Patent Application
20170146034
The present invention relates to a fluid actuator arrangement according to the preamble of claim 1 and to a method for controlling a fluid actuator arrangement according to claim 16. The invention also regards a data medium storing program comprising a program code, which program when run on a computer executes the method according to claim 16. The invention also regards an apparatus arranged to be infinitely movable according to claim 18.
The present invention concerns the industry using hydraulic and pneumatic actuators for different types of applications and concerns the manufacture industry producing such arrangements.
The invention is not limited thereto, but can also be used for replacing electrical actuator arrangements and can be adapted for application of a wide range of different types industries.
There is a desire to provide a fluid actuator arrangement that can distribute control functionality regarding force and motion rate of the piston rod arrangement.
Current technology uses fluid actuator arrangements that are designed with specific features for achieving optimal pressure. This may imply overweight and over-dimension materials, which for a specific operating mode may be regarded as superfluous.
Current technology also often uses a centrally controlled operation of maximum motion rate (speed) and force of the piston rod arrangement by means of controlling the fluid flow and pressure of the fluid supply device. Such centrally controlled feeding of fluid makes the current arrangement ineffective.
There is a desire to eliminate inefficient throttling processes performed by servo valves controlling prior art fluid actuator arrangements. Such throttling involves wasted energy through heat dissipation and high energy costs.
U.S. Pat. No. 4,506,867 discloses a jacking apparatus for effecting motion of loads by means of two double-acting hydraulic cylinders for providing increased force of a power stroke. Hydraulic fluid pressure is controlled to a predetermined flow rate to the hydraulic cylinders for increasing the speed of a repositioning stroke of the apparatus.
U.S. Pat. No. 3,220,317 discloses a servo system having a hydraulic motor system with two pistons arranged in tandem for each motor. The system uses two motors connected in parallel so that their motions are in fixed proportions and their forces are added. The system may also be arranged with the motors in series so that forces are in fixed proportions and motion added.
There is an object to reach more efficient control of speed and force of a fluid actuator arrangement.
Yet another object is to reduce power output of the fluid supply device (pump).
There is also an object to reduce energy losses.
A further object is to develop an energy saving fluid actuator arrangement comprising compact cylinders promoting the benefits of longer piston rod arrangements having longer piston rod path compared with prior art fluid actuator arrangements.
A yet further object is thus to provide a more compact fluid actuator arrangement.
An object is to provide a fluid actuator arrangement exhibiting a lower weight compared with prior art fluid actuator arrangements.
An object is to improve current fluid actuator arrangements in mobile and industrial applications.
An object is to provide fluid actuator arrangements to accomplish work with only a small amount of input force.
A further object is to increase energy efficiency for a fluid actuator arrangement operating under various motion/movement and force performance selected from actual requirement or condition, without need of additional energy consuming throttling valves.
Furthermore, an object is to reduce the size of components and systems of a fluid actuator arrangement, while maintaining or increasing power output.
A further object is to provide a fluid actuator arrangement, which can be used in smart fluid power component systems including self-diagnostics and plug-and-play (easy to use) functionality.
A yet further object is to minimize the environmental impact by lowering noise and eliminating large leaks.
An object is to provide a fluid actuator arrangement that can be used cost-effective in material handling equipment applications. Material handling equipment, such as electronic overhead travelling cranes, level luffing cranes and stackers can thus make use of the present fluid actuator arrangement. Also other types of cranes may make use of the arrangement, such as overhead cranes, mobile cranes, tower cranes, telescopic cranes, loader cranes, which cranes comprise long hydraulic cylinders. Also forklifts, telehandlers and production line conveyors may make use of the present fluid actuator arrangement. The application of the present fluid actuator arrangement covers a major range of industries, such as oil refineries, power and energy facilities, food and beverage industries, retails, container terminals aiming at faster solutions for container logistics offering shorter time for container ships in harbour. Also elevators for buildings may make use of the present fluid actuator arrangement. Also offshore/marine applications, paper and steel industry machinery, pneumatic industry may make use of the present fluid actuator arrangement.
A further object is to provide a fluid actuator arrangement that can be used for the production of agricultural equipment, including tractors, combine harvesters, loaders, hay balers, mulching machines and lawn and garden equipment, such as earth mowers, forest harvesters, etc.
One aspect of the present invention is to adapt the arrangement to 3D-printing in plastic, composite and/or metal applications for aircraft and automotive industry. This promotes high process speed and high accuracy for prototypes (rapid prototyping), demonstration units and small volume production.
A further object is to provide an arrangement that can be used in 3D-printing of entire buildings.
An object is to provide an arrangement that can be used in automated storage and retrieval systems for car parking and rough-terrain robots, so called legged robot systems.
A yet further object is to provide a fluid actuator arrangement that can be used in the construction end-market, including vehicles such as excavators, steam rollers, backhoe loaders, concrete machines, drilling rigs, and wheel loaders used adapted for construction of infrastructure, e.g. roads, bridges, buildings or tunnels.
Furthermore, an object is to provide a fluid actuator arrangement that can be used in the upstream oil and gas industry, primarily at the wellhead and including jacking systems used to raise and lower oil well drilling and service platforms, excavators, off-road dump trucks and rigs.
A further object is to provide a fluid actuator arrangement that can be put into use in light, medium and heavy hydraulic presses used for metal forming, including die casting, forging, extrusion, drawing, pressing machines, mould making, casting, etc.
A yet further object is to provide a fluid actuator arrangement adapted for aerospace vehicles. There is a need for weight saving and less bulky arrangements. The present fluid actuator arrangement can be used in systems for landing gears, engines, ramps, door actuation devices, brakes and wheels, flight controls and fuel systems etc. The arrangement can also be used in ground handling equipment, baggage handling equipment and specialty aircraft repair equipment. The aerospace segment has always been a major consumer of heavy duty hydraulic cylinders and arrangements for saving weight have been developed over long time. The weight saving of commercial aircraft is extremely important today regarding so called “green aviation” as less weight of the aircraft will reduce fuel consumption and thus less NOx and CO2 emissions. One aspect is thus to put the present fluid actuator arrangement in use in both civil and military applications, in manned and unmanned aircrafts, and especially for large civil aircraft.
Additionally, an object is to provide a fluid actuator arrangement that can be used in military equipment utilizing hydraulic and/or pneumatic mechanisms. This includes armoured personnel carriers, aircraft material handlers, cranes and loaders, hook lifts, track adjusters and truck-mounted bridge layers.
Large milling (CNC) machines and hydraulic robots for aircraft, automotive may make use of the fluid actuator arrangement.
An object is to provide an arrangement that can be adapted to mining machines, mine and mountain drilling rigs, etc.
A further object is to provide a fluid actuator arrangement that can be used in mining drills and breakers, crushing, pulverizing and screening equipment, mineral processing machinery, surface mining equipment, underground mining machinery and other mining equipment.
This has been achieved by the arrangement defined in the introduction and being characterized by the features of the characterizing part of claim 1.
Thereby is achieved that the first chamber can be pressurized with a first pressure, wherein the first piston device will be secured to the piston rod arrangement by means of the piston rod engagement and disengagement device actuated by the first pressure. Disengagement of the first piston device from the piston rod arrangement is performed when the first chamber is pressurized with a second pressure or not being pressurized.
Preferably, the second pressure being lower than the first pressure.
Thereby is achieved a fluid actuator arrangement comprising at least one actuator, the definition of which corresponds to a cylinder comprising a piston device and piston rod arrangement, using a releasable piston allowing discrete adjustability of the total cross-section piston force area.
In such way it is possible to provide precise motion control without the need of current inefficient throttling process. There is therefore provided less inefficient throttling for the present arrangement than for prior art arrangements. Current motion control often involves wasted energy through heat dissipation and required heavy and expensive cooling systems.
Preferably, the valve device is adapted to control that the first pressure is higher than the second pressure and alternatively (in case of pneumatic actuator arrangement) the second pressure is reservoir pressure.
It is thus provided a modular fluid actuator arrangement that comprises three main functionalities. Firstly, a hybrid actuator comprising at least one conventional piston constantly in engagement with the piston rod may be used. Secondly, there is a possibility to use two or more cylinders in tandem using one common piston rod and wherein respective piston of each cylinder comprises a piston rod engagement and disengagement device, which is adapted to engage or disengage the piston from the piston rod. Thirdly, a locking arrangement mode is possible, wherein a piston-like clamping device using the fluid supply system or external fluid supply systems (or wherein both chambers of respective cylinder may optionally be pressurized for activating the piston engagement and disengagement device in a locked position) is used. Such application may be advantageous in case of error in operation. Said three function modes can also be combined. Such combinations may regard different force areas of the cross-sections of the pistons.
In such way is achieved that unlimited lengths of piston rods can be used that opens up for various types of industrial areas.
Thereby is achieved a possibility to control the fluid actuator arrangement in an efficient way depending upon the actual need of fluid power for a specific situation.
In such way is achieved a major reduction in power losses, when compared to prior art arrangements. Thereby, no or less throttling losses are present and it is achieved that the fluid actuator arrangements. This implies, e.g. for mobile applications, that significant fuel savings can be made and less CO2 emissions.
According to current technology, a designer must adapt prior art arrangement to match force and speed requirements e.g. to match high force and slow speed or low force and high speed by introducing servo valves. Such servo valves throttle one or several actuators depending upon desired force and rate of motion and acceleration of the piston rod.
By means of the claimed features, the designer will have a unique possibility to adjustment/management of the cylinder area of the arrangement by engaging/disengaging one or several pistons to the piston rod arrangement, thereby optimizing the performance of the actuator arrangement to varying speed and force requirements.
By means of the piston rod engagement and disengagement device, which is adapted to engage the piston device to the piston rod arrangement, there is achieved that a precise motion of the piston rod arrangement can be made in combination with a less energy consuming throttle valve.
In such way is achieved a fluid actuator arrangement that has substantially higher power to weight ratio resulting in higher machine frame resonant frequencies for a given power level and high stiffness of the control system of the present arrangement.
Thereby is provided a fluid actuator arrangement operating in a stiff manner and that achieves high loop gain capability, great accuracy and frequency response.
In such way is achieved a fluid actuator arrangement performing smooth performance at low speed and which have a wide speed range by changing the force area of the present arrangement.
This means that a fluid actuator arrangement is provided that to a great extent is self-cooling and that can be operated in stall condition indefinitely without damage.
In such way is achieved a compact, short and light-weight cylinder having a smaller volume of oil (in case of being a hydraulic actuator) in the first and second chamber of the cylinder than that of conventional hydraulic cylinders. Elongated and heavy prior art cylinders can thus be eliminated. Additional oil volume in bulky reservoir tanks is needed for prior art cylinders. Extraction and extension of prior art actuators requires large oil volume. By means of the claimed features it is provided that less bulky oil reservoir tanks can be used for the arrangement.
Preferably, the first and second cylinder are arranged in tandem and the first and second piston device being associated with a common piston rod of the piston rod arrangement.
In such way there is provided a less bulky arrangement using a common piston rod.
Current control of prior art arrangements for changing working point involves the use of energy consuming throttling valves. Such prior art throttling results in wasted energy through heat dissipation and thus requires heavy and expensive cooling systems. By means of the claimed features a cooling system of the present arrangement can be designed to be less bulky than prior art cooling systems.
Thereby are achieved reductions in weight and volume. This involves smaller components (cylinder, oil reservoir, oil cooler and fuel tank) than prior art and thus more cost-efficient assembly. In such way is achieved an arrangement having less gross weight, requiring less manufacture costs, and having a very compact design.
Suitably, the second piston device comprises a piston rod engagement and disengagement device adapted to be able to engage or disengage the second piston device to/from the piston rod arrangement.
In such way is achieved an optimal and secure functionality providing accurate performance.
Thereby is provided a compact and low-weight (and energy saving) fluid actuator arrangement that can propel a piston rod arrangement a major distance and back again, wherein the respective piston device in turn is engaged with the piston rod arrangement.
Thereby is achieved that both piston devices can be engaged with the piston rod arrangement for generating a larger force area of the piston devices. Such additional force is suitable for achieving that the piston rod arrangement can accelerate a heavy load.
Preferably, the piston device (when not in engagement with the piston rod) is centrally positioned in the cylinder for operating the fluid actuator arrangement in a symmetrically manner in opposite directions.
Optionally, this can be achieved by two spring elements provided at each side of the piston device, seen in a direction corresponding with the elongation of the piston rod arrangement.
Alternatively, this can be achieved by an electromagnetic device.
Suitably, a third cylinder comprising a third piston device is arranged in tandem with the first and second cylinder (preferably using a common piston rod).
Thereby a unique maximal long piston rod can be used for a wide range of applications, e.g. elevators, forklifts, cranes, 3D printing/CNC machines, mine drilling rigs, container terminals, profile rail guides etc. Such use of long piston rods opens up new areas for hydraulic actuators and pneumatic actuators. The length of the piston rod is not dependent on cylinder length. Also an aspect of the invention disclosing only two cylinders may involve such unique maximal long piston rod.
Alternatively, the piston rod engagement and disengagement device additionally being adapted to engage the first piston device to the piston rod arrangement, when the second chamber is pressurized.
In such way there is achieved high flexibility in speed and force. The achieved arrangement can be seen as a hydraulic “gear box”. Heavy loads can be moved at high speed with high acceleration and retardation in combination with very accurate motions at low speed.
Preferably, the piston rod engagement and disengagement device is adapted for stiff/rigid engagement (rigidity in axial direction).
This implies safe operation of the fluid actuator arrangement and optimal precision of motion.
Suitably, the piston device and the piston rod arrangement (piston rod) are free to move relative each other and also relative the cylinder per se encompassing the piston device and a portion of the piston rod.
Alternatively, the piston rod engagement and disengagement device comprises a cavity forming a flexible piston inner wall portion adapted for releasable engagement with the piston rod arrangement.
Preferably, the cavity extends around the longitudinal axis of the piston device parallel with the circumference of the bore hole of the piston device and at a proper distance from the latter so that a suitable mass of material (e.g. same material as the rest of the piston device) constitutes said piston inner wall portion. Said mass of material forming the piston inner wall portion is such flexible that increased pressure in the cavity expands the piston inner wall portion thereby clamping onto the piston rod arrangement.
By means of said flexible piston inner wall adapted for only minor movement in radial direction for clamping (secure) the piston arrangement, the number of motions is high and the arrangement can be classified as a long-life arrangement.
Thereby is achieved that a portion (comprising a section of the piston inner wall) of the material of the piston device can be used for radially clamping said portion of the piston device onto the piston rod arrangement outer surface (envelope surface) by introducing a high pressure in the cavity, thus expanding the portion (i.e. the piston inner wall of the piston device) in direction radially inwardly in engagement with the piston rod arrangement. Vice versa, the piston device is disengaged from the piston rod arrangement when the fluid not being pressurized in the cavity, wherein said portion will retract to its original state and said section of the piston inner wall moves outwardly in a radial direction from the piston rod and disengages the piston device from the envelope surface of the piston rod.
Preferably, the piston rod engagement and disengagement device comprises a membrane device adapted for releasable engagement with the piston rod arrangement.
In such way is achieved a membrane used between the piston rod and the piston device. By applying a pressurized fluid to the membrane by means of a logic valve being in fluid communication with the pressurized fluid in the actual chamber of the cylinder comprising the releasable piston device, the piston device will be connected with maximum secure, fast and reliable clamping to the piston rod arrangement. Such membrane also promotes fast disconnection (disengagement) of the piston device from the piston rod arrangement.
Preferably, the piston rod engagement and disengagement device comprises a clamping device and/or locking member
The speed and force of the piston rod can thus be controlled in an efficient way by varying the active total piston area in discrete steps. Multiple cylinder chambers with releasable pistons can be combined in several ways in order to find the most suitable speed-and-force solution for a specific application.
Suitably, the piston rod engagement and disengagement device comprises a pressure strengthening device, which is provided to strengthening the engagement of the first piston device to the piston rod arrangement.
In such way is achieved that the piston device is rigidly secured to the piston rod arrangement and which can be performed a short time period.
Preferably, the pressure strengthening device is arranged within the piston device and comprises a movable micro piston rod having a first micro pressure area and a second micro pressure area. The first micro area being larger than the second micro pressure area, and is in fluid communication with the pressurized (main) fluid. The second micro pressure area may be arranged in communication with a separate high pressure fluid provided in a cavity (for membrane functionality) of the piston device forming the cavity of the piston rod engagement and disengagement device.
Suitably, the arrangement comprises a hydraulic actuator arrangement.
Thereby is achieved that a secondary control is provided. Such secondary control is one of the most efficient control methods for hydraulic systems. Such secondary control of the present hydraulic actuator arrangement also presents low hydraulic capacitance, which additionally saves power.
In such way is achieved energy saving and reduced power demand of the primary hydraulic supply device (such as a power unit). In such way fuel consumption and operative costs being reduced. There is also achieved that cooling capacity will comply with current emission regulations.
According to one aspect of the present invention, so called secondary control of hydraulic cylinders can be realized by utilizing a multi-chamber cylinder approach with releasable (possible to disconnect/disengage) pistons. The principle of such a secondary control is to control the torque of the hydraulic motor by controlling the displacement of the motor. By means of this aspect, a variable displacement unit can be provided for a hydraulic cylinder, but also in this case the present arrangement with variable cross-sectional force area.
By means of the claimed features, the need for prior art emission reduction technology is reduced. Such prior art emission reduction technology usually is complicated, expensive and difficult to integrate into machine application and apparatuses to be used. Furthermore, by means of the claimed features is achieved that energy waste through heat dissipation is decreased and lighter, smaller and less expensive cooling systems can be used. The impact on the environment is thus less vulnerable and the present fluid actuator arrangement can be regarded as “Green” technology.
In such way is provided a high stiffness and high natural frequency (compared with prior art actuator arrangements) due to less volume used in the present cylinder chamber (compared to conventional cylinders). These factors are favourable in control design.
Preferably, a first cross-sectional force area of the first piston device differs from a second cross-sectional force area of the second piston device.
There is thus possible to control the fluid actuator arrangement performance by altering the fluid actuator arrangement's effective force area during operation. This introduces a new level of energy efficiency to hydraulic/pneumatic systems used in current power transmissions.
Suitably, the arrangement comprises a first actuator provided with a first force area, a second actuator provided with a second force area corresponding with the first force area, a third actuator provided with a third force area, a fourth actuator provided with a fourth force area, the third force area is twice as large as the first force area, the fourth force area is twice as large as the third force area.
In such way is achieved that a fast piston motion can be achieved with minor piston force. The respective force area is defined as the cross-sectional area of the respective piston device. For reaching such fast piston motion and minor force, the first force area (e.g. 1 area unit) is activated by alternating engagement of the first and second actuator to the piston rod arrangement. For achievement of an alternative performance of the arrangement, for example a slow piston motion with high force, all activators are activated. The high force may be achieved by activating all four force areas (e.g. 8 area units=1+1+2+4, i.e. the respective force area of the first, second, third, fourth actuator). This implies an optimal combination of eight different force area units, which can be selected from required piston motion rate and force of piston device. Prior art actuators can be built for 8 area units and being determined for slow piston motion with high force. However, such prior art actuator will, when used for fast motion and minor force, require that the entire cylinder volume must be pressurized and a part of the pressurized fluid (fed from the fluid supply device) must be throttled for decreasing the force. Prior art arrangements thus will generate energy losses.
Preferably, also other force area combinations are possible. For example 1+1+1+1+1+1 or 1+2+4+8+16+32 or 1+1+2+4+8+16+32 or others.
Alternatively, the arrangement comprises a plurality of actuators.
By controlling the total cross-sectional force area of the arrangement, the motion rate and the force of the piston rod can be changed and optimized in an efficient way. The actual needs of operation for a certain situation can be satisfied by changing said total cross-sectional force area of the arrangement. This is due by the formula V=Q/A and the formula F=P*A, wherein “V” is the motion rate of the piston device, “Q” is the fluid flow, “A” is the area of the piston device, “F” is the force of the piston device and “P” is the pressure of the fluid. For example, by decreasing the area “A” (e.g. by disengaging one piston), the motion rate “V” is increased at the same time as the force “F” is decreased.
In such way is achieved that a modular actuator arrangement can be assembled from desired provisions regarding force and speed of the piston rod arrangement—for example high force and slow speed or low force and high speed and furthermore desired distance for piston rod arrangement motion, braking action, precision adjustment of the piston rod arrangement to a predetermined accurate position etc. Such modular actuator arrangement can operate with less throttling compared with prior art. According to one aspect of the present invention there is provided that engagement and disengagement of piston devices to/from the piston rod arrangement will imply flexibility and less energy losses compared with prior art.
Preferably, the arrangement comprises an electro-hydraulic cylinder apparatus.
In such way is achieved accuracy, enhanced functionality, improved ease-of-use and controlled performance. Electro-hydraulic cylinders incorporate servo valves and electronic controls such as transducers to provide rod position feedback and to ensure efficient machine operations. This enables sophisticated control of speed and position of loads in several applications of the arrangement according to this aspect.
The arrangement is suitable adapted for an aircraft comprising the arrangement according to any of claims 1-13.
Suitably, the aircraft is a commercial aircraft designed for long distance flights.
The arrangement is preferably adapted for any of the following industrial segments; construction industry, jacking systems for oil well drilling and service platforms, agricultural equipment industry, marine industry, crane manufacture industry, paper and steel industry, rough-terrain robot manufacture industry or others.
Alternatively, the arrangement comprises a pneumatic actuator arrangement.
Preferably, a fluid actuator arrangement is provided that can distribute control functionality regarding force and motion rate of the piston rod arrangement providing infinite piston (and/or cylinder arrangement) transfer motion compared with prior art fluid actuator arrangements.
Suitably, first chamber is pressurized with a first pressure, wherein the first piston will be in engagement with the piston rod by means of said first pressure transferred directly to and acting upon the piston rod engagement and disengagement device via a channel system having an opening entering the first cylinder chamber and having another opening entering a cavity of a membrane.
The piston rod engagement and disengagement device is thus directly controlled by the first pressure of the pressurized first chamber, wherein said first pressure also acts onto a flexible member (membrane) of the piston rod engagement and disengagement device of the piston device, which flexible member thereby expands in radial direction towards the piston envelope surface and clamps around the piston rod.
Preferably, the piston rod engagement and disengagement device is rigidly fixed to the piston of the piston device and the first pressure of the pressurized first chamber acting onto the piston for moving the piston device in axial direction will thus also simultaneously act on the membrane of the piston rod engagement and disengagement device for actuating the piston rod engagement and disengagement device to engage it with the piston rod, thus also moving the piston rod relative the cylinder arrangement. The piston rod engagement and disengagement device will thus upon pressurizing of the first chamber be engaged with the piston rod by means of the first pressure pressing the flexible member (membrane) in radial direction towards the piston rod envelope surface.
There is thus achieved that an engagement between the piston rod and piston device is performed directly and promptly without any additional mechanical parts and can be controlled by the same control device (control valve device and control unit) which controls the movement of the piston device relative the cylinder arrangement by the pressurization of the respective cylinder chamber.
Suitably, the second piston device comprises a piston rod engagement and disengagement device adapted to be able to engage or disengage the second piston device to/from the piston rod arrangement in a similar way as described for the first piston device.
In such way is achieved an optimal and secure functionality providing accurate performance of the fluid actuator arrangement.
Thereby is provided a compact and low-weight (and energy saving) fluid actuator arrangement that can propel a piston rod arrangement a major distance and back again, wherein the respective piston device in turn is engaged with the piston rod arrangement.
In such way is achieved a membrane that can be used as a coupling device between the piston rod and the piston device.
By arranging the piston device for directly feeding the pressurized fluid from the pressurized cylinder chamber to the membrane, the piston device will be connected with maximum secure, fast and reliable clamping to the piston rod arrangement. Such directly controlled membrane also promotes fast disconnection (disengagement) of the piston device from the piston rod arrangement. Said feeding is preferably provided via a channel system of the piston device from the pressurized cylinder chamber to the membrane. By the use of a logic valve provided for controlling the flow of fluid to the respective cylinder chamber, that logic valve will thus also control the piston rod engagement and disengagement device.
The speed and force of the piston rod and/or cylinder arrangement can thus be controlled in an efficient way by varying the active total piston area in discrete steps. Multiple cylinder chambers with releasable pistons can be combined in several ways in order to find the most suitable speed-and-force solution for a specific application.
Suitably, a control unit is arranged to control the control valve (controlling the direction of motion of the piston rod) and to control a respective logic valve coupled to the respective cylinder arrangement.
The control valve is preferably arranged for directing the hydraulic flow to the cylinder chambers of the respective cylinders. It is thereby possibly to control the actuating of the piston rod engagement and disengagement device of the first piston of the first cylinder independently from controlling the piston rod engagement and disengagement device of the second piston of the second cylinder.
Suitably, the fluid supply device is provided for feeding fluid to the respective cylinder separately and/or in combination via the control valve and respective logic valve.
Preferably, each logic valve is coupled via lines/hoses (or other fluid communication devices) to the respective cylinder and to the control valve.
Each logic valve is coupled to both cylinder chambers of the respective cylinder.
Preferably, the control unit controls the valve device for pressurizing a cylinder chamber of the first cylinder, wherein is achieved instantaneously that the piston rod engagement and disengagement device of the piston device of the first cylinder is pressurized for providing engagement between the common piston rod and the piston device.
Suitably, the control unit is provided for controlling the valve device (e.g. the control valves) for providing a second pressure (lower than the first pressure) to the second cylinder so that the piston rod engagement and disengagement device is not in engagement (i.e. disengaged or released from the piston rod) with the common piston rod.
Preferably, said features disclosed in the both previous paragraphs are combined.
Suitably, the respective piston rod engagement and disengagement device of the first and second piston device comprises at least a cavity, which being formed within the piston device. The cavity is provided for fluid communication with the respective cylinder chamber of the respective cylinder via at least a channel system.
Preferably, the channel system comprises a non-return valve or a shuttle valve or other valve that hinders the pressurized fluid in the first cylinder chamber to reach the second cylinder chamber of the cylinder and vice versa.
In such way is achieved that no fluid communication can be performed between the first and second cylinder chamber. When the first cylinder chamber is pressurized, the cavity of the piston rod engagement and disengagement device is pressurized without any effect that the pressurized fluid flows to the second cylinder chamber. The pressurization of the cavity will instantaneously expand the piston inner wall portion (flexible member), thereby directly providing a radial clamping force upon the piston rod. The cavity is positioned in the piston so that it is coaxial with and parallel with the piston inner wall portion and at a distance from the piston rod envelope surface (i.e. coaxial with the piston rod).
Suitable, the mass of material forming the piston inner wall portion exhibits a flexible material property for providing that the pressurized cavity will expand the mass of material of the inner wall portion in a radial direction (inwardly) towards the piston rod for engagement of the piston device to the piston rod.
Preferably, the channel system of the piston device comprises an inlet opening facing the cylinder chamber and an opening facing the cavity of the piston rod engagement and disengagement device, so that the cavity of piston rod engagement and disengagement device directly can be pressurized when the cylinder chamber is pressurized.
Suitably, the cavity (or cavities) extends (extend) around the longitudinal axis of the piston device and parallel and coaxially with the piston rod at a predetermined distance. The cavity (or cavities) thus extends (extend) in the direction corresponding with the cylinder axis and being formed coaxially with the X-axis of the piston device corresponding with the X-axis of the piston rod.
Preferably, when pressurizing the cavity, the radial clamping force acting on the piston rod during engagement will alter linearly with the pressurizing.
Suitably, when pressurizing, the mass of material forming the piston inner wall portion will expand uniformly towards the piston rod and provide a rigid coupling between the piston and the piston rod.
Preferably, upon depressurization, the mass of material forming the piston inner wall portion of the first piston device will revert to its original measure wherein the first piston device can slide freely along the common piston rod to be positioned to a starting position in the first cylinder ready for repeated pressurizing of the cylinder chamber and anew engaging and moving the piston rod relative the cylinder arrangement a yet further distance.
Suitably, shortly before the first cylinder is depressurized permitting the piston device to slide freely to a new position, the second cylinder is pressurized and the mass of material forming the piston inner wall portion of the second piston expands uniformly towards the piston rod and provide a rigid coupling (engagement) between the second piston device and the piston rod.
Alternatively, as soon as the second piston device is engaged with the piston rod, the first cylinder is depressurized.
Suitably, when pressurizing, the mass of material forming the piston inner wall portion and forming the membrane expands radially and engages with the piston rod in such way that the membrane is able to transfer axial forces from the piston device to the piston rod.
Preferably, each piston device (first and second or any suitable number) of a respective cylinder arrangement comprises a membrane being designed as an inner sleeve open at its ends.
The inner sleeve is preferably surrounded by an outer housing coaxially arranged around the inner sleeve and encompassing the inner sleeve.
Suitably, a cavity or a plurality of cavities being formed between an outer surface of the inner sleeve and an inner surface of the surrounding outer housing.
Alternatively, the outer housing comprises a fluid channel comprising a first opening entering the cavity and a second opening entering the outer envelope surface of the outer housing for fluid communication with the cylinder chamber via a passage provided in the piston.
Suitably, the inner sleeve is made flexible and comprises e.g. bronze-based material or other suitable materials.
Preferably, the end of the housing is covered by a support ring and the opposite end comprises a shoulder protruding inwardly for fixation of the inner sleeve to (within) the outer housing.
Alternatively, both opposite ends seen in the longitudinal direction of the housing is covered by a respective support ring for fixation of the inner sleeve to (within) the outer housing.
Preferably, seals (O-rings) are arranged in end positions of the membrane between the outer surface of the inner sleeve and the inner surface of the outer housing for providing a seal between the inner sleeve and the outer housing.
Suitably, the membrane (comprising the outer housing, inner sleeve and support ring) is mounted in the piston with a suitable bias.
Preferably, the inner surface (facing the piston rod envelope surface) of the inner sleeve is provided with a helical groove or grooves for achieving smooth operation of the piston and uniform friction between the inner sleeve and the piston rod envelope surface for effective sliding of the piston along the piston rod when the piston is disengaged from the piston rod. Such helical groove or grooves will also provide rigid engagement of the piston to the piston rod when the membrane is pressurized for engagement.
In such way is achieved a compact design and assembly of the membrane.
By means of the pressurization of the first cylinder chamber there is also achieved that the cavity automatically is pressurized for engagement of the piston device to the piston rod. This is achieved by that the pressurized fluid will enter the channel system of the piston and the passage of the outer housing and further to the cavity, thereby pressing the flexible inner sleeve in radial direction towards the piston rod for engagement. The pressurization of the cavity will instantaneously expand the inner sleeve.
By the arrangement providing the direct fluid communication between the cylinder chamber and the cavity, there is thus provided quick engagement and disengagement of the piston rod engagement and disengagement device to/from the piston rod.
There is thus provided accurate positioning of the piston to the piston rod for engagement.
There is thus achieved that eventual radial run-out is eliminated by the use of the flexible membrane.
There is in such way avoided that any running off with offset set centre of the membrane relative the piston rod will occur.
By such accurate positioning is achieved that the engagement between the piston rod and the inner surface of the piston device (membrane) will not damage the contact surfaces between the piston rod envelope surface and the piston (membrane).
Suitably, the open ends of the housing is covered by a respective support ring.
Thereby is achieved that the membrane is easy to dismount.
Preferably, the pressurized fluid is controlled to flow from the supply fluid device to respective cylinder chamber via control valves and/or logic valves.
Suitably, the pressurizing of the cavity for engagement of the piston device to the piston rod is made by direct feeding of the pressurized fluid from the cylinder chamber to the cavity.
Preferably, the pressurizing of the membrane is made via a channel system of the piston device, which channel system is provided for fluid communication between the respective cylinder chamber and the cavity of the membrane.
Suitably, the channel system has an inlet opening at the piston force area of the piston device, facing the cylinder chamber, so that the pressurized fluid is permitted to enter directly to the cavity of the membrane via the channel system.
Thereby is achieved that the pressurization of the cavity for controlling the piston rod engagement and disengagement device can be performed by controlling the control valves and/or logic valves coupled to the fluid supply.
There is thus not needed any additional fluid system or additional fluid controlled mechanical arrangement for providing an engagement of the piston device to the piston rod.
Thereby is achieved an extremely quick pressurization and/or depressurization of the cavity of the membrane.
Suitably, the piston rod engagement and disengagement device of the piston device is provided with a plurality of membranes.
Preferably, the plurality of membranes being coupled via a channel system to the respective cylinder chamber for fluid communication for pressurizing the cavities of the membranes for engaging the membrane to the piston rod.
Suitable, the cylinders are rigidly coupled to each other in axial direction forming a common cylinder arrangement along the longitudinal axis.
This is also achieved by a method for controlling a fluid actuator arrangement according to claim 16.
Preferably, the method further comprises the step of providing the second pressure to all cylinder chambers of the fluid actuator arrangement to disengage all the piston rod engagement and disengagement devices.
This is also achieved by an apparatus arranged to be infinitely movable, the apparatus includes a fluid actuator arrangement of claim 18.
This is also achieved by a data medium storing program (P) for moving an apparatus according to claim 19 and a data medium storing program product according to claim 20.
Suitably, a first and second non-return valve being arranged within the piston device and coupled to the channel system.
Preferably, the first non-return valve permits the fluid from the first cylinder chamber to enter the cavity via the common channel system and/or vice versa.
Each non-return valve will thus allow the fluid of the respective pressurized cylinder chamber to flow through the common channel to the membrane cavity providing actuating of the piston rod engagement and disengagement device without the feeding of fluid from one chamber to the other.
Suitable, at least two piston devices each comprises a channel system only provided between a first cylinder chamber and a cavity of the piston rod engagement and disengagement device for providing direct fluid communication between the cavity and the first cylinder chamber. There is in this embodiment not provided any channel between the second cylinder chamber and the cavity.
Thereby is achieved a simplified arrangement suitable to put into use in apparatuses propelled with a force just in one direction (e.g. elevators).
This is a cost effective arrangement since there is even not needed any shuttle valve.
Preferably, a return pressure is applied to a cylinder chamber for returning the piston device to a starting point. The return pressure being lower than the first pressure for not activating the piston rod engagement and disengagement device.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description, taken in conjunction with the appended claims and the accompanying drawings.
The present invention will now be described by way of examples with references to the accompanying schematic drawings, of which:
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein for the sake of clarity and understanding of the invention some details of no importance may be deleted from the drawings.
In
In
In
Each cylinder 104′, 104″, 104′″ defines a cylinder space 205 in which the respective piston device 111′, 111″, 111′″ is slidingly provided. The respective piston device 111′, 111″, 111′″ is slidingly provided along the cylinder axis X and around the common piston rod 109 arranged along the cylinder axis X. The respective piston device 111′, 111″, 111′″ sealingly divides the cylinder space 205 into a first 115 and second 117 cylinder chamber. Each cylinder chamber 115, 117 comprises a fluid channel 210 provided in the cylinder sleeve 201 for permitting pressurized fluid to flow in or out to/from the respective cylinder chamber 115, 117.
The respective piston rod engagement and disengagement device 137′, 137″, 137′″ being controlled by the pressurized fluid of the actual cylinder chamber 115, 117. Alternately pressurizing of the respective cylinder chamber 115, 117 of the first cylinder 104′ with a fluid pressure P will imply that the fluid pressure P, via a first channel system 165′ of the first piston device 111′, also directly and momentary will pressurize a first cavity 139′ of the piston rod engagement and disengagement device 137′ formed in the first piston device 111′. Upon such pressurization of the cavity 139′, an expandable membrane (an inner wall portion 163′ of the first piston device 111′ will expand and press tightly (clamp) against the piston rod 109 with an inwardly directed radial force. Thus, by pressurizing the cylinder chamber 115 of the first cylinder 104′, the first piston device 111′ will directly engage the piston rod 109 by means of the piston rod engagement and disengagement device 137′ utilizing the same pressure P being applied to the first cylinder chamber 115 of the first cylinder 104′. As the first cylinder chamber 115 of the first cylinder 104′ being pressurized, the expandable membrane (first inner wall portion 163′) will expand and engage the piston device 111′ to the piston rod 109. The engagement of the first piston device 111′ to the piston rod 109 outer envelope surface 206 plus the pressurized first cylinder chamber 114, implies that the first piston device 111′ will propel the piston rod 109 a cylinder stroke length as part of an infinite and continuous motion of the piston rod.
A control unit 133 controls the valve device 121 comprising a first 125′, a second 125″ and a third 125′″ logic valve and a control valve 123 to pressurize respective cylinder chamber and at the same time the belonging piston engagement and disengagement device 137′, 137″, 137′″. In
According to one aspect the method comprises the step of providing the second pressure to all cylinder chambers 15, 17 of the fluid actuator arrangement 1 to disengage all the piston rod engagement and disengagement devices 137′, 137″, 137′″ for performing a disengagement of all piston devices 111′, 111″, 111′″, so that the arrangement 1 momentary disengage all piston devices 111′, 111″, 111′″ from the piston rod 109 in case the piston rod 109 propels a large mass using the kinetic energy of the mass (in a way reminding of a freewheel clutch).
Alternatively, a locking mode is possible, wherein a piston-like clamping device using the fluid supply system or external fluid supply systems (or wherein both chambers of respective cylinder may optionally be pressurized for activating the piston engagement and disengagement device in a locked position) is used. Such application may be advantageous in case of error in operation.
The passage 211 may have a shuttle valve 209 arranged to obstruct the fluid fed to the first cylinder chamber 115 from entering the second cylinder chamber 117. The shuttle valve 209 is tube-formed comprising three openings and a ball or other blocking valve element that moves freely within the tube (or other valve member). The shuttle valve 209 prevents the fluid from travelling from one cylinder chamber to the other, but allows the fluid to flow through a middle opening coupled to the channel system 165′. The first cylinder chamber 115 is pressurized with a pressure P for moving the piston 111′ in the direction of arrow A. The fluid fed into the first cylinder chamber 115 also enters the first channel system 165′ via the passage 211 and the shuttle valve 209 and further to the first cavity 139′. The first cavity 139′ of the piston rod engagement and disengagement device 137′ is formed by an inner side of a piston inner wall portion 163′ (i.e. outer side of the inner sleeve 198) and the inner side of the outer housing 199. The cavity (or cavities) thus extends parallel with and in a direction circumferentially around the envelope surface of the piston rod 109 and in an direction along the cylinder axis X (the cavity or cavities being e.g. cylindrical shaped and coaxially arranged within the piston rod engagement and disengagement device 137′). The mass of material forming the inner sleeve 198 adjacent the first cavity 139′ is so flexible that the increased pressure in the first cavity 139′ will expand the mass of material of the inner wall portion 163′. The piston inner wall portion 163′ is expanded by means of the pressure P and being pressed in radial direction (with a force F) towards the piston rod 109 envelope surface for engagement with the piston rod 109. By means of the pressurization of the first cylinder chamber 115 there is thus also achieved that the first cavity 139′ per se is pressurized. This is achieved by that the pressurized fluid will enter also the passage 211 of the first piston 111′ and the channel system 165′ and further to the first cavity 139′. The pressurization of the first cavity 139′ will instantaneously expand the piston inner wall portion 163′ for providing engagement between the piston device 111′ and the piston rod 109 for moving the piston rod 109.
A computer program (which can be of any type suitable for any operational data) is stored in the first memory unit 930 for controlling the functionality of the CPU device 900.
Furthermore, the CPU device 900 comprises a bus controller (not shown), a serial communication port (not shown) providing a physical interface, through which information transfers separately in two directions. The device 900 also comprises any suitable type of I/O module (not shown) providing input/output signal transfer, an A/D converter (not shown) for converting continuously varying signals from detectors (not shown) of the production line and other monitoring units (not shown) of the production line into binary code suitable for the computer.
The CPU device 900 also comprises an input/output unit (not shown) for adaption to time and date. The CPU device 900 also comprises an event counter (not shown) for counting the number of event multiples that occur from independent events in operation. Furthermore, the CPU device 900 includes interrupt units (not shown) associated with the computer for providing a multi-tasking performance and real time computing in said production line. The NVM 920 also includes a second memory unit 940 for external controlled operation.
A data medium storing program P comprising routines adapted for controlling the control valves and provided for operating the CPU device 900 for performing the present method described herein. The data medium storing program P comprises routines for providing smooth motion of the fluid actuator arrangement in an automatic or semi-automatic way. The data medium storing program P comprises a program code stored on a medium, which is readable on the computer, for causing the control unit 200 to perform the operation of the fluid actuator arrangement by controlling the fluid actuator arrangement comprising a first and second piston rod engagement and disengagement device of a respective first and second piston device in moving a piston rod a first distance by controlling a valve device to pressurize a first cylinder chamber of the first cylinder and, via a channel system, simultaneously pressurize a first cavity for expanding a flexible piston inner wall portion providing a radial clamping force onto the piston rod; moving the piston rod a second distance, and by controlling the valve device to pressurize a first cylinder chamber of a second cylinder and, via a second channel system of the second cylinder, simultaneously pressurize a second cavity for expanding a flexible piston inner wall portion providing a radial clamping force onto the piston rod and simultaneously (or shortly afterwards) controlling the valve device to disengage the piston rod engagement and disengagement device of the first cylinder from the piston rod by pressurizing the first cylinder chamber of the first cylinder with a second pressure being lower than the first pressure; and repeating the steps for moving the piston rod further distance.
The data medium storing program P further may be stored in a separate memory 960 and/or in a read/write memory 950. The data medium storing program P is in this embodiment stored in executable or compressed data format.
It is to be understood that when the processing unit 910 is described to execute a specific function that involves that the processing unit 910 executes a certain part of the program stored in the separate memory 960 or a certain part of the program stored in the read/write memory 950.
The processing unit 910 is associated with a data port 999 for communication via a first data bus 915. The non-volatile memory NVM 920 is adapted for communication with the processing unit 910 via a second data bus 912. The separate memory 960 is adapted for communication with the processing unit 910 via a third data bus 911. The read/write memory 950 is adapted to communicate with the processing unit 910 via a fourth data bus 914. The data port 999 is preferably connectable to data links of the fluid actuator arrangement.
When data is received by the data port 999, the data will be stored temporary in the second memory unit 940. After that the received data is temporary stored, the processing unit 910 will be ready to execute the program code, according to the above-mentioned procedure. Preferably, the signals (received by the data port 999) comprise information about operational status of the fluid actuator arrangement, such as operational status regarding the position of the piston rod relative the cylinder arrangement. It could also be operational data regarding the speed and brake performance of the fluid actuator arrangement. According to one aspect, signals received by the data port 999 may contain information about actual positions of the apparatus 400 in
Parts of the method can also be executed by the device 900 by means of the processing unit 910, which processing unit 910 runs the data medium storing program P being stored in the separate memory 960 or the read/write memory 950. When the device 900 runs the data medium storing program P, suitable method steps disclosed herein will be executed. A data medium storing program product comprising a program code stored on a medium is also provided, which product is readable on a suitable computer, for performing the method steps according to any of claims 16 to 17, when the data medium storing program P according to claim 19 is run on the control unit 133.
The arrangement may according to different aspects be adapted to one or several of following industrial segments; construction industry, jacking systems for oil well drilling and service platforms, agricultural equipment industry, marine industry, crane manufacture industry. The arrangement is not limited to be used in such segments, but also other industrial segments are possible.
The present invention is of course not in any way restricted to the preferred embodiments described above, but many possibilities to modifications, or combinations of the described embodiments, thereof should be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention as defined in the appended claims. One aspect involves that the arrangement can be adapted for momentary disengaging all pistons from the piston rod in case the piston rod propels a large mass using the kinetic energy of the mass (in a way reminding of a freewheel clutch). The valve device may comprise a logic valve of suitable type. The valve member may comprise a 5 ports/2 valve positions, so called 5/2 valve or others. The valve member may comprise a two-way valve of any type suitable for the arrangement. The manoeuvring of the valve member may be performed by means of a solenoid connected to a control unit adapted for controlling the valve member and thereby the arrangement. The arrangement may be adapted for fast and high clamp force engagement of the piston device for propelling the latter accurate also for acceleration of heavy loads. By manoeuvring the valve member, such as a logical valve, the same arrangement can perform also lower force and slow motion rate of the piston rod arrangement. A logical valve can be manoeuvred by the control unit to shut down the fluid flow to excluded cylinder/cylinders and only direct fluid flow to only one cylinder. There are different types of valves that can be used for providing the above-mentioned aspects and other aspects. Electro-hydraulic controlled valves, other types of directly controlled electro-hydraulic logical valves, etc. The arrangement can be used in civil and military, manned and unmanned aircraft: Leading/Trailing Edge Flap Actuators; Landing Gear Actuators; Air Brakes; Primary Servo Actuators (PSA); Electro-Hydrical Actuator (EHA) applications etc.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/SE2014/050753 | Jun 2014 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2015/050684 | 6/12/2015 | WO | 00 |
