difference parameters at both ends of the clutch and the engine speed parameters. The essence of clutch slippage is that the clutch slips relative to each other when it should be engaged, or engages with drag when it should be disengaged. Therefore, by monitoring the speed difference between the driving and driven ends, the physical engagement state of the clutch can be reflected intuitively and accurately. Based on this physical principle, the speed difference at both ends of the clutch is the core physical quantity for determining whether internal slippage occurs in a controllable one-way electromagnetic clutch.

[0046] In a plug-in hybrid architecture, the driving end of a controllable one-way electromagnetic clutch is mechanically connected to the engine output shaft, while its driven end is mechanically connected to the transmission input shaft. The clutch control unit acquires the shared speeds of the clutch driving and driven ends within the power domain system in real time. In practical applications, the clutch driving end speed is typically equivalent to the engine speed connected to it, and the clutch driven end speed is equivalent to the transmission input shaft speed. The speed difference between the two clutch ends is calculated using the absolute value of the difference between the clutch driving end speed and the clutch driven end speed. The expression corresponding to this calculation logic is as follows:

[0047] ;

[0048] In the formula, Indicates the speed difference between the two ends of the clutch; Indicates the speed at the driving end of the clutch; This indicates the speed of the clutch driven end. The clutch driving end speed and engine speed parameters mentioned above can be obtained from existing engine crankshaft position sensors or P1 motor rotary transformers; the clutch driven end speed parameter is obtained from an input shaft speed sensor located in the transmission. This complete sensor arrangement ensures independent, high-precision monitoring of the driving and driven ends under conditions of physical disengagement of the transmission chain. The engine speed parameter is used to assist in confirming whether the engine is being unexpectedly dragged in reverse under specific pure electric conditions, thereby indirectly verifying the clutch engagement status.

[0049] Step S130: Obtain vehicle speed parameters. Vehicle speed is primarily used to assess the vehicle's current overall motion state to set a reasonable blind zone for slippage diagnosis. Because sensor sampling accuracy is easily affected by pulse resolution fluctuations during extremely low-speed starts or stops, leading to speed calculation errors, a vehicle speed signal needs to be introduced for filtering. The clutch control unit receives the vehicle speed signal broadcast by the chassis anti-lock braking system or electronic stability program system. This signal is calculated based on the pulse signals collected by wheel speed sensors distributed across the four wheels. In practice, the vehicle speed threshold used to determine slippage conditions is typically set at around 10 km / h to effectively avoid signal noise interference in the low-speed range and ensure the reliability of the diagnostic results.

[0050] After acquiring the vehicle's operating status parameters, the system needs to select a matching diagnostic strategy based on the vehicle's actual operating conditions. The specific implementation process of step S20 can be explained in detail through the following steps:

[0051] Step S210: Analyze the hybrid status signal and identify the driving mode. After obtaining the vehicle hybrid status parameters, the clutch control unit parses the received underlying communication messages. In this embodiment, the vehicle control unit performs global energy management calculations based on parameters such as driver torque demand and power battery status, and broadcasts a status flag variable representing the vehicle's current target driving mode to the communication network. As a preferred approach, this status flag includes the aforementioned parallel and pure electric state commands. The clutch control unit continuously reads and compares this status flag to identify the specific operating mode of the vehicle.

[0052] Step S220: Diagnostic branch selection is performed based on the pattern recognition results. After clarifying the current hybrid status of the vehicle, the control system executes directional branching of the diagnostic program based on the status recognition results. In the hybrid powertrain system, the controllable unidirectional electromagnetic clutch has different expected mechanical engagement under different operating modes. Using a single judgment criterion can easily lead to false alarms or missed alarms; therefore, differentiated fault judgment logic needs to be matched according to the actual set operating conditions.

[0053] When the system detects that the vehicle is in parallel operation, it determines that the engine needs to participate in the vehicle's drive. From a mechanical transmission perspective, the controllable one-way electromagnetic clutch needs to transmit the power torque output from the engine to the transmission input, and its physical structure is expected to be in a stable closed transmission state. Based on this, the main program of the control system's guiding logic switches to the parallel operation slippage diagnosis branch. The core logic of this branch is to monitor whether the clutch has experienced unexpected disengagement, i.e., slippage under force in the traditional sense.

[0054] When the system detects that the vehicle is in a pure electric state, it determines that the vehicle is entirely driven by the drive motor. At this time, the engine stops outputting driving force, and the controllable one-way electromagnetic clutch is expected to be physically disengaged to prevent the drive motor's power from dragging the engine rotor in the reverse direction through the transmission chain, thus avoiding unnecessary energy loss or internal structural interference. Therefore, the control system directs the main logic program to the pure electric state slippage diagnosis branch. This branch is mainly used to identify whether the clutch is unable to disengage or exhibits abnormal dragging engagement. Abnormal engagement under such conditions also falls under the broad category of clutch slippage faults.

[0055] By constructing the aforementioned diversion mechanism based on the hybrid status of the vehicle, the clutch control unit can call the corresponding parameter monitoring combination and threshold judgment conditions for specific working scenarios of the vehicle, providing a decision-making basis for subsequent execution of targeted fault response measures.

[0056] See attached document Figure 3 After the control system determines that the vehicles are in a parallel operation state, the diagnostic logic enters the corresponding monitoring branch. The specific implementation process of step S30 includes the following steps:

[0057] Step S310 involves determining the slippage state based on both speed difference and time conditions. In parallel drive mode, the controllable one-way electromagnetic clutch, as a key node for transmitting engine torque, should maintain a closed transmission state without relative slippage. The system continuously monitors the speed difference between the two ends of the clutch; if abnormal slippage occurs in the transmission path, this speed difference parameter will change abruptly. To avoid system misjudgments caused by transient torsional vibrations in the transmission system or sensor signal disturbances, a time-dimensional anti-shake mechanism is introduced into the diagnostic algorithm.

[0058] Specifically, when the speed difference between the two ends of the clutch exceeds a set speed difference threshold, and the duration of this over-limit state reaches a set first duration threshold, the control system officially confirms that the clutch has entered a slip-friction condition. As a preferred approach, the speed difference threshold is set to 100 rpm, and the first duration threshold is set to 1 second. These two thresholds are set to ensure the system's responsiveness to actual slip-friction conditions while filtering transient impacts from the road surface. The judgment condition expression for the above logic is as follows:

[0059] ;

[0060] In the formula, Indicates the speed difference between the two ends of the clutch; This indicates the set speed difference threshold; Indicates the duration of the speed difference exceeding the limit; This indicates the set first duration threshold; Represents logical AND operations.

[0061] Step S320: Report the corresponding level of transmission system fault. After confirming that the clutch is slipping, the clutch control unit reports a level-one transmission system fault to the system via the vehicle communication network. In the technical solution of this invention, the response strategy for this system fault needs to be specifically defined. A level-one transmission system fault is defined as follows: the system allows the vehicle to maintain its driving state, the parallel drive function in the current driving cycle is not permanently disabled (i.e., the system allows an attempt to re-enter parallel mode after the fault condition is eliminated), and the vehicle issues a warning message to the driver, prompting them to contact after-sales service. This fault response level can avoid unexpected vehicle stalling due to directly cutting off the vehicle's power source when occasional slippage in parallel mode is detected, thus ensuring the vehicle's basic driving function under specific conditions.

[0062] Step S330: Execute the physical protection and status interaction actions for unexpected clutch disengagement. Simultaneously with triggering a system-level fault report, the clutch control unit intervenes in the hardware at the lower-level control circuit. In a specific implementation, the clutch control unit controls the energizing current output to the controllable one-way electromagnetic clutch actuator coil to zero. This operation is an emergency self-protection mechanism against the current transient slippage. Since controllable one-way electromagnetic clutches typically operate on a principle of energization and disengagement, when the control current of the actuator coil drops to zero, the electromagnetic attraction inside the clutch disappears. Under the action of the mechanical return spring or a similar return mechanism, the clutch disengages from the semi-engaged slippage state and enters the disengaged state. By cutting off the electromagnetic circuit to actively disengage the clutch, the risk of thermal ablation of the friction elements due to continuous relative sliding is reduced.

[0063] Simultaneously, the clutch control unit transmits the unexpected disengagement status message to the vehicle control unit. Upon receiving this status parameter, the vehicle control unit re-coordinates the target torque between the engine and the drive motor to reduce transmission torque fluctuations caused by forced clutch disengagement. For the specific algorithm of torque compensation, those skilled in the art can refer to existing hybrid vehicle torque smoothing control technology, which is well-known in the field and will not be elaborated upon here.

[0064] See attached document Figure 4When the vehicle control unit determines that the vehicle is in a pure electric state, the control logic will enter a dedicated slip-and-fist diagnostic branch for pure electric conditions. The specific implementation process of step S40 includes the following steps:

[0065] Step S410: Perform a pure electric slippage fault determination based on multiple combined states. In pure electric mode, the vehicle's driving power mainly relies on the output of the drive motor, and the engine is in a stopped or idling state. At this time, the controllable one-way electromagnetic clutch is expected to be in a fully disengaged physical state to cut off the reverse drag path of the transmission system to the engine. If the clutch experiences internal drag or fails to disengage due to an abnormality in the actuator, the rotational power at the transmission input end will be transmitted in reverse to the engine main shaft.

[0066] To detect this anomaly, the system comprehensively monitors the speed difference between the two ends of the clutch, engine speed, and vehicle speed. When the speed difference between the two ends of the clutch is too small, or the engine speed exceeds a set threshold, it indicates that an unexpected mechanical coupling has occurred between the driving and driven ends of the clutch. To eliminate misjudgment interference caused by the overall speed approaching zero when the vehicle is stationary or operating at extremely low speeds, the system introduces a limiting condition in the vehicle speed dimension.

[0067] As a preferred approach, when the speed difference between the two ends of the clutch is less than a set pure electric speed difference threshold, or the engine speed is greater than a set engine speed threshold, and the current vehicle speed is greater than a set vehicle speed threshold, if the duration of this combined state reaches a set second duration threshold, the system determines that the clutch has a failure to disengage. This fault is also classified as a slip condition of the controllable one-way electromagnetic clutch. Considering the sampling accuracy of conventional sensors, in this embodiment, the pure electric speed difference threshold is set to 100 rpm, the engine speed threshold is set to 50 rpm, the vehicle speed threshold is set to 10 km / h, and the second duration threshold is set to 2 seconds. The expression corresponding to the above multi-dimensional determination logic is as follows:

[0068] ;

[0069] In the formula, Indicates the speed difference between the two ends of the clutch; This indicates the set pure electric speed difference threshold. Indicates engine speed; This indicates the set engine speed threshold. Indicates a logical OR operation; Indicates the vehicle's speed; This indicates the set vehicle speed threshold. Indicates the duration of the abnormal combination state; This indicates the set second duration threshold; Represents logical AND operations.

[0070] Step S420: Report a Level 3 transmission system fault. Abnormal clutch engagement under pure electric conditions forces the drive motor to overcome engine pumping losses and mechanical friction, resulting in energy loss and potentially mechanical interference within the transmission system. Based on the severity of this condition, after confirming slippage, the clutch control unit reports a Level 3 transmission system fault to the system network. This level of system fault is defined as a critical fault response level. In this state, the vehicle issues a high-level warning to the driver, prompting them to pull over and suggesting contacting after-sales service.

[0071] Step S430: Execute the physical isolation command for the clutch and the global system error prevention command. Simultaneously with triggering a high-level fault report, the clutch control unit intervenes at the hardware drive level to prevent the fault from escalating. Unlike the operation of simply setting the control current to zero in parallel operation, the hardware intervention level in pure electric operation is more stringent. The clutch control unit physically disconnects the power supply circuit responsible for driving the controllable one-way electromagnetic clutch; specifically, this involves synchronously shutting down the high-end power supply circuit and the low-end control circuit of the clutch actuator coil.

[0072] In the underlying hardware architecture, if only one side of the control circuit is disconnected, the clutch may still unexpectedly become energized in the event of a single-point failure such as a short circuit to power or ground in the wiring harness. By simultaneously shutting down the power supply to the upper axle arm and the control terminal of the lower axle arm, the system achieves dual physical isolation, effectively preventing clutch mis-engagement caused by electronic component failure. Furthermore, the clutch control unit uploads the status parameters of this unexpected clutch engagement to the vehicle control unit. Upon receiving these status parameters, the vehicle control unit activates a global error prevention mechanism. During the remaining operating cycles of the current driving cycle, the vehicle control unit actively blocks engine start requests and prohibits the vehicle from switching to parallel operation mode, preventing damage to the transmission hardware caused by the intervention of a high-torque power source.

[0073] After completing the slippage diagnosis under any driving mode, the system needs to continuously track and record the health status of the clutch. The specific implementation process of step S50 includes the following steps:

[0074] Step S510: Perform auto-incrementing accumulation of the number of slippage conditions. When the control logic confirms that the clutch has slipped based on the aforementioned judgment conditions in the parallel state slippage diagnosis branch or the pure electric state slippage diagnosis branch, the clutch control unit performs a numerical accumulation operation on the slippage condition count variable in its internal random access memory.

[0075] As a preferred approach, to avoid the system repeatedly oscillating at the fault critical point, causing an abnormal surge in the count value, this embodiment introduces a state latching mechanism. Specifically, after a single diagnosis of slippage and the increment operation, the system immediately locks the corresponding fault status flag. In this state, even if subsequent operating conditions (such as residual speed fluctuations) again meet the slippage judgment conditions, the system will not repeat the count accumulation. The release condition for this latching state is set as follows: the clutch actuator coil completes a complete de-energization disengagement action and receives a closing energization command from the vehicle control unit again (i.e., completes a new physical reset), or the current vehicle driving cycle ends and the power is turned off. This mechanism not only filters out high-frequency oscillation false counts during a single slippage process but also ensures that multiple independent slippage events within the same driving cycle are not missed.

[0076] In this embodiment, resetting the accumulated number of slippage conditions typically requires maintenance personnel to actively issue a command to clear historical fault codes using external communication diagnostic equipment, distinguishing it from the release of anti-shake state latch within a single driving cycle. Furthermore, to ensure the stability of the underlying software, before executing the auto-increment, the system compares the current slippage condition count with the system's maximum physical storage limit for variables. If the limit has been reached, overflow protection is triggered, clamping the count to that maximum value. Through this mechanism, the system can objectively reflect the frequency of actual slippage faults occurring in the clutch during its lifespan.

[0077] Step S520: The number of slippage conditions is written to non-volatile memory for storage. After the controller is powered off, data in the conventional random access memory is at risk of being lost. To support subsequent cross-driving cycle evaluations, the accumulated data needs to be converted to non-volatile data. In this embodiment, when the driver disconnects the ignition switch and the vehicle begins the power-down process, the clutch control unit captures the sleep command sent by the vehicle communication network. During the controller's delayed power-down operation phase before the vehicle's main power relay is disconnected, the clutch control unit transfers the number of slippage conditions currently temporarily stored in the random access memory and writes it to the non-volatile memory built into the power domain controller.

[0078] As a preferred underlying hardware implementation, this non-volatile memory can be an electrically erasable programmable read-only memory or a data flash block within the microcontroller. The introduction of this physical medium ensures the effective retention of data even during external power interruptions, thereby providing reliable historical reference data for the hierarchical restriction strategy during subsequent vehicle power-on initialization. For the erasure, writing, and verification mechanisms of the microcontroller's underlying storage medium, those skilled in the art can refer to existing automotive electronic basic software architecture specifications, which are well-known technologies in the field and will not be elaborated upon here.

[0079] See attached document Figure 5After the slippage condition data is solidified and stored, to prevent the clutch from continuing to deteriorate after its physical lifespan has declined, the system introduces a long-term health assessment and takeover mechanism across driving cycles. The specific implementation process of step S60 includes the following steps:

[0080] Step S610: Extract the number of slippage conditions and perform a threshold comparison. When the vehicle performs the power-on initialization process or is in a normal operating cycle, the clutch control unit reads the accumulated number of slippage conditions from the non-volatile memory of the power domain controller. This historical data objectively characterizes the hardware wear degree of the controllable one-way electromagnetic clutch throughout its entire life cycle. The system compares this number of slippage conditions with a preset slippage life decay threshold.

[0081] As a preferred approach, the attenuation threshold is calibrated based on bench durability fatigue test data, representing the limit of slippage that the internal friction elements of the clutch can withstand before unreliable transmission occurs. In practical applications, depending on the material and thickness specifications of the clutch friction plates, this threshold is typically set between 10 and 50 times; for specific small electromagnetic clutches that are prone to ablation, this threshold can also be calibrated to 3 to 5 times.

[0082] Step S620: Implement a degraded operation and torque limiting protection strategy based on the non-over-limit state. When the comparison result shows that the number of slip-friction conditions is less than the set slip-friction life decay threshold, the system evaluates that the controllable one-way electromagnetic clutch hardware still has basic mechanical transmission capability. Under this condition, the vehicle control unit continues to allow the vehicle to switch to parallel operation mode.

[0083] Furthermore, to balance the power performance of a new vehicle with the protection of worn hardware, the system implements differentiated constraints based on whether the number of slippage conditions is zero: when the number of slippage conditions is zero, the system determines that the clutch is in a healthy state and does not impose additional restrictions on the transmission input torque; when the number of slippage conditions is greater than zero but less than the slippage life decay threshold, considering the existing wear accumulation, to slow down further aging of the clutch hardware, the clutch control unit broadcasts a transmission input torque limit request to the vehicle communication network. The vehicle control unit responds to this request by adjusting the target opening of the engine throttle or limiting the output current of the drive motor, thereby imposing an upper limit constraint on the transmission input torque transmitted to the transmission input terminal.

[0084] In this embodiment, the torque constraint is specifically implemented as follows: the system limits the maximum allowable output torque of the engine and drive motor in real time according to a preset derating factor (e.g., 80% of the rated torque at the current speed). This degraded operation mechanism reduces the stress load on the clutch at the moment of engagement and during transmission while retaining the vehicle's hybrid driving function, thereby reducing the probability of slippage recurring. For the closed-loop coordination and limiting control of engine and motor torque, those skilled in the art can refer to existing multi-power source torque distribution technology, which is well-known in the field and will not be elaborated here.

[0085] Step S630: Execute a global isolation and hierarchical restriction strategy based on the over-limit state. When the number of slip-friction cycles exceeds or equals the preset slip-friction life decay threshold, the system determines that the controllable one-way electromagnetic clutch has a high risk of failure. To prevent serious mechanical damage to the transmission system, the vehicle control unit will continuously prohibit the vehicle from using parallel drive function in the global control strategy until the historical fault record is actively cleared by maintenance personnel through external diagnostic equipment. To achieve smooth and safe takeover in different scenarios, the system designs differentiated edge condition protection logic based on the specific timing of the trigger judgment:

[0086] When the system detects an excessive slip count during the vehicle's power-on initialization phase, the clutch control unit reports a secondary fault in the transmission system to the system network. In this embodiment, the specific characteristics of this general secondary fault are defined as follows: the system actively disables the engine start command, forcing the vehicle to operate in pure electric mode, and simultaneously illuminates a maintenance indicator light on the instrument panel to alert the driver that the current power is limited.

[0087] During vehicle dynamic operation, if the system's counter accumulates due to a newly diagnosed transient slippage and triggers an over-limit judgment (i.e., the clutch mechanical wear has reached its design life limit), to ensure driving safety and avoid unexpected stalling, the system will only report a level-two fault in the transmission system to the network. Based on the level-two fault response strategy, the control system actively cuts off the clutch's underlying power supply circuit to safely disengage it, smoothly transitioning the vehicle's power output and permanently locking it in pure electric mode, while simultaneously prompting the driver to seek repair. This degradation handling method distinguishes between hardware lifespan expiration and sudden inability to disengage, avoiding the dangerous situation of the vehicle unexpectedly losing power or being forced to stop at high speeds due to the lifespan counter reaching its limit. Only when a pure electric inability to disengage fault as described in step S40 is detected in real time will the system report the highest severity level three fault and require the driver to immediately pull over.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for diagnosing slippage of a controllable one-way electromagnetic clutch, characterized in that, include: Acquire vehicle operating status parameters, including the vehicle hybrid status, speed difference between the two ends of the clutch, engine speed, and vehicle speed. The vehicle is determined to be in parallel or pure electric mode based on the overall vehicle hybrid status. When the vehicle is in the parallel state, the controllable one-way electromagnetic clutch is determined to be in a slipping condition based on the speed difference between the two ends of the clutch and the duration of the speed difference between the two ends of the clutch exceeding the limit. When the vehicle is in the pure electric state, the controllable one-way electromagnetic clutch is determined to be in the slipping condition by comprehensively judging the combination of the speed difference between the two ends of the clutch, the engine speed and the vehicle speed, as well as the duration of the combination of the states. After the slipping condition is identified, the number of slipping conditions is accumulated, and the number of slipping conditions is stored in non-volatile memory when the power is off. The number of slip-on conditions is read and compared with a preset slip-on life decay threshold. When the number of slip-on conditions is less than the slip-on life decay threshold, the parallel state is allowed and the transmission input torque is limited. When the number of slip-on conditions is greater than or equal to the slip-on life decay threshold, the parallel state is prohibited and a transmission system fault is reported.

2. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, Obtaining the speed difference between the two ends of the clutch includes: The speed of the clutch driving end and the speed of the clutch driven end are obtained, and the absolute value of the difference between the speed of the clutch driving end and the speed of the clutch driven end is taken as the speed difference between the two ends of the clutch.

3. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, When the vehicle is in the parallel state, determining whether the controllable one-way electromagnetic clutch is in the slipping condition includes: Determine whether the speed difference between the two ends of the clutch is greater than a set speed difference threshold and whether the duration reaches a set first duration threshold; If so, upon confirming that the controllable one-way electromagnetic clutch has entered the slipping condition, the energizing current output to the controllable one-way electromagnetic clutch actuator coil will be controlled to zero, and an unexpected separation status message will be transmitted to the vehicle control unit.

4. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, When the vehicle is in the pure electric state, determining whether the controllable one-way electromagnetic clutch is in the slippery condition includes: Determine whether the speed difference between the two ends of the clutch is less than a set pure electric speed difference threshold or whether the engine speed is greater than a set engine speed threshold, and the current vehicle speed is greater than a set vehicle speed threshold. If so, and the duration of the above judgment conditions reaches the set second duration threshold, it is confirmed that the controllable one-way electromagnetic clutch has entered the slipping and friction condition. The high-end power supply circuit and low-end control circuit of the controllable one-way electromagnetic clutch execution coil are synchronously shut off to block the engine start request.

5. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, The number of sliding friction cycles is accumulated, including: After confirming that the controllable one-way electromagnetic clutch has entered the slipping condition and completing the numerical accumulation operation of the number of slipping conditions, the corresponding fault status flag is locked to stop repeated accumulation. The fault status identifier is released when the controllable one-way electromagnetic clutch actuator coil completes a power-off separation action and receives a closing power-on command again, or when the current vehicle driving cycle ends and the power is turned off.

6. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 5, characterized in that, The cumulative number of slip-friction cycles also includes: Before performing the numerical accumulation operation, the current count value of the number of sliding friction conditions is extracted and compared with the set maximum physical storage limit of the variable; If the maximum physical storage limit of the variable is reached, the count value will be clamped to the maximum physical storage limit of the variable.

7. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, Upon power-off, the number of slippage cycles is stored in non-volatile memory, including: During the delayed power-down operation phase before the main power relay of the vehicle is disconnected, the number of slip-friction conditions temporarily stored in the random access memory is transferred and written into the non-volatile memory built into the power domain controller.

8. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, When the number of slip-fusing cycles is less than the slip-fusing life decay threshold, entering the parallel state and limiting the transmission input torque are permitted, including: When the number of slip-friction cycles is zero, no limit is imposed on the input torque of the transmission; When the number of slip-fusing conditions is greater than zero and less than the slip-fusing life decay threshold, an upper limit constraint is applied to the transmission input torque transmitted to the transmission input terminal according to a preset derating factor.

9. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, When the controllable one-way electromagnetic clutch is confirmed to be in the slipping condition, if the vehicle is in the parallel state, a first-level fault of the transmission system is reported. If the vehicle is in the pure electric state, report a level three fault in the transmission system. When the number of slip-and-flip conditions is greater than or equal to the slip-and-flip life decay threshold, the reporting of the transmission system fault specifically involves reporting a level-two fault in the transmission system and forcing the vehicle to lock into pure electric operation.

10. The method for diagnosing slippage of a controllable one-way electromagnetic clutch according to claim 1, characterized in that, Determining whether a vehicle is in parallel or pure electric mode based on its hybrid status includes: The status flag bit variable representing the vehicle's target driving mode, broadcast by the vehicle control unit, is read, and the current parallel state or pure electric state of the vehicle is identified by comparing the status flag bit variable.

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