Control method and control system for rotating speed of cooling fan of loading machine and medium

Abstract

The embodiment of the invention relates to a method and system for controlling the rotating speed of a cooling fan of a loader and a medium, and belongs to the technical field of cooling fans of loaders, the control method comprises the steps that the double-closed-loop control process of the rotating speed of the fan is executed, and the rotating speed of the fan is calculated through a PD calculation method; based on the rotating speed target value of the cooling fan, the actual hydraulic pressure value at the current moment and the actual hydraulic pressure values at the first two moments, an expected output current value at the current moment is obtained; calculating the expected voltage value of the electric control valve core at the current moment based on the expected output current value at the current moment, the actual output current value at the current moment, the actual output current value at the last moment and the target rotating speed value of the cooling fan by utilizing a PI calculation method; accurate control of the rotating speed of the fan is achieved, the hysteresis problem of a control valve element is avoided, and the rotating speed of the cooling fan is closer to the ideal target rotating speed.

Description

Technical Field

[0001] The present application relates to the technical field of loader cooling fans, and more specifically, to a method, a control system and a medium for controlling the rotation speed of a loader cooling fan. Background Art

[0002] The cooling fan on the loader is controlled to rotate to effectively dissipate heat for the engine, etc. However, the cooling fan of the existing loader rotates for a long time and makes a lot of noise. Although the cooling fan has independent heat dissipation and realizes graded control, the graded control is not accurate, resulting in high fuel consumption of the cooling fan, and the constant speed when working and not working causes additional fuel consumption. In addition, the cooling fan is only controlled based on the temperature of the engine, resulting in the engine still running at a high speed when the temperature does not reach a higher temperature, resulting in additional fuel consumption of the cooling fan. Long-term forward rotation of the cooling fan will cause foreign matter to block the cooling fan. There is a hysteresis problem with the control valve core, and the valve core responds slowly or does not respond under low temperature conditions. Summary of the invention

[0003] The present application is provided to solve the above defects existing in the prior art. A control method, control system and medium for the speed of a loader cooling fan are needed to solve the problem of inaccurate fan speed control of the cooling fan and the hysteresis problem of the control valve core.

[0004] In a first aspect of the present application, a method for controlling the speed of a loader cooling fan is provided, the control method comprising: obtaining a target speed value of the cooling fan; executing a dual closed-loop control process of the fan speed, the dual closed-loop control process of the fan speed comprising: obtaining an actual value of the hydraulic pressure of the pressure sensor and an actual value of the current of the electric control valve core, the hydraulic pressure value comprising an actual value of the hydraulic pressure at a current moment and an actual value of the hydraulic pressure at two previous moments; using a PD calculation method to obtain an expected output current at a current moment based on the target speed value of the cooling fan, the actual value of the hydraulic pressure at a current moment, and the actual value of the hydraulic pressure at two previous moments; using a PI calculation method to calculate an expected voltage value of the electric control valve core at a current moment based on the expected output current at a current moment, the actual output current at a current moment, the actual output current at a previous moment, and the target speed value of the cooling fan; outputting the expected voltage value of the electric control valve core at a current moment to the electric control valve core, outputting the expected output current value at a current moment, and obtaining a real-time cooling fan speed; and repeating the dual closed-loop control process of the fan speed when the real-time cooling fan speed is less than or greater than the target speed value.

[0005] In a second aspect of the present application, a control system for a loader cooling fan speed is provided, the control system comprising a vehicle controller, a pressure sensor, an electrically controlled solenoid valve and a cooling fan, the vehicle controller being configured to: obtain a cooling fan speed target value; execute a double closed-loop control process of the fan speed, the double closed-loop control process of the fan speed comprising: obtaining an actual hydraulic pressure value of the pressure sensor and an actual current value of the electrically controlled valve core, the hydraulic pressure value comprising an actual hydraulic pressure value at a current moment and an actual hydraulic pressure value at two previous moments; utilizing a PD calculation method to calculate the cooling fan speed target value, the actual hydraulic pressure value at a current moment, and the actual hydraulic pressure value at a current moment; The expected value of the output current at the current moment is obtained by calculating the actual value of the hydraulic pressure at the previous two moments; the expected value of the voltage of the electric control valve core at the current moment is calculated by using the PI calculation method based on the expected value of the output current at the current moment, the actual value of the output current at the current moment, the actual value of the output current at the previous moment, and the target speed of the cooling fan; the expected value of the voltage of the electric control valve core at the current moment is output to the electric control valve core, the expected value of the output current at the current moment is output, and the real-time cooling fan speed is obtained; when the real-time cooling fan speed is less than or greater than the speed target value, the double closed-loop control process of the fan speed is repeated.

[0006] A third aspect of the present application provides a non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, executes the steps of a method for controlling the speed of a loader cooling fan as described in any embodiment of the present application.

[0007] The control methods, control systems and media for the loader cooling fan speed provided in various embodiments of the present application utilize the PD method to perform closed-loop output of the expected value of the electric control valve core current according to the feedback pressure, and utilize the PI method to perform closed-loop control of the output of the electric control valve core voltage according to the feedback current. Through a dual closed-loop control method, precise control of the fan speed is achieved, and the hysteresis problem of the control valve core is avoided, so as to reduce the influence of the hysteresis of the control valve core on the cooling fan, and make the speed of the cooling fan closer to the ideal target speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the embodiments applied for. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0009] Figure 1A flow chart showing a method for controlling the speed of a loader cooling fan according to an embodiment of the present application; Figure 2 A flow chart showing a method for determining a target speed value according to an embodiment of the present application; Figure 3 A structural schematic diagram showing a control system for the cooling fan speed of a loader according to an embodiment of the present application. DETAILED DESCRIPTION

[0010] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application is described in detail below in conjunction with the accompanying drawings and specific implementation examples. The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific implementation examples, but are not intended to limit the present application.

[0011] The words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0012] According to an embodiment of the present application, a method for controlling the speed of a loader cooling fan is provided, and the control method comprises the following steps: In step 101, a speed target value of the cooling fan is obtained. The speed target value is an ideal fan speed so as to achieve an ideal cooling effect.

[0013] In step 102, a double closed-loop control process of the fan speed is executed, and the double closed-loop control process of the fan speed includes the following steps. In step 1021, the actual value of the hydraulic pressure of the pressure sensor and the actual value of the current of the electronically controlled valve core are obtained, and the hydraulic pressure value includes the actual value of the hydraulic pressure at the current moment and the actual values ​​of the hydraulic pressure at the previous two moments. The pressure sensor detects the hydraulic pressure flowing through the hydraulic motor. The current of the electronically controlled valve core is controlled by the output of the vehicle controller.

[0014] In step 1022, the PD calculation method is used to obtain the output current expected value at the current moment based on the speed target value of the cooling fan, the actual value of the hydraulic pressure at the current moment, the actual value of the hydraulic pressure at the previous two moments, and the expected value of the hydraulic pressure at the previous two moments. Compared with the PID calculation method, the present application selects the PD algorithm according to the actual operation of the loader. The PD algorithm can bring an effect that is more in line with the actual situation, so that its results can be more accurate and closer to the expected value. Among them, the expected value is the ideal value corresponding to the speed target value of the cooling fan, such as the output current expected value at the last moment, which corresponds to the ideal current value corresponding to the speed target value at the last moment. The speed target value of the cooling fan can include the speed target value of the previous one or more moments. It is carried out continuously during the operation of the vehicle controller, so the speed target value of the cooling fan at the last moment can be stored to obtain the current expected value, voltage expected value, etc., or the current expected value, voltage expected value, etc. corresponding to the speed target value of the cooling fan at the last moment can be directly stored. When calculating, the corresponding data can be retrieved.

[0015] In step 1023, the PI calculation method is used to calculate the expected voltage value of the electric control valve core at the current moment based on the expected output current value at the current moment, the actual output current value at the current moment, the actual output current value at the previous moment, and the target speed value of the cooling fan. Compared with the PID calculation method, the present application selects the PI algorithm according to the actual operation of the loader. The PI algorithm can bring more practical results, making its results more accurate and closer to the expected value.

[0016] In step 1024, the expected voltage value of the electric control valve core at the current moment is output to the electric control valve core, the expected output current value at the current moment is output, and the real-time speed of the cooling fan is obtained; In step 103, when the real-time cooling fan speed is less than or greater than the speed target value, the fan speed double closed-loop control process is repeated. The double closed-loop control process is performed continuously so that the expected value can be closer to the speed target value, achieving a more ideal cooling effect.

[0017] The electric control valve core is an electromagnetic component, and its resistance value is greatly affected by temperature. When it is low temperature, it will seriously affect its control and even cause control failure. Although the fan speed is proportional to the control current, the electric control valve core is an electromagnetic component and has a hysteresis phenomenon. If the control method is only proportional to the current and the fan speed, the accuracy will be low. Through the control method of this application, the influence of the electric control valve core on the speed output can be reduced to approach the ideal speed.

[0018] In some embodiments, using the PD calculation method, based on the speed target value of the cooling fan, the actual value of the hydraulic pressure at the current moment, the actual values ​​of the hydraulic pressure at the previous two moments, and the expected values ​​of the hydraulic pressure at the previous two moments, the expected value of the output current at the current moment is obtained, which includes: The expected value of the output current at the current moment is calculated using formula (1): Δu(k)=u(k)−u(k−1)=KP[e(k)−e(k−1)]+KD[e(k)−2e(k−1)+e(k−2)] (1) Among them, Δu(k) represents the expected difference in output current, u(k) represents the expected value of output current at the current moment, u(k−1) represents the expected value of output current at the previous moment, k represents time, KP represents the proportional control parameter adjusted by experiment, KD represents the differential control parameter adjusted by experiment, e(k) represents the difference between the actual value of hydraulic pressure and the expected value of hydraulic pressure at the current moment, e(k−1) represents the difference between the actual value of hydraulic pressure and the expected value of hydraulic pressure at the previous moment, and e(k−2) represents the difference between the actual value of hydraulic pressure and the expected value of hydraulic pressure at the second moment before.

[0019] Compared with the PID algorithm, in this application, KI=0 is set, which is PD control. Using PD control can make the control more stable. For hydraulic pressure, it directly drives the fan to work by driving the hydraulic motor. When the fan is working, it is easily affected by the environment and causes load changes, which will affect the hydraulic pressure and cause slight fluctuations in the hydraulic pressure. Therefore, the PD algorithm is selected instead of the traditional PID algorithm. Removing the I phase makes PD more stable than the traditional PID algorithm, but the rapidity is affected to a certain extent. However, in this system, rapid response is not required. At the same time, reducing the rapidity of response means that the fan speed response becomes slower, that is, the adjustment time is extended, which reduces the pressure caused by the rapid speed increase of the fan and extends the life of the hydraulic motor and fan blades.

[0020] In some embodiments, the PI calculation method is used to calculate the expected voltage value of the electric control valve core at the current moment based on the expected output current value at the current moment, the actual output current value at the current moment, the actual output current value at the previous moment, and the target speed value of the cooling fan, including: using formula (2) to calculate the expected voltage value of the electric control valve core at the current moment, Δu(k)=u(k)−u(k−1)=KP[e(k)−e(k−1)]+KIe(k) (2) Among them, Δu(k) represents the expected difference in the voltage value of the electronically controlled spool valve, u(k) represents the expected voltage value of the electronically controlled spool valve at the current moment, u(k−1) represents the expected voltage value of the electronically controlled spool valve at the previous moment, k represents time, KP represents the tuned proportional control parameter obtained through experiments, KI represents the tuned integral control parameter obtained through experiments, e(k) represents the difference between the actual output current value and the expected output current value at the current moment, and e(k−1) represents the difference between the actual output current value and the expected output current value at the previous moment.

[0021] In this application, compared with the PID algorithm, PD is set to 0, which is the PI control. The purpose of using the PI algorithm is to make the control faster and more accurate, and the characteristics of PI are fast and accurate. For current control, it directly controls the electronically controlled spool valve and is less affected by interference during the control process. Therefore, compared with PID control, PI control is selected here, sacrificing the anti-interference ability to noise and obtaining a faster and more accurate ability. Since the current in this system is less affected by interference, the requirement for anti-interference ability is not high, but the requirements for fastness and accuracy are high. Selecting PI control can better cooperate with the hydraulic pressure closed-loop control and increase the coordination and cooperation of the double closed-loop control.

[0022] The KP coefficient, KD coefficient, and KI coefficient can be determined by evaluating the heat dissipation effect based on the actual results during the operation of the loader under multiple coefficient values.

[0023] In some embodiments, the control method further includes determining the rotational speed target value by looking up a table, which includes the following steps. In step 201, based on the current coolant water temperature of the engine, compare it with the preset gear setting values in the water temperature table to determine the first rotational speed value of the fan. In step 202, based on the current transmission oil temperature, compare it with the preset gear setting values in the oil temperature table to determine the second rotational speed value of the fan. In step 203, based on the first rotational speed target value and the second rotational speed target value, select the larger value as the rotational speed target value. The gears corresponding to the rotational speed target values in the water temperature table and the oil temperature table are the same. The transmission oil temperature is the oil temperature of the transmission system of the loader.

[0024] For example, the gear setting values of the engine coolant water temperature are divided into T1, T2, T3, T4, and the maximum rotational speeds of the corresponding cooling fans are V1, V2, V3, V4; the gear setting values of the transmission oil temperature are divided into W1, W2, W3, W4, and the maximum rotational speeds of the cooling fans are V1, V2, V3, V4. The rotational speed control method in this application uses temperature grading control. Select the gear with the highest temperature to determine the rotational speed to fully dissipate heat. If T < T1 and W < W1, the fan does not rotate.

[0025] In some embodiments, when the cooling water temperature is equal to the gear setting value, the speed target value corresponding to the gear setting value is selected as the first speed value; when the cooling water temperature is between two adjacent gear setting values, the speed target value corresponding to the larger gear setting value is selected as the first speed value. In this way, the loader can be sufficiently cooled.

[0026] In some embodiments, the control method further includes: when the cooling water temperature is greater than the minimum gear setting value in the water temperature table, and the transmission oil temperature is less than the minimum gear setting value in the oil temperature table; or, when the cooling water temperature is less than the minimum gear setting value in the water temperature table, and the transmission oil temperature is greater than the minimum gear setting value in the oil temperature table, selecting the speed target value corresponding to the lowest gear. As long as one of the cooling water temperature or the transmission oil temperature is less than the lowest gear and the other is greater than the lowest gear, the speed target value corresponding to the lowest gear is required for heat dissipation, which can achieve both heat dissipation effect and reduce energy consumption.

[0027] In some embodiments, when the speed target value corresponding to the cooling water temperature at the current moment is determined, and the difference between the cooling water temperature at the subsequent moment and the cooling water temperature at the current moment is less than the first threshold, the current first speed value is maintained; when the speed target value corresponding to the transmission oil temperature at the current moment is determined, and the difference between the transmission oil temperature at the subsequent moment and the transmission oil temperature at the current moment is less than the second threshold, the current second speed value is maintained. For example, the temperature of T1 enters the speed of v1, and the temperature of T2 enters the speed of V2, T2>T1, if the temperature is at T2 and the speed is V2, but the heat dissipation is excessive after the speed is increased and the temperature is a little lower than T2, it will immediately switch to V1, and after reaching V1, the heat dissipation is insufficient and the temperature reaches T2 again, and the speed reaches V2 again, so that the speed will jump repeatedly at a high frequency in this temperature range. Specifically, if 30° is set as the threshold, 29° is V1, and 31° is V2, if the temperature is always at 30°+-1°, the speed will jump continuously. Taking the first threshold of 5° as an example, the speed will be switched according to the gear only when the difference changes by more than 5°, which can avoid repeated jumps in the speed target value.

[0028] In some embodiments, the control method further includes determining a final speed target value of the cooling fan based on the speed of the engine, including: V = (Vmax-Vmin) / Smax*S Among them, V represents the final speed target value, Vmax represents the speed target value obtained by looking up the table, Vmin represents the minimum speed of the fan for heat dissipation when the vehicle is static at the current temperature, Smax represents the maximum speed of the engine, and S represents the current speed of the engine).

[0029] Based on the positive correlation between the engine speed and the current speed, the final speed target value is adjusted, because the higher the engine speed, the faster the fan speed, and the slower the engine speed, the lower the fan speed, but the current fan speed is still suitable for the current cooling speed. In this way, the speed is not only controlled according to the temperature, but also the engine can be fully cooled, and energy consumption can be reduced, the control accuracy can be significantly improved, and the cooling fan speed redundancy can be reduced.

[0030] The electric control valve core is an electromagnetic component, and its resistance value is greatly affected by temperature. When it is low in temperature, its control will be seriously affected and even the control will not respond. In some embodiments of the present application, after the loader is started, when the temperature reaches the fan working range, a suitable current value is passed into the electric control valve core. It is used to heat the electromagnetic valve core. This current is only used for heating and does not open the electric control valve core, so that the heating is out of the uncontrollable range of low temperature. When the fan is working, the valve core has been heated to the normal working range, which is more controlled and the service life of the valve core is extended.

[0031] In some embodiments, when the engine running time is less than 50 hours, the cooling fan rotates forward; when the engine running time is greater than or equal to 50 hours, the cooling fan rotates reversely. The reversal time can be set to 30 seconds, etc., to avoid the cooling fan running for a long time, resulting in foreign matter clogging. When reversing, the speed of the cooling fan is set to the maximum. The cooling fan can be interrupted by reversing during the forward rotation, but cannot be interrupted by the forward rotation during the reversing process.

[0032] According to an embodiment of the present application, a control system for the speed of a loader cooling fan is also provided. Figure 3As shown, the control system 300 includes a vehicle controller 301, a pressure sensor 302, an electric-controlled solenoid valve 303 and a cooling fan 304. The vehicle controller 301 is respectively connected to the pressure sensor 302, the electric-controlled solenoid valve 303 and the cooling fan 304 for communication. The vehicle controller 301 is configured to: obtain a target speed value of the cooling fan; execute a double closed-loop control process of the fan speed, and the double closed-loop control process of the fan speed includes: obtaining an actual value of the hydraulic pressure of the pressure sensor and an actual value of the current of the electric-controlled valve core, the hydraulic pressure value including an actual value of the hydraulic pressure at the current moment and an actual value of the hydraulic pressure at the previous two moments; using a PD calculation method, based on the cooling fan The speed target value, the actual value of the hydraulic pressure at the current moment, and the actual values ​​of the hydraulic pressure at the previous two moments are used to obtain the expected value of the output current at the current moment; the expected value of the voltage of the electric control valve core at the current moment is calculated by using the PI calculation method based on the expected value of the output current at the current moment, the actual value of the output current at the current moment, the actual value of the output current at the previous moment, and the speed target value of the cooling fan; the expected value of the voltage of the electric control valve core at the current moment is output to the electric control valve core, the expected value of the output current at the current moment is output, and the real-time cooling fan speed is obtained; when the real-time cooling fan speed is less than or greater than the speed target value, the double closed-loop control process of the fan speed is repeated.

[0033] The vehicle controller 301 reads the required data (such as engine temperature, transmission system temperature, engine running time, engine speed, reverse button status of the cooling fan, etc.) through CAN messages and sensors.

[0034] In some embodiments, the vehicle controller 301 is further configured to: use the PD calculation method to obtain the expected output current value at the last moment, the actual hydraulic pressure value at the current moment, the actual hydraulic pressure values ​​at the previous two moments, and the expected hydraulic pressure values ​​at the previous two moments, and the expected output current value at the current moment includes: The expected value of the output current at the current moment is calculated using formula (1): Δu(k)=u(k)-u(k-1)=KP[e(k)-e(k-1)]+KD[e(k)-2e(k-1)+e(k-2)] (1) Among them, Δu(k) represents the expected difference in output current, u(k) represents the expected value of output current at the current moment, u(k-1) represents the expected value of output current at the previous moment, k represents time, KP represents the adjusted proportional control parameter obtained through experiments, KD represents the adjusted differential control parameter obtained through experiments, e(k) represents the difference between the actual value of hydraulic pressure at the current moment and the expected value of hydraulic pressure, e(k-1) represents the difference between the actual value of hydraulic pressure at the previous moment and the expected value of hydraulic pressure, and e(k-2) represents the difference between the actual value of hydraulic pressure at the second previous moment and the expected value of hydraulic pressure.

[0035] In some embodiments, the vehicle controller 301 is further configured to: calculate the expected voltage value of the electric control valve core at the current moment based on the expected output current value at the current moment, the actual output current value at the current moment, the actual output current value at the last moment, the expected output current value at the last moment, and the expected voltage value of the electric control valve core at the last moment using the PI calculation method, including: calculating the expected voltage value of the electric control valve core at the current moment using formula (2), Δu(k)=u(k)-u(k-1)=KP[e(k)-e(k-1)]+KIe(k) (2) Among them, Δu(k) represents the expected difference in the voltage value of the electric control valve core, u(k) represents the expected voltage value of the electric control valve core at the current moment, u(k-1) represents the expected voltage value of the electric control valve core at the previous moment, k represents time, KP represents the adjusted proportional control parameter obtained through experiments, KI represents the adjusted integral control parameter obtained through experiments, e(k) represents the difference between the actual output current value and the expected output current value at the current moment, and e(k-1) represents the difference between the actual output current value and the expected output current value at the previous moment.

[0036] In some embodiments, the vehicle controller 301 is further configured to: determine the speed target value by looking up a table, including the following steps. Determine the first speed value of the fan by comparing the current cooling water temperature of the engine with the gear setting value pre-set in the water temperature table. Determine the second speed value of the fan by comparing the current transmission oil temperature with the gear setting value pre-set in the oil temperature table. According to the first speed target value and the second speed target value, select the larger value as the speed target value, and the gears of the speed target values ​​corresponding to the water temperature table and the oil temperature table are the same. The transmission oil temperature is the transmission oil temperature of the hydraulic motor.

[0037] For example, the gear setting values ​​of the engine cooling water temperature are divided into T1, T2, T3, T4, and the corresponding maximum speeds of the cooling fans are divided into V1, V2, V3, V4; the gear setting values ​​of the transmission oil temperature are divided into W1, W2, W3, W4, and the maximum speeds of the cooling fans are divided into V1, V2, V3, V4. The speed control method in this application adopts temperature graded control. The gear with the highest temperature is selected to determine the speed to fully dissipate heat.

[0038] In some embodiments, the vehicle controller 301 is further configured to: when the cooling water temperature is equal to the gear setting value, select the speed target value corresponding to the gear setting value as the first speed value; when the cooling water temperature is between two adjacent gear setting values, select the speed target value corresponding to the larger gear setting value as the first speed value. In this way, the loader can be sufficiently cooled.

[0039] In some embodiments, the vehicle controller 301 is further configured to: select the speed target value corresponding to the lowest gear when the cooling water temperature is greater than the minimum gear setting value in the water temperature table and the transmission oil temperature is less than the minimum gear setting value in the oil temperature table; or when the cooling water temperature is less than the minimum gear setting value in the water temperature table and the transmission oil temperature is greater than the minimum gear setting value in the oil temperature table. As long as one of the cooling water temperature or the transmission oil temperature is less than the lowest gear and the other is greater than the lowest gear, the speed target value corresponding to the lowest gear is required for heat dissipation, so as to achieve both heat dissipation effect and reduce energy consumption.

[0040] In some embodiments, the vehicle controller 301 is further configured to: when the speed target value corresponding to the cooling water temperature at the current moment is determined, and the difference between the cooling water temperature at a subsequent moment and the current moment is less than the first threshold, maintain the current first speed value; when the speed target value corresponding to the transmission oil temperature at the current moment is determined, and the difference between the transmission oil temperature at a subsequent moment and the current moment is less than the second threshold, maintain the current second speed value. Repeated jumps in the speed target value can be avoided.

[0041] In some embodiments, the vehicle controller 301 is further configured to: determine the final speed target value of the cooling fan based on the engine speed, including: V = (Vmax-Vmin) / Smax*S Among them, V represents the final speed target value, Vmax represents the speed target value obtained by looking up the table, Vmin represents the minimum speed of the fan for heat dissipation when the vehicle is static at the current temperature, Smax represents the maximum speed of the engine, and S represents the current speed of the engine). In some embodiments, the vehicle controller 301 may integrate a central processing unit (CPU) and a microcontroller unit (MCU). The processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc.

[0042] According to an embodiment of the present application, a non-transitory computer-readable medium is also provided, on which instructions are stored. When executed by a processor, the instructions execute the steps of the method for controlling the speed of a loader cooling fan as described in any embodiment of the present application.

[0043] In addition, although exemplary embodiments have been described herein, the scope includes any and all embodiments based on the present application with equivalent elements, modifications, omissions, combinations (e.g., various embodiments intersecting schemes), adaptations or changes. The elements in the claims are to be interpreted broadly based on the language adopted in the claims, and are not limited to the examples described in this specification or during the practice of this application, and the examples are to be interpreted as non-exclusive. Therefore, this specification and examples are intended to be considered as examples only, and the true scope and spirit are indicated by the following claims and the full scope of their equivalents.

[0044] The above description is intended to be illustrative rather than restrictive. For example, the above examples (or one or more schemes thereof) may be used in combination with each other. For example, a person of ordinary skill in the art may use other embodiments when reading the above description. In addition, in the above-mentioned specific embodiments, various features may be grouped together to simplify the present application. This should not be interpreted as an intention that a feature of an application that does not require protection is necessary for any claim. On the contrary, the subject matter of the present application may be less than all the features of an embodiment of a particular application. Thus, the following claims are incorporated herein in the specific embodiments as examples or embodiments, wherein each claim is independently a separate embodiment, and it is considered that these embodiments may be combined with each other in various combinations or arrangements. The scope of the present invention should be determined with reference to the appended claims and the full scope of equivalent forms granted by these claims.

[0045] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A method for controlling the speed of a loader cooling fan, characterized in that: The control method comprises: Get the target speed value of the cooling fan; A dual closed-loop control process for fan speed is executed, the dual closed-loop control process for fan speed comprising: obtaining an actual hydraulic pressure value of a pressure sensor and an actual current value of an electric control valve core, the hydraulic pressure value comprising an actual hydraulic pressure value at a current moment and an actual hydraulic pressure value at two previous moments; using a PD calculation method to obtain an expected output current value at a current moment based on a target speed value of a cooling fan, an actual hydraulic pressure value at a current moment, and an actual hydraulic pressure value at two previous moments; using a PI calculation method to calculate an expected voltage value of the electric control valve core at a current moment based on an expected output current value at a current moment, an actual output current value at a current moment, an actual output current value at a previous moment, and a target speed value of a cooling fan; outputting the expected voltage value of the electric control valve core at a current moment to the electric control valve core, outputting an expected output current value at a current moment, and obtaining a real-time cooling fan speed; When the real-time cooling fan speed is less than or greater than the speed target value, the double closed-loop control process of the fan speed is repeated.

2. The control method according to claim 1, characterized in that: Using the PD calculation method, based on the expected output current value at the last moment, the actual hydraulic pressure value at the current moment, the actual hydraulic pressure values ​​at the previous two moments, and the expected hydraulic pressure values ​​at the previous two moments, the expected output current value at the current moment is obtained, including: The expected value of the output current at the current moment is calculated using formula (1): Δu(k)=u(k)-u(k-1)=KP[e(k)-e(k-1)]+KD[e(k)-2e(k-1)+e(k-2)] (1) Among them, Δu(k) represents the expected difference in output current, u(k) represents the expected value of output current at the current moment, u(k-1) represents the expected value of output current at the previous moment, k represents time, KP represents the adjusted proportional control parameter obtained through experiments, KD represents the adjusted differential control parameter obtained through experiments, e(k) represents the difference between the actual value of hydraulic pressure at the current moment and the expected value of hydraulic pressure, e(k-1) represents the difference between the actual value of hydraulic pressure at the previous moment and the expected value of hydraulic pressure, and e(k-2) represents the difference between the actual value of hydraulic pressure at the second previous moment and the expected value of hydraulic pressure.

3. The control method according to claim 1, characterized in that: Using the PI calculation method, based on the expected output current value at the current moment, the actual output current value at the current moment, the actual output current value at the last moment, the expected output current value at the last moment, and the expected voltage value of the electric control valve core at the last moment, the expected voltage value of the electric control valve core at the current moment is calculated, including: using formula (2) to calculate the expected voltage value of the electric control valve core at the current moment, Δu(k)=u(k)-u(k-1)=KP[e(k)-e(k-1)]+KIe(k) (2) Among them, Δu(k) represents the expected difference in the voltage value of the electric control valve core, u(k) represents the expected voltage value of the electric control valve core at the current moment, u(k-1) represents the expected voltage value of the electric control valve core at the previous moment, k represents time, KP represents the adjusted proportional control parameter obtained through experiments, KI represents the adjusted integral control parameter obtained through experiments, e(k) represents the difference between the actual output current value and the expected output current value at the current moment, and e(k-1) represents the difference between the actual output current value and the expected output current value at the previous moment.

4. The control method according to claim 1, characterized in that: The control method further includes determining the speed target value by looking up a table, including: According to the current engine cooling water temperature, the first speed value of the fan is determined by comparing it with the gear setting value preset in the water temperature table; According to the current transmission oil temperature, the second speed value of the fan is determined by comparing it with the gear setting value preset in the oil temperature table; According to the first speed target value and the second speed target value, the larger value is selected as the speed target value, and the gears of the speed target values ​​corresponding to the water temperature table and the oil temperature table are the same.

5. The control method according to claim 1, characterized in that: When the cooling water temperature is equal to the gear setting value, the speed target value corresponding to the gear setting value is selected as the first speed value; When the cooling water temperature is between two adjacent gear setting values, the speed target value corresponding to the larger gear setting value is selected as the first speed value.

6. The control method according to claim 1, characterized in that: The control method also includes: when the cooling water temperature is greater than the minimum gear setting value in the water temperature table, and the transmission oil temperature is less than the minimum gear setting value in the oil temperature table; or, when the cooling water temperature is less than the minimum gear setting value in the water temperature table, and the transmission oil temperature is greater than the minimum gear setting value in the oil temperature table, selecting the speed target value corresponding to the lowest gear.

7. The control method according to claim 1, characterized in that: When the speed target value corresponding to the cooling water temperature and transmission oil temperature at the current moment is determined, and the difference between the cooling water temperature at a subsequent moment and the cooling water temperature at the current moment is less than the first threshold, and the difference between the transmission oil temperature at a subsequent moment and the transmission oil temperature at the current moment is less than the second threshold, the speed target value at the current moment is maintained.

8. The control method according to claim 1, characterized in that: The control method further includes determining a final speed target value of the cooling fan based on the speed of the engine, including: V=(Vmax-Vmin) / Smax*S Among them, V represents the final speed target value, Vmax represents the speed target value obtained by looking up the table, Vmin represents the minimum speed of the fan for the loader to meet the heat dissipation requirements under static conditions at the current temperature, Smax represents the maximum speed of the engine, and S represents the current speed of the engine).

9. A control system for the speed of a loader cooling fan, characterized in that: The control system includes a vehicle controller, a pressure sensor, an electrically controlled solenoid valve and a cooling fan. The vehicle controller is configured as follows: Get the target speed value of the cooling fan; A dual closed-loop control process for fan speed is executed, the dual closed-loop control process for fan speed comprising: obtaining an actual hydraulic pressure value of a pressure sensor and an actual current value of an electric control valve core, the hydraulic pressure value comprising an actual hydraulic pressure value at a current moment and an actual hydraulic pressure value at two previous moments; using a PD calculation method to obtain an expected output current value at a current moment based on a target speed value of a cooling fan, an actual hydraulic pressure value at a current moment, and an actual hydraulic pressure value at two previous moments; using a PI calculation method to calculate an expected voltage value of the electric control valve core at a current moment based on an expected output current value at a current moment, an actual output current value at a current moment, an actual output current value at a previous moment, and a target speed value of a cooling fan; outputting the expected voltage value of the electric control valve core at a current moment to the electric control valve core, outputting an expected output current value at a current moment, and obtaining a real-time cooling fan speed; When the real-time cooling fan speed is less than or greater than the speed target value, the double closed-loop control process of the fan speed is repeated.

10. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, execute the steps of the method for controlling the rotation speed of a loader cooling fan according to any one of claims 1 to 8.

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