A power cycle suppression method and system for an HMCVT

Abstract

The application provides a power cycle suppression method and system for an HMCVT, and belongs to the technical field of transmission drive design; the method comprises the following steps: when no power cycle occurs, maintaining normal operation mode and monitoring the cycle energy in real time; when the cycle energy exceeds a trigger threshold, sequentially performing power cycle suppression through three-level mode control including a soft processing mode, a bypass flow guide mode and a pure mechanical mode; the three-level modes are executed in sequence and independently, and only when the current mode fails, the next-level mode is enabled for control. The application can identify the power cycle in real time, and actively regulate and utilize the cycle energy through the combination of structure and control, thereby significantly improving the power cycle suppression effect of the HMCVT.

Description

Technical Field

[0001] This invention belongs to the field of transmission design technology, and particularly relates to a power cycle suppression method and system for HMCVT. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In existing HMCVT systems, the hydraulic branch, mainly composed of a hydraulic pump and a hydraulic motor, performs the speed regulation function. It continuously changes the transmission ratio by altering the displacement, and simultaneously couples with the mechanical path to complete power synthesis. However, due to energy conversion losses inherent in hydraulic systems, and the power distribution between the mechanical and hydraulic paths depending on operating conditions, energy backflow can easily occur between the two paths when the system operates under certain specific conditions. This means that some power circulates within the system without being effectively output; this phenomenon is called power circulation or power backflow.

[0004] In existing technologies, the power cycle problem in HMCVT is mostly alleviated to some extent by optimizing displacement control strategies or adjusting transmission structure parameters, but the following shortcomings still exist: (1) Existing control methods are mostly based on static mapping or simple threshold judgment, which makes it difficult to identify the power cycle state in a timely and accurate manner, and easily leads to control lag or misjudgment.

[0005] (2) Existing solutions lack effective means of handling circulating energy. Once power backflow occurs, it is often converted into heat energy through internal system consumption, which leads to decreased efficiency and increased system temperature. In addition, under complex operating conditions, it is difficult to fundamentally interrupt the power circulation path by simply relying on parameter adjustment. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a power cycle suppression method and system for HMCVT, which can identify power cycles in real time and actively regulate and utilize cycle energy through a combination of structure and control, thereby significantly improving the power cycle suppression effect for HMCVT.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of the present invention provides a power cycle suppression method for HMCVT.

[0008] A power cycling suppression method for HMCVT includes: When no power cycle occurs, the HMCVT maintains normal operating mode and monitors the change in cycle energy in real time. That is, by acquiring the hydraulic power and mechanical power of the HMCVT in the hydraulic path and mechanical path respectively, the cycle power is calculated; and the cycle power within a preset time window is accumulated as the cycle energy. When the cycle energy exceeds the trigger threshold, power cycle suppression is performed sequentially through a three-level mode control system, which includes a soft processing mode, a bypass flow mode, and a pure mechanical mode. The three levels of modes are executed in sequence and individually, and the next level of mode is activated for control only when the current mode fails.

[0009] Furthermore, the calculation of the cycle power includes: performing exponential filtering on the hydraulic power and mechanical power; if the filtered hydraulic power and mechanical power have the same sign, the cycle power is zero, that is, no power cycle has occurred; when the hydraulic power and mechanical power have opposite signs, the smaller of the absolute value of the hydraulic power and the absolute value of the mechanical power is determined as the cycle power.

[0010] Furthermore, the circulating power within the preset time window is accumulated as circulating energy, which is expressed as: ; in, This represents the cumulative cyclic energy obtained; Indicates the current moment. Indicates the length of the preset time window; Indicates cycle power. It is the integral variable.

[0011] Furthermore, the soft processing mode includes: suppressing power cycling by changing the instantaneous output of the hydraulic pump and hydraulic motor, and continuously monitoring the cycling energy and pressure pulsation during the suppression process; if the cycling energy drops to a preset safe range within a preset time period, the suppression operation ends; if the cycling energy does not drop to a safe range within the preset time period, the mode switches from soft processing mode to bypass diversion mode.

[0012] Furthermore, the bypass flow guiding mode includes: opening the bypass valve connected in parallel to the oil line between the hydraulic pump and the hydraulic motor to guide the energy flow on the hydraulic path to the accumulator for storage, so as to prevent backflow to the mechanical path; in the bypass flow guiding mode, when either the accumulator reaches a preset upper limit or a continuous high-amplitude backflow is detected, the mode is switched to pure mechanical mode.

[0013] Furthermore, the pure mechanical mode includes: disconnecting the engine's power connection in the hydraulic path via a clutch, fixing the sun gear on the planetary gear mechanism via a lock, so that the engine's power is directly output to the outside through the planet carrier of the planetary gear mechanism; at the same time, setting the displacement of the hydraulic pump to a safe no-load value and shutting off the bypass charging action.

[0014] A second aspect of the present invention provides a power cycle suppression system for HMCVT.

[0015] A power cycle suppression system for HMCVT includes: an HMCVT drive mechanism, a bypass energy storage module, a sensor unit, and a controller; The HMCVT transmission mechanism includes an engine, a hydraulic pump, a hydraulic motor, a clutch, a lock, and a planetary gear mechanism for power confluence. The bypass energy storage module includes a bypass valve, a check valve, an accumulator, and a discharge valve connected in parallel to the hydraulic oil circuit via a bypass branch. The sensor unit is used to simultaneously acquire the hydraulic power in the hydraulic path and the mechanical power in the mechanical path; The controller is configured to: calculate the circulating power based on the hydraulic power and mechanical power; accumulate the circulating power within a preset time window as circulating energy; when the circulating energy exceeds a trigger threshold, suppress the power circulation through a three-level mode control including a soft processing mode, a bypass flow mode, and a pure mechanical mode; wherein the three levels of modes are executed sequentially and individually, and the next level of mode is activated for control only when the current mode fails.

[0016] Furthermore, in the hydraulic path, the engine input is connected to the hydraulic pump through the first gear set, and the hydraulic pump is connected to the hydraulic motor through the hydraulic oil circuit; a bypass branch is provided in the hydraulic oil circuit, and the bypass branch is connected to the accumulator through the bypass valve and the check valve, and then merges into the hydraulic oil circuit through the energy release valve.

[0017] Furthermore, the hydraulic motor is connected to the sun gear on the planetary gear mechanism via a second gear set, and the sun gear is equipped with a locking device that can lock the rotation.

[0018] Furthermore, in the mechanical path, the engine is directly connected to the gear ring on the planetary gear mechanism. The power from both the mechanical and hydraulic paths first merges through the planetary gear mechanism and then outputs power outward through the planetary carrier.

[0019] The above one or more technical solutions have the following beneficial effects: (1) This invention acquires the power signals of the hydraulic and mechanical paths of the HMCVT in real time and uses exponential filtering to eliminate instantaneous fluctuation interference. Then, it accurately determines the magnitude of the circulating power based on the similarity or difference in power signs. When the power signs of the two paths are opposite, the smaller absolute value is used as the circulating power, avoiding misjudgment. Furthermore, this invention accumulates and integrates the circulating power within a preset time window to obtain the circulating energy as the basis for judgment. This dual mechanism of "instantaneous power sign judgment + window energy accumulation" can smooth power transients and reflect the energy accumulation effect, thereby timely and accurately capturing the occurrence and severity of power cycles. It effectively overcomes the control failure problem caused by lag or misjudgment in existing methods, providing reliable triggering conditions for subsequent graded suppression.

[0020] (2) This invention designs a three-level progressive control strategy including a soft processing mode, a bypass flow mode, and a pure mechanical mode. In the bypass flow mode, by opening the bypass valve connected in parallel between the hydraulic pump and the motor, the circulating energy that would otherwise flow back and be converted into heat is actively guided to the accumulator for storage, instead of being dissipated as heat within the system. This significantly reduces system temperature rise and improves transmission efficiency. Furthermore, the stored energy can be released back into the hydraulic path through the energy release valve at appropriate times to assist in driving, achieving energy recovery and utilization that "turns waste into treasure." When the bypass flow mode is still insufficient to eliminate severe power cycling, the pure mechanical mode disconnects the power connection of the hydraulic path through the clutch and uses a lock to fix the sun gear of the planetary gear mechanism, ensuring that engine power is transmitted only through the mechanical path, thus structurally breaking the physical path of power cycling. This invention organically combines the energy recovery structure with the mechanical cut-off mechanism, solving the problem of disordered dissipation of circulating energy and compensating for the insufficient suppression capability of simple parameter adjustment under complex operating conditions, comprehensively improving the energy efficiency, reliability, and adaptability of the HMCVT system.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a flowchart of a power cycle suppression method for HMCVT according to Embodiment 1 of the present invention.

[0024] Figure 2 This is a structural diagram of the power cycle suppression system in Embodiment 1 of the present invention.

[0025] In the diagram: 1. Engine; 2. Hydraulic pump; 3. Hydraulic motor; 4. Clutch; 5. Locking device; 6. Bypass valve; 7. Check valve; 8. Accumulator; 9. Energy release valve; 10. First gear; 11. Second gear; 12. Third gear; 13. Fourth gear; 14. Sun gear; 15. Ring gear; 16. Planetary carrier; 17. Hydraulic circuit. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0028] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0029] Example 1 This embodiment discloses a power cycle suppression method for HMCVT.

[0030] like Figure 1 As shown, a power cycling suppression method for HMCVT includes: When no power cycle occurs, the HMCVT maintains normal operating mode and monitors the change in cycle energy in real time. That is, by acquiring the hydraulic power and mechanical power of the HMCVT in the hydraulic path and mechanical path respectively, the cycle power is calculated; and the cycle power within a preset time window is accumulated as the cycle energy. When the cycle energy exceeds the trigger threshold, power cycle suppression is performed sequentially through a three-level mode control system, which includes a soft processing mode, a bypass flow mode, and a pure mechanical mode. The three levels of modes are executed in sequence and individually, and the next level of mode is activated for control only when the current mode fails.

[0031] Based on the above method, this invention can identify power cycles in real time and actively regulate and utilize cycle energy through a combination of structure and control, significantly improving the power cycle suppression effect on HMCVT. To facilitate understanding of the technical solution of this invention, the specific implementation methods of this invention will be further explained and described below.

[0032] The present invention provides a power cycle suppression method for HMCVT, specifically for applications such as... Figure 2The power cycle suppression system shown adopts a bypass energy storage structure design. The power cycle suppression system includes: an HMCVT transmission mechanism, a bypass energy storage module, a sensor unit, and a controller.

[0033] The HMCVT transmission mechanism includes an engine 1, a hydraulic pump 2, a hydraulic motor 3, a clutch 4, a lock-up device 5, and a planetary gear mechanism for power confluence; the bypass energy storage module includes a bypass valve 6, a check valve 7, an accumulator 8, and a release valve 9 connected in parallel to the hydraulic circuit 17 via a bypass branch; the sensor unit is used to simultaneously acquire the hydraulic power in the hydraulic path and the mechanical power in the mechanical path; the controller is used to calculate the circulating power based on the hydraulic power and the mechanical power; and accumulate the circulating power within a preset time window as circulating energy; when the circulating energy exceeds the trigger threshold, power circulation suppression is performed sequentially through a three-level mode control including a soft processing mode, a bypass diversion mode, and a pure mechanical mode; wherein, the three levels of modes are executed sequentially and individually, and the next level mode is activated for control only when the current mode fails.

[0034] In the hydraulic path, the engine input is connected to the hydraulic pump through the first gear set, that is, the first gear 10 (with a clutch 4 on the first gear) is connected to the second gear 11, and the second gear 11 is connected to the hydraulic pump 2; the hydraulic pump 2 is connected to the hydraulic motor 3 through the hydraulic oil circuit 17.

[0035] Meanwhile, a bypass branch in the hydraulic circuit connects to the accumulator 8 via bypass valve 6 and check valve 7, and then merges into the hydraulic circuit via discharge valve 9. The hydraulic motor 3 is connected to the sun gear 14 of the planetary gear mechanism via the second gear set, that is, the third gear 12 and the fourth gear 13 are connected to the sun gear 14 of the planetary gear mechanism. The sun gear 14 has a locking device 5 that can lock the rotation.

[0036] In the mechanical path, the engine 1 is directly connected to the gear ring 15 on the planetary gear mechanism. The power from the mechanical path and the hydraulic path is combined through the planetary gear mechanism and then output to the outside through the planet carrier 16.

[0037] Based on the above systematic structural design, the HMCVT maintains normal operating mode and monitors cycle energy changes in real time when no power cycle occurs.

[0038] When the system is in normal operation, the controller drives the pump displacement and motor output using a normal energy management strategy, allocating power according to the target for the hydraulic and mechanical paths. The execution logic of the normal energy management strategy includes: the controller first determines the target transmission ratio based on the target vehicle speed and current output shaft speed, and calculates the required output power of the system based on the target traction force or load torque; subsequently, the controller determines the target power for the hydraulic path and the mechanical path based on the engine's efficient operating range, hydraulic system efficiency, and the allowable displacement range of the hydraulic pump and hydraulic motor. After determining the target power allocation, the controller converts the hydraulic path target power into the target displacement of the hydraulic pump and the hydraulic motor. Based on the hydraulic path target power, the controller determines the required output flow of the hydraulic pump and further obtains the target displacement of the hydraulic pump. Simultaneously, based on the target transmission ratio and the required torque of the sun gear, the controller determines the target displacement and target output torque of the hydraulic motor. The controller sends control commands to the hydraulic pump displacement adjustment mechanism and the hydraulic motor displacement adjustment mechanism, causing the hydraulic pump output flow and hydraulic motor output torque to gradually approach the target values. At the same time, the controller adjusts the engine operating state according to the mechanical path target power, ensuring that the engine speed and output torque are always within the range of highest fuel economy. A portion of the engine's output power is directly transmitted to the ring gear of the planetary gear mechanism via a mechanical path, while another portion is transmitted to the hydraulic pump 2 via the first gear 10 and the second gear 11, entering the hydraulic path. The controller coordinates the engine speed, hydraulic pump displacement, and hydraulic motor displacement to ensure that the input power of the ring gear 15 and the sun gear 14 meets the target power distribution relationship, thereby ensuring that the output speed and torque of the planetary carrier 16 meet the overall target vehicle speed and power requirements. This control method achieves both optimal fuel economy of the engine at all times and continuously variable transmission (CVT) by adjusting the hydraulic system displacement to meet vehicle speed and power requirements. Furthermore, during the execution of the normal energy management strategy, the bypass diversion module is essentially inactive, and components such as the bypass valve 6, energy release valve 9, and accumulator are essentially closed.

[0039] The controller reads the corresponding sensor unit at a sampling period of 30ms to collect hydraulic power. With mechanical power ;in, Indicates the hydraulic pressure of the hydraulic motor. Indicates hydraulic oil flow rate; Indicates the gear ring torque. This represents the rotational speed of the gear ring. Then, an exponential filter is applied to the hydraulic power and mechanical power, i.e.: ; in, The sampled value at the current moment. This is the filtered result. This represents the filtered result of the sampled value from the previous moment; The value of the filter coefficient is typically between 0.2 and 0.5. The main function of exponential filtering is to reduce the impact of instantaneous power fluctuations on the measurement results.

[0040] If the filtered hydraulic power and mechanical power have the same sign, then the circulating power is zero, meaning no power circulation has occurred; when the hydraulic power... and mechanical power If the signs are opposite, then the smaller of the absolute value of the hydraulic power and the absolute value of the mechanical power is determined as the cycle power, that is: ; in, This indicates the cycle power.

[0041] The circulating power within a preset time window is accumulated as circulating energy, which is expressed as: ; in, This represents the cumulative cyclic energy obtained; Indicates the current moment. This indicates the length of the preset time window, typically ranging from 0.3s to 1s. It is the integral variable.

[0042] Simultaneously, the bypass valve is kept closed by the controller, meaning the entire bypass system is inactive; the accumulator is at standby pressure, and its pressure status is monitored in real time. If the circulating energy exceeds the trigger threshold... If the duration exceeds the expected time, the system switches from normal operating mode to soft processing mode. In this embodiment, the trigger threshold is set to 3 kJ, and the expected time is set to 0.5 s. If no trigger is triggered, normal control continues and operating data is recorded for self-learning of the threshold.

[0043] When the circulating energy remains at zero (i.e., in normal operating mode), since the bypass system is not working, with clutch 4 engaged, part of the engine's energy is transmitted to the hydraulic path via the first gear 10 and the second gear 11, while the other part is directly transmitted to the ring gear 15 in the planetary gear mechanism as the energy input for the mechanical path. The energy from the hydraulic path drives the hydraulic pump to rotate, and the hydraulic pump then drives the hydraulic motor to rotate via the hydraulic oil circuit 17. The hydraulic motor in turn drives the sun gear 14 in the planetary gear mechanism to rotate. In this way, the mechanical path energy from the ring gear 15 and the hydraulic path energy from the sun gear 14 are combined through the planetary gear mechanism and then output as power through the planet carrier.

[0044] Furthermore, when the cycle energy exceeds the trigger threshold, power cycle suppression is achieved through a three-level control system comprising a soft processing mode, a bypass diversion mode, and a pure mechanical mode. The three levels of modes are executed sequentially and individually, with the next level activated only when the current mode fails. This can be implemented using the following method: 1) Soft processing mode.

[0045] In this mode, the cycle energy exceeds the trigger threshold but is still in the initial stage, that is, it is in a processing state where power cycling has occurred but the degree of cycling is not yet serious.

[0046] To address this, a rapid parameter adjustment strategy is implemented through the controller. The aim is to suppress power cycling by altering the instantaneous output of the hydraulic pump and hydraulic motor. Specifically, in this mode, the operation of each component is essentially the same as in normal operation, except that the hydraulic pump's displacement needs to be slowly reduced within 200ms, while the target displacement of the hydraulic motor is reduced as needed. At this time, the transmission mechanism loses some of its continuously variable transmission (CVT) capability, which is compensated for by changes in engine speed; that is, the engine needs to adjust its speed to meet vehicle speed requirements. In other words, in normal operation, the engine speed remains essentially constant, and the CVT function is achieved through continuous changes in the displacement of the hydraulic pump and hydraulic motor. However, in soft-processing mode, this continuous displacement change process needs to be interrupted, and the resulting speed difference is adjusted by the engine speed. Otherwise, it is no different from normal operation.

[0047] During the suppression process, the circulating energy and pressure pulsation are continuously monitored. If the circulating energy drops below the preset safety range (1kW) within a preset time period, the suppression operation ends and recovers after a short period of time (about 0.5s). If the circulating energy does not drop to the safety range within the preset time period, the system switches from soft processing mode to bypass diversion mode.

[0048] The advantages of soft processing are that it has little impact on operational performance and low implementation cost. However, its disadvantages are that it has limited effect on medium to high amplitude continuous backflow and will affect the continuously variable transmission function of the vehicle. Therefore, it is only used as the first priority suppression method.

[0049] 2) Bypass diversion mode.

[0050] The bypass flow guiding mode is characterized by a bypass branch set in the hydraulic oil line from the hydraulic pump to the hydraulic motor. The function of this bypass branch is to guide the energy flow of the hydraulic path to the accumulator for storage, so as to be used later. The key to realizing the bypass flow guiding mode is the bypass energy storage module designed in this invention, which is independent of the HMCVT transmission mechanism. The bypass energy storage module is connected in parallel between the hydraulic pump and hydraulic motor circuits. The electrically controlled bypass valve 6 is located at the branch inlet and is connected to the check valve 7 and the hydraulic accumulator. At the same time, pressure sensors and temperature sensors are arranged at the accumulator.

[0051] The control objective of the bypass flow mode is to divert the hydraulic energy that is about to form a cycle into the accumulator to prevent it from flowing back into the mechanical path. In bypass flow mode, after the controller determines that there is a tendency for the hydraulic path to flow back into the mechanical path, it controls the bypass valve 6 to open at a small opening, so that part of the high-pressure oil at the output end of the hydraulic pump does not enter the hydraulic motor, but instead enters the bypass branch through the bypass valve 6. This oil flows into the accumulator 8 through the check valve 7, which is used to prevent the pressurized oil in the accumulator from flowing back to the hydraulic pump side. As the high-pressure oil enters the accumulator, the energy that might have been transmitted to the sun gear 14 through the hydraulic motor, the third gear 12, and the fourth gear 13 and flowed back with the mechanical power on the gear ring 15 side is converted into pressure energy stored in the accumulator. At this time, the energy release valve 9 remains closed to avoid interference with the energy storage process. The controller adjusts the opening of the bypass valve 6 according to the accumulator pressure and the bypass flow to stabilize the power convergence at the planetary gear mechanism, thereby suppressing the power cycle from the hydraulic path to the mechanical path.

[0052] Furthermore, once the transmission mechanism enters the bypass flow mode, the controller gradually performs bypass charging.

[0053] First, open the bypass valve with a small opening and read the bypass flow rate. Calculate the target power to charge the accumulator; this amount is mainly based on the current pressure of the accumulator. And temperature are calculated. Specifically, the target flow rate is set based on the target power as follows: ; in, Indicates the target traffic; Indicates the target power. This indicates the hydraulic pressure of the hydraulic pump.

[0054] Subsequently, by adjusting the opening of the bypass valve, the bypass flow rate is made as close as possible to the target flow rate. At the same time, the rate of increase of the current pressure of the accumulator is monitored. If the rate of increase exceeds the preset threshold, the opening of the bypass valve is immediately reduced to prevent impact.

[0055] During the charging process, if the accumulator reaches its preset upper limit (i.e., the internal pressure of the accumulator approaches its maximum pressure) or a continuous high-amplitude backflow is detected, the bypass valve will be gradually closed, entering a pure mechanical mode. Simultaneously, the charging energy and time can be recorded for accumulator pressure management and future parameter adjustments.

[0056] During periods when the transmission mechanism is not in a power cycle, i.e., under the current operating condition where energy flows in the same direction in both the hydraulic and mechanical paths, the accumulator can release its stored energy into the hydraulic path to assist the hydraulic motor in rotating and providing the required torque. This reduces energy consumption in the current hydraulic path, thereby reducing the burden on the engine and achieving energy savings. Essentially, energy that would otherwise be wasted in the power cycle is reused in the normal operation of the transmission system. The correct release of the accumulator's pressure energy is mainly achieved by the energy release valve, which is gradually adjusted by the controller to release pressure energy into the hydraulic circuit.

[0057] The advantage of the bypass diversion mode is that it can quickly intercept a large amount of circulating energy and recover and reuse it at the system level. The disadvantage is that it increases the hardware and protection requirements such as accumulators, and the hydraulic path structure becomes more complicated, which may lead to unstable operation of the hydraulic system.

[0058] 3) Pure mechanical mode.

[0059] In pure mechanical mode, the controller issues commands to the clutch and lock-up device. Specifically, clutch 4 disengages, causing the engine and hydraulic path to lose power connection, and lock-up device 5 engages. Consequently, the energy output from the engine cannot be transmitted to the hydraulic path via the first gear 10 and the second gear 11. Components such as the hydraulic pump, hydraulic motor, and accumulator in the bypass system all stop operating. The sun gear 14 in the planetary gear mechanism is also fixed by lock-up device 5. The energy output from the engine directly drives the ring gear 15 in the planetary gear mechanism to rotate, which in turn drives the planet carrier 16 to rotate. Therefore, the engine's power is essentially output directly through the planet carrier of the planetary gear mechanism. In this mode, the controller needs to set the pump displacement to a safe no-load value and disable the bypass charging operation.

[0060] Simultaneously, monitor system stability. If backflow disappears, pump displacement and energy management can be gradually restored. In addition, the transmission efficiency of the entire transmission system is actually the highest in pure mechanical mode. If the current operating conditions of the vehicle have a low demand for continuously variable transmission, such as when a tractor is operating smoothly, pure mechanical mode can also be activated to improve transmission efficiency.

[0061] This mode is a last resort and can completely block the power cycle at the structural level. However, it should be avoided except in special circumstances. First, the pure mechanical mode does not have the function of shifting gears. Second, it will have an adverse effect on the driving experience or the lifespan of the components.

[0062] Example 2 This embodiment discloses a power cycle suppression system for HMCVT.

[0063] A power cycle suppression system for HMCVT includes: an HMCVT drive mechanism, a bypass energy storage module, a sensor unit, and a controller; The HMCVT transmission mechanism includes an engine, a hydraulic pump, a hydraulic motor, a clutch, a lock, and a planetary gear mechanism for power confluence. The bypass energy storage module includes a bypass valve, a check valve, an accumulator, and a discharge valve connected in parallel to the hydraulic oil circuit via a bypass branch. The sensor unit is used to simultaneously acquire the hydraulic power in the hydraulic path and the mechanical power in the mechanical path; The controller is configured to: calculate the circulating power based on the hydraulic power and mechanical power; accumulate the circulating power within a preset time window as circulating energy; when the circulating energy exceeds a trigger threshold, suppress the power circulation through a three-level mode control including a soft processing mode, a bypass flow mode, and a pure mechanical mode; wherein the three levels of modes are executed sequentially and individually, and the next level of mode is activated for control only when the current mode fails.

[0064] Furthermore, in the hydraulic path, the engine input is connected to the hydraulic pump through the first gear set, and the hydraulic pump is connected to the hydraulic motor through the hydraulic oil circuit; a bypass branch is provided in the hydraulic oil circuit, and the bypass branch is connected to the accumulator through the bypass valve and the check valve, and then merges into the hydraulic oil circuit through the energy release valve.

[0065] Furthermore, the hydraulic motor is connected to the sun gear on the planetary gear mechanism via a second gear set, and the sun gear is equipped with a locking device that can lock the rotation.

[0066] Furthermore, in the mechanical path, the engine is directly connected to the gear ring on the planetary gear mechanism. The power from both the mechanical and hydraulic paths first merges through the planetary gear mechanism and then outputs power outward through the planetary carrier.

[0067] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A power cycling suppression method for HMCVT, characterized in that, include: The HMCVT maintains normal operating mode and monitors the change in cycle energy in real time when no power cycle occurs. That is, the cycle power is calculated by acquiring the hydraulic power and mechanical power of the HMCVT in the hydraulic path and mechanical path respectively. The circulating power within a preset time window is accumulated as circulating energy. The calculation of circulating power includes: exponential filtering of the hydraulic power and mechanical power; if the filtered hydraulic power and mechanical power have the same sign, the circulating power is zero, meaning no power circulation has occurred; if the hydraulic power and mechanical power have opposite signs, the smaller of the absolute values ​​of the hydraulic power and the mechanical power is determined as the circulating power; the circulating power within the preset time window is accumulated as circulating energy, which is expressed as: ； in, This represents the cumulative cyclic energy obtained; Indicates the current moment. Indicates the length of the preset time window; Indicates cycle power. For integration variables; When the circulating energy exceeds the trigger threshold, power cycle suppression is achieved through a three-level control system comprising a soft processing mode, a bypass flow mode, and a pure mechanical mode. The three levels of modes are executed sequentially and individually, with the next level activated only when the current mode fails. The soft processing mode includes: suppressing power cycle by altering the instantaneous output of the hydraulic pump and hydraulic motor, and continuously monitoring circulating energy and pressure pulsations during the suppression process. If the circulating energy decreases to a preset safe range within a preset time period, the suppression operation ends. If the circulating energy does not decrease to a safe range within the preset time period, the system switches from the soft processing mode to the bypass flow mode.

2. The power cycling suppression method for HMCVT as described in claim 1, characterized in that, The bypass flow guiding mode includes: opening the bypass valve connected in parallel to the oil line between the hydraulic pump and the hydraulic motor to guide the energy flow on the hydraulic path to the accumulator for storage, so as to prevent backflow to the mechanical path; in the bypass flow guiding mode, when either the accumulator reaches the preset upper limit or a continuous high-amplitude backflow is detected, the mode is switched to pure mechanical mode.

3. The power cycling suppression method for HMCVT as described in claim 1, characterized in that, The pure mechanical mode includes: disconnecting the engine's power connection in the hydraulic path via a clutch, fixing the sun gear on the planetary gear mechanism via a lock, so that the engine's power is directly output to the outside through the planet carrier of the planetary gear mechanism; at the same time, setting the displacement of the hydraulic pump to a safe no-load value and shutting off the bypass charging action.

4. A power cycle suppression system for HMCVT, employing the power cycle suppression method as described in any one of claims 1-3, characterized in that, include: HMCVT drive mechanism, bypass energy storage module, sensor unit and controller; The HMCVT transmission mechanism includes an engine, a hydraulic pump, a hydraulic motor, a clutch, a lock, and a planetary gear mechanism for power confluence. The bypass energy storage module includes a bypass valve, a check valve, an accumulator, and a discharge valve connected in parallel to the hydraulic oil circuit via a bypass branch. The sensor unit is used to simultaneously acquire the hydraulic power in the hydraulic path and the mechanical power in the mechanical path; The controller is configured to: calculate the circulating power based on the hydraulic power and mechanical power; accumulate the circulating power within a preset time window as circulating energy; when the circulating energy exceeds a trigger threshold, suppress the power circulation through a three-level mode control including a soft processing mode, a bypass flow mode, and a pure mechanical mode; wherein the three levels of modes are executed sequentially and individually, and the next level of mode is activated for control only when the current mode fails.

5. A power cycling suppression system for HMCVT as described in claim 4, characterized in that, In the hydraulic path, the engine input is connected to the hydraulic pump through the first gear set, and the hydraulic pump is connected to the hydraulic motor through the hydraulic oil circuit; a bypass branch is provided in the hydraulic oil circuit, and the bypass branch is connected to the accumulator through the bypass valve and the check valve, and then merges into the hydraulic oil circuit through the energy release valve.

6. A power cycle suppression system for HMCVT as described in claim 4, characterized in that, The hydraulic motor is connected to the sun gear on the planetary gear mechanism via a second gear set, and the sun gear is equipped with a locking device that can lock the rotation.

7. A power cycle suppression system for HMCVT as described in claim 4, characterized in that, In the mechanical path, the engine is directly connected to the gear ring on the planetary gear mechanism. The power from both the mechanical and hydraulic paths first merges through the planetary gear mechanism and then outputs power outward through the planet carrier.

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