A method and apparatus for controlling the speed of an excavator engine

Abstract

This invention discloses a method and device for controlling the engine speed of an excavator. The method includes: real-time acquisition of engine load rate data and hydraulic system pump inlet pressure data; performing time window statistics on the load rate data to quantify the current power demand state into high load, low load, or normal state; when a high load state is determined, executing a first acceleration control strategy, calculating the target speed based on the current speed and load rate, and controlling the acceleration; when a non-high load state is determined, monitoring the hydraulic system pump inlet pressure change rate, and if the pressure change rate exceeds a threshold and the hydraulic system pump inlet pressure exceeds a preset value, triggering a second acceleration control strategy for pressure following compensation; when a low load state is determined or the speed exceeds a preset exit speed, exiting the acceleration control. This invention can identify load rate trends and, combined with the hydraulic system pump inlet pressure status, intervene in stages to achieve stable control and intelligent idling energy saving under complex loads.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, specifically to a method and device for controlling the engine speed of an excavator. Background Technology

[0002] Excavators are widely used construction machinery, commonly used in earthmoving, mining, and other fields. The operating conditions of excavators are complex and varied. Industry research on their operating conditions mainly focuses on excavation, slope repair, and crushing, but research on excavator applications in agriculture and forestry is relatively limited. In agriculture and forestry, lifting (boom lifting) and grabbing (material loading and unloading) operations are particularly common. In lifting operations, the hydraulic system needs to provide a large flow rate instantaneously to lift heavy objects, causing a sharp increase in engine load. If the response is not timely, the engine speed can easily drop sharply or even stall. In grabbing operations, due to the frequent opening and closing of the gripper and the accompanying rotary motion, the hydraulic system experiences periodic pressure shocks, resulting in severe fluctuations in pump pressure. This places extremely high demands on the engine's transient response speed and stability.

[0003] In existing technologies, engine speed control in construction machinery often employs static mapping based on the accelerator pedal or simple PID feedback control, which struggles to cope with drastic changes in load rate. Regarding automatic idling technology, patent CN200710020360.8 discloses an automatic idling control method for excavator engines. This method utilizes a two-stage speed reduction (high idle, low idle) and two-stage speed increase control strategy based on pilot pressure detection to address the energy consumption problem caused by large fluctuations in engine speed in traditional idling control. The technical solution is as follows: the secondary target engine speed is set 50-300 rpm lower than the target speed during operation; the high idle speed is set 300-500 rpm higher than the low idle speed; and the pilot pressure threshold is set to 5-20 Bar. During operation, when the pilot pressure is zero and remains at zero for a first idle time, the engine adjusts to a high idle state; after maintaining this position for a second idle time, it adjusts to a low idle state. This two-stage speed reduction overcomes the drawbacks of high energy consumption caused by large fluctuations in engine speed, achieving a balance between engine power, economy, and speed. Patent CN200520050630.6 discloses an automatic idling device for a small hydraulic excavator, which achieves automatic idling by reducing the throttle during standby and quickly resetting it during operation through a mechanical structure that connects a small hydraulic cylinder in series with the throttle cable. However, none of the above patents have solved the technical problems of ensuring the smoothness of speed recovery after disengaging from automatic idling and the inability of the engine's transient response speed to meet the requirements of real-time operating conditions under drastic load changes.

[0004] Hitachi Construction Machinery's patent CN200480000809.9 (Chinese Publication No. CN1701172A) discloses an engine control device for construction machinery. This device includes a pressure sensor, a position sensor, a target speed correction value calculation unit, and a correction value addition unit. It calculates the target speed NR2 for control based on changes in state variables, causing it to rise from the input target speed NR1 and then slowly return to the target speed NR1. The target fuel injection quantity is calculated based on the target speed NR2, and the fuel injection quantity is controlled accordingly. This scheme uses a state variable detection mechanism to monitor state variables related to the hydraulic pump load in real time and calculates a preset value higher than the target speed, pre-storing sufficient torque and power for upcoming high loads. After the load stabilizes, the system controls the engine speed to smoothly and slowly return to the target speed. However, this scheme triggers the system only upon detecting instantaneous changes, which can easily lead to misoperation. Furthermore, the exit from the compensation state occurs after a period of time, failing to reflect actual working conditions and making it unsuitable for continuous high-load working conditions such as lifting and grabbing operations.

[0005] Therefore, in order to meet the needs of the agricultural and forestry industries, especially the lifting and grabbing conditions with various load characteristics such as continuous high load and pressure shock, there is a need for an automatic speed control method that can identify load rate trends and intervene in stages in combination with the hydraulic system pump port pressure status. This method would fill the technical gap between continuous high load response and pressure shock resistance under lifting and grabbing conditions, and achieve intelligent automatic idling in non-working states, thus achieving a balance between power and economy. Summary of the Invention

[0006] The core of this invention lies in: using time window statistics of load rate to identify sustained high load conditions, using the rate of change of hydraulic system pump inlet pressure to predict pressure shock conditions, and performing segmented speed-up control based on these two conditions. Any technical solution that achieves the same function and effect using essentially the same means (i.e., collecting load and pressure, performing time window statistics and rate of change analysis, and segmented speed-up) falls within the protection scope of this invention.

[0007] To achieve the above objectives, the present invention provides the following technical solution: 1. Load factor status determination Engine load rate data is collected within a preset time window (which can be set according to engine model and response requirements). The average load rate within the window is calculated and compared with preset rise and fall thresholds to quantify the current power demand status. If the average value is greater than the rising threshold (different values ​​are used for different models, which can be determined by taking the high quantile value from the distribution of on-site operating load rate data), it is determined to be a high load state; If the average value is less than the drop threshold (different values ​​are used for different models, which can be determined by taking the low percentile value of the on-site load rate data distribution), it is judged as a low load state; Apart from the high load and low load states mentioned above, all other states are considered normal.

[0008] This quantification method quantifies the fuzzy load changes into three distinct power demand states, providing a clear decision-making basis for subsequent segmented control.

[0009] 2. First speed-up control strategy (based on high load conditions) When a high load condition is detected and the current engine speed is less than the speed corresponding to the maximum engine torque under the external characteristic curve, the first speed-up control is triggered.

[0010] The rationale behind setting this engine speed condition is that the engine's external characteristic curve has a maximum torque point. When the engine speed is below this point, the engine is in the torque-increasing zone, and increasing the speed can effectively increase the engine's torque reserve, providing sufficient power support for high loads. When the engine speed is above this point, the engine is in the torque-decreasing zone, and continuing to increase the speed not only fails to increase torque output but may also lead to insufficient torque, exacerbating the risk of speed drop or even stalling. Therefore, limiting this speed condition ensures the effectiveness and safety of speed-up control, avoiding ineffective or erroneous speed increases.

[0011] The target speed is determined based on the current speed and current load rate according to a preset functional relationship or mapping table. This control strategy continues to execute until it detects that the current power demand state has changed to a low load state or the current engine speed exceeds the preset exit speed, at which point it exits.

[0012] Regarding the purpose and beneficial effects of setting the preset exit speed: The preset exit speed is set according to the engine's external characteristic curve and is set below the maximum torque point speed (e.g., below the maximum torque point speed by a preset difference). Its purpose is as follows: First, to prevent the engine speed from entering the torque reduction zone—since continuing to increase speed after the maximum torque point will cause the engine output torque to decrease instead of increase, setting the exit speed below the maximum torque point ensures that the engine always operates in the speed range that can output maximum or near maximum torque, preventing a decrease in torque reserve due to entering the torque reduction zone; Second, together with the entry condition of the first speed-up control (current speed less than the maximum torque point speed), it forms a hysteresis control, preventing the speed from frequently entering and exiting speed-up control near the maximum torque point, thus improving system stability; Third, to prevent speed-up control from infinitely increasing the speed, protecting the engine and hydraulic system from overspeed damage.

[0013] The beneficial effects of this setting include: (1) ensuring that the engine always operates in the high torque output range, avoiding insufficient power due to entering the torque drop range; (2) forming a hysteresis loop with the entry condition, suppressing speed oscillation and improving control stability; (3) protecting the engine and hydraulic system, and extending equipment life; (4) allowing different models to independently calibrate the exit speed according to their own external characteristic curves, achieving precise matching. 3. Second acceleration control strategy (based on rapid pressure changes) When a normal or low-load condition is detected, the pressure monitoring process is initiated.

[0014] The term "rapid pressure change" as used in this invention refers to: monitoring the pump port pressure of the hydraulic system at a preset cycle (related to the response speed of the hydraulic pump); if the absolute value of the pressure change exceeds a preset change threshold within a cycle, and the pump port pressure of the hydraulic system exceeds a preset pressure threshold at the end of the cycle, then it is determined to be a rapid pressure change.

[0015] When a sharp change in pressure is detected and the current engine speed is lower than a preset speed threshold, a second acceleration control is triggered. The target speed is determined based on a preset acceleration mapping relationship between the current speed and the current load rate. This mapping relationship ensures that the higher the load rate and the lower the current speed, the larger the increment of the target speed. The technical significance is that a high load rate means the hydraulic system has an urgent power demand on the engine, requiring a rapid increase in torque reserve; a low current speed means the engine is far from its optimal operating range, requiring a significant acceleration to effectively cope with impacts. Through this mapping relationship, the system can dynamically adjust the acceleration amplitude according to the urgency of real-time operating conditions, achieving "on-demand acceleration"—preventing engine stalling due to insufficient acceleration and avoiding fuel waste and mechanical wear caused by excessive acceleration. Those skilled in the art can determine the optimal target speed under different load rate and current speed combinations through a limited number of bench tests, thereby calibrating an acceleration mapping relationship (such as a table or piecewise function) suitable for a specific engine model.

[0016] This control continues until a high-load state is detected in the power demand state. At this point, it automatically switches to the first acceleration control strategy to achieve continuous acceleration after the pressure surge. Acceleration control exits when the power demand state returns to a low-load state.

[0017] 4. Automatic idle speed control If the hydraulic system pump port pressure is lower than the minimum working pressure at idle speed and there is no action for more than the preset idle time, a two-stage speed reduction will be performed: first, the speed will be reduced from the current working speed to high idle speed; if there is still no action, the speed will be reduced from high idle speed to low idle speed.

[0018] When the hydraulic system pump port pressure is detected to be greater than the minimum working pressure at idle speed, smooth start control is executed: the speed is first increased from low idle speed to the secondary target speed, and then smoothly transitioned to the target working speed corresponding to the throttle voltage.

[0019] When a sudden change in hydraulic system pump inlet pressure is detected, and the conditions for sudden changes in pressure and load rate are met, the speed is increased smoothly according to the speed increase control strategy.

[0020] Another aspect of this application provides an excavator engine speed control device, comprising: The load rate acquisition module is used to acquire engine load rate data in real time. The pressure acquisition module is used to acquire and collect pressure data at the pump inlet of the hydraulic system; The status determination module is used to determine the current power demand status as high load, low load or normal based on the data collected by the load rate acquisition module and through time window statistics. The first speed control module is used to calculate the target speed and control the engine speed increase based on the current speed and current load rate when the high load state is determined. The second speed control module is used to monitor the hydraulic system pump port pressure at a preset cycle. When the absolute value of the pressure change exceeds the preset change threshold within a cycle, the hydraulic system pump port pressure exceeds the preset pressure threshold at the end of the cycle, and the current engine speed is less than the preset speed threshold, speed control is triggered. The target speed is determined based on the current speed and the current load rate to perform pressure follow-up compensation, and the module switches to the first speed control module when it is subsequently determined to switch to a high load state. The exit control module is used to exit speed control when the engine is determined to be in a low-load state or the current engine speed exceeds the preset exit speed. The automatic idle speed control module includes: a first deceleration unit for reducing the current operating speed to high idle speed; a second deceleration unit for reducing the high idle speed to low idle speed after a preset time of no action in the high idle speed state; and a smooth start unit for controlling the engine speed to first increase from low idle speed to a secondary target speed and then smoothly transition to the target operating speed corresponding to the throttle voltage when the hydraulic system pump port pressure is detected to be greater than the minimum idle speed operating pressure.

[0021] Compared with the prior art, the present invention has the following beneficial effects: By using a load state quantification method based on time window statistics, the fuzzy load changes are quantified into three distinct power demand states, providing a clear decision basis for segmented control and effectively filtering out instantaneous fluctuations and single-point jump interference.

[0022] A segmented speed-up control architecture with dual trigger conditions is established. The two strategies are automatically switched and interlocked through state values ​​to avoid control logic conflicts and ensure that the control duration matches the actual load requirements.

[0023] The impact prediction mechanism based on the pressure change rate can identify the risk of stalling before the pressure rises sharply but before the speed drops, achieving "pre-intervention" rather than "post-compensation" and effectively solving the problem of stalling caused by pressure shock.

[0024] The closed-loop exit mechanism based on operating conditions determines the exit timing based on the actual load and speed conditions, rather than simply relying on time decay, ensuring that control intervention is precisely matched with actual needs.

[0025] Two-stage automatic idle speed and smooth start control, two-stage deceleration strategy to avoid energy consumption caused by the engine idling at high speed for a long time, and smooth start strategy to avoid speed change problems caused by sudden load changes, taking into account both economy and smoothness.

[0026] By setting the preset exit speed below the engine's maximum torque point speed, hysteresis management of the speed-up control is achieved: on the one hand, it prevents the engine from entering the torque reduction zone, which would cause a decrease in torque; on the other hand, it works in conjunction with the entry conditions to suppress frequent speed jumps, ensuring that the engine always operates in the high torque output range, taking into account power, stability and fuel economy. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0028] Figure 1 This is an overall flowchart of the excavator engine speed control method of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1 This embodiment provides an adaptive segmented speed increase and automatic idle speed control method for excavator engines, applied to the engine control system of excavators in the agricultural and forestry industries. This method uses a controller to collect engine load rate data and hydraulic system pump inlet pressure data from the CAN bus in real time, and then... Figure 1 The process execution control is shown.

[0033] 1. Load factor status determination The controller continuously collects engine load rate data from the CAN bus within a preset time window (1 second in this embodiment, which can be adjusted according to the engine model in actual applications). The average load rate within the window is calculated. The rising and falling thresholds are determined by taking the high and low quantile values ​​respectively after collecting the load rate data distribution under actual operating conditions. In this embodiment, the rising threshold is set to 0.85 and the falling threshold is set to 0.25. In actual applications, these thresholds can be preset or adaptively adjusted according to different engine models and operating conditions.

[0034] The average value is compared with a threshold: when the average value is greater than the rising threshold, the current state is determined to be high load; when the average value is less than the falling threshold, the current state is determined to be low load; otherwise, the state is determined to be normal.

[0035] 2. First acceleration control When a high load condition is detected and the current engine speed is less than the speed corresponding to the maximum torque under the engine external characteristic curve (approximately 1500 rpm in this embodiment), the first acceleration control strategy is triggered.

[0036] The target speed is calculated based on the current speed and current load rate using a calibration function. This function is calibrated using actual engine test data to ensure that the engine can output sufficient torque reserve at a given load rate. Those skilled in the art can determine the minimum target speed required to maintain stable engine operation at different load rates through a limited number of bench tests, thereby establishing a mapping table or fitting function between load rate and target speed.

[0037] The first acceleration control strategy continues to be executed until a low load condition is detected or the current engine speed exceeds the preset exit speed (1450 rpm in this embodiment, which is lower than the maximum torque point speed of 1500 rpm) and then exits.

[0038] 3. Second acceleration control When in normal or low-load condition, the controller monitors the hydraulic system pump port pressure P at a preset period (0.15 seconds in this embodiment, which is related to the pump's response speed) (ADC sampling period 0.01s).

[0039] The pressure change is calculated within each cycle. A rapid pressure change is identified when the following conditions are simultaneously met, triggering the second acceleration control strategy: 1) The absolute value of the pressure change exceeds the preset change threshold (5 MPa in this embodiment); (2) When the cycle ends, the pressure at the pump port of the hydraulic system exceeds the preset pressure threshold (8MPa in this embodiment); (3) The current engine speed is less than the preset speed threshold (1300 rpm in this embodiment). The above values ​​are merely examples of this embodiment. In actual applications, they can be preset or adaptively adjusted based on different machine models and operating conditions.

[0040] Upon triggering, the target speed is calculated based on the current engine speed and load rate according to a pre-calibrated acceleration mapping relationship. The basic logic of this mapping relationship is as follows: assuming the current load rate is L (ranging from 0 to 1) and the current speed is Nc, the difference between the target speed Ns and Nc (i.e., the acceleration increment) increases with increasing L and decreases with increasing Nc. In other words, when the load is heavier and the current speed is lower, the system needs to rapidly and significantly increase the speed to reserve torque; conversely, when the load is lighter or the current speed is already higher, the acceleration increment decreases accordingly. Through this logic, the controller can make an appropriate speed response at the moment of pressure shock, ensuring both power demand and fuel economy. The specific mapping relationship can be implemented using a lookup table method or a piecewise linear function. Bench tests are used to calibrate the optimal target speed under different load rates to ensure the engine accelerates smoothly without stalling under pressure shock.

[0041] This control continues, and if a high-load state is detected during the process, it automatically switches to the first speed-up control strategy until it exits when the load state returns to low.

[0042] 4. Automatic idle speed control When the hydraulic system pump inlet pressure is lower than the minimum idle working pressure (approximately 2 MPa in this embodiment) and no operation is performed for more than a preset idle time (set to 5 seconds in this embodiment), a two-stage speed reduction is executed: First-stage speed reduction: Reduce the current operating speed to high idle speed (approximately 1500 RPM in this embodiment); Second-level speed reduction: If there is still no action for a preset time (10 seconds in this embodiment), the speed will be reduced from high idle speed to low idle speed (approximately 1000 RPM in this embodiment).

[0043] When the hydraulic system pump port pressure is detected to be greater than the minimum working pressure at idle speed, smooth start control is executed: the engine speed is first increased from low idle speed to the sub-target speed (approximately 1300 rpm in this embodiment), and then smoothly transitioned to the target working speed corresponding to the throttle voltage.

[0044] When a sudden change in hydraulic system pump inlet pressure is detected, and the conditions for sudden changes in pressure and load rate are met, the speed is increased smoothly according to the above-mentioned speed control strategy.

[0045] Example 2 This embodiment provides an excavator engine speed control device, including: The load rate acquisition module is used to acquire engine load rate data in real time via the CAN bus; The pressure acquisition module is used to acquire hydraulic system pump port pressure data in real time through ADC sampling. The status determination module is used to collect engine load rate data in a preset time window, calculate the average load rate within the window, and compare it with the rising threshold and falling threshold to determine the power demand status as high load state, low load state or normal state. The first speed control module is used to calculate the target speed and control the engine speed increase when the engine is determined to be in a high load state and the current speed is less than the speed corresponding to the maximum torque under the external characteristic curve. The second speed control module is used to monitor the hydraulic system pump port pressure at a preset cycle. When the absolute value of the pressure change exceeds the preset change threshold within a cycle, the hydraulic system pump port pressure exceeds the preset pressure threshold at the end of the cycle, and the current engine speed is less than the preset speed threshold, speed control is triggered. The target speed is determined based on the current speed and the current load rate to perform pressure follow-up compensation, and the module switches to the first speed control module when it is subsequently determined to switch to a high load state. The exit control module is used to exit speed control when the system is determined to be in a low-load state or when the current speed exceeds the preset exit speed. The automatic idle speed control module includes a first speed reduction unit for reducing the current operating speed to high idle speed; a second speed reduction unit for reducing the speed from high idle speed to low idle speed after a preset time if there is no action at high idle speed; and a smooth start unit for controlling the engine speed to increase from low idle speed to the secondary target speed and then smoothly transition to the target operating speed corresponding to the throttle voltage when the hydraulic system pump port pressure is detected to be greater than the minimum working pressure at idle speed.

[0046] The above modules can be integrated into the main controller of the excavator and implemented through software programs, or they can be implemented through independent hardware circuits.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling the engine speed of an excavator, characterized in that, Includes the following steps: (1) Real-time acquisition of engine load rate data and hydraulic system pump inlet pressure data; (2) Perform time window statistics on load factor data, and quantify the current power demand status as high load status, low load status or normal status based on the statistical results; (3) When the condition is determined to be high load, the first speed-up control strategy is executed, the target speed is calculated based on the current speed and the current load rate, and the engine speed is controlled to increase; (4) When it is determined to be a non-high load state, monitor the change of hydraulic system pump port pressure. If a sharp change in pressure is detected and the current engine speed is lower than the preset speed threshold, the second speed control strategy is triggered. The target speed is calculated based on the current speed and the current load rate to perform pressure follow-up compensation. When it is subsequently determined to be a high load state, switch to the first speed control strategy. (5) When the engine is determined to be in a low load state or the current engine speed exceeds the preset exit speed, the speed increase control is exited; (6) When the pressure at the pump port of the hydraulic system is less than the minimum working pressure at idle speed and there is no action for more than a preset time, a two-stage speed reduction automatic idle speed control strategy is executed.

2. The excavator engine speed control method according to claim 1, characterized in that, In step (2), the time window statistics are specifically as follows: engine load rate data are collected in a preset time window, the average load rate within the window is calculated, and when the average value is greater than a preset rising threshold, it is determined to be a high load state; when the average value is less than a preset falling threshold, it is determined to be a low load state; otherwise, it is determined to be a normal state.

3. The excavator engine speed control method according to claim 2, characterized in that, The rising threshold and falling threshold are preset or adaptively adjusted based on the quantile values ​​of the distribution of the on-site working condition load rate data.

4. The excavator engine speed control method according to claim 1, characterized in that, In step (3), the triggering condition of the first speed control strategy also includes: the current engine speed is less than the speed corresponding to the maximum torque under the engine external characteristic curve.

5. The excavator engine speed control method according to claim 1, characterized in that, In step (4), the rapid pressure change refers to: monitoring the hydraulic system pump port pressure at a preset cycle, the absolute value of the pressure change within one cycle exceeding a preset change threshold, and the hydraulic system pump port pressure exceeding a preset pressure threshold at the end of the cycle.

6. The excavator engine speed control method according to claim 1, characterized in that, The target speed in the second speed-up control is determined according to the current engine speed and the current load rate, based on a preset speed-up mapping relationship. The speed-up mapping relationship ensures that the higher the current load rate and the lower the current speed, the greater the increment of the target speed.

7. The excavator engine speed control method according to claim 1, characterized in that, In step (5), the preset exit speed is set according to the engine external characteristic curve.

8. The excavator engine speed control method according to claim 1, characterized in that, In step (6), the two-stage automatic idling control includes: first, reducing the current operating speed to high idling speed; if there is still no action for a preset time, then reducing the speed from high idling speed to low idling speed.

9. The excavator engine speed control method according to claim 8, characterized in that, When the hydraulic system pump port pressure is detected to be greater than the minimum working pressure at idle speed, smooth start control is executed. The engine speed is first increased from low idle speed to the secondary target speed, and then smoothly transitioned to the target working speed corresponding to the throttle voltage.

10. A speed control device for an excavator engine, characterized in that, include: The load rate acquisition module is used to acquire engine load rate data in real time. The pressure acquisition module is used to acquire and collect pressure data at the pump inlet of the hydraulic system; The status determination module is used to determine the current power demand status as high load, low load or normal based on the data collected by the load rate acquisition module and through time window statistics. The first speed control module is used to calculate the target speed and control the engine speed increase based on the current speed and current load rate when the high load state is determined. The second speed control module is used to monitor the hydraulic system pump port pressure at a preset cycle. When the absolute value of the pressure change exceeds the preset change threshold within a cycle, the hydraulic system pump port pressure exceeds the preset pressure threshold at the end of the cycle, and the current engine speed is less than the preset speed threshold, speed control is triggered. The target speed is determined based on the current speed and the current load rate to perform pressure follow-up compensation, and the module switches to the first speed control module when it is subsequently determined to switch to a high load state. The exit control module is used to exit speed control when the engine is determined to be in a low-load state or the current engine speed exceeds the preset exit speed. The automatic idle speed control module includes: a first deceleration unit for reducing the current operating speed to high idle speed; a second deceleration unit for reducing the high idle speed to low idle speed after a preset time of no action in the high idle speed state; and a smooth start unit for controlling the engine speed to first increase from low idle speed to a secondary target speed and then smoothly transition to the target operating speed corresponding to the throttle voltage when the hydraulic system pump port pressure is detected to be greater than the minimum idle speed operating pressure.

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