Oscillation cylinder arrangement

Abstract

The oscillation cylinder arrangement (100) comprises a working cylinder (10A) and a piston with a rod (27A), arranged to move therein, and a control valve structure (20) for the working cylinder (10A). The control valve structure (20) incorporates a main valve (24) for transmitting a pressure medium to a first sub-chamber or a second sub-chamber of the working cylinder (10A) for a linear movement (A, B) of the piston, as well as impulse valves (22, 23), and lever arms (25, 26) for controlling them, in order to set the operational state of the main valve (24). Control members (27B) fixed to the piston rod (27A) moving in the working cylinder (10A), the control members (27B) being arranged to contact the lever arms (25, 26) of the impulse valves in order to define the extreme positions of the movement of the piston rod (27A).

Claims

1. An oscillation cylinder arrangement comprising: a working cylinder and a piston with a rod, arranged to move therein, a control valve structure for the working cylinder, comprising a main valve provided with a channel system for transmitting a pressure medium to a first sub-chamber or a second sub-chamber of the working cylinder for achieving a linear movement of the piston, impulse valves and lever arms for controlling said impulse valves in order to set an operational state of the main valve, and control members fixed to the piston rod, which moves in the working cylinder, and arranged to contact the lever arms of the impulse valves in order to define first and second extreme positions of a movement of the piston rod, wherein an extra volume is provided in the channel system of the main valve in order to keep a control pressure rate at operating level, and wherein the extra volume is provided in the channel system of the control valve structure, in a channel between nozzles and discharge openings of the impulse valves, by enlarging the channel system, and in that each of these sections of the channel system separately have a volume more than 2 times the volume displaced by the spindle of the main valve while moving from the first extreme position to the second extreme position.

2. The oscillation cylinder arrangement of claim 1, wherein the extra volume is provided in the channel system of the main valve by means of additional chambers, boreholes, or projections on the spindle, or boreholes in the spindle, in order to keep the control pressure rate at operating level.

3. The oscillation cylinder arrangement of claim 1, wherein the main valve and the impulse valves are provided in the same control valve structure body in the direction of movement of the working cylinder.

4. The oscillation cylinder arrangement of claim 1, wherein the lever arms used for controlling the impulse valves are arranged to project from the same outer face of the main valve.

5. The oscillation cylinder arrangement of claim 1, wherein the lever arms are arranged to contact the same sector of the control members which is smaller than ⅓ of the area of discharge openings of the impulse valves surrounding the central axis of the oscillation cylinder.

6. The oscillation cylinder arrangement of claim 1, wherein the impulse valves are provided, together with the main valve in the body of the control valve structure, the control valve structure being fittable into a circular sector smaller than ⅓ of the total area of discharge openings of the impulse valves of the oscillation cylinder.

Description

MORE DETAILED DESCRIPTION OF THE EXAMPLES OF THE INVENTION

(1) In the following, the invention will be described in detail. The description refers to the accompanying schematic drawing wherein

(2) FIG. 1 is an exemplary view of a prior-art operational scheme of an oscillation cylinder arrangement,

(3) FIG. 2 is an exemplary view of an operational scheme of an oscillation cylinder arrangement according to the invention,

(4) FIG. 3 is perspective view of way of connecting a control valve structure of the oscillation cylinder according to the invention to second end of the oscillation cylinder, and

(5) FIGS. 4A-4D show four preferred embodiments of a main valve according to the invention.

(6) The embodiments included in the following description are only exemplary, allowing a person skilled in the art to implement the basic idea of the invention in a way differing from the description. Although several places of the description may refer to a specific embodiment or specific embodiments, this does not mean that the reference only is limited to this single embodiment described, or that the disclosed feature only is applicable to this single embodiment described. Combinations of any individual features of two or more embodiments are feasible for creating new embodiments of the invention.

(7) FIG. 1, showing a prior-art operational scheme of an oscillation cylinder solution, has been explained above in the description of the prior art.

(8) FIG. 2 is an exemplary view of an operational scheme of an oscillation cylinder arrangement 100 according to the invention.

(9) The oscillation cylinder arrangement 100 controls the movement of an actuator 3 present in an industrial process. This movement can be, for example, a reciprocal, linear movement of the actuator 3, indicated, in FIG. 2, by an arrow with a head at each end and having extreme positions denoted by letters A and B.

(10) The linear movement is generated by a piston 27 arranged to move back and forth in a working cylinder 10A and connected to a piston rod 27A. In the working cylinder 10A, the direction of the piston's 27 movement, which is either direction A or direction B, is determined by which of the sub-chambers 10A1 or 10A2 of the working cylinder 10A, formed on different sides of the piston 27 and varying in volume, has a higher pressure. A pressure medium flows into the first sub-chamber 10A1 and the second sub-chamber 10A2 through lines 31 and 32, respectively. Preferably, the pressure medium used is compressed air, supplied or discharged, through the lines 31, 32, from a main valve 24 controlling the operation of the working cylinder 10A. The compressed air, which enters from a compressed air grid, is supplied to the main valve 24 from a compressed air inlet 30 of a control valve structure 20.

(11) The main valve 24 controls the flow of the compressed air in the lines 31 and 32. Preferably, a spindle arranged to move from one extreme position to another is provided inside the main valve 24. In the first extreme position of the spindle, the main valve 24 supplies, through the line 31, compressed air into the first sub-chamber 10A1 of the working cylinder 10A, and, at the same, opens up a discharge channel 33 for the air to be discharged from the second sub-chamber 10A2. In the second extreme position of the spindle, the main valve 24 supplies, through the line 32, compressed air into the second sub-chamber 10A2 of the working cylinder 10A, and, at the same, opens up the discharge channel 33 for the air to be discharged from the first sub-chamber 10A1.

(12) The control of the spindle of the main valve 24 is implemented in such a way that impulse valves 22 and 23 operate as pressure discharge valves, alternately discharging pressure from the main valve 24 in order to control the movement of the spindle. However, a small amount of compressed air is continuously flowing from choke nozzles 28A, 28B into that section of the channel system which extends to the impulse valves 22, 23. The choke nozzles refer to a suitable dimension of a point of the channel system. It is essential where this choking portion or point is in the channel system. The nozzles can be either separate from or form part of the channel system. However, because the flow orifice of the impulse valves 22 and 23 is larger than the flow orifices of the choke nozzles 28A and 28B, said impulse valves 22, 23 are, under control, capable of generating a sufficiently quick pressure reduction in order to change the operational state of the main valve 24. The impulse valves 22 and 23 operate, under the control of the lever arms 25 and 26, by means of one or more control members 27B fixed to the piston rod 27A moving in the working cylinder 10A.

(13) For a simpler oscillation cylinder structure, the impulse valves 22 and 23 are provided in the body of the main valve 24. In the preferred embodiment shown in FIG. 2, the lever arms 25 and 26 controlling the impulse valves 22 and 23 are installed in the body of the main valve 24, on two opposite sides of one face thereof, suitably extending to contact the one or more control members 27B fixed to the piston rod 27A moving in the working cylinder 10A. Preferably, the covers of the main valve 24 are simple, plate-like parts. Because, in the control valve structure 20 according to the invention, all the channels required for the control of the valves are incorporated in the body of the main valve 25, the oscillation cylinder arrangement 100 according to the invention has low costs and high operational reliability.

(14) If the spindle of the main valve 24 is provided with seals, there is always some friction there. If the pressure of the compressed air entering the oscillation cylinder arrangement 100 becomes too low, there is a danger of the pressure, generating the movement of the control spindle of the main valve 24 and present in the volume between the nozzle and the impulse valve, not being sufficient to effectively push the spindle into the second extreme position. Consequently, the direction of movement of the working cylinder cannot be changed.

(15) To avoid this fault situation in the oscillation cylinder arrangement 100 according to the invention, an additional volume is provided in the compressed-air filled section of the channel system extending from the nozzles 28A, 28B to the impulse valves 22, 23. Preferably, additional volumes can be created by enlarging the diameter of the channel system, or, by providing extra boreholes, referred to by 21A and 21B, or chambers 29A, 29B as additional compressed-air reservoirs, in the channel system. In a preferred embodiment of the invention, an extra volume can be machined in each end of the spindle of the main valve 24, for example by providing them with boreholes, as shown in FIG. 4B, or by adding stroke-length limiting projections, as shown in FIG. 4A, or, by limiting the movement of the spindle in some other way, as shown in FIGS. 4C and 4D. Preferably, the volume of the resulting air reservoirs is more than 2 times the volume displaced by the spindle of the main valve (24) during its movement from one extreme position to the other.

(16) FIG. 3 is perspective view of the oscillation cylinder system 100 according to the invention. The piston 27 provided in the working cylinder 10A moves reciprocally in direction A.Math.B. A preferably annular control member 27B is provided in the end of the piston rod 27A shown in FIG. 3. The control valve structure 20 is attached to the second end 10B of the working cylinder, being situated, in the example shown in FIG. 3, below the piston rod 27A. As the piston rod 27A travels far enough in direction A, the control member 27B provided on the piston rod 27A eventually hits the lever arm 25 of the impulse valve 22. As the tip of the lever arm 25 moves in direction A, the discharge valve of the impulse valve 22 is opened. The impulse valve 22 generates a pressure reduction which guides the spindle of the main valve 24 to a position that causes the compressed air in the first sub-chamber 10A1 of the working cylinder 10A to lead its way out of there. Now, the higher pressure of the compressed air led into the second sub-chamber 10A2 of the working cylinder 10A turns the movement of the piston rod 27A in direction B. As the control member 27B provided on the piston rod 27D reaches, after a while, the lever arm 26 of the second impulse valve 23, the movement of the piston rod 27A, as described above, turns in direction A again.

(17) FIGS. 4A, 4B, 4C and 4D show alternative embodiments of the invention for providing an additional volume in the control channel systems.

(18) FIG. 4A shows a preferred embodiment of a spindle 240A of a first main valve 24A according to the invention. Pin projections are provided in both ends of the spindle 240A. The pin projection 240A1 creates an additional volume 29A1 in the first end of the main valve 24A. The pin projection 240B1 creates an additional volume 29B1 in the first end of the main valve 24A.

(19) FIG. 4B shows a preferred embodiment of a spindle 240B of a second main valve 24B according to the invention. Cavities are drilled in both ends of the spindle 240B. The drilled cavity 29A2 creates an additional volume in the first end of the spindle 240B the main valve 24B. The drilled cavity 29B2 creates an additional volume in the second end of the spindle 240B of the main valve 24B.

(20) FIG. 4C shows a preferred embodiment of a spindle 240C of a third main valve 24C according to the invention. Cavities having a smaller diameter than the diameter of the spindle 240C of the main valve 24C are provided in both ends of the main valve 24C. Hence, both ends of the main valve have shoulders defining the extreme positions of the spindle 240C. A cavity 29A3 unreachable by the spindle 240C is provided in the first end of the main valve 24C. Correspondingly, a cavity 29B3 unreachable by the spindle 240C is provided in the second end of the main valve 24C.

(21) FIG. 4D shows a preferred embodiment of a fourth main valve 24D and a spindle 240D according to the invention. In this embodiment, pin projections directed towards the spindle 240D are provided in both ends of the body part of the main valve 24D. The pin projection 240D1 creates an additional volume 29A4 in the first end of the main valve 24D. The pin projection 240D2 creates an additional volume 29B4 in the first end of the main valve 24D.

(22) The outer dimensions of the control valve structure 20 utilized in the oscillation cylinder arrangement 100 are so small that it fits into a circular sector smaller than ⅓ of the area of the circular rear end 10B of the working cylinder 10A.

(23) The above describes preferred embodiments of the oscillation cylinder solution according to the invention. The invention is not restricted to these embodiments but the inventive idea has numerous applications within the scope defined by the claims.