Control method and system of positive flow system hydraulic excavator

Abstract

The invention provides a control method and system for a positive flow system hydraulic excavator, and belongs to the technical field of excavator control. The method comprises the steps that engine instantaneous operation parameters, main pump pressure and pilot handle pressure are obtained; calculating the instantaneous limit power of the engine according to the instantaneous operation parameters of the engine; calculating the instantaneous required power of the main pump according to the main pump pressure and the pilot handle pressure; and controlling the output power of the main pump according to the instantaneous limit power of the engine and the instantaneous demand power of the main pump. The actual output power of the main pump is obtained by comparing the instantaneous limited power of the engine with the instantaneous required power of the main pump all the time, accurate matching of the output power of the hydraulic system and the power of the engine is achieved, more excellent oil consumption efficiency characteristics are brought, and the performance of the excavator is greatly improved.

Description

Technical Field

[0001] The invention relates to a control method and system for a positive flow system hydraulic excavator, belonging to the technical field of excavator control. Background Art

[0002] my country's construction machinery industry has developed by leaps and bounds, among which excavators play an indispensable role and occupy a major position. Due to the national requirements for environmental protection and energy conservation and consumption reduction, higher requirements are currently placed on the smoke density, fuel consumption, efficiency, and operability of hydraulic excavators. For positive flow system hydraulic excavators, whether the engine and pump are matched reasonably determines the excavator's fuel consumption, efficiency, and smoke density.

[0003] Traditional control methods cannot perfectly match the relationship between the torque provided by the engine and the torque required by the pump. In excavation conditions, when the initial torque required by the pump is greater than the initial torque that the engine can provide, it will cause negative effects such as engine speed drop and high smoke density. There are two types of power limits in existing positive flow systems. One is the power gradient loading limit disclosed in CN110644564A; the other is the power limit based on the maximum available torque of the engine disclosed in CN110984282A.

[0004] However, the power gradient loading method sets a maximum hydraulic system power for a certain gear and limits the maximum power of the hydraulic system to not exceed this limited power. At the same time, the hydraulic power is loaded with a fixed slope, which cannot accurately control the hydraulic system power loading process. During the loading process, if the hydraulic system power is loaded too quickly, it is easy to exceed the engine power supply capacity, bringing adverse effects. If the loading is too slow, the vehicle efficiency will be insufficient. In the power limitation method based on the maximum available torque of the engine, the maximum available torque of the engine can accurately reflect the instantaneous power supply capacity of the engine. The hydraulic system power is limited based on this, which can ensure the maximum utilization efficiency of the engine power. However, this parameter is not accurately provided by all brands of engines, so it is difficult to promote.

[0005] In summary, a better power limitation control strategy is needed to ensure that the torque provided by the engine is approximately matched to the pump load torque. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a control method and system for a positive flow system hydraulic excavator, which solves the problem that the torque provided by the engine cannot be perfectly matched with the torque required by the pump.

[0007] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0008] In a first aspect, the present invention provides a control method for a hydraulic excavator with a positive flow system, comprising: acquiring instantaneous operating parameters of the engine, main pump pressure and pilot handle pressure; calculating the instantaneous limiting power of the engine according to the instantaneous operating parameters of the engine; calculating the instantaneous required power of the main pump according to the main pump pressure and the pilot handle pressure; in response to the instantaneous required power of the main pump being not greater than the instantaneous limited power of the engine, controlling the main pump output power to be equal to the instantaneous required power of the main pump; in response to the instantaneous required power of the main pump being greater than the instantaneous limited power of the engine, controlling the main pump output power to be equal to the instantaneous limited power of the engine.

[0009] Further, the calculation of the instantaneous required power of the main pump according to the main pump pressure and the pilot handle pressure includes:

[0010] The main pump pressure is subjected to second-order filtering to obtain the main pump instantaneous pressure;

[0011] According to the pilot handle pressure, the effective stroke of the pilot handle is calibrated to obtain the instantaneous required displacement of the main pump;

[0012] The instantaneous required power of the main pump is calculated according to the instantaneous pressure of the main pump and the instantaneous required displacement of the main pump.

[0013] Furthermore, it also includes: in response to the instantaneous required power of the main pump being not greater than the instantaneous limited power of the engine, controlling the output displacement of the main pump to be equal to the instantaneous required displacement of the main pump;

[0014] In response to the instantaneous required power of the main pump being greater than the instantaneous limited power of the engine, the corresponding main pump output displacement is calculated according to the instantaneous limited power of the engine.

[0015] Furthermore, it also includes: converting the output displacement of the main pump into the output current of the solenoid valve according to a preset displacement-current relationship curve.

[0016] Furthermore, the instantaneous operating parameters of the engine include: intake pressure parameters, engine speed, torque percentage and instantaneous fuel consumption.

[0017] Furthermore, the main pump includes a first main pump and a second main pump; the calculation formula for the instantaneous required power of the main pump is:

[0018] ;

[0019] In the formula, is the instantaneous pressure of the first main pump, is the instantaneous required displacement of the first main pump, is the instantaneous pressure of the second main pump, is the instantaneous required displacement of the second main pump, is the engine speed.

[0020] Furthermore, the calculation of the corresponding main pump output displacement according to the instantaneous limited power of the engine includes:

[0021] ;

[0022] ;

[0023] In the formula, is the output displacement of the first main pump, is the output displacement of the second main pump, is the output power of the first main pump, is the output power of the second main pump, and equal.

[0024] In a second aspect, the present invention provides a control system for a positive flow system hydraulic excavator, the control system being used to implement the control method for the positive flow system hydraulic excavator as described in the first aspect; the control system comprising: a controller, an instantaneous operating parameter acquisition unit and a pressure acquisition unit; the instantaneous operating parameter acquisition unit and the pressure acquisition unit are respectively communicatively connected to the controller; the controller is used to calculate the instantaneous limiting power of the engine according to the instantaneous operating parameters of the engine acquired by the instantaneous operating parameter acquisition unit, calculate the instantaneous required power of the main pump according to the pressure data acquired by the pressure acquisition unit, and control the output power of the main pump according to the magnitude of the instantaneous limiting power of the engine and the instantaneous required power of the main pump.

[0025] Furthermore, the controller is also used to: control the main pump output displacement according to the instantaneous limited power of the engine and the instantaneous required power of the main pump, and convert the main pump output displacement into the solenoid valve output current according to a preset displacement-current relationship curve.

[0026] Furthermore, the pressure acquisition unit includes: a first pressure sensor for acquiring a pressure value of the main pump and a second pressure sensor for acquiring a pressure value of the pilot handle.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) In the present invention, when the controller starts working, the instantaneous operating parameters of the engine are used to calculate the current maximum available power of the engine as the instantaneous limit power of the engine, and the output power of the main pump is limited by this. At the same time, the instantaneous required power of the main pump is calculated according to the main pump pressure and the pilot handle pressure. The instantaneous limit power of the engine and the instantaneous required power of the main pump are both instantaneous values. It is necessary to compare the two values ​​to obtain the actual output power of the main pump. This method realizes the precise matching of the output power of the hydraulic system and the engine power, brings better fuel consumption efficiency characteristics, and greatly improves the performance of the excavator;

[0029] (2) The two parameters used in the present invention, namely the engine intake pressure signal and the engine instantaneous fuel consumption, are directly collected by the engine sensor. All engines can acquire these two parameters. The method of calculating the instantaneous maximum available power of the engine using these two parameters is applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of the control method of the positive flow system hydraulic excavator provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The terms "first", "second", "third", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than the content illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0032] Example 1

[0033] The present invention provides a control method for a positive flow system hydraulic excavator, such as Figure 1 As shown, including:

[0034] Step 1: Obtain the instantaneous operating parameters of the engine, main pump pressure and pilot handle pressure.

[0035] In a specific embodiment, the instantaneous operating parameters of the engine include: intake pressure parameters, engine speed, torque percentage and instantaneous fuel consumption.

[0036] In a more specific embodiment, the instantaneous operating parameters of the engine are collected by the instantaneous operating parameter collection unit and stored in the engine ECU, and the engine ECU and the controller are connected by CAN bus communication. The engine ECU processes and modulates the instantaneous operating parameters of the engine according to the J1939 protocol, and then sends them to the controller. After receiving the data, the controller decodes the received data according to the J1939 protocol.

[0037] Step 2: Calculate the instantaneous limited power of the engine according to the instantaneous operating parameters of the engine.

[0038] The current maximum available power of the engine is calculated based on the actual instantaneous operating parameters of the engine, and is used as the maximum limiting power to limit the actual output power of the main pump of the hydraulic system.

[0039] Step 3: Calculate the instantaneous required power of the main pump according to the main pump pressure and the pilot handle pressure.

[0040] Specifically, the instantaneous pressure of the main pump and the instantaneous required displacement of the main pump are obtained according to the collected main pump pressure and the pilot handle pressure, and then the instantaneous required power of the main pump is calculated according to the instantaneous pressure of the main pump and the instantaneous required displacement of the main pump.

[0041] In a specific embodiment, the instantaneous pressure of the main pump is obtained by subjecting the main pump pressure to a second-order filtering process; and the instantaneous required displacement of the main pump is obtained by introducing a calibration of the effective stroke of the pilot handle according to the pilot handle pressure.

[0042] In an embodiment including two main pumps, the formula for calculating the instantaneous required power of the main pump according to the instantaneous pressure of the main pump and the instantaneous required displacement of the main pump is:

[0043] ;

[0044] In the formula, is the instantaneous pressure of the first main pump, is the instantaneous required displacement of the first main pump, is the instantaneous pressure of the second main pump, is the instantaneous required displacement of the second main pump, is the engine speed.

[0045] Step 4: Control the main pump output power according to the instantaneous limited power of the engine and the instantaneous required power of the main pump.

[0046] Specifically, in response to the instantaneous power demand of the main pump being not greater than the instantaneous power limit of the engine, the main pump output power is controlled to be equal to the instantaneous power demand of the main pump; in response to the instantaneous power demand of the main pump being greater than the instantaneous power limit of the engine, the main pump output power is controlled to be equal to the instantaneous power limit of the engine.

[0047] It should be noted that the instantaneous limited power of the engine and the instantaneous required power of the main pump are both instantaneous values. The two values ​​need to be compared to obtain the actual output power of the main pump of the hydraulic system, so as to ensure the accurate match between the actual output power of the main pump of the hydraulic system and the engine power.

[0048] Example 2

[0049] Based on the first embodiment, this embodiment provides a more comprehensive control method for a positive flow system hydraulic excavator.

[0050] In addition to the steps in Example 1, the method provided in this embodiment further includes: the controller controls the output displacement of the main pump according to the magnitude of the instantaneous limited power of the engine and the instantaneous required power of the main pump.

[0051] Specifically, in response to the instantaneous power demand of the main pump being not greater than the instantaneous power limit of the engine, the main pump output displacement is controlled to be equal to the instantaneous power demand of the main pump; in response to the instantaneous power demand of the main pump being greater than the instantaneous power limit of the engine, the corresponding main pump output displacement is calculated according to the instantaneous power limit of the engine.

[0052] In an embodiment including two main pumps, the corresponding main pump output displacement is calculated according to the instantaneous limited power of the engine, including:

[0053] ;

[0054] ;

[0055] In the formula, is the output displacement of the first main pump, is the output displacement of the second main pump, is the output power of the first main pump, is the output power of the second main pump, and equal.

[0056] In a specific embodiment, the method further includes: converting the main pump output displacement into the solenoid valve output current according to a preset displacement-current relationship curve.

[0057] The present invention utilizes the engine intake pressure to match the proportional solenoid valve current of the hydraulic pump, which can greatly improve the performance of the excavator.

[0058] Example 3

[0059] This embodiment provides a control system for a positive flow system hydraulic excavator, and the control system is used to implement the control method for the positive flow system hydraulic excavator as described in Example 1 or Example 2.

[0060] The control system includes: a controller, an instantaneous operation parameter acquisition unit and a pressure acquisition unit;

[0061] The instantaneous operation parameter acquisition unit and the pressure acquisition unit are respectively connected to the controller for communication;

[0062] The controller is used to calculate the instantaneous limiting power according to the instantaneous operating parameters of the engine collected by the instantaneous operating parameter collection unit, calculate the instantaneous required power of the main pump according to the pressure data collected by the pressure collection unit, and control the output power of the main pump according to the magnitude of the instantaneous limiting power of the engine and the instantaneous required power of the main pump.

[0063] In a specific embodiment, the controller is also used to: control the main pump output displacement according to the instantaneous limited power of the engine and the instantaneous required power of the main pump, and convert the main pump output displacement into the solenoid valve output current according to a preset displacement-current relationship curve.

[0064] In a specific embodiment, the pressure acquisition unit includes: a first pressure sensor for acquiring a pressure value of the main pump and a second pressure sensor for acquiring a pressure value of the pilot handle.

[0065] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A control method for a positive flow system hydraulic excavator, characterized in that: include: Obtain the instantaneous operating parameters of the engine, main pump pressure and pilot handle pressure; Calculating the instantaneous limited power of the engine according to the instantaneous operating parameters of the engine; Calculating the instantaneous power demand of the main pump according to the main pump pressure and the pilot handle pressure; In response to the instantaneous power demand of the main pump being not greater than the instantaneous limited power of the engine, controlling the output power of the main pump to be equal to the instantaneous power demand of the main pump; In response to the instantaneous required power of the main pump being greater than the instantaneous limited power of the engine, the output power of the main pump is controlled to be equal to the instantaneous limited power of the engine.

2. The control method of a positive flow system hydraulic excavator according to claim 1, characterized in that: The calculating the instantaneous required power of the main pump according to the main pump pressure and the pilot handle pressure includes: The main pump pressure is subjected to second-order filtering to obtain the main pump instantaneous pressure; According to the pilot handle pressure, the effective stroke of the pilot handle is calibrated to obtain the instantaneous required displacement of the main pump; The instantaneous required power of the main pump is calculated according to the instantaneous pressure of the main pump and the instantaneous required displacement of the main pump.

3. The control method of a positive flow system hydraulic excavator according to claim 2, characterized in that: Also includes: In response to the instantaneous required power of the main pump being not greater than the instantaneous limited power of the engine, controlling the output displacement of the main pump to be equal to the instantaneous required displacement of the main pump; In response to the instantaneous required power of the main pump being greater than the instantaneous limited power of the engine, the corresponding main pump output displacement is calculated according to the instantaneous limited power of the engine.

4. The control method of a positive flow system hydraulic excavator according to claim 3, characterized in that: Also includes: The main pump output displacement is converted into the solenoid valve output current according to a preset displacement-current relationship curve.

5. The control method of a positive flow system hydraulic excavator according to claim 3, characterized in that: The instantaneous operating parameters of the engine include: intake pressure parameters, engine speed, torque percentage and instantaneous fuel consumption.

6. The control method of a positive flow system hydraulic excavator according to claim 5, characterized in that: The main pump comprises a first main pump and a second main pump; The calculation formula of the instantaneous required power of the main pump is: ; In the formula, is the instantaneous pressure of the first main pump, is the instantaneous required displacement of the first main pump, is the instantaneous pressure of the second main pump, is the instantaneous required displacement of the second main pump, is the engine speed.

7. The control method of a positive flow system hydraulic excavator according to claim 6, characterized in that: The calculating the corresponding main pump output displacement according to the instantaneous limited power of the engine includes: ； ； In the formula, is the output displacement of the first main pump, is the output displacement of the second main pump, is the output power of the first main pump, is the output power of the second main pump, and equal.

8. A control system for a positive flow system hydraulic excavator, characterized in that: The control system is used to implement the control method of the positive flow system hydraulic excavator according to any one of claims 1 to 7; the control system comprises: a controller, an instantaneous operation parameter acquisition unit and a pressure acquisition unit; The instantaneous operation parameter acquisition unit and the pressure acquisition unit are respectively connected to the controller for communication; The controller is used to calculate the instantaneous power limit of the engine according to the instantaneous operating parameters of the engine collected by the instantaneous operating parameter collection unit, calculate the instantaneous required power of the main pump according to the pressure data collected by the pressure collection unit, and control the output power of the main pump according to the magnitude of the instantaneous power limit of the engine and the instantaneous required power of the main pump.

9. The control system of a positive flow system hydraulic excavator according to claim 8, characterized in that: The controller is also used to control the main pump output displacement according to the instantaneous limited power of the engine and the instantaneous required power of the main pump, and convert the main pump output displacement into the solenoid valve output current according to a preset displacement-current relationship curve.

10. The control system of a positive flow system hydraulic excavator according to claim 8 or 9, characterized in that: The pressure acquisition unit comprises: a first pressure sensor for acquiring the pressure of the main pump and a second pressure sensor for acquiring the pressure of the pilot handle.

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