Telescopic boom forklift truck control system and method

Abstract

The telescopic boom forklift truck control system comprises a steering gear assembly communicated with a hydraulic oil tank through a working pump, a front axle steering oil cylinder and a rear axle steering oil cylinder, the front axle steering oil cylinder and the rear axle steering oil cylinder are communicated with the steering gear assembly through a reversing valve assembly, and the reversing valve assembly comprises a front axle steering valve and a rear axle steering valve; the front axle steering valve is provided with a first electromagnet and a first locking electromagnet which are used for controlling the valve element to act. The rear axle steering valve is provided with a second electromagnet, a third electromagnet and a second locking electromagnet which are used for controlling the valve element to act. An L port of the steering gear assembly is communicated with a P port of the rear axle steering valve, an R port of the steering gear assembly is communicated with a T port of the front axle steering valve, and the T port of the rear axle steering valve is communicated with a P port of the front axle steering valve. The front axle steering valve and the rear axle steering valve are arranged, and front axle steering, rear axle steering, crab steering and all-wheel steering and multiple steering modes are achieved through valve element position switching and combined use of the two valves.

Description

Technical Field

[0001] The present invention relates to a steering control system and method for a telescopic boom forklift truck, belonging to the technical field of construction machinery. Background Art

[0002] Telescopic boom forklift trucks are widely used in construction projects, warehousing and logistics, agriculture and animal husbandry, etc., and are commonly used in high-rise building material handling (such as steel, precast slabs, scaffolding), high-altitude installation work, narrow-space material transfer, bale stacking, feed handling, high-altitude picking in orchards, livestock shed cleaning, etc., which require transporting materials to high places.

[0003] In order to adapt to different working requirements, existing telescopic boom forklift trucks have designed and implemented various steering methods, including conventional front-wheel steering and all-wheel steering and crab steering applicable to special working conditions. However, during the working process of telescopic boom forklift trucks, especially during the handling and transportation of materials, it is necessary to maintain the stability of the fork-mounted materials. However, existing telescopic boom forklift trucks do not have an independent rear-wheel steering function. Therefore, a more comprehensive steering system is needed to meet the working conditions of telescopic boom forklift trucks and improve the stability during the steering of the whole machine. Summary of the Invention

[0004] Object of the Invention: Aiming at the deficiencies in the prior art, the present invention adds a rear-wheel steering switch on the basis of the existing steering mode. This steering mode is applicable to adjusting the direction during the walking process of the whole machine when transporting materials. Its main purpose is to ensure that the sway of the chassis of the whole machine is reduced as much as possible when the rear axle adjusts the direction, so that the fork-mounted materials will not fall off. This steering mode enriches the working conditions of the whole machine and improves the steering stability.

[0005] Technical Solution: A control system for a telescopic boom forklift truck includes a steering gear assembly communicated with a hydraulic oil tank through a working pump and a front axle steering cylinder and a rear axle steering cylinder communicated with the steering gear assembly through a reversing valve assembly. The reversing valve assembly includes a front axle steering valve communicated with the front axle steering cylinder and a rear axle steering valve communicated with the rear axle steering cylinder; The front axle steering valve is a two-position four-way solenoid valve, and is provided with a first electromagnet for controlling the movement of the valve core and a first locking electromagnet for locking the position of the valve core; The rear axle steering valve is a three-position four-way solenoid valve, and is provided with a second electromagnet, a third electromagnet for controlling the movement of the valve core and a second locking electromagnet for locking the position of the valve core; The L port of the steering gear assembly is communicated with the P port of the rear axle steering valve, the R port is communicated with the T port of the front axle steering valve, and the T port of the rear axle steering valve is communicated with the P port of the front axle steering valve.

[0006] In the present invention, by providing a front axle steering valve and a rear axle steering valve, through the switching of the spool positions of the two valves and their combined use, front axle steering, rear axle steering, crab steering, and all-wheel steering are achieved. With multiple steering modes, during actual application, the corresponding suitable steering mode can be selected according to the working conditions. Especially in the case where a telescopic forklift lacks rear-wheel steering, during the material handling process, rear-wheel steering can be adopted for steering, effectively improving the stability of material handling, making the vehicle functions more abundant, having a wider application range, and higher working efficiency.

[0007] The steering gear assembly includes a reversing valve that controls the movement of the spool through the vehicle steering wheel, and a check valve provided on the make-up oil pipeline between the main oil inlet pipeline between the reversing valve and the steering valve assembly and the hydraulic oil tank. An overflow valve parallel to the check valve is provided between the main oil inlet pipeline and the make-up oil pipeline.

[0008] The function of the check valve is that when the steering speed of the steering wheel is too fast, a vacuum phenomenon may occur in the oil inlet pipeline, or the instantaneous pressure may be too low. By providing the check valve, hydraulic oil can be supplemented when the oil pressure in the main oil inlet pipeline is low, keeping the oil pressure in a normal state. The setting of the overflow valve is to protect the safety of the oil circuit.

[0009] Angle sensors are provided at the hinge joints of the front vehicle axle with the left and right front wheels and at the hinge joints of the rear vehicle axle with the left and right rear wheels. The angle sensors are signal-connected to the whole machine controller for monitoring the wheel rotation angle.

[0010] Setting the angle sensors can monitor the wheel rotation angle in real time. In a vehicle with multiple steering modes, if the wheel angle is not reset within a predetermined range, switching to other steering modes may cause deviation in the wheel steering angle, seriously dragging the wheel movement, causing tire wear, and affecting driving safety at the same time. The stability of material transportation cannot be guaranteed either.

[0011] A control method for a telescopic forklift control system includes a front-wheel steering mode, a crab steering mode, an all-wheel steering mode, and a rear-wheel steering mode; During the working process, when the front-wheel steering angle X≥1° or the rear-wheel steering angle Y≥1°, a correction mode is triggered; In the correction mode state, there are two switching logics, namely an allowable switching logic and a prohibited switching logic. Among them, the allowable switching logic is specifically as follows: Switching from the crab steering mode to the front-wheel steering mode or the rear-wheel steering mode; Switching from the all-wheel steering mode to the front-wheel steering mode or the rear-wheel steering mode; Switching from the front-wheel steering mode to the rear-wheel steering mode; Switching from the rear-wheel steering mode to the front-wheel steering mode; The prohibited switching logic is specifically as follows: When the driver operates the control panel to switch from the crab steering mode to the all-wheel steering mode, or from the all-wheel steering mode to the crab steering mode, or from the front-wheel steering mode to the crab steering mode, or from the front-wheel steering mode to the all-wheel steering mode, or from the rear-wheel steering mode to the crab steering mode, or from the rear-wheel steering mode to the all-wheel steering mode, an alarm is issued, the display screen prompts for prior correction, and it is reset to the steering mode of the vehicle before switching.

[0012] The specific front-wheel steering mode is as follows: When the whole machine is switched to the front-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly to the steering system, and the first electromagnet, the second electromagnet, the third electromagnet, the first locking electromagnet, and the second locking electromagnet of the front axle steering valve and the rear axle steering valve are all de-energized; When the steering wheel is operated for right steering, the hydraulic oil is output from the oil port R of the steering gear assembly, transported through the pipeline to the oil port T of the front axle steering valve, output from the oil port B of the front axle steering valve after passing through the front axle steering valve, transported through the pipeline to the oil port V1 of the front axle steering cylinder, and the front axle steering cylinder acts; The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder to the oil port A of the front axle steering valve through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve to the oil port T of the rear axle steering valve through the pipeline. The oil port P and the oil port T of the rear axle steering valve are connected, and the hydraulic oil is connected from the oil port P of the rear axle steering valve to the oil port L of the steering gear assembly through the pipeline to complete the right steering; The oil flow direction of the left steering is opposite to that of the right steering.

[0013] The specific crab steering mode is as follows: When the whole machine is switched to the crab steering mode, the hydraulic oil is distributed through the steering gear assembly to the steering system, the first electromagnet and the first locking electromagnet of the front axle steering valve and the second electromagnet of the rear axle steering valve are de-energized, and the third electromagnet and the second locking electromagnet of the rear axle steering valve are energized; When the steering wheel is operated for right steering, the hydraulic oil is output from the oil port R of the steering gear assembly, transported through the pipeline to the oil port T of the front axle steering valve, output from the oil port B of the front axle steering valve after passing through the front axle steering valve, transported through the pipeline to the oil port V1 of the front axle steering cylinder, and the front axle steering cylinder acts; The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder to the oil port A of the front axle steering valve through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve to the oil port T of the rear axle steering valve through the pipeline. The oil port T and the oil port B of the rear axle steering valve are connected, the oil port P and the oil port A are connected, and the hydraulic oil enters the oil port V2 of the rear axle steering cylinder through the pipeline connection, and the rear axle steering cylinder acts; The hydraulic oil is transported back from the oil port V1 of the rear axle steering cylinder to the oil port A of the rear axle steering valve through a pipeline. The oil ports P and A inside the rear axle steering valve are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve to the oil port L of the steering gear assembly through a pipeline to complete the right turn. The oil flow direction of the left turn is opposite to that of the right turn.

[0014] The full-wheel steering mode is specifically as follows: When the whole machine is switched to the full-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly to the steering system. The first electromagnet, the first locking electromagnet of the front axle steering valve, and the third electromagnet of the rear axle steering valve are de-energized, and the second electromagnet and the second locking electromagnet of the rear axle steering valve are energized. When operating the steering wheel for a right turn, the hydraulic oil is output from the oil port R of the steering gear assembly, transported through a pipeline to the oil port T of the front axle steering valve, output from the oil port B of the front axle steering valve after passing through the front axle steering valve, and transported through a pipeline to the oil port V1 of the front axle steering cylinder, and the front axle steering cylinder acts. The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder to the oil port A of the front axle steering valve through a pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve to the oil port T of the rear axle steering valve through a pipeline. The oil port T and the oil port A of the rear axle steering valve are connected, the oil port P and the oil port B are connected, and the hydraulic oil enters the oil port V1 of the rear axle steering cylinder through a pipeline connection, and the rear axle steering cylinder acts. The hydraulic oil is transported back from the oil port V2 of the rear axle steering cylinder to the oil port B of the rear axle steering valve through a pipeline. The oil ports P and B inside the rear axle steering valve are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve to the oil port L of the steering gear assembly through a pipeline to complete the right turn. The oil flow direction of the left turn is opposite to that of the right turn.

[0015] The rear-wheel steering mode is specifically as follows: When the whole machine is switched to the rear-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly to the steering system. The first electromagnet, the first locking electromagnet of the front axle steering valve, the second electromagnet of the rear axle steering valve, and the second locking solenoid valve are all energized, and the third electromagnet is de-energized. When operating the steering wheel for a right turn, it is transported through a pipeline to the oil port T of the front axle steering valve. The oil port T and the oil port P of the front axle steering valve are connected, and it is transported through a pipeline to the oil port T of the rear axle steering valve. At this time, the internal oil passage of the rear axle steering valve is that the oil port T and the oil port A are connected, and the oil port P and the oil port B are connected. The hydraulic oil enters the oil port V1 of the rear axle steering cylinder through a pipeline connection, and the rear axle steering cylinder acts. The hydraulic oil is transported back from the oil port V2 of the rear axle steering cylinder to the oil port B of the front axle steering valve through a pipeline. The internal oil ports P and B of the rear axle steering valve are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve to the oil port L of the steering gear assembly through a pipeline to complete the right turn. The left turn has an oil flow direction opposite to that of its right turn.

[0016] In the initial steering mode selection, when the front-wheel steering mode is selected, the first locking electromagnet and the second locking electromagnet are not energized; when the crab steering mode is selected, the second locking electromagnet is first energized, and the third electromagnet is energized t milliseconds after being energized; after T seconds, the second locking electromagnet is de-energized, and the third electromagnet is de-energized t milliseconds after being de-energized; when the all-wheel steering mode is selected, the second locking electromagnet is first energized, and the second electromagnet is energized t milliseconds after being energized; after T seconds, the second locking electromagnet is de-energized, and the second electromagnet is de-energized t milliseconds after being de-energized; when the rear-wheel steering mode is selected, the first locking electromagnet and the second locking electromagnet are first energized, and the first electromagnet and the second electromagnet are energized t milliseconds after being energized; after T seconds, the first locking electromagnet and the second locking electromagnet are de-energized, and the first electromagnet and the second electromagnet are de-energized t milliseconds after being de-energized; where t ranges from 100 to 500 and T ranges from 1 to 3.

[0017] During the switching process of the steering mode, the switching conditions need to be met, that is, X < 1° and Y < 1°.

[0018] Advantageous effects: By setting the front axle steering valve and the rear axle steering valve, and through the switching of the spool positions of the two valves, the present invention combines the use to achieve front axle steering, rear axle steering, crab steering and all-wheel steering, multiple steering modes. In the actual application process, the corresponding suitable steering mode can be selected according to the working conditions. Especially in the case where the telescopic forklift lacks rear-wheel steering, during the material handling process, the rear-wheel steering method can be adopted for steering, effectively improving the stability of material handling, the vehicle functions are more abundant, the application range is wider, and the working efficiency is higher.

[0019] When selecting the steering mode, the locking electromagnet is energized before the working electromagnet, which can ensure the smooth adjustment of the spool position and avoid the spool jamming affecting the switching of the steering mode. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0021] Figure 1 This is the hydraulic schematic diagram of the present invention.

[0022] Figure 2 This is the energizing sequence table of the electromagnet of the present invention, in which the representations of the first locking electromagnet and the second locking electromagnet are omitted. Specific embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0025] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is less than that of the second feature.

[0026] As Figure 1 and 2 shown, a telescopic boom forklift truck control system includes a steering gear assembly 3 communicated with a hydraulic oil tank 2 through a working pump 1, and a front axle steering cylinder 4 and a rear axle steering cylinder 5 communicated with the steering gear assembly 3 through a reversing valve 31 assembly. The steering valve assembly includes a front axle steering valve 6 communicated with the front axle steering cylinder 4 and a rear axle steering valve 7 communicated with the rear axle steering cylinder 5; The front axle steering valve 6 is a two-position four-way solenoid valve, and is provided with a first electromagnet 61 for controlling the movement of the valve core and a first locking electromagnet 62 for locking the position of the valve core; The rear axle steering valve 7 is a three-position four-way solenoid valve, and is provided with a second electromagnet 71, a third electromagnet 72 for controlling the movement of the valve core and a second locking electromagnet 73 for locking the position of the valve core; The L port of the steering gear assembly 3 is connected to the P port of the rear axle steering valve 7, the R port is connected to the T port of the front axle steering valve 6, and the T port of the rear axle steering valve 7 is connected to the P port of the front axle steering valve 6.

[0027] In the present invention, by providing the front axle steering valve 6 and the rear axle steering valve 7, through the switching of the spool positions of the two valves and combined use, front axle steering, rear axle steering, crab steering, and all-wheel steering, multiple steering modes are realized. During the actual application process, the corresponding suitable steering mode can be selected according to the working conditions. Especially in the case where the telescopic forklift lacks rear-wheel steering, during the material handling process, the rear-wheel steering method can be adopted for steering, effectively improving the stability of material handling, and the vehicle functions are also more abundant, the application range is wider, and the working efficiency is higher.

[0028] The steering gear assembly 3 includes a reversing valve 31 that controls the movement of the spool through the vehicle steering wheel, and a check valve 32 provided on the make-up oil pipeline between the main oil inlet pipeline between the reversing valve 31 and the steering valve assembly and the hydraulic oil tank 2. An overflow valve 33 is provided in parallel with the check valve 32 between the main oil inlet pipeline and the make-up oil pipeline.

[0029] The function of the check valve 32 is that when the steering speed of the steering wheel is too fast, a vacuum phenomenon may occur in the oil inlet pipeline, or the instantaneous pressure is too low. By providing the check valve 32, hydraulic oil can be supplemented when the oil pressure in the main oil inlet pipeline is low, keeping the pressure of the oil in a normal state. The setting of the overflow valve 33 is to protect the safety of the oil circuit.

[0030] Angle sensors are provided at the hinge joints of the front vehicle axle with the left and right front wheels and the hinge joints of the rear vehicle axle with the left and right rear wheels. The angle sensors are signal-connected to the whole machine controller for monitoring the wheel rotation angle.

[0031] Setting the angle sensors can monitor the wheel rotation angle in real time. In a vehicle with multiple steering modes, if the wheel angle is not reset within the predetermined range, switching to other steering modes will cause deviation in the wheel steering angle, seriously dragging the wheel movement, causing tire wear, and at the same time affecting driving safety, and the stability of material transportation cannot be guaranteed.

[0032] Including front-wheel steering mode, crab steering mode, all-wheel steering mode, and rear-wheel steering mode; During the working process, when the front-wheel steering angle X≥1° or the rear-wheel steering angle Y≥1°, the correction mode is triggered; In the correction mode state, there are two switching logics, namely the allowable switching logic and the prohibited switching logic. Among them, the allowable switching logic is specifically: Switch from the crab steering mode to the front-wheel steering mode or the rear-wheel steering mode; Switch from the all-wheel steering mode to the front-wheel steering mode or the rear-wheel steering mode; Switch from the front-wheel steering mode to the rear-wheel steering mode; Switch from the rear-wheel steering mode to the front-wheel steering mode; The prohibited switching logic is specifically as follows: When the driver operates the control panel to switch from the crab steering mode to the all-wheel steering mode, or from the all-wheel steering mode to the crab steering mode, or from the front-wheel steering mode to the crab steering mode, or from the front-wheel steering mode to the all-wheel steering mode, or from the rear-wheel steering mode to the crab steering mode, or from the rear-wheel steering mode to the all-wheel steering mode, an alarm is issued, the display screen prompts for prior correction, and it is reset to the steering mode in which the vehicle was before the switch.

[0033] The specific front-wheel steering mode is as follows: When the whole machine is switched to the front-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly 3 to the steering system, and the first electromagnet 61, the second electromagnet 71, the third electromagnet 72, the first locking electromagnet 62, and the second locking electromagnet 73 of the front axle steering valve 6 and the rear axle steering valve 7 are all de-energized; When the steering wheel is operated for a right turn, the hydraulic oil is output from the oil port R of the steering gear assembly 3, transported through the pipeline to the oil port T of the front axle steering valve 6, output from the oil port B of the front axle steering valve 6 after passing through the front axle steering valve 6, transported through the pipeline to the oil port V1 of the front axle steering cylinder 4, and the front axle steering cylinder 4 acts; The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder 4 to the oil port A of the front axle steering valve 6 through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve 6 to the oil port T of the rear axle steering valve 7 through the pipeline. The oil ports P and T of the rear axle steering valve 7 are connected, and the hydraulic oil is connected from the oil port P of the rear axle steering valve 7 to the oil port L of the steering gear assembly 3 through the pipeline to complete the right turn; The oil flow direction for a left turn is opposite to that for a right turn.

[0034] The specific crab steering mode is as follows: When the whole machine is switched to the crab steering mode, the hydraulic oil is distributed through the steering gear assembly 3 to the steering system, the first electromagnet 61 and the first locking electromagnet 62 of the front axle steering valve 6 and the second electromagnet 71 of the rear axle steering valve 7 are de-energized, and the third electromagnet 72 and the second locking electromagnet 73 of the rear axle steering valve 7 are energized; When the steering wheel is operated for a right turn, the hydraulic oil is output from the oil port R of the steering gear assembly 3, transported through the pipeline to the oil port T of the front axle steering valve 6, output from the oil port B of the front axle steering valve 6 after passing through the front axle steering valve 6, transported through the pipeline to the oil port V1 of the front axle steering cylinder 4, and the front axle steering cylinder 4 acts; The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder 4 to the oil port A of the front axle steering valve 6 through a pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve 6 to the oil port T of the rear axle steering valve 7 through a pipeline. The oil port T of the rear axle steering valve 7 is connected to the oil port B, and the oil port P is connected to the oil port A. The hydraulic oil enters the oil port V2 of the rear axle steering cylinder 5 through a pipeline connection, and the rear axle steering cylinder 5 acts; The hydraulic oil is transported back from the oil port V1 of the rear axle steering cylinder 5 to the oil port A of the rear axle steering valve 7 through a pipeline. The oil port P and the oil port A inside the rear axle steering valve 7 are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve 7 to the L oil port of the steering gear assembly 3 through a pipeline to complete a right turn; The left turn has the opposite oil flow direction to its right turn.

[0035] The specific all-wheel steering mode is as follows: When the whole machine is switched to the all-wheel steering mode, the hydraulic oil is distributed by the steering gear assembly 3 to the steering system. The first electromagnet 61, the first locking electromagnet 62 of the front axle steering valve 6 and the third electromagnet 72 of the rear axle steering valve 7 are de-energized, and the second electromagnet 71 and the second locking electromagnet 73 of the rear axle steering valve 7 are energized; When operating the steering wheel for a right turn, the hydraulic oil is output from the oil port R of the steering gear assembly 3, transported to the oil port T of the front axle steering valve 6 through a pipeline, output from the oil port B of the front axle steering valve 6 after passing through the front axle steering valve 6, and transported to the oil port V1 of the front axle steering cylinder 4 through a pipeline, and the front axle steering cylinder 4 acts; The hydraulic oil is transported back from the oil port V2 of the front axle steering cylinder 4 to the oil port A of the front axle steering valve 6 through a pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve 6 to the oil port T of the rear axle steering valve 7 through a pipeline. The oil port T of the rear axle steering valve 7 is connected to the oil port A, and the oil port P is connected to the oil port B. The hydraulic oil enters the oil port V1 of the rear axle steering cylinder 5 through a pipeline connection, and the rear axle steering cylinder 5 acts; The hydraulic oil is transported back from the oil port V2 of the rear axle steering cylinder 5 to the oil port B of the rear axle steering valve 7 through a pipeline. The oil port P and the oil port B inside the rear axle steering valve 7 are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve 7 to the oil port L of the steering gear assembly 3 through a pipeline to complete a right turn; The left turn has the opposite oil flow direction to its right turn.

[0036] The specific rear-wheel steering mode is as follows: When the whole machine is switched to the rear-wheel steering mode, the hydraulic oil is distributed by the steering gear assembly 3 to the steering system. The first electromagnet 61, the first locking electromagnet 62 of the front axle steering valve 6, the second electromagnet 71 of the rear axle steering valve 7 and the second locking solenoid valve are all energized, and the third electromagnet 72 is de-energized; When operating the steering wheel for a right turn, the oil is transported through a pipeline to the port T of the front axle steering valve 6. The port T and the port P of the front axle steering valve 6 are connected, and the oil is transported through a pipeline to the port T of the rear axle steering valve 7. At this time, the internal oil passage of the rear axle steering valve 7 is such that the port T is connected to the port A, and the port P is connected to the port B. The hydraulic oil enters the port V1 of the rear axle steering cylinder 5 through a pipeline connection, and the rear axle steering cylinder 5 operates; The hydraulic oil is transported back from the port V2 of the rear axle steering cylinder 5 to the port B of the front axle steering valve 6 through a pipeline. The port P and the port B inside the rear axle steering valve 7 are connected. The hydraulic oil is connected from the port P of the rear axle steering valve 7 to the port L of the steering gear assembly 3 through a pipeline to complete the right turn; The oil flow direction of the left turn is opposite to that of the right turn.

[0037] In the initial steering mode selection, When the front-wheel steering mode is selected, the first locking electromagnet 62 and the second locking electromagnet 73 are not energized; When the crab steering mode is selected, the second locking electromagnet 73 is first energized, and the third electromagnet 72 is energized t milliseconds after being energized; after T seconds, the second locking electromagnet 73 is de-energized, and the third electromagnet 72 is de-energized t milliseconds after being de-energized; When the all-wheel steering mode is selected, the second locking electromagnet 73 is first energized, and the second electromagnet 71 is energized t milliseconds after being energized; after T seconds, the second locking electromagnet 73 is de-energized, and the second electromagnet 71 is de-energized t milliseconds after being de-energized; When the rear-wheel steering mode is selected, the first locking electromagnet 62 and the second locking electromagnet 73 are first energized, and the first electromagnet 61 and the second electromagnet 71 are energized t milliseconds after being energized; after T seconds, the first locking electromagnet 62 and the second locking electromagnet 73 are de-energized, and the first electromagnet 61 and the second electromagnet 71 are de-energized t milliseconds after being de-energized; Among them, t ranges from 100 to 500, and T ranges from 1 to 3.

[0038] In this embodiment, t is taken as 200 and T is taken as 2.

[0039] During the switching process of the steering mode, the switching conditions need to be met, that is, X < 1° and Y < 1°.

[0040] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0041] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A telescopic forklift control system, comprising a steering gear assembly (3) connected to a hydraulic oil tank (2) via a working pump (1), and a front axle steering cylinder (4) and a rear axle steering cylinder (5) connected to the steering gear assembly (3) via a reversing valve (31) assembly, characterized in that: The steering valve assembly comprises a front axle steering valve (6) connected to the front axle steering cylinder (4) and a rear axle steering valve (7) connected to the rear axle steering cylinder (5); The front axle steering valve (6) is a two-position four-way solenoid valve and is provided with a first solenoid (61) for controlling the movement of the valve core and a first locking solenoid (62) for locking the position of the valve core; The rear axle steering valve (7) is a three-position four-way solenoid valve and is provided with a second solenoid (71) for controlling the movement of the valve core, a third solenoid (72) and a second locking solenoid (73) for locking the position of the valve core; The L port of the steering gear assembly (3) is connected to the P port of the rear axle steering valve (7), the R port is connected to the T port of the front axle steering valve (6), and the T port of the rear axle steering valve (7) is connected to the P port of the front axle steering valve (6).

2. The telescopic forklift control system according to claim 1, characterized in that: The steering gear assembly (3) comprises a reversing valve (31) whose valve core is moved by controlling the vehicle steering wheel, and a one-way valve (32) arranged on a main oil inlet pipeline between the reversing valve (31) and the steering valve assembly and an oil replenishment pipeline between the hydraulic oil tank (2), wherein an overflow valve (33) connected in parallel with the one-way valve (32) is arranged between the main oil inlet pipeline and the oil replenishment pipeline.

3. The telescopic forklift control system according to claim 1, characterized in that: Angle sensors are provided at the hinges between the front axle and the left and right front wheels, and at the hinges between the rear axle and the left and right rear wheels. The angle sensors are connected to the signals of the whole machine controller for monitoring the wheel angles.

4. The control method of a telescopic forklift control system according to any one of claims 1 to 3, characterized in that: Including front-wheel steering mode, crab steering mode, all-wheel steering mode and rear-wheel steering mode; During operation, when the front wheel steering angle X≥1° or the rear wheel steering angle Y≥1°, the correction mode is triggered; In the correction mode, there are two switching logics, namely, switching permission logic and switching prohibition logic. The specific switching logic is: Switch from crab steering mode to front-wheel steering mode or rear-wheel steering mode; Switch from all-wheel steering mode to front-wheel steering mode or rear-wheel steering mode; Switch from front-wheel steering mode to rear-wheel steering mode; Switch from rear-wheel steering mode to front-wheel steering mode; The specific logic of prohibiting switching is: When the driver operates the control panel to switch from crab steering mode to all-wheel steering mode, or from all-wheel steering mode to crab steering mode, or from front-wheel steering mode to crab steering mode, or from front-wheel steering mode to all-wheel steering mode, or from rear-wheel steering mode to crab steering mode, or from rear-wheel steering mode to all-wheel steering mode, an alarm is issued, the display screen prompts to make corrections first, and resets to the steering mode the vehicle was in before the switch.

5. The control method of the telescopic forklift control system according to claim 4, characterized in that: The front wheel steering mode is specifically: When the whole machine is switched to the front wheel steering mode, the hydraulic oil is distributed through the steering gear assembly (3) to the steering system, and the first electromagnet (61), the second electromagnet (71), the third electromagnet (72), the first locking electromagnet (62) and the second locking electromagnet (73) of the front axle steering valve (6) and the rear axle steering valve (7) are all in a power-off state; When the steering wheel is operated to turn right, the hydraulic oil is output from the oil port R of the steering gear assembly (3), and is transported to the oil port T of the front axle steering valve (6) through the pipeline. After passing through the front axle steering valve (6), the hydraulic oil is output from the oil port B of the front axle steering valve (6), and is transported to the oil port V1 of the front axle steering cylinder (4) through the pipeline, and the front axle steering cylinder (4) is actuated. The hydraulic oil is transported from the oil port V2 of the front axle steering cylinder (4) back to the oil port A of the front axle steering valve (6) through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve (6) through the pipeline to the oil port T of the rear axle steering valve (7). The oil port P and the oil port T of the rear axle steering valve (7) are connected. The hydraulic oil is connected from the oil port P of the rear axle steering valve (7) through the pipeline to the oil port L of the steering gear assembly (3), thereby completing the right turn. The left turn oil flow direction is opposite to that of the right turn oil flow direction.

6. The control method of the telescopic forklift control system according to claim 4, characterized in that: The crab steering mode is specifically: When the whole machine is switched to the crab steering mode, the hydraulic oil is distributed through the steering gear assembly (3) to the steering system, the first electromagnet (61) and the first locking electromagnet (62) of the front axle steering valve (6) and the second electromagnet (71) of the rear axle steering valve (7) are de-energized, and the third electromagnet (72) and the second locking electromagnet (73) of the rear axle steering valve (7) are energized; When the steering wheel is operated to turn right, the hydraulic oil is output from the oil port R of the steering gear assembly (3), and is transported to the oil port T of the front axle steering valve (6) through the pipeline. After passing through the front axle steering valve (6), the hydraulic oil is output from the oil port B of the front axle steering valve (6), and is transported to the oil port V1 of the front axle steering cylinder (4) through the pipeline, and the front axle steering cylinder (4) is actuated. The hydraulic oil is transported from the oil port V2 of the front axle steering cylinder (4) back to the oil port A of the front axle steering valve (6) through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve (6) through the pipeline to the oil port T of the rear axle steering valve (7). The oil port T of the rear axle steering valve (7) is connected to the oil port B, and the oil port P is connected to the oil port A. The hydraulic oil enters the oil port V2 of the rear axle steering cylinder (5) through the pipeline, and the rear axle steering cylinder (5) is actuated. The hydraulic oil is transported from the oil port V1 of the rear axle steering cylinder (5) back to the oil port A of the rear axle steering valve (7) through a pipeline, and the oil port P inside the rear axle steering valve (7) is connected to the oil port A. The hydraulic oil is connected from the oil port P of the rear axle steering valve (7) through a pipeline to the oil port L of the steering gear assembly (3), thereby completing the right turn. The left turn oil flow direction is opposite to that of the right turn oil flow direction.

7. The control method of the telescopic forklift control system according to claim 4, characterized in that: The all-wheel steering mode is specifically: When the whole machine is switched to the all-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly (3) to the steering system, the first electromagnet (61) and the first locking electromagnet (62) of the front axle steering valve (6) and the third electromagnet (72) of the rear axle steering valve (7) are powered off, and the second electromagnet (71) and the second locking electromagnet (73) of the rear axle steering valve (7) are powered on; When the steering wheel is operated to turn right, the hydraulic oil is output from the oil port R of the steering gear assembly (3), and is transported to the oil port T of the front axle steering valve (6) through the pipeline. After passing through the front axle steering valve (6), the hydraulic oil is output from the oil port B of the front axle steering valve (6), and is transported to the oil port V1 of the front axle steering cylinder (4) through the pipeline, and the front axle steering cylinder (4) is actuated. The hydraulic oil is transported from the oil port V2 of the front axle steering cylinder (4) back to the oil port A of the front axle steering valve (6) through the pipeline. At this time, the hydraulic oil is transported from the oil port P of the front axle steering valve (6) through the pipeline to the oil port T of the rear axle steering valve (7). The oil port T of the rear axle steering valve (7) is connected to the oil port A, and the oil port P is connected to the oil port B. The hydraulic oil enters the oil port V1 of the rear axle steering cylinder (5) through the pipeline, and the rear axle steering cylinder (5) is actuated. The hydraulic oil is transported from the oil port V2 of the rear axle steering cylinder (5) back to the oil port B of the rear axle steering valve (7) through a pipeline, and the oil port P in the rear axle steering valve (7) is connected to the oil port B. The hydraulic oil is connected from the oil port P of the rear axle steering valve (7) to the oil port L of the steering gear assembly (3) through a pipeline, thereby completing the right turn. The left turn oil flow direction is opposite to that of the right turn oil flow direction.

8. The control method of the telescopic forklift control system according to claim 4, characterized in that: The rear wheel steering mode is specifically: When the whole machine is switched to the rear-wheel steering mode, the hydraulic oil is distributed through the steering gear assembly (3) to the steering system, the first electromagnet (61) and the first locking electromagnet (62) of the front axle steering valve (6), the second electromagnet (71) and the second locking electromagnet valve of the rear axle steering valve (7) are all energized, and the third electromagnet (72) is de-energized; When the steering wheel is operated to turn right, the oil is transported to the oil port T of the front axle steering valve (6) through the pipeline, the oil port T of the front axle steering valve (6) is connected to the oil port P, and then transported to the oil port T of the rear axle steering valve (7) through the pipeline. At this time, the internal oil passage of the rear axle steering valve (7) is connected to the oil port T and the oil port A, and the oil port P is connected to the oil port B. The hydraulic oil enters the oil port V1 of the rear axle steering cylinder (5) through the pipeline connection, and the rear axle steering cylinder (5) is actuated; The hydraulic oil is transported from the oil port V2 of the rear axle steering cylinder (5) back to the oil port B of the front axle steering valve (6) through a pipeline, and the internal oil port P of the rear axle steering valve (7) is connected to the oil port B. The hydraulic oil is connected from the oil port P of the rear axle steering valve (7) to the oil port L of the steering gear assembly (3) through a pipeline, thereby completing the right turn. The left turn oil flow direction is opposite to that of the right turn oil flow direction.

9. The control method of the telescopic forklift control system according to claim 4, characterized in that: In the initial steering mode selection, When the front wheel steering mode is selected, the first locking electromagnet (62) and the second locking electromagnet (73) shall not be energized; When the crab steering mode is selected, the second locking electromagnet (73) is energized first, and the third electromagnet (72) is energized t milliseconds after being energized; after T seconds, the second locking electromagnet (73) is de-energized, and the third electromagnet (72) is de-energized t milliseconds after being de-energized; When the all-wheel steering mode is selected, the second locking electromagnet (73) is energized first, and t milliseconds after energization, the second electromagnet (71) is energized; after T seconds, the second locking electromagnet (73) is de-energized, and t milliseconds after de-energization, the second electromagnet (71) is de-energized; When the rear wheel steering mode is selected, the first locking electromagnet (62) and the second locking electromagnet (73) are powered first, and t milliseconds after being powered, the first electromagnet (61) and the second electromagnet (71) are powered; after T seconds, the first locking electromagnet (62) and the second locking electromagnet (73) are powered off, and t milliseconds after being powered off, the first electromagnet (61) and the second electromagnet (71) are powered off; Where t is between 100 and 500, and T is between 1 and 3.

10. The control method of the telescopic forklift control system according to claim 9, characterized in that: During the switching process of the steering mode, the switching conditions must be met, that is, X<1° and Y<1°.

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