CN110566522A - Active floating control system for underframe and aerial work platform thereof - Google Patents

Abstract

The invention discloses an active floating control system of an underframe and an aerial work platform thereof. The active floating control system of an underframe comprises: a controller, a hydraulic power mechanism, a floating control mechanism, an aerial work control mechanism and an active floating switching device; The high-altitude work platform includes the active floating control system of the underframe, and also includes a car body, a turntable, a jib and a working platform. The control system and the high-altitude work platform are equipped with an active floating switching device, so that the high-altitude work platform can control the start and stop of the active floating working mode to cope with different working conditions. The aerial work platform starts the active floating working mode when walking to ensure the stability of walking and prevent tipping; stops the active floating working mode when stopping walking to ensure that the bottom frame will not float up and down when getting on the vehicle, making the operation more stable comfortable.

Description

An underframe active floating control system and its aerial work platform

technical field

The invention relates to the field of engineering machinery, in particular to an active floating control system of an underframe and an aerial work platform thereof.

Background technique

In order to improve the walking stability of the whole vehicle and the passing capacity under different road conditions in the existing aerial work platforms, the walking undercarriage adopts a structural mode in which the front axle 170 floats and the rear axle 180 swings. The specific structure is shown in Fig. 2: the left and right sides of the front axle 170 each have a floating oil cylinder, and under the joint action of the floating oil cylinders, the front axle 170 can swing up and down around the swing axis. Similarly, the rear axle 180 also adopts a swing structure. During walking, the rear axle 180 swings with the ground while controlling the expansion and contraction of the floating oil cylinder of the front axle 170 through the floating control valve 132 structurally associated with it, so as to realize the complete vehicle. Active floating function during walking.

During the running of the whole vehicle, there will inevitably be unexpected situations, such as the tire on the side of the front axle 170 suddenly falling into a pit. It will affect the stability of the whole vehicle, and even cause the risk of overturning, endangering the personal safety of the operator. Therefore, this working condition has higher requirements for the quick response of the floating cylinder. In order to solve the above problems, the existing hydraulic control system adopts active control. In FIG. One oil inlet P is connected to the third oil inlet P1 of the solenoid valve 161, the first oil inlet P1 of the flow stabilization device 131 is connected to the fourth oil inlet P of the floating control valve 132, and the A port of the floating control valve 132 At the same time, it is connected with the V1 port of the balance valve of the left floating oil cylinder 133 and the V2 port of the right floating oil cylinder 134 balance valve, and the B port of the floating control valve 132 is connected with the V2 port of the balance valve of the left floating oil cylinder 133 and the V1 of the balance valve of the right floating oil cylinder 134 The first oil return port T of the floating control valve 132 is connected to the second oil return port T of the main control valve group 141 and the third oil return port T1 of the solenoid valve 161 to return to the hydraulic oil tank 122 . The A1 port of the main control valve group 141 is connected with the rodless chamber of the main boom telescopic cylinder 142, the B1 port is connected with the rod chamber of the main boom telescopic cylinder 142, the A2 port is connected with the rodless chamber of the main boom luffing cylinder 143, and the B2 The port is connected with the rod cavity of the main arm luffing cylinder 143, the A3 port is connected with the A port of the turntable rotary motor 144, and the B3 port is connected with the B port of the turntable rotary motor 144. The electric control travel handle 101 is connected with the swash plate control proportional valve of the closed travel pump 102 through the controller 110, the A port of the closed travel pump 102 is connected with the A port of the travel motor 103, and the B port of the closed travel pump 102 Link to port B of travel motor 103.

Specifically, the operator first energizes the solenoid valve 161 through an enabling switch (such as a foot switch, etc.), and after the spool of the solenoid valve 161 changes direction, its third oil inlet P1 is connected with the first working oil port A, so that The first oil outlet P of the variable pump 121 is directly connected with the first load feedback oil port LS of the variable pump 121, and then the outlet pressure of the variable pump 121 begins to rise. When it rises to the set value of the pressure control valve of the variable pump 121, The spool of the pressure control valve is reversed, and the variable displacement pump 121 enters constant pressure control (that is, the pump outlet maintains a high-pressure standby state). Then operate the manual action to walk, and the electric control walking handle 101 controls the closed walking pump 102 swash plate variable output pressure oil to drive the walking motor 103 to rotate. When the underframe rear axle 180 swings and pulls the spool of the floating control valve 132 to change direction, the pressure oil at the outlet of the variable pump 121 passes through the steady flow device 131 to the fourth oil inlet P of the floating control valve 132, and when the floating control valve 132 valve The core moves to the right (that is, the left position is connected to the oil circuit), the fourth oil inlet P of the floating control valve 132 communicates with the third oil outlet A, and the high-pressure oil enters the V1 port and the right The V2 port of the balance valve of the floating oil cylinder 134 drives the piston rod of the left floating oil cylinder 133 to extend and the piston rod of the right floating oil cylinder 134 to retract, and then pushes the front axle 170 to swing around the swing axis. At this time, the left floating oil cylinder 133 balance valve The return oil from the V2 port and the V1 port of the balance valve of the right floating oil cylinder 134 flows back to the hydraulic oil tank 122 through the fourth oil outlet B and the first oil return port T of the floating control valve 132 . Similarly, when the spool of the floating control valve 132 moves to the left (that is, the right position is connected to the oil circuit), the fourth oil inlet P of the floating control valve 132 communicates with the fourth oil outlet B, and the high-pressure oil enters the right floating The V1 port of the balance valve of the oil cylinder 134 and the V2 port of the balance valve of the left floating oil cylinder 133 drive the piston rod of the right floating oil cylinder 134 to extend and the piston rod of the left floating oil cylinder 133 to retract, and then push the front axle 170 to swing around the swing axis. At this time, the return oil from the V2 port of the balance valve of the right floating cylinder 134 and the V1 port of the balance valve of the left floating cylinder 133 flows back to the hydraulic oil tank 122 through the fourth oil outlet B and the first oil return port T of the floating control valve 132 .

When walking is stopped, the pump outlet of the variable pump 121 maintains a high-pressure standby state. When the operation related to boarding is performed, for example: when the main arm is extended, the DT1 of the electric proportional reversing valve in the main control valve group 141 is energized (left position connected to the oil circuit), the variable pump 121 supplies oil to the boom, and the variable pump 121 supplies oil to the flow stabilization device 131 and the floating control valve 132 at the same time, and then supplies oil to the floating oil cylinder to realize active floating control.

Existing problems are: the variable pump 121 that controls active floating is always on standby during the entire operation process (driving, boarding operations, etc.), and the hydraulic oil entering the floating oil cylinder is completely controlled by the floating control valve 132 . When the aerial work platform is adjusted in place, the spool of the floating control valve 132 is in the middle position, sealing the hydraulic oil entering the floating oil cylinder, and the whole vehicle remains in a stable state. , due to the change of the center of gravity of the aerial work platform, the frame sometimes undergoes a large deformation. Since the spool of the floating control valve 132 is connected to the frame through a mechanical linkage, when the deformation of the frame is large, the spool in the mechanical linkage The pull of the hydraulic valve deviates from the neutral position of the hydraulic valve. At this time, the active floating oil source provided by the variable pump 121 will supply oil to the floating oil cylinder to perform active floating action. During the adjustment process of the floating oil cylinder, the frame will rise or fall together. If boarding operations are performed, such as turning movements, the two actions will superimpose each other, which will easily cause the vibration of the boarding action to intensify, and the operation comfort is extremely poor, which will affect customer satisfaction.

Contents of the invention

In order to solve the above-mentioned technical problems, the object of the present invention is to provide an active floating control system of the undercarriage that does not affect the movement of getting on the vehicle when walking is stopped, and to provide an aerial work platform including the above-mentioned system with good operating comfort.

The technical solution adopted in the present invention is: an active floating control system of the underframe, including: a controller, a hydraulic power mechanism, a floating control mechanism, a high-altitude operation control mechanism and an active floating switching device;

The controller is electrically connected to the hydraulic power mechanism, the floating control mechanism and the high-altitude operation control mechanism, and is used to output control signals to the hydraulic power mechanism, the floating control mechanism and the high-altitude operation control mechanism; The road connects the floating control mechanism and the high-altitude operation control mechanism for driving the floating control mechanism and the high-altitude operation control mechanism; the active floating switching device is arranged between the hydraulic power mechanism and the floating control mechanism for controlling On-off of the pipeline between the hydraulic power mechanism and the floating control mechanism.

Further, the active floating switching device is a solenoid valve, a hydraulic valve or a mechanical valve, which is used to control the on-off of the connected pipeline.

Further, the hydraulic power mechanism includes a variable pump and a hydraulic oil tank; the variable pump is connected to the hydraulic oil tank, and the variable pump is provided with a first oil outlet P and a first oil outlet P provided on the high-altitude operation control mechanism. The two oil inlets P are connected, and the first oil outlet P is connected with the first oil inlet P provided on the floating control mechanism through the active floating switching device; the first oil outlet P provided on the floating control mechanism The oil port T and the second oil return port T provided on the high-altitude operation control mechanism are respectively connected with the hydraulic oil tank.

Further, the control system also includes a sensitive switching device; the sensitive switching device includes a solenoid valve and a three-way shuttle valve, the solenoid valve is a two-position three-way solenoid valve and has a third oil inlet P, a third oil return port T and the first working oil port A, the three-way shuttle valve has the second working oil port A, the third load feedback oil port LS and the fourth load feedback oil port LS, wherein the third load feedback oil port LS is one-way The input port, the fourth load feedback oil port LS is the output port;

The third oil inlet P is connected to the first oil outlet P of the variable pump, the third oil return port T is connected to the hydraulic oil tank, and the first working oil port A is connected to the second working port of the three-way shuttle valve. Oil port A, the fourth load feedback oil port LS is connected to the first load feedback oil port LS of the variable displacement pump, and the third load feedback oil port LS is connected to the second load feedback oil port of the aerial work control mechanism LS.

Further, the sensitive switching device is also provided with a first throttling device and a second throttling device, the first throttling device is located between the third oil inlet P and the first oil outlet P, the second throttling device The throttling device is located between the third oil return port T and the hydraulic oil tank.

Further, the floating control mechanism includes a flow stabilizing device, a floating control valve, a left floating oil cylinder and a right floating oil cylinder; the first oil inlet P of the floating control mechanism is arranged on the flow stabilizing device; the floating control mechanism The first oil return port T of the floating control valve is set on the floating control valve; the flow stabilization device is also provided with a second oil outlet P connected to the fourth oil inlet P provided on the floating control valve; the The floating control valve is also provided with a third oil outlet A and a fourth oil outlet B, and the third oil outlet A is connected with the V port of the balance valve of the left floating oil cylinder and the V port of the balance valve of the right floating oil cylinder at the same time, so The fourth oil outlet B is connected with the V port of the balance valve of the left floating oil cylinder and the V port of the balance valve of the right floating oil cylinder at the same time.

Further, the flow stabilizing device is a speed regulating valve.

Further, the high-altitude operation control mechanism includes a main control valve group, a main arm telescopic oil cylinder, a main arm luffing oil cylinder and a turntable rotary motor; the second oil inlet P, the second load feedback oil port LS and the second oil return port The ports T are all set on the main control valve group; the main control valve group also has a proportional reversing valve for the main boom telescopic cylinder, a proportional reversing valve for the main boom luffing cylinder, a proportional reversing valve for the turntable rotation, and a relief valve. and a third throttling device;

The oil inlet end of the main boom telescopic oil cylinder proportional directional valve, the main arm luffing oil cylinder proportional directional valve and the turntable rotary proportional directional valve are connected in parallel with the second oil inlet P, and the oil return end is connected in parallel with the second oil return port T; The proportional reversing valve of the main boom telescopic oil cylinder is provided with a working oil port A1 and a working oil port B1 to respectively connect the rodless chamber and the rod chamber of the main boom telescopic oil cylinder; the proportional reversing valve of the main boom luffing cylinder is set There are working oil port A2 and working oil port B2 to respectively connect the rodless chamber and the rod chamber of the main arm luffing cylinder; the turntable rotation proportional reversing valve is provided with working oil port A3 and working oil port B3 Turntable rotary motor;

The second oil inlet P is connected to the second oil return port T through a relief valve; the working oil port A1, working oil port B1, working oil port A2, working oil port B2, working oil port A3 and working oil port Each of B3 is connected in parallel to the second load feedback oil port LS through a one-way valve, and the second load feedback oil port LS is connected to the second oil return port T through a third throttling device.

Further, it also includes an electronically controlled travel handle, a closed travel pump and a travel motor; the closed travel pump is provided with a third working oil port A, a fourth working oil port B and a swash plate control proportional valve for controlling output; The travel motor is provided with a fifth working oil port A and a sixth working oil port B; the controller is electrically connected to the electric control travel handle and the swash plate control proportional valve of the closed travel pump; the third working oil Port A is connected to the fifth working oil port A, and the fourth working oil port B is connected to the sixth working oil port B.

The application also provides an aerial work platform, including a vehicle body, a turntable, a jib, a working platform and the underframe active floating control system; the vehicle body has a front axle, a rear axle, and a The wheels on the bridge; the turntable is installed on the car body; the arm frame is installed on the turntable; the working platform is installed on the arm frame.

Beneficial effects of specific embodiments of the present invention: the control system and the aerial work platform are equipped with an active floating switching device, so that the aerial work platform can control the start and stop of the active floating working mode to cope with different working conditions. The aerial work platform starts the active floating working mode when walking to ensure the stability of walking and prevent tipping; stops the active floating working mode when stopping walking to ensure that the bottom frame will not float up and down when getting on the vehicle, making the operation more stable comfortable.

Description of drawings

The present invention will be described in detail below with reference to the drawings and specific embodiments.

Fig. 1 is a schematic side view of an aerial work platform in an embodiment of the present invention;

Fig. 2 is a schematic front view of the aerial work platform in the embodiment of the present invention;

Fig. 3 is a structural diagram of a traditional hydraulic control system;

Fig. 4 is a structural diagram of the active floating control system of the chassis in the embodiment of the present invention;

Fig. 5 is a structural diagram of a sensitive switching device in an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Referring to FIG. 1 , FIG. 2 , FIG. 4 and FIG. 5 , an embodiment of the present invention provides an active floating control system for an underframe and an aerial work platform thereof.

As shown in FIG. 4 , an active floating control system for an underframe includes: a controller 110 , a hydraulic power mechanism 120 , a floating control mechanism 130 , a high-altitude operation control mechanism 140 and an active floating switching device 150 ;

The controller 110 is electrically connected to the hydraulic power mechanism 120, the floating control mechanism 130 and the high-altitude operation control mechanism 140, and is used to output control signals to the hydraulic power mechanism 120, the floating control mechanism 130 and the high-altitude operation control mechanism 140; The road connects the floating control mechanism 130 and the high-altitude operation control mechanism 140 for driving the floating control mechanism 130 and the high-altitude operation control mechanism 140; the active floating switching device 150 is arranged between the hydraulic power mechanism 120 and the floating control mechanism 130 for controlling the hydraulic pressure The on-off of the pipeline between the power mechanism 120 and the floating control mechanism 130.

In the example of the present invention, the active floating switching device 150 is a solenoid valve, a hydraulic valve or a mechanical valve, which is used to control the on-off of the connected pipeline.

In the example of the present invention, the hydraulic power mechanism 120 includes a variable pump 121 and a hydraulic oil tank 122; The two oil inlets P are connected, and the first oil outlet P is connected with the first oil inlet P provided on the floating control mechanism 130 through the active floating switching device 150; the first oil return port T provided on the floating control mechanism 130 It is connected with the hydraulic oil tank 122 respectively with the second oil return port T provided on the high-altitude operation control mechanism 140 .

As shown in Figure 5, the example of the present invention also includes a sensitive switching device 160; the sensitive switching device 160 includes a solenoid valve 161 and a three-way shuttle valve 162, and the solenoid valve 161 is a two-position three-way solenoid valve and has a third oil inlet P1, The third oil return port T1 and the first working oil port A, the three-way shuttle valve 162 has the second working oil port A, the third load feedback oil port LS1 and the fourth load feedback oil port LS2, wherein the third load feedback oil port LS1 is a one-way input port, the fourth load feedback oil port LS2 is an output port, the third oil inlet P1 is connected to the first oil outlet P of the variable pump 121, the third oil return port T1 is connected to the hydraulic oil tank 122, and the first working Oil port A is connected to the second working oil port A of the three-way shuttle valve 162, the fourth load feedback oil port LS2 is connected to the first load feedback oil port LS of the variable pump 121, and the third load feedback oil port LS1 is connected to the high-altitude operation control mechanism 140 The second load feedback oil port LS.

Preferably, the sensitive switching device 160 is also provided with a first throttling device 163 and a second throttling device 164, the first throttling device 163 is located between the third oil inlet P1 and the first oil outlet P, and the second throttling device The flow device 164 is located between the third oil return port T1 and the hydraulic oil tank 122 . When working, when the high-pressure oil enters through the third oil inlet P1, it first passes through the first throttling device 163 to throttle and limit the pressure, which can eliminate the pressure shock, and then smoothly enters the second load feedback oil port LS to reduce the start-up shock . After the work is completed, the high-pressure oil is exported from the third oil return port T1 and flows back into the hydraulic oil tank 122 through the second throttling device 164 to throttle and limit the pressure. The second throttling device 164 can realize smooth unloading and eliminate impact. The control system works more stably, has a longer service life, and has higher safety.

Specifically, the floating control mechanism 130 includes a flow stabilizing device 131, a floating control valve 132, a left floating oil cylinder 133 and a right floating oil cylinder 134; the first oil inlet P of the floating control mechanism 130 is located on the flow stabilizing device 131; the floating control mechanism The first oil return port T of 130 is set on the floating control valve 132; the steady flow device 131 also has a second oil outlet P1 connected with the fourth oil inlet P on the floating control valve 132; the floating control valve 132 There are also a third oil outlet A and a fourth oil outlet B, the third oil outlet A is connected with the V1 port of the balance valve of the left floating oil cylinder 133 and the V2 port of the right floating oil cylinder 134 balance valve, and the fourth oil outlet Port B is connected with the V2 port of the balance valve of the left floating oil cylinder 133 and the V1 port of the balance valve of the right floating oil cylinder 134 at the same time.

Preferably, the flow stabilizing device 131 is a speed regulating valve, which is used to stably adjust the passing flow.

Specifically, the high-altitude operation control mechanism 140 includes a main control valve group 141, a main boom telescopic cylinder 142, a main boom luffing cylinder 143, and a turntable rotary motor 144; the second oil inlet P, the second load feedback oil port LS and the second The oil return ports T are all set on the main control valve group 141; the main control valve group 141 also has a proportional reversing valve 145 for the main boom telescopic cylinder, a proportional reversing valve 146 for the main boom luffing cylinder, a proportional reversing valve 147 for the turntable rotation, An overflow valve 148 and a third throttling device 149;

The oil inlet port of the main boom telescopic oil cylinder proportional directional valve 145, the main arm luffing oil cylinder proportional directional valve 146 and the turntable rotary proportional directional valve 147 are connected in parallel with the second oil inlet port P, and the oil return port is connected in parallel with the second oil return port T The proportional reversing valve 145 of the main boom telescopic oil cylinder is provided with a working oil port A1 and a working oil port B1 to respectively connect the rodless chamber and the rod chamber of the main boom telescopic oil cylinder 142; the proportional reversing valve 146 of the main boom luffing cylinder is set There are working oil port A2 and working oil port B2 to respectively connect the rodless cavity and the rod cavity of the main arm luffing cylinder 143; Turntable rotary motor 144;

Working oil port A1, working oil port B1, working oil port A2, working oil port B2, working oil port A3 and working oil port B3 are connected in parallel to the second load feedback oil port LS through a check valve, and the second load feedback The oil port LS is connected to the second oil return port T through the third throttling device 149 . When the oil pressure in the feedback oil circuit where the second load feedback oil port LS is located exceeds the flow rate of the three-way shuttle valve 162, it can flow back to the hydraulic oil tank 122 through the third throttling device 149 to realize smooth unloading, thereby protecting the three-way valve. Shuttle valve 162.

Preferably, the second oil inlet P is connected to the second oil return port T through the overflow valve 148, so that when the hydraulic oil output from the first oil outlet P is more than the oil required for the action, the hydraulic oil can pass through the overflow valve 148 flows back to the hydraulic oil tank 122 to avoid causing a large load on the proportional reversing valve 145 of the main boom telescopic cylinder, the proportional reversing valve 146 of the main boom luffing cylinder and the proportional reversing valve 147 of the turntable rotation, which is beneficial to prolonging the service life of the equipment.

Preferably, in this embodiment, the first throttling device 163 , the second throttling device 164 and the third throttling device 149 are all configured as throttling valve structures.

The example of the present invention also includes an electric control travel handle 101, a closed travel pump 102 and a travel motor 103; the closed travel pump 102 is provided with a third working oil port A, a fourth working oil port B and a swash plate control for controlling the output. Proportional valve; the fifth working oil port A and the sixth working oil port B are provided on the walking motor 103; the controller 110 is electrically connected to the electric control walking handle 101 and the swash plate control proportional valve of the closed walking pump 102; the third working Oil port A is connected to the fifth working oil port A, and the fourth working oil port B is connected to the sixth working oil port B.

The specific working mode of the active floating control system of the chassis in this embodiment is as follows: when operating the walking action, the controller 110 communicates with the active floating working mode through the active floating switching device 150, that is, the first oil outlet P of the variable pump 121 is connected to the steady state. The first oil inlet P of the flow device 131 is connected with the third oil inlet P1 of the sensitive switching device 160. The electric control travel handle 101 controls the closed travel pump 102 and the variable output pressure oil of the swash plate drives the travel motor 103 to rotate. The device 110 directly controls the sensitive switching device 160 so that the variable pump 121 enters constant pressure control (that is, the pump outlet maintains a high-pressure standby state), and when the rear axle of the chassis swings, the floating control mechanism 130 starts to work to realize the stability and safety of the walking process;

When walking is stopped, the electronically controlled walking handle 101 is reset, and the controller 110 disconnects the active floating working mode through the active floating switching device 150, that is, the first oil outlet P of the variable pump 121 and the first oil inlet of the flow stabilization device 131 P and the third oil inlet P1 of the sensitive switching device 160 are disconnected, and the controller 110 controls the sensitive switching device 160 to make the variable pump 121 become a load-sensitive pump and is in a standby state. The active floating circuit has been turned off, the chassis will not be adjusted up and down, and is in a stable state, so that it will not affect the movement of getting on the car, and the operation is comfortable to meet customer needs.

As shown in Figures 1 to 2, the embodiment of the present invention also provides an aerial work platform, including a car body 100, a turntable 200, a jib 300, a working platform and an active floating control system for an underframe; the car body 100 has a front axle 170 , the rear axle 180 and the wheels installed on the front axle 170 and the rear axle 180; the left floating oil cylinder 133 and the right floating oil cylinder 134 are located at the left and right ends of the front axle 170 to adjust the swing of the front axle 170; the turntable 200 rotates through the turntable The motor 144 is installed on the car body 100; the boom 300 is installed on the turntable 200 and is provided with a main boom telescopic cylinder 142 and a main boom luffing cylinder 143 to control the expansion and swing of the boom 300; the working platform is installed on the boom 300 superior.

The above embodiments are explanations of the present invention, but the present invention is not limited to the specific details in the above-mentioned embodiments, and those skilled in the art can make various equivalent substitutions or simple modifications within the scope of the technical concept of the present invention. Should belong to the protection scope of the present invention.

Claims (10)

1. An undercarriage active float control system, comprising: the device comprises a controller (110), a hydraulic power mechanism (120), a floating control mechanism (130), a high-altitude operation control mechanism (140) and an active floating switching device (150);

The controller (110) is electrically connected with the hydraulic power mechanism (120), the floating control mechanism (130) and the aerial work control mechanism (140) and is used for outputting control signals to the hydraulic power mechanism (120), the floating control mechanism (130) and the aerial work control mechanism (140);

The hydraulic power mechanism (120) is connected with the floating control mechanism (130) and the aerial work control mechanism (140) through pipelines and is used for driving the floating control mechanism (130) and the aerial work control mechanism (140);

The active floating switching device (150) is arranged between the hydraulic power mechanism (120) and the floating control mechanism (130) and is used for controlling the on-off of a pipeline between the hydraulic power mechanism (120) and the floating control mechanism (130).

2. the undercarriage active float control system of claim 1 wherein said active float switch means (150) is a solenoid valve or a hydraulic or mechanical valve for controlling the make and break of the connected lines.

3. The chassis active float control system of claim 1, wherein said hydraulic power mechanism (120) comprises a variable displacement pump (121) and a hydraulic oil tank (122);

the variable pump (121) is connected with the hydraulic oil tank (122), a first oil outlet P is formed in the variable pump (121) and is connected with a second oil inlet P formed in the aerial work control mechanism (140), and the first oil outlet P is connected with a first oil inlet P formed in the floating control mechanism (130) through the active floating switching device (150);

And a first oil return port T arranged on the floating control mechanism (130) and a second oil return port T arranged on the overhead working control mechanism (140) are respectively connected with the hydraulic oil tank (122).

4. The undercarriage active float control system of claim 3 further comprising a sensitive switching device (160);

The sensitive switching device (160) comprises an electromagnetic valve (161) and a three-way shuttle valve (162), the electromagnetic valve (161) is a two-position three-way electromagnetic valve and is provided with a third oil inlet P1, a third oil return port T1 and a first working oil port A, the three-way shuttle valve (162) is provided with a second working oil port A, a third load feedback oil port LS1 and a fourth load feedback oil port LS2, the third load feedback oil port LS1 is a one-way input port, and the fourth load feedback oil port LS2 is an output port;

The third oil inlet P1 is connected with a first oil outlet P of the variable pump (121), the third oil return port T1 is connected with a hydraulic oil tank (122), the first working oil port a is connected with a second working oil port a of the three-way shuttle valve (162), the fourth load feedback oil port LS2 is connected with a first load feedback oil port LS of the variable pump (121), and the third load feedback oil port LS1 is connected with a second load feedback oil port LS of the high-altitude operation control mechanism (140).

5. The chassis active floating control system according to claim 4, characterized in that said sensitive switching device (160) is further provided with a first throttling device (163) and a second throttling device (164), said first throttling device (163) being located between the third oil inlet P1 and the first oil outlet P, said second throttling device (164) being located between the third oil return T1 and the hydraulic oil tank (122).

6. The undercarriage active float control system of claim 3 wherein the float control mechanism (130) comprises a flow stabilizer (131), a float control valve (132), a left float cylinder (133) and a right float cylinder (134);

A first oil inlet P of the floating control mechanism (130) is formed in the flow stabilizing device (131); a first oil return port T of the floating control mechanism (130) is arranged on the floating control valve (132); the flow stabilizing device (131) is also provided with a second oil outlet P1 connected with a fourth oil inlet P arranged on the floating control valve (132); the floating control valve (132) is further provided with a third oil outlet A and a fourth oil outlet B, the third oil outlet A is simultaneously connected with a V1 port of a balance valve of the left floating oil cylinder (133) and a V2 port of a balance valve of the right floating oil cylinder (134), and the fourth oil outlet B is simultaneously connected with a V2 port of the balance valve of the left floating oil cylinder (133) and a V1 port of the balance valve of the right floating oil cylinder (134).

7. The undercarriage active float control system of claim 6 wherein the flow stabilizer (131) is a speed regulating valve.

8. The undercarriage active float control system of any one of claims 4-7 wherein the aerial work control mechanism (140) comprises a master control valve block (141), a master arm telescoping cylinder (142), a master arm luffing cylinder (143), and a turret slewing motor (144);

The second oil inlet P, the second load feedback oil port LS and the second oil return port T are all arranged on the main control valve group (141); the main control valve group (141) is also provided with a main arm telescopic oil cylinder proportional reversing valve (145), a main arm luffing oil cylinder proportional reversing valve (146), a rotary table rotary proportional reversing valve (147), an overflow valve (148) and a third throttling device (149);

The oil inlet ends of the main arm telescopic oil cylinder proportional reversing valve (145), the main arm variable amplitude oil cylinder proportional reversing valve (146) and the rotary table rotary proportional reversing valve (147) are connected with a second oil inlet P in parallel, and the oil return ends are connected with a second oil return port T in parallel; the main arm telescopic oil cylinder proportional directional valve (145) is provided with a working oil port A1 and a working oil port B1 to be respectively connected with a rodless cavity and a rod cavity of the main arm telescopic oil cylinder (142); the main arm luffing oil cylinder proportional reversing valve (146) is provided with a working oil port A2 and a working oil port B2 to be respectively connected with a rodless cavity and a rod cavity of the main arm luffing oil cylinder (143); the rotary table rotation proportional reversing valve (147) is provided with a working oil port A3 and a working oil port B3 so as to be connected with a rotary table rotation motor (144);

the second oil inlet P is connected with a second oil return port T through an overflow valve (148); the working oil port A1, the working oil port B1, the working oil port A2, the working oil port B2, the working oil port A3 and the working oil port B3 are connected in parallel to a second load feedback oil port LS through a one-way valve respectively, and meanwhile, the second load feedback oil port LS is connected with a second oil return port T through a third throttling device (149).

9. The chassis active floating control system according to claim 1, further comprising an electrically controlled walking handle (101), a closed walking pump (102) and a walking motor (103); the closed traveling pump (102) is provided with a third working oil port A, a fourth working oil port B and a swash plate control proportional valve for controlling output quantity; a fifth working oil port A and a sixth working oil port B are arranged on the traveling motor (103); the controller (110) is electrically connected with the electric control walking handle (101) and a swash plate control proportional valve of the closed walking pump (102); the third working oil port A is connected with the fifth working oil port A, and the fourth working oil port B is connected with the sixth working oil port B.

10. An aerial work platform, characterized by comprising a vehicle body (100), a turntable (200), an arm support (300), a work platform and the chassis active floating control system of any one of claims 1 to 9; the vehicle body (100) is provided with a front axle (170), a rear axle (180) and wheels arranged on the front axle (170) and the rear axle (180); the rotary table (200) is arranged on the vehicle body (100); the arm support (300) is arranged on the rotary table (200); the working platform is arranged on the arm support (300).