JP4292415B2 - Hydraulically operated brake exhaust valve - Google Patents

Description

  The present invention is an exhaust valve of a two-cycle large-sized diesel engine that is movable up and down in the axial direction and rotatable about a shaft, and is movably supported in a valve casing by a valve rod. A rotating device and a braking device for braking the end of the valve opening movement are provided, the braking device having a braking piston coupled to the valve stem, the braking piston opening the exhaust valve under the action of the lifting actuator The present invention relates to an exhaust valve configured to be fitted into a corresponding brake chamber filled with fluid just before the end of movement.

  In this type of known exhaust valve, the valve stem is provided with a rotary blade protruding into an exhaust discharge passage penetrated by the valve rod in order to realize a rotational motion, and the rotary blade is rotated by exhaust gas flowing through. Get exercise. In this case, energy is deprived from the exhaust, and energy is insufficient when the exhaust turbocharger is driven later, so that only a relatively low charge pressure is achieved.

  From the specification of Japanese Patent Application Laid-Open No. 61-083404, the valve stem is provided with a drive wheel formed in a so-called Pelton wheel at the upper end of the valve stem in addition to the above-described rotor blade, and the drive wheel is made by a pump Exhaust valve devices that are subjected to the action of a discharged fluid jet are known. In this case, the energy required for driving the pump also causes an output loss.

  From JP-A-59-47581, an exhaust valve is known in which the closing motion is braked. In this case, the upper end of the braking piston coupled to the valve stem is just before the end of the valve closing motion. The brake piston has a flow path leading to a nozzle arranged in a tangential direction and fitted into a brake chamber that is acted upon by a fluid, so that rotation of the valve occurs when seated on the corresponding valve seat. In this case, the brake chamber makes it difficult to mount a lifting actuator provided above the brake piston. Further, in this case, it is disadvantageous that the valve closing movement is hindered.

  Starting from the above points, the object of the present invention is to improve a valve of the aforementioned kind by simple and inexpensive means, without consuming effective energy and nevertheless achieving a reliable rotational movement when the valve is open. It is to make it.

  The object is according to the invention, wherein the brake piston for braking the opening movement of the exhaust valve comprises at least one flow path starting from the front end face of the piston fitted into the brake chamber in the exhaust valve opening direction, the flow path having a radius This is solved by extending in a direction different from the direction and opening at the outer periphery of the brake piston.

  Preferably, the above measures result in a rotating device which is built into the braking device and operates on the reaction principle. In this case, since the brake piston has a relatively large diameter, a relatively large pressure is also generated in the flow path when it is fitted into the brake chamber. Therefore, the jet generated by this and flowing out from the end of the flow path on the outer peripheral side of the piston produces a large impulse, which results in a reliable valve rotation over a desired angle together with a high torque. Since the pressure used for the rotation of the valve is produced by braking the end of the opening movement of the valve, there is an advantage that no effective energy is consumed. In addition, the closing movement is not hindered by this, so that a reliable closing stroke is ensured. On the other hand, the use of the braking device avoids a violent collision of the valve with the rigid stopper, so that a slow operating mode is ensured even when a high pressure is used to open the valve.

  Preferred embodiments and preferred developments of the measures are set out in the subclaims. In this case, one of the particularly suitable measures is that the piston outer peripheral side end of the flow path provided in the brake piston is separated from the end surface of the brake piston opposite to the brake chamber in the axial direction. This measure preferably results in a two-stage braking action. In other words, as long as the opening on the outer peripheral side of the flow path is not covered by the side wall of the brake chamber, a rotational motion of the valve occurs and at the same time a constant braking action is achieved. Furthermore, this braking action is enhanced as soon as the braking piston is inserted deeper into the braking chamber and the opening of the flow path is covered.

  Yet another preferred countermeasure is that at least one flow path is formed as a hole or a connecting hole that extends in a direction parallel to the tangent and opens to the outer peripheral side of the piston. These holes can be accurately produced by an easy method. Yet another countermeasure is that at least one flow path is formed as a groove provided on the outer periphery of the piston. Such grooves are preferably particularly easy to produce.

  The valve is preferably provided with a hydraulic actuator formed by a piston coupled to the valve stem and a casing lumen. The casing lumen is formed as a protruding part of the storage chamber corresponding to the brake piston, preferably subjected to the action of a fluid formed by lubricating oil, facing the brake chamber, in which case the storage chamber is a fluid It has an inflow port and a fluid outflow port. This ensures a reliable supply of the required fluid to the braking chamber formed as a downward projecting part of the storage chamber.

  Other preferred embodiments and suitable developments of the measures are set forth in the other subclaims, the details of which will be taken from the following exemplary description based on the drawings.

  The main application area of the present invention is, for example, a two-cycle large diesel engine used as a marine drive device. Since the basic structure and mode of operation of this type of engine are known per se, a detailed description in connection with the present invention will not be necessary.

  This type of engine typically has a plurality of sequentially arranged cylinders. The basic cylinder of FIG. 1 includes a combustion chamber 1, and the upper limit of the combustion chamber is formed by a cylinder cover 3 mounted on a cylinder liner 2. The cylinder cover includes an exhaust discharge port 4 disposed coaxially with the cylinder shaft, and an exhaust valve 6 that cooperates with a valve seat 5 is disposed at the exhaust discharge port. The exhaust valve is used to control opening and closing of the exhaust discharge port 4. Therefore, it can be moved up and down and at the same time is rotatable to keep the sealing surface clean. Such movement is represented in FIG. 1 by arrows indicating movement. In FIG. 1, the valve 6 is shown in the closed position, in which the valve head 7 is in close contact with the seating surface of the corresponding valve seat 5 with the orbiting valve surface.

  The valve 6 is supported in a valve casing 9 mounted on the cylinder cover 3 so as to be movable in the axial direction and rotatable in the circumferential direction by a valve rod 8 protruding coaxially upward from the valve head 7. The valve stem 8 penetrates into an exhaust passage 10 continuous with the exhaust discharge port 4, and a guide bushing device 11 corresponding to the valve stem 8 is provided on the upper road wall portion of the exhaust passage. It penetrates the bushing device. The valve stem 8 penetrates into a head casing 12 mounted on the valve casing 9, as best seen from FIG. 2, with a portion protruding from the guide bushing device 11. Includes a lifting actuator, a return device and a braking device arranged on the valve 6, in which a rotating device is incorporated. The lifting actuator is formed as a hydraulic unit and includes a piston 13 attached to the upper end of the valve stem 8, which is disposed in the lumen 14 of the head casing 12 and forms the lower limit of the operating chamber 15. The working chamber is loaded with high pressure hydraulic fluid as suggested by the hydraulic supply arrow 16. A pump may be provided as a hydraulic pressure source. It is also possible to provide a common rail which is preferably used as a hydraulic pressure source, and branch pipes each having one valve communicate with each working chamber 15 from the common rail. In this case, the valve 6 can be subjected to the action of a very high pressure that remains constant throughout the opening stroke.

  The inner cavity 14 including the working chamber 15 is formed as an upward projecting portion of a housing chamber 17 having a larger diameter and provided coaxially with the valve shaft in the head casing 12. The portion of the valve stem 8 that passes through the receiving chamber 17 carries a brake piston 21 that fits into the corresponding ring-shaped brake chamber 22 at the lower end of the opening movement of the valve 6. The brake chamber is formed as a downward projecting portion of the storage chamber 17 that is coaxial with the valve shaft and faces the inner cavity 14, and is penetrated by a valve stem 8 that is coaxial with the valve shaft.

  The receiving chamber 17 is subjected to the action of a fluid that also fills the braking chamber 22. In the illustrated example, the fluid used is a lubricating oil supplied from a low pressure lubricating system having a low pressure of 0.3 bar, which is relatively low compared to the high pressure of the hydraulic fluid supplied to the working chamber 15. The The lubricating oil is guided through the containment chamber 17, so that the containment chamber has at least one inlet 18 and at least one outlet 19, here two outlets 19 arranged one above the other. is doing. Since these outlets are located above the braking chamber 22 and spaced from the chamber, the receiving chamber 17 is always filled with lubricating oil exceeding the height of the braking chamber 22, and at the same time, The braking chamber 22 that does not have the lubricating oil outflow inlet and is supplied only from the storage chamber 17 is surely filled with the lubricating oil. As indicated by the liquid level line 20, the oil supply to the storage chamber 17 is performed up to the position of the upper outlet 19 where the breathing is also performed.

  The two outlets 19 are joined to one pressureless reflux oil collecting pipe 23, and the oil leaking into the gap between the piston 13 and the inner lumen 14 corresponding to the piston and the valve stem 8 and the Oil leakage that penetrates through the valve rod and enters the gap between the bushing device 24 and the bushing device 24 that precedes the brake chamber 22 is also discharged through the reflux oil collecting pipe. The reflux oil collecting pipe 23 joins the circular ring path 25, and the circular path includes a discharge port 26. The head casing 12 has an oil sump chamber 27 penetrated by a valve stem 8 below a region including the accommodating chamber 17 having a braking chamber 22, and leaks into a gap between the valve stem 8 and the bushing device 24. Oil is received in the sump chamber. The oil sump chamber 27 is connected to the circular ring passage 25 as suggested by the connecting pipe 27a.

  The pressurizing stroke of the working chamber 15 causes the valve 6 to move downward together with the piston 13, thereby pulling the valve 6 away from the valve seat. In the final stage of this opening movement, the braking piston 21 is fitted into the corresponding braking chamber 22, which slows down the opening movement of the valve 6 and avoids a violent collision with the rigid stopper, so that A slow operating mode is ensured despite the high pressure load. A return device is provided for closing the valve 6, which returns the valve 6 when the pressure in the working chamber 15 drops. The return device may be formed as a return spring. In the illustrated example, the returning device is formed as a pneumatic unit provided in the oil reservoir chamber 27, which includes a piston 28 attached to the valve stem 8, and an oil reservoir chamber 27 having an upper limit. The working chamber 29 is formed by a lumen that continues downward. The working chamber passes through a supply pipe and is pressurized or decompressed by compressed air at a stroke opposite to the pressurizing stroke of the working chamber 15. For this purpose, the working chamber 29 comprises an inlet 30a connected to a compressed air source and a compressed air outlet 30b.

  The head casing 12 is preferably formed into a multi-body type. In the illustrated example, the head casing 12 has an oil sump from an upper member 12a corresponding to the lifting operation device, a lower member 12b corresponding to the pneumatic unit forming the return device, and a joint between the upper member and the lower member. It includes a braking chamber 22 and a central member 12c that forms a bushing device 24 that is placed in front of the chamber, and is fitted into an upper extension of the inner cavity of the lower member 12b that forms the chamber 27. The working chamber 29 containing the piston 28 preferably continues below the sump chamber 27.

  In order to prevent deposits generated on the sealing surfaces of the valve head 7 or the valve seat 5 from adhering to each other, the valve 6 is rotated by a certain angle just before the end of the open stroke movement during each lifting movement. In this case, it is usually sufficient to rotate by a relatively small angle of 10-20 °. This rotational movement is realized by the braking pressure generated when the brake piston 21 is fitted into the corresponding brake chamber 22. For this reason, the brake piston 21 has at least one flow path 31 starting from the piston end surface on the brake chamber side, and the flow path extends in a direction different from the radial direction and is located in the housing chamber 17 on the outer periphery of the brake piston 21. Is open. In this case, it is preferable that the plurality of flow paths 31 of this kind are arranged evenly on the outer periphery of the brake piston 21, and preferably two such flow paths 31 arranged 180 ° apart from each other. It is good to be provided. By such measures, the valve 6 achieves a desired rotation at the final stage of the opening movement.

  In the embodiment shown in FIGS. 3 and 4, the flow path 31 is formed by a plurality of series of holes or a plurality of connecting holes comprising blind holes 32a and 32b connected to each other. This type of hole can be easily produced with high accuracy. In the illustrated example, the connecting hole includes a blind hole 32a parallel to the axis, starting from the braking chamber side end surface of the lower side of the braking piston 21, respectively, as can be fully seen from FIGS. Since the blind hole intersects with the blind hole 32b starting from the outer periphery of the brake piston 21 and in a plane parallel to the end face of the brake piston, a flow path that forms one continuous flow path 31 is generated. The end of the flow path on the piston outer peripheral side is parallel to the tangent and parallel to the end face, and thus forms a horizontal nozzle 33 here, and oil that flows into the flow path when the brake piston 21 is fitted into the brake chamber 22. , As suggested by arrow 34 in FIG. 3, is jetted into the receiving chamber 17 through the nozzle in the form of a jet parallel to the tangent and parallel to the end face. As a result, the reaction impulses produced respectively result in the desired rotation of the valve 6. Obviously, instead of a connecting hole consisting of a vertical hole parallel to the axis and a horizontal hole parallel to the tangent line, a single hole directed obliquely downward from the outer periphery of the brake piston 21 in a direction parallel to the tangent line is provided. It would also be possible to provide it.

  In the embodiment shown in FIG. 5, in order to form the flow path 31, an outer peripheral groove 35 that extends obliquely upward starting from the lower end surface of the brake piston 21 is provided. The depth of these grooves 34 preferably decreases continuously in the upper end region of the groove 34, as suggested on the right of FIG.

  As specifically shown in FIGS. 4 and 5, the outer peripheral side end of the flow path forming the flow path 31 is separated from the end surface of the brake piston 21 opposite to the brake chamber 22 by a distance a. Is preferred. As a result, the brake piston 21 is fitted into the brake chamber 22 to a depth corresponding to the thickness of the brake piston obtained by subtracting the above-described distance between the upper end of the outer peripheral side end of the flow path 31 and the upper end surface of the brake piston 21. Or, the opening on the outer peripheral side of the flow path 31 is immediately closed by the side wall of the braking chamber 22, and as a result, the reaction action previously generated disappears. Therefore, from this measure, a two-stage braking action, that is, a low braking effect occurs while the flow path 31 is open, and a high braking effect occurs after the flow path 31 is closed.

  Needless to say, a part of the flow path 31 provided in the brake piston 21 is opened at a certain distance from the piston upper end face, and a part of the flow path 31 is continued from the piston lower end face to the piston upper end face. I can do it.

It is a fragmentary sectional view of an exhaust valve device of a two cycle large diesel engine. FIG. 2 is a cross-sectional view of an operating device, a returning device, a braking device, and a rotating device arranged in the exhaust valve device shown in FIG. 1. It is the figure which looked at the brake piston of the apparatus shown in FIG. 2 from the lower side. FIG. 4 is a side view of the brake piston shown in FIG. 3. It is a side view of a separate brake piston provided with an outer peripheral groove.

Claims (11)

An exhaust valve of a two-cycle large-sized diesel engine that is movable up and down in the axial direction and rotatable about a shaft, and is movably supported in a valve casing (9) by a valve rod (8). A return device, a rotation device and a braking device for braking the end of the valve opening movement, the braking device having a braking piston (21) coupled with a valve stem (8), said braking piston being said lifting piston A brake piston for braking the opening movement of the exhaust valve in an exhaust valve configured to be fitted into a corresponding braking chamber (22) filled with fluid just before the end of the opening movement of the exhaust valve under the action of the actuator. 21) comprises at least one flow channel (31) starting from the end surface of the lower brake chamber (22) on the lower side of the brake piston (21), the flow channel being in a direction different from the radial direction An exhaust valve, characterized in that is open at the outer peripheral side of the brake piston (21) extends.   2. A plurality of flow passages (31) arranged evenly on the outer periphery of the braking piston (21), preferably two flow passages (31) arranged 180 ° apart from each other. An exhaust valve characterized by that.   The exhaust valve according to any one of the preceding claims, wherein the opening position of each flow path (31) is at a position spaced from the upper end surface of the brake piston (21).   The nozzle (33) according to any one of the preceding claims, wherein the at least one flow path (31) is formed as a hole or a connecting hole (32a, b), and the exhaust valve is rotated by a hole opened on the piston outer peripheral side. An exhaust valve characterized in that is formed.   5. The connecting hole according to claim 4, wherein the connecting hole has a blind hole (32a) parallel to an axis, starting from a braking chamber side end face of the braking piston (21), and the blind hole starts from an outer periphery of the braking piston (21). An exhaust valve characterized by intersecting a blind hole (32b) parallel to the tangent and parallel to the piston end face.   Exhaust valve according to any one of the preceding claims, wherein at least one flow path (31) is formed as a groove (35) provided on the outer periphery of the piston.   The exhaust valve according to claim 6, wherein the depth of the groove (35) decreases toward the upper end.   Exhaust valve according to any one of the preceding claims, characterized in that oil can be supplied to the braking chamber (22).   9. Exhaust valve according to claim 8, characterized in that lubricating oil can be supplied to the braking chamber (22).   In any one of the preceding claims, the braking chamber (22) is formed as a downward projection of a receiving chamber (17) corresponding to the braking piston (21) through which a fluid as a braking medium, preferably lubricating oil, flows. The containment chamber has an inner diameter larger than the diameter of the brake piston (21) and has one inlet for fluid and at least one outlet (above the brake chamber (22) spaced apart from the chamber). And 19) an exhaust valve.   In any one of the preceding claims, the lifting actuating device, the returning device and the braking device incorporating the rotating device are arranged in a head casing (12) mounted on a valve casing (9), The head casing is a central member (12c) that forms a braking chamber (22) coaxial with the valve shaft, and is fitted into the inner cavity of the upper member (12a), the lower member (12b), and the lower member (12b). An exhaust valve characterized by comprising:

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