Aerial work platform in-situ bridge expansion system and control method thereof

Abstract

The invention discloses an aerial work platform in-situ bridge expansion control system and a control method thereof. The control system comprises a power assembly, a walking hydraulic system, a steering bridge expansion hydraulic system, a controller assembly and a frame assembly. The frame assembly comprises a frame body, a front supporting assembly, a rear supporting assembly and four supporting leg assemblies hinged to the frame body. The upper end of the front supporting assembly and the upper end of the rear supporting assembly are fixedly installed on the front side and the rear side of the frame body respectively. The front supporting assembly and the rear supporting assembly are of a telescopic structure. The front support assembly extends out to jack up the front part of the frame body, and the two front wheels leave the ground; the rear support assembly extends out to jack up the tail part of the frame body, and the two rear wheels are separated from the ground; the control method comprises three bridge expansion modes of off-ground, flat ground and obstacle crossing and bridge expansion. The device has the beneficial effects that the self-rotation backpressure of the motor can be reduced, and the resistance of the bridge expanding oil cylinder is reduced; and an energy-saving obstacle-crossing off-ground bridge expansion mode is added, and the bridge expansion scheme enables the whole machine to be more stable and the bridge expansion to be more accurate, and is not limited by space area conditions.

Description

Technical Field

[0001] This invention relates to a chassis system and control method for an aerial work platform, and particularly to an on-site bridge widening system and control method for an aerial work platform, belonging to the field of engineering vehicle technology. Background Technology

[0002] The axle expansion function of an aerial work platform refers to the technology that allows the chassis axles to expand and contract in width via a hydraulic system. During transport and travel, the chassis is in a narrower configuration to ensure maneuverability; during aerial work, the axle expansion increases the chassis width, thereby improving the overall operational stability of the machine. The axle expansion system typically consists of a frame, outriggers, and axle expansion cylinders. The four outriggers are hinged to the frame via pins, and one end of the axle expansion cylinder is connected to the frame, while the other end is connected to the outriggers. When the cylinder extends, it pushes the outriggers outward, increasing the outrigger span; when retracting, it closes the outriggers, reducing the overall width of the platform.

[0003] For aerial work platforms designed for high-speed applications, the chassis are typically equipped with outriggers to accommodate various operating conditions. Generally, the outriggers retract during transport or short-distance travel, and extend to provide greater support arm for stability during operation. Currently, the most common outrigger extension solutions are the "X-type" and "H-type" outriggers. However, these require continuous movement of the machine to extend, resulting in significant tire wear and potential issues with the outriggers failing to extend due to malfunctions in the travel system.

[0004] While in-situ axle widening techniques have emerged in the industry for "X-shaped axles," such as the in-situ axle widening chassis and aerial work platform disclosed in Chinese Patent CN115257233 A, this method widens the axle by pushing the wheel assembly and rotating it so that its rolling direction aligns with the swing tangent of the half-axle structure. During the swing, the wheel assembly rolls synchronously, thus widening the axle. However, this technique relies on a bypass valve to block high-pressure hydraulic fluid from entering the travel motor and releases the brakes, allowing the motor to rotate under external force. When widening the axle on uneven ground, relying solely on the widening cylinder can lead to insufficient power, making widening difficult or even impossible. Furthermore, asynchronous widening can cause the vehicle body to twist and tilt, resulting in poor widening performance. Additionally, due to the long motor connection lines and uneven road surfaces or the machine's center of gravity being far from its center of gravity, the adhesion on the motor side is low. During widening, the motor tires may not rotate, causing the tires to slip on the road surface, leading to tire wear and increased resistance during widening.

[0005] Chinese patent CN 119348341 A discloses a method and system for extending a vehicle chassis axle. The method includes a normal extension mode, an obstacle-encounter extension mode, a limit extension mode, and a free extension mode. In the normal extension mode, if an obstacle is encountered and the pressure of the extension cylinder increases beyond the system's set pressure, the system switches to the obstacle-encounter extension mode. After the wheels are swung, the pressure decreases, and the axle continues to extend. If the pressure does not decrease, the system switches to the limit extension mode. The free extension mode involves manual control of at least one wheel or axle via an operating panel. Automatic obstacle avoidance and successful axle extension within a limited area are achieved through individually controlled valve groups and coordinated control logic. This technical solution uses individual control of the four wheels or increases the pressure of the extension cylinders to achieve obstacle-encounter extension. However, this solution fails to fundamentally improve the obstacle-crossing and axle extension capability and requires higher pressure values ​​and larger extension cylinders, which reduces the overall reliability of the machine while increasing its cost and energy consumption.

[0006] When widening a bridge on the spot, the vehicles need to be in contact with the road surface and have a certain degree of road adhesion, which creates resistance and increases the energy consumption of the bridge widening process. Furthermore, when widening a bridge over obstacles, if the obstacle is large, even if the vehicle increases its driving force, it will not be able to widen the bridge over the obstacle, thus limiting the applicable conditions for bridge widening. Summary of the Invention

[0007] Purpose of the Invention: The purpose of this invention is to address the technical problems existing in the prior art by providing an on-site bridge widening system for aerial work platforms and its control method. This system can completely drain the oil from the high-pressure port of the self-rotating motor back to the hydraulic oil tank during the on-site bridge widening process, thereby reducing the motor's self-rotation back pressure, decreasing the resistance of the bridge widening cylinder, and reducing the overall energy consumption of the machine. Simultaneously, due to the low motor return oil back pressure, the motor can still self-rotate when tire adhesion is low to prevent dragging and affecting the bridge widening effect. Furthermore, an energy-saving obstacle-crossing off-ground bridge widening mode is added. When the machine is located in areas with poor road conditions or limited space, an off-ground bridge widening mode with the tires off the ground can be used. This bridge widening scheme makes the machine more stable, the bridge widening more precise, and is not limited by spatial conditions.

[0008] Technical solution: A control system for on-site bridge expansion of an aerial work platform, comprising a powertrain, a travel hydraulic system, a steering bridge expansion hydraulic system, a controller assembly, and a frame assembly. The powertrain provides high-pressure hydraulic fluid to the travel hydraulic system and the steering bridge expansion hydraulic system. The controller assembly is connected to the travel hydraulic system and the steering bridge expansion hydraulic system via signals. The travel hydraulic system and the steering bridge expansion hydraulic system are mounted on the frame assembly and drive the actuators of the frame assembly to work.

[0009] The powertrain includes a power unit, a travel pump, and a steering expansion pump. The power output terminal of the power unit is simultaneously connected to the travel pump and the steering expansion pump.

[0010] The walking hydraulic system includes a walking control valve and four walking motors, and the walking pump drives the four walking motors respectively through the walking control valve;

[0011] The steering bridge expansion hydraulic system includes a steering bridge expansion control valve, a front support cylinder, a rear support cylinder, four steering cylinders, and four expansion cylinders; the steering bridge expansion pump controls the front support cylinder, the rear support cylinder, the four steering cylinders, and the four expansion cylinders respectively through the steering bridge expansion control valve.

[0012] The controller assembly is connected to the travel control valve and the steering bridge control valve via signals, respectively.

[0013] The frame assembly includes a frame body, a front support assembly, a rear support assembly, and four support leg assemblies hinged to the frame body. The upper ends of the front support assembly and the rear support assembly are respectively fixedly installed on the front and rear sides of the frame body.

[0014] The front support assembly and the rear support assembly are telescopic structures with a front support cylinder and a rear support cylinder inside; the front support cylinder extends to lift the front part of the frame body, and the two front wheels are off the ground; the rear support cylinder extends to lift the rear part of the frame body, and the two rear wheels are off the ground.

[0015] The present invention has a front support assembly and a rear support assembly installed on the front and rear sides of the vehicle frame body, respectively, and the extension and retraction of the front support cylinder and the rear support cylinder are controlled by the steering bridge expansion control valve.

[0016] When the machine is located in an area with poor road conditions or limited space, the front and rear supports lift the front and rear of the chassis body, respectively. Once the front wheels are off the ground, the steering axle widening control valve controls the two front axle widening cylinders to complete the widening process. Then, the front support assembly retracts the front wheels to complete the widening before the machine lands. Similarly, the rear axle is widened before landing. Because the center of gravity of the aerial work platform is prone to shifting, the front and rear supports cannot simultaneously lift all four wheels off the ground. Since the wheels are off the ground, they no longer contact the ground during the widening process, eliminating the need for driving force and reducing friction between the wheels and the ground. This reduces the resistance of the widening cylinders, achieving energy savings. With the wheels off the ground, the widening process is no longer limited by spatial conditions, making the widening process more stable and the widening angle more precise.

[0017] In a preferred embodiment, in order to achieve automated control of the travel pump and ensure the normal operation of the travel hydraulic system, the travel pump includes a travel pump solenoid control valve and a replenishing pump;

[0018] The solenoid control valve for the travel pump is a three-position four-way solenoid valve. Electromagnets Y9 and Y10, which are connected to the controller assembly, are respectively installed on both sides of the solenoid control valve. When neither electromagnet Y9 nor electromagnet Y10 is energized, the solenoid control valve for the travel pump is in the neutral position and the travel pump flow is zero. When either electromagnet Y9 or electromagnet Y10 is energized, the travel pump starts to supply oil, and when either electromagnet Y9 or electromagnet Y10 is energized, the direction of oil supply by the travel pump is opposite.

[0019] The replenishing pump is driven by a power unit and operates synchronously with the traveling pump. The oil inlet of the replenishing pump is connected to the oil tank, and the oil outlet of the replenishing pump is connected to the traveling hydraulic system.

[0020] The solenoid control valve of the travel pump controls the switch and flow direction of the travel pump oil supply. The replenishing pump provides power to the control oil circuit of the travel hydraulic system, continuously replenishing the leaked oil of the entire travel system, and can also replace hot and cold oil to improve heat dissipation performance.

[0021] In a preferred embodiment, in order to achieve uniform flow distribution and improve the overall driving force, the walking pump drives four walking motors respectively through a walking control valve;

[0022] The travel control valve includes a first diversion and combination valve, a second diversion and combination valve, and a third diversion and combination valve. The two front travel motors and the two rear travel motors merge and are respectively connected to the diversion port of the first diversion and combination valve. The combination port of the first diversion and combination valve is connected to the A oil port of the travel pump.

[0023] The other oil ports of the left and right rear travel motors are respectively connected to the diversion ports of the second diversion and combiner valve, and the combiner port of the second diversion and combiner valve is connected to the B oil port of the travel pump.

[0024] The other oil ports of the two left and right front travel motors are connected to the diversion ports of the third diversion and combiner valve, and the combiner port of the third diversion and combiner valve is connected to the B oil port of the travel pump.

[0025] The first flow divider valve ensures that the sum of the flow rates of the two front travel motors is equal to the sum of the flow rates of the two rear travel motors. The second flow divider valve ensures that the flow rates of the two rear travel motors are equal. The third flow divider valve ensures that the flow rates of the two front travel motors are equal. The combined use of these three flow divider valves ensures that the oil supplied by the travel pump is evenly distributed to the four travel motors. This invention drives four travel motors with one travel pump, and ensures that the flow rates of the four travel motors are equal through the first, second, and third flow divider valves. This enables synchronous movement of the four motors and also improves the overall driving force of the machine.

[0026] In a preferred embodiment, to reduce the back pressure of the travel motor's self-rotation, decrease the resistance of the expansion cylinder, and reduce the overall energy consumption of the machine, a three-way shuttle valve is connected in parallel at both ends of each of the four travel motors. The two inlets of each three-way shuttle valve are connected to the inlet and outlet ports of the travel motors, respectively, and the outlet port of the three-way shuttle valve is connected to the oil tank. A two-position, two-way, two-way shut-off solenoid valve is installed on the oil line between the outlet port of the three-way shuttle valve and the oil tank.

[0027] The electromagnet Y1 of the two-position two-way bidirectional shut-off solenoid valve connected to the left rear travel motor is connected to the signal of the controller assembly.

[0028] The electromagnet Y2 of the two-position two-way bidirectional shut-off solenoid valve connected to the right rear travel motor is connected to the signal of the controller assembly.

[0029] The electromagnet Y3 of the two-position two-way bidirectional shut-off solenoid valve connected to the left front travel motor is connected to the signal of the controller assembly.

[0030] The electromagnet Y4 of the two-position two-way bidirectional shut-off solenoid valve connected to the right front travel motor is connected to the controller assembly signal.

[0031] This invention can discharge all the oil from the high-pressure port of the self-rotating travel motor back to the hydraulic oil tank through a three-way shuttle valve and a two-position two-way bidirectional shut-off solenoid valve during the on-site bridge expansion process. This reduces the back pressure of the self-rotating travel motor, reduces the resistance of the bridge expansion cylinder, and reduces the energy consumption of the whole machine. At the same time, because the back pressure of the travel motor is small, when the tire adhesion is small, the travel motor can also self-rotate to prevent dragging and affecting the bridge expansion effect.

[0032] In a preferred embodiment, to further improve the working efficiency of the travel motors, all four travel motors are variable displacement motors. The control oil circuit of each travel motor is equipped with an electromagnetic directional valve, which has an electromagnet Y8 connected to the controller assembly. The oil supply pump provides control oil to the control oil circuit of the travel motors via the electromagnetic directional valve to control the motor's displacement. The electromagnetic directional valve connects the control oil circuit of the travel motors to the oil tank. When high torque and low speed are required, the controller assembly controls the electromagnetic directional valve via electromagnet Y8 to control the travel motor's displacement; simultaneously, it can also achieve switching between low torque and high speed.

[0033] In a preferred embodiment, in order to achieve separate braking control of the front and rear travel motors, each of the four travel motors is equipped with a hydraulic brake; a rear brake solenoid control valve is provided on the control oil circuit of the hydraulic brake of the two travel motors on the rear side of the machine, and the rear brake solenoid control valve is equipped with an electromagnet Y7 that is signal-connected to the controller assembly.

[0034] The control oil circuit of the hydraulic brake of the two travel motors on the front side of the machine is equipped with a front brake solenoid control valve, and the front brake solenoid control valve is equipped with an electromagnet Y6 that is connected to the controller assembly.

[0035] The oil replenishment pump provides control oil that is connected to the control oil circuit of the hydraulic brake of the travel motor through the rear brake solenoid control valve and the front brake solenoid control valve. The controller assembly controls the hydraulic brake of the rear travel motor and the hydraulic brake of the front travel motor respectively through electromagnets Y7 and Y6.

[0036] When it is necessary to control the front travel motor or the rear travel motor separately, the controller assembly controls the rear brake solenoid control valve or the front brake solenoid control valve through electromagnet Y7 or electromagnet Y6, thereby releasing the brake of the corresponding front travel motor or the rear travel motor, and thus realizing the separate control of the front and rear travel motors.

[0037] In a preferred embodiment, to enable free rotation of the four wheels, the travel control valve is equipped with a bidirectional shut-off solenoid valve connecting the inlet and outlet oil ports of the travel pump; the bidirectional shut-off solenoid valve is equipped with an electromagnet Y5 connected to the controller assembly via a signal connection. When the controller assembly energizes the electromagnet Y5, the bidirectional shut-off solenoid valve connects the oil passage between the inlet and outlet oil ports of the travel pump, and simultaneously connects the oil passages between the inlet and outlet oil ports of the four travel motors. High-pressure oil no longer enters the four travel motors, and the four travel motors can rotate freely.

[0038] A control method for an on-site bridge expansion control system for aerial work platforms, the on-site bridge expansion control method including an off-ground bridge expansion mode,

[0039] The control method for the off-ground bridge expansion mode is as follows:

[0040] When the bridge is extended off the ground, neither electromagnets Y9 nor Y10 of the traveling pump should be energized.

[0041] Step 1: Front axle expansion, controller assembly controls the solenoid Y7 of the rear brake solenoid control valve to de-energize, and the two rear travel motors maintain braking.

[0042] The controller assembly controls the steering expansion pump to supply oil to the rodless chamber of the forward support cylinder through the steering expansion control valve, and the front support assembly extends out of the front end of the frame assembly, raising the front support leg assembly off the ground.

[0043] The steering expansion pump supplies oil to the rodless chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until it reaches the set value of the controller assembly, at which point the steering expansion pump stops supplying oil to the rodless chambers of the two front expansion cylinders.

[0044] The controller assembly controls the steering expansion pump to supply oil to the rod chamber of the forward support cylinder through the steering expansion control valve. The front support assembly retracts, the front end of the frame assembly falls back, the front outrigger assembly touches the ground, and the front support assembly retracts to its initial state, completing the front axle expansion.

[0045] Step 2: After the rear axle is expanded, the electromagnet Y6 of the controller assembly controlling the front brake solenoid valve is de-energized, and the two front travel motors remain braked.

[0046] The controller assembly controls the steering expansion pump to supply oil to the rodless chamber of the rear support cylinder through the steering expansion control valve, and the rear support assembly extends out of the rear of the frame assembly, raising the rear support leg assembly off the ground.

[0047] The steering expansion pump supplies oil to the rodless chambers of the two rear expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until it reaches the set value of the controller assembly, at which point the steering expansion pump stops supplying oil to the rodless chambers of the two rear expansion cylinders.

[0048] The controller assembly controls the steering expansion pump to supply oil to the rod chamber of the rear support cylinder through the steering expansion control valve. After the rear support assembly retracts and the rear of the frame assembly falls back, the outrigger assembly touches the ground. The rear support assembly retracts to its initial state, completing the front axle expansion.

[0049] Step 3: Rear axle retraction. The rear support assembly first supports the rear outrigger assembly, and the two rear axle expansion cylinders retract. After the rear outrigger assembly completes the retraction, the rear support assembly retracts its tail and the outrigger assembly touches the ground. The rear support assembly retracts to its initial state.

[0050] Step 4: Front axle retraction. The front support assembly first supports the front outrigger assembly, and the two front axle expansion cylinders retract. After the front outrigger assembly completes the retraction, the front support assembly retracts and the front outrigger assembly lands on the ground. The front support assembly retracts to its initial state.

[0051] The order of operations and the number of steps in this invention can be adjusted according to the actual situation. For example, only the front axle can be expanded or only the rear axle can be expanded, or the front axle can be retracted first and then the rear axle can be retracted. The angles of expanding and retracting the axle can also be adjusted as needed.

[0052] This invention uses a front support assembly and a rear support assembly to lift the front and rear of the vehicle frame. Once the front wheels are lifted off the ground, the steering axle widening control valve controls two front axle widening cylinders to complete the axle widening process. Then, the front support assembly retracts the front wheels to complete the axle widening before the vehicle lands. Similarly, the rear axle is widened before landing. Because the center of gravity of the aerial work platform is prone to shifting, the front and rear support assemblies cannot simultaneously lift all four wheels off the ground. Since the wheels are off the ground, they no longer contact the ground during the axle widening process, eliminating the need for driving force and reducing friction between the wheels and the ground. This reduces the resistance of the axle widening cylinders, achieving energy savings. With the wheels off the ground, the axle widening process is no longer limited by spatial constraints, making the axle widening process more stable and the widening angle more precise.

[0053] Preferred options include, to improve the efficiency of on-site bridge widening and enrich the on-site bridge widening modes, control methods for on-site bridge widening include the level ground bridge widening mode.

[0054] When the working ground is flat, the flat ground bridge expansion mode can be used. The control method for the flat ground bridge expansion mode is as follows:

[0055] When expanding the bridge on level ground, the solenoid Y5 of the bidirectional shut-off solenoid valve is energized during both the expansion and retraction processes, while the solenoid Y8 of the solenoid directional valve is de-energized; the solenoids Y9 and Y10 of the traveling pump are not energized.

[0056] Step 1: Front axle expansion. The controller assembly controls the front brake solenoid control valve solenoid Y6 to be energized, while the rear brake solenoid control valve solenoid Y7 is de-energized, releasing the brakes of the two front travel motors, while keeping the brakes on the two rear travel motors.

[0057] The steering expansion pump supplies oil to the rod chamber of the steering cylinder of the two front outrigger assemblies. The steering cylinder begins to retract, and the steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly.

[0058] When the tire reaches the set angle of the controller assembly, the steering cylinder stops supplying oil, and the solenoids Y3 and Y4 of the two-position two-way bidirectional shut-off solenoid valve are energized. The two oil ports of the front travel motor are connected to the oil tank through the three-way shuttle valve and the two-position two-way bidirectional shut-off solenoid valve, and the front travel motor can rotate freely.

[0059] The steering expansion pump supplies oil to the rodless chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until the set value of the controller assembly is reached.

[0060] When the bridge expansion angle reaches the set value angle of the controller assembly, the steering bridge expansion pump stops supplying oil to the rodless chamber of the two front bridge expansion cylinders, and the steering bridge expansion pump supplies oil to the rodless chamber of the two front steering cylinders until the tire angle reaches the initial value. Then, the two-position two-way bidirectional shut-off solenoid valves solenoid Y3 and solenoid Y4 are de-energized, and the front brake solenoid control valve solenoid Y6 is de-energized, thus completing the front axle expansion.

[0061] Step 2: Rear axle expansion. The controller assembly controls the rear brake solenoid control valve solenoid Y7 to be energized, while the front brake solenoid control valve solenoid Y6 is de-energized, releasing the brakes of the two rear travel motors, while the two front travel motors remain braked.

[0062] The steering expansion pump supplies oil to the rod chambers of the two rear steering cylinders, and the aforementioned steering cylinders begin to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly.

[0063] When the tire reaches the set angle of the controller assembly, the steering cylinder stops supplying oil, and the solenoids Y1 and Y2 of the two-position two-way bidirectional shut-off solenoid valve are energized. The two oil ports of the rear travel motor are connected to the oil tank through the three-way shuttle valve and the two-position two-way bidirectional shut-off solenoid valve, and the front travel motor can rotate freely.

[0064] The steering expansion pump supplies oil to the rodless chambers of the two rear expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until the set value of the controller assembly is reached.

[0065] When the bridge expansion angle reaches the set value angle of the controller assembly, the steering bridge expansion pump stops supplying oil to the rodless chamber of the rear bridge expansion cylinder, and the steering bridge expansion pump supplies oil to the rodless chamber of the rear steering cylinder until the tire angle reaches the initial value. Electromagnets Y1, Y2, Y5 and Y7 are de-energized, and the bridge expansion is completed.

[0066] Step 3: Rear axle retraction, the method is the same as in Step 2. The steering expansion pump supplies oil to the rod chamber of the two rear expansion cylinders, and the above expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until the set value of the controller assembly is reached.

[0067] The tire's steering angle returns to its initial value, electromagnets Y1, Y2, Y5, and Y7 are de-energized, and the rear axle retracts.

[0068] Step 4: Retract the front axle, using the same method as in Step 1.

[0069] The steering expansion pump supplies oil to the rod chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until the set value of the controller assembly is reached.

[0070] The tire's steering angle returns to its initial value, and electromagnets Y3, Y4, Y5, and Y6 are de-energized, completing the front axle retraction.

[0071] In the flat ground bridge expansion mode, the bridge expansion is completed by simply pushing the outrigger assembly with the bridge expansion cylinder. During the flat ground bridge expansion process, the oil from the high-pressure port of the self-rotating travel motor is discharged back to the hydraulic oil tank through the three-way shuttle valve and the two-position two-way bidirectional shut-off solenoid valve. This reduces the back pressure of the self-rotating travel motor, reduces the resistance of the bridge expansion cylinder, and reduces the energy consumption of the whole machine. At the same time, because the back pressure of the travel motor is small, when the tire adhesion is small, the travel motor can also rotate to prevent dragging and affect the bridge expansion effect.

[0072] Preferred options include, to improve the efficiency of on-site bridge widening and enrich the on-site bridge widening modes, the control methods for on-site bridge widening include obstacle-crossing bridge widening modes.

[0073] When the working ground is uneven or sloping, the obstacle-crossing and bridge-expanding mode can be used. The control method for the obstacle-crossing and bridge-expanding mode is as follows:

[0074] When crossing obstacles and expanding the bridge, the electromagnet Y5 of the bidirectional shut-off solenoid valve must not be energized during the expansion and retraction of the bridge; at the same time, electromagnets Y1, Y2, Y3 and Y4 must also not be energized.

[0075] Step 1: Front axle expansion. The controller assembly controls the front brake solenoid control valve solenoid Y6 to be energized, while the rear brake solenoid control valve solenoid Y7 is de-energized, releasing the brakes of the two front travel motors, while keeping the brakes on the two rear travel motors.

[0076] The steering expansion pump supplies oil to the rod chamber of the front steering cylinder, and the steering cylinder begins to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly.

[0077] When the tire reaches the set angle of the controller assembly, the steering cylinder stops supplying oil, the solenoid Y8 of the solenoid reversing valve is energized, and at the same time the solenoid Y10 of the travel pump is energized. The travel pump supplies oil to the two travel motors on the front side, and the steering expansion pump supplies oil to the rodless chamber of the front expansion cylinder. The aforementioned expansion cylinder begins to extend, and the expansion angle sensor monitors the angle of the front outrigger assembly in real time until it reaches the set value of the controller assembly.

[0078] When the bridge expansion angle reaches the set angle of the controller assembly, the solenoid Y8 of the electromagnetic reversing valve is de-energized, and at the same time the solenoid Y10 of the travel pump is de-energized, and the travel pump stops supplying oil to the travel motor; the steering bridge expansion pump stops supplying oil to the rodless chamber of the front bridge expansion cylinder, and the steering bridge expansion pump feeds oil into the rodless chamber of the forward steering cylinder until the tire angle reaches the initial value. Finally, the solenoid Y6 of the front brake electromagnetic control valve is de-energized, and the front axle expansion is completed.

[0079] Step 2: Expand the rear axle, release the brake on the rear travel motor, and keep the brake on the front travel motor; rotate the two rear tires to the set value of the controller assembly.

[0080] When the solenoid Y8 of the electromagnetic reversing valve is energized, the solenoid Y9 of the travel pump is also energized. The travel pump supplies oil to the rear travel motor, and the steering expansion pump supplies oil to the rodless chamber of the rear expansion cylinder. The aforementioned expansion cylinder begins to extend. The expansion angle sensor monitors the angle of the rear outrigger assembly in real time until it reaches the set value of the controller assembly. The travel pump stops supplying oil to the rear travel motor. The steering expansion pump stops supplying oil to the rodless chamber of the rear expansion cylinder. The tire angle returns to its initial value. Finally, the solenoid Y7 of the rear brake solenoid control valve is de-energized, and the rear axle expansion is completed.

[0081] Step 3: Retract the rear axle. The method is the same as in Step 2. The steering expansion pump supplies oil to the rod chamber of the rear expansion cylinder, and the rear expansion cylinder begins to retract. After the rear axle is retracted, the rear axle is successfully retracted.

[0082] Step 4: Front axle retraction. The method is the same as in Step 1. The steering expansion pump supplies oil to the rod chamber of the front expansion cylinder, and the front expansion cylinder begins to retract, completing the front axle retraction.

[0083] The obstacle-crossing and bridge-widening mode combines the thrust of the bridge-widening cylinder and the driving force of the travel motor to complete the bridge widening, thus improving the ability to widen the bridge on the spot.

[0084] Beneficial effects: This invention can drain all the oil from the high-pressure port of the self-rotating motor back to the hydraulic oil tank during the on-site bridge widening process, thereby reducing the back pressure of the motor's self-rotation, reducing the resistance of the bridge widening cylinder, and reducing the energy consumption of the whole machine. At the same time, because the back pressure of the motor's return oil is small, the motor can also self-rotate to prevent dragging and affecting the bridge widening effect when the tire adhesion is small. It also adds an energy-saving obstacle-crossing off-ground bridge widening mode. When the whole machine is located in an area with poor road conditions or limited space, the off-ground bridge widening mode with the tires off the ground can be used. This bridge widening scheme makes the whole machine more stable, the bridge widening more accurate, and is not limited by the spatial conditions. Attached Figure Description

[0085] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0086] Figure 1 This is a hydraulic schematic diagram of the present invention;

[0087] Figure 2 This is a schematic diagram of the frame assembly of the present invention;

[0088] Figure 3 This is a schematic diagram of the structure of the front and rear support assembly in its retracted state.

[0089] Figure 4 This is a schematic diagram of the front support assembly of the present invention in its ground-supported state;

[0090] Figure 5 This is a schematic diagram of the rear support assembly of the present invention in its ground-supported state;

[0091] Figure 6 This is a schematic diagram of the electrical control principle of the present invention. Detailed Implementation

[0092] 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 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 are within the scope of protection of the present invention.

[0093] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0094] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0095] like Figure 1-5 As shown, an on-site bridge-expanding control system for an aerial work platform includes a powertrain 1, a travel hydraulic system 2, a steering bridge-expanding hydraulic system 3, a controller assembly 4, and a frame assembly 5. The powertrain 1 provides high-pressure hydraulic fluid to the travel hydraulic system 2 and the steering bridge-expanding hydraulic system 3, respectively. The controller assembly 4 is connected to the travel hydraulic system 2 and the steering bridge-expanding hydraulic system 3 by signals. The travel hydraulic system 2 and the steering bridge-expanding hydraulic system 3 are mounted on the frame assembly 5 and drive the actuators of the frame assembly 5 to work.

[0096] The powertrain 1 includes a power unit 11, a travel pump 12 and a steering expansion pump 13, and the power output end of the power unit 11 is simultaneously connected to the travel pump 12 and the steering expansion pump 13.

[0097] The walking hydraulic system 2 includes a walking control valve 21 and four walking motors. The walking pump 12 drives the four walking motors respectively through the walking control valve 21.

[0098] The steering bridge expansion hydraulic system 3 includes a steering bridge expansion control valve 31, a front support cylinder 32, a rear support cylinder 33, four steering cylinders, and four expansion cylinders; the steering bridge expansion pump 13 controls the front support cylinder 32, the rear support cylinder 33, the four steering cylinders, and the four expansion cylinders respectively through the steering bridge expansion control valve 31.

[0099] The controller assembly 4 is connected to the travel control valve 21 and the steering bridge control valve 31 via signals, respectively.

[0100] The frame assembly 5 includes a frame body 51, a front support assembly 52, a rear support assembly 53, and four support leg assemblies hinged to the frame body 51. The upper ends of the front support assembly 52 and the rear support assembly 53 are respectively fixedly installed on the front and rear sides of the frame body 51.

[0101] The front support assembly 52 and the rear support assembly 53 are telescopic structures with a front support cylinder 32 and a rear support cylinder 33 inside. The front support cylinder 32 extends to lift the front of the frame body 51, and the two front wheels are off the ground. The rear support cylinder 33 extends to lift the rear of the frame body 51, and the two rear wheels are off the ground.

[0102] The present invention has a front support assembly 52 and a rear support assembly 53 installed on the front and rear sides of the frame body 51, respectively, and the extension and retraction of the front support cylinder 32 and the rear support cylinder 33 are controlled by the steering bridge expansion control valve 31.

[0103] When the machine is located in an area with poor road conditions or limited space, the front and rear of the frame body 51 are lifted by the front support assembly 52 and the rear support assembly 53, respectively. After the front wheels of the frame body 51 are lifted off the ground, the steering axle widening control valve 31 controls the two front axle widening cylinders to complete the axle widening. Then, the front support assembly 52 retracts the front wheels to complete the axle widening and lands on the ground. Similarly, the rear axle is widened and lands on the ground. Because the center of gravity of the aerial work platform is prone to shift, the front support assembly 52 and the rear support assembly 53 cannot lift all four wheels of the machine off the ground simultaneously. Since the wheels are off the ground, they are no longer in contact with the ground during the axle widening process, so the wheels do not need to provide driving force and the friction between the wheels and the ground is reduced. This reduces the resistance of the axle widening cylinders during the axle widening process, achieving the effect of saving energy and reducing consumption. After the wheels are off the ground, the axle widening is no longer limited by the spatial conditions, making the axle widening process of the whole machine more stable and the widening angle more precise.

[0104] like Figure 1 As shown, in order to achieve automated control of the travel pump 12 and ensure the normal operation of the travel hydraulic system 2, the travel pump 12 includes a travel pump solenoid control valve 121 and a replenishing pump 122.

[0105] The solenoid control valve 121 of the travel pump is a three-position four-way solenoid valve. Electromagnets Y9 and Y10, which are connected to the controller assembly 4, are respectively provided on both sides of the solenoid control valve 121. When neither electromagnet Y9 nor electromagnet Y10 is energized, the solenoid control valve 121 of the travel pump is in the middle position and the flow of the travel pump 12 is zero. When one of the electromagnets Y9 and Y10 is energized, the travel pump 12 starts to supply oil, and when either electromagnet Y9 or electromagnet Y10 is energized, the oil supply direction of the travel pump 12 is opposite.

[0106] The replenishing pump 122 is driven by the power unit 11 and operates synchronously with the walking pump 12. The oil inlet of the replenishing pump 122 is connected to the oil tank, and the oil outlet of the replenishing pump 122 is connected to the walking hydraulic system 2.

[0107] The solenoid control valve 121 of the walking pump controls the oil supply switch and flow direction of the walking pump 12. The replenishing pump 122 provides power to the control oil circuit of the walking hydraulic system 2, continuously replenishing the leaked oil of the entire walking system, and also realizing the replacement of hot and cold oil to improve heat dissipation performance.

[0108] In order to achieve uniform flow distribution and improve the overall driving force, the walking pump 12 drives four walking motors respectively through the walking control valve 21;

[0109] The travel control valve 21 includes a first diversion and combination valve 211, a second diversion and combination valve 212, and a third diversion and combination valve 213. The two front travel motors and the two rear travel motors merge and are respectively connected to the diversion port of the first diversion and combination valve 211. The combination port of the first diversion and combination valve 211 is connected to the A oil port of the travel pump 12.

[0110] The other oil ports of the left and right rear travel motors are respectively connected to the diversion port of the second diversion and combination valve 212, and the combination port of the second diversion and combination valve 212 is connected to the B oil port of the travel pump 12.

[0111] The other oil ports of the two left and right front travel motors are connected to the diversion ports of the third diversion and merging valve 213, and the merging port of the third diversion and merging valve 213 is connected to the B oil port of the travel pump 12.

[0112] The first diversion and combiner valve 211 ensures that the sum of the flow rates of the two front travel motors is equal to the sum of the flow rates of the two rear travel motors. The second diversion and combiner valve 212 ensures that the flow rates of the two rear travel motors are equal. The third diversion and combiner valve 213 ensures that the flow rates of the two front travel motors are equal. The combined use of these three diversion and combiner valves ensures that the oil supplied by the travel pump 12 is evenly distributed to the four travel motors. This invention drives four travel motors with one travel pump 12, and ensures that the flow rates of the four travel motors are equal through the first, second, and third diversion and combiner valves 211, 212, and 213. This enables synchronous movement of the four motors and improves the overall driving force of the machine.

[0113] To reduce the back pressure of the travel motor's self-rotation, decrease the resistance of the expanded bridge cylinder, and reduce the overall energy consumption of the machine, three-way shuttle valves 214 are connected in parallel at both ends of the four travel motors. The two oil inlets of each three-way shuttle valve 214 are connected to the oil inlet and outlet of the travel motor, respectively, and the oil outlet of each three-way shuttle valve 214 is connected to the oil tank. A two-position, two-way, two-way, bidirectional shut-off solenoid valve 215 is installed on the oil line between the oil outlet of the three-way shuttle valve 214 and the oil tank.

[0114] The electromagnet Y1 of the two-position two-way bidirectional shut-off solenoid valve 215 connected to the left rear travel motor is signal-connected to the controller assembly 4.

[0115] The electromagnet Y2 of the two-position two-way bidirectional shut-off solenoid valve 215 connected to the right rear travel motor is signal-connected to the controller assembly 4.

[0116] The electromagnet Y3 of the two-position two-way bidirectional shut-off solenoid valve 215 connected to the left front travel motor is signal-connected to the controller assembly 4.

[0117] The electromagnet Y4 of the two-position two-way bidirectional shut-off solenoid valve 215 connected to the right front travel motor is connected to the controller assembly 4 via signal connection.

[0118] This invention can discharge all the oil from the high-pressure port of the self-rotating travel motor back to the hydraulic oil tank through the three-way shuttle valve 214 and the two-position two-way bidirectional shut-off solenoid valve 215 during the on-site bridge expansion process, thereby reducing the back pressure of the self-rotating travel motor, reducing the resistance of the bridge expansion cylinder, and reducing the energy consumption of the whole machine. At the same time, because the back pressure of the travel motor is small, when the tire adhesion is small, the travel motor can also self-rotate to prevent dragging and affecting the bridge expansion effect.

[0119] To further improve the working efficiency of the travel motors, all four travel motors are variable displacement motors. The control oil circuit of each travel motor is equipped with an electromagnetic directional valve 216, which has an electromagnet Y8 connected to the controller assembly 4 via signal. The oil pump 122 supplies control oil to the control oil circuit of the travel motors through the electromagnetic directional valve 216 to control the motor's displacement. The electromagnetic directional valve 216 connects the control oil circuit of the travel motors to the oil tank. When high torque and low speed are required, the controller assembly 4 controls the electromagnetic directional valve 216 via the electromagnet Y8 to control the motor's displacement; it can also switch between low torque and high speed.

[0120] In order to achieve separate braking control of the front and rear travel motors, each of the four travel motors is equipped with a hydraulic brake; the control oil circuit of the hydraulic brake of the two travel motors at the rear of the machine is equipped with a rear brake solenoid control valve 217, and the rear brake solenoid control valve 217 is equipped with an electromagnet Y7 that is signal-connected to the controller assembly 4.

[0121] The control oil circuit of the hydraulic brake of the two travel motors on the front side of the machine is equipped with a front brake solenoid control valve 218, and the front brake solenoid control valve 218 is equipped with an electromagnet Y6 that is signal-connected to the controller assembly 4.

[0122] The oil replenishment pump 122 provides control oil that is connected to the hydraulic brake of the travel motor through the rear brake solenoid control valve 217 and the front brake solenoid control valve 218. The controller assembly 4 controls the hydraulic brake of the rear travel motor and the hydraulic brake of the front travel motor respectively through electromagnets Y7 and Y6.

[0123] When it is necessary to control the front travel motor or the rear travel motor separately, the controller assembly 4 controls the rear brake solenoid control valve 217 or the front brake solenoid control valve 218 through electromagnet Y7 or electromagnet Y6 to release the brake of the corresponding front travel motor or the rear travel motor, thereby realizing the separate control of the front and rear travel motors.

[0124] To enable free rotation of the four wheels, the travel control valve 21 is equipped with a bidirectional shut-off solenoid valve 219 that connects to the inlet and outlet oil ports of the travel pump 12. The bidirectional shut-off solenoid valve 219 is equipped with an electromagnet Y5 that is signal-connected to the controller assembly 4. When the controller assembly 4 controls the electromagnet Y5 to be energized, the bidirectional shut-off solenoid valve 219 connects the oil passage between the inlet and outlet oil ports of the travel pump 12, and simultaneously connects the oil passages between the inlet and outlet oil ports of the four travel motors. High-pressure oil no longer enters the four travel motors, and the four travel motors can rotate freely.

[0125] like Figure 1-6 As shown, a control method for an on-site bridge expansion control system for an aerial work platform is disclosed. The on-site bridge expansion control method includes an off-ground bridge expansion mode.

[0126] The control method for the off-ground bridge expansion mode is as follows:

[0127] When the bridge is extended off the ground, neither electromagnets Y9 nor Y10 of the traveling pump 12 should be energized.

[0128] Step 1: Front axle expansion, controller assembly 4 controls the solenoid Y7 of the rear brake solenoid control valve 217 to be de-energized, and the two rear travel motors maintain braking.

[0129] The controller assembly 4 controls the steering expansion pump 13 to supply oil to the rodless chamber of the forward support cylinder 32 through the steering expansion control valve 31, and the front support assembly 52 extends out of the front end of the frame assembly 5 to lift the front support leg assembly off the ground.

[0130] Steering expansion pump 13 supplies oil to the rodless chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until it reaches the set value of the controller assembly 4, at which point steering expansion pump 13 stops supplying oil to the rodless chambers of the two front expansion cylinders.

[0131] The controller assembly 4 controls the steering expansion pump 13 to supply oil to the rod chamber of the forward support cylinder 32 through the steering expansion control valve 31. The front support assembly 52 retracts the front end of the frame assembly 5 and the front outrigger assembly touches the ground. The front support assembly 52 retracts to the initial state, completing the front axle expansion.

[0132] Step 2: After the rear axle is expanded, the electromagnet Y6 of the controller assembly 4 controlling the front brake solenoid control valve 218 is de-energized, and the two front travel motors remain braked.

[0133] The controller assembly 4 controls the steering expansion pump 13 to supply oil to the rodless chamber of the rear support cylinder 33 through the steering expansion control valve 31, and the rear support assembly 53 extends out of the rear of the frame assembly 5, raising the rear support leg assembly off the ground.

[0134] Steering expansion pump 13 supplies oil to the rodless chambers of the two rear expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until it reaches the set value of the controller assembly 4, at which point steering expansion pump 13 stops supplying oil to the rodless chambers of the two rear expansion cylinders.

[0135] The controller assembly 4 controls the steering expansion pump 13 to supply oil to the rod chamber of the rear support cylinder 33 through the steering expansion control valve 31. After the rear support assembly 53 retracts the rear of the frame assembly 5 and the outrigger assembly touches the ground, the rear support assembly 53 retracts to the initial state, completing the front axle expansion.

[0136] Step 3: Rear axle retraction. The rear support assembly 53 first supports the rear outrigger assembly, and the two rear axle expansion cylinders retract. After the rear outrigger assembly completes the axle retraction, the rear support assembly 53 retracts its tail and the outrigger assembly touches the ground. The rear support assembly 53 retracts to its initial state.

[0137] Step 4: Front axle retraction. The front support assembly 52 first supports the front outrigger assembly, and the two front axle expansion cylinders retract. After the front outrigger assembly completes the retraction, the front support assembly 52 retracts and the front outrigger assembly lands on the ground. The front support assembly 52 retracts to its initial state.

[0138] This invention uses the front support assembly 52 and the rear support assembly 53 to lift the front and rear parts of the frame body 51, respectively. When the front wheels of the frame body 51 are lifted off the ground, the steering axle widening control valve 31 controls the two front axle widening cylinders to complete the axle widening. Then, the front support assembly 52 retracts the front wheels to complete the axle widening and grounding. Similarly, the rear axle is widened and then grounded. Because the center of gravity of the aerial work platform is prone to shifting, the front support assembly 52 and the rear support assembly 53 cannot simultaneously lift all four wheels off the ground. Since the wheels are off the ground, they no longer contact the ground during the axle widening process, eliminating the need for driving force and reducing friction between the wheels and the ground. This reduces the resistance of the axle widening cylinders, achieving energy savings. With the wheels off the ground, the axle widening process is no longer limited by spatial conditions, making the axle widening process more stable and the widening angle more precise.

[0139] To improve the efficiency and diversify the methods for expanding bridges in place, control methods for expanding bridges in place include the level ground bridge expansion mode.

[0140] When the working ground is flat, the flat ground bridge expansion mode can be used. The control method for the flat ground bridge expansion mode is as follows:

[0141] During the bridge expansion and retraction process, the electromagnet Y5 of the bidirectional shut-off solenoid valve 219 is energized, while the electromagnet Y8 of the solenoid directional valve 216 is de-energized; the electromagnets Y9 and Y10 of the traveling pump 12 are not energized.

[0142] Step 1: Front axle expansion. The controller assembly 4 controls the front brake solenoid control valve 218 solenoid Y6 to be energized, while the rear brake solenoid control valve 217 solenoid Y7 is de-energized, releasing the brakes of the two front travel motors, while the two rear travel motors remain braked.

[0143] The steering expansion pump 13 injects oil into the rod chamber of the steering cylinder of the two front outrigger assemblies, and the steering cylinder begins to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly 4.

[0144] When the tire reaches the set angle of the controller assembly 4, the steering cylinder stops supplying oil, and the electromagnets Y3 and Y4 of the two-position two-way bidirectional shut-off solenoid valve 215 are energized. The two oil ports of the front travel motor are connected to the oil tank through the three-way shuttle valve 214 and the two-position two-way bidirectional shut-off solenoid valve 215, and the front travel motor can rotate freely.

[0145] Steering expansion pump 13 supplies oil to the rodless chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until it reaches the set value of controller assembly 4.

[0146] When the bridge expansion angle reaches the set value angle of the controller assembly 4, the steering bridge expansion pump 13 stops supplying oil to the rodless chambers of the two front bridge expansion cylinders, and the steering bridge expansion pump 13 supplies oil to the rodless chambers of the two front steering cylinders until the tire angle reaches the initial value. Then, the two-position two-way bidirectional shut-off solenoid valve 215 de-energizes electromagnets Y3 and Y4, and the front brake solenoid control valve 218 de-energizes electromagnet Y6, thus completing the front axle expansion.

[0147] Step 2: Rear axle expansion. The controller assembly 4 controls the rear brake solenoid control valve 217 solenoid Y7 to be energized, while the front brake solenoid control valve 218 solenoid Y6 is de-energized, releasing the brakes of the two rear travel motors, while the two front travel motors remain braked.

[0148] The steering expansion pump 13 feeds oil into the rod chambers of the two rear steering cylinders, and the aforementioned steering cylinders begin to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly 4.

[0149] When the tire reaches the set angle of the controller assembly 4, the steering cylinder stops supplying oil, and the electromagnets Y1 and Y2 of the two-position two-way bidirectional shut-off solenoid valve 215 are energized. The two oil ports of the rear travel motor are connected to the oil tank through the three-way shuttle valve 214 and the two-position two-way bidirectional shut-off solenoid valve 215, and the front travel motor can rotate freely.

[0150] Steering expansion pump 13 supplies oil to the rodless chambers of the two rear expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until it reaches the set value of controller assembly 4.

[0151] When the bridge expansion angle reaches the set value angle of the controller assembly 4, the steering bridge expansion pump 13 stops supplying oil to the rodless chamber of the rear bridge expansion cylinder, and the steering bridge expansion pump 13 feeds oil into the rodless chamber of the rear steering cylinder until the tire angle reaches the initial value. Electromagnets Y1, Y2, Y5 and Y7 are de-energized, and the bridge expansion is completed.

[0152] Step 3: Rear axle retraction, the method is the same as in Step 2. Steering expansion pump 13 supplies oil to the rod chamber of the two rear expansion cylinders. The above expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until the set value of the controller assembly 4 is reached.

[0153] The tire's steering angle returns to its initial value, electromagnets Y1, Y2, Y5, and Y7 are de-energized, and the rear axle retracts.

[0154] Step 4: Retract the front axle, using the same method as in Step 1.

[0155] Steering expansion pump 13 supplies oil to the rod chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until it reaches the set value of controller assembly 4.

[0156] The tire's steering angle returns to its initial value, and electromagnets Y3, Y4, Y5, and Y6 are de-energized, completing the front axle retraction.

[0157] In the flat ground bridge expansion mode, the bridge expansion is completed by simply pushing the outrigger assembly with the bridge expansion cylinder. During the flat ground bridge expansion process, the oil from the high-pressure port of the self-rotating travel motor is discharged back to the hydraulic oil tank through the three-way shuttle valve 214 and the two-position two-way bidirectional shut-off solenoid valve 215, thereby reducing the self-rotation back pressure of the travel motor, reducing the resistance of the bridge expansion cylinder, and reducing the energy consumption of the whole machine. At the same time, because the return oil back pressure of the travel motor is small, when the tire adhesion is small, the travel motor can also self-rotate to prevent dragging and affecting the bridge expansion effect.

[0158] To improve the efficiency and diversify the modes of on-site bridge widening, the control methods for on-site bridge widening include obstacle-crossing bridge widening modes.

[0159] When the working ground is uneven or sloping, the obstacle-crossing and bridge-expanding mode can be used. The control method for the obstacle-crossing and bridge-expanding mode is as follows:

[0160] When crossing obstacles and expanding the bridge, the electromagnet Y5 of the bidirectional shut-off solenoid valve 219 must not be energized during the expansion and retraction of the bridge; at the same time, electromagnets Y1, Y2, Y3 and Y4 must also not be energized.

[0161] Step 1: Front axle expansion. The controller assembly 4 controls the front brake solenoid control valve 218 solenoid Y6 to be energized, while the rear brake solenoid control valve 217 solenoid Y7 is de-energized, releasing the brakes of the two front travel motors, while the two rear travel motors remain braked.

[0162] When the steering expansion pump 13 pumps oil into the rod chamber of the steering cylinder, the steering cylinder begins to retract. The steering tire angle sensor monitors the tire angle in real time until the set value of the controller assembly 4 is reached.

[0163] When the tire reaches the set angle of the controller assembly 4, the steering cylinder stops supplying oil, the solenoid Y8 of the solenoid reversing valve 216 is energized, and at the same time the solenoid Y10 of the travel pump 12 is energized. The travel pump 12 supplies oil to the two travel motors on the front side, and the steering expansion pump 13 supplies oil to the rodless chamber of the front expansion cylinder. The aforementioned expansion cylinder begins to extend, and the expansion angle sensor monitors the angle of the front outrigger assembly in real time until it reaches the set value of the controller assembly 4.

[0164] When the bridge expansion angle reaches the set angle of the controller assembly 4, the electromagnet Y8 of the solenoid reversing valve 216 is de-energized, and at the same time the electromagnet Y10 of the travel pump 12 is de-energized, and the travel pump 12 stops supplying oil to the travel motor; the steering bridge expansion pump 13 stops supplying oil to the rodless chamber of the forward bridge expansion cylinder, and the steering bridge expansion pump 13 supplies oil to the rodless chamber of the forward steering cylinder until the tire angle reaches the initial value. Finally, the electromagnet Y6 of the front brake solenoid control valve 218 is de-energized, and the front axle expansion is completed.

[0165] Step 2: Expand the rear axle, release the brake on the rear travel motor, and keep the brake on the front travel motor; rotate the two rear tires to the set value of controller assembly 4.

[0166] When the solenoid Y8 of the solenoid directional valve 216 is energized, the solenoid Y9 of the travel pump 12 is also energized. The travel pump 12 supplies oil to the rear travel motor, and the steering expansion pump 13 supplies oil to the rodless chamber of the rear expansion cylinder. The aforementioned expansion cylinder begins to extend. The expansion angle sensor monitors the angle of the rear outrigger assembly in real time until it reaches the set value of the controller assembly 4. The travel pump 12 stops supplying oil to the rear travel motor. The steering expansion pump 13 stops supplying oil to the rodless chamber of the rear expansion cylinder. The tire angle returns to its initial value. Finally, the solenoid Y7 of the rear brake solenoid control valve 217 is de-energized, and the rear axle expansion is completed.

[0167] Step 3: Rear axle retraction. The method is the same as in Step 2. Steering expansion pump 13 supplies oil to the rod chamber of the rear expansion cylinder, and the rear expansion cylinder begins to retract, thus completing the rear axle retraction.

[0168] Step 4: Front axle retraction. The method is the same as in Step 1. Steering expansion pump 13 supplies oil to the rod chamber of the front expansion cylinder, and the front expansion cylinder begins to retract, completing the front axle retraction.

[0169] The obstacle-crossing and bridge-widening mode combines the thrust of the bridge-widening cylinder and the driving force of the travel motor to complete the bridge widening, thus improving the ability to widen the bridge on the spot.

[0170] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0171] The above description of the disclosed embodiments enables those skilled in the art to make or use the 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 invention. Therefore, the invention is not 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 control system for extending the bridge on the spot of an aerial work platform, comprising a powertrain (1), a travel hydraulic system (2), a steering and bridge-extending hydraulic system (3), a controller assembly (4), and a frame assembly (5), wherein the powertrain (1) provides high-pressure hydraulic fluid to the travel hydraulic system (2) and the steering and bridge-extending hydraulic system (3), the controller assembly (4) is connected to the travel hydraulic system (2) and the steering and bridge-extending hydraulic system (3) via signals, and the travel hydraulic system (2) and the steering and bridge-extending hydraulic system (3) are mounted on the frame assembly (5) and drive the actuators of the frame assembly (5); characterized in that: The powertrain (1) includes a power unit (11), a travel pump (12) and a steering expansion pump (13), and the power output end of the power unit (11) is simultaneously connected to the travel pump (12) and the steering expansion pump (13). The walking hydraulic system (2) includes a walking control valve (21) and four walking motors. The walking pump (12) drives the four walking motors respectively through the walking control valve (21). The steering bridge expansion hydraulic system (3) includes a steering bridge expansion control valve (31), a front support cylinder (32), a rear support cylinder (33), four steering cylinders and four expansion cylinders; the steering bridge expansion pump (13) controls the front support cylinder (32), the rear support cylinder (33), the four steering cylinders and the four expansion cylinders respectively through the steering bridge expansion control valve (31); The controller assembly (4) is connected to the travel control valve (21) and the steering bridge control valve (31) respectively; The frame assembly (5) includes a frame body (51), a front support assembly (52), a rear support assembly (53), and four support leg assemblies hinged to the frame body (51). The upper ends of the front support assembly (52) and the rear support assembly (53) are respectively fixedly installed on the front and rear sides of the frame body (51). The front support assembly (52) and the rear support assembly (53) are telescopic structures with a front support cylinder (32) and a rear support cylinder (33) inside. The front support cylinder (32) extends out to lift the front of the frame body (51), and the two front wheels are off the ground. The rear support cylinder (33) extends out to lift the rear of the frame body (51), and the two rear wheels are off the ground.

2. The aerial work platform in-situ bridge widening control system according to claim 1, characterized in that: The travel pump (12) includes a travel pump solenoid control valve (121) and a replenishing pump (122). The solenoid control valve (121) of the walking pump is a three-position four-way solenoid valve. Electromagnets Y9 and Y10, which are connected to the controller assembly (4), are respectively provided on both sides of the solenoid control valve (121). When neither electromagnet Y9 nor electromagnet Y10 is energized, the solenoid control valve (121) of the walking pump is in the middle position and the flow of the walking pump (12) is zero. When one of the electromagnets Y9 and Y10 is energized, the walking pump (12) starts to supply oil, and when either electromagnet Y9 or electromagnet Y10 is energized, the direction of oil supply of the walking pump (12) is opposite. The replenishing pump (122) is driven by the power unit (11) and operates synchronously with the walking pump (12). The oil inlet of the replenishing pump (122) is connected to the oil tank, and the oil outlet of the replenishing pump (122) is connected to the walking hydraulic system (2).

3. The aerial work platform in-situ bridge widening control system according to claim 2, characterized in that: The walking pump (12) drives four walking motors respectively through the walking control valve (21); The travel control valve (21) includes a first diversion and combination valve (211), a second diversion and combination valve (212), and a third diversion and combination valve (213). The two front travel motors and the two rear travel motors merge and are respectively connected to the diversion port of the first diversion and combination valve (211). The combination port of the first diversion and combination valve (211) is connected to the A oil port of the travel pump (12). The other oil ports of the two rear travel motors on the left and right are connected to the diversion ports of the second diversion and merging valve (212), and the merging port of the second diversion and merging valve (212) is connected to the B oil port of the travel pump (12). The other oil ports of the two left and right front travel motors are connected to the diversion ports of the third diversion and merging valve (213), and the merging port of the third diversion and merging valve (213) is connected to the B oil port of the travel pump (12).

4. The aerial work platform in-situ bridge widening control system according to claim 2 or 3, characterized in that: The four walking motors are respectively equipped with three-way shuttle valves (214) connected in parallel at both ends. The two oil inlets of the three-way shuttle valves (214) are respectively connected to the oil inlet and outlet of the walking motors, and the oil outlet of the three-way shuttle valves (214) is connected to the oil tank. The three-way shuttle valve (214) is equipped with a two-position two-way bidirectional shut-off solenoid valve (215) on the oil line between the oil outlet of the three-way shuttle valve (214) and the oil tank. The electromagnet Y1 of the two-position two-way bidirectional shut-off solenoid valve (215) connected to the left rear walking motor is signal-connected to the controller assembly (4); The electromagnet Y2 of the two-position two-way bidirectional shut-off solenoid valve (215) connected to the right rear walking motor is connected to the controller assembly (4) via signal. The electromagnet Y3 of the two-position two-way bidirectional shut-off solenoid valve (215) connected to the left front travel motor is connected to the controller assembly (4) via signal. The electromagnet Y4 of the two-position two-way bidirectional shut-off solenoid valve (215) connected to the right front travel motor is signal-connected to the controller assembly (4).

5. The aerial work platform in-situ bridge widening control system according to claim 4, characterized in that: All four travel motors are variable displacement motors. The control oil circuit of the travel motor is equipped with an electromagnetic reversing valve (216). The electromagnetic reversing valve (216) is equipped with an electromagnet Y8 that is signal-connected to the controller assembly (4). The oil replenishment pump (122) provides control oil to the control oil circuit of the travel motor through the electromagnetic reversing valve (216) to control the displacement of the travel motor. The control oil circuit of the travel motor and the oil tank are connected through the electromagnetic reversing valve (216).

6. The aerial work platform in-situ bridge widening control system according to claim 5, characterized in that: Each of the four walking motors is equipped with a hydraulic brake; The control oil circuit of the hydraulic brake of the two walking motors on the rear side of the whole machine is equipped with a rear brake solenoid control valve (217), and the rear brake solenoid control valve (217) is equipped with an electromagnet Y7 that is connected to the controller assembly (4) by signal. The control oil circuit of the hydraulic brake of the two walking motors on the front side of the machine is equipped with a front brake solenoid control valve (218), and the front brake solenoid control valve (218) is equipped with an electromagnet Y6 that is connected to the controller assembly (4) by signal. The oil replenishment pump (122) provides control oil to be connected to the control oil circuit of the hydraulic brake of the travel motor through the rear brake solenoid control valve (217) and the front brake solenoid control valve (218). The controller assembly (4) controls the hydraulic brake of the rear travel motor and the hydraulic brake of the front travel motor respectively through electromagnets Y7 and Y6.

7. The aerial work platform in-situ bridge widening control system according to claim 2 or 6, characterized in that: The walking control valve (21) is equipped with a two-way shut-off solenoid valve (219) that connects to the inlet and outlet of the walking pump (12); the two-way shut-off solenoid valve (219) is equipped with an electromagnet Y5 that is signal-connected to the controller assembly (4).

8. A control method for an on-site bridge widening control system for an aerial work platform, characterized in that: Control methods for on-site bridge widening include off-ground bridge widening mode. The control method for the off-ground bridge expansion mode is as follows: When the bridge is extended off the ground, the electromagnets Y9 and Y10 of the traveling pump (12) should not be energized. Step 1: Front axle expansion, controller assembly (4) controls the electromagnet Y7 of the rear brake solenoid control valve (217) to be de-energized, and the two rear travel motors maintain braking; The controller assembly (4) controls the steering expansion pump (13) to supply oil to the rodless chamber of the forward support cylinder (32) through the steering expansion control valve (31), and the front support assembly (52) extends out of the frame assembly (5) and lifts the front outrigger assembly off the ground; Steering expansion pump (13) supplies oil to the rodless chambers of the two front expansion cylinders. The expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until it reaches the set value of the controller assembly (4). Then, steering expansion pump (13) stops supplying oil to the rodless chambers of the two front expansion cylinders. The controller assembly (4) controls the steering expansion pump (13) to supply oil to the rod chamber of the forward support cylinder (32) through the steering expansion control valve (31). The front support assembly (52) retracts the frame assembly (5), the front end of the front support leg assembly falls back to the ground, and the front support assembly (52) retracts to the initial state, completing the front axle expansion. Step 2: Rear axle expansion, controller assembly (4) controls the electromagnet Y6 of the front brake solenoid control valve (218) to be de-energized, and the two front travel motors maintain braking; The controller assembly (4) controls the steering expansion pump (13) to supply oil to the rodless chamber of the rear support cylinder (33) through the steering expansion control valve (31), and the rear support assembly (53) extends out of the frame assembly (5) and the rear support leg assembly lifts off the ground; The steering expansion pump (13) supplies oil to the rodless chamber of the two rear expansion cylinders. The aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear support leg assemblies in real time until it reaches the set value of the controller assembly (4). The steering expansion pump (13) then stops supplying oil to the rodless chamber of the two rear expansion cylinders. The controller assembly (4) controls the steering expansion pump (13) to supply oil to the rod chamber of the rear support cylinder (33) through the steering expansion control valve (31). The rear support assembly (53) retracts the frame assembly (5). After the rear end falls back, the outrigger assembly touches the ground. The rear support assembly (53) retracts to the initial state, completing the front axle expansion. Step 3: Rear axle retraction. The rear support assembly (53) first supports the rear outrigger assembly, and the two rear axle expansion cylinders retract. After the rear outrigger assembly completes the retraction, the rear support assembly (53) retracts its tail and the outrigger assembly touches the ground. The rear support assembly (53) retracts to its initial state. Step 4: Front axle retraction. The front support assembly (52) first supports the front outrigger assembly. The two front axle expansion cylinders retract. After the front outrigger assembly completes the retraction, the front support assembly (52) retracts and the front end falls back to the ground. The front support assembly (52) retracts to the initial state.

9. The control method of the aerial work platform in-situ bridge widening control system according to claim 8, characterized in that: Control methods for expanding bridges in situ include the bridge expansion mode on flat ground. The control method for the flat-ground bridge expansion mode is as follows: During the bridge expansion and retraction process, the electromagnet Y5 of the bidirectional shut-off solenoid valve (219) is energized, while the electromagnet Y8 of the solenoid directional valve (216) is de-energized; the electromagnets Y9 and Y10 of the traveling pump (12) are not energized. Step 1: Front axle expansion, controller assembly (4) controls the electromagnet Y6 of the front brake solenoid control valve (218) to be energized, while the electromagnet Y7 of the rear brake solenoid control valve (217) is de-energized, releasing the brakes of the two front travel motors, while the two rear travel motors remain braked. The steering expansion pump (13) feeds oil into the rod chamber of the steering cylinder of the two front outrigger assemblies. The steering cylinder begins to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly (4). When the tire reaches the set angle of the controller assembly (4), the steering cylinder stops supplying oil, and the electromagnets Y3 and Y4 of the two-position two-way bidirectional shut-off solenoid valve (215) are energized. The two oil ports of the front travel motor are connected to the oil tank through the three-way shuttle valve (214) and the two-position two-way bidirectional shut-off solenoid valve (215), and the front travel motor can rotate freely. The steering expansion pump (13) supplies oil to the rodless chambers of the two front expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until the set value of the controller assembly (4) is reached. When the bridge expansion angle reaches the set value angle of the controller assembly (4), the steering bridge expansion pump (13) stops supplying oil to the rodless chambers of the two front bridge expansion cylinders, and the steering bridge expansion pump (13) supplies oil to the rodless chambers of the two front steering cylinders until the tire angle reaches the initial value. The two-position two-way bidirectional shut-off solenoid valve (215) electromagnets Y3 and Y4 are de-energized, and the front brake solenoid control valve (218) electromagnet Y6 is de-energized, thus completing the front axle expansion. Step 2: Rear axle expansion, controller assembly (4) controls the rear brake solenoid control valve (217) solenoid Y7 to be energized, while the front brake solenoid control valve (218) solenoid Y6 is not energized, releasing the brakes of the two rear travel motors, while the two front travel motors remain braked. The steering expansion pump (13) feeds oil into the rod chambers of the two rear steering cylinders, and the steering cylinders begin to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly (4). When the tire reaches the set angle of the controller assembly (4), the steering cylinder stops supplying oil, and the electromagnets Y1 and Y2 of the two-position two-way bidirectional shut-off solenoid valve (215) are energized. The two oil ports of the rear travel motor are connected to the oil tank through the three-way shuttle valve (214) and the two-position two-way bidirectional shut-off solenoid valve (215), and the front travel motor can rotate freely. The steering expansion pump (13) supplies oil to the rodless chamber of the two rear expansion cylinders, and the aforementioned expansion cylinders begin to extend. The expansion angle sensor monitors the angle of the two rear support leg assemblies in real time until the set value of the controller assembly (4) is reached. When the bridge expansion angle reaches the set value angle of the controller assembly (4), the steering bridge expansion pump (13) stops supplying oil to the rodless chamber of the rear bridge expansion cylinder, and the steering bridge expansion pump (13) feeds oil into the rodless chamber of the rear steering cylinder until the tire angle reaches the initial value. Electromagnets Y1, Y2, Y5 and Y7 are de-energized, and the bridge expansion is completed. Step 3: Rear axle retraction, the method is the same as in step 2. Steering expansion pump (13) supplies oil to the rod chamber of the two rear expansion cylinders. The above expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two rear outrigger assemblies in real time until the set value of the controller assembly (4) is reached. The tire's steering angle returns to its initial value, electromagnets Y1, Y2, Y5, and Y7 are de-energized, and the rear axle retracts. Step 4: Retract the front axle, using the same method as in Step 1. The steering expansion pump (13) supplies oil to the rod chambers of the two front expansion cylinders. The expansion cylinders begin to retract. The expansion angle sensor monitors the angle of the two front outrigger assemblies in real time until the set value of the controller assembly (4) is reached. The tire's steering angle returns to its initial value, and electromagnets Y3, Y4, Y5, and Y6 are de-energized, completing the front axle retraction.

10. The control method of the aerial work platform in-situ bridge widening control system according to claim 8 or 9, characterized in that: Control methods for expanding bridges in place include obstacle-crossing bridge expansion mode. The control method for the obstacle-crossing and bridge-expanding mode is as follows: When crossing obstacles and expanding the bridge, the electromagnet Y5 of the bidirectional shut-off solenoid valve (219) must not be energized during the expansion and retraction of the bridge; at the same time, electromagnets Y1, Y2, Y3 and Y4 must not be energized. Step 1: Front axle expansion, controller assembly (4) controls the electromagnet Y6 of the front brake solenoid control valve (218) to be energized, while the electromagnet Y7 of the rear brake solenoid control valve (217) is de-energized, releasing the brakes of the two front travel motors, while the two rear travel motors remain braked. The steering expansion pump (13) feeds oil into the rod chamber of the forward steering cylinder, and the steering cylinder begins to retract. The steering tire angle sensor monitors the tire angle in real time until it reaches the set value of the controller assembly (4). When the tire reaches the set angle of the controller assembly (4), the steering cylinder stops supplying oil, the electromagnet Y8 of the solenoid reversing valve (216) is energized, and at the same time the electromagnet Y10 of the travel pump (12) is energized. The travel pump (12) supplies oil to the two travel motors on the front side, and the steering expansion pump (13) supplies oil to the rodless chamber of the front expansion cylinder. The above-mentioned expansion cylinder begins to extend, and the expansion angle sensor monitors the angle of the front outrigger assembly in real time until it reaches the set value of the controller assembly (4). When the bridge expansion angle reaches the set value angle of the controller assembly (4), the electromagnet Y8 of the electromagnetic reversing valve (216) is de-energized, and at the same time the electromagnet Y10 of the travel pump (12) is de-energized, and the travel pump (12) stops supplying oil to the travel motor; the steering bridge expansion pump (13) stops supplying oil to the rodless chamber of the forward bridge expansion cylinder, and the steering bridge expansion pump (13) supplies oil to the rodless chamber of the forward steering cylinder until the tire angle reaches the initial value. Finally, the electromagnet Y6 of the front brake electromagnetic control valve (218) is de-energized, and the front axle expansion is completed. Step 2: Expand the rear axle, release the brake on the rear travel motor, and keep the front travel motor brake on; rotate the two rear tires to the set value of the controller assembly (4). When the electromagnet Y8 of the electromagnetic reversing valve (216) is energized, the electromagnet Y9 of the travel pump (12) is energized, the travel pump (12) supplies oil to the rear travel motor, and the steering expansion pump (13) supplies oil to the rodless chamber of the rear expansion cylinder. The aforementioned expansion cylinder begins to extend, and the expansion angle sensor monitors the angle of the rear outrigger assembly in real time until it reaches the set value of the controller assembly (4). The travel pump (12) stops supplying oil to the rear travel motor. The steering expansion pump (13) stops supplying oil to the rodless chamber of the rear expansion cylinder. The tire angle returns to the initial value. Finally, the electromagnet Y7 of the rear brake electromagnetic control valve (217) is de-energized, and the rear axle expansion is completed. Step 3: Retract the rear axle. The method is the same as in Step 2. The steering expansion pump (13) supplies oil to the rod chamber of the rear expansion cylinder. The rear expansion cylinder begins to retract, and the rear axle is retracted. Step 4: Front axle retraction. The method is the same as in Step 1. Steering expansion pump (13) supplies oil to the rod chamber of front expansion cylinder, and front expansion cylinder begins to retract, completing the front axle retraction.

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