A vehicle and its control method

Abstract

This invention discloses a vehicle and its control method. The vehicle control method includes: determining a first target speed of the oil pump motor and a first target opening of the first proportional valve based on the first stroke of the lifting control lever; determining a second target speed of the oil pump motor when the actual height of the forks reaches the first buffer range of the current stage mast; determining a second target opening of the first proportional valve based on the actual height of the forks when the actual height of the forks reaches the first buffer range of the current stage mast; determining a third target speed of the oil pump motor based on the first target speed, the second target speed, and the actual height of the forks; determining a final target speed of the oil pump motor based on the first target speed and the third target speed; and controlling the operation of the oil pump motor based on the final target speed; determining a first final target opening of the first proportional valve based on the first target opening and the second target opening; and controlling the opening of the first proportional valve based on the first final target opening.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and more particularly to a vehicle and its control method. Background Technology

[0002] With the rapid development of vehicle technology, electric forklifts are becoming increasingly widely used. To enable the loading and unloading of goods at different heights, electric forklifts can be equipped with multi-stage masts, such as primary, secondary, and tertiary masts. The primary mast is mounted on the forklift, the secondary mast is slidably connected to the inside of the primary mast, and the tertiary mast is slidably connected to the inside of the secondary mast. The forks are mounted on the tertiary mast. When a lower height is required, the primary, secondary, and tertiary masts are stacked. When a higher height is required, the system can switch to the secondary mast; the hydraulic pump motor drives the secondary mast to lift, and the secondary mast then drives the tertiary mast and forks to lift. For even higher heights, the system can switch to the tertiary mast; in addition to the secondary mast's lifting capability, the hydraulic pump motor further lifts the tertiary mast, allowing the forks to reach a greater height.

[0003] However, due to the different dimensions of the masts of different grades, the working cross-sectional area of ​​the hydraulic cylinders corresponding to the masts of different grades is different. This causes the hydraulic pump motor to experience sudden load changes and sudden speed changes when switching masts, resulting in severe mast vibration. Summary of the Invention

[0004] This invention provides a vehicle and its control method to solve the problem of severe mast vibration during mast switching.

[0005] According to one aspect of the present invention, a vehicle control method is provided. The vehicle includes an n-stage mast, forks, a lifting lever, a controller, and an oil pump motor. The forks are located on the n-stage mast, and the (m+1)-th stage mast is slidably connected to the m-th stage mast. The oil pump motor is used to drive the mast and the forks to move. A first proportional valve is provided on a first oil circuit of the oil pump motor. The controller is connected to the oil pump motor, the lifting lever, and the first proportional valve. The vehicle control method is executed by the controller. Wherein, n is an integer greater than or equal to 2, and m is a positive integer.

[0006] The vehicle control method includes:

[0007] When the lifting control lever is activated, the first target speed of the oil pump motor and the first target opening of the first proportional valve are determined based on the first stroke of the lifting control lever.

[0008] When the actual height of the forks reaches the first buffer range of the current mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current and the full-load torque current corresponding to the next mast; wherein, the current mast is the mast with the smallest number of stages among the masts with the highest height among the masts that have been raised;

[0009] When the actual height of the forks reaches the first buffer range of the current mast, the second target opening degree of the first proportional valve is determined based on the actual height of the forks;

[0010] The third target speed of the oil pump motor is determined based on the first target speed, the second target speed, and the actual height of the forks. The final target speed of the oil pump motor is determined based on the first target speed and the third target speed. The operation of the oil pump motor is controlled based on the final target speed.

[0011] The first final target opening degree of the first proportional valve is determined based on the first target opening degree and the second target opening degree, and the opening degree of the first proportional valve is controlled based on the first final target opening degree.

[0012] Optionally, the vehicle further includes a lowering control lever, a second proportional valve is provided on the second oil line of the oil pump motor, and the controller is connected to the lowering control lever and the second proportional valve respectively;

[0013] The vehicle control method also includes:

[0014] When the lowering lever is activated, the third target opening degree of the second proportional valve is determined based on the second stroke of the lowering lever;

[0015] When the actual height of the forks reaches the second buffer range of the current mast, the fourth target opening of the second proportional valve is determined based on the actual height of the forks;

[0016] The second final target opening of the second proportional valve is determined based on the third target opening and the fourth target opening, and the opening of the second proportional valve is controlled based on the second final target opening.

[0017] Optionally, determining the second target opening degree of the first proportional valve based on the actual height of the forks includes:

[0018] The second target opening of the first proportional valve is determined based on the actual height of the forks, the first preset opening, the second preset opening, the first starting height of the first buffer range, and the first ending height; wherein, the first ending height is the height of the forks at the switching point where the current mast switches to the next mast, and the first starting height is less than the first ending height.

[0019] Optionally, determining the first final target opening of the first proportional valve based on the first target opening and the second target opening includes:

[0020] The minimum value between the first target opening and the second target opening is taken as the first final target opening.

[0021] Optionally, when the lifting control lever is activated, the vehicle control method further includes:

[0022] When the actual height of the forks is less than the first starting height of the first buffer range of the current mast, the opening of the first proportional valve is controlled according to the first target opening, and the operation of the oil pump motor is controlled according to the first target rotational speed.

[0023] When the actual height of the fork is greater than the first end height of the first buffer range of the current mast and less than the first start height of the first buffer range corresponding to the next mast, the opening of the first proportional valve is controlled according to the minimum value between the second preset opening and the first target opening, and the operation of the oil pump motor is controlled according to the minimum value between the first target speed and the second target speed.

[0024] Optionally, determining the third target speed of the oil pump motor based on the first target speed, the second target speed, and the actual height of the forks, and determining the final target speed of the oil pump motor based on the first target speed and the third target speed, includes:

[0025] Determine the difference between the actual height of the forks and the first starting height of the first buffer range of the current mast, and the first ratio of the difference between the first ending height and the first starting height of the first buffer range of the current mast;

[0026] Determine the first product of the difference between the second target speed and the first target speed and the first ratio;

[0027] The sum of the first target speed and the first product is taken as the third target speed, and the minimum value between the first target speed and the third target speed is taken as the final target speed.

[0028] Optionally, determining the second target speed of the oil pump motor based on the actual torque current of the oil pump motor corresponding to the current-level gantry, the no-load torque current, and the full-load torque current corresponding to the next-level gantry includes:

[0029] Determine a second ratio between the difference between the actual torque current and the full-load torque current and the difference between the no-load torque current and the full-load torque current;

[0030] Determine the second product of the difference between the second preset speed and the first preset speed and the second ratio;

[0031] The sum of the product of the first preset speed and the second speed is taken as the second target speed.

[0032] Optionally, determining the fourth target opening of the second proportional valve based on the actual height of the forks includes:

[0033] Determine the difference between the second starting height of the second buffer range of the current level mast and the actual height of the forks, and a third ratio to the difference between the second starting height and the second ending height of the second buffer range of the current level mast; wherein, the second starting height is the height of the switching point from the next level mast to the current level mast, and the second ending height is less than the second starting height;

[0034] Determine the third product of the difference between the fourth preset opening and the third preset opening and the third ratio;

[0035] The sum of the third preset opening and the third product is taken as the fourth target opening;

[0036] Determining the second final target opening of the second proportional valve based on the third target opening and the fourth target opening includes:

[0037] The minimum value between the third target opening and the fourth target opening is taken as the second final target opening.

[0038] Optionally, when the lowering lever is activated, the vehicle control method further includes:

[0039] When the actual height of the forks is greater than the second starting height of the second buffer range of the current mast, the opening of the second proportional valve is controlled according to the third target opening.

[0040] When the actual height of the forks is less than the second end height of the second buffer range of the current mast, the opening of the second proportional valve is controlled according to the minimum value of the fourth preset opening degree and the third target opening degree; wherein, the fourth preset opening degree is the target opening degree of the second proportional valve corresponding to the second end height of the second buffer range of the current mast.

[0041] Optionally, the forks are equipped with encoders, the encoders include two output channels, the output channels are connected to the controller, and the mast is equipped with proximity switches;

[0042] The vehicle control method also includes:

[0043] When the fork is determined to be in a lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is accumulated, and a period is determined at each height. The actual height of the fork is determined based on the accumulated number of pulses and a first preset correspondence. The first preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in a lifting state.

[0044] When the proximity switch is closed, the actual height of the forks is updated according to the height of the proximity switch, and the number of pulses output by the encoder is re-accumulated from zero.

[0045] The actual height of the fork is determined based on the accumulated pulse count and a second preset correspondence; wherein, the second preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in the lifting state.

[0046] When the fork is determined to be in a descending state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is cumulatively reduced, and a period is determined at each height. The actual height of the fork is determined based on the cumulative number of pulses and a third preset correspondence. The third preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in a descending state.

[0047] When the proximity switch is closed, the actual height of the forks is updated according to the height of the proximity switch, and the number of pulses output by the encoder is decremented from zero again.

[0048] The actual height of the fork is determined based on the cumulative pulse count and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in a descending state.

[0049] Optionally, the vehicle control method further includes:

[0050] If the encoder outputs a pulse signal when the vehicle's lifting or lowering lever is activated, then the encoder is determined to be faulty.

[0051] And / or, if the encoder has no output when the lifting operating lever is activated, the oil pump motor speed is not zero, and the oil pump motor current is less than the preset current, then the encoder is determined to be faulty.

[0052] Optionally, when determining that the fork is in a lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before accumulating the number of pulses output by the encoder before the proximity switch closes, the method further includes:

[0053] Control the lifting of the forks, determine the phase relationship between the two pulse signals output by the two output channels of the encoder when the forks are lifted, and accumulate the number of pulses output by the encoder to determine the first preset correspondence;

[0054] When the proximity switch is closed, the number of pulses output by the encoder is cleared to zero, and the number of pulses output by the encoder continues to accumulate until the torque current of the oil pump motor reaches the preset current, so as to determine the second preset correspondence.

[0055] When determining that the fork is in a lowered state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed and before the number of pulses output by the encoder is cumulatively reduced, the following steps are also included:

[0056] Controlling the fork descent, determining the phase relationship between the two pulse signals output by the two output channels of the encoder when the fork descent occurs, and cumulatively subtracting the number of pulses output by the encoder to determine the third preset correspondence;

[0057] When the proximity switch is closed, the number of pulses output by the encoder is cleared to zero, and the number of pulses output by the encoder continues to be decremented to determine the fourth preset correspondence.

[0058] According to another aspect of the present invention, a vehicle is provided, the vehicle comprising: an n-stage mast, forks, a lifting control lever, a controller, and an oil pump motor;

[0059] The forks are located on the nth mast, and the (m+1)th mast is slidably connected to the mth mast. The oil pump motor is used to drive the mast and the forks to move. A first proportional valve is provided on the first oil line of the oil pump motor. The controller is connected to the oil pump motor, the lifting operating lever and the first proportional valve respectively. The controller is used to execute the vehicle control method described in any embodiment of the present invention; where n is an integer greater than or equal to 2 and m is a positive integer.

[0060] The technical solution of this invention, when the lifting control lever is activated, determines the first target speed of the oil pump motor and the first target opening of the first proportional valve based on the first stroke of the lifting control lever. When the actual height of the forks reaches the first buffer range of the current stage mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current stage mast, the no-load torque current and the full-load torque current corresponding to the next stage mast. The third target speed of the oil pump motor is determined based on the first target speed, the second target speed, and the actual height of the forks. The final target speed of the oil pump motor is determined based on the first target speed and the third target speed, and the operation of the oil pump motor is controlled according to the final target speed, so that the actual height of the forks corresponds one-to-one with the third target speed, that is, the third target speed changes linearly with the actual height of the forks. When the third target speed is used as the final target speed of the oil pump motor, the speed of the oil pump motor can change linearly, allowing the speed of the oil pump motor to change gradually, avoiding sudden changes in the speed of the oil pump motor, thereby achieving a buffering effect and preventing severe shaking of the mast caused by sudden changes in the speed of the oil pump motor, which is beneficial to improving the stability of the vehicle. When the actual height of the forks reaches the first buffer range of the current stage mast, the second target opening of the first proportional valve is determined based on the actual height of the forks. The first final target opening of the first proportional valve is then determined based on the first and second target openings. The opening of the first proportional valve is controlled based on the first final target opening. When the actual height of the forks reaches the first buffer range of the current stage mast, the actual height of the forks corresponds one-to-one with the second target opening of the first proportional valve; that is, the second target opening of the first proportional valve changes linearly with the actual height of the forks. Therefore, the second target opening of the first proportional valve can be determined based on the actual height of the forks. Using the second target opening as the first final target opening allows the opening of the first proportional valve to gradually change with the actual height of the forks when the actual height of the forks reaches the first buffer range corresponding to the current stage mast. This causes the flow rate of the first oil circuit to gradually change, allowing the piston lifting speed and the oil pump motor speed to gradually change. This avoids sudden changes in the piston lifting speed and the oil pump motor speed, thus achieving a buffering effect and preventing severe mast vibration caused by sudden changes in the oil pump motor speed and piston lifting speed, which is beneficial for improving vehicle stability.

[0061] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a flowchart of a vehicle control method provided in an embodiment of the present invention;

[0064] Figure 2 This is a flowchart of another vehicle control method provided in an embodiment of the present invention;

[0065] Figure 3 This is a flowchart of another vehicle control method provided in an embodiment of the present invention;

[0066] Figure 4 This is a flowchart of another vehicle control method provided in an embodiment of the present invention;

[0067] Figure 5 This is a structural schematic diagram of a vehicle provided in an embodiment of the present invention. Detailed Implementation

[0068] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0069] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0070] This invention provides a vehicle control method. The vehicle includes an n-stage mast, forks, a lifting lever, a controller, and an oil pump motor. The forks are located on the n-stage mast, and the (m+1)-th stage mast is slidably connected to the m-th stage mast. The oil pump motor is used to drive the mast and forks to move. A first proportional valve is provided on the first oil line of the oil pump motor. The controller is connected to the oil pump motor, the lifting lever, and the first proportional valve. The vehicle control method is executed by the controller. Here, n is an integer greater than or equal to 2, and m is a positive integer.

[0071] The vehicle comprises n masts, i.e., n masts in total. The forks are fixed to the nth mast. An oil pump motor drives the mast to move, and the mast drives the forks to move. The (m+1)th mast is slidably connected to the mth mast, achieving a step-by-step connection. For example, if n is 3, the first mast is mounted on the electric forklift, the second mast is slidably connected to the inside of the first mast, the third mast is slidably connected to the inside of the second mast, and the forks are mounted on the third mast. The pipe diameter of the (m+1)th mast is smaller than that of the mth mast, resulting in a smaller working cross-sectional area of ​​the cylinder in the (m+1)th mast compared to the cylinder in the mth mast. A controller connected to the oil pump motor controls its speed. For example, the first oil circuit is the lifting circuit, which supplies oil to the oil pump motor when the forks are lifted. The controller can control whether the first proportional valve is open and control the opening degree of the first proportional valve, thereby controlling the flow rate of the first oil circuit, so that the flow rate of the first oil circuit is matched with the speed of the oil pump motor, that is, different speeds correspond to different flow rates. The lifting operating lever is the operating lever that controls the lifting of the forks. After the lifting operating lever is activated, the lifting operating lever moves, and the stroke of the lifting operating lever corresponds to the height of the forks.

[0072] Figure 1 This is a flowchart of a vehicle control method provided in an embodiment of the present invention, see reference. Figure 1 The vehicle control methods include:

[0073] S101. When the lifting operating lever is started, the first target speed of the oil pump motor and the first target opening degree of the first proportional valve are determined according to the first stroke of the lifting operating lever.

[0074] Specifically, the first stroke of the hoisting lever corresponds to the first target speed of the oil pump motor. When the controller determines that the hoisting lever should be started, it can obtain the first stroke of the hoisting lever. Based on the correspondence between the first stroke and the first target speed, and the first stroke itself, the first target speed of the oil pump motor can be determined. For example, if the range of the first stroke is 0%-100%, when the first stroke is 0%, the corresponding first target speed of the oil pump motor is 0. When the first stroke is 100%, the corresponding first target speed of the oil pump motor is the highest speed of the oil pump motor corresponding to the current gantry. Thus, a linear relationship between the first stroke and the first target speed can be determined. Substituting the determined first stroke of the hoisting lever into the linear relationship between the first stroke and the first target speed, the first target speed of the oil pump motor can be determined.

[0075] Different masts have different dimensions, and the maximum speed of the motors corresponding to different masts also differs. For example, the maximum speed of the oil pump motor corresponding to the first-level mast is the maximum speed specified at the factory. The maximum speed of the oil pump motor corresponding to the (m+1)th level mast is lower than the maximum speed of the oil pump motor corresponding to the m-th level mast. The current level mast is the mast with the smallest number of levels among the highest masts that have been raised. For example, n is 3. When all masts are stacked together, i.e., in their initial state, i.e., not yet raised, i.e., at the same height, the current mast is the first-level mast. When switching to the second-level mast, i.e., after the hydraulic pump motor drives the second-level mast to rise, the second-level mast drives the third-level mast and forks to rise. The second-level and third-level masts are at the same height. Among the raised masts, the highest mast is the second-level and third-level mast. Among the highest masts, the mast with the fewest levels is the second-level mast, i.e., the current mast is the second-level mast. In some embodiments, the mast height refers to the height of the bottom of the mast or the height of the top of the mast, and this is not limited here.

[0076] Specifically, since the first stroke of the lifting control lever corresponds to the first target opening of the first proportional valve, the first stroke can be substituted into the preset correspondence between the first stroke and the first target opening, thereby determining the first target opening of the first proportional valve based on the first stroke.

[0077] S102. When the actual height of the forks reaches the first buffer range of the current mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current and the full-load torque current corresponding to the next mast; wherein, the current mast is the mast with the smallest number of stages among the masts with the highest height that have been raised.

[0078] Each mast corresponds to a first buffer range, which extends from a first starting height to a first ending height. The first ending height is the height of the forks at the switching point, which is the point where the current mast switches to the next mast; that is, at the switching point, the next mast completes its lifting. The first starting height is less than the first ending height; for example, the first starting height is 70%, 80%, or 90% of the first ending height. This embodiment does not impose any limitations on this.

[0079] The level of the next-level gantry is the level of the current-level gantry plus one. For example, if the current-level gantry is level m, then the next-level gantry is level m+1. The maximum height that the next-level gantry can reach is greater than the maximum height that the current-level gantry can reach.

[0080] Specifically, the torque current of the hydraulic pump motor corresponds to its speed. Because the pipe diameters differ on different masts, the flow rates in those pipes also differ, resulting in different hydraulic pump motor speeds and torque currents on different masts. When switching to the current mast level, the hydraulic pump motor operates based on the actual torque current. When switching to the next mast level, the hydraulic pump motor operates based on the torque current corresponding to that next mast level. The torque current corresponding to the next mast level is greater than or equal to the full-load torque current of that next mast level, and less than or equal to the no-load torque current of that next mast level. The no-load torque current of the next mast level is the torque current of the hydraulic pump motor corresponding to the next mast level when the forks are lifted without load. The full-load torque current of the next mast level is the torque current of the hydraulic pump motor corresponding to the next mast level when the forks are lifted with full load. Full load for the forks means the fork load reaches the rated load indicated at the factory. The full-load and no-load torque currents for each mast level can be preset.

[0081] Specifically, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current, and the full-load torque current corresponding to the next mast. This second target speed is related to the actual torque current of the current mast, the no-load torque current of the next mast, and the full-load torque current of the next mast. The actual torque current of the oil pump motor corresponding to the current mast is related to the load of the forks. Therefore, the second target speed can be determined based on the load of the forks. The second target speed can be determined in conjunction with load changes, thereby adjusting the speed of the oil pump motor under different load conditions to reduce mast vibration. Even under different load conditions, mast vibration can be reduced, resulting in better vehicle control.

[0082] S103. When the actual height of the forks reaches the first buffer range of the current mast, determine the second target opening degree of the first proportional valve based on the actual height of the forks.

[0083] Specifically, a cable encoder is installed on the fork. The actual height of the fork can be determined based on the pulse signal output by the cable encoder. When the actual height of the fork reaches the first buffer range of the current mast stage, the actual height of the fork corresponds one-to-one with the second target opening of the first proportional valve. That is, when the actual height of the fork reaches the first buffer range of the current mast stage, the second target opening of the first proportional valve changes linearly with the actual height of the fork. Therefore, the second target opening of the first proportional valve can be determined based on the actual height of the fork. Thus, when the actual height of the fork reaches the first buffer range corresponding to the current mast stage, the opening of the first proportional valve can gradually change with the actual height of the fork, thereby gradually changing the flow rate of the first oil circuit. This allows for a gradual change in the piston's lifting speed, avoiding sudden changes in the piston's lifting speed, thus achieving a buffering effect and preventing severe mast vibration caused by sudden changes in piston lifting speed, which is beneficial to improving vehicle stability. Furthermore, it allows the flow rate of the first oil circuit to correspond to the speed of the oil pump motor.

[0084] S104. Determine the third target speed of the oil pump motor based on the first target speed, the second target speed and the actual height of the forks. Determine the final target speed of the oil pump motor based on the first target speed and the third target speed. Control the operation of the oil pump motor based on the final target speed.

[0085] Specifically, the third target speed of the oil pump motor is determined based on the first target speed, the second target speed, and the actual height of the fork, so that the third target speed is a value between the first target speed and the second target speed, and the third target speed is related to the actual height of the fork. By controlling the operation of the oil pump motor according to the third target speed, the speed of the oil pump motor can be gradually changed to the second target speed.

[0086] When the actual height of the forks reaches the first buffer range of the current stage mast, the actual height of the forks corresponds one-to-one with the third target speed, meaning the third target speed changes linearly with the actual height of the forks. Using the third target speed as the final target speed of the hydraulic pump motor allows for a linear change in the motor's speed, enabling gradual changes and avoiding sudden speed changes. This achieves a buffering effect, preventing severe mast vibration caused by sudden speed changes in the hydraulic pump motor, and improving vehicle stability.

[0087] The final target speed of the oil pump motor is determined based on the first target speed and the third target speed. For example, the minimum value between the first target speed and the third target speed can be used as the final target speed. This will result in a smaller final target speed for the oil pump motor, which is closer to the target speed of the oil pump motor corresponding to the next level mast. This ensures that the oil pump motor speed will not change abruptly when the fork height reaches the switching point, thus avoiding severe mast vibration caused by sudden changes in oil pump motor speed and improving vehicle stability.

[0088] S105. Determine the first final target opening degree of the first proportional valve based on the first target opening degree and the second target opening degree, and control the opening degree of the first proportional valve based on the first final target opening degree.

[0089] If the diameter of the oil circuit corresponding to the next level gantry is smaller than the diameter of the oil circuit corresponding to the current level gantry, then the opening degree of the first proportional valve corresponding to the next level gantry is smaller than the opening degree of the oil circuit corresponding to the current level gantry.

[0090] Specifically, the first final target opening of the first proportional valve is determined based on the first target opening and the second target opening. For example, the minimum of the first and second target openings can be used as the first final target opening. This results in a smaller first final target opening of the hydraulic pump motor, which is closer to the opening of the first proportional valve corresponding to the next stage mast. The opening of the first proportional valve is related to the speed of the hydraulic pump motor, thereby further ensuring that the hydraulic pump motor speed and piston lifting speed do not change abruptly when the fork height reaches the switching point. This further avoids severe mast vibration caused by sudden changes in the hydraulic pump motor speed and piston lifting speed, thus improving vehicle stability. In this way, mast vibration problems can be effectively avoided during fork lifting and mast switching.

[0091] In this embodiment, when the lifting control lever is activated, a first target speed of the hydraulic pump motor and a first target opening of the first proportional valve are determined based on the first stroke of the lifting control lever. When the actual height of the forks reaches the first buffer range of the current stage mast, a second target speed of the hydraulic pump motor is determined based on the actual torque current of the hydraulic pump motor corresponding to the current stage mast, the no-load torque current, and the full-load torque current corresponding to the next stage mast. A third target speed of the hydraulic pump motor is determined based on the first target speed, the second target speed, and the actual height of the forks. Finally, the final target speed of the hydraulic pump motor is determined based on the first and third target speeds, and the operation of the hydraulic pump motor is controlled according to the final target speed, so that the actual height of the forks corresponds one-to-one with the third target speed, that is, the third target speed changes linearly with the actual height of the forks. By using the third target speed as the final target speed of the hydraulic pump motor, the speed of the hydraulic pump motor can change linearly, allowing the speed of the hydraulic pump motor to change gradually, avoiding sudden changes in the speed of the hydraulic pump motor, thereby achieving a buffering effect and preventing severe shaking of the mast caused by sudden changes in the speed of the hydraulic pump motor, which is beneficial to improving the stability of the vehicle. When the actual height of the forks reaches the first buffer range of the current stage mast, the second target opening of the first proportional valve is determined based on the actual height of the forks. The first final target opening of the first proportional valve is then determined based on the first and second target openings. The opening of the first proportional valve is controlled based on the first final target opening. When the actual height of the forks reaches the first buffer range of the current stage mast, the actual height of the forks corresponds one-to-one with the second target opening of the first proportional valve; that is, the second target opening of the first proportional valve changes linearly with the actual height of the forks. Therefore, the second target opening of the first proportional valve can be determined based on the actual height of the forks. Using the second target opening as the first final target opening allows the opening of the first proportional valve to gradually change with the actual height of the forks when the actual height of the forks reaches the first buffer range corresponding to the current stage mast. This causes the flow rate of the first oil circuit to gradually change, allowing the piston lifting speed and the oil pump motor speed to gradually change. This avoids sudden changes in the piston lifting speed and the oil pump motor speed, thus achieving a buffering effect and preventing severe mast vibration caused by sudden changes in the oil pump motor speed and piston lifting speed, which is beneficial for improving vehicle stability.

[0092] Based on the above technical solution, optionally, the vehicle also includes a lowering control lever. A second proportional valve is installed on the second oil circuit of the oil pump motor. The controller is connected to both the lowering control lever and the second proportional valve. The lowering control lever controls the lowering of the forks. After the lowering control lever is activated, it moves, and the stroke of the lowering control lever corresponds to the height of the forks. For example, the second oil circuit is the lowering oil circuit, which is the pipeline for oil return during fork lowering. The controller can control whether the second proportional valve is open and control the opening degree of the second proportional valve, thereby controlling the flow rate of the second oil circuit, and thus controlling the lowering speed of the piston rod and the lowering speed of the forks.

[0093] Figure 2 This is a flowchart of another vehicle control method provided in an embodiment of the present invention. Optionally, refer to... Figure 2 The vehicle control methods include:

[0094] S201. When the lifting operating lever is started, the first target speed of the oil pump motor and the first target opening degree of the first proportional valve are determined according to the first stroke of the lifting operating lever.

[0095] S202. When the actual height of the forks reaches the first buffer range of the current mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current and the full-load torque current corresponding to the next mast; wherein, the current mast is the mast with the smallest number of stages among the masts with the highest height that have been raised.

[0096] S203. When the actual height of the forks reaches the first buffer range of the current mast, determine the second target opening degree of the first proportional valve based on the actual height of the forks.

[0097] S204. Determine the third target speed of the oil pump motor based on the first target speed, the second target speed and the actual height of the forks. Determine the final target speed of the oil pump motor based on the first target speed and the third target speed. Control the operation of the oil pump motor based on the final target speed.

[0098] S205. Determine the first final target opening degree of the first proportional valve based on the first target opening degree and the second target opening degree, and control the opening degree of the first proportional valve based on the first final target opening degree.

[0099] S206. When the lowering lever is activated, the third target opening degree of the second proportional valve is determined based on the second stroke of the lowering lever.

[0100] Specifically, since the second stroke of the lowering control lever corresponds to the third target opening of the second proportional valve, the second stroke can be substituted into the preset correspondence between the second stroke and the third target opening to determine the third target opening of the second proportional valve based on the second stroke.

[0101] S207. When the actual height of the forks reaches the second buffer range of the current mast, determine the fourth target opening of the second proportional valve based on the actual height of the forks.

[0102] Each mast corresponds to a second buffer range, which extends from the second starting height to the second ending height. The second starting height is the height of the forks at the switching point, which is the point where the next-level mast switches to the current-level mast; that is, at the switching point, the next-level mast completes its descent. For example, if the current-level mast is the m-th level mast, then the next-level mast is the (m+1)-th level mast. The second ending height is less than the second starting height.

[0103] Specifically, when the actual height of the forks reaches the second buffer range of the current mast, the actual height of the forks corresponds one-to-one with the fourth target opening of the second proportional valve. That is, when the actual height of the forks reaches the second buffer range of the current mast, the fourth target opening of the second proportional valve changes linearly with the actual height of the forks. Therefore, the fourth target opening of the second proportional valve can be determined based on the actual height of the forks. Thus, when the actual height of the forks reaches the second buffer range corresponding to the current mast, the opening of the second proportional valve can gradually change with the actual height of the forks. For example, as the height decreases, the opening of the second proportional valve gradually increases. This causes the flow rate of the second hydraulic circuit to change gradually, allowing the fork descent speed to change gradually, avoiding sudden changes in the fork descent speed, thereby achieving a buffering effect, preventing severe mast vibration, and improving vehicle stability.

[0104] This ensures that when the next level mast switches to the current level mast (when the (m+1)th level mast switches to the mth level mast), the opening of the second proportional valve will not increase instantaneously, thus preventing the fork descent speed from increasing instantaneously and avoiding severe mast vibration during fork descent, which helps improve vehicle stability.

[0105] It should be noted that during the fork descent, the descent is based on gravity, and the oil pump motor speed is no longer controlled by the torque current provided by the controller. Therefore, by controlling the opening of the second proportional valve, the flow rate of the second oil circuit can be controlled, thereby controlling the piston's movement speed and thus the descent speed of the forks.

[0106] S208. Determine the second final target opening of the second proportional valve based on the third target opening and the fourth target opening, and control the opening of the second proportional valve based on the second final target opening.

[0107] Specifically, when the actual height of the forks reaches the second buffer range of the current stage mast, the second final target opening of the second proportional valve is determined based on the third and fourth target openings. For example, the minimum of the third and fourth target openings can be used as the second final target opening, which makes the second final target opening of the second proportional valve smaller and closer to the opening of the second proportional valve corresponding to the next stage mast. This further ensures that the fork speed does not change abruptly when the fork height reaches the switching point. In this way, mast vibration can be effectively avoided when the forks descend and the mast switches.

[0108] Based on the above technical solutions, optionally, the second target opening degree of the first proportional valve is determined according to the actual height of the forks, including:

[0109] The second target opening of the first proportional valve is determined based on the actual height of the forks, the first preset opening, the second preset opening, the first starting height of the first buffer range, and the first ending height; wherein, the first ending height is the height of the forks at the switching point from the current mast to the next mast, and the first starting height is less than the first ending height.

[0110] Wherein, the second preset opening is the preset target opening of the first proportional valve corresponding to the first end height of the current gantry, and the first preset opening is the preset target opening of the first proportional valve corresponding to the first start height of the current gantry.

[0111] For example, the actual height of the forks is The second preset opening is The first preset opening is The first starting height is The first ending height is Then the second target opening for In this way, the second target opening of the first proportional valve changes linearly with the actual height of the forks. Thus, when the actual height of the forks reaches the first buffer range corresponding to the current stage mast, the opening of the first proportional valve can gradually change with the actual height of the forks. This causes the flow rate of the first oil circuit to gradually change, allowing the piston's lifting speed to gradually change, avoiding sudden changes in piston lifting speed. This achieves a buffering effect, preventing severe mast vibration caused by sudden changes in piston lifting speed, and improving vehicle stability.

[0112] Based on the above technical solutions, optionally, determining the first final target opening of the first proportional valve according to the first target opening and the second target opening includes:

[0113] The minimum value between the first target opening and the second target opening is taken as the first final target opening.

[0114] Specifically, the controller can periodically determine the actual height of the forks, thereby periodically determining the second target opening. After each determination of the second target opening, the first target opening is compared with the second target opening. If the first target opening is greater than the second target opening, the second target opening is used as the first final target opening. If the first target opening is less than the second target opening, the first target opening is used as the first final target opening. If the first target opening is equal to the second target opening, either the first or second target opening can be used as the first final target opening. This ensures that the first final target opening of the hydraulic pump motor is smaller, closer to the opening of the first proportional valve corresponding to the next stage mast, further guaranteeing that the hydraulic pump motor speed and piston lifting speed do not change abruptly when the fork height reaches the switching point. This further avoids severe mast vibration caused by sudden changes in hydraulic pump motor speed and piston lifting speed, thus improving vehicle stability. In this way, mast vibration problems can be effectively avoided during fork lifting and mast switching.

[0115] Based on the above technical solutions, Figure 3 This is a flowchart of another vehicle control method provided in an embodiment of the present invention. Optionally, refer to... Figure 3 The vehicle control methods include:

[0116] S301. When the lifting operating lever is started, the first target speed of the oil pump motor and the first target opening degree of the first proportional valve are determined according to the first stroke of the lifting operating lever.

[0117] S302. Determine whether the actual height of the forks is less than the first starting height of the first buffer range of the current mast. If yes, proceed to step S303; otherwise, proceed to step S304.

[0118] S303. Control the opening degree of the first proportional valve according to the first target opening degree, and control the operation of the oil pump motor according to the first target speed.

[0119] Specifically, when the actual height of the forks is greater than the first end height of the first buffer range of the previous mast and less than the first starting height of the first buffer range of the current mast, the opening of the first proportional valve is controlled according to the first target opening degree, and the operation of the oil pump motor is controlled according to the first target speed. This allows the oil pump motor to operate at a higher speed when the actual height of the forks is less than the first starting height of the first buffer range of the current mast, thus satisfying the first target speed and first target opening degree corresponding to the lifting operating lever and preventing the forks from rising too slowly.

[0120] S304. Determine whether the actual height of the forks is greater than the first end height of the first buffer range of the current mast. If not, proceed to step S305; if yes, proceed to step S309.

[0121] S305. Determine the second target speed of the oil pump motor based on the actual torque current of the oil pump motor corresponding to the current stage gantry, the no-load torque current and the full-load torque current corresponding to the next stage gantry; wherein, the current stage gantry is the gantry with the smallest number of stages among the highest gantry among the raised gantry.

[0122] S306. When the actual height of the forks reaches the first buffer range of the current mast, determine the second target opening degree of the first proportional valve based on the actual height of the forks.

[0123] S307. Determine the third target speed of the oil pump motor based on the first target speed, the second target speed and the actual height of the forks, determine the final target speed of the oil pump motor based on the first target speed and the third target speed, and control the operation of the oil pump motor based on the final target speed.

[0124] S308. Determine the first final target opening degree of the first proportional valve based on the first target opening degree and the second target opening degree, and control the opening degree of the first proportional valve based on the first final target opening degree.

[0125] S309. When the actual height of the forks is greater than the first end height of the first buffer range of the current mast and less than the first start height of the first buffer range of the next mast, the opening of the first proportional valve is controlled according to the minimum value between the second preset opening and the first target opening, and the oil pump motor is controlled to run according to the minimum value between the first target speed and the second target speed.

[0126] Specifically, the diameter of the hydraulic circuit in the next-level mast is smaller than the diameter of the hydraulic circuit in the current-level mast. The second preset opening is the target opening of the first proportional valve corresponding to the first end height of the current-level mast. When the actual height of the forks is greater than the first end height of the first buffer range of the current-level mast, but less than the first starting height of the first buffer range of the next-level mast, the opening of the first proportional valve is controlled according to the minimum value between the second preset opening and the first target opening, so that the opening of the first proportional valve is smaller after switching to the next-level mast, which conforms to the smaller diameter hydraulic circuit. Furthermore, the operation of the oil pump motor is controlled according to the minimum value between the first target speed and the second target speed, so that the speed of the oil pump motor is matched with the opening of the first proportional valve, that is, the speed of the oil pump motor is matched with the flow rate of the hydraulic circuit.

[0127] Based on the above technical solutions, optionally, a third target speed of the oil pump motor is determined according to the first target speed, the second target speed, and the actual height of the forks; and the final target speed of the oil pump motor is determined according to the first target speed and the third target speed, including:

[0128] Step a1: Determine the difference between the actual height of the forks and the first starting height of the first buffer range of the current mast, and the first ratio of the difference between the first ending height and the first starting height of the first buffer range of the current mast.

[0129] For example, the actual height of the forks is The first starting height of the first buffer range of the current stage gantry is The first end height of the first buffer range of the current stage gantry is The difference between the actual height of the forks and the first starting height of the first buffer range of the current mast is . The difference between the first end height and the first start height of the first buffer range of the current stage gantry is Then the first ratio is .

[0130] Step a2: Determine the first product of the difference between the second target speed and the first target speed and the first ratio.

[0131] For example, the first target rotational speed is The second target rotational speed is The difference between the second target rotational speed and the first target rotational speed is Then the first product is .

[0132] Step a3: Take the sum of the first target speed and the first product as the third target speed, and take the minimum value between the first target speed and the third target speed as the final target speed.

[0133] For example, the third target rotational speed for This design ensures that within the first buffer range corresponding to the current mast level, the third target speed changes linearly with the actual fork height. Using this third target speed as the final target speed for the hydraulic pump motor allows for a linear change in its speed, enabling gradual adjustments and preventing sudden speed changes, thus achieving a buffering effect. Using the minimum of the first and third target speeds as the final target speed results in a smaller final target speed for the hydraulic pump motor, closer to the target speed of the hydraulic pump motor corresponding to the next mast level. This further ensures that the hydraulic pump motor speed does not change abruptly when the fork height reaches the switching point, further preventing severe mast vibration caused by sudden speed changes and improving vehicle stability.

[0134] Based on the above technical solutions, optionally, the second target speed of the oil pump motor is determined according to the actual torque current of the oil pump motor corresponding to the current stage gantry, the no-load torque current and the full-load torque current corresponding to the next stage gantry, including:

[0135] Step b1: Determine the second ratio of the difference between the actual torque current and the full-load torque current to the difference between the no-load torque current and the full-load torque current.

[0136] Specifically, the actual torque current of the oil pump motor corresponding to the current gantry is the same as the actual torque current of the oil pump motor before switching. The difference between the actual torque current and the full-load torque current is the actual torque current of the oil pump motor corresponding to the current gantry minus the torque current of the oil pump motor corresponding to the next gantry when the oil pump motor is fully loaded. The difference between the no-load torque current and the full-load torque current is the torque current of the oil pump motor corresponding to the next gantry when the oil pump motor is no-load, minus the torque current of the oil pump motor corresponding to the next gantry when the oil pump motor is fully loaded.

[0137] For example, the actual torque current of the oil pump motor corresponding to the current stage gantry is... The full-load torque current of the oil pump motor corresponding to the next level gantry. The no-load torque current corresponding to the next stage gantry is Then the second ratio is .

[0138] The actual torque current of the oil pump motor corresponding to the current mast is related to the load of the forks. By determining the second ratio, the proportion of torque current corresponding to the load of the forks can be determined.

[0139] Step b2: Determine the second product of the difference between the second preset speed and the first preset speed and the second ratio.

[0140] Specifically, the second preset speed is the preset target speed of the hydraulic pump motor corresponding to the next level mast when the forks are lifted under no-load. The first preset speed is the preset target speed of the hydraulic pump motor corresponding to the next level mast when the forks are lifted under full load.

[0141] For example, the first preset rotation speed is The second preset speed is The difference between the second preset speed and the first preset speed is Then the second product is .

[0142] Step b3: The sum of the first preset speed and the second product is taken as the second target speed.

[0143] For example, the second target rotational speed is ,but In this way, the second target speed can be determined based on the load on the forks, and the second target speed can be determined in combination with load changes. Thus, the speed of the oil pump motor can be adjusted to reduce mast vibration under different load conditions, thereby reducing mast vibration under different load conditions and enabling better vehicle control.

[0144] Based on the above technical solutions, optionally, the fourth target opening degree of the second proportional valve is determined according to the actual height of the forks, including:

[0145] Step c1: Determine the difference between the second starting height of the second buffer range of the current mast and the actual height of the forks, and the third ratio between the difference between the second starting height and the second ending height of the second buffer range of the current mast; wherein, the second starting height is the height of the switching point from the next mast to the current mast, and the second ending height is less than the second starting height.

[0146] When the forks descend, the mast switches from the next level mast to the current level mast. For example, if the current level mast is the m-th level mast, then the next level mast is the (m+1)-th level mast.

[0147] For example, the actual height of the forks is The second starting height of the second buffer range of the current stage gantry is The second end height of the second buffer range of the current stage gantry is The difference between the second starting height of the second buffer range of the current mast and the actual height of the forks is... The difference between the second starting height and the second ending height of the second buffer range of the current stage gantry is Then the second ratio is .

[0148] Step c2: Determine the difference between the fourth preset opening and the third preset opening, and the third product of the third ratio.

[0149] The third preset opening is the preset target opening of the second proportional valve corresponding to the second starting height of the second buffer range of the current gantry, and the fourth preset opening is the preset target opening of the second proportional valve corresponding to the second ending height of the second buffer range of the current gantry.

[0150] For example, the third preset opening is The fourth preset opening degree is Then the third product is .

[0151] Step c3: The sum of the third preset opening and the third product is taken as the fourth target opening.

[0152] For example, the fourth objective opening is ,but In this way, when the actual height of the forks reaches the second buffer range of the current mast, the fourth target opening of the second proportional valve changes linearly with the actual height of the forks, thereby causing the flow rate of the second oil circuit to change gradually, and the speed of the oil pump motor to change gradually, avoiding sudden changes in the speed of the oil pump motor, thus achieving a buffering effect.

[0153] Optionally, determining the second final target opening of the second proportional valve based on the third target opening and the fourth target opening includes:

[0154] The minimum value between the third target opening and the fourth target opening is taken as the second final target opening.

[0155] Specifically, the controller can periodically determine the actual height of the forks, thereby periodically determining the fourth target opening. After each determination of the fourth target opening, the minimum value between the third and fourth target openings is taken as the second final target opening. This makes the second final target opening of the oil pump motor smaller and closer to the opening of the second proportional valve corresponding to the next mast, thereby further ensuring that the oil pump motor speed does not change abruptly when the fork height reaches the switching point.

[0156] Based on the above technical solutions, Figure 4 This is a flowchart of another vehicle control method provided in an embodiment of the present invention. Optionally, refer to... Figure 4 The vehicle control methods include:

[0157] S401. When the lifting operating lever is started, the first target speed of the oil pump motor and the first target opening degree of the first proportional valve are determined according to the first stroke of the lifting operating lever.

[0158] S402. When the actual height of the forks reaches the first buffer range of the current mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current and the full-load torque current corresponding to the next mast; wherein, the current mast is the mast with the smallest number of stages among the masts with the highest height that have been raised.

[0159] S403. When the actual height of the forks reaches the first buffer range of the current mast, determine the second target opening degree of the first proportional valve based on the actual height of the forks.

[0160] S404. Determine the third target speed of the oil pump motor based on the first target speed, the second target speed and the actual height of the forks, determine the final target speed of the oil pump motor based on the first target speed and the third target speed, and control the operation of the oil pump motor based on the final target speed.

[0161] S405. Determine the first final target opening degree of the first proportional valve based on the first target opening degree and the second target opening degree, and control the opening degree of the first proportional valve based on the first final target opening degree.

[0162] S406. When the lowering lever is activated, the third target opening degree of the second proportional valve is determined based on the second stroke of the lowering lever.

[0163] S407. Determine whether the actual height of the forks is greater than the second starting height of the second buffer range of the current mast. If yes, proceed to step S408; otherwise, proceed to step S409.

[0164] S408. Control the opening degree of the second proportional valve according to the third target opening degree.

[0165] Specifically, under the current mast level, when the forks have not descended to the second buffer range, the opening of the second proportional valve is controlled according to the third target opening corresponding to the stroke of the descent lever. This ensures that the descent speed of the forks matches the stroke of the descent lever; for example, the greater the stroke of the descent lever, the greater the opening of the second proportional valve, and the greater the descent speed of the forks. Thus, by controlling the opening of the second proportional valve according to the third target opening, the descent of the forks is not too slow.

[0166] S409. Determine whether the actual height of the forks is less than the second end height of the second buffer range of the current mast. If not, proceed to step S410; if yes, proceed to step S412.

[0167] S410. When the actual height of the forks reaches the second buffer range of the current mast, determine the fourth target opening of the second proportional valve based on the actual height of the forks.

[0168] S411. Determine the second final target opening of the second proportional valve based on the third target opening and the fourth target opening, and control the opening of the second proportional valve based on the second final target opening.

[0169] S412. When the actual height of the forks is less than the second end height of the second buffer range of the current mast, the opening of the second proportional valve is controlled according to the minimum value of the fourth preset opening degree and the third target opening degree; wherein, the fourth preset opening degree is the target opening degree of the second proportional valve corresponding to the second end height of the second buffer range of the current mast.

[0170] Specifically, when the actual height of the forks under the current mast is less than the second end height of the second buffer range of the current mast, it indicates that the mast switching has been completed. The opening of the second proportional valve is controlled according to the minimum value between the fourth preset opening and the third target opening, so that the opening of the second proportional valve is small, avoiding a large increase in the opening of the second proportional valve, thereby avoiding a large increase in the descent speed of the forks, and ensuring the stable descent of the forks.

[0171] Based on the above technical solutions, the method for determining the actual height of the forks will be explained below, but this is not intended to limit this application.

[0172] Optionally, an encoder is installed on the forks, the encoder having two output channels connected to the controller, and a proximity switch is installed on the mast. The encoder can be a wire encoder, and both output channels can output pulse signals to the controller. The proximity switch, whose height is known, closes when the forks reach it.

[0173] Alternatively, the vehicle control method may also include:

[0174] Step d1: When the fork is in the lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is accumulated, and a period is determined at each height. The actual height of the fork is determined based on the accumulated number of pulses and the first preset correspondence. The first preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in the lifting state.

[0175] In this embodiment, the phase relationship of the two pulse signals output by the two output channels of the encoder corresponds to the state of the fork. For example, the two output channels include a first output channel and a second output channel, and the two pulse signals include a first pulse signal and a second pulse signal. The first output channel outputs the first pulse signal, and the second output channel outputs the second pulse signal. For example, when the phase of the first pulse signal leads the phase of the second pulse signal, the fork is in a raised state; when the phase of the first pulse signal is delayed, the fork is in a lowered state. Alternatively, when the phase of the first pulse signal leads the phase of the second pulse signal, the fork is in a lowered state; when the phase of the first pulse signal is delayed, the fork is in a raised state. This embodiment does not impose any limitations on this.

[0176] The controller can periodically determine the actual height of the forks, that is, it determines the actual height of the forks once in each height determination cycle.

[0177] Specifically, when the forks are determined to be in the lifting state, before the proximity switch is closed (i.e., when the fork height is less than the proximity switch height), the number of pulses output by the encoder is accumulated from zero. That is, for each valid level (high or low), the pulse count is incremented by one. This accumulation can be performed on the pulse count from either the first or second output channel; no limitation is made here. In each height determination cycle, the actual height of the forks is determined based on the accumulated pulse count and a first preset correspondence. This allows for determining the actual height when the fork height is less than the proximity switch height, facilitating the determination of the third target speed of the oil pump motor, the second target opening degree of the first proportional valve, and the fourth target opening degree of the second proportional valve based on the actual fork height.

[0178] Step d2: When the proximity switch is closed, update the actual height of the forks according to the height of the proximity switch, and re-accumulate the number of pulses output by the encoder from zero.

[0179] Specifically, when the proximity switch is closed, it indicates that the actual height of the forks has reached the height of the proximity switch. The actual height of the forks is then updated based on the height of the proximity switch, making the determined actual height more accurate. This achieves calibration of the actual height of the forks and avoids error accumulation caused by the accumulation of pulse counts.

[0180] The number of pulses output by the encoder is re-accumulated from zero, which avoids the error in the actual height of the forks from increasing continuously due to the continuous accumulation of pulses.

[0181] Step d3: Determine the actual height of the fork based on the accumulated pulse count and the second preset correspondence; wherein, the second preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in the lifting state.

[0182] Specifically, after the forks continue to rise from the proximity switch, and the pulse count restarts, the actual height of the forks can be determined at each height period based on the accumulated pulse count and the second preset correspondence.

[0183] Step d4: When the fork is in a descending state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is accumulated and subtracted, and a period is determined at each height. The actual height of the fork is determined based on the accumulated number of pulses and the third preset correspondence. The third preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in a descending state.

[0184] Specifically, when the forks are determined to be in a lowered state, before the proximity switch closes (i.e., when the fork height is higher than the proximity switch height), the number of pulses output by the encoder is subtracted from the number of pulses after the last accumulation. That is, for each valid level detected, the pulse count is decremented by one. This subtraction can be performed on the pulse count from either the first or second output channel; no limitation is made here. In each height determination cycle, the actual height at which the fork height is higher than the proximity switch height is determined based on the subtracted pulse count and a third preset correspondence.

[0185] Step d5: When the proximity switch is closed, update the actual height of the forks according to the height of the proximity switch, and start the encoder output pulse count from zero again.

[0186] Specifically, when the proximity switch is closed, it indicates that the actual height of the forks has reached the height of the proximity switch. The actual height of the forks is then updated based on the height of the proximity switch, making the determined actual height more accurate. This achieves calibration of the actual height of the forks and avoids error accumulation caused by the cumulative decrease of pulse count.

[0187] Step d6: Determine the actual height of the fork based on the cumulative pulse count and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in a descending state.

[0188] Specifically, starting from the height of the proximity switch, the number of pulses is decremented from zero. A period is determined at each height, and the actual height of the forks can be determined based on the correspondence between the decremented number of pulses and the fourth preset value.

[0189] Based on the above technical solutions, in order to accurately determine the actual height of the forks, it is necessary to perform fault detection on the encoder. The fault detection method is described below, but it is not intended to limit this application.

[0190] Alternatively, the vehicle control method may also include:

[0191] If the encoder outputs a pulse signal when the vehicle's lifting or lowering lever is activated, an encoder malfunction is confirmed.

[0192] And / or, if the encoder has no output when the lifting control lever is activated, the oil pump motor speed is not zero, and the oil pump motor current is less than the preset current, then the encoder is determined to be faulty.

[0193] Specifically, when the vehicle's lifting or lowering lever is activated, if the encoder outputs a pulse signal, it indicates that the channel where the encoder is not outputting a pulse signal is faulty, that is, the channel where the pulse signal is not outputting is disconnected, which indicates an encoder fault. The first warning message can be issued to facilitate timely repair.

[0194] The preset current is the torque current of the hydraulic pump motor when the forks reach their maximum height. The forks reach their maximum height when all masts have completed lifting. When the forks reach their maximum height, the hydraulic pump motor is unloaded, causing the torque current of the hydraulic pump motor to continuously accumulate and increase, reaching a relatively large preset current.

[0195] When the lifting control lever is activated, and the oil pump motor speed is not zero, and the oil pump motor current is less than the preset current, that is, when the forks are lifting but have not reached the maximum height, if the encoder has no output, that is, neither of the two output channels of the encoder outputs a pulse signal, it is determined that both channels of the encoder have broken wires, indicating an encoder fault. A second prompt message can be issued to facilitate timely repair.

[0196] Based on the above technical solutions, the determination methods of the first, second, third, and fourth preset correspondences are explained below, but this is not intended to limit this application.

[0197] Optionally, when determining that the forks are in a lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before accumulating the number of pulses output by the encoder before the proximity switch closes, the method further includes:

[0198] Step e1: Control the fork lifting, determine the phase relationship of the two pulse signals output by the two output channels of the encoder when the fork is lifted, and accumulate the number of pulses output by the encoder to determine the first preset correspondence.

[0199] Specifically, when the vehicle is not in use, the controller controls the forks to rise unloaded from the initial position (lowest position), meaning all masts begin to rise from the first-level mast. During the lifting process, two pulse signals output from the two output channels of the encoder are acquired and their phase relationship is stored, thus storing the phase relationship of the two pulse signals corresponding to the fork lifting. Furthermore, the number of pulses output by the encoder is accumulated from zero. Based on the accumulated pulse count and the measured fork height, the correspondence between the pulse count and the actual fork height is determined, which is the first preset correspondence.

[0200] Step e2: When the proximity switch is closed, clear the number of pulses output by the encoder and continue to accumulate the number of pulses output by the encoder until the torque current of the oil pump motor reaches the preset current, so as to determine the second preset correspondence.

[0201] Specifically, when the proximity switch is closed, that is, when the actual height of the fork rises to the height of the proximity switch, the number of pulses output by the encoder is cleared, and the number of pulses output by the encoder continues to accumulate. Based on the accumulated number of pulses and the measured height of the fork, the correspondence between the number of pulses and the actual height of the fork is determined, which is the second preset correspondence.

[0202] Optionally, when determining that the fork is in a lowered state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed and before the number of pulses output by the encoder is cumulatively reduced, the method further includes:

[0203] Step f1: Control the forks to descend, determine the phase change relationship of the encoder pulse count corresponding to the forks descending, and cumulatively subtract the encoder output pulse count to determine the third preset correspondence.

[0204] Specifically, when the vehicle is not in use, the controller controls the forks to descend from their highest position, meaning all masts begin descending from the nth mast. During this descent, two pulse signals from the encoder's two output channels are acquired and their phase relationship is stored. This stores the phase relationship between the two pulse signals corresponding to the fork descent. Furthermore, the number of pulses output by the encoder is incremented from the last accumulated value. Based on the incremented pulse count and the measured fork height, a third preset correspondence is determined between the pulse count and the actual fork height.

[0205] Step f2: When the proximity switch is closed, clear the number of pulses output by the encoder and continue to decrement the number of pulses output by the encoder to determine the fourth preset correspondence.

[0206] Specifically, when the proximity switch is closed, that is, when the actual height of the fork rises to the height of the proximity switch, the number of pulses output by the encoder is cleared and the number of pulses output by the encoder continues to be reduced. Based on the reduced number of pulses and the measured height of the fork, the correspondence between the number of pulses and the actual height of the fork is determined, which is the fourth preset correspondence.

[0207] This invention also provides a vehicle. Figure 5 This is a structural schematic diagram of a vehicle provided in an embodiment of the present invention, for reference. Figure 5 The vehicle includes: n-level mast 501, forks 502, lifting control lever 503, controller 504, and oil pump motor 505;

[0208] The forks 502 are located on the nth mast 501, and the (m+1)th mast is slidably connected to the mth mast. The oil pump motor 505 is used to drive the mast 501 and the forks 502 to move. A first proportional valve 506 is provided on the first oil line of the oil pump motor 505. The controller 504 is connected to the oil pump motor 505, the lifting operating lever 503 and the first proportional valve 506 respectively. The controller 504 is used to execute the vehicle control method provided in any embodiment of the present invention; where n is an integer greater than or equal to 2 and m is a positive integer.

[0209] like Figure 5 As shown, for example, when n is 3, the first-level gantry 501 (1) can be connected to the front of the vehicle, the second-level gantry 501 (2) is slidably connected to the inside of the first-level gantry 501 (1), and the third-level gantry 501 (3) is slidably connected to the inside of the second-level gantry 501 (2).

[0210] The controller 504 is used to execute the vehicle control method provided in any embodiment of the present invention. Therefore, the controller in this embodiment has the same beneficial effects as the vehicle control method provided in any embodiment of the present invention, and will not be described again here.

[0211] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0212] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for controlling a vehicle, characterized in that, The vehicle includes an n-stage mast, forks, a lifting lever, a controller, and an oil pump motor. The forks are located on the n-stage mast, and the (m+1)-th stage mast is slidably connected to the m-th stage mast. The oil pump motor drives the mast and forks to move. A first proportional valve is installed on the first oil line of the oil pump motor. The controller is connected to the oil pump motor, the lifting lever, and the first proportional valve. The control method of the vehicle is executed by the controller. Wherein, n is an integer greater than or equal to 2, and m is a positive integer. The vehicle control method includes: When the lifting control lever is activated, the first target speed of the oil pump motor and the first target opening degree of the first proportional valve are determined based on the first stroke of the lifting control lever. When the actual height of the forks reaches the first buffer range of the current mast, the second target speed of the oil pump motor is determined based on the actual torque current of the oil pump motor corresponding to the current mast, the no-load torque current and the full-load torque current corresponding to the next mast; wherein, the current mast is the mast with the smallest number of stages among the masts with the highest height; each mast corresponds to a first buffer range, and the first buffer range is from the first starting height to the first ending height; When the actual height of the forks reaches the first buffer range of the current mast, the second target opening degree of the first proportional valve is determined based on the actual height of the forks; The third target speed of the oil pump motor is determined based on the first target speed, the second target speed, and the actual height of the forks. The final target speed of the oil pump motor is determined based on the first target speed and the third target speed. The operation of the oil pump motor is controlled based on the final target speed. The first final target opening degree of the first proportional valve is determined based on the first target opening degree and the second target opening degree, and the opening degree of the first proportional valve is controlled based on the first final target opening degree.

2. The method according to claim 1, characterized in that, The vehicle also includes a descent control lever, and a second proportional valve is provided on the second oil line of the oil pump motor. The controller is connected to the descent control lever and the second proportional valve respectively. The vehicle control method also includes: When the lowering lever is activated, the third target opening degree of the second proportional valve is determined based on the second stroke of the lowering lever; When the actual height of the forks reaches the second buffer range of the current mast, the fourth target opening of the second proportional valve is determined based on the actual height of the forks; The second final target opening of the second proportional valve is determined based on the third target opening and the fourth target opening, and the opening of the second proportional valve is controlled based on the second final target opening.

3. The method according to claim 1, characterized in that, Determining the second target opening of the first proportional valve based on the actual height of the forks includes: The second target opening of the first proportional valve is determined based on the actual height of the forks, the first preset opening, the second preset opening, the first starting height of the first buffer range, and the first ending height; wherein, the first ending height is the height of the forks at the switching point where the current mast switches to the next mast, the first starting height is less than the first ending height, the second preset opening is the preset target opening of the first proportional valve corresponding to the first ending height of the current mast, and the first preset opening is the preset target opening of the first proportional valve corresponding to the first starting height of the current mast.

4. The method according to any one of claims 1-3, characterized in that, Determining the first final target opening of the first proportional valve based on the first target opening and the second target opening includes: The minimum value between the first target opening and the second target opening is taken as the first final target opening.

5. The method according to claim 3, characterized in that, When the lifting control lever is activated, the vehicle control method further includes: When the actual height of the forks is less than the first starting height of the first buffer range of the current mast, the opening of the first proportional valve is controlled according to the first target opening, and the operation of the oil pump motor is controlled according to the first target rotational speed. When the actual height of the fork is greater than the first end height of the first buffer range of the current mast and less than the first start height of the first buffer range corresponding to the next mast, the opening of the first proportional valve is controlled according to the minimum value between the second preset opening and the first target opening, and the operation of the oil pump motor is controlled according to the minimum value between the first target speed and the second target speed.

6. The method according to any one of claims 1-3, characterized in that, The step of determining the third target speed of the oil pump motor based on the first target speed, the second target speed, and the actual height of the forks, and determining the final target speed of the oil pump motor based on the first target speed and the third target speed, includes: Determine the difference between the actual height of the forks and the first starting height of the first buffer range of the current mast, and the first ratio of the difference between the first ending height and the first starting height of the first buffer range of the current mast; Determine the first product of the difference between the second target speed and the first target speed and the first ratio; The sum of the first target speed and the first product is taken as the third target speed, and the minimum value between the first target speed and the third target speed is taken as the final target speed.

7. The method according to any one of claims 1-3, characterized in that, The step of determining the second target speed of the oil pump motor based on the actual torque current of the oil pump motor corresponding to the current stage gantry, the no-load torque current and the full-load torque current corresponding to the next stage gantry includes: Determine a second ratio between the difference between the actual torque current and the full-load torque current and the difference between the no-load torque current and the full-load torque current; Determine the second product of the difference between the second preset speed and the first preset speed and the second ratio; wherein, the second preset speed is the preset target speed of the oil pump motor corresponding to the next level mast when the forks are lifted without load, and the first preset speed is the preset target speed of the oil pump motor corresponding to the next level mast when the forks are lifted with full load. The sum of the product of the first preset speed and the second speed is taken as the second target speed.

8. The method according to claim 2, characterized in that, Determining the fourth target opening of the second proportional valve based on the actual height of the forks includes: Determine the difference between the second starting height of the second buffer range of the current level mast and the actual height of the forks, and a third ratio to the difference between the second starting height and the second ending height of the second buffer range of the current level mast; wherein, the second starting height is the height of the switching point from the next level mast to the current level mast, and the second ending height is less than the second starting height; Determine the difference between the fourth preset opening and the third preset opening, and the third product of the third ratio; wherein the third preset opening is the preset target opening of the second proportional valve corresponding to the second starting height of the second buffer range corresponding to the current gantry, and the fourth preset opening is the preset target opening of the second proportional valve corresponding to the second ending height of the second buffer range corresponding to the current gantry. The sum of the third preset opening and the third product is taken as the fourth target opening; Determining the second final target opening of the second proportional valve based on the third target opening and the fourth target opening includes: The minimum value between the third target opening and the fourth target opening is taken as the second final target opening.

9. The method according to claim 2, characterized in that, When the lowering lever is activated, the vehicle control method further includes: When the actual height of the forks is greater than the second starting height of the second buffer range of the current mast, the opening of the second proportional valve is controlled according to the third target opening. When the actual height of the forks is less than the second end height of the second buffer range of the current mast, the opening of the second proportional valve is controlled according to the minimum value of the fourth preset opening degree and the third target opening degree; wherein, the fourth preset opening degree is the target opening degree of the second proportional valve corresponding to the second end height of the second buffer range of the current mast.

10. The method according to any one of claims 1-3, characterized in that, The forks are equipped with encoders, which include two output channels connected to the controller. The mast is equipped with proximity switches. The vehicle control method also includes: When the fork is determined to be in a lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is accumulated, and a period is determined at each height. The actual height of the fork is determined based on the accumulated number of pulses and a first preset correspondence. The first preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in a lifting state. When the proximity switch is closed, the actual height of the forks is updated according to the height of the proximity switch, and the number of pulses output by the encoder is re-accumulated from zero. The actual height of the fork is determined based on the accumulated pulse count and a second preset correspondence; wherein, the second preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in the lifting state. When the fork is determined to be in a descending state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed, the number of pulses output by the encoder is cumulatively reduced, and a period is determined at each height. The actual height of the fork is determined based on the cumulative number of pulses and a third preset correspondence. The third preset correspondence is the correspondence between the number of pulses and the actual height when the height of the fork is greater than the height of the proximity switch and the fork is in a descending state. When the proximity switch is closed, the actual height of the forks is updated according to the height of the proximity switch, and the number of pulses output by the encoder is decremented from zero again. The actual height of the fork is determined based on the cumulative pulse count and the fourth preset correspondence; wherein, the fourth preset correspondence is the correspondence between the pulse count and the actual height when the height of the fork is less than the height of the proximity switch and the fork is in a descending state.

11. The method according to claim 10, characterized in that, The vehicle control method also includes: If the encoder outputs a pulse signal when the vehicle's lifting or lowering lever is activated, then the encoder is determined to be faulty. And / or, if the encoder has no output when the lifting operating lever is activated, the oil pump motor speed is not zero, and the oil pump motor current is less than the preset current, then the encoder is determined to be faulty.

12. The method according to claim 10, characterized in that, When determining that the fork is in a lifting state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed and before accumulating the number of pulses output by the encoder, the process further includes: Control the lifting of the forks, determine the phase relationship between the two pulse signals output by the two output channels of the encoder when the forks are lifted, and accumulate the number of pulses output by the encoder to determine the first preset correspondence; When the proximity switch is closed, the number of pulses output by the encoder is cleared to zero, and the number of pulses output by the encoder continues to accumulate until the torque current of the oil pump motor reaches the preset current, so as to determine the second preset correspondence. When determining that the fork is in a lowered state based on the phase relationship of the two pulse signals output by the two output channels of the encoder, before the proximity switch is closed and before the number of pulses output by the encoder is cumulatively reduced, the following steps are also included: Controlling the fork descent, determining the phase relationship between the two pulse signals output by the two output channels of the encoder when the fork descent occurs, and cumulatively subtracting the number of pulses output by the encoder to determine the third preset correspondence; When the proximity switch is closed, the number of pulses output by the encoder is cleared to zero, and the number of pulses output by the encoder continues to be decremented to determine the fourth preset correspondence.

13. A vehicle, characterized in that, include: n-level mast, forks, lifting levers, controllers, and hydraulic pump motors; The forks are located on the nth mast, and the (m+1)th mast is slidably connected to the mth mast. The oil pump motor is used to drive the mast and the forks to move. A first proportional valve is provided on the first oil line of the oil pump motor. The controller is connected to the oil pump motor, the lifting operating lever and the first proportional valve respectively. The controller is used to execute the vehicle control method according to any one of claims 1-12; where n is an integer greater than or equal to 2 and m is a positive integer.

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