GB2603949A - Method for controlling height of work machines - Google Patents

Method for controlling height of work machines Download PDF

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Publication number
GB2603949A
GB2603949A GB2102466.6A GB202102466A GB2603949A GB 2603949 A GB2603949 A GB 2603949A GB 202102466 A GB202102466 A GB 202102466A GB 2603949 A GB2603949 A GB 2603949A
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GB
United Kingdom
Prior art keywords
fluid
accumulator
pressure
control valve
end chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB2102466.6A
Other versions
GB202102466D0 (en
Inventor
P Nieuwsma Derek
James Argenziano Nicholas
S Doy Nathaniel
W Muir Jason
S Frantz Matthew-D
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar Paving Products Inc
Original Assignee
Caterpillar Paving Products Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Caterpillar Paving Products Inc filed Critical Caterpillar Paving Products Inc
Priority to GB2102466.6A priority Critical patent/GB2603949A/en
Publication of GB202102466D0 publication Critical patent/GB202102466D0/en
Publication of GB2603949A publication Critical patent/GB2603949A/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/015—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements
    • B60G17/016—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input
    • B60G17/0165—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load the regulating means comprising electric or electronic elements characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input to an external condition, e.g. rough road surface, side wind
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/06—Servomotor systems without provision for follow-up action; Circuits therefor involving features specific to the use of a compressible medium, e.g. air, steam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
    • B60G17/04—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics
    • B60G17/0416—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics regulated by varying the resiliency of hydropneumatic suspensions
    • B60G17/0424—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics regulated by varying the resiliency of hydropneumatic suspensions by varying the air pressure of the accumulator
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
    • B60G17/04—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics
    • B60G17/056—Regulating distributors or valves for hydropneumatic systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G17/00—Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load
    • B60G17/02—Spring characteristics, e.g. mechanical springs and mechanical adjusting means
    • B60G17/04—Spring characteristics, e.g. mechanical springs and mechanical adjusting means fluid spring characteristics
    • B60G17/056—Regulating distributors or valves for hydropneumatic systems
    • B60G17/0565—Height adjusting valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2300/00—Indexing codes relating to the type of vehicle
    • B60G2300/02—Trucks; Load vehicles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2300/00—Indexing codes relating to the type of vehicle
    • B60G2300/02—Trucks; Load vehicles
    • B60G2300/026—Heavy duty trucks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2300/00—Indexing codes relating to the type of vehicle
    • B60G2300/09—Construction vehicles, e.g. graders, excavators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2400/00—Indexing codes relating to detected, measured or calculated conditions or factors
    • B60G2400/60—Load
    • B60G2400/61—Load distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2500/00—Indexing codes relating to the regulated action or device
    • B60G2500/20—Spring action or springs
    • B60G2500/206—Variable pressure accumulators for hydropneumatic suspensions
    • B60G2500/2062—Variable pressure accumulators for hydropneumatic suspensions by varying the air-pressure of the accumulator
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2800/00—Indexing codes relating to the type of movement or to the condition of the vehicle and to the end result to be achieved by the control action
    • B60G2800/90—System Controller type
    • B60G2800/91—Suspension Control
    • B60G2800/915—Suspension load distribution
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Vehicle Body Suspensions (AREA)

Abstract

A method for controlling a height of a work machine (100, Figure 1) is provided. The method includes:- i) determining an expansion or retraction event of a fluid cylinder 122; ii) moving a valve 210 to a first condition in response to the expansion or retraction event to disallow fluid communication between an accumulator 212 and an end chamber 170, 172 of the fluid cylinder 122; iii) receiving a pressure signal associated with a fluid pressure at the end chamber 170, 172 upon completion of the expansion or retraction event to cause a proportional pressure control valve 218 to move and equalize a fluid pressure of the accumulator 212 with the fluid pressure at the end chamber 170, 172 of the fluid cylinder 122; and iv) moving the valve 210 to a second condition pursuant to an equalization of the fluid pressure of the accumulator 212 with the fluid pressure at the end chamber 170, 172 of the fluid cylinder 122 to allow the fluid communication between the accumulator 212 and the end chamber 170, 172 of the fluid cylinder 122.

Description

METHOD FOR CONTROLLING HEIGHT OF WORK MACHINES
Technical Field
[0001] The present disclosure relates to a method for controlling a height of a milling machine. More particularly, the present disclosure relates to a method for controlling fluid pressure in an accumulator of a hydraulic system that is applied to lift or lower a frame of the milling machine.
Background
[0002] Machines, such as milling machines, e.g., road reclaimer machines, stabilizer machines, cold-planer machines, etc., may be used to cut, mix, and pulverize a ground surface. A milling machine typically includes fl uid cylinders (or legs) that may be fluidly powered to extend or retract to lift or lower a frame of the machine relative to the ground surface. These fluid cylinders may be powered by a hydraulic system that may use pressurized fluid to extend or retract the fluid cylinders.
[0003] To provide a cushioning or dampening effect to the movement of the fluid cylinders, and/or to provide an improved ride performance, such hydraulic systems may include accumulators. Accumulators may be in fluid communication with end chambers of the fluid cylinders to receive pressurized fluid from the end chambers and/or direct pressurized fluid to the end chambers. Fluid pressure of such accumulators is typically set at a fixed value or the accumulators may be filled with oil during the initial raising or lowering event of the fluid cylinders and may possess a fluid pressure that may be different from fluid pressure of the end chambers However, in case of varying ground conditions and/or machine configurations (e.g., slope or pitch of the machine), setting the fluid pressure of the accumulators to a fixed value may cause the fluid cylinders to extend or retract (in case the fixed value is either relatively higher or lower than fluid pressure of the end chambers) once the accumulators are fluidly connected to their corresponding fluid cylinders.
[0004] U.S. Patent No. 6,398,227 discloses a method for adjusting a ride of a loader vehicle. The method includes providing an adjustable accumulator assembly having a pressure operatively connected to hydraulic load holding, circuit, and a controller operatively connected to the accumulator assembly. Further, the method includes determining a load on the hydraulic load holding circuit and adjusting the number of gas molecules in the adjustable accumulator assembly to a level which is optimum for the load.
Summary of the Invention
[0005] In an aspect the present disclosure is directed to a method for controlling a height of a work machine. The method includes determining, by a controller, an expansion or retraction event of a fluid cylinder to lift or lower a frame of the work machine with respect to one or more traction devices of the work machine. The method further includes moving, by the controller, a valve to a first condition in response to the expansion or retraction event to disallow fluid communication between an accumulator and an end chamber of the fluid cylinder. Also, the method includes receiving, by a proportional pressure control valve, a pressure signal associated with a fluid pressure at the end chamber of the fluid cylinder upon completion of the expansion or retraction event to cause the proportional pressure control valve to move and equalize a fluid pressure of the accumulator with the fluid pressure at the end chamber of the fluid cylinder. Furthermore, the method includes moving, by the controller, the valve to a second condition pursuant to an equalization of the fluid pressure of the accumulator with the fluid pressure at the end chamber of the fluid cylinder to allow the fluid communication between the accumulator and the end chamber of the fluid cylinder.
Brief Description of Drawings
[0006] FIG. 1 is a side-view of an exemplary work machine having a frame and one or more traction devices, in accordance with an embodiment of the present disclosure; [0007] FIG. 2 is a schematic diagram of a hydraulic system for controlling a height of the work machine, in accordance with an embodiment of the present disclosure; [0008] FIG. 3 is a schematic diagram of a hydraulic system for controlling a height of the work machine, in accordance with another embodiment of the present disclosure; and [0009] FIG. 4 is a flowchart illustrating an exemplary method for controlling the height of the work machine, in accordance with an embodiment of the present disclosure.
Detailed Description
[0010] Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
[0011] Referring to FIG. 1, an exemplary work machine 100 is illustrated.
The work machine 100 may operate at a worksite 102. The worksite 102 may include a road construction site, a mine site, a landfill, a quarry, and the like. The work machine 100 may engage with a work surface 104 of the worksite 102 and alter geographical features of the work surface 104. In the embodiment illustrated in FIG. 1, the work machine 100 is a road reclairner machine 100' configured to pulverize asphalt present on the work surface 104 and mix it with the underlying base to stabilize the work surface 104. However, in various other embodiments, the work machine 100 may embody or represent other machines that may alter the geography of the worksite 102 or the work surface 104 by performing one of a milling operation, a grading operation, a leveling operation, or a material removal operation, within the worksite 102.
[0012] The work machine 100 may include a forward end 106 and a rearward end 108 opposite to the forward end 106. The forward end 106 and the rearward end 108 may be defined in relation to an exemplary direction of travel (indicated by an arrow:A1 of the work machine 100, with said direction of travel being defined from the rearward end 108 towards the forward end 106. Further, the work machine 100 includes a frame 112, one or more traction devices 114, a propulsion system 116, an operator cabin 118, a milling assembly 120, and one or more fluid cylinders 122. The frame 112 may extend from the forward end 106 towards the rearward end 108 of the work machine 100. The frame 112 may accommodate the propulsion system 116, the operator cabin 118, the milling assembly 120, and the fluid cylinders 122, although other known components and structures may be supported by the frame 112, as well.
[0013] The frame 112 may be supported on the work surface 104 by the traction devices 114. In the illustrated embodiment, the traction devices 114 include a pair of front wheels 130 (only one wheel shown) disposed adjacent to the forward end 106 and a pair of rear wheels 132 (only one wheel shown) disposed at the rearward end 108 of the work machine 100. One or more of the pair of front wheels 130 and the pair of rear wheels 132 may be configured to be powered by the propulsion system 116 to propel the work machine 100 on the work surface 104 in a desired direction and at a desired speed, according to a customary practice known in the art. In some embodiments, the traction devices 114 may include crawler tracks (not shown) provided either alone or in combination with the wheels 130, 132.
[0014] The propulsion system 116 may include an engine (not shown), such as an internal combustion engine, configured to power operations of various systems on the work machine 100, typically by combusting fuel. Optionally, the propulsion system 116 may also include an electrical power source, applicable either alone or in combination with the internal combustion engine.
[0015] The operator cabin 118 may be supported over the frame 112. The operator cabin 118 may facilitate stationing of one or more operators therein, to monitor the operations of the work machine 100. Also, the operator cabin 118 may house various components and controls of the work machine 100, access to one or more of which may help the operators to control the work machines movement and/or operation. For example, the operator cabin 118 may include an input device 140 that may be used and/or actuated to generate an input for facilitating control of various systems associated with the work machine 100 (e.g., to control movement of the fluid cylinders 122). The input device 140 may include, but not limited to, one or more of joysticks, touch screens, switches, and the like. In the illustrated embodiment the operator cabin 118 is located proximal to the forward end 106 of the work machine 100 and distal to the rearward end 108 of the work machine 100. In some embodiments, the work machine 100 may be operated autonomously or semi-autonomously. In such a case, the operator cabin 118 may be omitted from the work machine 100 and various input devices, such as the input device 140, may be located remotely from the work machine 100.
[0016] The milling assembly 120 may be coupled to a bottom side 142 of the frame 112. The milling assembly 120 may include a mixing chamber 150 and a rotor 152 disposed within the mixing chamber 150. The rotor 152 may include a plurality of cutting elements 154 arranged around its periphery to grind and/or pulverize the work surface 104. In the illustrated embodiment, the mixing chamber 150 and the rotor 152 are disposed between the pair of front wheels 130 and the pair of rear wheels 132. However, in some embodiments, it may be contemplated that the mixing chamber 150 and the rotor 152 may be disposed at an alternative location, such as at one of the forward end 106 and the rearward end 108, of the work machine 100.
[0017] Continuing with FIG. 1, the frame 112 may be moveably coupled to the traction devices 114, via the fluid cylinders 122 (each fluid cylinder being referred by the reference numeral 122). Each fluid cylinder 122 is configured to extend and retract to lift or lower the frame 112 with respect to the traction devices 114, for example, to attain a desired height above the work surface 104. Each fluid cylinder 122 may include a cylinder portion 164 and a rod portion 166 (see FIGS. 2 and 3). The cylinder portion 164 may be fixedly coupled to the frame 112. The rod portion 166 may be operatively coupled to the cylinder portion 164 such that the rod portion 166 may be displaceable with respect to the cylinder portion 164. The rod portion 166 may be coupled to a piston 168 accommodated within the cylinder portion 164 at one end and may be coupled to the traction device 114 at the other end. The piston 168 may divide the cylinder portion 164 into a head end chamber 170 and a rod end chamber 172. Both the head end chamber 170 and the rod end chamber 172 may be configured to receive fluid for displacing the rod portion 166 (or piston 168) with respect to the cylinder portion 164. In an embodiment, the rod end chamber 172 may receive fluid to retract the fluid cylinder 122 to lower the frame 112 with respect to the traction device 114, and the head end chamber 170 may receive fluid to extend the fluid cylinder 122 to lift the frame 112 with respect to the traction device 114.
[0018] Referring to FIG. 2, a hydraulic system 200 is shown. The hydraulic system 200 is configured to control the movement (e.g., expansion or retraction) of one of the fluid cylinders 122. The hydraulic system 200 includes a head end conduit 202, a rod end conduit 204, a tank 206, a fluid source 208, a flow control valve 210, an accumulator 212, an accumulator outlet conduit 214, a valve 216, a proportional pressure control valve 218, a pressure control conduit 220, a first control valve 222, a second control valve 224, a tank conduit 226, a pump conduit 228, a first pressure sensor 230, a second pressure sensor 232, and a controller 240. However, it may be contemplated that, in some embodiments, the hydraulic system 200 may include additional or different components, such as, for example, pressure relief or makeup valves, pressure compensating elements, restrictive orifices, counterbalance valves, and other hydraulic components, known in the art.
[0019] The head end conduit 202 may extend from the head end chamber 170 of the fluid cylinder 122 to the valve 216 and to the flow control valve 210. The rod end conduit 204 may extend from the rod end chamber 172 to the flow control valve 210. The tank 206 may be configured to store fluid. The fluid source 208 may be fluidly coupled with the tank 206 to pump fluid from the tank 206. The fluid source 208 may be a hydraulic pump (e.g., a variable or a fixed displacement pump) configured to draw fluid from the tank 206 and provide a pressurized fluid to the fluid cylinder 122 and to the accumulator 212.
[0020] The flow control valve 210 may be fluidly coupled to the head end chamber 170 of the fluid cylinder 122, via the head end conduit 202. Also, the flow control valve 210 may be fluidly coupled to the rod end chamber 172 of the fluid cylinder 121 via the rod end conduit 204. The flow control valve 210 may be a directional valve configured to move between a first state, a second state, and a closed state. For instance, in the first state, the flow control valve 210 may direct fluid from the fluid source 208 to the rod end chanter 172, via the rod end conduit 204, and may cause the head end chanter 170 to release the fluid, via the head end conduit 202, to the tank 206 to retract the fluid cylinder 122. In the second state, the flow control valve 210 may direct fluid from the fluid source 208 to the head end chamber 170, via the head end conduit 202, and may cause the rod end chanter 172 to release the fluid, via rod end conduit 204, to the tank 206 to extend the fluid cylinder 122. In the closed state, the flow control valve 210 may restrict the flow of fluid to the fluid cylinder 122.
[0021] Additionally, i n the illustrated embodi ment, a counterbalance valve 242 may be connected to the head end conduit 202. The counterbalance valve 242 may be responsive to a fluid pressure of the rod end chamber 172 to control a movement of the fluid cylinder 122. The counterbalance valve 242 may allow free flow of fluid towards the head end chamber 170 and is piloted open when the rod end chamber 172 is commanded flow. In a steady state condition, the counterbalance valve 242 may act as a relief valve to prevent over pressurization of the head end chamber 170.
[0022] The accumulator 212 may include a reservoir to store pressurized fluid that may be received from and/or be supplied to, for example, the fluid cylinder 122, as required. For that purpose, the accumulator 212 may be selectively fluidly connected to the fluid cylinder 122, via the valve 216. In the present embodiment, the valve 216 may fluidly connect the head end conduit 202, associated with the head end chamber 170 of the fluid cylinder 122, with the accumulator outlet conduit 214 of the accumulator 212. T he valve 216 may be a solenoid-controlled valve configured to move between a first condition (to disallow fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122) and a second condition (to allow fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122).
[0023] The proportional pressure control valve 218 is fluidly connected to the accumulator 212 (or the accumulator outlet conduit 214), via the pressure control conduit 220. Also, the proportional pressure control valve 218 may selectively connect the accumulator to the fluid source 208 and/or to the tank 206 through the accumulator outlet conduit 214, to help the accumulator 212 attain a fluid pressure, as desired. In the present embodiment, the proportional pressure control valve 218 is a three-way two-position valve. However, any other known proportional pressure control mechanism known in the art may be used.
[0024] In the present embodiment, the pump conduit 228 is connected to the proportional pressure control valve 218 via the first control valve 222, whereas the tank conduit 226 is connected to the proportional pressure control valve 218 via the second control valve 224. The first control valve 222 may include a two-way poppet type bidirectional valve configured to move between a normally closed position and an open position (when actuated). For example, in the normally closed position, the first control valve 222 may block the flow of fluid in both directions, i.e., from the fluid source 208 to the accumulator 212, and vice versa, whereas in the open position, the first control valve 222 may allow the flow of fluid in both directions, i.e., from the fluid source 208 to the accumulator 21/ and vice versa. Similarly, the second control valve 224 may include a two-way poppet type bidirectional valve configured to move between a normally open position and a closed position (when actuated). For example, in the normally open position, the second control valve 224 may allow the flow of fluid in both directions, i.e., from the accumulator 212 to the tank 206, and vice versa, whereas in the closed position, the second control valve 224 may block the flow of fluid in both directions, i.e., from the accumulator 212 to the tank 206, and vice versa.
[0025] The first pressure sensor 230 is connected to an end chamber (i.e., either to the head end chamber 170 or to the rod end chamber 172) of the fluid cylinder 122. In the present embodiment, the first pressure sensor 230 is connected to the head end conduit 202 coupled to the head end chamber 170 of the fluid cylinder 122. The first pressure sensor 230 may be configured to generate a signal indicative of a fluid pressure at the end chamber (or the head end chamber 170) of the fluid cylinder 122. Similarly, the second pressure sensor 232 is connected to the accumulator 212 (or accumulator outlet conduit 214, as shown in FIG. 2). The second pressure sensor 232 may be configured to generate a signal indicative of a fluid pressure of the accumulator 212 (or a fluid pressure at the accumulator outlet conduit 214).
[0026] The controller 240 may be communicably coupled (e.g., wirelessly) to the input device 140. The controller 240 may be able to detect an actuation of the input device 140 and receive the input from the input device 140. Based on such actuation and the receipt of the input, the controller 240 may be configured to determine an expansion or retraction event of the fluid cylinder 122.
[0027] With regard to the hydraulic system 200, as disclosed in FIG. 2, the controller 240 may be communicably coupled to the first pressure sensor 230, the second pressure sensor 232, the valve 216, the proportional pressure control valve 218, the first control valve 222, and the second control valve 224. In response to the expansion or retraction event, the controller 240 may be configured to move the valve 216 to the first condition. In the first condition, the valve 216 is configured to disallow fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122.
[0028] Further, the controller 240 may be configured to receive signals indicative of the fluid pressure of the head end chamber 170 of the fluid cylinder 122 (from the first pressure sensor 230) and signals indicative of the fluid pressure of the accumulator 212 (from the second pressure sensor 232). Based on the signals received, the controller 240 may be configured to process the signals received from the first pressure sensor 230 and the second pressure sensor 232 to generate a pressure signal. Based on the pressure signal, the controller 240 may control the proportional pressure control valve 218 to move and equalize the fluid pressure of the accumulator 212 with the fluid pressure at the head end chamber 170 of the fluid cylinder 122. At this point, the controller 240 may be configured to move the first control valve 222 and the second control valve 224 to the open positions to allow the proportional pressure control valve 218 to regulate the fluid pressure of the accumulator 212, for example, by increasing the fluid pressure received from the fluid source 208 or by decreasing the fluid pressure by draining some portion of the fluid to the tank 206.
[0029] Once the fluid pressure of the accumulator 212 is equalized with the fluid pressure of the head end chamber 170 of the fluid cylinder 122, the controller 240 may be configured to move the first control valve 222 and the second control valve 224 to the closed positions to block the flow of fluid between the accumulator 212, the fluid source 208, and the tank 206. Pursuant to an equalization of the fluid pressure of the accumulator 212 with the fluid pressure of the head end chanter 170 of the fluid cylinder 122, the controller 240 may be configured to move the valve 216 to the second condition. In the second condition, the valve 216 is configured to allow the fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122.
(0030) Referring to FIG. 3, a hydraulic system 200' is shown. The hydraulic system 200' is similar in many respects to the hydraulic system 200 but differs from the hydraulic system 200 in that the first pressure sensor 230 and the second pressure sensor 232 are omitted. Further, the hydraulic system 200' includes a pilot pressure line 250. The pilot pressure line 250 is fluidly coupled to the head end conduit 202 and is configured to provide a pressure signal (corresponding to the fluid pressure of the head end chanter 170 of the fluid cylinder 122) to the proportional pressure control valve 218. Based on the pressure signal, the proportional pressure control valve 218 may move and equalize the fluid pressure of the accumulator 212 with the fluid pressure at the head end chamber 170 of the fluid cylinder 122. All remaining elements of the hydraulic system 200' may be the same or similar to corresponding elements of the hydraulic system 200 and may be denoted by the same reference numerals as previously used for simplicity.
[0031] With regard to the hydraulic system 200', as disclosed in FIG. 3, the controller 240 may be communicably coupled to input device 140, the valve 216, the first control valve 222, and the second control valve 224. In response to the expansion or retraction event (e.g., determined due to actuation of the input device 140), the controller 240 may be configured to move the valve 216 to the first condition to disallow fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122. In addition, the controller 240 may be configured to move the first control valve 222 and the second control valve 224 to the open positions to allow the proportional pressure control valve 218 to regulate the fluid pressure of the accumulator 212, for example, by increasing the fluid pressure received from the fluid source 208 or by decreasing the fluid pressure by draining some portion of the fluid to the tank 206 Pursuant to the movement of the valve 216 to the first position, movement of the first control valve 222 and the second control valve 224 to the open positions, and movement of the proportional pressure control valve 218 to equalize the fluid pressure of the accumulator 212 with the fluid pressure at the head end chamber 170 of the fluid cylinder 122, the controller 240 may be configured to move the valve 216 to the second condition to allow the fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122. Further, once the fluid pressure of the accumulator 212 is equalized with the fluid pressure of the head end chanter 170 of the fluid cylinder 122, the controller 240 may be configured to move the first control valve 222 and the second control valve 224 to the closed positions to block the flow of fluid between the accumulator 212 and the fluid source 208 and the tank 206.
[0032] The controller 240 may include a processor (not shown) to process the signals received from the first pressure sensor 230 and the second pressure sensor 232. Examples of the processor may include, but are not limited to, an X86 processor, a Reduced Instruction Set Computing (RISC) processor, an Application Specifi c Integrated Circuit (A SIC) procecsor, a Complex Instruction Set Computing (C IS C) processor, an A dvanced RISC Machine (ARM) processor, or any other processor. F urther, the controller 240 may include a transceiver (not shown) configured to enable the controller 240 to communicate (e.g., wirelessly) with the first pressure sensor 230, the second pressure sensor 232, the valve 216, the proportional pressure control valve 218, the first control valve 222, and the second control valve 224, over one or more of wireless radio links, infrared communication links, short wavelength Ultra-high frequency radio waves, short-range high frequency waves, or the like. Example transceivers may include, but not limited to, wireless personal area network (WPAN) radios compliant with various IE E E 802.15 ( B I uetoothir) standards, wireless local area network (W LA N) radios compliant with any of the various IEEE 802.11 (WiFiir) standards, wireless wide area network (WWA N) radios for cellular phone communication, wireless metropolitan area network (W M A N) radios compliant with various IEEE 802.15 (Wi MAX) standards, and wired local area network (LA N) Ethernet transceivers for network data communication. Furthermore, the controller 240 may include a memory (not shown) for accomplishing a task consistent with the present disclosure. The memory may be configured to store data and/or routines that may assist the controller 240 to perform its functions. Examples of the memory may include a hard disk drive (HDD), and a secure digital (SD) card. Further, the memory may include non-volati I e/vol ati le memory units such as a random-access memory (RAM) / a read only memory (ROM), which include associated input and output buses.
[0033] Although it is shown in the illustrated embodiment of FIG. 2 that the hydraulic system 200 is configured to control the movement of one of the fluid cylinders 122, it may be appreciated that similar corresponding hydraulic systems may be applied to control the movement (e.g., expansion or retraction) of the other fluid cylinders 122 of the work machine 100. Similarly, although it is shown in the illustrated embodiment of FIG. 3 that the hydraulic system 200' is configured to control the movement of one of the fluid cylinders 12/ it may be appreciated that similar corresponding hydraulic systems may be applied to control the movement (e.g., expansion or retraction) of the other fluid cylinders 122 of the work machine 100. Further, even though only one accumulator 212 is shown and described in embodiment of FIGS. 2 and 3, it may be appreciated that more than one accumulator could be used and connected to the fluid cylinder 122.
Industrial Applicability
[0034] Referring to FIG. 4, an exemplary method for controlling the height of the work machine 100 is discussed. The method is discussed by way of a flowchart 400, as provided in FIG. 4, that illustrates exemplary stages (i.e., from 402 to 408) accociated with the method. The method is also discussed in conjunction with FIGS. 1,1 and 3.
[0035] During operation, either at the start of a work cycle, or during a work cycle, or at the end of a work cycle, an operator of the work machine 100 may desire to move (i.e., lift or lower) the frame 112 with respect to the traction devices 114 or the work surface 104. In this regard, the operator may manipulate/actuate the input device 140 to expand or retract the fluid cylinder 122. In response to the manipulation/actuation of the input device 140, the controller 240 determines the expansion or retraction event of the fluid cylinder 122 to lift or lower the frame 112 with respect to the traction devices 114 (stage 402 of the flowchart 400).
[0036] Once the expansion or retraction event of the fluid cylinder 122 is determined, the controller 240 may move the valve 216 to the first condition to fluidly disconnect the accumulator 212 (or the accumulator outlet conduit 214) from the head end conduit 202 associated with the head end chamber 170 of the fluid cylinder 122 (stage 404 of the flowchart 400). In that manner, the controller 240 may disallow fluid communication between the accumulator 212 and the head end chamber 170 of the fluid cylinder 122. Subsequent to stage 404, the controller 240 may determine a completion of stage 402, i.e., completion of the expansion or retraction event of the fluid cylinder 122. For example, the controller 240 may determine the completion of said expansion or retraction event by detecting if the actuation of the input device 140 is stopped.
[0037] Upon completion of the expansion or retraction event of the fluid cylinder 122, the controller 240 may receive a signal indicative of the fluid pressure at the head end chamber 170 of the fluid cylinder 122, via the first pressure sensor 230, and a signal indicative of the fluid pressure of the accumulator 212 (or fluid pressure at the accumulator outlet conduit 214), via the second pressure sensor 232. Pursuant to the reception of said signals from the first pressure sensor 230 and the second precsure sensor 232, the controller 240 may compare both signals to determine the pressure difference between the fluid pressure of the accumulator 212 and the fluid pressure at the head end chamber 170, generate a pressure signal corresponding to the pressure difference between the fluid pressure of the accumulator 212 and the fluid pressure at the head end chamber 170, and transmit said pressure signal to the proportional pressure control valve 218.
[0038] According to the embodiment of the hydraulic system 200', as disclosed in FIG. 3, such a pressure signal may be a fluid pressure (of the head end chamber 170 of the fluid cylinder 122) provided to the proportional pressure control valve 218 via the pilot pressure line 250 (connecting the proportional pressure control valve 218 with the head end chamber 170 of the fluid cylinder 122).
[0039] The proportional pressure control valve 218 may receive said pressure signal (stage 406 of the flowchart 400). Upon receiving said pressure signal, the proportional pressure control valve 218 may move (or be proportionally actuated) to equalize the fluid pressure of the accumulator 212 (or the accumulator outlet conduit 214) with the fluid pressure at the head end chamber 170 of the fluid cylinder 122. At this point, the controller 240 may move the first control valve 222 and the second control valve 224 to the open positions to allow the proportional pressure control valve 218 to regulate the fluid pressure of the accumulator 212, for example, by increasing the fluid pressure received from the fluid source 208 or by decreasing the fluid pressure by draining some portion of the fluid to the tank 206. According to the embodiment of the hydraulic system 200, as disclosed in FIG. 2, the controller 240 may provide the pressure signal to the proportional pressure control valve 218 until the fluid pressure of the accumulator 212 is equalized or matched with the fluid pressure at the head end chamber 170 of the fluid cylinder 122. According to the embodiment of the hydraulic system 200', as disclosed in FIG. 3, the controller 240 may receive data related to equalization of the fluid pressure of the accumulator 212 with the fluid pressure at the head end chamber 170 of the fluid cylinder 122, from a separate source (e.g., a control module of the work machine 100), to detect if the fluid pressure of the accumulator 212 is equalized or matched with the fluid pressure at the head end chamber 170 of the fluid cylinder 122.
[0040] Once the fluid pressure of the accumulator 212 is equalized with the fluid pressure of the head end chamber 170 of the fluid cylinder 122, the controller 240 may move the first control valve 222 and the second control valve 224 to the closed positions to block the flow of fluid between the accumulator 212 and the fluid source 208 and the tank 206. Pursuant to the equalization of the fluid pressure of the accumulator 212 (or the accumulator outlet conduit 214) with the fluid pressure at the head end chamber 170, the controller 240 may move the valve 216 to the second condition to fluidly connect the accumulator 212 (or the accumulator outlet conduit 214) with the head end conduit 202 to allow fluid communication between the accumulator 212 and the head end chamber 170 (stage 408 of the flowchart 400).
[0041] Accordingly, the fluid pressure of the accumulator 212 and the fluid pressure at the head end chanter 170 of the fluid cylinder 122 may be equalized and a load match therebetween may be achieved. In this way, the hydraulic system 200, 200' may restrict any bleeding of fluid from the accumulator 212 to the fluid cylinder 122, and vice versa, had there been any pressure difference between the accumulator 212 and the head end chamber 170. As a result, the hydraulic system 200, 200' may prevent the fluid cylinders 122 from retracting or expanding when the accumulators 212 are connected with their corresponding fluid cylinders 122, thus more accurately and efficiently stabilizing machine stationing and/or movement over the work surface 104.
[0042] It will be apparent to those skilled in the art that various modifications and variations can be made to the method/process of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method/process disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.

Claims (1)

  1. Claims What is claimed is: 1. A method for controlling a height of a work machine, the method comprising: determining, by a controller, an expansion or retraction event of a fluid cylinder to lift or lower a frame of the work machine with respect to one or more traction devices of the work machine; moving, by the controller, a valve to a first condition in response to the expansion or retraction event to disallow fluid communication between an accumulator and an end chamber of the fluid cylinder; receiving, by a proportional pressure control valve, a pressure signal associated with a fluid pressure at the end chanter of the fluid cylinder upon completion of the expansion or retraction event to cause the proportional pressure control valve to move and equalize a fluid pressure of the accumulator with the fluid pressure at the end chamber of the fluid cylinder; and moving, by the controller, the valve to a second condition pursuant to an equalization of the fluid pressure of the accumulator with the fluid pressure at the end chamber of the fluid cylinder to allow the fluid communication between the accumulator and the end chamber of the fluid cylinder.
GB2102466.6A 2021-02-22 2021-02-22 Method for controlling height of work machines Withdrawn GB2603949A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1480209A (en) * 1974-07-03 1977-07-20 Data Loop Ltd Digital computers
DE3638574A1 (en) * 1986-11-12 1988-05-26 Rexroth Mannesmann Gmbh Arrangement for controlling the pressure of a damping cylinder for the suspension of vehicles
US5348338A (en) * 1991-06-25 1994-09-20 Honda Giken Kogyo Kabushiki Kaisha Active vehicle suspension system
US6398227B1 (en) * 2000-10-13 2002-06-04 Case Corp. Ride control apparatus and method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1480209A (en) * 1974-07-03 1977-07-20 Data Loop Ltd Digital computers
DE3638574A1 (en) * 1986-11-12 1988-05-26 Rexroth Mannesmann Gmbh Arrangement for controlling the pressure of a damping cylinder for the suspension of vehicles
US5348338A (en) * 1991-06-25 1994-09-20 Honda Giken Kogyo Kabushiki Kaisha Active vehicle suspension system
US6398227B1 (en) * 2000-10-13 2002-06-04 Case Corp. Ride control apparatus and method

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