CN116457223A

CN116457223A - Vehicle suspension system

Info

Publication number: CN116457223A
Application number: CN202180074472.XA
Authority: CN
Inventors: 布赖恩·克拉克; 迈尔斯·奥尔顿; 亚历山德罗·法西
Original assignee: Terex South Dakota Inc
Current assignee: Terex South Dakota Inc
Priority date: 2020-11-04
Filing date: 2021-11-04
Publication date: 2023-07-18

Abstract

A fluid suspension system for a land vehicle is provided with an actuator coupled to a chassis and an axle of the land vehicle spaced apart from a pivot connection of the axle. The fluid pressure circuit cooperates with at least one actuator. A controller is in operative communication with the fluid pressure circuit and is programmed to receive an input indicative of a travel speed of the land vehicle. The fluid pressure circuit is regulated in a low speed travel range to restrict fluid flow or reduce fluid pressure to pivot in response to changes in the underlying support surface. To adjust the fluid pressure circuit in the high speed travel range for selectively activating at least one actuator or for high fluid pressure activation of at least one actuator in response to changes in the underlying surface.

Description

Vehicle suspension system

Cross Reference to Related Applications

The present application claims priority from U.S. application Ser. No. 17/477,026, filed on 9/16 of 2021, which is a continuation-in-part application of U.S. application Ser. No. 17/089,016, filed on 11/4 of 2020, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

Various embodiments relate to suspension systems for land vehicles.

Background

U.S. patent 5,447,331 entitled "a Vehicle Axle Oscillation System with Positive Ground Contact (axle swing System with positive ground contact)" to Genie Industries, inc., gini.e., 5, 9, 1995 discloses a fluid suspension system for land vehicles.

Disclosure of Invention

According to at least one embodiment, a fluid suspension system for a land vehicle is provided with at least one actuator adapted to be connected to a chassis and an axle of the land vehicle spaced apart from a pivot connection of the axle. The fluid pressure circuit cooperates with at least one actuator. A controller is in operative communication with the fluid pressure circuit and is programmed to receive an input indicative of a travel speed of the land vehicle. The fluid pressure circuit is closed during the low speed travel range to restrict fluid flow to allow the axle to pivot in response to changes in the underlying support surface. In response to a change in the underlying support surface, the fluid pressure circuit is opened and at least one actuator is selectively activated in the high speed travel range.

According to another embodiment, the axle is further defined as a first axle. The fluid suspension system is also provided with a flow control valve in fluid communication with the fluid pressure circuit and a second axle pivotally connected to the chassis.

According to another embodiment, a solenoid valve is in fluid engagement with a source of pressurized fluid and a flow control valve.

According to another embodiment, the solenoid valve is closed in response to a low speed travel range.

According to another embodiment, the solenoid valve is opened in response to a high speed travel range.

According to another embodiment, the flow restriction is in fluid engagement with a source of pressurized fluid and a flow control valve.

According to another embodiment, the flow restriction is in parallel fluid communication with the solenoid valve.

According to another embodiment, the solenoid valve is a normally open valve.

According to another embodiment, the solenoid valve is a normally closed valve.

According to another embodiment, a land vehicle is provided with a chassis. An axle is pivotally connected to the chassis about a horizontal axis perpendicular to the axle. A pair of wheels are mounted to the axle and are spaced apart by a pivot connection therebetween to support the axle and chassis for travel on an underlying support surface. At least one actuator is connected to the chassis and the axle spaced apart from the pivot connection. The fluid pressure circuit cooperates with at least one actuator. A controller is in operative communication with the fluid pressure circuit and is programmed to receive an input indicative of a travel speed of the land vehicle. The fluid pressure circuit is closed during the low speed travel range to restrict fluid flow to allow the axle to pivot in response to changes in the underlying support surface. The fluid pressure circuit opens and at least one actuator selectively activates in response to a change in the underlying support surface during the high speed travel range.

According to another embodiment, a speed sensor cooperates with the land vehicle to determine a travel speed of the land vehicle and communicates with the controller to provide an input indicative of the travel speed.

According to another embodiment, the axle is further defined as a first axle. The second axle is pivotally connected to the chassis about a horizontal axis perpendicular to the second axle and spaced apart from the first axle. A second pair of wheels is mounted to the second axle and is spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on an underlying support surface. The flow control valve is in fluid communication with the fluid pressure circuit and the second axle.

According to one embodiment, a land vehicle is provided with a chassis. The first axle is pivotally connected to the chassis about a horizontal axis perpendicular to the first axle. The second axle is pivotally connected to the chassis about a horizontal axis perpendicular to the second axle and spaced apart from the first axle. A first pair of wheels is mounted to the first axle and is spaced apart from the pivotal connection of the chassis by the first axle therebetween to support the first axle and the chassis for travel on an underlying support surface. A second pair of wheels is mounted to the second axle and is spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on an underlying support surface. The speed sensor determines a travel speed of the land vehicle. A source of pressurized fluid is provided. The first actuator is coupled to the chassis and the first axle spaced apart from the pivot connection. The second actuator is coupled to the chassis and the first axle, spaced apart from the pivot connection and the first actuator. The flow control valve is in fluid engagement with the second axle. The solenoid valve is in fluid engagement with a source of pressurized fluid and a flow control valve. The flow restriction is in fluid engagement with a pressurized fluid source and a flow control valve. The fluid fit of the flow restriction is in parallel with the solenoid valve. A controller is in operative communication with the solenoid valve and is programmed to receive an input from the speed sensor indicative of a travel speed of the land vehicle. The solenoid valve closes during the low speed travel range to restrict fluid flow to allow the first axle to pivot in response to changes in the underlying support surface. The solenoid valve opens and the first and second actuators are selectively activated in response to changes in the underlying support surface during the high speed travel range.

According to another embodiment, a suspension system for a land vehicle is provided with at least one actuator adapted to be connected to a chassis and an axle of the land vehicle spaced apart from a pivot connection of the axle. The suspension circuit cooperates with at least one actuator. A controller is in operative communication with the suspension loop and is programmed to receive an input indicative of a travel speed of the land vehicle. At least one actuator is selectively activated in the high speed travel range in proportion to the travel speed of the land vehicle in response to a change in the underlying support surface.

According to another embodiment, the at least one actuator further comprises an electromechanical actuator.

According to another embodiment, a fluid suspension system for a land vehicle is provided with at least one actuator adapted to be connected to an axle of the chassis and the land vehicle spaced apart from a pivot connection of the axle. The fluid pressure circuit cooperates with at least one actuator. A controller is in operative communication with the fluid pressure circuit and is programmed to receive an input indicative of a travel speed of the land vehicle. The fluid pressure circuit is regulated during the low speed travel range to restrict fluid flow or reduce fluid pressure to allow the axle to pivot in response to changes in the underlying support surface. The fluid pressure circuit is regulated in the high speed travel range to selectively activate at least one actuator or to perform a high fluid pressure activation of at least one actuator in response to a change in the underlying support surface.

According to another embodiment, the axle is further defined as a first axle. The fluid suspension system is also provided with a flow control valve in fluid engagement with the fluid pressure circuit and a second axle pivotally connected to the chassis.

According to another embodiment, a pressure relief valve is in fluid communication with the solenoid valve and in communication with the controller.

According to another embodiment, a pressure relief valve is in fluid communication between the source of pressurized fluid and the solenoid valve.

According to another embodiment, the controller is programmed to activate the pressure relief valve to reduce the fluid pressure over a speed travel range of 0.4 meters/second or less.

According to another embodiment, the controller is programmed to activate the pressure relief valve to increase the fluid pressure over a speed travel range of 0.13 meters/second or greater.

According to another embodiment, a sequence valve is in fluid engagement with the solenoid valve to block fluid flow at a predetermined pressure.

According to another embodiment, a land vehicle is provided with a chassis. An axle is pivotally connected to the chassis about a horizontal axis perpendicular to the axle. A pair of wheels are mounted to the axle and are spaced apart by a pivot connection therebetween to support the axle and chassis for travel on an underlying support surface. At least one actuator is connected to the chassis and the axle spaced apart from the pivot connection. The fluid pressure circuit cooperates with at least one actuator. A controller is in operative communication with the fluid pressure circuit and is programmed to receive an input indicative of a travel speed of the land vehicle. The fluid pressure circuit is regulated during the low speed travel range to restrict fluid flow or reduce fluid pressure to allow the axle to pivot in response to changes in the underlying support surface. The fluid pressure circuit is regulated in the high speed travel range to selectively activate at least one actuator or to perform a high fluid pressure activation of at least one actuator in response to a change in the underlying support surface.

According to another embodiment, the axle is further defined as a first axle. The land vehicle is also provided with a second axle pivotally connected to the chassis about a horizontal axis perpendicular to the second axle and spaced apart from the first axle. A second pair of wheels is mounted to the second axle and is spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on an underlying support surface. The pressure relief valve is in fluid communication with the fluid pressure circuit and the second axle.

According to another embodiment, a solenoid valve is in fluid engagement with a source of pressurized fluid and a pressure relief valve.

According to another embodiment, a sequence valve is in fluid communication with the solenoid valve to block fluid flow at a predetermined pressure.

According to another embodiment, the axle is further defined as a first axle. The fluid pressure circuit is further provided with a flow control valve in fluid engagement with the fluid pressure circuit and a second axle pivotally connected to the chassis.

According to another embodiment, a land vehicle is provided with a chassis. The first axle is pivotally connected to the chassis about a horizontal axis perpendicular to the first axle. The second axle is pivotally connected to the chassis about a horizontal axis perpendicular to the second axle and spaced apart from the first axle. A first pair of wheels is mounted to the first axle and is spaced apart from the pivotal connection of the chassis by the first axle therebetween to support the first axle and the chassis for travel on an underlying support surface. A second pair of wheels is mounted to the second axle and is spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on an underlying support surface. The speed sensor determines a travel speed of the land vehicle. A source of pressurized fluid is provided. The first actuator is coupled to the chassis and the first axle spaced apart from the pivot connection. The second actuator is coupled to the chassis and the first axle, spaced apart from the pivot connection and the first actuator. The pressure relief valve is in fluid communication with a source of pressurized fluid. The solenoid valve is in fluid engagement with the pressure relief valve. A controller is in operative communication with the pressure relief valve and is programmed to receive an input from the speed sensor indicative of a travel speed of the land vehicle. The pressure relief valve is actuated during the low speed travel range to reduce fluid pressure to allow the axle to pivot in response to changes in the underlying support surface. The pressure relief valve is actuated in response to a change in the underlying support surface over a high speed travel range for high fluid pressure actuation of the first and second actuators.

Drawings

FIG. 1 is a perspective view of an overhead working truck according to one embodiment shown in a partially deployed position;

FIG. 2 is a perspective view of an aerial work vehicle according to another embodiment shown partially deployed;

FIG. 3 is a schematic end view of an axle assembly of a land vehicle according to another embodiment;

FIG. 4 is a schematic end view of another axle assembly of the land vehicle of FIG. 3;

FIG. 5 is a fluid circuit diagram of the land vehicle of FIG. 3 according to one embodiment;

FIG. 6 is an enlarged portion of the fluid circuit diagram of FIG. 5;

FIG. 7 is a fluid circuit diagram of the land vehicle of FIG. 3 according to another embodiment; and is also provided with

Fig. 8 is a fluid circuit diagram of the land vehicle of fig. 3 according to another embodiment.

Detailed Description

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

The overhead hoist assembly is provided with an operating platform on a linkage assembly that pivots and/or translates to raise the operating platform to the overhead worksite. Conventional overhead hoist assemblies include a variety of adjustable structures for elevating the operating platform to a height for performing work operations. The overhead hoist assembly generally includes a stacking linkage assembly. The overhead hoist assembly typically includes an articulating beam assembly, which may be provided by a four bar linkage or an extension lifter type linkage. High-altitude elevator assemblies are typically provided on land vehicles for transporting an operating platform to a worksite.

Fig. 1 illustrates an overhead hoist assembly 20 according to one embodiment. The overhead hoist assembly 20 is a mobile overhead hoist assembly 20 that is a land vehicle that is collapsible for transport on an underlying support surface 22 such as the ground or floor (fig. 1). The overhead hoist assembly 20 may also be towed and transported on a trailer at the rear of the truck. The overhead hoist assembly 20 is deployable by operator control to raise an operator to an overhead worksite. The overhead hoist assembly 20 is discussed with respect to the ground 22. Thus, terms such as upper and lower and other height-related terms relative to the height from the ground 22 should not limit the overhead hoist assembly 20 to a particular application of the ground 22.

The overhead hoist assembly 20 includes a hoist structure that provides significant stability and performance characteristics by elevating workers to an advantageous arrival location while providing stability. The overhead hoist assembly 20 includes a chassis 24 for supporting the overhead hoist assembly 20 on the ground 22 or any supporting surface. The chassis 24 is supported on a plurality of wheels 26 that contact the ground 22. The linkage assembly 28 is connected to the chassis 24 to extend or retract from the chassis 24. A platform 30 is provided on the linkage assembly 28 to extend or retract from the chassis 24. The platform 30 includes a peripheral rail 32 that extends upwardly from the platform 30 to enclose an operator work area on the platform 30.

The overhead hoist assembly 20 is used to hoist the platform 30 and workers to an overhead work site to perform work operations. The link assembly 28 is a stacking link assembly 28 having a series of pivotally connected stacking links 34 that collapse to fold and stack on the chassis 24 for compact storage and transport. The overhead hoist assembly 20 also includes an actuator assembly 36 for extending and retracting the linkage assembly 28 and thus the platform 30.

Fig. 2 illustrates an overhead hoist assembly 38 according to another embodiment. The overhead hoist assembly 38 includes a chassis 40 for supporting the overhead hoist assembly 38 on the ground 22. The chassis 40 is supported on a plurality of wheels 42 that contact the ground 22 for supporting and moving the overhead hoist assembly 38. The linkage assembly 44 is connected to the chassis 40 to extend and retract from the chassis 40. A platform 46 is provided on the linkage assembly 44 and has an outer peripheral rail 48. The balustrade assembly 44 includes a plurality of four bar linkages 50 having telescoping beams 52. The actuator assembly 54 is configured to pivot the four-bar linkage 50 and the telescoping beam 52. The actuator assembly 56 is arranged to extend the beam 52.

FIG. 3 illustrates an end view of an axle assembly 58 of the land vehicle 20, which may be a rear axle assembly 58 according to one embodiment. Fig. 4 shows an end view of an axle assembly 60 of the land vehicle 20, which may be a front axle assembly 60. The chassis 24 is supported on a pair of axle assemblies 58, 60. The chassis 24 is pivotally connected to a rear axle 62 of the rear axle assembly 58 at a rear pivot pin 64. The rear pivot pin 64 is centrally located on the rear axle 62 and is horizontally oriented in the fore-aft direction of travel of the land vehicle 20 perpendicular to the rear axle 62. The chassis 24 is pivotally connected to a front axle 66 of the front axle assembly 60 at a front pivot pin 68. The front pivot pin 68 is centrally located on the front axle 66 and is also horizontally oriented in the fore-aft direction of travel of the land vehicle 20 perpendicular to the front axle 66. The front axle assembly 60 may be steerable as is known in the art. The wheels 26 are mounted for rotation on the axle assemblies 58, 60 to support the axle assemblies 58, 60 on the ground 22. Some or all of the wheels 26 may be driven by one or more motors as is known in the art.

The pivoting of the axle assemblies 58, 60 allows the suspension of the land vehicle 20 to maintain the wheels 26 in contact with the ground 22 as the wheels 26 ride over uneven portions of the ground 22. The pivoting axle assemblies 58, 60 are commonly referred to as a swing suspension system. One function of the oscillating suspension system is to maintain ground contact normal forces to prevent loss of traction. Another function of the oscillating suspension system is to lock the axle in place when movement would reduce the stability of the vehicle. Another function of the swing suspension system is to prevent any of the wheels 26 from lifting significantly off the ground 22, which is undesirable because changes in terrain can result in a swing onto a lifted wheel 26 when the projected center of gravity crosses the diagonal between the wheels 26 on opposite corners of the land vehicle 20.

The pivoting of the rear axle assembly 58 is limited to a range of angular pivoting. For example, the rear axle assembly 58 may be allowed to pivot approximately 1 degree in either angular direction. Hard stops 70, 72 are provided on the chassis 24 and extend toward the rear axle 62. As the rear axle assembly 58 approaches an uneven portion on the ground 22, the rear axle 62 may pivot in either direction until it contacts the hard stops 70, 72, thereby limiting the range of pivoting of the pivot. The suspension system cooperates with the front and rear axle assemblies 58, 60 to adjust the front axle assembly 60 in response to pivoting of the rear axle assembly 58. This adjustment may be coordinated to pivot the front axle 66 in opposite angular directions to maintain the tires 26 in contact with the ground when one of the stops 70, 72 is engaged by the rear axle 62.

The pivoting of the rear axle 62 in either the right or left pivoting direction is sensed by the suspension system. The input link 74 is pivotally connected to the rear axle 62 to translate as the rear axle 62 pivots. The input link 74 cooperates with the suspension system such that translation of the input link 74 is detected by the suspension system.

Fig. 5 shows a portion of a suspension system 76 in a circuit diagram. According to one embodiment, the suspension system 76 is a fluid suspension system 76. According to another embodiment, the suspension system 76 is a hydraulic suspension system 76. The hydraulic suspension system 76 receives pressurized hydraulic fluid from a functional manifold 78. The feed line 80 provides fluid communication of hydraulic fluid from the functional manifold 78 to the hydraulic suspension system 76.

Referring to fig. 5, the hydraulic suspension system 76 includes a flow control valve, referred to as a swing valve 82. The input link 74 of the rear axle assembly 58 of fig. 3 is connected to a swing valve 82. The swing valve 82 detects the pivoting direction of the rear axle 62 based on the translation of the input link 74. The swing valve 82 is a directional control valve unit having a neutral partially extended position when the rear axle 62 is in the rest position. In this neutral position, the swing valve 82 does not direct fluid flow. The input link 74 further extends to indicate a pivoting direction, allowing flow in one direction. Retraction of the input link 74 from the neutral position indicates pivoting in the opposite direction, allowing fluid flow in the other direction. Although one input link 74 is shown and described, any number of input links 74 may be employed.

Referring again to FIG. 4, a pair of actuators 84, 86 are provided on the front axle 66. According to one embodiment, the actuators 84, 86 are hydraulic cylinder actuators 84, 86. The hydraulic cylinder actuators 84, 86 are each pivotally connected to the front axle 66 and the chassis 24, and the actuators 84, 86 are spaced apart by the chassis 24 therebetween. According to another embodiment, the actuators 84, 86 are each electromechanical actuators, such as ball screw assemblies or the like. According to another embodiment, any number of actuators 84, 86 may be employed, such as one actuator.

Referring again to fig. 5, the swing valve 82 controls flow between the functional manifold circuit 78 and a swing cylinder circuit 88, 90 that cooperates with one of the hydraulic cylinder actuators 84, 86, respectively. The oscillating cylinder circuits 88, 90 are shown in more detail in fig. 6. The swing cylinder circuits 88, 90 each include a pair of lock valves 92, 94, 96, 98. The locking valves 92, 94, 96, 98 are each connected in parallel with a respective check valve 100, 102, 104, 106 located in a bypass line 108, 110, 112, 114. The locking valves 92, 94, 96, 98 are piloted and move to a flow-through position against an incorporated return spring by pressurization of the respective crossover pilot line 116, 118, 120, 122. Relief lines 124, 126, 128, 130 are provided at the spring ends of the lock valves 92, 94, 96, 98 to vent any oil that leaks out of the lock valves 92, 94, 96, 98.

As shown in fig. 5 and 6, flow lines 132, 134 connect the lock valves 92, 94, 96, 98 and the swing valve 82. Referring now to fig. 6, an input flow line 132 is connected to the lock valves 94, 98 and an output flow line 134 is connected to the lock valves 92, 96. Flow lines 136, 138 connect the lock valves 92, 98 to the cylinder ends of the hydraulic cylinder actuators 84, 86. Flow lines 140, 142 connect the rod ends of the hydraulic cylinder actuators 84, 86 to the lock valves 94, 96. In the event of excessive pressure build-up in the system due to abnormal thermal conditions, heat release lines 144, 146, 148, 150 connect lines 136, 140, 142, 138 to lock valves 92, 94, 96, 98, respectively, to fully open lock valves 92, 94, 96, 98 to release excess pressure in hydraulic cylinder actuators 84, 86.

Referring again to fig. 5, the functional manifold 78 is connected to pumps and reservoirs, not shown. The functional manifold 78 includes a pressure relief valve 152 in parallel with the feed line 80. In the depicted embodiment, the relief valve 152 releases 900 pounds per square inch (psi) of hydraulic pressure back to the reservoir within the functional manifold 78.

The swing valve 82, when not in its centered blocking position, serves to connect the pressurized supply line 80 of the functional manifold 78 with either line 132 or 134 in the suspension system 76 and simultaneously connects the send-out line 154 to the one of the lines 132 or 134 that is not connected to the supply line 80. Referring again to fig. 6, when line 132 is pressurized, check valves 102, 106 unseat and pressurized fluid flows through bypass lines 110, 114 and lines 140, 138 to retract cylinder actuator 84 and extend cylinder actuator 86. At the same time, flow from line 132 passes through the crossover pilot lines 116, 120 to open the lock valves 92, 96. When this occurs, fluid in the cylinder end of the cylinder actuator 84 and fluid in the rod end of the cylinder actuator 86 return along lines 136, 142 and 134 to the swing valve 82 (fig. 5) and the send-out line 154 (see also fig. 5). Simultaneously and referring again to fig. 6, the rod end of the hydraulic cylinder actuator 84 is filled with a line 140, causing the hydraulic cylinder actuator 84 to retract as the hydraulic cylinder actuator 86 extends.

When the pendulum valve 82 is moved in the opposite direction such that line 134 is connected to the in-line 80 through the pendulum valve 82 instead of to the out-line 154 and such that line 134 is connected to the out-line 154 through the pendulum valve 82 instead of to the in-line 80, the result is that the check valves 100, 104 unseat and pressurized fluid flows through the bypass lines 108, 112 and lines 136, 142 to extend the cylinder actuator 84 and retract the cylinder actuator 86. At the same time, flow from line 134 passes through the crossover pilot lines 118, 122 to open the lock valves 94, 98. When this occurs, fluid in the rod end of the hydraulic cylinder actuator 84 and fluid in the cylinder end of the hydraulic cylinder actuator 86 return along lines 140, 138 and line 132 to the swing valve 82 (fig. 5) and the send-out line 154 (see also fig. 5). Simultaneously and referring again to fig. 6, the cylinder end of the hydraulic cylinder actuator 84 is filled with a line 136, thereby extending the hydraulic cylinder actuator 84 as the hydraulic cylinder actuator 86 contracts.

The hydraulic suspension system 76 is adapted to control the axle actuators 84, 86 at a particular travel speed. The swing function allows all four wheels 26 to remain in contact with the ground 22 to maintain stability. At low speeds, the axles 62, 66 may move faster than the terrain requires, which may result in the axles 62, 66 moving in a progressive motion, which may cause discomfort to the operator. The progressive movement initiates and amplifies the vehicle dynamics fed back through the swing valve 82 to produce dynamic movements that are uncomfortable to the operator. The low speed may be 1.0 miles per hour (mph) and less or even less, such as 0.5mph and less, 0.4mph and less or 0.3mph and less. In contrast, the maximum speed is typically 4-5mph, depending on the particular suspension system 76.

Low speed control dynamics are created when the retracted hydraulic cylinder actuators 84 or 86 are placed under high load while the land vehicle 20 is traveling very slowly (0.3 mph and below or 0.5mph and below) across an obstacle. When swing valve 82 is open, hydraulic cylinder actuators 84, 86 extend or retract rapidly, but there is a hysteresis delay before swing valve 82 closes again, resulting in a position jump and inertial application to the elevator structure of land vehicle 20. When the land vehicle 20 is traveling at high speeds (greater than 0.3mph or greater than 0.5 mph), the swing motion cannot be significantly faster than the desired motion of the terrain, so that the swing system cannot overshoot and create dynamics while the swing valve 82 remains open. At low travel speeds, the swing exceeds the speed required to follow the terrain, and the swing valve 82 is overshot and closed, and the swing valve 82 then opens again following the forward movement, creating uncomfortable cyclic motion.

Referring again to fig. 5, a suspension controller 156 is provided. The suspension controller 156 is in electrical communication with a vehicle controller 158 of the land vehicle 20. The suspension controller 156 may be included within a vehicle controller 158 according to an alternative embodiment. The vehicle controller 158 provides the vehicle travel speed to the suspension controller 156. The vehicle controller 158 may provide vehicle travel speed from a speed sensor on the land vehicle 20. The land vehicle 20 may employ an open loop control system with a hydrostatic drive to monitor vehicle travel speed. The land vehicle 20 may employ a closed loop control system having a motor speed sensor (e.g., an electric motor drive). The suspension controller 156 is also in electrical communication with the functional manifold 78.

The functional manifold 78 includes a fixed control valve 260 located between the pressure source and the feed line 80. The flow control valve 160, for example, limits flow to 0.5 Gallons Per Minute (GPM) according to one embodiment. The functional manifold 78 also includes a normally open solenoid valve 162 connected in parallel with the flow control valve 160 and in fluid communication with the pressurized fluid source and the feed line 80. The valve 162 is in electrical communication with the controller 156. A pressure control relief valve 164 may also be provided on the feed line 80 between the flow control valve 160, the on-off valve 162, and the swing valve 82 to limit the pressure to 750psi according to one embodiment.

When the land vehicle 20 is traveling in the high speed range, the on-off valve 162 remains in the open position, bypassing the flow control valve 160 and allowing the swing valve 82 to balance the axle assemblies 58, 60 as described above. The pressure source of the hydraulic fluid is about 8 to 9GPM, allowing for a rapid swing response. However, when the land vehicle 20 is traveling in the low-speed travel range, the suspension controller 156 closes the on-off valve 162. When the on-off valve 162 is closed, fluid flowing to the feed line 80 is directed through the flow control valve 160, thereby restricting the flow of hydraulic fluid to 0.5GPM. At a limited flow rate, the balance of the swing valve 82 is slowed to a comfortable rate that matches the travel speed. When the vehicle 20 returns to a high travel speed, the suspension controller 156 stops closing the on-off valve 162, allowing the valve 162 to reopen for unfurled swing balancing.

According to another embodiment, the on-off valve 162 may be a normally closed valve 162 that is opened by the controller 156 during the high speed range of travel.

According to another embodiment, the flow circuit may be proportional to the vehicle travel speed, rather than switching between the two flows.

Fig. 7 illustrates a portion of a suspension system 170 in a circuit diagram according to another embodiment. According to one embodiment, the suspension system 170 is a fluid suspension system 170. According to another embodiment, the suspension system 170 is a hydraulic suspension system 170. The hydraulic suspension system 170 receives pressurized hydraulic fluid from the functional manifold 78 shown in the previous embodiment. The feed line 172 provides fluid communication of hydraulic fluid from the functional manifold 78 to the hydraulic suspension system 170.

The hydraulic suspension system 170 includes a flow control valve, referred to as a swing valve 174. The input link 74 of the rear axle assembly 58 of fig. 3 is connected to a swing valve 174. The swing valve 174 detects the pivoting direction of the rear axle 62 based on the translation of the input link 74. The swing valve 174 is a directional control valve unit having a neutral partially extended position when the rear axle 62 is in the rest position. In this neutral position, the swing valve 174 does not direct fluid flow. The input link 74 further extends to indicate a pivoting direction, allowing flow in one direction. Retraction of the input link 74 from the neutral position indicates pivoting in the opposite direction, allowing fluid flow in the other direction. Although one input link 74 is shown and described, any number of input links 74 may be employed.

The swing valve 174 controls fluid flow between the functional manifold circuit 78 and the respective swing cylinder circuits 88, 90 that cooperate with one of the hydraulic cylinder actuators 84, 86. The oscillating cylinder circuits 88, 90 are shown in more detail in fig. 6. Flow lines 132, 134 connect the lock valves 92, 94, 96, 98 and the swing valve 174 of the swing cylinders 88, 90. The hydraulic suspension system 170 includes a pressure relief valve 176 in parallel with the feed line 172. In the depicted embodiment, the relief valve 176 releases 670psi of hydraulic pressure back to the reservoir within the functional manifold 78.

The swing valve 174, when not in its centered, blocking position, serves to connect the pressurized supply line 172 of the functional manifold 78 with either line 132 or 134 in the suspension system 170, and simultaneously connects the send-out line 178 to the one of the lines 132 or 134 that is not connected to the supply line 172. Referring again to fig. 6, when line 132 is pressurized, check valves 102, 106 unseat and pressurized fluid flows through bypass lines 110, 114 and lines 140, 138 to retract cylinder actuator 84 and extend cylinder actuator 86. At the same time, flow from line 132 passes through the crossover pilot lines 116, 120 to open the lock valves 92, 96. When this occurs, fluid in the cylinder end of the cylinder actuator 84 and fluid in the rod end of the cylinder actuator 86 return along lines 136, 142 and line 134 to the swing valve 174 (fig. 7) and the send-out line 178 (see also fig. 7). Simultaneously and referring again to fig. 6, the rod end of the hydraulic cylinder actuator 84 is filled with a line 140, causing the hydraulic cylinder actuator 84 to retract as the hydraulic cylinder actuator 86 extends.

When the swing valve 174 is moved in the opposite direction such that the line 134 is connected to the in-line 172 through the swing valve 174 instead of the out-line 178 and such that the line 134 is connected to the out-line 178 through the swing valve 174 instead of the in-line 172, the result is that the check valves 100, 104 unseat and pressurized fluid flows through the bypass lines 108, 112 and the lines 136, 142 to extend the cylinder actuator 84 and retract the cylinder actuator 86. At the same time, flow from line 134 passes through the crossover pilot lines 118, 122 to open the lock valves 94, 98. When this occurs, fluid in the rod end of the hydraulic cylinder actuator 84 and fluid in the cylinder end of the hydraulic cylinder actuator 86 return along lines 140, 138 and line 132 to the swing valve 174 (fig. 7) and the send-out line 178 (see also fig. 7). Simultaneously and referring again to fig. 6, the cylinder end of the hydraulic cylinder actuator 84 is filled with a line 136, thereby extending the hydraulic cylinder actuator 84 as the hydraulic cylinder actuator 86 contracts.

The hydraulic suspension system 170 is adapted to balance the land vehicle 20 at a particular speed. The swing function allows all four wheels 26 to remain in contact with the ground 22 to maintain stability. At low speeds, the descent of the suspension system 170 may not follow the vehicle dynamics, which may cause operator discomfort. The low speed may be 0.4 meters per second (m/s) or less or even lower. These low speed control dynamics occur when the retracted hydraulic cylinder actuator 84 or 86 is placed under high load while the land vehicle 20 is traveling very slowly (0.4 m/s and below) over an obstacle. When the swing valve 174 is open, the hydraulic cylinder actuators 84, 86 extend or retract rapidly, but there is a hysteresis delay before the swing valve 174 is closed again, resulting in a position jump and inertia being applied to the elevator structure of the land vehicle 20. When the land vehicle 20 is traveling at high speeds (greater than 0.4 m/s), the swing motion cannot be significantly faster than the desired motion of the terrain, so that the swing system cannot overshoot and create dynamics while the swing valve 174 remains open. At low travel speeds, the swing exceeds the speed required to follow the terrain, and the swing valve 174 is overshot and closed, and the swing valve 174 is then opened again following the forward movement, creating uncomfortable cyclic motion.

Referring again to fig. 7, the hydraulic suspension system 170 is provided with a suspension controller 180. The suspension controller 180 is in electrical communication with the vehicle controller 158 of the land vehicle 20. The suspension controller 180 may be included within the vehicle controller 158 according to an alternative embodiment. The vehicle controller 158 provides the vehicle travel speed to the suspension controller 180. The vehicle controller 158 may provide vehicle travel speed from a speed sensor on the land vehicle 20.

The hydraulic suspension system 170 includes a relief valve 182 located between the feed line 172 and the swing valve 174. The relief valve 182 provides a high pressure, such as equal to 600psi, to the swing valve 174 when the drive speed is high enough to prevent dynamics (e.g., greater than 0.15 m/s). The relief valve 182 provides a reduced pressure to the swing valve 174 at low travel speeds (e.g., 0.4m/s or less), such as a reduced pressure equal to 520psi, to limit dynamics.

Fig. 8 illustrates a portion of a suspension system 190 in a circuit diagram according to another embodiment. According to one embodiment, the suspension system 190 is a fluid suspension system 190. According to another embodiment, the suspension system 190 is a hydraulic suspension system 190. The hydraulic suspension system 190 receives pressurized hydraulic fluid from the functional manifold 78 shown in the previous embodiment. The feed line 192 provides fluid communication of hydraulic fluid from the functional manifold 78 to the hydraulic suspension system 190.

The hydraulic suspension system 190 includes a flow control valve, referred to as a swing valve 194. The input link 74 of the rear axle assembly 58 of fig. 3 is connected to a swing valve 194. The swing valve 194 detects the direction of pivoting of the rear axle 62 based on the translation of the input link 74. The swing valve 194 is a directional control valve unit having a neutral partially extended position when the rear axle 62 is in the rest position. In this neutral position, the swing valve 194 does not direct fluid flow. The input link 74 further extends to indicate a pivoting direction, allowing flow in one direction. Retraction of the input link 74 from the neutral position indicates pivoting in the opposite direction, allowing fluid flow in the other direction. Although one input link 74 is shown and described, any number of input links 74 may be employed.

The swing valve 194 controls flow between the functional manifold circuit 78 and the respective swing cylinder circuits 88, 90 that cooperate with one of the hydraulic cylinder actuators 84, 86. The oscillating cylinder circuits 88, 90 are shown in more detail in fig. 6. Flow lines 132, 134 connect the lock valves 92, 94, 96, 98 and the swing valve 194 of the swing cylinders 88, 90. The hydraulic suspension system includes a sequence valve 196 continuous with the feed line 192. Fluid flow is allowed from port 198 to port 200 until the downstream pressure reaches the 650psi set point. Once the downstream pressure reaches 650psi, the sequence valve 196 blocks the downstream flow and redirects the flow to the send-out line 202 and back to the reservoir within the functional manifold 78.

The swing valve 194, when not in its centered, blocking position, serves to connect the pressurized supply line 192 of the functional manifold 78 with either line 132 or 134 in the suspension system 190 and simultaneously connects the send-out line 202 to the one of the lines 132 or 134 that is not connected to the supply line 192. Referring again to fig. 6, when line 132 is pressurized, check valves 102, 106 unseat and pressurized fluid flows through bypass lines 110, 114 and lines 140, 138 to retract cylinder actuator 84 and extend cylinder actuator 86. At the same time, flow from line 132 passes through the crossover pilot lines 116, 120 to open the lock valves 92, 96. When this occurs, fluid in the cylinder end of the hydraulic cylinder actuator 84 and fluid in the rod end of the hydraulic cylinder actuator 86 return along lines 136, 142 and line 134 to the swing valve 194 (fig. 8) and the send-out line 202 (see also fig. 8). Simultaneously and referring again to fig. 6, the rod end of the hydraulic cylinder actuator 84 is filled with a line 140, causing the hydraulic cylinder actuator 84 to retract as the hydraulic cylinder actuator 86 extends.

When the swing valve 194 is moved in the opposite direction such that the line 134 is connected to the in-line 192 through the swing valve 194 instead of the out-line 202 and such that the line 134 is connected to the out-line 202 through the swing valve 194 instead of the in-line 192, the result is that the check valves 100, 104 unseat and pressurized fluid flows through the bypass lines 108, 112 and the lines 136, 142 to extend the cylinder actuator 84 and retract the cylinder actuator 86. At the same time, flow from line 134 passes through the crossover pilot lines 118, 122 to open the lock valves 94, 98. When this occurs, fluid in the rod end of the hydraulic cylinder actuator 84 and fluid in the cylinder end of the hydraulic cylinder actuator 86 return along lines 140, 138 and line 132 to the swing valve 194 (fig. 8) and the send-out line 202 (see also fig. 8). Simultaneously and referring again to fig. 6, the cylinder end of the hydraulic cylinder actuator 84 is filled with a line 136, thereby extending the hydraulic cylinder actuator 84 as the hydraulic cylinder actuator 86 contracts.

The hydraulic suspension system 190 is adapted to balance the land vehicle 20 at a particular speed. The swing function allows all four wheels 26 to remain in contact with the ground 22 to maintain stability. At low speeds, the descent of the suspension system 190 may not follow the vehicle dynamics, which may cause operator discomfort. The low speed may be 0.4 meters per second (m/s) or less or even lower. These low speed control dynamics occur when the retracted hydraulic cylinder actuator 84 or 86 is placed under high load while the land vehicle 20 is traveling very slowly (0.4 m/s and below) over an obstacle. When the swing valve 194 is open, the hydraulic cylinder actuators 84, 86 extend or retract rapidly, but there is a hysteresis delay before the swing valve 194 is closed again, resulting in a position jump and inertia being applied to the elevator structure of the land vehicle 20. When the land vehicle 20 is traveling at high speeds (greater than 0.4 m/s), the swing motion cannot be significantly faster than the desired motion of the terrain, so that the swing system cannot overshoot and create dynamics while the swing valve 194 remains open. At low travel speeds, the swing exceeds the speed required to follow the terrain, and the swing valve 194 is overshot and closed, and the swing valve 194 then opens again following the forward movement, creating an uncomfortable cyclic motion.

Referring again to fig. 8, the hydraulic suspension system 190 is provided with a suspension controller 204. The suspension controller 204 is in electrical communication with the vehicle controller 158 of the land vehicle 20. The suspension controller 204 may be included within the vehicle controller 158 according to an alternative embodiment. The vehicle controller 158 provides the vehicle travel speed to the suspension controller 204. The vehicle controller 158 may provide vehicle travel speed from a speed sensor on the land vehicle 20.

The hydraulic suspension system 190 includes a relief valve 206 located between the feed line 192 and the swing valve 194. The relief valve 206 provides a high pressure, such as equal to 600psi, to the swing valve 194 when the drive speed is high enough to prevent dynamics (e.g., greater than 0.15 m/s). The relief valve 206 provides a reduced pressure to the swing valve 194 at low travel speeds (e.g., 0.4m/s or less), such as a reduced pressure equal to 520psi, to limit dynamics.

While various embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Furthermore, the features of the various practical embodiments may be combined to form further embodiments of the invention.

Claims

1. A fluid suspension system for a land vehicle, comprising:

at least one actuator adapted to be connected to a chassis and an axle of the land vehicle spaced apart from a pivot connection of the axle;

a fluid pressure circuit coupled to the at least one actuator; and

a controller in operative communication with the fluid pressure circuit and programmed to:

receiving an input indicative of a travel speed of the land vehicle;

adjusting the fluid pressure circuit to limit fluid flow or reduce fluid pressure during a low speed range of travel to allow the axle to pivot in response to changes in the underlying support surface; and is also provided with

In response to a change in the underlying support surface, the fluid pressure circuit is adjusted in a high speed travel range for selectively activating the at least one actuator or for high fluid pressure activation of the at least one actuator.

2. The fluid suspension system of claim 1, wherein the axle is further defined as a first axle, and

wherein the fluid suspension system further comprises: a flow control valve is in fluid engagement with the fluid pressure circuit and a second axle pivotally connected to the chassis.

3. The fluid suspension system of claim 2, further comprising: a solenoid valve in fluid engagement with a source of pressurized fluid and the flow control valve.

4. The fluid suspension system of claim 3, further comprising: a pressure relief valve in fluid communication with the solenoid valve and in communication with the controller.

5. The fluid suspension system of claim 4, wherein the pressure relief valve is in fluid communication between a source of pressurized fluid and the solenoid valve.

6. The fluid suspension system of claim 4, wherein the controller is programmed to: the pressure reducing valve is actuated to reduce the fluid pressure in a speed travel range of 0.4 m/s or less.

7. The fluid suspension system of claim 4, wherein the controller is programmed to: the pressure reducing valve is actuated to increase the fluid pressure in a speed travel range of 0.13 m/s or more.

8. The fluid suspension system of claim 3, further comprising a sequence valve in fluid engagement with the solenoid valve to block fluid flow at a predetermined pressure.

9. A land vehicle, comprising:

a chassis;

an axle pivotally connected to the chassis about a horizontal axis perpendicular to the axle;

A pair of wheels mounted to the axle and spaced apart by a pivot connection therebetween to support the axle and the chassis for travel on an underlying support surface;

at least one actuator connected to the chassis and the axle spaced apart from the pivot connection;

a fluid pressure circuit coupled to the at least one actuator; and

receiving an input indicative of a travel speed of the land vehicle;

10. The land vehicle of claim 9, further comprising a speed sensor that cooperates with the land vehicle to determine the travel speed of the land vehicle, and the speed sensor communicates with the controller to provide the input indicative of the travel speed.

11. The land vehicle of claim 9, wherein the axle is further defined as a first axle, wherein the land vehicle further comprises:

a second axle pivotally connected to the chassis about a horizontal axis perpendicular to the second axle and spaced apart from the first axle;

a second pair of wheels mounted to the second axle and spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on the lower support surface; and

a pressure relief valve fluidly coupled to the fluid pressure circuit and the second axle.

12. The land vehicle of claim 11, further comprising: a solenoid valve in fluid engagement with a source of pressurized fluid and the pressure relief valve.

13. The land vehicle of claim 12, further comprising a sequence valve in fluid engagement with the solenoid valve to block fluid flow at a predetermined pressure.

14. The land vehicle of claim 9, wherein the axle is further defined as a first axle, and

wherein the fluid pressure circuit further comprises: a flow control valve is in fluid engagement with the fluid pressure circuit and a second axle pivotally connected to the chassis.

15. The land vehicle of claim 14, further comprising: a solenoid valve in fluid engagement with a source of pressurized fluid and the flow control valve.

16. The land vehicle of claim 15, further comprising: a pressure relief valve in fluid communication with the solenoid valve and in communication with the controller.

17. The land vehicle of claim 16, wherein the pressure relief valve is in fluid communication between a source of pressurized fluid and the solenoid valve.

18. The land vehicle of claim 16, wherein the controller is programmed to: the pressure reducing valve is actuated to reduce the fluid pressure in a speed travel range of 0.4 m/s or less.

19. The land vehicle of claim 16, wherein the controller is programmed to activate the pressure relief valve to increase fluid pressure over a speed travel range of 0.13 meters/second or greater.

20. A land vehicle, comprising:

a chassis;

a first axle pivotally connected to the chassis about a horizontal axis perpendicular to the first axle;

A first pair of wheels mounted to the first axle and spaced apart from the pivotal connection of the chassis by the first axle therebetween to support the first axle and the chassis for travel on an underlying support surface;

a second pair of wheels mounted to the second axle and spaced apart from the pivotal connection of the chassis by the second axle therebetween to support the second axle and the chassis for travel on the lower support surface;

a speed sensor for determining a travel speed of the land vehicle;

a source of pressurized fluid;

a first actuator connected to the chassis and the first axle spaced apart from the pivot connection;

a second actuator connected to the chassis and the first axle, spaced apart from the pivot connection and the first actuator;

a pressure relief valve in fluid communication with the source of pressurized fluid;

a solenoid valve in fluid engagement with the pressure relief valve; and

a controller in operative communication with the pressure relief valve and programmed to:

receiving an input from the speed sensor indicative of the travel speed of the land vehicle;

actuating the pressure relief valve to reduce fluid pressure during a low speed range of travel to allow the axle to pivot in response to changes in the underlying support surface; and is also provided with

In response to a change in the underlying support surface, actuating the pressure relief valve in a high speed travel range for high fluid pressure actuation of the first and second actuators.

21. The land vehicle of claim 20, wherein the controller is programmed to: the pressure reducing valve is actuated to reduce the fluid pressure in a speed travel range of 0.4 m/s or less.

22. The land vehicle of claim 20, wherein the controller is programmed to activate the pressure relief valve to increase fluid pressure over a speed travel range of 0.13 meters/second or greater.

23. A fluid suspension system for a land vehicle, comprising:

a fluid pressure circuit coupled to the at least one actuator; and

receiving an input indicative of a travel speed of the land vehicle;

closing the fluid pressure circuit to restrict fluid flow during a low speed travel range to allow the axle to pivot in response to changes in the underlying support surface; and is also provided with

Opening the fluid pressure circuit for selectively activating the at least one actuator in a high speed travel range in response to a change in the underlying support surface.

24. The fluid suspension system of claim 23, wherein the axle is further defined as a first axle, and

25. The fluid suspension system of claim 24, further comprising: a solenoid valve in fluid engagement with a source of pressurized fluid and the flow control valve.

26. The fluid suspension system of claim 25, wherein the solenoid valve closes in response to the low speed travel range.

27. The fluid suspension system of claim 26, wherein the solenoid valve opens in response to the high speed travel range.

28. The fluid suspension system of claim 25, further comprising: a flow restriction in fluid engagement with the pressurized fluid source and the flow control valve.

29. The fluid suspension system of claim 28, wherein the flow restriction is in parallel fluid communication with the solenoid valve.

30. The fluid suspension system of claim 25, wherein the solenoid valve is a normally open valve.

31. The fluid suspension system of claim 25, wherein the solenoid valve is a normally closed valve.

32. A land vehicle, comprising:

a chassis;

a fluid pressure circuit coupled to the at least one actuator; and

receiving an input indicative of a travel speed of the land vehicle;

33. The land vehicle of claim 32, further comprising a speed sensor that cooperates with the land vehicle to determine the travel speed of the land vehicle, and the speed sensor communicates with the controller to provide the input indicative of the travel speed.

34. The land vehicle of claim 33, wherein the axle is further defined as a first axle, wherein the land vehicle further comprises:

a flow control valve in fluid engagement with the fluid pressure circuit and the second axle.

35. The land vehicle of claim 34, further comprising: a solenoid valve in fluid engagement with a source of pressurized fluid and the flow control valve.

36. The land vehicle of claim 35, further comprising: a flow restriction in fluid engagement with the pressurized fluid source and the flow control valve.

37. The land vehicle of claim 36, wherein the flow restriction is in parallel fluid communication with the solenoid valve.

38. A land vehicle, comprising:

a chassis;

a speed sensor for determining a travel speed of the land vehicle;

a source of pressurized fluid;

a flow control valve in fluid communication with the second axle;

a solenoid valve in fluid engagement with the pressurized fluid source and the flow control valve;

a flow restriction in fluid engagement with the pressurized fluid source and the flow control valve, the fluid engagement of the flow restriction in parallel with the solenoid valve; and

a controller in operative communication with the solenoid valve and programmed to:

closing the solenoid valve to restrict fluid flow during a low speed travel range to allow the first axle to pivot in response to a change in the underlying support surface; and is also provided with

The solenoid valve is opened and the first and second actuators are selectively activated in a high speed travel range in response to a change in the underlying support surface.