Energy-saving control method and system for electric forklift

Abstract

The present invention discloses an energy-saving control method and system for an electric forklift, which relates to the technical field of motors, and includes obtaining the working state of a lifting circuit of a hydraulic system; obtaining the working state of a steering circuit of the hydraulic system; determining the rotation speed of a motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, and controlling the motor based on the rotation speed. The present application controls the motor to run at a corresponding rotation speed under various working states of the lifting circuit and the steering circuit of the hydraulic system, so that the motor runs according to its own working requirements, reduces energy consumption, and at the same time ensures that the hydraulic oil of the lifting circuit and the steering circuit of the hydraulic system is always sufficient under various working states, thereby avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil and improving the operating efficiency of the hydraulic system.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to an energy-saving control method and system for an electric forklift. Background Art

[0002] In recent years, with the rapid development of e-commerce and logistics industries, the market demand for electric forklifts has increased year by year. Compared with internal combustion forklifts, electric forklifts have the advantages of low noise and no pollution, and are very suitable for working in indoor environments. Because the hydraulic system of electric forklifts accounts for a large proportion of the energy consumption of the whole vehicle, the operating efficiency of the hydraulic system has become one of the focuses of energy consumption research. If the hydraulic system continues to operate inefficiently, it will not only directly affect the energy utilization efficiency and overall operating cost of the electric forklift, but also cause the oil temperature of the hydraulic oil to be too high, resulting in reduced equipment reliability. The hydraulic system of electric forklifts mostly adopts a structural solution that combines a single-displacement pump, a manual load-sensitive multi-way valve and a steering circuit. Under the same hydraulic system structure, the energy-saving effect can only be improved by optimizing the control solution of the motor speed.

[0003] There are currently two energy-saving control methods for electric forklifts: one method is to trigger the lifting enable signal after pulling the lifting handle, and the vehicle controller drives the motor to run at a constant full speed after receiving the lifting enable signal. Although it can meet the needs of the steering cylinder and / or lifting cylinder, many modes, such as idle mode, do not require the motor to run at full speed. This control method has high noise and high energy consumption; the other method is to only consider the lifting condition and control the motor speed according to the lifting condition. However, in this control method, in the combined steering and lifting mode, the hydraulic oil output by the metering pump will first be supplied to the steering cylinder through the steering valve, and the excess hydraulic oil will flow to the lifting cylinder through the lifting valve. The speed of the motor is related to the control flow of the lifting valve, which may easily lead to insufficient hydraulic oil in the lifting cylinder and uneven and jittery operation of the cylinder. Summary of the invention

[0004] The purpose of the present invention is to provide an energy-saving control method and system for an electric forklift, which can control the motor to operate according to its own working requirements, reduce energy consumption, and at the same time ensure that the hydraulic oil in the lifting circuit and steering circuit of the hydraulic system is always sufficient in various working conditions, thereby avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil and improving the operating efficiency of the hydraulic system. The specific scheme is as follows:

[0005] In a first aspect, the present application discloses an energy-saving control method for an electric forklift, comprising:

[0006] Acquire the working state of the lifting circuit of the hydraulic system, wherein the working state of the lifting circuit includes action and inaction;

[0007] Acquiring the working state of the steering circuit of the hydraulic system, wherein the working state of the steering circuit includes action and inaction;

[0008] The rotation speed of the motor of the hydraulic system is determined based on the working state of the lifting circuit and the working state of the steering circuit, so as to control the motor based on the rotation speed.

[0009] Optionally, the hydraulic system further comprises a potentiometer, which is mounted on a lifting valve in the lifting circuit and is used to detect the displacement of a valve core of the lifting valve;

[0010] Obtain the working status of the lifting circuit of the hydraulic system, including:

[0011] Acquiring a voltage signal collected by the potentiometer;

[0012] If the voltage signal is less than or equal to a preset voltage threshold, it is determined that the lifting circuit is in a non-actuating working state;

[0013] If the voltage signal is greater than a preset voltage threshold, it is determined that the lifting circuit is in an operating state.

[0014] Optionally, the hydraulic system further comprises a pressure sensor, which is installed at a load oil port of a steering gear in the steering circuit and is used to detect the pressure of a load at the load oil port;

[0015] Obtaining the working state of the steering circuit of the hydraulic system includes:

[0016] Acquiring a pressure signal collected by the pressure sensor;

[0017] If the pressure signal is less than or equal to a preset pressure threshold, it is determined that the steering circuit is in an inactive working state;

[0018] If the pressure signal is greater than a preset pressure threshold, it is determined that the steering circuit is in an actuated working state.

[0019] Optionally, if the lifting circuit is in an inactive working state, and the steering circuit is in an inactive working state;

[0020] Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes:

[0021] Determining that the hydraulic system is in an idle mode based on the inactive working state of the lifting circuit and the inactive working state of the steering circuit;

[0022] The rotation speed of the motor of the hydraulic system is determined to be a first rotation speed, wherein the first rotation speed is a preset minimum rotation speed, and the preset minimum rotation speed is smaller than the ratio of the maximum flow required by the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system.

[0023] Optionally, if the lifting circuit is in a non-actuated working state, and the steering circuit is in an acted working state;

[0024] Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes:

[0025] Determining that the hydraulic system is in a steering mode based on the inactive working state of the lifting circuit and the active working state of the steering circuit;

[0026] The rotation speed of the motor of the hydraulic system is determined to be a second rotation speed, wherein the second rotation speed is a ratio of a maximum flow required for a steering mode to a unit displacement of a fixed displacement pump.

[0027] Optionally, if the lifting circuit is in an actuated working state, and the steering circuit is in an inactive working state;

[0028] Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes:

[0029] Determining that the hydraulic system is in a lifting mode based on the lifting circuit being in an actuated working state and the steering circuit being in an inactive working state;

[0030] determining a control flow rate of the hoisting circuit;

[0031] If the lifting circuit is in the micro-motion operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is greater than the control flow rate of the lifting circuit;

[0032] If the lifting circuit is in the fast operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, wherein, when the lifting circuit is at the critical point between the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the control flow rate of the lifting circuit when the lifting circuit is at the critical point between the inching operation range and the fast operation range;

[0033] If the lifting circuit is in the maximum operating range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range;

[0034] The ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump is determined, and the ratio is used as the rotation speed of the motor of the hydraulic system.

[0035] Optionally, if the lifting circuit is in an actuated working state, and the steering circuit is in an actuated working state;

[0036] Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes:

[0037] Determining that the hydraulic system is in a steering and lifting combined mode based on the working state that the lifting circuit is in an actuated working state and the working state that the steering circuit is in an actuated working state;

[0038] determining a control flow rate of the hoisting circuit;

[0039] If the lifting circuit is in the inching operation range, determining that the flow rate provided by the metering pump in the hydraulic system is greater than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode;

[0040] If the lifting circuit is in the fast operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode, wherein, when the lifting circuit is at the critical point between the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode when the lifting circuit is at the critical point between the inching operation range and the fast operation range;

[0041] If the lifting circuit is in the maximum operating range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range;

[0042] The ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump is determined, and the ratio is used as the rotation speed of the motor of the hydraulic system.

[0043] In a second aspect, the present application discloses an energy-saving control system for an electric forklift, comprising:

[0044] A first acquisition module is used to acquire the working state of a lifting circuit of a hydraulic system, wherein the working state of the lifting circuit includes action and inaction;

[0045] A second acquisition module is used to acquire the working state of the steering circuit of the hydraulic system, where the working state of the steering circuit includes action and inaction;

[0046] A determination module is used to determine the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, so as to control the motor based on the rotation speed.

[0047] In a third aspect, the present application discloses an energy-saving control device for an electric forklift, comprising:

[0048] Memory, used to store computer programs;

[0049] The processor is used to execute the computer program to implement the steps of the electric forklift energy-saving control method as described above.

[0050] In a fourth aspect, the present application discloses a forklift, comprising a hydraulic system and an energy-saving control device for an electric forklift as described above, wherein the energy-saving control device for an electric forklift is connected to the hydraulic system.

[0051] The present application discloses an energy-saving control method and system for an electric forklift, which requires first obtaining the working state of the lifting circuit and the working state of the steering circuit of the hydraulic system, and determining the corresponding rotation speed according to the working state of the lifting circuit and the steering circuit, and controlling the motor at different rotation speeds, so as to achieve control of the motor at different rotation speeds under different working states of the lifting circuit and the steering circuit. As can be seen from the above, the present application controls the motor to run at a corresponding rotation speed under various working states of the lifting circuit and the steering circuit of the hydraulic system, so that the motor runs according to its own working requirements, reduces energy consumption, and at the same time ensures that the hydraulic oil of the lifting circuit and the steering circuit of the hydraulic system is always sufficient under various working states, thereby avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil and improving the operating efficiency of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0053] Figure 1 This is a flow chart of an energy-saving control method for an electric forklift disclosed in the present invention;

[0054] Figure 2 A working diagram of a hydraulic system disclosed in the present invention;

[0055] Figure 3A schematic diagram of a hydraulic system disclosed in the present invention;

[0056] Figure 4 A curve diagram showing the relationship between the voltage of a potentiometer disclosed in the present invention and the control flow of a lifting circuit;

[0057] Figure 5 A curve diagram showing the relationship between the flow rate provided by a quantitative pump and the voltage of a potentiometer in a lifting mode disclosed in the present invention;

[0058] Figure 6 A curve diagram showing the relationship between the flow rate provided by a quantitative pump and the voltage of a potentiometer in a combined steering and lifting mode disclosed in the present invention;

[0059] Figure 7 It is a flowchart of a specific electric forklift energy-saving control method disclosed in the present invention;

[0060] Figure 8 It is a structural schematic diagram of an energy-saving control system for an electric forklift disclosed in the present invention;

[0061] Fig. 9 The present invention is a structural diagram of an electronic device disclosed in the present invention. DETAILED DESCRIPTION

[0062] The core of the present invention is to provide an energy-saving control method and system for an electric forklift, which can control the motor to operate according to its own working requirements and reduce energy consumption, while ensuring that the hydraulic oil in the lifting circuit and steering circuit of the hydraulic system is always sufficient under various working conditions, avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil and improving the operating efficiency of the hydraulic system.

[0063] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] There are currently two energy-saving control methods for electric forklifts: one method is to trigger the lifting enable signal after pulling the lifting handle, and the vehicle controller drives the motor to run at a constant full speed after receiving the lifting enable signal. Although it can meet the needs of the steering cylinder and / or lifting cylinder, many modes, such as idle mode, do not require the motor to run at full speed. This control method has high noise and high energy consumption; the other method is to only consider the lifting condition and control the motor speed according to the lifting condition. However, in this control method, in the combined steering and lifting mode, the hydraulic oil output by the metering pump will first be supplied to the steering cylinder through the steering valve, and the excess hydraulic oil will flow to the lifting cylinder through the lifting valve. The speed of the motor is related to the control flow of the lifting valve, which may easily lead to insufficient hydraulic oil in the lifting cylinder and uneven and jittery operation of the cylinder.

[0065] See also Figure 1 As shown, Figure 1 The present invention discloses a flow chart of an energy-saving control method for an electric forklift.

[0066] The electric forklift energy-saving control method comprises:

[0067] S11, obtaining the working state of the lifting circuit of the hydraulic system, where the working state of the lifting circuit includes action and inaction;

[0068] S12, obtaining the working state of the steering circuit of the hydraulic system, where the working state of the steering circuit includes action and inaction;

[0069] Specifically, the hydraulic system may include a VCU (Vehicle Control Unit), an MCU (Motor Control Unit), a motor, a metering pump, a lifting valve, a lifting cylinder, a steering valve, a steering gear, a steering cylinder, and a bypass valve. Figure 2 As shown, Figure 2 The present invention discloses a working flow chart of a hydraulic system, wherein the VCU and the MCU are connected by a CAN bus, the MCU controls the rotation speed of the motor based on the communication between the VCU and the MCU, and then the motor controls the metering pump to output the required flow of hydraulic oil, the metering pump is respectively connected to the steering circuit and the lifting circuit, and is used to provide the steering circuit with the hydraulic oil of the flow required when the steering circuit is in a working state, and to provide the lifting circuit with the hydraulic oil of the flow required when the lifting circuit is in a working state, and if there is excess hydraulic oil, it will flow away through the bypass valve.

[0070] Please note that, see Figure 3 As shown, Figure 3This is a schematic diagram of a hydraulic system disclosed in the present invention. The lifting circuit of the hydraulic system includes a lifting valve and a lifting cylinder. The steering circuit of the hydraulic system includes a steering valve, a steering gear and a lifting cylinder. The working cylinder includes a steering cylinder and a lifting cylinder. The hydraulic system may also include a tilting cylinder and a tilting valve. The quantitative pump provides hydraulic oil to the tilting cylinder through the tilting valve. The tilting cylinder is used to maintain the swing of the mast. The lifting valve, the steering valve, the tilting valve and the bypass valve constitute a multi-way valve of the hydraulic system.

[0071] Specifically, the motor of the hydraulic system drives the quantitative pump to output hydraulic oil, and the output hydraulic oil enters the working cylinder through the multi-way valve to perform corresponding actions. The MCU is connected to the VCU through the CAN bus for communication to determine the working status of the lifting circuit of the hydraulic system and the working status of the steering circuit of the hydraulic system. Among them, the working status of the lifting circuit includes two working states: action and inaction, and the working status of the steering circuit also includes two working states: action and inaction.

[0072] S13. Determine the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, so as to control the motor based on the rotation speed.

[0073] In this embodiment, in order to make the motor of the hydraulic system run according to its own working requirements and reduce energy consumption, it is ensured that the hydraulic oil of the lifting circuit and the steering circuit of the hydraulic system is always sufficient in various working conditions, so as to avoid the uneven operation of the hydraulic system due to insufficient hydraulic oil. To this end, this application considers the steering working condition while considering the lifting working condition. According to the two working conditions of the lifting circuit and the two working conditions of the steering circuit, it can be determined that the hydraulic system has four working modes. The four working modes of the current hydraulic system control the motor to run at the corresponding speed, which reduces power consumption while also providing sufficient hydraulic oil for each working cylinder to ensure the smooth operation of the hydraulic system.

[0074] It should be noted that the four working modes of the hydraulic system include idle mode, steering mode, lifting mode and steering and lifting combined mode. The idle mode means that the lifting circuit is in an inactive working state and the steering circuit is in an inactive working state. The steering mode means that the lifting circuit is in an inactive working state and the steering circuit is in an active working state. The lifting mode means that the lifting circuit is in an active working state and the steering circuit is in an inactive working state. The steering and lifting combined mode means that the lifting circuit is in an active working state and the steering circuit is in an active working state.

[0075] Specifically, when the hydraulic system is in the idle mode, the motor of the hydraulic system is controlled to run at the lowest speed. Even if the metering pump will output hydraulic oil to the outside at this time, because the speed of the motor of the hydraulic system is very low, the flow of hydraulic oil consumed by the bypass valve is very small, thereby reducing the energy consumption of the hydraulic system in the idle mode; when the hydraulic system is in the steering mode / lifting mode, the motor of the hydraulic system is controlled to run according to its own steering / lifting requirements, and the metering pump will output the flow of hydraulic oil required for steering / lifting to the outside, so that the hydraulic system can operate normally; when the hydraulic system is in the steering and lifting combined mode, the steering condition and the lifting condition are considered in parallel, and the speed of the motor is associated with both the steering circuit and the lifting circuit, to ensure that the hydraulic oil is always sufficient when the lifting circuit and the steering circuit of the hydraulic system are in the working state, thereby avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil, and improving the operation efficiency of the hydraulic system.

[0076] It can be seen that the present application controls the motor to run at a corresponding speed under various working conditions of the lifting circuit and steering circuit of the hydraulic system, so that the motor operates according to its own working requirements and reduces energy consumption. At the same time, it ensures that the hydraulic oil in the lifting circuit and steering circuit of the hydraulic system is always sufficient under various working conditions, avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil, thereby improving the operating efficiency of the hydraulic system.

[0077] Based on the above embodiments:

[0078] As an optional embodiment, the hydraulic system further comprises a potentiometer, which is mounted on the lifting valve in the lifting circuit and is used to detect the displacement of the valve core of the lifting valve;

[0079] Obtain the working status of the lifting circuit of the hydraulic system, including:

[0080] Obtain the voltage signal collected by the potentiometer;

[0081] If the voltage signal is less than or equal to the preset voltage threshold, it is determined that the lifting circuit is in a non-actuating working state;

[0082] If the voltage signal is greater than the preset voltage threshold, it is determined that the lifting circuit is in an operating state.

[0083] In this embodiment, in order to provide a sufficient flow of hydraulic oil to the lifting circuit, it is necessary to first determine the working state of the lifting circuit, so as to determine the flow of hydraulic oil provided to the lifting circuit based on the working state of the lifting circuit. Since the potentiometer can convert mechanical displacement into a voltage signal, a potentiometer is installed on the lifting valve in the lifting circuit. In this way, the potentiometer can monitor the displacement of the valve core of the lifting valve in real time, and the current working state of the lifting circuit is determined by the relationship between the displacement of the valve core of the lifting valve and the voltage of the potentiometer and the control flow of the lifting circuit. Specifically, if the voltage signal of the potentiometer is less than or equal to the preset voltage threshold, the displacement of the valve core of the lifting valve of the lifting circuit is less than or equal to the preset displacement threshold, and the lifting circuit is in a non-acting working state; if the voltage signal of the potentiometer is greater than the preset voltage threshold, the displacement of the valve core of the lifting valve of the lifting circuit is greater than the preset displacement threshold, and the lifting circuit is in an acting working state. Among them, the preset displacement threshold corresponds to the preset voltage threshold of the potentiometer at this time, the displacement of the valve core of the lifting valve is positively correlated with the voltage of the potentiometer, and the relationship between the voltage of the potentiometer and the control flow of the lifting circuit can be a curve graph of the relationship between the voltage of the potentiometer and the control flow of the lifting circuit.

[0084] See also Figure 4 As shown, Figure 4 The present invention discloses a relationship curve diagram between the voltage of a potentiometer and the control flow of a lifting circuit, wherein when the voltage of the potentiometer is less than or equal to 20%, it is a dead zone of the lifting circuit. Within the dead zone, even if the valve core of the lifting valve is displaced and the potentiometer has voltage, the hydraulic oil cannot flow from the lifting valve into the lifting cylinder, and the control flow of the lifting circuit is 0; when the voltage of the potentiometer is greater than 20% and less than 40%, it is the micro-motion operation range AB of the lifting circuit. Within the micro-motion operation range AB, the voltage of the potentiometer is positively correlated with the control flow of the lifting circuit, and the critical point between the dead zone of the lifting circuit and the micro-motion operation range AB is point A; when the voltage of the potentiometer is greater than 40% and less than 80%, it is the lifting circuit. The rapid operation range BC, in which the voltage of the potentiometer is positively correlated with the control flow of the lifting circuit, and the positive correlation is greater than the positive correlation between the voltage of the potentiometer and the control flow of the lifting circuit in the micro-operation range AB, and the critical point between the micro-operation range AB and the rapid operation range BC of the lifting circuit is point B; when the voltage of the potentiometer is greater than or equal to 80%, it is the maximum operation range CD of the lifting circuit, in which the control flow of the lifting circuit remains unchanged, and at this time the control flow of the lifting circuit is the largest, the critical point between the rapid operation range BC and the maximum operation range CD of the lifting circuit is point C, and the maximum value of the maximum operation range CD is point D. Since the lifting circuit of the hydraulic system is in the working state of action, the corresponding hydraulic system has two working modes: lifting mode and steering and lifting combined mode. Correspondingly, there are also two curves of the relationship between the flow provided by the quantitative pump and the voltage of the potentiometer.

[0085] In the first specific implementation, if the hydraulic system is in the lifting mode, please refer to Figure 5 As shown, Figure 5 The graph is a relationship curve between the flow rate provided by the metering pump and the voltage of the potentiometer in a lifting mode disclosed in the present invention. When the voltage of the potentiometer is less than or equal to 20%, it is a dead zone of the lifting circuit. Within the dead zone, even if the valve core of the lifting valve is displaced and the potentiometer has voltage, the hydraulic oil cannot flow from the lifting valve into the lifting cylinder, and the control flow rate of the lifting circuit is 0, so the flow rate provided by the metering pump is also 0; when the voltage of the potentiometer is greater than 20% and less than 40%, it is the micro-operation range A'B' of the lifting circuit. In the micro-operation range A'B', the voltage of the potentiometer is positively correlated with the control flow rate of the lifting circuit. In order to ensure the controllability of fine operations, the lifting action can be slightly adjusted to enhance the sensitivity of the lifting action. Therefore, it is necessary to ensure that the metering pump provides The flow rate is greater than the control flow rate of the lifting circuit, and a small amount of excess flow flows away from the bypass valve. At this time, the critical point between the dead zone of the lifting circuit and the micro-motion operation interval A'B' is point A'; when the voltage of the potentiometer is greater than 40% and less than 80%, it is the fast operation interval B'C' of the lifting circuit. In order to ensure the energy saving of the lifting action, the flow rate provided by the metering pump needs to be less than the control flow rate of the lifting circuit to reduce energy consumption, and the voltage of the potentiometer in the fast operation interval B'C' is positively correlated with the control flow rate of the lifting circuit, and this positive correlation is greater than the positive correlation between the voltage of the potentiometer and the control flow rate of the lifting circuit in the micro-motion operation interval A'B'. The critical point between the inching operation range AB and the fast operation range BC of the lifting circuit is point B'; when the voltage of the potentiometer is greater than or equal to 80%, it is the maximum operation range C'D' of the lifting circuit. In order to ensure the energy saving of the lifting action and reduce energy consumption, the flow rate provided by the metering pump needs to be less than the control flow rate of the lifting circuit. In the maximum operation range C'D', the control flow rate of the lifting circuit remains unchanged within the voltage, and the control flow rate of the lifting circuit is the largest at this time. The critical point between the fast operation range B'C' and the maximum operation range C'D' of the lifting circuit is point C', and the maximum value of the maximum operation range C'D' is point D'. Theoretically, the flow rate provided by the metering pump remains unchanged. Due to the efficiency problem of the metering pump, full load is heavy load, and the hydraulic oil leaks more when it is heavily loaded, so the efficiency of the metering pump is low. In order to ensure that the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when it is light load is the same as the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when it is heavy load, it is necessary to make the flow rate provided by the metering pump greater than the flow rate provided by the metering pump when it is unloaded when the efficiency of the metering pump is lower, that is, when it is fully loaded. That is, the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded.

[0086] In the second specific implementation, if the hydraulic system is in the steering and lifting combined mode, please refer to Figure 6 As shown, Figure 6The present invention discloses a curve diagram of the relationship between the flow rate provided by the metering pump and the voltage of the potentiometer in a steering and lifting combined mode. When the voltage of the potentiometer is less than or equal to 20%, it is a dead zone of the lifting circuit. Within the dead zone, even if the valve core of the lifting valve is displaced and the potentiometer has voltage, the hydraulic oil cannot flow from the lifting valve into the lifting cylinder. The control flow of the lifting circuit is 0, but the maximum flow rate required for the steering mode needs to be considered. The maximum flow rate required for the steering mode is Q0, so the flow rate provided by the metering pump is also the maximum flow rate required for the steering mode. When the voltage of the potentiometer is greater than 20% and less than 40%, it is the micro-motion operation range A''B'' of the lifting circuit. In the micro-motion operation range A''B'', the voltage of the potentiometer and the lifting circuit are in a constant state. There is a positive correlation between the control flow rate and the lifting action. In order to ensure the controllability of fine operations, the lifting action can be finely adjusted to enhance the sensitivity of the lifting action. At the same time, the maximum flow rate required for the steering mode must be considered. Therefore, it is necessary to ensure that the flow rate provided by the metering pump is greater than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode. The excess small amount of flow flows away from the bypass valve. The critical point between the dead zone of the lifting circuit and the micro-motion operation range A''B'' is point A''; when the voltage of the potentiometer is greater than 40% and less than 80%, it is the fast operation range B''C'' of the lifting circuit. In order to ensure the energy saving of the lifting action, at the same time The maximum flow required for the steering mode needs to be considered. The flow provided by the metering pump needs to be smaller than the sum of the control flow of the lifting circuit and the maximum flow required for the steering mode to reduce energy consumption. In the fast operation range B''C'', the voltage of the potentiometer is positively correlated with the sum of the control flow of the lifting circuit and the maximum flow required for the steering mode. This positive correlation is greater than the positive correlation between the voltage of the potentiometer and the sum of the control flow of the lifting circuit and the maximum flow required for the steering mode in the micro-operation range A''B''. The critical value of the micro-operation range A''B'' of the lifting circuit and the fast operation range B''C'' is Point B''; when the voltage of the potentiometer is greater than or equal to 80%, it is the maximum operating range C''D'' of the lifting circuit. In order to ensure the energy-saving of the lifting action and reduce energy consumption, the flow provided by the metering pump needs to be less than the sum of the control flow of the lifting circuit and the maximum flow required by the steering mode. Within the maximum operating range C''D'' voltage, the control flow of the lifting circuit remains unchanged, and at this time the control flow of the lifting circuit is the largest. The critical point between the fast operating range B''C'' and the maximum operating range C''D'' of the lifting circuit is point C'', and the maximum value of the maximum operating range C''D'' is point D''.Theoretically, the flow rate provided by the metering pump remains unchanged. Due to the efficiency problem of the metering pump, full load is heavy load, and the hydraulic oil leaks more when it is heavily loaded, so the efficiency of the metering pump is low. In order to ensure that the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when it is light load is the same as the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when it is heavy load, it is necessary to make the flow rate provided by the metering pump greater than the flow rate provided by the metering pump when it is unloaded when the efficiency of the metering pump is lower, that is, when it is fully loaded. That is, the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded.

[0087] It can be seen that in this embodiment, a potentiometer is installed on the lifting valve in the lifting circuit. The potentiometer can be used to accurately obtain the displacement information of the valve core on the lifting valve, so as to determine the working state of the lifting circuit of the hydraulic system, which is beneficial to the subsequent flexible and precise adjustment of the motor speed based on the voltage signal, thereby ensuring the stable operation of the hydraulic system and improving the operating efficiency of the hydraulic system.

[0088] As an optional embodiment, the hydraulic system further includes a pressure sensor, which is installed at the load oil port of the steering gear in the steering circuit and is used to detect the pressure of the load at the load oil port;

[0089] Obtain the working status of the steering circuit of the hydraulic system, including:

[0090] Acquire a pressure signal collected by a pressure sensor;

[0091] If the pressure signal is less than or equal to the preset pressure threshold, it is determined that the steering circuit is in an inactive working state;

[0092] If the pressure signal is greater than the preset pressure threshold, it is determined that the steering circuit is in an actuated working state.

[0093] In this embodiment, in order to provide a sufficient flow of hydraulic oil to the steering circuit, it is necessary to first determine the working state of the steering circuit, so as to determine the flow of hydraulic oil provided to the steering circuit based on the working state of the steering circuit. Because the pressure sensor can sense the change in pressure through the metal diaphragm, when the pressure of the load of the steering gear of the steering circuit is applied to the strain gauge, the resistance value of the pressure sensor will change, and then the pressure signal will be converted into an electrical signal output. Therefore, a pressure sensor is installed at the load oil port of the steering gear in the steering circuit. The pressure sensor can monitor the pressure of the load at the load oil port in real time, and the current working state can be determined by the pressure of the load at the load oil port.

[0094] Specifically, if the pressure signal of the pressure sensor is less than or equal to the preset pressure signal threshold, the pressure of the load is small, there is no steering demand at this time, and the steering circuit is in a non-actuated working state; if the pressure signal of the pressure sensor is greater than the preset pressure signal threshold, the pressure of the load is large, there is a steering demand at this time, and the steering circuit is in an active working state. In order to ensure that the steering circuit can complete the steering action when the pressure signal of the pressure sensor is greater than any value of the preset pressure signal threshold, the maximum flow required by the steering mode can be used to provide hydraulic oil to the steering cylinder. Correspondingly, the speed of the motor at this time is the ratio of the maximum flow required by the steering mode to the unit displacement of the metering pump in the hydraulic system.

[0095] It can be seen that this embodiment installs a pressure sensor at the load oil port of the steering gear in the steering circuit, and uses the pressure sensor to monitor the load pressure of the steering circuit in real time to determine the working state of the steering circuit of the hydraulic system. When there is a steering demand, the motor is controlled to operate at the ratio of the maximum flow required by the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system, ensuring that the steering circuit can complete the steering action when the pressure signal of the pressure sensor is greater than any value of the preset pressure signal threshold, thereby improving the reliability of the hydraulic system.

[0096] As an optional embodiment, if the lifting circuit is in a non-actuating working state, and the steering circuit is in a non-actuating working state;

[0097] The speed of the motor of the hydraulic system is determined based on the working state of the lifting circuit and the working state of the steering circuit, including:

[0098] Determining that the hydraulic system is in an idle mode based on an inactive working state of a lifting circuit and an inactive working state of a steering circuit;

[0099] The rotation speed of the motor of the hydraulic system is determined to be a first rotation speed, wherein the first rotation speed is a preset minimum rotation speed, and the preset minimum rotation speed is smaller than the ratio of the maximum flow required by the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system.

[0100] In this embodiment, since the lifting circuit and the steering circuit each have two working states, it can be determined that the hydraulic system has four working modes. When the lifting circuit is in an inactive working state and the steering circuit is in an inactive working state, it can be determined that the hydraulic system is in idle mode. At this time, the hydraulic system has neither steering demand nor lifting demand. However, in order to maintain the basic operation of the hydraulic system and to quickly meet the operating requirements when the hydraulic system has steering demand and / or lifting demand, it is necessary to control the motor at a first speed, wherein the first speed is a preset minimum speed.

[0101] In order to further reduce the energy consumption when the hydraulic system is in idle mode, the motor speed when the hydraulic system is in idle mode needs to be lower than the motor speed when the hydraulic system is in steering mode, so as to reduce the loss of hydraulic oil passing through the bypass valve. Since the motor speed when the hydraulic system is in steering mode is the ratio of the maximum flow required for the steering mode to the unit displacement of the metering pump in the hydraulic system, the preset minimum speed is lower than the ratio of the maximum flow required for the steering mode divided by the unit displacement of the metering pump in the hydraulic system. Among them, the maximum flow required for the steering mode is the flow of hydraulic oil required when the hydraulic system has the maximum steering demand.

[0102] It can be seen that in this embodiment, when the hydraulic system is in the idle mode, the motor is controlled to run at a lower speed, thereby reducing the loss of hydraulic oil passing through the bypass valve.

[0103] As an optional embodiment, if the lifting circuit is in a non-actuated working state, and the steering circuit is in an acted working state;

[0104] The speed of the motor of the hydraulic system is determined based on the working state of the lifting circuit and the working state of the steering circuit, including:

[0105] Determining that the hydraulic system is in a steering mode based on an inactive working state of the lifting circuit and an active working state of the steering circuit;

[0106] The rotation speed of the motor of the hydraulic system is determined to be a second rotation speed, wherein the second rotation speed is a ratio of a maximum flow required by the steering mode to a unit displacement of the fixed displacement pump.

[0107] In this embodiment, since the lifting circuit and the steering circuit each have two working states, it can be determined that the hydraulic system has four working modes. When the lifting circuit is in a non-actuated working state and the steering circuit is in an actuated working state, it can be determined that the hydraulic system is in a steering mode. At this time, the hydraulic system only has a steering demand and no lifting demand. However, in order to ensure that the steering circuit can complete the steering action under different steering demands, the maximum flow required by the steering mode can be used to provide hydraulic oil to the steering cylinder. Correspondingly, the speed of the motor at this time is the second speed, and the second speed is the ratio of the maximum flow required by the steering mode to the unit displacement of the metering pump in the hydraulic system. Among them, the maximum flow required by the steering mode is the flow of the maximum steering demand of the steering mode, and different steering demands are different angles that the steering circuit needs to complete the steering. The flow of the maximum steering demand of the steering mode is the maximum angle that the steering circuit needs to complete the steering.

[0108] It can be seen that in this embodiment, when the hydraulic system is in the steering mode, the control motor runs at a speed corresponding to the flow rate of the maximum steering requirement of the steering mode, ensuring that the steering circuit can complete the steering action under different steering requirements, thereby improving the reliability of the hydraulic system operation.

[0109] As an optional embodiment, if the lifting circuit is in an actuated working state, and the steering circuit is in an inactive working state;

[0110] The speed of the motor of the hydraulic system is determined based on the working state of the lifting circuit and the working state of the steering circuit, including:

[0111] Determining that the hydraulic system is in a lifting mode based on the lifting circuit being in an actuated working state and the steering circuit being in an inactive working state;

[0112] Determine the control flow of the hoisting circuit;

[0113] If the lifting circuit is in the inching operation range A'B', it is determined that the flow rate provided by the metering pump in the hydraulic system is greater than the control flow rate of the lifting circuit;

[0114] If the lifting circuit is in the fast operation interval B'C', it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, wherein when the lifting circuit is at the critical point of the inching operation interval A'B' and the fast operation interval B'C', the flow rate provided by the metering pump in the hydraulic system is equal to the control flow rate of the lifting circuit when the lifting circuit is at the critical point of the inching operation interval A'B' and the fast operation interval B'C';

[0115] If the lifting circuit is in the maximum operating range C'D', it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range C'D';

[0116] Determine the ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump, and use the ratio as the speed of the motor of the hydraulic system.

[0117] In this embodiment, since the lifting circuit and the steering circuit each have two working states, it can be determined that the hydraulic system has four working modes. When the lifting circuit is in an actuated working state and the steering circuit is in an inactive working state, it can be determined that the hydraulic system is in a lifting mode. At this time, the hydraulic system only has a lifting demand and no steering demand. However, in order to ensure that the lifting circuit can dynamically adjust the motor speed according to the demand under different lifting demands, the energy consumption of the hydraulic system is reduced. When the lifting circuit is in an actuated working state, the lifting circuit can be divided into three operating intervals according to different lifting demands. The three operating intervals include the micro-motion operating interval A'B', the fast operating interval B'C' and the maximum operating interval C'D'. Based on the three operating intervals of the lifting circuit, the motor is controlled to run at different speeds.

[0118] Specifically, when the lifting circuit is in the micro-motion operation range A'B', in order to ensure the controllability of fine operations, the lifting action can be slightly adjusted to enhance the sensitivity of the lifting action. Therefore, it is necessary to ensure that the flow rate provided by the metering pump is greater than the control flow rate of the lifting circuit, and the excess small amount of flow flows away from the bypass valve; when the lifting circuit is in the fast operation range B'C', in order to ensure the energy saving of the lifting action, the flow rate provided by the metering pump needs to be less than the control flow rate of the lifting circuit to reduce energy consumption. When the lifting circuit is at the critical point between the micro-motion operation range A'B' and the fast operation range B'C', the flow rate provided by the metering pump needs to be equal to the control flow rate of the lifting circuit; when the lifting circuit is in the maximum operation range C'D' In order to ensure the energy saving of the lifting action and reduce energy consumption, the flow rate provided by the metering pump needs to be less than the control flow rate of the lifting circuit. At this time, the control flow rate of the lifting circuit remains unchanged. In theory, the flow rate provided by the metering pump also remains unchanged. Due to the efficiency problem of the metering pump, full load is heavy load, and the hydraulic oil leaks more when it is heavy load. The efficiency of the metering pump is low. In order to ensure that the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when light load is the same as the flow rate of hydraulic oil provided to the steering circuit and the lifting circuit when heavy load is provided, it is necessary to make the flow rate provided by the metering pump greater than the flow rate provided by the metering pump when no load is provided when the efficiency of the metering pump is low, that is, when it is full load, that is, when the lifting circuit is fully loaded, the flow rate provided by the metering pump in the hydraulic system is the largest. Then determine the ratio of the flow rate provided by the metering pump in the hydraulic system divided by the unit displacement of the metering pump, and use the ratio as the speed of the motor of the hydraulic system.

[0119] It can be seen that this embodiment controls the motor to run at a corresponding speed when the lifting circuit is in different operating ranges, which reduces energy consumption while also taking into account the requirements of different operating ranges of the lifting circuit, thereby enhancing the reliability of the hydraulic system.

[0120] As an optional embodiment, if the lifting circuit is in an actuated working state, and the steering circuit is in an actuated working state;

[0121] The speed of the motor of the hydraulic system is determined based on the working state of the lifting circuit and the working state of the steering circuit, including:

[0122] Determining that the hydraulic system is in a steering and lifting combined mode based on the working state of the lifting circuit being in action and the working state of the steering circuit being in action;

[0123] Determine the control flow of the hoisting circuit;

[0124] If the lifting circuit is in the inching operation range A''B'', it is determined that the flow rate provided by the metering pump in the hydraulic system is greater than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode;

[0125] If the lifting circuit is in the fast operation interval B''C'', it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode, wherein, when the lifting circuit is at the critical point between the inching operation interval A''B'' and the fast operation interval B''C'', the flow rate provided by the metering pump in the hydraulic system is equal to the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode when the lifting circuit is at the critical point between the inching operation interval A''B'' and the fast operation interval B''C'';

[0126] If the lifting circuit is in the maximum operating range C''D'', it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range C''D'';

[0127] Determine the ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump, and use the ratio as the speed of the motor of the hydraulic system.

[0128] In this embodiment, since the lifting circuit and the steering circuit each have two working states, it can be determined that the hydraulic system has four working modes. When the lifting circuit is in an actuated working state and the steering circuit is in an actuated working state, it can be determined that the hydraulic system is in a steering and lifting combined mode. In order to ensure that when the hydraulic system is in a steering and lifting combined mode, the steering cylinder of the steering circuit and the lifting cylinder of the lifting circuit both have sufficient hydraulic oil to support the steering action and the lifting action, and the hydraulic system can run smoothly, the steering condition is considered in parallel with the lifting condition. Specifically, the needs of the steering circuit are taken into consideration in various action ranges of the lifting circuit under lifting conditions. While ensuring that the lifting circuit can dynamically adjust the speed of the motor as required when the lifting circuit has different lifting needs, the maximum flow required for the steering mode is added to the flow of hydraulic oil required in the three operating ranges of the lifting circuit. Accordingly, the hydraulic system is also divided into three operating ranges in the case of the combined steering and lifting mode. The three operating ranges include the inching operating range A''B'', the fast operating range B''C'' and the maximum operating range C''D''. The motor is controlled to run at different speeds based on the three operating ranges of the hydraulic system.

[0129] Specifically, when the lifting circuit is in the micro-motion operation range A''B'', in order to ensure the controllability and steering requirements of the fine operation of the lifting circuit, the lifting action can be finely adjusted to enhance the sensitivity of the lifting action. Therefore, it is necessary to ensure that the flow rate provided by the metering pump is greater than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode, and the excess small amount of flow flows away from the bypass valve; when the lifting circuit is in the fast operation range B''C'', in order to ensure the energy saving and steering requirements of the lifting action, the flow rate provided by the metering pump needs to be less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode to reduce energy consumption. When the lifting circuit is at the critical point between the micro-motion operation range A''B'' and the fast operation range B''C'', the flow rate provided by the metering pump needs to be equal to the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode The sum of the flow rates; when the lifting circuit is in the maximum operating range C''D'', in order to ensure the energy saving and steering requirements of the lifting action and reduce energy consumption, the flow rate provided by the metering pump needs to be less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode. At this time, the control flow rate of the lifting circuit remains unchanged. In theory, the flow rate provided by the metering pump also remains unchanged. Due to the efficiency problem of the metering pump, full load is heavy load, and the hydraulic oil leaks more when it is heavy, and the efficiency of the metering pump is low. In order to ensure that the flow rate of the hydraulic oil provided to the steering circuit and the lifting circuit when light load is the same as the flow rate of the hydraulic oil provided to the steering circuit and the lifting circuit when heavy load is provided, it is necessary to make the flow rate provided by the metering pump greater than the flow rate provided by the metering pump when no load is provided when the efficiency of the metering pump is low, that is, when it is full load, that is, when the lifting circuit is full load, the flow rate provided by the metering pump in the hydraulic system is the largest. Then determine the ratio of the flow rate provided by the metering pump in the hydraulic system divided by the unit displacement of the metering pump, and use the ratio as the speed of the motor of the hydraulic system.

[0130] It can be seen that this embodiment takes into account the lifting requirements of the lifting circuit in different operating ranges and the steering requirements of the steering circuit in parallel. The maximum flow required by the steering mode is added to the flow of hydraulic oil required in various operating ranges of the lifting circuit, and the motor operation is controlled at the corresponding speed. While reducing energy consumption, it ensures that the lifting circuit and steering circuit of the hydraulic system always have sufficient hydraulic oil in various working conditions, thereby improving the operating efficiency of the hydraulic system.

[0131] The present invention further provides a forklift, comprising a hydraulic system and an electric forklift energy-saving control device as described above, wherein the electric forklift energy-saving control device is connected to the hydraulic system.

[0132] It should be noted that the hydraulic system includes VCU, MCU, motor, fixed displacement pump, lifting valve, lifting cylinder, steering valve, steering gear, steering cylinder and bypass valve. The VCU and MCU are connected by CAN bus, and the MCU controls the speed of the motor based on the communication between the VCU and MCU. Figure 7 As shown, Figure 7 The present invention discloses a flow chart of a specific electric forklift energy-saving control method.

[0133] In addition, the introduction of a forklift provided by the invention can be referred to the embodiment of the energy-saving control method of the electric forklift, and the invention will not be repeated here.

[0134] It can be seen that the forklift of the present application controls the motor to run at a corresponding speed under various working conditions of the lifting circuit and steering circuit of the hydraulic system, so that the motor operates according to its own working requirements and reduces energy consumption. At the same time, it ensures that the hydraulic oil in the lifting circuit and steering circuit of the hydraulic system is always sufficient under various working conditions, avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil, thereby improving the operating efficiency of the hydraulic system.

[0135] Accordingly, see Figure 8 As shown, Figure 8 The present invention also provides an energy-saving control system for an electric forklift, including:

[0136] A first acquisition module 31 is used to acquire the working state of a lifting circuit of a hydraulic system, wherein the working state of the lifting circuit includes action and inaction;

[0137] A second acquisition module 32 is used to acquire the working state of the steering circuit of the hydraulic system, where the working state of the steering circuit includes action and inaction;

[0138] The determination module 33 is used to determine the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, so as to control the motor based on the rotation speed.

[0139] It can be seen that the present application controls the motor to run at a corresponding speed under various working conditions of the lifting circuit and steering circuit of the hydraulic system, so that the motor operates according to its own working requirements and reduces energy consumption. At the same time, it ensures that the hydraulic oil in the lifting circuit and steering circuit of the hydraulic system is always sufficient under various working conditions, avoiding the problem of uneven operation of the hydraulic system caused by insufficient hydraulic oil, thereby improving the operating efficiency of the hydraulic system.

[0140] In some specific embodiments, the hydraulic system further comprises a potentiometer, which is mounted on a lifting valve in the lifting circuit and is used to detect the displacement of a valve core of the lifting valve;

[0141] The first acquisition module 31 includes:

[0142] A first acquisition unit, used to acquire the voltage signal collected by the potentiometer;

[0143] A first determination unit, configured to determine that the hoisting circuit is in a non-actuating working state if the voltage signal is less than or equal to a preset voltage threshold;

[0144] The second determination unit is used to determine that the lifting circuit is in an operating state if the voltage signal is greater than a preset voltage threshold.

[0145] In some specific embodiments, the hydraulic system further includes a pressure sensor, which is installed at a load oil port of a steering gear in the steering circuit and is used to detect the pressure of a load at the load oil port;

[0146] The second acquisition module 32 includes:

[0147] A second acquisition unit, used to acquire the pressure signal collected by the pressure sensor;

[0148] a third determination unit, configured to determine that the steering circuit is in an inoperative working state if the pressure signal is less than or equal to a preset pressure threshold;

[0149] The fourth determination unit is configured to determine that the steering circuit is in an actuating working state if the pressure signal is greater than a preset pressure threshold.

[0150] In some specific embodiments, if the lifting circuit is in a non-actuated working state, and the steering circuit is in a non-actuated working state;

[0151] The determination module 33 comprises:

[0152] a first determining unit, configured to determine that the hydraulic system is in an idle mode based on an inactive working state of the lifting circuit and an inactive working state of the steering circuit;

[0153] The second determination unit is used to determine that the speed of the motor of the hydraulic system is a first speed, wherein the first speed is a preset minimum speed, and the preset minimum speed is smaller than the ratio of the maximum flow required by the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system.

[0154] In some specific embodiments, if the lifting circuit is in a non-actuated working state, and the steering circuit is in an acted working state;

[0155] The determination module 33 comprises:

[0156] a third determining unit, configured to determine that the hydraulic system is in a steering mode based on an inactive working state of the lifting circuit and an active working state of the steering circuit;

[0157] The fourth determination unit is used to determine that the rotation speed of the motor of the hydraulic system is a second rotation speed, wherein the second rotation speed is a ratio of a maximum flow required by a steering mode to a unit displacement of a fixed displacement pump.

[0158] In some specific embodiments, if the lifting circuit is in an actuated working state, and the steering circuit is in an inactive working state;

[0159] The determination module 33 comprises:

[0160] a fifth determining unit, configured to determine that the hydraulic system is in a lifting mode based on the lifting circuit being in an actuated working state and the steering circuit being in an inactive working state;

[0161] A sixth determining unit, configured to determine a control flow rate of the hoisting circuit;

[0162] a seventh determination unit, configured to determine that a flow rate provided by a metering pump in the hydraulic system is greater than a control flow rate of the lifting circuit if the lifting circuit is in an inching operation range;

[0163] an eighth determination unit, for determining, if the lifting circuit is in a fast operation range, that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, wherein, when the lifting circuit is at a critical point between the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the control flow rate of the lifting circuit when the lifting circuit is at a critical point between the inching operation range and the fast operation range;

[0164] a ninth determining unit, for determining, if the lifting circuit is in the maximum operating range, that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, and that the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and that the control flow rate of the lifting circuit remains unchanged in the maximum operating range;

[0165] The tenth determining unit is used to determine the ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump, and use the ratio as the rotation speed of the motor of the hydraulic system.

[0166] In some specific embodiments, if the lifting circuit is in an actuated working state, and the steering circuit is in an actuated working state;

[0167] The determination module 33 comprises:

[0168] an eleventh determining unit, configured to determine that the hydraulic system is in a steering and lifting combined mode based on the working state that the lifting circuit is in an action state and the working state that the steering circuit is in an action state;

[0169] a twelfth determining unit, configured to determine a control flow rate of the lifting circuit;

[0170] a thirteenth determining unit, configured to determine, if the lifting circuit is in the inching operation range, that a flow rate provided by the metering pump in the hydraulic system is greater than a sum of a control flow rate of the lifting circuit and a maximum flow rate required by a steering mode;

[0171] A fourteenth determining unit is used to determine that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode if the lifting circuit is in the fast operation range, wherein when the lifting circuit is at the critical point of the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode when the lifting circuit is at the critical point of the inching operation range and the fast operation range;

[0172] A fifteenth determining unit is used to determine that if the lifting circuit is in the maximum operating range, the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range;

[0173] The sixteenth determination unit is used to determine the ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump, and use the ratio as the rotation speed of the motor of the hydraulic system.

[0174] Furthermore, the present application also discloses an electronic device. Fig. 9 This is a structural diagram of an electronic device disclosed in the present invention. The content in the diagram cannot be regarded as any limitation on the scope of use of this application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the energy-saving control method for an electric forklift disclosed in any of the aforementioned embodiments. In addition, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0175] In this embodiment, the power supply 23 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and the external device, and the communication protocol it follows is any communication protocol that can be applied to the technical solution of the present application, and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0176] In addition, the memory 22, as a carrier for storing resources, can be a read-only memory, a random access memory, a disk or an optical disk, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0177] The operating system 221 is used to manage and control the hardware devices and computer programs 222 on the electronic device 20, and can be Windows, Server, Netware, Unix, Linux, etc. In addition to the computer program that can be used to complete the electric forklift energy-saving control method executed by the electronic device 20 disclosed in any of the aforementioned embodiments, the computer program 222 can further include computer programs that can be used to complete other specific tasks.

[0178] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0179] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0180] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy-saving control method for an electric forklift, characterized in that: include: Acquire the working state of the lifting circuit of the hydraulic system, wherein the working state of the lifting circuit includes action and inaction; Acquiring the working state of the steering circuit of the hydraulic system, wherein the working state of the steering circuit includes action and inaction; Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, so as to control the motor based on the rotation speed; Among them, if the lifting circuit is in an inoperative working state, and the steering circuit is in an inoperative working state; determining the speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit, including: determining that the hydraulic system is in idle mode based on the inoperative working state of the lifting circuit and the inoperative working state of the steering circuit; determining that the speed of the motor of the hydraulic system is a first speed, wherein the first speed is a preset minimum speed, and the preset minimum speed is less than the ratio of the maximum flow required for the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system.

2. The energy-saving control method for an electric forklift according to claim 1, characterized in that: The hydraulic system further comprises a potentiometer, which is mounted on a lifting valve in the lifting circuit and is used to detect the displacement of a valve core of the lifting valve; Obtain the working status of the lifting circuit of the hydraulic system, including: Acquiring a voltage signal collected by the potentiometer; If the voltage signal is less than or equal to a preset voltage threshold, it is determined that the lifting circuit is in a non-actuating working state; If the voltage signal is greater than a preset voltage threshold, it is determined that the lifting circuit is in an operating state.

3. The energy-saving control method for an electric forklift according to claim 1, characterized in that: The hydraulic system further comprises a pressure sensor, which is installed at a load oil port of the steering gear in the steering circuit and is used to detect the pressure of the load at the load oil port; Obtaining the working state of the steering circuit of the hydraulic system includes: Acquiring a pressure signal collected by the pressure sensor; If the pressure signal is less than or equal to a preset pressure threshold, it is determined that the steering circuit is in an inactive working state; If the pressure signal is greater than a preset pressure threshold, it is determined that the steering circuit is in an actuated working state.

4. The energy-saving control method for an electric forklift according to claim 1, characterized in that: If the lifting circuit is in a non-actuated working state, and the steering circuit is in an acted working state; Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes: Determining that the hydraulic system is in a steering mode based on the inactive working state of the lifting circuit and the active working state of the steering circuit; The rotation speed of the motor of the hydraulic system is determined to be a second rotation speed, wherein the second rotation speed is a ratio of a maximum flow required for a steering mode to a unit displacement of a fixed displacement pump.

5. The energy-saving control method for an electric forklift according to claim 1, characterized in that: If the lifting circuit is in an actuated working state, and the steering circuit is in an inactive working state; Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes: Determining that the hydraulic system is in a lifting mode based on the lifting circuit being in an actuated working state and the steering circuit being in an inactive working state; determining a control flow rate of the hoisting circuit; If the lifting circuit is in the micro-motion operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is greater than the control flow rate of the lifting circuit; If the lifting circuit is in the fast operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, wherein, when the lifting circuit is at the critical point between the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the control flow rate of the lifting circuit when the lifting circuit is at the critical point between the inching operation range and the fast operation range; If the lifting circuit is in the maximum operating range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the control flow rate of the lifting circuit, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range; The ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump is determined, and the ratio is used as the rotation speed of the motor of the hydraulic system.

6. The energy-saving control method for an electric forklift according to claim 1, characterized in that: If the lifting circuit is in an actuated working state, and the steering circuit is in an actuated working state; Determining the rotation speed of the motor of the hydraulic system based on the working state of the lifting circuit and the working state of the steering circuit includes: Determining that the hydraulic system is in a steering and lifting combined mode based on the working state that the lifting circuit is in an actuated working state and the working state that the steering circuit is in an actuated working state; determining a control flow rate of the hoisting circuit; If the lifting circuit is in the inching operation range, determining that the flow rate provided by the metering pump in the hydraulic system is greater than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode; If the lifting circuit is in the fast operation range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode, wherein, when the lifting circuit is at the critical point between the inching operation range and the fast operation range, the flow rate provided by the metering pump in the hydraulic system is equal to the sum of the control flow rate of the lifting circuit and the maximum flow rate required for the steering mode when the lifting circuit is at the critical point between the inching operation range and the fast operation range; If the lifting circuit is in the maximum operating range, it is determined that the flow rate provided by the metering pump in the hydraulic system is less than the sum of the control flow rate of the lifting circuit and the maximum flow rate required by the steering mode, and the flow rate provided by the metering pump in the hydraulic system is the largest when the lifting circuit is fully loaded, and the control flow rate of the lifting circuit remains unchanged in the maximum operating range; The ratio of the flow rate provided by the metering pump in the hydraulic system to the unit displacement of the metering pump is determined, and the ratio is used as the rotation speed of the motor of the hydraulic system.

7. An energy-saving control system for an electric forklift, characterized in that: include: A first acquisition module is used to acquire the working state of a lifting circuit of a hydraulic system, wherein the working state of the lifting circuit includes action and inaction; A second acquisition module is used to acquire the working state of the steering circuit of the hydraulic system, where the working state of the steering circuit includes action and inaction; a determination module, configured to determine a rotation speed of a motor of the hydraulic system based on a working state of the lifting circuit and a working state of the steering circuit, so as to control the motor based on the rotation speed; Among them, if the lifting circuit is in an inactive working state, and the steering circuit is in an inactive working state; the determination module is specifically used to: determine that the hydraulic system is in idle mode based on the inactive working state of the lifting circuit and the inactive working state of the steering circuit; determine that the speed of the motor of the hydraulic system is a first speed, wherein the first speed is a preset minimum speed, and the preset minimum speed is less than the ratio of the maximum flow required for the steering mode to the unit displacement of the fixed displacement pump in the hydraulic system.

8. An energy-saving control device for an electric forklift, characterized in that: include: Memory, used to store computer programs; A processor is used to execute the computer program to implement the steps of the electric forklift energy-saving control method according to any one of claims 1 to 6.

9. A forklift, characterized in that: It comprises a hydraulic system and an energy-saving control device for an electric forklift as claimed in claim 8, wherein the energy-saving control device for an electric forklift is connected to the hydraulic system.

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