Control method of forklift for lowering yacht

Abstract

The invention discloses a control method of a forklift for lowering a yacht. The forklift comprises a forklift body, an executing mechanism with a plurality of lifting oil cylinders, a fork arm and an oil outlet channel. The executing mechanism drives the fork arm to move up and down through the lifting oil cylinders. The lifting oil cylinder discharges oil to the oil outlet channel, so that the fork arm moves downwards; speed limiting valves and electromagnetic flow meters are arranged at the respective connecting ends of the lifting oil cylinders and the oil outlet channel; the electromagnetic flowmeter monitors the flow of the speed limiting valve in real time; the speed limiting valves are arranged in parallel and are uniformly controlled by a control unit; and by arranging the speed limiting valve, the oil discharging flow is effectively limited, the situation that an oil outlet channel is damaged and impacts the yacht is avoided, and the operation safety is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application is a control method applied to a forklift for yacht lowering, belonging to the field of forklifts. BACKGROUND

[0002] In the process of yacht lowering, the traditional forklift technology faces many challenges.

[0003] The existing forklift mainly relies on the experience of the operator to control the lowering speed and landing force of the fork arm when performing the task of lowering heavy loads such as yachts. This operation method has great uncertainty and safety hazards.

[0004] Specifically, in the process of lowering the yacht, the traditional forklift cannot accurately control the oil discharge speed of the lifting cylinder, which may cause the oil discharge channel of the lifting cylinder to break and the yacht to be impacted, which will cause physical damage to the high-priced yacht.

[0005] Especially when dealing with heavy yachts, the traditional method is not up to the task and cannot meet the needs of actual application.

[0006] Therefore, it is of great significance to develop a forklift control method that can accurately control the lowering speed of the fork arm and achieve buffer landing, in order to improve the safety and efficiency of yacht lowering operations. SUMMARY

[0007] In view of the deficiencies of the prior art, the application aims to provide a control method for a forklift for yacht lowering to solve the problem.

[0008] In order to achieve the above-mentioned purpose, the application is implemented by the following technical solution: a control method applied to a forklift for yacht lowering, the forklift comprising a vehicle body, an actuator comprising a plurality of lifting cylinders, a fork arm, and an oil outlet passage; the actuator drives the fork arm to move up and down through the plurality of lifting cylinders; the lifting cylinder moves the fork arm downward by discharging oil to the oil outlet passage; the connection end of each of the plurality of lifting cylinders and the oil outlet passage is provided with a flow limiting valve and an electromagnetic flow meter; the electromagnetic flow meter monitors the flow of the flow limiting valve in real time; each flow limiting valve is connected in parallel and is uniformly controlled by a control unit. The control method comprises the following steps: Step 1: lower the fork arm after opening the throttle opening of the flow limiting valve to the maximum, and collect the real-time flow of the flow limiting valve through the electromagnetic flow meter, and transmit the real-time flow information to the control unit; Step 2: define a first flow threshold; when the real-time flow is less than the first flow threshold, the control unit determines that the yacht enters the initial water state; Step three: when the control unit confirms that the yacht enters the initial water state, the control unit sends an electrical signal to the speed limiting valve to adjust the orifice opening of the speed limiting valve to the minimum to limit the oil flow, so as to realize the buffer landing of the yacht; Step four: defining a second flow threshold value; if the control unit detects that the real-time flow is less than the second flow threshold value, the control unit judges that the yacht enters the complete water state; Step five: when the control unit confirms that the yacht enters the complete water state, the control unit sends an electrical signal to the speed limiting valve to adjust the orifice opening of the speed limiting valve to the maximum to increase the oil flow, so as to realize the rapid separation of the fork arm and the yacht.

[0009] Preferably, the speed limiting valve is a stepless electromagnetic valve.

[0010] Preferably, the electromagnetic flowmeter is installed downstream of the speed limiting valve.

[0011] Preferably, the control unit is manually turned on by the driver.

[0012] Preferably, the rated maximum oil output after the orifice opening of the speed limiting valve is defined to the maximum is the first flow, and the definition range of the first flow threshold value is 90% to 80% of the first flow.

[0013] Preferably, the rated maximum oil output after the orifice opening of the speed limiting valve is defined to the minimum is the second flow, and the setting range of the second flow threshold value is 90% to 80% of the second flow.

[0014] Preferably, the control unit records the flow data of the electromagnetic flowmeter at a frequency of 50Hz to 100Hz to form sampling points, and takes the average value of the latest 10 to 15 sampling points as the real-time flow.

[0015] Advantages The application effectively limits the oil flow by setting the speed limiting valve, avoids the damage of the oil outlet channel, avoids the impact on the yacht, and significantly improves the safety of the operation; by monitoring the real-time flow of the speed limiting valve in real time and making a double judgment based on the set first flow threshold value and the second flow threshold value, the entry of the yacht into the water and the entry of the yacht into the complete water can be determined. BRIEF DESCRIPTION OF DRAWINGS

[0016] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments, which should be read in conjunction with the accompanying drawings: Figure 1 It is a structural schematic view of a fork truck applied to the lowering of a yacht; Figure 2 It is a structural schematic view of a control unit. DETAILED DESCRIPTION

[0017] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in conjunction with specific embodiments.

[0018] Please refer to Figure 1 , Figure 2 The present application provides a control method of a forklift applied to yacht lowering, which comprises a vehicle body 1, an actuator 2 with a plurality of lifting cylinders 21, a fork arm 3, and an oil outlet passage; the actuator 2 drives the fork arm 3 to move up and down through the plurality of lifting cylinders 21; the lifting cylinders 21 move the fork arm 3 downward by discharging oil to the oil outlet passage; The connecting ends of the plurality of lifting cylinders 21 and the oil outlet passage are each provided with a speed limiting valve 41 and an electromagnetic flowmeter 42; the electromagnetic flowmeter 42 monitors the flow of the speed limiting valve 41 in real time; each speed limiting valve 41 is connected in parallel and is uniformly controlled by a control unit 5.

[0019] Further, the speed limiting valve 41 is a stepless electromagnetic valve to realize stepless adjustment of the opening of the speed limiting valve 41 and improve the accuracy of flow rate.

[0020] Further, the speed limiting valves 41 are connected in parallel, so that each speed limiting valve 41 operates independently, and thus when a speed limiting valve 41 or an electromagnetic flowmeter 42 is damaged, it only needs to be repaired or replaced accordingly; Further, the plurality of speed limiting valves 41 are uniformly controlled by the control unit 5, which improves the synchronization of the oil discharge of the plurality of lifting cylinders 21 and avoids the impact on the workpiece 7 (yacht) caused by the pressure change of the oil outlet passage of some lifting cylinders 21 after being damaged; wherein the control unit 5 is manually turned on by the driver, so that when heavy load working conditions (lowering the yacht) are performed, the speed limiting valve 41 can be manually opened to avoid damage caused by excessive pressure of the oil outlet passage, which causes the workpiece 7 to be impacted.

[0021] The control method comprises the following steps: Step one: define the rated maximum oil discharge after the maximum opening of the throttle opening of the speed limiting valve 41 as the first flow rate; after the maximum opening of the throttle opening of the speed limiting valve 41, the actuator 2 lowers the fork arm 3, collects the real-time flow of the speed limiting valve 41 through the electromagnetic flowmeter 42, and transmits the real-time flow information to the control unit 5; Step two: define a first flow threshold; when the real-time flow is less than the first flow threshold, the control unit 5 determines that the yacht enters the initial water state; Step three: when the control unit 5 confirms that the yacht enters the initial water state, the control unit sends an electrical signal to the limiting valve 41 to adjust the throttling opening of the limiting valve 41 to the minimum to limit the oil flow, so as to realize the buffer landing of the yacht; and the rated maximum oil output after the throttling opening of the limiting valve 41 is defined to the minimum is defined as the second flow; Step four: defining a second flow threshold; if the control unit 5 detects that the real-time flow is less than the second flow threshold, the control unit 5 judges that the yacht enters the complete water state; Step five: when the control unit 5 confirms that the yacht enters the complete water state, the control unit 5 sends an electrical signal to the limiting valve 41 to adjust the throttling opening of the limiting valve 41 to the maximum to increase the oil flow, so as to realize the rapid separation of the fork arm 3 and the yacht.

[0022] In step one, by installing the electromagnetic flowmeter 42 downstream of the limiting valve 41, the electromagnetic flowmeter 42 can accurately collect the oil flow rate of the limiting valve 41. The control unit 5 records the flow data of the electromagnetic flowmeter 42 (preferably, the accuracy of the electromagnetic flowmeter 42 is ≥±1%FS, and the response time is ≤50ms) at a frequency of 50Hz~100Hz to form a sampling point, high-frequency sampling is adopted to avoid missing the flow rate mutation; and the average value of the last 10~15 sampling points is taken as the real-time flow, so that the data acquisition is more smooth, and the accurate real-time flow is obtained to provide stable input for the control unit 5. Wherein, the electromagnetic flowmeter 42 and the limiting valve 41 are electrically connected with the control unit 5.

[0023] In step two, the first flow threshold is used to judge that the yacht enters the initial water state. According to experimental test, if the first flow threshold is set too high (such as greater than 90% of the first flow), the sensitivity of the control unit 5 to the real-time flow change will be too high, which will cause the control unit 5 to start the buffer landing of the yacht in advance due to the change of the real-time flow caused by external factors; on the contrary, if it is too low, the sensitivity to the real-time flow change will be reduced, which may cause the yacht to be too deep but not trigger the buffer landing control. Therefore, the definition range of the first flow threshold is 90%~80% of the first flow, so as to ensure that the control unit 5 will not trigger the buffer landing control due to external factors.

[0024] In step four, the second flow threshold is a key parameter to balance safety and efficiency, which is set to analyze the difference of real-time flow changes between the initial water entry state and the full water entry state of the yacht, to ensure that the second flow threshold can clearly distinguish the two states. During the lowering process of the yacht, when the yacht enters the full water entry state, the oil discharge speed of the speed limiting valve 41 will show a nonlinear decay due to the change of load (the balance of yacht gravity and buoyancy). Through experimental testing, the fork arm 3 usually descends at a constant speed during the normal descent stage, and the real-time flow changes little. During this period, the real-time flow is greater than the first flow threshold, while the yacht enters the initial water entry state, the throttle opening of the speed limiting valve has been adjusted to the minimum due to the increase of water resistance and the triggering of the buffer landing control, and the real-time flow will be less than the first flow threshold. If the second flow threshold is set too high, the control unit 5 may misjudge the normal fluctuation as a signal to step five; if it is set too low, it may cause delay in judging the yacht entering the full water entry state. Therefore, defining the second flow threshold range as 90%~80% of the second flow (defining the rated maximum oil discharge after the throttle opening of the speed limiting valve is adjusted to the minimum as the second flow), can accurately cover the flow decay characteristics of the yacht entering the full water entry state.

[0025] It is worth mentioning that through the combination of the first re-judgment (step two) and the second re-judgment (step four), a double confirmation is formed, which can determine the position of the yacht relying on the real-time flow information of the speed limiting valve 41.

[0026] Embodiment 1 The weight range of the lowered yacht is 10 tons.

[0027] Actuator 2: 6 lifting cylinders 21, symmetrically arranged on both sides of the fork arm 3; Speed limiting valve 41: stepless solenoid valve (response time ≤20ms, first flow 30L / min, second flow 4L / min) installed at the connection end of each lifting cylinder 21 and the oil outlet channel; Electromagnetic flowmeter 42: accuracy ±1%FS, response time ≤30ms, installed downstream of the speed limiting valve 41; Control unit 5: industrial-grade PLC, sampling frequency 100Hz, connected to the electromagnetic flowmeter 42 and the speed limiting valve 41 through CAN bus; Driver operation platform: equipped with manual control unit 5 start button and status indicator light.

[0028] The control method includes the following steps: Step one: control the throttle opening of the speed limiting valve 41 to the maximum; the control unit 5 records the data of the electromagnetic flowmeter 42 at a frequency of 100Hz to form a sampling point; Take the average value of the last 10 sampling points as the real-time flow, (in this embodiment, the sampling point flow rate of a certain period is [28, 29, 29,..., 28] L / min, and the last statistical average value is 29 L / min); Step two: define the first flow threshold, that is, the first flow threshold = 30 L / min x 90% = 27 L / min; when the real-time flow is 25 L / min after a certain time, that is, the real-time flow 25 L / min is less than the first flow threshold 27 L / min, the control unit 5 judges that the yacht enters the initial water state, and triggers the yellow flashing of the indicator light.

[0029] Step three: when the control unit 5 confirms that the yacht enters the initial water state, the control unit 5 sends an electrical signal to the speed limiting valve 41, adjusts the opening degree of the throttle port of the speed limiting valve 41 to the minimum, to limit the oil flow, and realizes the buffer landing of the yacht.

[0030] Step four: define the second flow threshold, that is, the second flow threshold = 4 L / min x 90% = 3.6 L / min; When the real-time flow is 3.4 L / min after a certain time, that is, the second flow threshold 3.6 L / min is greater than the real-time flow 3.4 L / min, the control unit 5 confirms that the yacht enters the complete water state, and triggers the red constant light of the indicator light.

[0031] Step five: when the control unit 5 confirms that the yacht enters the complete water state, the control unit 5 sends an electrical signal to the speed limiting valve 41, adjusts the opening degree of the throttle port of the speed limiting valve 41 to the maximum, to improve the oil flow, and realizes the rapid separation of the fork arm 3 and the yacht.

[0032] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved. In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A control method for a forklift used for lowering a yacht, the forklift comprising a body, an actuator having a plurality of lifting cylinders, a fork arm, and an oil outlet passage; the actuator drives the fork arm up and down via the plurality of lifting cylinders; the lifting cylinders discharging oil into the oil outlet passage causes the fork arm to move downward; the method is characterized by: A speed limiting valve and an electromagnetic flow meter are provided at the connection ends of the plurality of lifting cylinders and the oil outlet channel; the electromagnetic flow meter monitors the flow of the speed limiting valve in real time; each of the speed limiting valves is arranged in parallel and is uniformly controlled by a control unit; The control method comprises the following steps: Step 1: Open the throttle of the speed limiting valve to the maximum and then lower the fork arm, collect the real-time flow of the speed limiting valve through the electromagnetic flowmeter, and transmit the real-time flow information to the control unit; Step 2: defining a first flow threshold; when the real-time flow rate is less than the first flow threshold, the control unit determines that the yacht has entered the initial water entry state; Step 3: When the control unit confirms that the yacht has entered the initial water entry state, the control unit sends an electrical signal to the speed limiting valve to adjust the throttle opening of the speed limiting valve to the minimum to limit the oil flow and achieve a cushioned landing of the yacht; Step 4: defining a second flow threshold; if the control unit detects that the real-time flow rate is less than the second flow threshold, the control unit determines that the yacht has entered a fully submerged state; Step 5: When the control unit confirms that the yacht has fully entered the water, the control unit sends an electrical signal to the speed limiting valve to adjust the throttle opening of the speed limiting valve to the maximum to increase the oil flow rate and achieve rapid separation of the fork arm from the yacht.

2. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The speed limiting valve is a stepless electromagnetic valve.

3. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The electromagnetic flowmeter is installed downstream of the speed limiting valve.

4. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The control unit is manually activated by the driver.

5. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The rated maximum oil output after the throttle opening of the speed limiting valve is maximized is defined as a first flow rate, and the definition range of the first flow rate threshold is 90% to 80% of the first flow rate.

6. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The rated maximum oil output after the throttle opening of the speed limiting valve is minimized is defined as a second flow rate, and the setting range of the second flow rate threshold is 90% to 80% of the second flow rate.

7. The control method for a forklift used for lowering a yacht according to claim 1, characterized in that: The control unit records the flow rate data of the electromagnetic flowmeter at a frequency of 50 Hz to 100 Hz to form sampling points, and takes the average value of the latest 10 to 15 sampling points as the real-time flow rate.

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