DE2253451A1 - DRIVE MECHANISM ACTUATED BY A FLOW MEDIUM - Google Patents

Description

Fluid Operated Drive Mechanism The present The invention relates to a drive mechanism actuated by a flow medium and in particular to such a drive mechanism with -selectively adjustable slow or fast operating mode.

The drive mechanism according to the invention actuated by a fluid medium is particularly useful as a hydraulic press, and the present invention refers to an embodiment of the invention as a press, but this one particular use case is not intended in any way to compromise the usability and the Limit the scope of the present invention. In pressing technology, it is useful to to have both fast and slow modes of operation, such as in plastic molding technology, since the greater part of the time of the press movement is only for the opening and closing the mold is used, which is a low Requires strength, but often involves a considerable amount of movement for the shape brings. Since the pressing force required for the actual molding process is in In most cases it is quite high, the hydraulic cylinder and piston need be large, and this requires a transfer of a large volume of the flow medium, to bring about the necessary press movement in most known pressing devices, which have a piston and cylinder unit connected to a flow medium source and is connected to a control system, which only the flow medium in the Cylinder pushes or withdraws the flow medium from the cylinder.

A consequence of the requirement of large volumes of the flow medium is a large capacity equipment that has large fluid pumps, valves and includes lines to achieve a reasonable speed of operation.

Attempts to create improved devices of this type have not led to devices or facilities that would have been able to work with the desired to work fast and slow modes in both directions without simultaneously ' requiring a complex facility. An example of one in the past An attempt made in this direction is disclosed in U.S. Patent 3,418,693.

This patent discloses a piston and cylinder unit with several chambers, with which a fast mode of operation only in one direction different cylinder chamber volumes is achieved, and rapid movement in the opposite direction by a separate and independently operable Cylinder and piston assembly is obtained.

In accordance with the present invention, a fluid medium actuated Drive mechanism created, the at least two cylinder and piston units each having a different volume, with selectively actuatable in the piston Valve devices are provided to achieve the desired fast and slow modes of operation in both Directions to achieve. The need for an independent additional cylinder and Piston unit is switched off by the fact that the cylinder with different Volumes are oppositely aligned and that a fluid connection exists between them to accommodate a relatively small clean flow. The main animal flow of the flow medium takes place internally between the two Chambers of each cylinder by the valve means provided in the piston instead, A high pressing force is achieved by closing the, piston valves, and the resulting slow movement is not essential at the stage of pressing Factor. The reduction in the flow of the flow medium in the outside of the The fluid circuit running through the cylinder and piston units reduces the requirements for the components of the circuit, such as the fluid pump, the valves and cables, with the resulting economic advantages. Operational Advantages are in addition to the optionally adjustable fast and slow Operating modes in both directions an increased efficiency, a reduction the heating of the flow medium and simplified actuation devices.

These and other objects and advantages of the present invention go in an understandable form from the following detailed description of an exemplary embodiment of the present invention in conjunction with the accompanying drawings. In the drawings, Figure 1 is a schematic representation of a flow medium actuated drive device 'embodying the present invention, wherein the Cylinder and piston units are shown schematically in a press, figure 2 is a cross-sectional view of one of the cylinder and piston assemblies along the line 2-2 in Figure 1 and Figure 3 is a partial sectional view through the piston along the Line 3-3 in Figure 2.

In Figure 1, four piston and cylinder units are lo, 11, 12 and 13 shown with two relative to each other movable press plates 14,15 are assembled to form a fluid actuated press. One of the press plates, e.g. plate 14, is arranged rigidly, the (not shapes between the panels in any known and conventional manner could be arranged and supported. Since the present invention is based on the cylinder and piston units and the associated fluid circuit is directed the particular application of the present invention from the schematic representation the press plates 14 and 15 clearly visible.

In this illustrated embodiment, the piston and cylinder units are 1o - 13 arranged in a horizontal line, and it can be seen that they preferably arranged in a square pattern for a symmetrical force distribution would be. The straight-line arrangement of the piston and cylinder units shown results also a symmetrical force distribution and also enables a clearer one Illustration of the invention. While a device with four piston and cylinder units # is inclined, it follows from the following description that only two aggregates 10 and 11 or 12 and 13 are required for an effective embodiment of the invention are if one assumes that asymmetrical forces that occur during a mode of operation be developed with quick movement and little force, of lesser importance are.

Each piston and cylinder assembly 10-13 comprises a fluid cylinder 16 and a piston 17 with a bucket extending to both sides of the piston rod, the extends out of each end of the cylinder in question. The designated 18 Ends of the piston rods of each unit have the same diameter and run through a fluid seal and bushing 19 in the moving plate 15, to which each cylinder 16 is attached or attached. The end parts of the rod ends 18 are rigidly attached to the rigid plate 14 by, for example, shoulder and nut assemblies 18a attached, the piston rods also forming the pulling parts of the press. the opposite ends of piston rods 20 and 21 pass through fluid seals and bushings 24 in the opposite # ends of the respective cylinders 16. In this case Embodiment, the piston rods 20 have the same diameter, which is larger, than the diameter of the opposite piston rods 16, while the piston rods 21 have the same diameter, which is, however, smaller than the diameter of the piston rods 18. Each cylinder 16 is therefore in two chambers 25 and 26 in the case of the units lo and 13 and 27 and 28 in the case of the units 11 'and 12, the maximum Volumes of the chambers in each cylinder are different in relation to one another are. A component 29 rigidly connects the piston rods 20 and 21 of each unit with each other and is supported on the press structure by a vertical support for the piston rods to form.

The pistons 17 are of the same design, and the enlarged sectional views Figures 2 / and 3 can be used to describe each piston with which The only difference is that the piston rods 21 of the units 11 and 12 are smaller Have diameter than the piston rod 20 of the units lo and 13.

So a preferred design are the piston rods 18D 20 and 18, 21 each produced as a unitary part, the piston 17 on the Rod through interlocking threads 32 is attached. Several Piston rings 30 are arranged in corresponding grooves 31 which extend around the piston and provide the necessary fluid seal between the cylinder chambers. Four up and down valves 33 are arranged in each piston, with a fluid channel 34 in the axial direction from the chamber 25 and 27 through the piston body to one Valve seat 35 runs, which cooperates with the surface 36 of the up and down valve. This channel 34 is in effective communication with the chamber 26 or 28 the opposite side of the piston by a configuration of the piston to Formation of the recesses 37, which lead to an opening space 38 in the area of the valves 33 are expanded. So when the valves 33 are moved out of their respective seats 35 free flow can take place between the chambers.

Each poppet valve 33 is axially in its respective one Cylinder 39 slidable, whereby the cylinder is screwed into the piston Cap nut is closed. A compression spring 41 between the cap nut 40 and the valve body 33 and their ends in corresponding recesses 42 and 43 are seated, the valve 33 normally biases in a closed position before, but the valve 33 can by the force of pressurized fluid, which can be exercised by either of the two chambers, can be moved from its seat. A shoulder 44 formed on the valve enables the valve 33 to also is moved by flow medium from the chamber 26 or 28 from its seat. According to a mode of operation of the device according to the invention, it is necessary that on and to hold outgoing valves 33 in the closed position, and this is thereby achieved that pressurized flow medium is passed into the cylinder 39.

The flow medium can expediently to and from the valve cylinder 39 or the cylinder chambers 25, 26, 27 or 28 through passages 45, 46 and 47 are guided in the axial direction by the piston rods 2o or 21, with suitable connections at the outer ends of the respective Piston rods are provided for connection to the fluid circuit. Of the Passage 45 is in communication with a distributor ring 48 in the piston body, and passage extensions 49 extend from the distributor ring to the respective one Valve cylinder 39. The passage 46 'is directly connected to the associated cylinder chamber 26 or 28 at a point near the piston 17 in communication during the passage 47 is in communication with a distributor ring So formed in the piston body and from this via a passage 51 formed in the piston body to the associated cylinder chamber 25 or 27 is in communication. Fluid seals 52, which are arranged in corresponding grooves, maintain fluid separation upright between the cylinder chambers and the cylinders of the poppet valves. Plug 53 and 54 can be used to make drilled holes required for manufacture To seal holes. The flow of the flow medium can through the passages be effected with a relatively small diameter, since the volume of these Passages transferred flow medium is relatively small, and thereby is also the usual external connection between the cylinder walls by flexible Lines or hoses avoided.

Pressurized fluid for actuating the illustrated The invention is embodied in a closed fluid system supplied which a servo-controlled pump 55 with variable displacement and having reversible flow driven by an electric motor 56. the Pump 55 -is provided with openings 57 and 58, which are connected to the lines of the closed Fluid system are connected and depending on the operation of the pump serve as inlet or outlet openings. The electric Control circuit for the motor 56 is not shown, as the necessary circuits would be familiar to those skilled in the art are also known, such as the control of the pump operation. A fluid circuit the one arrangement of four shut-off valves 59 with a pressure relief valve 60 includes, is connected in parallel to the pump ports 57 and 58 to the desired To enable proper functioning of the closed system.

The pressure relief valve So limits the maximum system pressure, the one on a particular valve for a particular embodiment of the invention can be achieved. An additional pump also driven by the electric motor 56 61 with its own pressure relief valve 62 is with this shut-off valve circuit connected to ensure that a minimum system pressure is maintained at all times will operate the pump 55 regardless of its particular mode of operation in any particular Protect instant. The compensation for changes in the required volume of the flow medium, which result from the volume differences of the cylinders 16, is achieved by a pressure accumulator 63 biased by spring force, the is arranged in this shut-off valve circuit, and the pressure accumulator 63 can through the additional pump 61 can be recharged. It can be seen that every flow medium which can be seen from the system by operating the various valves, can be passed into a common (not shown) storage container, with which is connected to the inlet opening of the auxiliary pump 61 via a filter (64).

Flow medium under pressure for the actuation of the various poppet valves 33 is removed from the main fluid system pressurized by pump 55 obtain. A spring-loaded two-position valve 65 is in a Line 66 arranged, the passages M in each piston rod 20, 21 with a Line connects that connects two of the shut-off valves 59 together, the parallel to the pump openings 57 and 58 are connected. The valve 65 will operated by an electromagnet 65 a with a suitable (not shown) Control circuit of known design is connected, and the valve is designed so that the line 66 is connected to a tank in order to reduce the fluid pressure the poppet valve 33 when the electromagnet 65a is de-energized. The excitement of the solenoid 65a actuates the valve 85 so that the line 66 and the associated valve cylinder 39 are pressurized to the Hold valves 33 in their closed position. It should be noted that the Valves 33 biasing springs 41 are primarily intended to provide a free, To prevent the valves from floating up and down, and to prevent the valves from being opened, when the flow medium is in one or in both chambers of the cylinder 16 below Pressure is set.

The control of the cylinder and piston units lo - 13i by the the units either stopped or in a fast or slow operating mode driven in either direction is driven by a spring force centered three-position valve 70 carried out with open center, the actuating magnet 70a and 70b.

A pump port 57 is with an opening of the valve 70 and with the passages 47 of the piston rods 20, while the other opening 58 with a second opening of the valve 70 and with the passages 46 of the piston rods 21 is connected. The other two openings of the valve 70 are with the relevant Passages 47 of the piston rods 21 and 46 of the piston rods 2c connected. if neither of the solenoids 70a or 70b is energized, leads the open center of the valve 70 to connect all cylinder chambers 25 to 28 with each other, and if the pump 55 runs without conveying flow medium in one direction, findat no relative Movement of the pistons and cylinder units 1o - 13 takes place and the press plates 14 and 15 do not move in relation to each other. while the disclosed embodiment of the invention-for a horizontally arranged press suitable and would be sufficient, it can be seen that for a vertically oriented press For safety reasons, additional valve devices would be required, the one Prevent flow of fluid in relation to the cylinders 16 to avoid a to prevent unintentional movement due to gravity. An illustration is not ticked as necessary, as its installation and training are for the professional is readily apparent.

The operation of the slow motion device according to the invention in a direction determined by the operation of the pump is excited by the Electromagnets 70b and 65a causes. This moves the slide of valve 70, to connect all cylinder chambers 25 and 27 to each other and all chambers 26 and 28 to connect together, and the poppet valves 33 are kept closed, by one transfer of fluid between the chambers of each cylinder 16 to prevent. It can be seen that in the cylinders 39 of the poppet valves Hydraulic force developed the counteracting forces created by the flow medium is developed in the cylinders 16, due to the lower friction losses exceeds and keep the poppet valves closed. If so, the pump 55 is operated so that the opening 57 becomes the pressure port, the plate 15 is in the direction moved onto the fixed plate 14. A reversal of pump operation through which the opening 58 becomes the pressure opening, would also be the direction of the slow movement of the plate 15 reverse. In this slow mode of operation it can be seen that only the chambers 25, 27 or 26, 28 of the cylinders are pressurized, whereby a considerably greater force is generated than is the case with a fast operating mode is possible.

The rapid movement in a determined by the operation of the pump Direction is controlled by energizing the solenoid 70a of the valve 70 while the electromagnet 65a remains de-excited. When the magnet 65a is de-energized is, the valve 65 is in a position in which the in the line 66 located flow medium is conducted to a tank, whereby all the pressure of the flow medium in the poppet valve cylinders 39 is drained. This will it allows the poppet valves 33, as a result of the cylinders 16 existing To open fluid pressure, creating a flow between the two chambers each cylinder 16 is permitted. When the pump 55 is operated to the effect that the port 57 is the pressure port, the plate 15 moves rapidly in the direction on the plate 14.

In this mode of operation, cylinder chambers 25 and 26 are both Units lo and 13 connected to one another, while the cylinder chambers 27 and 28 of the two units 11 and 12 are connected to one another. That in the pump opening 57 pumped fluid under pressure results in a greater net force in the chambers 25 than in the chambers 26 due to the difference in the relative piston area, from which a corresponding movement results. At the same time it opens under pressure standing medium the poppet valves 33 against the force of their biasing springs 41 and allows the required fluid to be transferred from a chamber the other chamber of a cylinder 16.

While the pump 55, the cylinders 16 of the units 1o and 13 fluid supplies, it simultaneously draws flow medium from the cylinders 1B of the other Aggregates 11 and 12. As a result, there is a minimal in the latter aggregates Pressure which, however, is sufficient to move the poppet valves 33 into an open position for the free transfer of the amount of fluid between the cylinder chambers to keep. Any pressure increase required can be obtained from the pressure accumulator 63 that is switched on in the pump circuit.

The disclosed facility is what would be considered a closed facility but an open fluid system can also be used for control. of Operation of the by Strö'mü # gs'- "..

medium operated drive device according to the present invention be used. A particular advantage of the illustrated closed system is that the energy that is developed by the flow medium is pressurized in the cylinders 16, readily by the pump and the electric motor 56 can be distributed. So the electric motor absorbs energy, from the decompression of the flow medium after a sequence of operations with a large Power and low speed is obtained.

Albeit cle valves 65 and 70 as solenoid operated valves are shown, it should be noted that these valves depending on the requirements a particular use can be manually operated valves or the Solenoids can be actuated by a control pressure. One factor in choice the type of valve actuation is the structural arrangement, such as the distance the valves from the operator's stand, or the automation of the system.

It can be seen that an improved fluid actuated one Drive device has been provided by the present invention, which is shown in is able to achieve the desired fast and slow movement at the same time To evoke the development of minimal or maximal forces, in their simplest form Form two piston and cylinder units of essentially the same design used. The drive device requires outside of the cylinder and piston units lo-13 does not have equipment for handling large volumes of fluid, as evidenced by Profitability and effective operation of the system result.

Claims (1)

Claims O by a flow medium actuated drive mechanism with first and second double-acting cylinder and piston units that are in proportion are reciprocable to one another in the axial direction, thereby marked, tr that each piston (17) has a piston rod (18,20 or 18, 21) which in axial Direction of the piston and mechanically rigidly connected to the other Kdbenstange is that the cylinders (16) are mechanically rigidly connected to each other and each Piston the relevant cylinder in first and second chambers (25, 27 or, 26, 28) divided that in each piston a fluid valve (33) in a fluid communication ratio installed between the first and second chambers, the valve is optional is actuatable to either a fluid passage position or a fluid shut-off position take and that with the cylinder and piston units (10-13) a fluid circuit is connected, which is operable, certain cylinder chambers fluid feed under pressure, resulting in a relatively rapid axial movement of the cylinder and piston units with low actuation force leads when the fluid valve (33) is in its flow position, and to a relatively slow axial movement with high actuation force if the valve is in its shut-off position; 2. Drive mechanism according to Claim 1, characterized in that the piston rods are double-ended and through both cylinder chambers extend, with the diameter of the two ends of the piston rods relatively different with regard to the individual cylinder and piston units are, and that the first and benaggregats are relative and that, second cylinder and Piston units (10, 13 or, 11, 12) in, with regard to the larger and smaller Kqlbp n, rods; are aligned opposite to each other: 3. Drive mechanism according to claim 2, characterized in that the piston rods with first and second Fluid passages (45 or 46) are formed which connect from the outside to the fluid circuit are connected and with the first and second cylinder chambers on a Place close to the associated piston. 4, drive mechanism according to claim 2, characterized in that the fluidic valve of each piston has a movable valve element and a contains cooperating valve seat in a fluid passage, and that the piston is further designed so that the valve element through the supply can be pressurized by pressurized flow medium, to hold the valve element in its shut-off position on the valve seat. 5. Drive mechanism according to claim 4, characterized in that the piston rods are formed with a fluid passage (45) which is in connection with the valve and optionally with an external pressure medium source can be connected. 6. Drive mechanism according to claim 2, characterized in that the fluid circuit includes valve means which are in flow control relationship are arranged with the chambers of each cylinder and are selectively operable around either both chambers of a cylinder with a source of pressurized material To connect the flow medium or the chambers at the same end of both cylinders with to connect a source of pressurized flow medium. 7. Drive mechanism according to claim 1, characterized in that several first and second cylinder and piston units provided in pairs are parallel to each other with the fluid circuit for their simultaneous Operation are connected. 8. Drive mechanism according to claim 1, characterized in that the fluid circuit is selectively operable to provide fast or slow propulsion cause in one or the other axial direction.