Double-front-axle power-assisted steering system and vehicle

Abstract

The invention provides a double-front-axle power-assisted steering system and a vehicle, and belongs to the technical field of vehicle steering systems.The double-front-axle power-assisted steering system comprises a double-loop power steering gear, an oil tank, a first power-assisted pump, a second power-assisted pump, an emergency pump, an emergency valve, a first power-assisted cylinder and a second power-assisted cylinder, and the first power-assisted cylinder and the second power-assisted cylinder assist the two front axles of the vehicle respectively; the first booster pump provides pressure oil for a first booster cylinder arranged on a first front axle through the double-loop power steering gear, and the second booster pump provides pressure oil for a second booster cylinder arranged on a second front axle through the double-loop power steering gear. The first booster pump and the second booster pump are driven by the output end of a vehicle engine, and the emergency pump is driven by a gear in the power coupling box. When the first booster pump breaks down, the second booster pump can provide assistance for steering, and when the second booster pump breaks down, the emergency pump replaces the second booster pump to work. When the vehicle loses power to slide, the first booster pump and the second booster pump stop working, and the emergency pump is driven by an internal gear of the power coupling box under the inertia effect of the vehicle to continue to provide assistance for the vehicle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vehicle steering system, more particularly, relates to a double front axle power-assisted steering system and vehicle. BACKGROUND

[0002] For large heavy-duty vehicles, there is a high requirement for vehicle carrying capacity. Double front axle vehicles greatly improve the carrying capacity of the vehicle compared to ordinary single front axle vehicles. For example, airport fire trucks, as the airport fire support level increases, 8x8 airport fire trucks with larger liquid carrying capacity are required. 8x8 airport fire trucks are equipped with 4 axles, including double front axles and double rear axles. Higher load requirements also require more steering assistance.

[0003] In the prior art, a double front axle vehicle steering system is disclosed in Chinese patent CN107140013A. In this scheme, a single power cylinder assembly provides assistance to both front axles. At the same time, the hydraulic power circuit system includes an oil tank, an oil tank outlet pipe, an oil pump, a steering gear inlet pipe, a steering gear outlet pipe, a left steering cylinder inlet pipe and a right steering cylinder inlet pipe. When steering, the oil pump pumps oil from the oil tank into the two chambers of the power cylinder to achieve assistance. However, for vehicles with heavy loads, a single power cylinder cannot meet the simultaneous steering assistance of both front axles, and if the oil pump fails, it lacks an emergency assistance system, making it difficult to ensure emergency steering assistance. SUMMARY

[0004] To solve the problems of the prior art, the present application provides a double front axle power-assisted steering system and vehicle, which applies assistance to both front axles through two sets of assistance circuits, ensuring the assistance effect under high load, and ensuring emergency assistance steering when the assistance pump fails, ensuring safe driving.

[0005] To achieve the above object, the technical scheme of the present application provides a double front axle power-assisted steering system, comprising a double-circuit power steering gear, an oil tank, a power-assisted pump one, a power-assisted pump two, an emergency pump, an emergency valve, a power-assisted cylinder one and a power-assisted cylinder two, the power-assisted cylinder one and the power-assisted cylinder two are respectively used for power assistance of two front axles of a vehicle; the double-circuit power steering gear has a circuit one and a circuit two, the circuit one has an oil inlet P1, an oil return T1, a working oil port A1 and a working oil port B1, the circuit two has an oil inlet P2, an oil return T2, a working oil port A2 and a working oil port B2; the emergency valve has an oil inlet P3, an oil inlet P4, a working oil port A3 and an oil return T3; the oil inlet P1 is communicated with the oil tank through the power-assisted pump one, the oil return T1 is communicated with the oil tank, the working oil port A1 and the working oil port B1 are respectively communicated with a rodless cavity and a rod cavity of the power-assisted cylinder one; the oil inlet P3 is communicated with the oil tank through the power-assisted pump two, the oil inlet P4 is communicated with the oil tank through the emergency pump, the working oil port A3 is communicated with the oil inlet P2, the oil return T3 and the oil return T2 are both communicated with the oil tank, the working oil port A2 and the working oil port B2 are respectively communicated with a rodless cavity and a rod cavity of the power-assisted cylinder two; in normal working condition, the oil inlet P3 is communicated with the working oil port A3 and the oil inlet P4 is communicated with the oil return T3, in a failure state of the power-assisted pump two, the oil inlet P4 is communicated with the working oil port A3, the oil inlet P3 and the oil return T3 are both in a blocked state; the power-assisted pump one and the power-assisted pump two are both driven by an output end of an engine of the vehicle, the emergency pump is driven by a gear in a power coupling box of the vehicle.

[0006] In the steering process, the power-assisted cylinder one and the power-assisted cylinder two apply steering assistance to the front axle one and the front axle two, compared with the existing steering assistance provided by a single power-assisted cylinder for two front axles, the scheme of the present application can provide stronger steering assistance, and the assistance can be more evenly distributed to the two front axles, ensuring the steering assistance effect under high load. At the same time, if the power-assisted pump one fails to supply oil, the power-assisted pump two can also ensure the steering assistance in the case of light load or non-stationary steering. If the power-assisted pump two fails to supply oil, the emergency pump can replace the power-assisted pump one to realize assistance. If the engine of the vehicle loses power during driving, causing the power-assisted pump one and the power-assisted pump two to stop working, since the emergency pump is driven by the gear in the power coupling box of the vehicle, and the gear in the power coupling box of the vehicle still rotates under the action of vehicle inertia during the sliding process of the vehicle, the emergency pump can also work to provide hydraulic oil by the double-circuit power steering gear and the power-assisted cylinder two, ensuring that a certain steering assistance can be provided during the sliding process.

[0007] Optionally, the vehicle further comprises a vehicle frame and a steering linkage, the double-circuit power steering gear is mounted on the vehicle frame, the vehicle frame is mounted with a front axle one and a front axle two, the front axle one has an axle housing one and steering knuckle arms one at both ends of the axle housing one, the front axle two has an axle housing two and steering knuckle arms two at both ends of the axle housing two, the output end of the double-circuit power steering gear is drivingly connected with the steering knuckle arms one and the steering knuckle arms two through the steering linkage; the cylinder barrel of the power-assisted cylinder one is hinged to the axle housing one, the output end of the power-assisted cylinder one is hinged to one of the steering knuckle arms one, the cylinder barrel of the power-assisted cylinder two is hinged to the axle housing two, and the output end of the power-assisted cylinder two is hinged to one of the steering knuckle arms two. The power-assisted cylinder one and the power-assisted cylinder two apply power assistance to the front axle one and the front axle two respectively.

[0008] Optionally, the vehicle further comprises a power-assisted cylinder three, the rodless cavity of the power-assisted cylinder three is communicated with the working oil port B1, and the rod cavity of the power-assisted cylinder three is communicated with the working oil port A1; the steering knuckle arms one at both ends of the axle housing one are a left steering knuckle arm one and a right steering knuckle arm one respectively, the steering knuckle arms two at both ends of the axle housing two are a left steering knuckle arm two and a right steering knuckle arm two respectively, the power-assisted cylinder one and the power-assisted cylinder two are located on the same side of the vehicle frame, the output end of the power-assisted cylinder one is hinged to the left steering knuckle arm one, the output end of the power-assisted cylinder two is hinged to the left steering knuckle arm two, the cylinder barrel of the power-assisted cylinder three is hinged to the axle housing two, and the output end of the power-assisted cylinder three is hinged to the right steering knuckle arm two. The power-assisted cylinder one and the power-assisted cylinder three are connected in parallel with each other, both of which are driven by the power-assisted pump one and communicated in the circuit one of the double-circuit power steering gear. That is, the power-assisted pump one simultaneously provides oil pressure for the power assistance of the front axle one and the front axle two.

[0009] Optionally, the vehicle further comprises a power-assisted cylinder four, the rod cavity of the power-assisted cylinder four is communicated with the working oil port A2, and the rodless cavity of the power-assisted cylinder four is communicated with the working oil port B2; the cylinder barrel of the power-assisted cylinder four is hinged to the axle housing one, and the output end of the power-assisted cylinder four is hinged to the right steering knuckle arm one. The power-assisted cylinder two and the power-assisted cylinder four are connected in parallel with each other, both of which are driven by the power-assisted pump two and communicated in the circuit two of the double-circuit power steering gear, and the power-assisted pump two also simultaneously provides oil pressure for the power assistance of the front axle one and the front axle two. At this time, when the power-assisted pump one fails, the power-assisted pump two can also simultaneously apply partial power assistance to the front axle one and the front axle two, and when the power-assisted pump two fails, the emergency pump replaces the power-assisted pump two to simultaneously apply partial power assistance to the front axle one and the front axle two, thereby ensuring the balance of the force received by the front axle one and the front axle two.

[0010] Optionally, a pressure sensor is installed between the oil return port T1 and the oil tank. When the power-assisted pump one fails to supply oil, although the power-assisted pump two can still provide certain power assistance, the overall power assistance decreases, which affects the steering operation. At this time, the oil return pressure of the oil return port T1 will be lower than the set value, and the pressure sensor will send a signal to the vehicle control system to issue an alarm to remind the driver, thereby improving the safety of the steering system.

[0011] Optionally, the double-circuit power steering gear is fixedly connected to the frame in a prone position, the output end of the double-circuit power steering gear extends vertically towards the bottom, and the output end of the double-circuit power steering gear has a steering rocker arm; the steering linkage includes a longitudinal pull rod, a front swing arm, a front axle pull rod, and a front axle linkage located at the bottom end of the front axle; the front axle linkage includes a front axle swing arm, a front axle long transverse pull rod, and a front axle short transverse pull rod, the front axle swing arm is hingedly connected to the bottom of the first axle housing, the front axle swing arm, the left steering knuckle arm, and the right steering knuckle arm all extend towards the rear side of the frame, and the front axle swing arm further has an extension arm parallel to the first axle housing; the two ends of the front axle long transverse pull rod are respectively hingedly connected to the front axle swing arm and the left steering knuckle arm, and the two ends of the front axle short transverse pull rod are respectively hingedly connected to the front axle swing arm and the right steering knuckle arm; the front swing arm is located between the double-circuit power steering gear and the front axle, the front swing arm is hingedly connected to the frame, the two ends of the longitudinal pull rod are respectively hingedly connected to the steering rocker arm and the front swing arm, and the two ends of the front axle pull rod are respectively hingedly connected to the front swing arm and the extension arm. When the vehicle is steering, the output end of the double-circuit power steering gear drives the steering rocker arm to rotate, the steering rocker arm drives the front swing arm to rotate through the longitudinal pull rod, and the front swing arm drives the front axle swing arm to rotate along the first axle housing through the front axle pull rod. When the front axle swing arm rotates, it drives the left steering knuckle arm and the right steering knuckle arm to rotate through the front axle long transverse pull rod and the front axle short transverse pull rod respectively, thereby realizing the steering operation of the front axle.

[0012] Optionally, the front swing arm has a front extension arm, the top end of the front swing arm is hingedly connected to the frame, the bottom end of the front extension arm extends downwards to be flush with the front axle swing arm, one end of the longitudinal pull rod is hingedly connected to the steering rocker arm through a ball hinge, the other end of the longitudinal pull rod is hingedly connected to the middle part of the front extension arm through a ball hinge, one end of the front axle pull rod is hingedly connected to the bottom end of the front extension arm through a ball hinge, and the other end of the front axle pull rod is hingedly connected to the extension arm through a ball hinge. The front axle pull rod can extend to the bottom position of the front axle through the front extension arm extending towards the bottom, so as to transmit power from the bottom of the front axle to the front axle linkage. At this time, the front axle pull rod can be in a substantially horizontal state, which cooperates with the vertically downward extending output end of the double-circuit power steering gear, so that the length of the longitudinal pull rod and the length of the front axle pull rod driving the front axle are as small as possible, thereby reducing the length of the transmission path. The ball hinge mode can avoid the jamming of the two ends of the longitudinal pull rod and the two ends of the front axle pull rod due to changes in height position during operation.

[0013] Optionally, the steering linkage further comprises a second axle linkage at the bottom end of the second front axle, and a front transition drag link, a middle swing arm, a rear transition drag link, a rear swing arm and a second axle drag link sequentially articulated from the front swing arm towards the rear side of the frame, the middle swing arm and the rear swing arm are both articulated with the frame; the second axle linkage comprises a second axle swing arm, a second axle long cross drag link and a second axle short cross drag link, the second axle swing arm is articulated with the bottom of the second axle housing, the second axle swing arm, the left second steering knuckle arm and the right second steering knuckle arm all extend towards the rear side of the frame, the second axle swing arm further has an extension arm two parallel to the second axle housing; the two ends of the second axle long cross drag link are respectively articulated with the second axle swing arm and the left second steering knuckle arm, the two ends of the second axle short cross drag link are respectively articulated with the second axle swing arm and the right second steering knuckle arm, and the end of the second axle drag link away from the rear swing arm is articulated with the extension arm two. When the vehicle is steering, the power is transmitted to the second axle linkage through the front transition drag link, the middle swing arm, the rear transition drag link, the rear swing arm and the second axle drag link. The second axle drag link drives the second axle swing arm to rotate, and the second axle long cross drag link and the second axle short cross drag link drive the left second steering knuckle arm and the right second steering knuckle arm to rotate respectively, so as to realize the synchronous steering operation of the first front axle and the second front axle.

[0014] Optionally, the rear swing arm has a rear extension arm one, the top end of the rear swing arm is articulated with the frame, the bottom end of the rear extension arm one extends downwards to be flush with the second axle swing arm, one end of the second axle drag link is articulated with the bottom end of the rear extension arm one through a spherical hinge, and the other end of the second axle drag link is articulated with the extension arm two through a spherical hinge; the frame is fixedly installed with an extension frame one and an extension frame two extending towards the bottom, the front swing arm is articulated with the extension frame one, the rear swing arm is articulated with the extension frame two, the front swing arm and the rear swing arm are respectively located on the front and rear sides of the first front axle and are at the same height as the first front axle, and the middle swing arm is located on the top of the first front axle. Since the rotation axis of the rear swing arm is horizontal, the articulated position of the rear swing arm and the second axle drag link changes in height during rotation. Since the rotation axis of the second axle swing arm is vertical, the articulated position of the second axle drag link and the second axle swing arm does not change in height during rotation, so that the height positions of the two ends of the second axle drag link change during operation. In order to adapt to this change and avoid being stuck, the two ends of the second axle drag link are articulated through spherical hinges. The front swing arm, the middle swing arm and the rear swing arm form an upwardly arched triangular structure, the front transition drag link and the rear transition drag link can pass around the first front axle from the top and extend to the second front axle, and the bottom end of the front swing arm and the bottom end of the rear swing arm can also be extended to positions flush with the first axle swing arm and the second axle swing arm respectively.

[0015] A vehicle adopts the double front axle power-assisted steering system shown in any one of the above. The two front axles are simultaneously assisted by two sets of power-assisted circuits, ensuring the power-assisted effect under high load, and ensuring emergency power-assisted steering when the power-assisted pump fails, ensuring driving safety.

[0016] The technical scheme of the present application has the following beneficial effects over the prior art:

[0017] The power-assisted pump one and the power-assisted pump two are respectively communicated with the chambers in the power-assisted cylinder one and the power-assisted cylinder two through the circuit one and the circuit two in the double-circuit power steering gear, and the power-assisted cylinder one and the power-assisted cylinder two respectively apply steering assistance to the front axle one and the front axle two during steering, relative to the prior art of providing steering assistance for two front axles through a single power-assisted cylinder, the scheme of the present application can provide stronger steering assistance, and the steering assistance can be more evenly distributed to the two front axles, ensuring the steering assistance effect under high load. At the same time, if the power-assisted pump one fails to supply oil, the power-assisted pump two can also ensure the steering assistance under light load or non-stationary steering. If the power-assisted pump two fails to supply oil, the emergency pump can replace the power-assisted pump two to realize assistance. In addition, if the engine of the vehicle loses power during driving, causing the power-assisted pump one and the power-assisted pump two to stop working, since the emergency pump is driven by the gear in the vehicle power coupling box, and the gear in the vehicle power coupling box still rotates under the action of vehicle inertia during the sliding process, the emergency pump can also work to provide hydraulic oil for the double-circuit power steering gear and the power-assisted cylinder two, ensuring that a certain amount of steering assistance can be provided during the sliding process. In addition, relative to the prior art of applying assistance through one power-assisted cylinder, under the condition of the same total load, the present application can reduce the load of a single power-assisted cylinder and make the force distribution of the transmission rod system more uniform. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 Hydraulic principle diagram of double front axle power-assisted steering system;

[0020] Figure 2 Power structure schematic diagram of emergency pump;

[0021] Figure 3 Top view of installation structure of double front axle power-assisted steering system;

[0022] Figure 4 Hydraulic principle diagram of double front axle power-assisted steering system with four groups of power-assisted cylinders;

[0023] Figure 5 Top view of installation structure of double front axle power-assisted steering system with four groups of power-assisted cylinders;

[0024] Figure 6 Oblique view of transmission structure of front axle one and front axle two;

[0025] Figure 7This is a diagram of the front axle and steering linkage structure for obstacle avoidance.

[0026] Icons: 11. Dual-circuit power steering; 111. Steering arm; 12. Fuel tank; 13. Engine; 14. Power coupling box; 15. Drive shaft; 21. Power steering pump one; 22. Power steering pump two; 23. Emergency pump; 3. Emergency valve; 41. Power steering cylinder one; 42. Power steering cylinder two; 43. Power steering cylinder three; 44. Power steering cylinder four; 5. Chassis; 51. Front axle one; 511. Axle housing one; 512. Left steering knuckle arm one; 513. Right steering knuckle arm one; 52. Front axle two; 521. Axle housing two; 522. Left steering knuckle arm two; 523. Right steering knuckle arm two; 53. Left frame; 54. Right frame; 55. Mounting plate; 6. Pressure sensor; 701. Tie rod; 702. Front control arm; 703. 704. First Axle Tie Rod; 705. First Axle Swing Arm; 706. First Axle Long Cross Tie Rod; 707. First Axle Short Cross Tie Rod; 708. Front Extension Arm 1; 709. Extension Arm 1; 710. Front Transition Tie Rod; 711. Middle Swing Arm; 712. Rear Transition Tie Rod; 713. Rear Swing Arm; 714. Second Axle Tie Rod; 715. Second Axle Long Cross Tie Rod; 716. Second Axle Short Cross Tie Rod; 717. Extension Arm 2; 718. Rear Extension Arm 1; 719. Extension Frame 1; 720. Extension Frame 2; 721. Front Extension Arm 2; 722. Middle Extension Arm 1; 723. Middle Extension Arm 2; 724. Rear Extension Arm 2; 81. Steering Wheel; 82. Steering Column; 83. Angle Transmission; 84. Rotary Driveshaft. Detailed Implementation

[0027] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0028] Example 1:

[0029] This embodiment provides a dual front axle power steering system. In this embodiment, the direction of the vehicle's front is considered the front side, and the direction of the vehicle's rear is considered the rear side. Based on Figures 1 to 3As shown, the double front axle power assisted steering system includes double circuit power steering gear 11, oil tank 12, power assisted pump one 21, power assisted pump two 22, emergency pump 23, emergency valve 3, power assisted cylinder one 41 and power assisted cylinder two 42. Power assisted cylinder one 41 and power assisted cylinder two 42 are respectively used for power assistance of two front axles of the vehicle. Double circuit power steering gear 11 and emergency valve 3 are both existing steering gears and emergency valves 3. Among them, double circuit power steering gear 11 has two circuits, circuit one and circuit two. Circuit one has oil inlet P1, oil return T1, working oil port A1 and working oil port B1. Circuit two has oil inlet P2, oil return T2, working oil port A2 and working oil port B2. The communication state of one circuit and two circuits is controlled and switched by steering wheel 81. When turning left, working oil port A1 is communicated with oil return T1, working oil port B1 is communicated with oil inlet P1, working oil port A2 is communicated with oil return T2, and working oil port B2 is communicated with oil inlet P2. When turning right, working oil port A1 is communicated with oil inlet P1, working oil port B1 is communicated with oil return T1, working oil port A2 is communicated with oil inlet P2, and working oil port B2 is communicated with oil return T2.

[0030] Emergency valve 3 has oil inlet P3, oil inlet P4, working oil port A3 and oil return T3. Oil inlet P1 is communicated with oil tank 12 through power assisted pump one 21, oil return T1 is communicated with oil tank 12, working oil port A1 and working oil port B1 are respectively communicated with the rodless cavity and the rod cavity of power assisted cylinder one 41. Oil inlet P3 is communicated with oil tank 12 through power assisted pump two 22, oil inlet P4 is communicated with oil tank 12 through emergency pump 23, working oil port A3 is communicated with oil inlet P2, oil return T3 and oil return T2 are both communicated with oil tank 12, and working oil port A2 and working oil port B2 are respectively communicated with the rodless cavity and the rod cavity of power assisted cylinder two 42. In normal working state, oil inlet P3 is communicated with working oil port A3 and oil inlet P4 is communicated with oil return T3. In the fault state of power assisted pump two 22, oil inlet P4 is communicated with working oil port A3, and oil inlet P3 and oil return T3 are both in the state of blockage. Power assisted pump one 21 and power assisted pump two 22 are both driven by the output end of vehicle engine 13, and emergency pump 23 is driven by the gear in power coupling box 14 of the vehicle.

[0031] Based on Figure 2 As shown, vehicle engine 13 transmits power to front axle and rear axle through power coupling box 14 and transmission shaft 15, which is the structure of the existing vehicle. Power assisted pump one 21 and power assisted pump two 22 are both directly driven by the output port of vehicle engine 13. When vehicle engine 13 is turned off, power assisted pump one 21 and power assisted pump two 22 stop operating synchronously. The power input end of emergency pump 23 is connected with the gear shaft in power coupling box 14. When the vehicle is turned off and slides under inertia, the gear in power coupling box 14 still rotates under the action of vehicle inertia, so that emergency pump 23 can still operate under the sliding state of vehicle engine 13 being turned off.

[0032] In this embodiment, based on Figure 3 and Figure 6 As shown in the figure, it also includes a frame 5 and a steering linkage, the double-circuit power steering gear 11 is installed on the frame 5, the frame 5 is installed with a front axle one 51 and a front axle two 52, the front axle one 51 has an axle housing one 511 and steering knuckle arms one at both ends of the axle housing one 511, the front axle two 52 has an axle housing two 521 and steering knuckle arms two at both ends of the axle housing two 521, the output end of the double-circuit power steering gear 11 is drivingly connected with the steering knuckle arms one and the steering knuckle arms two through the steering linkage. The double-circuit power steering gear 11 is driven by a steering wheel 81, the power of the steering wheel 81 is transmitted to the input end of the double-circuit power steering gear 11 through a steering column 82, an angle driver 83 and a rotating transmission shaft 84. The cylinder barrel of the power cylinder one 41 is hinged with the axle housing one 511, the output end of the power cylinder one 41 is hinged with one of the steering knuckle arms one, the cylinder barrel of the power cylinder two 42 is hinged with the axle housing two 521, and the output end of the power cylinder two 42 is hinged with one of the steering knuckle arms two. Specifically in this embodiment, the two steering knuckle arms one are a left steering knuckle arm one 512 and a right steering knuckle arm one 513, and the two steering knuckle arms two are a left steering knuckle arm two 522 and a right steering knuckle arm two 523, the output end of the power cylinder one 41 is hinged with the left steering knuckle arm one 512, and the output end of the power cylinder two 42 is hinged with the left steering knuckle arm two 522. When turning left, the power cylinder one 41 and the power cylinder two 42 contract, and when turning right, the power cylinder one 41 and the power cylinder two 42 extend. Of course, according to different actual conditions, the output end of the power cylinder one 41 and the output end of the power cylinder two 42 can be hinged with the right steering knuckle arm one 513 and the right steering knuckle arm two 523 respectively. Correspondingly, when steering, the extension and contraction states of the power cylinder one 41 and the power cylinder two 42 are opposite to this embodiment, and the communication of the rod cavity and the rodless cavity of the two is reversed.

[0033] The working process of the double-front-axle power steering system in this embodiment is as follows:

[0034] When the vehicle is turning left in normal driving state, the double-circuit power steering gear 11 is switched by the steering wheel 81 to make the working oil port A1 communicate with the return oil port T1, the working oil port B1 communicate with the inlet oil port P1, the working oil port A2 communicate with the return oil port T2, and the working oil port B2 communicate with the inlet oil port P2. The hydraulic pump one 21 is driven by the engine 13 to inject hydraulic oil from the oil tank 12 through the inlet oil port P1 and the working oil port B1 into the rod cavity of the hydraulic cylinder one 41, and the hydraulic oil in the rodless cavity of the hydraulic cylinder one 41 is returned to the oil tank 12 through the working oil port A1 and the return oil port T1, so that the hydraulic cylinder one 41 is contracted to drive the front axle one 51 to turn left. The hydraulic pump two 22 is driven by the engine 13 to inject hydraulic oil from the oil tank 12 through the inlet oil port P3, the working oil port A3, the inlet oil port P2 and the working oil port B2 into the rod cavity of the hydraulic cylinder two 42, and the hydraulic oil in the rodless cavity of the hydraulic cylinder two 42 is returned to the oil tank 12 through the working oil port A2 and the return oil port T2, so that the hydraulic cylinder two 42 is contracted to drive the front axle two 52 to turn left, realizing the steering assist of left turning.

[0035] When the vehicle is turning right in normal driving state, the double-circuit power steering gear 11 is switched by the steering wheel 81 to make the working oil port A1 communicate with the inlet oil port P1, the working oil port B1 communicate with the return oil port T1, the working oil port A2 communicate with the inlet oil port P2, and the working oil port B2 communicate with the return oil port T2. The hydraulic pump one 21 is driven by the engine 13 to inject hydraulic oil from the oil tank 12 through the inlet oil port P1 and the working oil port A1 into the rodless cavity of the hydraulic cylinder one 41, and the hydraulic oil in the rod cavity of the hydraulic cylinder one 41 is returned to the oil tank 12 through the working oil port B1 and the return oil port T1, so that the hydraulic cylinder one 41 is extended to drive the front axle one 51 to turn right. The hydraulic pump two 22 is driven by the engine 13 to inject hydraulic oil from the oil tank 12 through the inlet oil port P3, the working oil port A3, the inlet oil port P2 and the working oil port A2 into the rodless cavity of the hydraulic cylinder two 42, and the hydraulic oil in the rod cavity of the hydraulic cylinder two 42 is returned to the oil tank 12 through the working oil port B2 and the return oil port T2, so that the hydraulic cylinder two 42 is extended to drive the front axle two 52 to turn right, realizing the steering assist of right turning.

[0036] The inside of the emergency valve 3 has a two-position four-way spool, a two-position two-way spool, and an oil inlet throttling hole in parallel with the two-position four-way spool. The two oil inlet ports of the two-position four-way spool are respectively communicated with the oil inlet ports P3 and P4, one of the oil outlet ports of the two-position four-way spool is communicated with the working oil port A3, and the other oil outlet port is communicated with the oil inlet port of the two-position two-way spool. The oil outlet port of the two-position two-way spool is communicated with the oil return port T3. The two-position two-way spool is provided with a signal lamp switch. During driving, the emergency valve 3 monitors the flow of the oil inlet port P3 in real time. When the power-assisted pump 22 is working normally, the actual flow of the oil inlet port P3 is greater than the set value, and the pressure difference before and after the oil inlet throttling hole in the emergency valve 3 is large. Under the action of the pressure difference, the spring on one side of the two-position four-way spool in the emergency valve 3 is compressed, so that the oil inlet port P3 is communicated with the working oil port A3, and the hydraulic oil discharged from the emergency pump 23 is communicated with the oil return port T3 through the two-position four-way spool and the two-position two-way spool in the emergency valve 3. A certain pressure is generated when the hydraulic oil flows through the throttling hole of the two-position two-way spool, and the pressure is greater than the spring force, so that the two-position two-way spool moves, the signal lamp switch of the emergency valve 3 is turned off, and the signal lamp is extinguished. When the power-assisted pump 22 loses power due to failure, the flow of the oil inlet port P3 decreases. When the emergency valve 3 detects that the flow of the oil inlet port P3 decreases to below the set value, the pressure difference before and after the oil inlet throttling hole in the emergency valve 3 decreases, and the pressure difference is not enough to overcome the spring force of the two-position four-way spool. The two-position four-way spool remains in the initial state, so that the oil inlet port P4 is communicated with the working oil port A3, the oil inlet port P3 and the oil return port T3 are both in the blocked state, no flow passes through the throttling hole of the two-position two-way spool, and the two-position two-way spool remains in the initial state. The signal lamp switch is closed, and the signal lamp is turned on to remind the driver. At this time, the emergency pump 23 pumps the oil in the oil tank 12 into the oil inlet port P1 through the oil inlet port P4 and the working oil port A3, so as to replace the power-assisted pump 22 to work.

[0037] When the power-assisted pump 21 loses power due to failure, since the power-assisted cylinder 41 and the power-assisted cylinder 42 are respectively used for the steering assistance of the front axle 51 and the front axle 52, even if the power-assisted cylinder 41 cannot provide assistance to the front axle 51, the power-assisted pump 22 can still provide certain assistance to the front axle 52, so that all assistance does not fail. When the front axle 52 turns, it can also provide certain steering assistance to the front axle 51 through the steering linkage, so as to ensure that the vehicle can turn normally and ensure safety. In the embodiment, a pressure sensor 6 is installed between the oil return port T1 and the oil tank 12. When the power-assisted pump 21 fails to supply oil, although the power-assisted cylinder 42 can still provide certain assistance, the decrease in assistance affects the steering operation. At this time, the oil return pressure of the oil return port T1 is lower than the set value, and the pressure sensor 6 sends a signal to the vehicle control system to issue a warning to remind the driver, thereby improving the safety of the steering system.

[0038] If the engine 13 suddenly stalls during driving, the vehicle will slide under the action of inertia, at this time, the power-assisted pump one 21 and the power-assisted pump two 22 lose power at the same time, the flow and pressure of the inlet port P3 decrease, the emergency valve 3 detects the decrease of the flow of the inlet port P3, the two-position four-way spool of the emergency valve 3 automatically switches state under the action of the spring, so that the inlet port P4 is in communication with the working oil port A3, and the inlet port P3 and the return oil port T3 are in a blocked state. During the sliding process of the vehicle, the gears in the power coupling box 14 rotate under the action of inertia, the emergency pump 23 still runs, and the emergency pump 23 can pump the oil in the oil tank 12 into the inlet port P1 through the inlet port P4 and the working oil port A3, and output shaft of the double-circuit power steering gear 11 driven by the rod system and the power-assisted cylinder two 42 to provide steering assistance for the front axle one 51 and the front axle two 52, avoiding the complete failure of the steering assistance.

[0039] Further, based on Figure 3 and Figure 6 It is shown that the frame 5 in the embodiment has a left girder 53 and a right girder 54, and the left girder 53 and the right girder 54 are connected by a certain number of cross beams to form a frame structure of the frame 5. The double-circuit power steering gear 11 is fixedly connected to the frame 5 in a prone position, specifically, a mounting plate 55 is fixed between the left girder 53 and the right girder 54, and the double-circuit power steering gear 11 is fixed on the mounting plate 55. The prone position means that the output end of the double-circuit power steering gear 11 extends vertically towards the bottom, and the output end of the double-circuit power steering gear 11 has a steering rocker arm 111. The steering rod system includes a longitudinal pull rod 701, a front swing arm 702, a one-axle pull rod 703, and a one-axle rod system located at the bottom end of the front axle one 51. The one-axle rod system includes a one-axle swing arm 704, a one-axle long transverse pull rod 705, and a one-axle short transverse pull rod 706, the one-axle swing arm 704 is hinged to the bottom of the axle housing one 511, the one-axle swing arm 704, the left steering knuckle arm one 512, and the right steering knuckle arm one 513 all extend towards the rear side of the frame 5, and the one-axle swing arm 704 also has an extension arm one 708 parallel to the axle housing one 511. The two ends of the one-axle long transverse pull rod 705 are respectively hinged to the one-axle swing arm 704 and the left steering knuckle arm one 512, and the two ends of the one-axle short transverse pull rod 706 are respectively hinged to the one-axle swing arm 704 and the right steering knuckle arm one 513. The front swing arm 702 is located between the double-circuit power steering gear 11 and the front axle one 51, the front swing arm 702 is hinged to the frame 5, the two ends of the longitudinal pull rod 701 are respectively hinged to the steering rocker arm 111 and the front swing arm 702, and the two ends of the one-axle pull rod 703 are respectively hinged to the front swing arm 702 and the extension arm one 708.

[0040] When the vehicle is turning, the output end of the double-circuit power steering gear 11 drives the steering rocker arm 111 to rotate, the steering rocker arm 111 drives the front swing arm 702 to rotate through the vertical pull rod 701, the front swing arm 702 drives the front axle swing arm 704 to rotate along the axle housing one 511 through the axle pull rod 703. When the front axle swing arm 704 rotates, it drives the left steering knuckle arm one 512 and the right steering knuckle arm one 513 to rotate through the front axle long cross pull rod 705 and the front axle short cross pull rod 706 respectively, realizing the steering operation of the front axle one 51.

[0041] Preferably, the front swing arm 702 has a front extension arm one 707, the top end of the front swing arm 702 is hinged to the frame 5, the bottom end of the front extension arm one 707 extends downward to be flush with the front axle swing arm 704, one end of the vertical pull rod 701 is hinged to the steering rocker arm 111 through a ball hinge, the other end of the vertical pull rod 701 is hinged to the middle part of the front extension arm one 707 through a ball hinge, one end of the axle pull rod 703 is hinged to the bottom end of the front extension arm one 707 through a ball hinge, the other end of the axle pull rod 703 is hinged to the extension arm one 708 through a ball hinge. It should be noted that the bottom end of the front extension arm one 707 extends downward to be flush with the front axle swing arm 704, which means that they are at the same height, not completely without height difference. The axle pull rod can extend to the bottom position of the front axle one 51 through the front extension arm one 707 extending downward, so as to transmit power from the bottom of the front axle one 51 to the axle rod system. At this time, the axle pull rod 703 can be generally horizontal. The output end of the downward vertically extending double-circuit power steering gear 11 makes the length of the vertical pull rod 701 and the length of the axle pull rod 703 driving the front axle one 51 as small as possible, reducing the length of the transmission path. The front swing arm 702 is specifically hinged to the side of the right girder 54 facing the left girder 53. When the front swing arm 702 rotates, the height positions of the hinged parts of the vertical pull rod 701 and the axle pull rod 703 change. The output shaft axis of the double-circuit power steering gear 11 and the rotation axis of the front axle swing arm 704 are vertically arranged, so the height positions of the hinged parts of the vertical pull rod 701 and the axle pull rod 703 do not change when rotating, which makes the height positions of the two ends of the vertical pull rod 701 and the two ends of the axle pull rod 703 change during operation. In order to adapt to this change and avoid being stuck, the two ends of the vertical pull rod 701 and the two ends of the axle pull rod 703 are hinged through ball hinges.

[0042] Based on Figure 3 and Figure 6As shown, the steering linkage further comprises a second axle linkage at the bottom end of the second front axle 52, and a front transition drag link 709, a middle swing arm 710, a rear transition drag link 711, a rear swing arm 712 and a second axle drag link 713 sequentially hinged from the front swing arm 702 to the rear side of the vehicle frame 5, the middle swing arm 710 and the rear swing arm 712 are both hinged to the vehicle frame 5, specifically to the side of the right girder 54 facing the left girder 53. The second axle linkage comprises a second axle swing arm 714, a second axle long cross drag link 715 and a second axle short cross drag link 716, the second axle swing arm 714 is hinged to the bottom of the second axle housing 521, the second axle swing arm 714, the left steering knuckle arm 522 and the right steering knuckle arm 523 all extend to the rear side of the vehicle frame 5, the second axle swing arm 714 further has an extension arm 717 parallel to the second axle housing 521. The two ends of the second axle long cross drag link 715 are respectively hinged to the second axle swing arm 714 and the left steering knuckle arm 522, the two ends of the second axle short cross drag link 716 are respectively hinged to the second axle swing arm 714 and the right steering knuckle arm 523, and the end of the second axle drag link 713 away from the rear swing arm 712 is hinged to the extension arm 717.

[0043] When the vehicle is steering, the front swing arm 702 drives the first front axle 51 to rotate through the first axle linkage at the same time, and the front swing arm 702 transmits power to the second axle linkage through the front transition drag link 709, the middle swing arm 710, the rear transition drag link 711, the rear swing arm 712 and the second axle drag link 713. The second axle drag link 713 drives the first axle swing arm 704 to rotate, and the second axle long cross drag link 715 and the second axle short cross drag link 716 drive the left steering knuckle arm 522 and the right steering knuckle arm 523 to rotate respectively, realizing the synchronous steering operation of the second front axle 52 and the first front axle 51.

[0044] Preferably, based on Figure 3 、 Figure 6 and Figure 7 As shown, the rear swing arm 712 has a rear extension arm 718, the top end of the rear swing arm 712 is hinged to the vehicle frame 5, and the bottom end of the rear extension arm 718 extends downward to be flush with the second axle swing arm 714, one end of the second axle drag link 713 is hinged to the bottom end of the rear extension arm 718 through a ball hinge, and the other end of the second axle drag link 713 is hinged to the extension arm 717 through a ball hinge. Similarly, the bottom end of the rear extension arm 718 extends downward to be flush with the second axle swing arm 714, and the flush does not mean no height difference, but means generally at the same height. At this time, the second axle drag link 713 can be generally in a horizontal state. Also, since the rotation axis of the rear swing arm 712 is horizontal, the height position of the hinge between the second axle drag link 713 and the rear swing arm 712 will change when rotating. Since the rotation axis of the second axle swing arm 714 is vertically arranged, the height position of the hinge between the second axle drag link 713 and the second axle swing arm 714 will not change when rotating, which makes the height position of the two ends of the second axle drag link 713 change during operation. In order to adapt to this change and avoid being stuck, ball hinges are used at the two ends of the second axle drag link 713.

[0045] Preferably, the frame 5 is fixedly installed with an extension frame one 719 and an extension frame two 720 extending to the bottom, the front swing arm 702 is hinged to the extension frame one 719, the rear swing arm 712 is hinged to the extension frame two 720, the front swing arm 702 and the rear swing arm 712 are respectively located on the front and rear sides of the front axle one 51 and are at the same height as the front axle one 51, and the middle swing arm 710 is located on the top of the front axle one 51. In this way, the front swing arm 702, the middle swing arm 710 and the rear swing arm 712 form an upwardly arched triangular structure, the front transition pull rod 709 and the rear transition pull rod 711 can pass over the front axle one 51 from the top and extend to the front axle two 52, and at the same time, the bottom ends of the front swing arm 702 and the rear swing arm 712 can be extended to positions flush with the first axle swing arm 704 and the second axle swing arm 714 respectively. At the same time, in the embodiment, the front swing arm 702 is further provided with a front extension arm two 721 extending downward, the middle swing arm 710 is provided with a middle extension arm one 722 and a middle extension arm two 723 extending upward, and the rear swing arm 712 is further provided with a rear extension arm two 724 extending downward. The two ends of the front transition pull rod 709 are respectively hinged to the front extension arm two 721 and the middle extension arm one 722, and the two ends of the rear transition pull rod 711 are respectively hinged to the middle extension arm two 723 and the rear extension arm two 724, so as to realize the hinged connection between the front swing arm 702 and the second axle pull rod 713.

[0046] Embodiment 2:

[0047] The embodiment provides a double-front-axle power-assisted steering system, and is specifically based on the embodiment 1 and further comprising a power-assisted cylinder three 43. Figure 1 and Figure 3 As shown in the figures, a rodless cavity of the power-assisted cylinder three 43 is communicated with the working oil port B1, and a rod cavity of the power-assisted cylinder three 43 is communicated with the working oil port A1. The steering knuckle arms one located at both ends of the axle housing one 511 are respectively a left steering knuckle arm one 512 and a right steering knuckle arm one 513, the steering knuckle arms two located at both ends of the axle housing two 521 are respectively a left steering knuckle arm two 522 and a right steering knuckle arm two 523, the power-assisted cylinder one 41 and the power-assisted cylinder two 42 are located at the same side of the frame 5, an output end of the power-assisted cylinder one 41 is hinged to the left steering knuckle arm one 512, an output end of the power-assisted cylinder two 42 is hinged to the left steering knuckle arm two 522, a cylinder barrel of the power-assisted cylinder three 43 is hinged to the axle housing two 521, and an output end of the power-assisted cylinder three 43 is hinged to the right steering knuckle arm two 523.

[0048] Through the above setting, the embodiment sets one assist cylinder at the front axle one 51 and two assist cylinders at the front axle two 52. Relative to the two assist cylinders in the embodiment 1, it can provide greater assist force, and is suitable for vehicles with higher load. Among them, the assist cylinder one 41 and the assist cylinder three 43 are parallel to each other, both of which are driven by the assist pump one 21 and communicated in the circuit one of the double-circuit power steering gear 11. That is, the assist pump one 21 simultaneously provides oil pressure for the assist force of the front axle one 51 and the front axle two 52. When the assist pump one 21 fails, the oil pressure in the circuit one decreases, and the return oil pressure of the return port T1 will be lower than the set value, and the pressure sensor 6 will send a signal to the vehicle control system to issue an alarm to remind the driver. At the same time, since the assist pump two 22 can still work normally, the assist pump two 22 provides steering assist force for the front axle one 51 and the front axle two 52 through the rod system and the assist cylinder two 42 driven by the output shaft of the double-circuit power steering gear 11, to ensure that the vehicle can steer normally and ensure safety.

[0049] Embodiment 3:

[0050] The embodiment provides a double-front-axle power steering system, which specifically further includes an assist cylinder four 44 on the basis of the embodiment 2. Figure 4 and Figure 5 As shown in the drawings, the rod cavity of the assist cylinder four 44 is communicated with the working oil port A2, and the rodless cavity of the assist cylinder four 44 is communicated with the working oil port B2. The cylinder barrel of the assist cylinder four 44 is hinged with the axle housing one 511, and the output end of the assist cylinder four 44 is hinged with the right knuckle arm one 513. Through the above setting, the embodiment sets two assist cylinders at the front axle one 51 and two assist cylinders at the front axle two 52. Relative to the two assist cylinders in the embodiment 1 and the three assist cylinders in the embodiment 3, it can further provide greater assist force, and is suitable for vehicles with higher load.

[0051] In the embodiment, the assist cylinder one 41 and the assist cylinder three 43 are parallel to each other, both of which are driven by the assist pump one 21 and communicated in the circuit one of the double-circuit power steering gear 11, and the assist pump one 21 simultaneously provides oil pressure for the assist force of the front axle one 51 and the front axle two 52. At the same time, the assist cylinder two 42 and the assist cylinder four 44 are parallel to each other, both of which are driven by the assist pump two 22 and communicated in the circuit two of the double-circuit power steering gear 11, and the assist pump two 22 also simultaneously provides oil pressure for the assist force of the front axle one 51 and the front axle two 52. At this time, when the assist pump one 21 fails, the assist pump two 22 can also simultaneously apply partial assist force to the front axle one 51 and the front axle two 52, and when the assist pump two 22 fails, the emergency pump 23 replaces the assist pump two 22 to simultaneously apply partial assist force to the front axle one 51 and the front axle two 52, to ensure the balance of the force of the front axle one 51 and the front axle two 52.

[0052] Embodiment 4:

[0053] The embodiment provides a vehicle adopting the double front axle power steering system shown in any one of the embodiments 1-3. Steering assistance is provided to the front axle 51 and the front axle 52 by the power cylinder 41 and the power cylinder 42 during steering, compared with the prior art which provides steering assistance to two front axles by a single power cylinder, the scheme of the application can provide stronger steering assistance, and the assistance can be more evenly distributed to the two front axles, ensuring the steering assistance effect under high load. At the same time, if the power pump 21 fails to supply oil, the power pump 22 can also ensure the steering assistance under light load or non-idling steering. If the power pump 22 fails to supply oil, the emergency pump 23 can replace the power pump 21 to realize assistance. If the engine 13 of the vehicle loses power during driving, causing the power pump 21 and the power pump 22 to stop working, since the emergency pump 23 is driven by the gear in the vehicle power coupling box 14, and the gear in the vehicle power coupling box 14 still rotates under the action of inertia during the sliding process of the vehicle, the emergency pump 23 can also work to provide hydraulic oil for the double-circuit power steering device 11 and the power cylinder 42, ensuring that a certain steering assistance can be provided during the sliding process.

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual front axle power assisted steering system characterised in that: The double-circuit power steering gear, oil tank, booster pump one, booster pump two, emergency pump, emergency valve, booster cylinder one and booster cylinder two, the booster cylinder one and the booster cylinder two are used for boosting of two front axles of a vehicle respectively; the double-circuit power steering gear has circuit one and circuit two, the circuit one has oil inlet P1, oil return T1, working oil port A1 and working oil port B1, the circuit two has oil inlet P2, oil return T2, working oil port A2 and working oil port B2; the emergency valve has oil inlet P3, oil inlet P4, working oil port A3 and oil return T3; The oil inlet P1 is communicated with the oil tank through the booster pump one, the oil return T1 is communicated with the oil tank, the working oil port A1 and the working oil port B1 are communicated with the rodless cavity and the rod cavity of the booster cylinder one respectively; the oil inlet P3 is communicated with the oil tank through the booster pump two, the oil inlet P4 is communicated with the oil tank through the emergency pump, the working oil port A3 is communicated with the oil inlet P2, the oil return T3 and the oil return T2 are both communicated with the oil tank, the working oil port A2 and the working oil port B2 are communicated with the rodless cavity and the rod cavity of the booster cylinder two respectively; In normal working condition, the oil inlet P3 is communicated with the working oil port A3 and the oil inlet P4 is communicated with the oil return T3, in the failure state of the booster pump two, the oil inlet P4 is communicated with the working oil port A3, the oil inlet P3 and the oil return T3 are both in the blocking state; the booster pump one and the booster pump two are driven by the output end of the engine of the vehicle, the emergency pump is driven by the gear in the power coupling box of the vehicle.

2. The dual front axle power assisted steering system of claim 1, wherein: The double-circuit power steering gear is installed on the frame, the frame is installed with front axle one and front axle two, the front axle one has axle housing one and steering knuckle arm one at both ends of the axle housing one, the front axle two has axle housing two and steering knuckle arm two at both ends of the axle housing two, the output end of the double-circuit power steering gear is drivingly connected with the steering knuckle arm one and the steering knuckle arm two through the steering linkage; The cylinder barrel of the booster cylinder one is hinged with the axle housing one, the output end of the booster cylinder one is hinged with one of the steering knuckle arms one, the cylinder barrel of the booster cylinder two is hinged with the axle housing two, the output end of the booster cylinder two is hinged with one of the steering knuckle arms two.

3. The dual front axle power assisted steering system of claim 2, wherein: The booster cylinder three is further included, the rodless cavity of the booster cylinder three is communicated with the working oil port B1, the rod cavity of the booster cylinder three is communicated with the working oil port A1; the steering knuckle arms one at both ends of the axle housing one are left steering knuckle arm one and right steering knuckle arm one respectively, the steering knuckle arms two at both ends of the axle housing two are left steering knuckle arm two and right steering knuckle arm two respectively, the booster cylinder one and the booster cylinder two are located on the same side of the frame, the output end of the booster cylinder one is hinged with the left steering knuckle arm one, the output end of the booster cylinder two is hinged with the left steering knuckle arm two, the cylinder barrel of the booster cylinder three is hinged with the axle housing two, the output end of the booster cylinder three is hinged with the right steering knuckle arm two.

4. The dual front axle power assisted steering system of claim 3, wherein: Further include the boost cylinder four, the rod cavity of the boost cylinder four is communicated with the working oil port A2, the rodless cavity of the boost cylinder four is communicated with the working oil port B2;The cylinder of the boost cylinder four is articulated with the axle housing one, the output end of the boost cylinder four is articulated with the right knuckle arm one.

5. The dual front axle power assisted steering system of any one of claims 1-4, wherein: The oil return port T1 is provided with a pressure sensor between the oil tank.

6. The dual front axle power steering system of claim 3, wherein: The double-circuit power steering gear is fixedly connected to the frame in a prone position, the output end of the double-circuit power steering gear extends vertically to the bottom, and the output end of the double-circuit power steering gear has a steering rocker arm. The two ends of the one-bridge long transverse pull rod are respectively articulated with the one-bridge swing arm and the left knuckle arm one, and the two ends of the one-bridge short transverse pull rod are respectively articulated with the one-bridge swing arm and the right knuckle arm one.

7. The dual front axle power steering system of claim 6, wherein: The front swing arm has a front extension arm one, the top end of the front swing arm is articulated with the frame, the bottom end of the front extension arm one extends downward to be flush with the one-bridge swing arm, one end of the vertical pull rod is articulated with the steering rocker arm through a ball hinge, the other end of the vertical pull rod is articulated with the middle part of the front extension arm one through a ball hinge, one end of the one-bridge pull rod is articulated with the bottom end of the front extension arm one through a ball hinge, and the other end of the one-bridge pull rod is articulated with the extension arm one through a ball hinge.

8. The dual front axle power assisted steering system of claim 7, wherein: The steering linkage further includes a two-bridge linkage at the bottom end of the front bridge two, and a front transition pull rod, a middle swing arm, a rear transition pull rod, a rear swing arm and a two-bridge pull rod articulated in sequence from the front swing arm to the rear side of the frame, and the middle swing arm and the rear swing arm are both articulated with the frame. The two ends of the two-bridge long transverse pull rod are respectively articulated with the two-bridge swing arm and the left knuckle arm two, and the two ends of the two-bridge short transverse pull rod are respectively articulated with the two-bridge swing arm and the right knuckle arm two. The end of the two-bridge pull rod away from the rear swing arm is articulated with the extension arm two.

9. The dual front axle power steering system of claim 8, wherein: The rear swing arm has a rear extension arm one, the top end of the rear swing arm is hinged with the frame, the bottom end of the rear extension arm one extends downward to be flush with the two-axle swing arm, one end of the two-axle pull rod is hinged with the bottom end of the rear extension arm one through a ball hinge, the other end of the two-axle pull rod is hinged with the extension arm two through a ball hinge; The frame is fixedly installed with an extension frame one and an extension frame two extending to the bottom, the front swing arm is hinged with the extension frame one, the rear swing arm is hinged with the extension frame two, the front swing arm and the rear swing arm are respectively located on the front and rear sides of the front axle one and are at the same height with the front axle one, and the middle swing arm is located on the top of the front axle one.

10. A vehicle characterized by: The double-front-axle power-assisted steering system is adopted.

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