Forklift automatic parking system and control method thereof

Abstract

The application discloses a forklift automatic parking system and a control method thereof, and belongs to the technical field of forklift parking control, and comprises a brake assembly which acts on an output shaft of a gearbox of the forklift and is used for performing locking or releasing actions on the output shaft; a control assembly which is electrically connected with the brake assembly, and the control assembly is electrically connected with an electronic accelerator pedal and a speed sensor of the forklift respectively; the forklift parking condition is recognized through the electronic accelerator pedal for collecting an accelerator state and the speed sensor for collecting a vehicle speed state, and the control assembly is used for completing logical judgment; the brake locking is automatically triggered through the recognition of the forklift parking condition, the driver does not need to manually operate a parking mechanism, the risk of vehicle sliding caused by the driver forgetting to operate the parking mechanism is avoided from the source, and the safety performance of forklift operation is improved.

Description

Technical Field

[0001] This invention relates to the field of forklift parking control technology, specifically to an automatic forklift parking system and its control method. Background Technology

[0002] As an industrial handling vehicle, the parking brake system is a key device for the safe operation of forklifts, and its reliability is directly related to the personal and property safety during operation.

[0003] Currently, internal combustion forklifts generally employ two parking brake methods: mechanical cable-operated parking brake and electronic switch-operated parking brake. Mechanical cable-operated parking brakes are activated by the driver pulling the handbrake, which, via a cable, presses the brake pads against the brake drum, achieving mechanical locking. Electronic switch-operated parking brakes are activated by the driver operating an electronic button, which controls the actuator via an electrical signal to complete the parking maneuver. Both methods rely on the driver's active operation to achieve parking braking.

[0004] The existing parking methods have shortcomings: after the forklift is parked, the driver must first put it in neutral and then operate the brake lever or electronic switch; if the driver is negligent and fails to follow the operating procedures, it may lead to accidents such as the forklift rolling away, which may cause significant safety hazards. Summary of the Invention

[0005] To address the problems mentioned in the background section, the present invention provides the following technical solution: An automatic parking system for an internal combustion forklift and its control method, comprising: A braking assembly that acts on the output shaft of the forklift gearbox to perform locking or releasing actions on the output shaft; A control component electrically connected to the braking component, and the control component electrically connected to the electronic throttle pedal and speed sensor of the forklift, respectively; The control component is configured to, when no throttle signal or speed signal is received, control the braking component to perform a locking action on the transmission output shaft; and when at least one of the throttle signal or speed signal is received, control the braking component to perform a releasing action on the transmission output shaft.

[0006] Furthermore, the braking assembly includes: A brake, which is located at the output shaft of the gearbox; The bleed valve has one end connected to the internal oil circuit of the gearbox and the other end connected to the brake. The bleed valve is used to regulate the oil chamber pressure in the brake. The vent valve is electrically connected to the control component.

[0007] Furthermore, the brake is a wet multi-disc brake.

[0008] Furthermore, the bleed valve is a normally closed solenoid valve, which connects the oil passage from the gearbox to the brake when energized, and closes the oil passage when de-energized.

[0009] Furthermore, the control component includes a signal processing module, a calculation module, and a comparison and judgment module; The signal processing module, whose input terminal is electrically connected to the electronic throttle pedal, is used to output throttle status signals; The arithmetic module, whose input terminal is electrically connected to the speed sensor, is used to output the vehicle speed signal; The comparison and judgment module has its input terminals electrically connected to the signal processing module and the arithmetic module, respectively, and is used to perform logical judgments based on the throttle status signal and the vehicle speed signal. Its output terminal is electrically connected to the braking component.

[0010] Furthermore, the comparison and judgment module is configured to control the braking component to perform a locking action when the throttle status signal indicates that the throttle opening is zero and the vehicle speed signal indicates that the vehicle speed is zero for a preset delay; otherwise, it controls the braking component to perform a releasing action.

[0011] Furthermore, the preset delay is no less than 1.5 seconds.

[0012] Furthermore, the computing module is also electrically connected to the instrument panel of the forklift to output vehicle speed information in real time; the signal processing module is also electrically connected to the engine of the forklift to output throttle status signals.

[0013] Furthermore, the control component also includes a power supply module for drawing power from an external power source and supplying power to the signal processing module, the arithmetic module, and the comparison and judgment module; when the external power supply is disconnected, the control component loses power, and the braking component performs a locking action.

[0014] Furthermore, an automatic parking control method for a forklift includes: Real-time reception of throttle and vehicle speed signals; When neither the throttle signal nor the vehicle speed signal is detected, the control braking component performs a locking action on the transmission output shaft. When at least one of the throttle signal or vehicle speed signal is detected, the control braking assembly performs a release action on the transmission output shaft.

[0015] The technical solution provided by this invention has the following advantages compared with the known prior art: This invention uses an electronic throttle pedal to collect throttle status and a speed sensor to collect vehicle speed status. The control components then perform logical judgments to identify the forklift's parking conditions and automatically trigger the brake lock. This eliminates the need for manual operation of the parking mechanism by the driver, fundamentally preventing the risk of the forklift rolling away due to the driver forgetting to operate the parking brake, thus improving the safety performance of forklift operations. Furthermore, the use of a normally closed vent valve combined with a wet multi-disc brake structure ensures that the system automatically triggers the parking lock when the vehicle loses power or the control components lose power, further enhancing the safety of the forklift after parking and avoiding the risk of loss of control due to power failure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 This is a schematic diagram illustrating the working principle of the control component of the present invention; Figure 2 This is a cross-sectional view of the internal structure of the braking assembly of the present invention; Figure 3 This is a planar schematic diagram of the speed sensor of the present invention; Figure 4 This is a plan view of the electronic throttle pedal of the present invention; Figure 5 This is a schematic diagram illustrating the electronic throttle pedal signal principle of the present invention.

[0018] Reference numerals: 1. Output shaft; 2. Brake; 21. Friction plate; 22. Steel plate; 23. Piston; 24. Spring. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] The present invention will be further described below with reference to embodiments.

[0021] An automatic parking system for forklifts is provided, which automatically applies the parking brake after the vehicle stops, without the driver actively performing the parking operation, to keep the vehicle in a stopped state and ensure the safety of personnel and the vehicle.

[0022] The aforementioned automatic parking system includes a braking component and a control component, wherein the control component is used to control the actuation of the braking component; such as Figure 2 As shown, the braking assembly is located at the output shaft 1 of the forklift's gearbox. Its actuator can directly act on the output shaft 1 to lock or release it. Since the gearbox output shaft 1 is connected to the forklift's front wheels via the main reducer, differential, and half-shafts, when the braking assembly locks the gearbox output shaft 1, the left and right front wheels of the forklift stop rotating synchronously, and the vehicle achieves parking braking. Conversely, when the braking assembly releases the gearbox output shaft 1, the front wheels can rotate freely, and the vehicle can drive normally.

[0023] By locking or releasing the gearbox output shaft 1 using the above braking components, the rotation and stopping of the forklift wheels are controlled, ultimately achieving overall vehicle start-stop control.

[0024] It should be noted that the term "output shaft" as used in this article refers to the rotating shaft in the transmission chain of the gearbox that is directly acted upon by the braking components. It is not limited to the final output shaft of the gearbox, but can also be a transfer shaft or connecting shaft that is connected to the output end of the gearbox. Hereinafter, it will be referred to as "output shaft".

[0025] The braking assembly specifically includes two brakes 2, such as Figure 2 As shown, they are respectively installed at both ends of the output shaft 1 of the gearbox. The brake 2 is preferably a wet multi-disc brake, which contains multiple alternatingly stacked friction pads 21 and steel plates 22. The friction pads 21 are splined onto the output shaft 1 and can rotate synchronously with the output shaft 1; the steel plates 22 are fixedly connected to the brake 2 housing and remain stationary. Both the friction pads 21 and steel plates 22 are completely immersed in oil, which lubricates and dissipates heat from the friction pads 21 and steel plates 22, ensuring that the brake 2 always maintains good working condition.

[0026] A brake piston 23 is provided on one side of the friction plate 21 group, and a strong spring 24 is provided behind the piston 23. The spring 24 always applies a thrust to the piston 23. This thrust is transmitted to the friction plate 21 through the piston 23, pressing the friction plate 21 and the steel plate 22 together. Through the gradually increasing friction force, the friction plate 21 gradually stops rotating, and finally the output shaft 1 is completely locked. At this time, the forklift is in the parking state.

[0027] When the parking brake needs to be released, pressurized oil is introduced into the brake chamber inside the brake caliper 2, causing the oil pressure to act on the end face of the piston 23 and generate a force opposite to the thrust of the spring 24. When the oil pressure force is greater than the thrust of the spring 24, the piston 23 is pushed and compresses the spring 24. The clamping force applied by the piston 23 to the friction plate 21 is then released, the friction plate 21 separates from the steel plate 22, the output shaft 1 resumes free rotation, and the parking brake is released.

[0028] A bleed valve is also installed on the gearbox housing. This valve is a regulating switch that controls the flow of hydraulic oil into the brake chamber of the brake 2. One end of the bleed valve is connected to the oil circuit inside the gearbox, and the other end is connected to the brake chamber of the brake 2 through an oil pipe. The bleed valve is also electrically connected to the control component. The electrical signal output by the control component controls its on / off state, thereby adjusting the oil pressure in the brake chamber of the brake 2, and thus completing the compression or release of the friction plate 21 by the piston 23.

[0029] The bleed valve is a normally closed solenoid valve, preferably a two-position three-way solenoid valve. In the initial state, the bleed valve is in the de-energized closed state, the passage from the internal oil circuit of the gearbox to the brake chamber of the brake 2 is cut off, the oil in the brake chamber is discharged through the bleed port, and the oil pressure drops. At this time, the piston 23 presses the friction plate 21 under the thrust of the spring 24, and the brake 2 remains in the parking state of locking the output shaft 1.

[0030] When the bleed valve is energized, the valve core switches the oil circuit, connecting the oil circuit from the transmission to brake 2. Pressurized oil from the transmission flows into the brake chamber of brake 2, building up oil pressure to push piston 23 and compress spring 24, thereby releasing the pressure on friction pad 21. This allows brake 2 to release output shaft 1, disengaging the parking brake and enabling normal vehicle operation. If the bleed valve unexpectedly loses power, the valve core resets, the connecting oil circuit closes again, the oil pressure in the brake chamber is released, brake 2 relocks output shaft 1, and parking is restored.

[0031] This design ensures that the braking components will automatically lock when the vehicle is turned off or the system experiences an unexpected power failure, eliminating the risk of parking failure and improving the overall reliability of the system.

[0032] like Figure 1 As shown, the control component is electrically connected to the aforementioned bleed valve, and is also electrically connected to the forklift's electronic throttle pedal and speed sensor. The control component is configured to, when no throttle signal or speed signal is received, control the braking component to perform a locking action on the gearbox output shaft 1; and when at least one of the throttle signal or speed signal is received, control the braking component to perform a releasing action on the gearbox output shaft 1.

[0033] The control components specifically include a signal processing module, a calculation module, a power supply module, and a comparison and judgment module. The input terminal of the signal processing module is electrically connected to the electronic throttle pedal and is used to output a throttle status signal. The input terminal of the calculation module is electrically connected to the speed sensor and is used to output a vehicle speed signal. The comparison and judgment module has its input terminals electrically connected to both the signal processing module and the calculation module, and is used to perform logical judgments based on the aforementioned throttle status signal and vehicle speed signal. Its output terminal is electrically connected to the aforementioned bleed valve.

[0034] It should be noted that, as Figure 5 As shown, the electronic throttle pedal adopts a dual-signal output mode. The signal processing module can simultaneously collect and verify two sets of signals to determine whether the two sets of signals are within their respective effective voltage windows and whether the ratio between them conforms to preset rules. If either set of signals exceeds the effective range or the ratio of the two signals is mismatched, the throttle signal is determined to be abnormal. The signal processing module sends the abnormal status to the comparison and judgment module, which outputs a parking control signal to control the bleed valve of the braking component to switch to the closed state to perform a locking action and prevent the vehicle from losing control due to throttle signal failure.

[0035] In addition, such as Figure 3 As shown, the speed sensor is a DC Hall effect proximity switch, mounted on the axle housing of the forklift drive axle. Inside the axle housing, a gear rotates with the drive wheel. When each tooth of the gear approaches the sensing end face of the speed sensor, an electrical pulse signal is generated inside the sensor. The processing module receives this pulse signal and calculates the actual vehicle speed based on the number of pulses per unit time, combined with preset tire diameter and wheel-side reduction ratio parameters. This speed parameter is displayed in real-time on the instrument panel and is also used to determine whether the vehicle is at zero speed, for use by the comparison and judgment module when executing the parking judgment logic.

[0036] The preset logic of the comparison and judgment module is as follows: when the throttle status signal indicates that the current throttle opening is zero and the vehicle speed signal indicates that the current vehicle speed is zero, and both states continue for a preset delay, the bleed valve is de-energized, thereby causing the brake 2 to lock the output shaft 1 and automatically complete the parking process; if at least one of the above two conditions is not met, that is, there is a throttle signal or the vehicle speed is not zero, the bleed valve is kept energized, the brake 2 maintains the released state of the output shaft 1, and the vehicle can drive normally.

[0037] The preset delay here is set to no less than 1.5 seconds, which can prevent the system from accidentally triggering the parking brake due to temporary release of the accelerator or brief coasting during vehicle operation, and ensure that the vehicle will not lock unexpectedly during normal driving.

[0038] The output of the computing module is also electrically connected to the forklift's instrument panel to send real-time vehicle speed information for display, allowing the driver to monitor the vehicle's speed at any time. The output of the signal processing module is also electrically connected to the forklift's engine to send the processed throttle status signal to the engine control unit.

[0039] The control unit also has a power module that draws power from the forklift's backup power supply. After internal voltage regulation and filtering, the power module provides a stable operating voltage for the signal processing module, the arithmetic module, and the comparison and judgment module.

[0040] When the external power supply is disconnected due to the key being turned off or other reasons, the power module stops supplying power, the entire control component loses power, the bleed valve is then de-energized and closed, the brake chamber of brake 2 leaks oil, spring 24 pushes piston 23 to press friction pad 21, causing the brake component to automatically perform a locking action, locking the gearbox output shaft 1, ensuring that the vehicle automatically enters the parking state when the power is off.

[0041] It should be noted that the aforementioned signal processing module, arithmetic module, and comparison and judgment module can all be implemented using conventional hardware circuits or software algorithms in this field. For example, the signal processing module can use an RC filter circuit and a window comparator to perform signal verification; the arithmetic module can use a counter chip or a timer module of a microcontroller to perform pulse counting and vehicle speed conversion; and the comparison and judgment module can be implemented using logic gate circuits or program judgment logic of a microcontroller. This article will not elaborate further on their specific internal circuit structures or program code.

[0042] An automatic parking control method for a forklift, executed by the aforementioned control component, specifically includes the following steps: Step 1: Receive throttle and vehicle speed signals in real time. The throttle signal comes from the electronic throttle pedal, and the vehicle speed signal comes from the speed sensor.

[0043] Step 2: When neither the throttle signal nor the vehicle speed signal is detected, the control component controls the braking component to lock the transmission output shaft, and the vehicle achieves parking brake.

[0044] Step 3: When at least one of the throttle signal or vehicle speed signal is detected, the control component controls the braking component to release the transmission output shaft, and the vehicle can drive normally.

[0045] Furthermore, in step two, if the state where neither the throttle signal nor the vehicle speed signal is detected continues for more than a preset delay time, the control component then controls the braking component to perform a locking action. The preset delay time is no less than 1.5 seconds, which is used to avoid accidental braking caused by momentary interruption of signals when the vehicle is driving on bumpy roads.

[0046] In addition, when the forklift loses power, the control components lose power, and the braking components automatically lock the output shaft of the gearbox, so that the vehicle automatically enters the parking state when the power is off.

[0047] Working principle: During normal forklift operation, when the driver depresses the electronic throttle pedal, the signal processing module of the control component detects the effective throttle opening signal. The comparison and judgment module outputs a control signal based on this signal, keeping the vent valve energized. Transmission pressurized oil enters the brake chamber of brake 2, pushing piston 23 to compress spring 24. At this time, friction plate 21 separates from steel plate 22, and transmission output shaft 1 remains free to rotate, allowing the vehicle to move normally. When the vehicle reaches the parking position, the driver releases the throttle pedal, reducing the throttle opening to zero. Due to inertia, the vehicle continues to coast, and the speed sensor continuously detects a non-zero speed signal. Therefore, the comparison and judgment module continues to control the forklift. The bleed valve remains energized, and brake 2 remains released until the vehicle comes to a complete stop and the vehicle speed signal becomes zero. At this point, both conditions are met simultaneously, and the preset delay is calculated. After the delay ends, the comparison and judgment module outputs a signal to de-energize the bleed valve, which cuts off the oil circuit. Spring 24 pushes piston 23 to press friction plate 21 and steel plate 22, locking the gearbox output shaft 1 and automatically completing parking. When the vehicle needs to start again, the driver presses the accelerator pedal. The signal processing module detects a valid throttle opening signal, and the comparison and judgment module immediately controls the bleed valve to be energized, connecting the oil circuit to establish oil pressure, releasing brake 2 from locking the output shaft 1, and the vehicle can start driving normally. The entire process does not require the driver to actively operate the parking brake mechanism; it is entirely executed automatically by the system. This simplifies the driver's operation and avoids the risk of the vehicle rolling due to the driver forgetting to engage the handbrake. At the same time, the system automatically locks the output shaft 1 in the event of power failure, engine shutdown, or other fault conditions, significantly improving the safety and reliability of parking the internal combustion forklift.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic parking system for forklifts, characterized in that, include: A braking assembly that acts on the output shaft of the forklift gearbox to perform locking or releasing actions on the output shaft; A control component electrically connected to the braking component, and the control component electrically connected to the electronic throttle pedal and speed sensor of the forklift, respectively; The control component is configured to, when no throttle signal or speed signal is received, control the braking component to perform a locking action on the transmission output shaft; and when at least one of the throttle signal or speed signal is received, control the braking component to perform a releasing action on the transmission output shaft.

2. The forklift automatic parking system according to claim 1, characterized in that, The braking assembly includes: A brake, which is located at the output shaft of the gearbox; The bleed valve has one end connected to the internal oil circuit of the gearbox and the other end connected to the brake. The bleed valve is used to regulate the oil chamber pressure in the brake. The vent valve is electrically connected to the control component.

3. The forklift automatic parking system according to claim 2, characterized in that, The brake is a wet multi-disc brake.

4. The forklift automatic parking system according to claim 3, characterized in that, The bleed valve is a normally closed solenoid valve, which connects the oil passage from the gearbox to the brake when energized, and closes the oil passage when de-energized.

5. The forklift automatic parking system according to claim 1, characterized in that, The control component includes a signal processing module, a calculation module, and a comparison and judgment module; The signal processing module, whose input terminal is electrically connected to the electronic throttle pedal, is used to output throttle status signals; The arithmetic module, whose input terminal is electrically connected to the speed sensor, is used to output the vehicle speed signal; The comparison and judgment module has its input terminals electrically connected to the signal processing module and the arithmetic module, respectively, and is used to perform logical judgments based on the throttle status signal and the vehicle speed signal. Its output terminal is electrically connected to the braking component.

6. The forklift automatic parking system according to claim 5, characterized in that, The comparison and judgment module is configured to control the braking component to perform a locking action when the throttle status signal indicates that the throttle opening is zero and the vehicle speed signal indicates that the vehicle speed is zero for a preset delay; otherwise, it controls the braking component to perform a releasing action.

7. The forklift automatic parking system according to claim 6, characterized in that, The preset delay is no less than 1.5 seconds.

8. The forklift automatic parking system according to claim 5, characterized in that, The computing module is also electrically connected to the instrument panel of the forklift to output vehicle speed information in real time; the signal processing module is also electrically connected to the engine of the forklift to output throttle status signals.

9. The forklift automatic parking system according to claim 5, characterized in that, The control component also includes a power supply module for drawing power from an external power source and supplying power to the signal processing module, the arithmetic module, and the comparison and judgment module; when the external power supply is disconnected, the control component loses power, and the braking component performs a locking action.

10. A method for controlling the automatic parking of a forklift, characterized in that, include: Real-time reception of throttle and vehicle speed signals; When neither the throttle signal nor the vehicle speed signal is detected, the control braking component performs a locking action on the transmission output shaft. When at least one of the throttle signal or vehicle speed signal is detected, the control braking assembly performs a release action on the transmission output shaft.

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