Load-based main pump control method and excavator

Abstract

The invention discloses a load-based main pump control method and an excavator, and belongs to the technical field of excavator control. The method comprises the steps that the real-time pressure value of the excavator main pump and the pressure value of the excavator main pump in the last statistical period are obtained; according to the pressure value of the main pump of the excavator in the previous statistical period, the step length of the current statistical period is determined; according to the real-time pressure value of the main pump of the excavator and the step length of the current statistical period, the real-time pressure gradient change rate in the current statistical period is calculated; according to the real-time pressure value and the real-time pressure gradient change rate of the excavator main pump, the real-time pressure cut-off amplitude in the current statistical period is determined; and according to the real-time pressure cutting amplitude in the current statistical period, the real-time current of the main pump of the excavator is adjusted to control the opening degree of the main pump. The opening degree of the main pump of the excavator can be adjusted in a self-adaptive mode according to different working conditions, and energy loss is reduced.

Description

Technical Field

[0001] The present invention relates to a load-based main pump control method and an excavator, belonging to the technical field of excavator control. Background Art

[0002] When an excavator is operating, after the main pump pressure rises, a fixed-amplitude pressure cut-off mode is usually adopted to directly reduce the main pump current, and all excavators adopt the same control strategy.

[0003] However, the loads faced by different excavators under different working conditions are not the same. Even when constructing in the same area, as the excavation depth changes during the construction operation, the load of the excavator will also change to a certain extent. The existing control strategy, which adopts a fixed-amplitude pressure cut-off mode, does not have the adaptability to working condition changes. When the load of the excavator is large, the pressure cut-off is not sufficient, resulting in hydraulic overflow loss and thus high fuel consumption of the whole machine. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a load-based main pump control method and an excavator, which can adaptively adjust the main pump opening of the excavator according to different working conditions to reduce energy loss. To achieve the above purpose, the present invention is implemented by the following technical solutions: In the first aspect, the present invention provides a load-based main pump control method, including: Obtaining the real-time pressure value of the main pump of the excavator and the pressure value of the main pump of the excavator in the previous statistical period; Confirming the step length of the current statistical period according to the pressure value of the main pump of the excavator in the previous statistical period; Calculating the real-time pressure gradient change rate in the current statistical period according to the real-time pressure value of the main pump of the excavator and the step length of the current statistical period; Determining the real-time pressure cut-off amplitude in the current statistical period according to the real-time pressure value of the main pump of the excavator and the real-time pressure gradient change rate; Adjusting the real-time current of the main pump of the excavator to control the main pump opening according to the real-time pressure cut-off amplitude in the current statistical period.

[0005] Combined with the first aspect, optionally, the step of confirming the step length of the current statistical period according to the pressure value of the main pump of the excavator in the previous statistical period includes: Selecting the time point when the pressure value is the largest and the time point when the pressure value is the smallest from the pressure values of the main pump of the excavator in the previous statistical period; Taking the duration from the time point when the pressure value is the largest to the time point when the pressure value is the smallest as the step length of the current statistical period; Among them, when the pressure value at the time of the maximum pressure value in the previous statistical period is less than the main pump overflow pressure, the pressure value of the main pump of the excavator in the previous statistical period is invalid data, and the step size of the current statistical period is confirmed based on the pressure value of the main pump of the excavator in the previous statistical period with invalid data.

[0006] Combined with the first aspect, optionally, according to the real-time pressure value of the main pump of the excavator and the step size of the current statistical period, calculate the real-time pressure gradient change rate in the current statistical period, including: In the time interval from the starting sampling time point to the real-time sampling time point of the current statistical period, select the maximum pressure value Pmax and the minimum pressure value Pmin; The real-time pressure gradient change rate kt is calculated and expressed by the following formula: kt = (Pmax - Pmin) / t, where, t represents the duration of the time interval from the starting sampling time point to the real-time sampling time point of the current statistical period, and t is less than or equal to the step size of the current statistical period.

[0007] Combined with the first aspect, optionally, the determining the real-time pressure cut-off amplitude in the current statistical period according to the real-time pressure value and the real-time pressure gradient change rate of the main pump of the excavator includes: Obtain the pressure cut-off amplitude corresponding to the pressure value of the main pump of the excavator in the previous statistical period as the initial value of the pressure cut-off amplitude in the current statistical period; Initialize the pressure threshold interval; In response to the real-time pressure value of the main pump of the excavator being within the pressure threshold interval, determine whether the real-time pressure gradient change rate exceeds the preset change threshold; If it exceeds, calculate the amplitude of the real-time pressure gradient change rate exceeding the preset change threshold, and use the calculated amplitude to correct the initial value of the pressure cut-off amplitude to obtain the real-time pressure cut-off amplitude; If it does not exceed, use the preset safety adjustment coefficient to correct the initial value of the pressure cut-off amplitude to obtain the real-time pressure cut-off amplitude.

[0008] Combined with the first aspect, optionally, the minimum value of the pressure threshold interval is the constant power pump pressure setting value of the excavator, and the maximum value of the pressure threshold interval is the average value of the maximum pressure values of multiple statistical periods in the database.

[0009] Combined with the first aspect, optionally, in response to the real-time pressure value of the main pump of the excavator not reaching the constant power pump pressure setting value of the excavator, output the initial value of the pressure cut-off amplitude in the current statistical period as the real-time pressure cut-off amplitude.

[0010] In combination with the first aspect, optionally, in response to the real-time pressure value of the excavator main pump exceeding the maximum value of the pressure threshold range, the maximum value of the pressure cut-off amplitude is the real-time pressure cut-off amplitude; when the real-time pressure value of the excavator main pump decreases and is within the pressure threshold range, it is determined whether the real-time pressure gradient change rate exceeds a preset change threshold.

[0011] In combination with the first aspect, optionally, the database is updated through the following steps: When the pressure value of the excavator main pump reaches the excavator constant power pump pressure setting value, record data is started, and the record data includes a record statistical period, a sampling time point, and a pressure value; The sliding window mechanism is used to retain the data of the most recent N statistical periods and eliminate the old data outside the window range.

[0012] In combination with the first aspect, optionally, when the duration for which the real-time pressure gradient change rate exceeds the preset change threshold reaches the preset time threshold, the maximum value of the pressure cut-off amplitude is the real-time pressure cut-off amplitude until the real-time pressure value of the excavator main pump decreases and is within the pressure threshold range.

[0013] In a second aspect, the present invention provides an excavator, which uses a main pump control method based on load described in the first aspect to adjust the real-time current of the excavator main pump for main pump opening control.

[0014] Compared with the prior art, the beneficial effects achieved by the main pump control method and excavator based on load provided by the embodiments of the present invention include: The present invention obtains the real-time pressure value of the excavator main pump and the pressure value of the excavator main pump in the previous statistical period; based on the pressure value of the excavator main pump in the previous statistical period, the step size of the current statistical period is confirmed; based on the real-time pressure value of the excavator main pump and the step size of the current statistical period, the real-time pressure gradient change rate in the current statistical period is calculated; by calculating the real-time pressure gradient change rate, the present invention can quickly identify the load mutation in the current statistical period; Based on the real-time pressure value and the real-time pressure gradient change rate of the excavator main pump, the present invention determines the real-time pressure cut-off amplitude in the current statistical period; the present invention can achieve precise adaptive control for different working conditions, avoid the overflow loss caused by the traditional fixed amplitude pressure cut-off mode, and significantly reduce the overall energy consumption of the machine; Based on the real-time pressure cut-off amplitude in the current statistical period, the present invention adjusts the real-time current of the excavator main pump for main pump opening control; the present invention can adaptively adjust the opening of the excavator main pump under different working conditions, can effectively reduce hydraulic overflow loss and fuel consumption, reduce carbon emissions, conform to the industry development trend of green manufacturing and energy conservation and consumption reduction, reduce the user's operation cost, and achieve reduction of energy loss. Description of the Drawings

[0015] Figure 1 It is a flow chart of a load-based main pump control method in Example 1 of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0017] Example 1

[0018] like Figure 1 As shown, this embodiment provides a load-based main pump control method, including: Obtain the real-time pressure value of the excavator main pump and the pressure value of the excavator main pump in the previous statistical period; According to the pressure value of the excavator main pump in the previous statistical period, determine the step length of the current statistical period; According to the real-time pressure value of the main pump of the excavator and the step length of the current statistical period, the real-time pressure gradient change rate within the current statistical period is calculated; According to the real-time pressure value and real-time pressure gradient change rate of the excavator main pump, determine the real-time pressure cut-off amplitude within the current statistical period; According to the real-time pressure cut-off amplitude in the current statistical period, the real-time current of the excavator main pump is adjusted to control the main pump opening.

[0019] The specific steps include: Step 1: Obtain the real-time pressure value of the excavator main pump and the pressure value of the excavator main pump in the previous statistical period.

[0020] When the maximum pressure value of the excavator main pump in the previous statistical period is less than the main pump overflow pressure, the pressure value of the excavator main pump in the previous statistical period is invalid data. The pressure value of the excavator main pump in the previous statistical period of the statistical period where the invalid data is located is obtained again.

[0021] Before obtaining the real-time pressure value of the excavator main pump for the first time, a pressure test of the excavator main pump is performed according to an existing test procedure to obtain an initial database.

[0022] This embodiment also includes updating the database: when the pressure value of the excavator main pump reaches the excavator constant power pump pressure setting value, start recording data (the recorded data includes the recording statistical period, sampling time point and pressure value); use a sliding window mechanism to retain the data of the most recent N statistical periods, and remove old data that exceeds the window range; and filter invalid data deviations through the eigenvalue method.

[0023] Step 2: Determine the step length of the current statistical period based on the pressure value of the excavator main pump in the previous statistical period.

[0024] Step 2.1: Select the time point with the maximum pressure value and the time point with the minimum pressure value from the pressure values of the main pump of the excavator in the previous statistical period.

[0025] Step 2.2: Take the duration from the time point with the maximum pressure value to the time point with the minimum pressure value as the step length of the current statistical period.

[0026] When the pressure value of the main pump of the excavator in the previous statistical period is invalid data, based on the pressure value of the main pump of the excavator in the previous statistical period of the statistical period where the invalid data is obtained again, confirm the step length of the current statistical period.

[0027] If the current statistical period is the first statistical period, based on the duration between the time point with the maximum pressure value and the time point with the minimum pressure value in the initial database, confirm the step length of the current statistical period.

[0028] In this embodiment, by dynamically adjusting the step length of the statistical period, it is possible to ensure that the data statistical period is synchronized with the actual load change. For example, in heavy load conditions, the pressure changes violently, shortening the step length of the data statistical period to quickly capture the transient pressure peak and improve the response speed. For example, in light load conditions, the pressure fluctuation is gentle, extending the step length of the data statistical period to reduce redundant calculations.

[0029] In this embodiment, by dynamically adjusting the step length of the statistical period, it is possible to avoid the noise that may be introduced by a fixed statistical period, such as short-term pressure fluctuations, and ensure that the subsequent results truly reflect the load state.

[0030] Step 3: Calculate the real-time pressure gradient change rate within the current statistical period according to the real-time pressure value of the main pump of the excavator and the step length of the current statistical period.

[0031] Step 3.1: Select the maximum pressure value Pmax and the minimum pressure value Pmin within the time interval from the starting sampling time point to the real-time sampling time point of the current statistical period.

[0032] Step 3.2: Calculate the real-time pressure gradient change rate kt, which is expressed by the following formula: kt = (Pmax - Pmin) / t, where t represents the duration of the time interval from the starting sampling time point to the real-time sampling time point of the current statistical period, and t is less than or equal to the step length of the current statistical period.

[0033] The real-time pressure gradient change rate is divided into a positive pressure gradient change rate and a negative pressure gradient change rate, which are determined by the pressure values at the starting sampling time point and the ending time point of the current statistical period.

[0034] Specifically, if the pressure value collected at the starting sampling time point of the current statistical period is less than the pressure value collected at the ending sampling time point, it indicates that the main pump pressure increases from the starting sampling time point to the ending sampling time point, and the real-time pressure gradient change rate is the positive real-time pressure gradient change rate. If the pressure value collected at the starting sampling time point of the current statistical period is greater than the pressure value collected at the ending sampling time point, it indicates that the main pump pressure decreases from the starting sampling time point to the ending sampling time point, and the real-time pressure gradient change rate is the negative real-time pressure gradient change rate.

[0035] It should be noted that although a new real-time pressure gradient change rate may be calculated at each moment within the statistical period, the positive and negative directions are always determined based on the pressure values at the starting sampling time point and the ending sampling time point of the statistical period.

[0036] In this embodiment, by calculating the real-time pressure gradient change rate, the load mutation within the current statistical period can be quickly identified.

[0037] Step 4: Determine the real-time pressure cut-off amplitude within the current statistical period according to the real-time pressure value and the real-time pressure gradient change rate of the excavator main pump; Step 4.1: Obtain the pressure cut-off amplitude corresponding to the pressure value of the excavator main pump in the previous statistical period as the initial value of the pressure cut-off amplitude for the current statistical period.

[0038] Step 4.2: Initialize the pressure threshold range.

[0039] The minimum value of the pressure threshold range is the set value of the constant power pump pressure of the excavator.

[0040] The maximum value of the pressure threshold range is the average value of the maximum pressure values in multiple statistical periods in the database.

[0041] Step 4.3: In response to the real-time pressure value of the excavator main pump being within the pressure threshold range, determine whether the real-time pressure gradient change rate exceeds the preset change threshold.

[0042] Specifically, if the real-time pressure value of the excavator main pump does not reach the set value of the constant power pump pressure of the excavator, output the initial value of the pressure cut-off amplitude for the current statistical period as the real-time pressure cut-off amplitude.

[0043] Specifically, if the real-time pressure value of the excavator main pump exceeds the maximum value of the pressure threshold range, output the maximum value of the pressure cut-off amplitude as the real-time pressure cut-off amplitude. Until the real-time pressure value of the excavator main pump decreases and is within the pressure threshold range, re-judge whether the real-time pressure gradient change rate exceeds the preset change threshold in Step 4.3.

[0044] Step 4.4: If it exceeds, calculate the amplitude of the real-time pressure gradient change rate exceeding the preset change threshold, and use the calculated amplitude to correct the initial value of the pressure cut-off amplitude to obtain the real-time pressure cut-off amplitude; if it does not exceed, use the preset safety adjustment coefficient to correct the initial value of the pressure cut-off amplitude to obtain the real-time pressure cut-off amplitude.

[0045] When the duration of the real-time pressure gradient change rate exceeding the preset change threshold reaches the preset time threshold, the maximum value of the pressure cut-off amplitude is output as the real-time pressure cut-off amplitude until the real-time pressure value of the main pump of the excavator decreases and is within the pressure threshold range.

[0046] For example, the initial value of the pressure cut-off amplitude (the initial value of the pressure cut-off amplitude is the initial amplitude) is "the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 mA". The value of the real-time pressure gradient change rate is 0.8, which exceeds the preset change threshold of 0.5, and the duration is 2 statistical cycles, not reaching the preset time threshold. Calculate the amplitude of the real-time pressure gradient change rate exceeding the preset change threshold (0.8 - 0.5) / 0.5 = 0.6, and use the calculated amplitude of 0.6 to correct the initial value of the pressure cut-off amplitude. If it is a positive pressure gradient change rate, the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 + 50×0.6 = 80 mA. If it is a negative pressure gradient change rate, the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 - 50×0.6 = 20 mA.

[0047] For example, the initial value of the pressure cut-off amplitude is "the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 mA". The value of the real-time pressure gradient change rate is 0.2, which does not exceed the preset change threshold of 0.5, and use the preset safety adjustment coefficient t = 0.1 to correct the initial value of the pressure cut-off amplitude. If it is a positive pressure gradient change rate, the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 + 50×0.1 = 55 mA. If it is a negative pressure gradient change rate, the main pump pressure starts to cut off at 300 bar, the current starts to decrease, and for every 10 bar increase in pressure, the current decreases by 50 - 50×0.1 = 45 mA.

[0048] In this embodiment, determining the real-time pressure cut-off amplitude within the current statistical cycle according to the real-time pressure value and the real-time pressure gradient change rate of the main pump of the excavator can achieve precise adaptive control for different working conditions, avoid the overflow loss caused by the traditional fixed-amplitude pressure cut-off mode, and significantly reduce the overall energy consumption of the machine.

[0049] In this embodiment, the dynamic step size combined with the real-time pressure gradient calculation can accurately judge the pressure cut-off amplitude, avoiding the waste of overflow energy caused by "insufficient cut-off" or "excessive cut-off" under the traditional fixed step size.

[0050] Step 5: Adjust the real-time current of the main pump of the excavator according to the real-time pressure cut-off amplitude within the current statistical period to control the opening of the main pump.

[0051] This embodiment can adaptively adjust the opening of the main pump of the excavator according to different working conditions, effectively reducing hydraulic overflow loss and fuel consumption, reducing carbon emissions, conforming to the industry development trend of green manufacturing and energy conservation and consumption reduction, reducing the user's operation cost, and achieving the reduction of energy loss.

[0052] Embodiment 2

[0053] This embodiment provides an excavator, which adjusts the real-time current of the main pump of the excavator by using the load-based main pump control method provided in Embodiment 1 to control the opening of the main pump.

[0054] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A load-based main pump control method, characterized in that: include: Obtain the real-time pressure value of the excavator main pump and the pressure value of the excavator main pump in the previous statistical period; According to the pressure value of the main pump of the excavator in the previous statistical period, the step length of the current statistical period is determined; According to the real-time pressure value of the main pump of the excavator and the step length of the current statistical period, the real-time pressure gradient change rate within the current statistical period is calculated; According to the real-time pressure value and real-time pressure gradient change rate of the excavator main pump, determine the real-time pressure cut-off amplitude within the current statistical period; According to the real-time pressure cut-off amplitude in the current statistical period, the real-time current of the excavator main pump is adjusted to control the main pump opening.

2. The load-based main pump control method according to claim 1, characterized in that: Determining the step length of the current statistical cycle according to the pressure value of the main pump of the excavator in the previous statistical cycle includes: Select the time point when the pressure value is the maximum and the time point when the pressure value is the minimum from the pressure values ​​of the main pump of the excavator in the previous statistical period; The time from the time point when the pressure value is the maximum to the time point when the pressure value is the minimum is used as the step length of the current statistical period; Among them, when the pressure value when the pressure value is the largest in the previous statistical period is less than the overflow pressure of the main pump, the pressure value of the excavator main pump in the previous statistical period is invalid data. The pressure value of the excavator main pump in the previous statistical period based on the invalid data confirms the step length of the previous statistical period.

3. The load-based main pump control method according to claim 1, characterized in that: According to the real-time pressure value of the excavator main pump and the step length of the current statistical period, the real-time pressure gradient change rate within the current statistical period is calculated, including: In the time interval from the start sampling time point of the current statistical period to the real-time sampling time point, select the maximum pressure value Pmax and the minimum pressure value Pmin; Calculate the real-time pressure gradient change rate k t It is expressed by the following formula: k t =(Pmax-Pmin) / t, Wherein, t represents the duration of the time interval from the start sampling time point of the current statistical period to the real-time sampling time point, and t is less than or equal to the step length of the current statistical period.

4. The load-based main pump control method according to claim 1, characterized in that: Determining the real-time pressure cut-off amplitude within the current statistical period according to the real-time pressure value and the real-time pressure gradient change rate of the excavator main pump includes: Obtain the pressure cut-off amplitude corresponding to the pressure value of the main pump of the excavator in the previous statistical period as the initial value of the pressure cut-off amplitude in the current statistical period; Initialize the pressure threshold interval; In response to the real-time pressure value of the main pump of the excavator being within the pressure threshold interval, determining whether the real-time pressure gradient change rate exceeds a preset change threshold; If it exceeds, the amplitude of the real-time pressure gradient change rate exceeding the preset change threshold is calculated, and the calculated amplitude is used to correct the initial value of the pressure cut-off amplitude to obtain the real-time pressure cut-off amplitude; If it does not exceed, the initial value of the pressure cut-off amplitude is corrected using the preset safety adjustment factor to obtain the real-time pressure cut-off amplitude.

5. The load-based main pump control method according to claim 4, characterized in that: The minimum value of the pressure threshold interval is the constant power pump pressure setting value of the excavator, and the maximum value of the pressure threshold interval is the average of the maximum values ​​of the pressure values ​​of multiple statistical periods in the database.

6. The load-based main pump control method according to claim 4, characterized in that: In response to the real-time pressure value of the excavator main pump not reaching the excavator constant power pump pressure setting value, the initial value of the pressure cut-off amplitude of the current statistical period is output as the real-time pressure cut-off amplitude.

7. The load-based main pump control method according to claim 4, characterized in that: In response to the real-time pressure value of the excavator main pump exceeding the maximum value of the pressure threshold interval, the maximum value of the output pressure cut-off amplitude is the real-time pressure cut-off amplitude; when the real-time pressure value of the excavator main pump decreases and is within the pressure threshold interval, a judgment is made as to whether the real-time pressure gradient change rate exceeds the preset change threshold.

8. The load-based main pump control method according to claim 5, characterized in that: The database is updated by the following steps: When the pressure value of the main pump of the excavator reaches the set value of the constant power pump pressure of the excavator, the data recording is started, and the recorded data includes the recording statistical period, the sampling time point and the pressure value; A sliding window mechanism is used to retain the data of the most recent N statistical periods and remove old data that exceeds the window range.

9. The load-based main pump control method according to claim 4, characterized in that: When the real-time pressure gradient change rate exceeds the preset change threshold for a duration that reaches a preset time threshold, the maximum value of the output pressure cut-off amplitude is the real-time pressure cut-off amplitude until the real-time pressure value of the excavator main pump decreases and is within the pressure threshold range.

10. An excavator, characterized in that: A load-based main pump control method as described in any one of claims 1 to 9 is used to adjust the real-time current of the excavator main pump to control the main pump opening.

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