A control method and system for a positive flow system hydraulic excavator

Abstract

This invention provides a control method and system for a positive flow hydraulic excavator, belonging to the field of excavator control technology. The method includes: acquiring instantaneous engine operating parameters, main pump pressure, and pilot handle pressure; calculating the instantaneous engine power limit based on the instantaneous engine operating parameters; calculating the instantaneous main pump power demand based on the main pump pressure and pilot handle pressure; and controlling the main pump output power based on the magnitude of the engine power limit and the main pump power demand. This invention achieves precise matching between the hydraulic system output power and engine power by continuously comparing the engine power limit and the main pump power demand, resulting in superior fuel efficiency and significantly improving excavator performance.

Description

Technical Field

[0001] This invention relates to a control method and system for a positive flow hydraulic excavator, belonging to the field of excavator control technology. Background Technology

[0002] my country's construction machinery industry has developed rapidly, with excavators playing an indispensable and dominant role. Due to national environmental protection and energy conservation requirements, higher demands are now being placed on the smoke emission, fuel consumption, efficiency, and operability of hydraulic excavators. For positive flow system hydraulic excavators, the proper matching of the engine and pump directly determines the excavator's fuel consumption, efficiency, smoke emission, and other performance characteristics.

[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 lead to negative effects such as engine speed drop and increased smoke. Existing positive flow system power limiting is divided into two types: one is the power gradient loading limiting disclosed in CN110644564A; the other is the power limiting 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 specific gear and limits the maximum hydraulic system power to this limit. It then applies the hydraulic power using a fixed ramp, making precise control of the loading process impossible. If the hydraulic system power is loaded too quickly, it can easily exceed the engine's power supply capacity, leading to adverse effects. Conversely, loading too slowly results in insufficient vehicle efficiency. In contrast, the power limiting method based on the engine's maximum available torque accurately reflects the engine's instantaneous power supply capacity. Limiting the hydraulic system power based on this ensures maximum engine power utilization efficiency. However, this parameter is not accurately provided by all engine brands, making widespread adoption difficult.

[0005] In summary, a better power limiting control strategy is needed to ensure an approximate fit between the torque provided by the engine and the torque loaded by the pump. Summary of the Invention

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

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution:

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

[0009] Furthermore, the calculation of the instantaneous power demand of the main pump based on the main pump pressure and the pilot handle pressure includes:

[0010] The main pump pressure is processed by a second-order filter to obtain the instantaneous pressure of the main pump;

[0011] The instantaneous required displacement of the main pump is obtained by calibrating the effective stroke of the pilot handle based on the pressure introduced by the pilot handle.

[0012] The instantaneous power demand of the main pump is calculated based on the instantaneous pressure and instantaneous displacement demand of the main pump.

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

[0014] If the instantaneous power demand of the main pump is greater than the instantaneous power limit of the engine, the corresponding output displacement of the main pump is calculated based on the instantaneous power limit 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 formula for calculating the instantaneous power demand of the main pump is:

[0018] ;

[0019] In the formula, The instantaneous pressure of the first main pump. For the instantaneous required displacement of the first main pump, This is the instantaneous pressure of the second main pump. To meet the instantaneous displacement demand of the second main pump, This refers to the engine speed.

[0020] Furthermore, the step of calculating the corresponding main pump output displacement based on the instantaneous power limit of the engine includes:

[0021] ;

[0022] ;

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

[0024] Secondly, 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 includes: 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 based on the instantaneous operating parameters of the engine acquired by the instantaneous operating parameter acquisition unit, calculate the instantaneous demand power of the main pump based on the pressure data acquired by the pressure acquisition unit, and control the output power of the main pump based on the magnitude of the instantaneous limiting power of the engine and the instantaneous demand power of the main pump.

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

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

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0028] (1) In this invention, when the controller starts working, the current maximum available power of the engine is calculated using the instantaneous operating parameters of the engine, which is used as the instantaneous limiting power of the engine, and the output power of the main pump is limited accordingly. At the same time, the instantaneous demand power of the main pump is calculated based on the pressure of the main pump and the pressure of the pilot handle. Both the instantaneous limiting power of the engine and the instantaneous demand power of the main pump are instantaneous values, and the two values ​​need to be compared continuously to obtain the actual output power of the main pump. This method achieves precise matching between the output power of the hydraulic system and the power of the engine, resulting in better fuel efficiency characteristics and greatly improving the performance of the excavator.

[0029] (2) The two parameters used in this invention, namely the engine intake pressure signal and the engine instantaneous fuel consumption, are directly obtained from the engine sensor. All engines can acquire these two parameters, and the method of calculating the engine instantaneous maximum available power using these two parameters is generalizable. Attached Figure Description

[0030] Figure 1 This is a flowchart of the control method for a positive flow system hydraulic excavator provided in Embodiment 1 of the present invention. Detailed Implementation

[0031] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0032] Example 1

[0033] This invention provides a control method for a positive flow system hydraulic excavator, such as... Figure 1 As shown, it includes:

[0034] Step 1: Obtain the instantaneous operating parameters of the engine, the main pump pressure, and the 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 acquired by the instantaneous operating parameter acquisition unit and stored in the engine ECU. The engine ECU and the controller are connected via a CAN bus. 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 power limit of the engine based on the instantaneous operating parameters of the engine.

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

[0039] Step 3: Calculate the instantaneous power demand of the main pump based on the main pump pressure and the pilot handle pressure.

[0040] Specifically, the instantaneous pressure and instantaneous displacement of the main pump are first obtained based on the collected main pump pressure and pilot handle pressure, and then the instantaneous power demand of the main pump is calculated based on the instantaneous pressure and instantaneous displacement demand of the main pump.

[0041] In a specific embodiment, the instantaneous pressure of the main pump is obtained by passing the main pump pressure through a second-order filter; and the instantaneous required displacement of the main pump is obtained by calibrating the effective stroke of the pilot handle based on the pilot handle pressure.

[0042] In an embodiment including two main pumps, the formula for calculating the instantaneous power demand of the main pumps based on the instantaneous pressure and instantaneous displacement demand of the main pumps is as follows:

[0043] ;

[0044] In the formula, The instantaneous pressure of the first main pump. For the instantaneous required displacement of the first main pump, This is the instantaneous pressure of the second main pump. To meet the instantaneous displacement demand of the second main pump, This refers to the engine speed.

[0045] Step 4: Control the output power of the main pump according to the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump.

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

[0047] It is important to note that both the engine's instantaneous power limit and the main pump's instantaneous power demand are instantaneous values. The two values ​​need to be constantly compared to determine the actual output power of the hydraulic system's main pump, thereby ensuring a precise match between the actual output power of the hydraulic system's main pump and the engine's power.

[0048] Example 2

[0049] Based on Example 1, this example 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 example also includes: the controller controlling the output displacement of the main pump according to the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump.

[0051] Specifically, in response to the instantaneous power demand of the main pump not being greater than the instantaneous power limit of the engine, the output displacement of the main pump 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 output displacement of the main pump is calculated based on the instantaneous power limit of the engine.

[0052] In an embodiment including two main pumps, the corresponding main pump output displacement is calculated based on the engine's instantaneous power limit, including:

[0053] ;

[0054] ;

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

[0056] In a specific embodiment, the method further 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.

[0057] This 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, which is used to implement the control method for the positive flow system hydraulic excavator as described in Embodiment 1 or Embodiment 2.

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

[0061] The instantaneous operating 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 power limit based on the instantaneous engine operating parameters collected by the instantaneous operating parameter acquisition unit, calculate the instantaneous power demand of the main pump based on the pressure data collected by the pressure acquisition unit, and control the output power of the main pump based on the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump.

[0063] In a specific embodiment, the controller is further configured to: control the output displacement of the main pump according to the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump, and convert the output displacement of the main pump into the output current of the solenoid valve according to a preset displacement-current relationship curve.

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

[0065] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A control method for a positive flow system hydraulic excavator, characterized in that, include: Acquire instantaneous engine operating parameters, main pump pressure, and pilot handle pressure; Calculate the instantaneous engine power limit based on the instantaneous engine operating parameters; Calculate the instantaneous power demand of the main pump based on the main pump pressure and the pilot handle pressure; In response to the fact that the instantaneous power demand of the main pump is not greater than the instantaneous power limit of the engine, the output power of the main pump 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 output power of the main pump is controlled to be equal to the instantaneous power limit of the engine; The calculation of the instantaneous power demand of the main pump based on the main pump pressure and the pilot handle pressure includes: The main pump pressure is processed by a second-order filter to obtain the instantaneous pressure of the main pump; The instantaneous required displacement of the main pump is obtained by calibrating the effective stroke of the pilot handle based on the pressure introduced by the pilot handle. Calculate the instantaneous power demand of the main pump based on the instantaneous pressure and instantaneous displacement demand of the main pump; The control method further includes: in response to the instantaneous power demand of the main pump not being greater than the instantaneous power limit of the engine, controlling the output displacement of the main pump to be equal to the instantaneous power demand of the main pump; If the instantaneous power demand of the main pump is greater than the instantaneous power limit of the engine, the corresponding output displacement of the main pump is calculated based on the instantaneous power limit of the engine. The main pump output displacement is converted into the solenoid valve output current according to the preset displacement-current relationship curve; The instantaneous operating parameters of the engine include: intake pressure parameters, engine speed, torque percentage, and instantaneous fuel consumption.

2. The control method for a positive flow system hydraulic excavator according to claim 1, characterized in that, The main pump includes a first main pump and a second main pump; The formula for calculating the instantaneous power demand of the main pump is as follows: In the formula, The instantaneous pressure of the first main pump. For the instantaneous required displacement of the first main pump, This is the instantaneous pressure of the second main pump. To meet the instantaneous displacement demand of the second main pump, This refers to the engine speed.

3. The control method for a positive flow system hydraulic excavator according to claim 2, characterized in that, The step of calculating the corresponding main pump output displacement based on the engine instantaneous power limit includes: ； ； In the formula, This refers to the output displacement of the first main pump. This is the output displacement of the second main pump. This is the output power of the first main pump. This is the output power of the second main pump. and equal.

4. A control system for a positive flow hydraulic excavator, characterized in that, The control system is used to implement the control method of the positive flow system hydraulic excavator as described in any one of claims 1-3; the control system includes: 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 connected to the controller for communication. The controller is used to calculate the instantaneous power limit of the engine based on the instantaneous operating parameters of the engine collected by the instantaneous operating parameter acquisition unit, calculate the instantaneous power demand of the main pump based on the pressure data collected by the pressure acquisition unit, and control the output power of the main pump based on the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump.

5. The control system of the positive flow system hydraulic excavator according to claim 4, characterized in that, The controller is also used to: control the output displacement of the main pump according to the magnitude of the instantaneous power limit of the engine and the instantaneous power demand of the main pump, and convert the output displacement of the main pump into the output current of the solenoid valve according to the preset displacement-current relationship curve.

6. The control system of the positive flow system hydraulic excavator according to claim 5, characterized in that, The pressure acquisition unit includes 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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