GB2564763A

GB2564763A - Lockout and roll control valve

Info

Publication number: GB2564763A
Application number: GB1808873.2A
Authority: GB
Inventors: Joyce David; Matthews Josh; P Hamkins Eric
Original assignee: Husco Automotive Holdings LLC
Current assignee: Husco Automotive Holdings LLC
Priority date: 2017-05-31
Filing date: 2018-05-31
Publication date: 2019-01-23
Anticipated expiration: 2038-05-31
Also published as: GB201808873D0; GB2564763B

Abstract

A hydraulic suspension system 100 including a lockup and roll control valve is provided. The hydraulic suspension system 100 includes a first hydraulic actuator 104 having a first cylinder 180 and a first piston 182 received within the first cylinder 180, and a second hydraulic actuator 106 having a second cylinder 190 and a second piston 192 received within the second cylinder 190. The first cylinder 180 defines a first head chamber 186 and a first rod chamber 188, and the second cylinder 190 defines a second head chamber 196 and a second rod chamber 198, there being a first orifice 210 connected between the first head chamber 186 and the second head chamber 196. The hydraulic suspension system 100 further includes at least one control valve 204 configured to selectively provide fluid communication between the first head chamber 186 and the second head chamber 196 through a second orifice 212, the second orifice 212 being arranged in parallel with the first orifice 210, thereby selectively varying a roll stiffness defined between the first hydraulic actuator 104 and the second hydraulic actuator 106, and at least one accumulator 222, 224 connected to the first head chamber 186 and the second head chamber 196.

Description

LOCKOUT AND ROLL CONTROL VALVE

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] The present application is based on, claims to, and incorporates herein by reference in its entirety, United States Provisional Patent Application No. 62/513,132, filed on May 31, 2017, and entitled Lockout and Roll Control Valve.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH [0002] Not Applicable.

BACKGROUND [0003] Generally, off-highway equipment, such as construction and agricultural vehicles, can carry widely varying loads. When a load is applied to the equipment, the vehicle body can be forced downward with respect to the axles supporting the wheels of the vehicle. This, for example, may result in compression of the suspension, which can adversely affect the maneuverability of the vehicle. On the other hand, if the suspension is configured for very heavy loads, the vehicle may have an undesirable ride under light load conditions.

[0004] As a result, for example, many vehicles may employ automatic load leveling systems that employ separate hydraulic cylinders between the axle and the frame on opposite sides of the vehicle. When a heavy load is applied to the frame, the drop of the frame may be sensed and additional hydraulic fluid may be applied to the cylinders to raise the frame to the desired distance from the axle. Thereafter, when that load is removed from the vehicle and the frame rises significantly above the axle, hydraulic fluid can be drained from the cylinders to lower the frame with respect to the axle. This type of automatic hydraulic load leveling system, for example, may ensure that the frame and axle are maintained at a desired separation regardless load applied to the vehicle.

[0005] The suspension may undergo another condition when the vehicle makes a relatively tight turn. At that time, the upper part of the vehicle body may tip outward causing a roll effect that compresses the suspension cylinder on the outside of the turn and extends the cylinder on the inside of the turn. A greater force may be applied to the outside cylinder than is encountered by the inside cylinder. In one configuration of the suspension, fluid in the outside cylinder may be

- 1 forced from the head chamber into the rod chamber of the inside (or opposite) side cylinder. That flow can be restricted because the volume of the rod chamber expands less than the contraction of the head chamber, due the presence of the piston rod in the rod chamber. The restriction may provide resistance to the roll motion. The amount of resistance may be determined by a fixed size of the cylinders, which can be selected based on the characteristics of the vehicle.

[0006] The fixed roll resistance, while being acceptable for many vehicles, is not optimal for vehicles in which the roll forces vary significantly under different operating conditions. For example, an agricultural vehicle may have different attachments and carry differing loads. The roll forces produced with the various load configurations can be significantly different. Therefore, suspension cylinders selected to counter roll for one load configuration may not adequately counter the roll for other load configurations.

BRIEF SUMMARY [0007] The present disclosure relates generally to hydraulic suspension systems and, more specifically, to hydraulic suspension systems configured to counter roll on an off-highway vehicle.

[0008] In one aspect, the present disclosure provides a hydraulic suspension system that includes a first hydraulic actuator having a first cylinder and a first piston slidably received within the first cylinder, and a second hydraulic actuator having a second cylinder and a second piston slidably received within the second cylinder. The first cylinder defines a first head chamber and a first rod chamber, and the second cylinder defines a second head chamber and a second rod chamber. The hydraulic suspension system further includes at least one control valve configured to selectively vary a restriction along a fluid path defined between the first head chamber and the second head chamber, thereby selectively varying a roll stiffness defined between the first hydraulic actuator and the second hydraulic actuator, and at least one accumulator connected to the first head chamber and the second head chamber.

[0009] In another aspect, the present disclosure provides a hydraulic suspension system that includes a first hydraulic actuator having a first cylinder and a first piston slidably received within the first cylinder, and a second hydraulic actuator having a second cylinder and a second piston slidably received within the second cylinder. The first cylinder defines a first head

-2chamber and a first rod chamber, and the second cylinder defines a second head chamber and a second rod chamber. The hydraulic suspension system further includes a first orifice connected between the first head chamber and the second head chamber, at least one control valve configured to selectively provide fluid communication between the first head chamber and the second head chamber through a second orifice, and at least one accumulator connected to the first head chamber and the second head chamber. The second orifice is arranged in parallel with the first orifice.

[0010] The foregoing and other aspects and advantages of the disclosure will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred configuration of the disclosure. Such configuration does not necessarily represent the full scope of the disclosure, however, and reference is made therefore to the claims and herein for interpreting the scope of the disclosure.

BRIEF DESCRIPTION OF DRAWINGS [0011] The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings.

[0012] Fig. 1 illustrates a hydraulic suspension system including a normally open, direct acting proportional spool according to one aspect of the present disclosure.

[0013] Fig. 2 illustrates a hydraulic suspension system including a normally closed, direct acting proportional spool according to one aspect of the present disclosure.

[0014] Fig. 3 illustrates a hydraulic suspension system including an electrohydraulic proportional valve according to one aspect of the present disclosure.

[0015] Fig. 4 illustrates a hydraulic suspension system including a double blocking cartridge according to one aspect of the present disclosure.

[0016] Fig. 5 illustrates a hydraulic suspension system including an a roll control valve according to one aspect of the present disclosure.

-3 DETAILED DESCRIPTION [0017] Before any aspect of the present disclosure are explained in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The present disclosure is capable of other configurations and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.

[0018] The following discussion is presented to enable a person skilled in the art to make and use aspects of the present disclosure. Various modifications to the illustrated configurations will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other configurations and applications without departing from aspects of the present disclosure. Thus, aspects of the present disclosure are not intended to be limited to configurations shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected configurations and are not intended to limit the scope of the present disclosure. Skilled artisans will recognize the non-limiting examples provided herein have many useful alternatives and fall within the scope of the present disclosure.

[0019] Generally, the present disclosure provides a hydraulic suspension system that can include a pair of hydraulic actuators adjacent opposite sides of a vehicle. During a roll, for example, one cylinder can extend and the other can retract. Flow exhausted from the retracting cylinder can be connected to an accumulator, and/or to the head chamber on the opposite side of the vehicle. The opposite head chamber may be connected to a second accumulator. The stiffness of the retracting cylinder can depend, in part, on the restriction to flow out of the head side chamber, and/or to the amount of flow into the accumulators. The suspension can be made

-4stiffer or less stiff by adjusting the restriction to flow between head chambers, or to the accumulators, or both. In some aspects, control valves can be included to “lockout” any accumulators, to achieve the stiffest suspension.

[0020] In some non-limiting examples, the present disclosure provides a hydraulic suspension system that is configured to selectively adjust a roll stiffness between a first hydraulic actuator and a second hydraulic actuator. In this regard, the hydraulic suspension system may include at least one control valve that is configured to vary a restriction between a first head chamber of a first hydraulic actuator and a second head chamber of a second hydraulic actuator. In this way, for example, the hydraulic suspension system may be configured to selectively vary a roll stiffness (i.e., the hydraulic suspension systems stiffness during a roll event) by selectively actuating the at least one control valve.

[0021] Fig. 1 illustrates one non-limiting example of a hydraulic suspension system 100 according to the present disclosure. In the illustrated non-limiting example, the hydraulic suspension system 100 includes a main level control valve 102, a first hydraulic actuator 104, a second hydraulic actuator 106, and a suspension assembly 108. The main level control valve 102 may be in fluid communication with the suspension assembly 108 and may be configured to selectively supply fluid to and remove fluid from the first and second hydraulic actuators 104 and 106. In some non-limiting examples, the first hydraulic actuator 104 and the second hydraulic actuator 106 may be arranged on opposing sides of an off-highway vehicle. For example, the first hydraulic actuator 104 may be arranged between an axle and a vehicle frame on one side of an off-highway vehicle, and the second hydraulic actuator 106 may be arranged between the axel and the vehicle frame on an opposite side of the off-highway vehicle.

[0022] Generally, the main level control valve 102 may be configured to selectively adjust a ride height of the off-highway vehicle by supply fluid to or removing fluid from the first hydraulic actuator 104 and the second hydraulic actuator 106. In the illustrated non-limiting example, the mam level control valve 102 may include a supply conduit 110 and a return conduit 114. The supply conduit 110 may be in fluid communication with a fluid source (e.g., a pump) configured to supply pressurized fluid thereto. In some non-limiting examples, the main level control valve 102 may include a load sense node that may be used to supply a control signal to the fluid source and control, for example, the displacement thereof. The return conduit 114 may be in fluid communication with a reservoir, or tank.

- 5 [0023] A supply control valve 116 may be arranged on the supply conduit 110 that includes a first supply port 118, a second supply port 120, and a third supply port 122. The first supply port 118 may be in fluid communication with the fluid source, the second supply port 120 may be in fluid communication with a supply node 123, and the third supply port may be in fluid communication with the return conduit 114. The supply control valve 116 may be selectively moveable between a first supply position where fluid communication is provided between the second supply port 120 and the third port 122 and the first supply port 118 is blocked, and a second supply position where fluid communication is provided between the first supply port 118 and the second supply port 120 and the third supply port 122 is blocked. The supply conduit 110 may split into a head conduit 124 and a rod conduit 126 at a location the supply node 123.

[0024] The head conduit 124 may include a head component assembly 128 arranged between the supply node 123 and the suspension assembly 108. In some non-limiting examples, the head component assembly 128 may include one or more check valves, one or more orifices, and/or one or more control valves that are configured to control a direction and flow rate of fluid flowing along the head conduit 124. For example, the head component assembly 128 may control whether fluid is supplied along the head conduit 124 in a direction from the supply node 123 toward the first and second hydraulic actuators 104 and 106, or fluid is allowed to flow along the head conduit 124 in a direction from the first and second hydraulic actuators 104 and 106 toward the return conduit 114.

[0025] The rod conduit 126 may include a rod component assembly 130 arranged between the supply node 123 and the suspension assembly 108. In some non-limiting examples, the rod component assembly 130 may include one or more relief valves, one or more check valves, one or more orifices, and/or one or more pilot operated check valves to control a direction and flow rate of fluid along the rod conduit 126. For example, the rod component assembly 130 may control whether fluid is supplied along the rod conduit 126 in a direction from the supply node

123 toward the first and second hydraulic actuators 104 and 106, or fluid is allowed to flow along the rod conduit 126 in a direction from the first and second hydraulic actuators 104 and 106 toward the return conduit 114.

[0026] A head relief valve 132 may provide fluid communication between the head conduit

124 and the return conduit 114 when the pressure in the head conduit 124 increases past a predetermined value. A rod relief valve 134 may provide fluid communication between the rod conduit 126 and the return conduit 114 when the pressure in the rod conduit 126 increases past a predetermined value. A head drain valve 136 and a rod drain valve 138 may enable the suspension assembly 108 to be manually drained to the return conduit 114.

[0027] The first hydraulic actuator 104 may include a first cylinder 180, a first piston 182, and a first rod 184 coupled to the first piston 182. The first piston 182 may be slidably received within the first cylinder 180 and may divide the interior of the first cylinder 180 into a first head chamber 186 and a first rod chamber 188. Similarly, the second hydraulic actuator 106 may include a second cylinder 190, a second piston 192, and a second rod 194 coupled to the second piston 192. The second piston 192 may be slidably received within the second cylinder 190 and may divide the interior of the second cylinder 190 into a second head chamber 196 and a second rod chamber 198.

[0028] In the illustrated non-limiting example, the suspension assembly 108 may include a rod line 200, a head line 202, and at least one control valve 204. The rod line 200 may be in fluid communication with the rod conduit 126 of the main level control valve 102 and may provide fluid communication between the first rod chamber 188 and the second rod chamber 198. A rod accumulator 206 may be in fluid communication with the rod line 200, and thereby with the first rod chamber 188 and the second rod chamber 198. As is known in the art, the rod accumulator 206 may provide a predetermined amount of damping/suspension (e.g., based on the spring/pressure force within the rod accumulator 206) to the first rod chamber 188 and the second rod chamber 198.

[0029] The head line 202 may be in fluid communication with the head conduit 124 of the main level control valve 102 and may provide fluid communication between the first head chamber 186 and the second head chamber 196. A shuttle valve 208 may be arranged on the head line 202 and in fluid communication with the first head chamber 186, the second head chamber 196, and the head conduit 124. The shuttle valve 208 may be configured to communicate a highest pressure between the first head chamber 186 and the second head chamber 196 to the head relief valve 132. For example, when pressurized fluid is flowing out of the first head chamber 186 and/or the second head chamber 196, the shuttle valve 208 may communicate the greatest of the two pressures to the head relief valve 132 along the head conduit 124. In this way, for example, the suspension assembly 108 may be able to protect both chambers of the first hydraulic actuator 104 and the second hydraulic actuator 106 with a single

-7relief valve (i.e., the first head chamber 186 and the second head chamber 196 are protected using a single relief valve (the head relief valve 132)).

[0030] A first orifice 210 may be arranged on the head line 202 that provides a bypass around the shuttle valve 208 (i.e., the first orifice 210 is arranged in parallel with the shuttle valve 208). The first orifice 210 may provide a permanent connection between the first head chamber 186 and the second head chamber 196. In operation, the restricted connection between the first head chamber 186 and the second head chamber 196 through the first orifice 210 may provide roll control (i.e., resistance to vehicle roll occurring during a turn) for the hydraulic suspension system 100. In some non-limiting examples, the connection between the first head chamber 186 and the second head chamber 196 through the first orifice 210 may provide roll control with a roll stiffness (i.e., an stiffness of the spring-like response of the hydraulic suspension system 100 to resist vehicle roll) at a first predetermined value.

[0031] A second orifice 212 may be arranged in parallel with the first orifice 210. Fluid flow through the second orifice 212 may be selectively opened and closed, which varies the restriction to flow between the first head chamber 186 and the second head chamber 196. That is, the parallel combination of the first orifice 210 and the second orifice 212 may define a different effective restriction to flow between the first head chamber 186 and the second head chamber 196 than the restriction to flow provided by only the first orifice 210. In some non-limiting examples, the parallel combination of the first orifice 210 and the second orifice 212 may provide a less restrictive flow path between the first head chamber 186 and the second head chamber 196, when compared to flow through only the first orifice 210. In some non-limiting examples, the parallel combination of the first orifice 210 and the second orifice 212 may provide roll control with a roll stiffness at a second predetermined value that is less that the first predetermined value. In other words, when the parallel path to the second orifice 212 is selectively opened, the roll stiffness defined by the hydraulic suspension system 100 may become softer or decrease.

[0032] In the illustrated non-limiting example, the second orifice 212 may be arranged within the at least one control valve 204. In the illustrated non-limiting example, the at least one control valve 204 is in the form of an electrically-operated proportional control valve that includes a first port 214, a second port 216, a third port 218, and a fourth port 220. The first port 214 may be in fluid communication with the first head chamber 186. The second port 216 may

-8be in fluid communication with the second head chamber 196. The third port 218 may be in fluid communication with a first head accumulator 222, and the fourth port 220 may be in fluid communication with a second head accumulator 224. In the illustrated non-limiting example, the at least one control valve 204 may be proportionally moveable between a first position, a second position, and a third position. In the first position, the at least one control valve 204 may provide a first flow path 228 between the first port 214 and the third port 218 and a second flow path between the second port 216 and the fourth port 220. The second orifice 212 may be connected between the first flow path 228 and the second flow path 230, thereby providing a connection between the first head chamber 186 and the second head chamber 196 that is arranged in parallel with the first orifice 210. In the second position, the at least one control valve 204 provides fluid communication between the first port 214 and the third port 218 and provides fluid communication between the second port 216 and the fourth port 220. In the third position, the at least one control valve 204 blocks all of the first port 214, the second port 216, the third port 218, and the fourth port 220.

[0033] In the illustrated non-limiting example, the at least one control valve 204 may be normally biased into the first position. In other non-limiting examples, as illustrated in Fig. 2, the at least one control valve 204 may be normally biased into the third position. In some nonlimiting examples, the at least one control valve 204 may be proportionally moveable between the first position, the second position, and the third position via a direct-acting solenoid. In some non-limiting examples, the at least one control valve 204 may be proportionally moveable via a manual selection, or via a pilot operated positioning.

[0034] With continued reference to Fig. 1, in operation, the main level control valve 102 may be configured to selectively vary a ride height of an off-vehicle to which the first hydraulic actuator 104 and the second hydraulic actuator 106 are coupled. For example, the main level control valve 102 may supply pressurized fluid from the supply conduit 110 to the first and second head chambers 186 and fluid may be allowed to leave the first and second rod chambers 188 and 198 and flow into the rod accumulator 206 and/or to the return conduit 114, thereby extending the first and second pistons 182 and 192 and raising a ride height of the off-highway vehicle. Alternatively or additionally, the main level control valve 102 may be configured to selectively supply pressurized fluid from the supply conduit 110 to the rod accumulator 206, the first head accumulator 222, and/or the second head accumulator 224.

-9[0035] As described herein, the use of the shuttle valve 208 enables the both of the first head chamber 186 and the second head chamber 196 to be protected using a single relief valve (i.e., the head relief valve 132). The parallel arrangement between the shuttle valve 208 and the first orifice 210 enables the suspension assembly 108 to back-flow the shuttle valve 208 to raise and lower ride height of the off-highway vehicle, as well as provide pressure protection using a single relief valve. For example, the shuttle valve 208 will allow flow into one of the first head chamber 186 and the second head chamber 196, whichever is at the lower pressure, and the connection between the first head chamber 186 and the second head chamber 196 through the first orifice 210 allows the shuttle valve 208 to be bypassed and fill both of the first head chamber 186 and the second head chamber 186. Similarly, the shuttle valve 208 will allow fluid to leave one of the first head chamber 186 and the second head chamber 196, whichever is at the highest pressure, and the connection between the first head chamber 186 and the second head chamber 196 through the first orifice 210 allows the shuttle valve 208 to by bypassed and drain the first head chamber 186 and the second head chamber 196.

[0036] During operation, the at least one control valve 204 may be proportionally moved between the first position, the second position, and the third position to alter the suspension performance of the hydraulic suspension system 100. With the at least one control valve 204 in the first position, the first and second hydraulic actuators 104 and 106 may be fully suspended via the connection between the first and second accumulators 224 and 226 and the first and second head chambers 186 and 196. As is known in the art, the first head accumulator 222 and the second head accumulator 224 may provide a predetermined amount of damping/suspension (e.g., based on the spring/pressure force within the first head accumulator 222 and the second head accumulator 224) to the first head chamber 186 and the second head chamber 196. For example, if the off-highway vehicle encounters a bump while traveling, one or both of the first and second hydraulic actuators 104 and 106 may retract (depending on whether one or both wheels encounter the bump) causing fluid to flow from one or both of the first and second head chambers 186 and 196. The fluid exiting one or both of the first and second head chambers 186 and 196 may be absorbed by one or both of the first and second head accumulators 222 and 224, thereby damping the effects of the bump felt by an operator of the off-highway vehicle.

[0037] In addition to the suspension provided by the connection to the first and second head accumulators 222 and 224, the at least one control valve 204 opens the parallel path between the

- 10first head chamber 186 and the second head chamber 196 through the second orifice 212 in the first position. Thus, fluid may flow between the first head chamber 186 and the second head chamber 196 through the parallel connection of the first orifice 210 and the second orifice 212.

This connection enables the hydraulic suspension system 100 to also provide roll control in addition to the suspension provided by the first and second head accumulators 222 and 224.

[0038] During a roll event, one of the actuators may retract and the other may expand, depending on the direction an off-highway vehicle turns. For example, if the off-highway vehicle turns in one direction, the first hydraulic actuator 104 may retract and the second hydraulic actuator 106 may extend. The retraction of the first hydraulic actuator 104 urges fluid to flow out of the first head chamber 186. The effective restriction provided by the parallel combination of the first orifice 210 and the second orifice 212 may restrict fluid exiting the first head chamber 186 from entering the second head chamber 196. This may force the fluid in the first head chamber 186 to act against or flow into the first head accumulator 222 (depending on the pressure within the first head accumulator 222). Thus, the restricted flow path for fluid exiting the first head chamber 186 counteracts the retraction of the first hydraulic actuator 104 and, thereby, limits the roll of the off-highway vehicle during a roll event.

[0039] When the at least control valve 204 is moved to the second position, the connection between the first and second head chambers 186 and 196 and the first and second head accumulators 222 and 224 remains, however, the parallel path between the first head chamber 186 and the second head chamber 196 through the second orifice 212 is closed. Thus, fluid flow between the first head chamber 186 and the second head chamber 196 may only flow through the first orifice 210. The first orifice 210 may provide a greater restriction to flow between the first head chamber 186 and the second head chamber 196 than the parallel combination of the first orifice 210 and the second orifice 212. As such, moving the at least one control valve 204 between the first position and the second position may vary a restriction along a fluid path between the first head chamber 186 and the second head chamber 196.

[0040] Varying the restriction between the first head chamber 186 and the second head chamber 196 may also vary the roll stiffness defined between the first hydraulic actuator 104 and the second hydraulic actuator 106. For example, during a roll event where the first hydraulic actuator 104 retracts and the at least one control valve 204 is in the second position, fluid exiting the first head chamber 186 may be further restricted from flowing to the second head chamber

- 11 196 than with the at least one control valve 204 in the first position. As such, the roll stiffness may increase, and the roll of the off-highway vehicle may be further limited.

[0041] In this way, for example, the at least one control valve 204 may selectively vary the roll stiffness defined between the first hydraulic actuator 104 and the second hydraulic actuator 106. In some non-limiting examples, the roll stiffness may increase as the at least one control valve 204 is proportionally moved from the first position to the second position. Conversely, as the at least one control valve 204 is proportionally moved from the second position to the first position, the roll stiffness may decrease. Thus, the proportional moveability of the at least one control valve 204 between the first position and the second position enables the selective control of the roll stiffness defined between the first hydraulic actuator 104 and the second hydraulic actuator 106.

[0042] Moving the at least one control valve 204 to the third position may lockout the first and second head chambers 186 and 196 from the first and second head accumulators 222, and the first head chamber 186 and the second head chamber 196 may still be connected through the first orifice 210, which provides roll control with an increased roll stiffness (when compared to the first position). With the first and second head chambers 186 and 196 locked out from the first and second head accumulators 222 and 224, the suspension provided by the hydraulic suspension system 100 may have an increased stiffness (i.e., a reduced damping provided by the spring-like absorption of the accumulators). For example, when the off-highway vehicle encounters a bump with the at least one control valve 204 in the third position, the effects of the bump may not be absorbed by the first and second head accumulators 222 and 224 and transferred from the first and second hydraulic actuators 104 and 106 to the off-highway vehicle. Thus, an operator may experience a stiffer ride when compared to having the first and second head accumulators 222 and 224 connected to the first and second head chambers 186 and 196.

[0043] The proportional moveability of the at least one control valve 204 between the second position and the third position may enable the selective control of the suspension stiffness defined by the first hydraulic actuator 104 and the second hydraulic actuator 106. That is, proportionally moving the at least one control valve 204 between the second position and the third position may vary the suspension stiffness from full lockout (third position) to fully suspended (second position). Thus, the suspension stiffness defined by the first hydraulic actuator 104 and the second hydraulic actuator 106 may be selectively varied between a range of

- 12values (e.g., hard stiffness, medium stiffness, soft stiffness, etc.) depending on the operating conditions of the off-highway vehicle.

[0044] Fig. 3 illustrates another non-limiting example of the hydraulic suspension system 100 according to the present disclosure. Similar components between the hydraulic suspension system of Fig. 3 and the hydraulic suspension system of Fig. 1 are identified using like reference numerals. In the illustrated non-limiting example, the at least one control valve 204 includes a first head control valve 302 and a second head control valve 304. The first head control valve 302 may be arranged between the first head chamber 186 and the first head accumulator 222. The second head control valve 304 may be arranged between the second head chamber 196 and the second head accumulator 224. In the illustrated non-limiting example, the first head control valve 302 and the second head control valve 304 may be an electrohydraulic proportional valve. In some non-limiting examples, at least one of the first head control valve 302 and the second head control valve 304 may be an on/off valve.

[0045] The first head control valve 302 may include a first port 306 and a second port 308, and may be proportionally moveable between a first position and a second position. In the first position, the first head control valve 302 may inhibit fluid flow in a direction from the first head chamber 186 toward the first head accumulator 222 via a first head check valve 310. In the second position, the first head control valve 302 provides fluid communication between the first head chamber 186, the first head accumulator 222, and the second orifice 212.

[0046] The second head control valve 304 may include a first port 312 and a second port 314, and may be moveable between a first position and a second position. In the first position, the second head control valve 304 may inhibit fluid flow in a direction from the second head chamber 196 toward the second head accumulator 224 via a second head check valve 316. In the second position, the second head control valve 304 may provide fluid communication between the second head chamber 196, the second head accumulator 224, and the second orifice 212.

[0047] In the illustrated non-limiting example, the second orifice 212 may be arranged on a connection that extends from between the first head control valve 302 and the first head accumulator 222 to between the second head control valve 304 and the second head accumulator 224.

[0048] A rod control valve 318 may be arranged between the rod accumulator 206 and the rod line 200. The rod control valve 318 may include a first port 320 in fluid communication with

- 13 the rod line 200 and a second port 322 in fluid communication with the rod accumulator 206. The rod control valve 318 may be moveable between a first position where fluid flow is inhibited in a direction from the rod line 200 toward the rod accumulator 206, and a second position where fluid communication is provided between the rod line 200 and the rod accumulator 206. In general, the rod control valve 318 may enable the hydraulic suspension system 100 to maintain a ride height of an off-highway vehicle during after traveling over one or more bumps. For example, while traveling over a bump, one or both of the first hydraulic actuator 104 and the second hydraulic actuator 106 may tend to extend following a retraction due to the bump. The extension may cause fluid to be drawn from the head accumulators into the head chambers, which, after the bump is over, may cause the off-highway vehicle to equilibrate at a higher ride height. However, the rod control valve 318 may selectively inhibit fluid communication from the rod line 200 to the rod accumulator 206, which may prevent the first and second hydraulic actuators 104 and 106 from equilibrating at a higher ride height after the off-highway vehicle travels over a bump.

[0049] The operating characteristics of the hydraulic suspension system of Fig. 3 may be similar to the operating characteristics of the hydraulic suspension system of Fig 1, described above. However, instead of moving the at least one control valve 204 in Fig. 1, the first head control valve 302 and the second head control valve 304 may be proportionally moved between the first position and the second position to control a roll stiffness between the first hydraulic actuator 104 and the second hydraulic actuator 106, as well as the suspension stiffness of the first hydraulic actuator 104 and the second hydraulic actuator 106 provided by the first head accumulator 222 and the second head accumulator 224, respectively. For example, proportionally moving the first head control valve 302 and the second head control valve 304 from the first position to the second position may proportionally open the parallel path between the first head chamber 186 and the second head chamber 196 through the second orifice 212, which may decrease the roll stiffness. In addition, proportionally moving the first head control valve 302 and the second head control valve 304 from the first position to the second position may proportionally open the connection between the first head chamber 186 and the first head accumulator 222 and between the second head chamber 196 and the second head accumulator 224, which decreases the suspension stiffness.

- 14[0050] Fig. 4 illustrates another non-limiting example of the hydraulic suspension system 100 according to the present disclosure. The configuration of Fig. 4 is similar to that of Fig. 3, with similar components identified using like reference numerals, except that first head control valve 302 and the second head control valve 304 are double blocking in the first position. That is, the first head control valve 302 may include the first head check valve 310 and a second head check valve 400 in the first position, which block fluid flow in both directions. The second head control valve 304 may include the first rod check valve 316 and a second rod check valve 402, which block fluid flow in both directions. In this way, for example, the rod control valve 318 may be omitted.

[0051] Fig. 5 illustrates another non-limiting example of the hydraulic suspension system 100 according to the present disclosure. The configuration of Fig. 5 is similar to that of Fig. 3, with similar components identified using like reference numerals, except that a roll control valve 500 may be provided instead of the parallel combination of the first orifice 210 and the second orifice 212. In the illustrated non-limiting example, the roll control valve 500 may include a first port 502 in fluid communication with the first head chamber 186 and a second port 504 in fluid communication with the second head chamber 196. The roll control valve 500 may be moveable between a first position where fluid communication is provided between the first head chamber 186 and the second head chamber 196 through an orifice 506, and a second position where fluid communication is provided directly between the first head chamber 186 and the second head chamber 196. In the illustrated non-limiting example, the roll control valve 500 may be proportionally moveable between the first position and the second position. In this way, for example, the roll control valve 500 may act as a variable orifice arranged between the first head chamber 186 and the second head chamber 196.

[0052] The operating characteristics of the hydraulic suspension system of Fig. 3 may be similar to the operating characteristics of the hydraulic suspension system of Fig 1, described above. However, the suspension stiffness of the first hydraulic actuator 104 and the second hydraulic actuator 106 provided by the first head accumulator 222 and the second head accumulator 224, respectively, may be controlled by proportionally moving the first head control valve 302 and the second head control valve 304 between the first position and the second position. In addition, the roll stiffness defined between the first hydraulic actuator 104 and the second hydraulic actuator 106 may be varied by proportionally actuating the roll control valve

- 15 500 between the first position and the second position. In the illustrated non-limiting example, moving the roll control valve 500 from the first position to the second position may decrease the roll stiffness.

[0053] Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0054] Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.

[0055] Various features and advantages of the invention are set forth in the following claims.

Claims

CLAIMS We claim:

1. A hydraulic suspension system, comprising:

a first hydraulic actuator including a first cylinder and a first piston slidably received within the first cylinder, the first cylinder defining a first head chamber and a first rod chamber;

a second hydraulic actuator including a second cylinder and a second piston slidably received within the second cylinder, the second cylinder defining a second head chamber and a second rod chamber;

a first orifice connected between the first head chamber and the second head chamber;

at least one control valve configured to selectively provide fluid communication between the first head chamber and the second head chamber through a second orifice, the second orifice arranged in parallel with the first orifice; and at least one accumulator connected to the first head chamber and the second head chamber.

2. The hydraulic suspension system of claim 1, further comprising a shuttle valve in fluid communication with the first head chamber and the second head chamber.

3. The hydraulic suspension system of claim 2, wherein the shuttle valve is configured to communicate a highest pressure between the first head chamber and the second head chamber to a head relief valve.

4. The hydraulic suspension system of claim 1, further comprising a rod accumulator in fluid communication with the first rod chamber and the second rod chamber.

5. The hydraulic suspension system of claim 1, further comprising a rod accumulator selectively placed in fluid communication with the first rod chamber and the second rod chamber via a rod control valve.

6. The hydraulic suspension system of claim 1, wherein the second orifice is arranged externally from the at least one control valve.

7. The hydraulic suspension system of claim 1, wherein the second orifice is arranged within the at least one control valve.

8. The hydraulic suspension system of claim 1, further comprising a first head accumulator and a second head accumulator.

9. The hydraulic suspension system of claim 8, wherein the at least one control valve comprises a first head control valve arranged between the first head chamber and the first head accumulator and a second head control valve arranged between the second head chamber and the second head accumulator.

10. The hydraulic suspension system of claim 9, wherein at least one of the first head control valve and the second head control valve is an electrohydraulic proportional valve.

11. The hydraulic suspension system of claim 9, wherein at least one of the first head control valve and the second head control valve is an on/off valve.

12. The hydraulic suspension system of claim 9, wherein at least one of the first head control valve and the second head control valve is selectively moveable between a first position where fluid flow is inhibited in one direction therethrough and a second position where fluid communication is provided therethrough.

13. The hydraulic suspension system of claim 9, wherein at least one of the first head control valve and the second head control valve is selectively moveable between a first position where fluid flow is inhibited therethrough and a second position where fluid communication is provided therethrough.

14. The hydraulic suspension system of claim 9, wherein the second orifice is arranged on a connection that extends from between the first head control valve and the first head accumulator to between the second head control valve and the second head accumulator.

15. The hydraulic suspension system of claim 8, wherein the at least one control valve includes a first port, a second port, a third port, and a fourth port and is selectively moveable between a first position, a second position, and a third position, wherein the first port is in fluid communication with the first head chamber, the second port is in fluid communication with the second head chamber, the third port is in fluid communication with the first head accumulator, and the fourth port is in fluid communication with the second head accumulator.

16. The hydraulic suspension system of claim 15, wherein the first position of the at least one control valve provides a first flow path between the first port and the third port and a second flow path between the second port and the fourth port, and wherein the second orifice is connected between the first flow path and the second flow path, wherein the second position of the at least one control valve provides fluid communication between the first port and the third port and the second port and the fourth port, and wherein the third position blocks each of the first port, the second port, the third port, and the fourth port.

17. The hydraulic suspension system of claim 16, wherein the at least one control valve is an electrically operated proportional valve.

18. The hydraulic suspension system of claim 16, wherein the at least one control valve is normally biased to the first position.

19. The hydraulic suspension system of claim 16, wherein the at least one control valve is normally biased to the third position.

20. A hydraulic suspension system, comprising:

at least one control valve configured to selectively vary a restriction along a fluid path defined between the first head chamber and the second head chamber, thereby selectively varying a roll stiffness defined between the first hydraulic actuator and the second hydraulic actuator; and at least one accumulator connected to the first head chamber and the second head chamber.

21. The hydraulic suspension system of claim 20, wherein the at least one control valve is moveable between a first position where fluid communication is provided between the first head chamber and the second head chamber through an orifice and a second position where fluid communication is provided directly between the first head chamber and the second head chamber.

22. The hydraulic suspension system of claim 20, further comprising a first orifice connected between the first head chamber and the second head chamber.

23. The hydraulic suspension system of claim 22, wherein the at least one control valve is configured to selectively vary the restriction along the fluid path by opening an additional fluid path between the first head chamber and the second head chamber that includes a second orifice in parallel with the first orifice.

24. The hydraulic suspension system of claim 23, wherein the second orifice is arranged externally from the at least one control valve.

25. The hydraulic suspension system of claim 23, wherein the second orifice is arranged within the at least one control valve.

26. The hydraulic suspension system of claim 20, further comprising a shuttle valve in fluid communication with the first head chamber and the second head chamber.

27. The hydraulic suspension system of claim 26, wherein the shuttle valve is configured to communicate a highest pressure between the first head chamber and the second head chamber to a head relief valve.

28. The hydraulic suspension system of claim 20, further comprising a rod accumulator in fluid communication with the first rod chamber and the second rod chamber.

29. The hydraulic suspension system of claim 20, further comprising a rod accumulator selectively placed in fluid communication with the first rod chamber and the second rod chamber via a rod control valve.

30. The hydraulic suspension system of claim 20, further comprising a first head accumulator and a second head accumulator.

31. The hydraulic suspension system of claim 30, wherein the at least one control valve comprises a first head control valve arranged between the first head chamber and the first head accumulator and a second head control valve arranged between the second head chamber and the second head accumulator.

32. The hydraulic suspension system of claim 31, wherein at least one of the first head control valve and the second head control valve is an electrohydraulic proportional valve.

33. The hydraulic suspension system of claim 31, wherein at least one of the first head control valve and the second head control valve is an on/off valve.

34. The hydraulic suspension system of claim 31, wherein at least one of the first head control valve and the second head control valve is selectively moveable between a first position where fluid flow is inhibited in one direction therethrough and a second position where fluid communication is provided therethrough.

35. The hydraulic suspension system of claim 31, wherein at least one of the first head control valve and the second head control valve is selectively moveable between a first position where fluid flow is inhibited therethrough and a second position where fluid communication is provided therethrough.

36. The hydraulic suspension system of claim 31, wherein the second orifice is arranged on a connection that extends from between the first head control valve and the first head accumulator to between the second head control valve and the second head accumulator.

37. The hydraulic suspension system of claim 30, wherein the at least one control valve includes a first port, a second port, a third port, and a fourth port and is selectively moveable between a first position, a second position, and a third position, wherein the first port is in fluid communication with the first head chamber, the second port is in fluid communication with the second head chamber, the third port is in fluid communication with the first head accumulator, and the fourth port is in fluid communication with the second head accumulator.

38. The hydraulic suspension system of claim 37, wherein the first position of the at least one control valve provides a first flow path between the first port and the third port and a second flow path between the second port and the fourth port, and wherein the second orifice is connected between the first flow path and the second flow path, wherein the second position of the at least one control valve provides fluid communication between the first port and the third port and the second port and the fourth port, and wherein the third position blocks each of the first port, the second port, the third port, and the fourth port.

39. The hydraulic suspension system of claim 38, wherein the at least one control valve is an electrically operated proportional valve.

40. The hydraulic suspension system of claim 38, wherein the at least one control valve is normally biased to the first position.

41. The hydraulic suspension system of claim 38, wherein the at least one control valve is normally biased to the third position.