JP2008261364A - Stuffing box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stuffing box for a piston rod used for a cross head diesel engine having excellent maintainability by reducing the size and weight of and making flexible an oil scraping ring fitted therein to reduce the consumed amount of oil and prolong the service life. <P>SOLUTION: The body of the oil scraping ring fitted to the lower one of a plurality of ring grooves formed inside the casing of the stuffing box is so formed that the axial width is 5 to 15 mm and the radial thickness is 17 to 23 mm. Since the size and weight of the oil scraping ring are reduced and the flexibility thereof is increased, the inertia weight is reduced. Consequently, the initial running-in on a piston rod is improved, and the follow-up capability to the operation of an engine is increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stuffing box used in a crosshead type diesel engine or the like.

  In a reciprocating internal combustion engine, power is transmitted by burning fuel in a cylinder and transmitting energy generated thereby to a main shaft via a crankshaft. In this transmission system, a piston rod is attached to the piston, the end of the piston rod is connected to a connecting rod via a crosshead, and the reciprocating motion of the piston rod is converted into a rotational motion to transmit power, which is called a crosshead type. There is something.

  Since the crosshead type two-cycle diesel engine has a simple structure, good combustion efficiency and many advantages, this type is mostly used in large marine engines. The fuel is a low quality fuel, C heavy oil with high viscosity, high sulfur and poor stability.

  For lubrication of each part of the crosshead type two-cycle diesel engine, since the cylinder portion and the crankcase are separated, separate oil supply passages are required for the cylinder liner and each part in the crankcase. The oil supplied to the cylinder liner is called cylinder oil, and the oil supplied to each part of the crankcase is called system oil. In the operation of this engine, the above-mentioned C heavy oil is used as fuel, so that combustion cylinder oil as a lubricating oil is contaminated by combustion gas and combustion residual oil, and in order to prevent this contaminated cylinder oil from entering the crankcase, combustion is performed. A partition plate is provided between the chamber side and the crankcase side. Further, a sealing device called a staffin box is mounted immediately above the piston rod.

  The stuffing box is formed of a split-type main body exterior <casing> 71 and split-type inner rings 10 and 11 as shown in FIG. 4 as an example of the general shape disclosed in Patent Document 1. However, the inner ring comprises a seal ring 10 for gas sealing and an oil scraping ring 11 for scraping off excess system oil adhering to the piston rod 2 to keep the lubricating oil film properly, Multiple stages are installed. The oil scraper ring 11 has a plurality of oil passage holes formed in the center of the cross section in the radial direction.

  Of the ring grooves to which the oil scraping ring of the stuffing box is mounted, a communication hole 17 is provided in the first-stage ring groove from the top, and the cylinder oil contaminated by the combustion residual oil entering from the top, and the oil scraper The mixed oil of the system oil that has entered without being scratched by the ring 11 is discharged to the outside from the communication hole 17. In the lower ring groove, the oil scraped off from the piston rod is collected at the bottom of the ring groove through the oil passage hole of the oil scraper ring, and returned to the crankcase by the drain hole 12 provided on the outer periphery of the ring groove.

  The specifications required for a general stuffing box are described in detail in Patent Document 2, but in summary, proper separation of system oil and cylinder oil, proper sealing of the upper combustion flame and scavenging pressure, Seal to prevent cylinder oil from entering from above, scraping system oil into the crankcase, avoiding oil turbidity by sealing the impact pressure of the crosshead, long life, reducing oil consumption, minimizing piston rod wear There are conditions such as.

  Each ring incorporated in the stuffing box has been achieved by the selection of appropriate materials and manufacturing techniques with precise design techniques and high precision. That is, in order to achieve reliable airtightness and oil scraping action (wiping action) required for the stuffing box, each ring is manufactured by finally cutting a metal material such as cast iron or copper alloy, The inner peripheral surface of each ring maintained a constant relationship with the piston rod with high accuracy. Furthermore, it has two or more multi-divided structures so that it can be mounted from the side of the piston rod, and is fixed integrally by a coil disposed on the outer periphery. About the leak from the joint which is said division | segmentation part, or a blow-through, the design which prevents this is made. In order to prevent leakage in the axial direction, there is a structure in which two pieces are overlapped as shown in each ring of FIG. In the radial direction, a small piece is arranged at the outer peripheral end of the joint, and this is fixed and sealed with the above coil.

In the conventional stuffing box, each ring maintains its exact relationship with the piston rod, so even if it is divided as described above, it is mounted in each ring groove in the casing and clamped to the side of the ring groove It was designed to function as an annular rigid body. For this reason, the piston rod that moves up and down at the start of operation of the engine may be somewhat swung, but if the mass of the ring alone is excessive, the ring follows the movement of this piston rod with a delay, The relationship with the rod cannot be maintained and may cause intense friction. Further, in this case, the piston rod may be scratched in some cases, which may be a factor for reducing the airtightness.
JP 60-18664 A Japanese Patent No. 3083558

As described above, the conventional stuffing box and the ring mounted therein are designed to make the ring itself a rigid body and forcibly become familiar with the rod.
The present invention is a piston rod stuffing box used in a crosshead type diesel engine or the like, and the ring mounted inside is made small, light and flexible, thereby reducing oil consumption and extending the service life. It is an object to provide a stuffing box with excellent properties.

The present invention provides a piston rod stuffing box for a crosshead type diesel engine in which a seal ring is incorporated in each of the upper stages of a plurality of ring grooves formed in the casing, and an oil scraping ring is incorporated in each of the lower ring grooves. In
The oil scraping ring main body is divided into at least two in the circumferential direction, the cross-sectional shape has an axial width of 5 mm or more and 15 mm or less, and a radial thickness including a separate rail part is 17 mm or more. It is 23 mm or less.
In particular, in the case of marine internal combustion engines, the diameter of the piston rod has a standard dimension that has been widely used. In the oil scraping ring adjusted to the minimum diameter of this standard, the outer diameter of the coil is required to be 5 mm or more due to the tension of the coil required to hold the ring. In order to receive this coil by the ring body, the width of the ring body also needs to be 5 mm or more. Similarly, for a piston rod standard having a large diameter, a coil winding diameter of about 15 mm is sufficient for that requirement. Further, the oil scraping ring attached to the stuffing box has a contact surface to the ring groove on the upper and lower side surfaces. The rail part of the oil scraping ring resists the sliding of the piston rod and gives a twisting force to the ring body when functioning the oil scraping with sufficient flexibility. Twist can be suppressed by maintaining the surface pressure on the side of the ring groove of the box. Here, in order for the oil scraping ring to be stably held in the ring groove and to function, the radial thickness of the oil scraping ring body needs to be 17 mm or more and 23 mm or less, preferably 20 mm. The inventor found out as a result of research.
As described above, the diameter of the piston rod has a standard size that has been widely used. However, the stuffing box of the present invention and the oil scraper to be mounted on the piston rod have a piston rod of any diameter of any standard. The same effect can be demonstrated by using the same cross-sectional shape only by changing the inner peripheral diameter for the rod to pass through.

The present invention is characterized in that the oil scraping ring is attached to at least one or more including the lowest step of the continuous ring groove.
In order to exhibit oil scraping performance more stably, the oil scraping ring of the present invention requires 3 to 6 stages, preferably 4 stages.

The present invention is such that the outer diameter of the ring groove bottom of the seal ring on which the oil scraping ring is mounted is substantially equal to the outer diameter of the groove bottom of the seal ring or larger than the outer diameter of the groove bottom of the seal ring. It is characterized by setting.
According to the said structure, the outer periphery of the main body of the oil scraper ring to mount | wear and the space | gap of a ring groove bottom can be ensured more largely than before as temporary oil storage space.

The present invention is characterized in that a groove bottom lower side surface of a ring groove on which the oil scraping ring is mounted is inclined downward toward a radially outer side.
The lower surface of the ring groove is inclined radially outward with the outer peripheral end of the horizontally processed ring clamping portion as a base point and joined to the vertical wall surface at an appropriate angle R to form an oil storage space. The angle of the inclined surface is determined freely depending on the oil storage volume required for the function and the range of dimensions allowed for the casing, but the angle at which the oil scraped by the ring can be discharged more reliably without stagnation. It has been found from the inventor's verification that the angle is within the range of 5 to 40 degrees, preferably 10 degrees.

According to the present invention, two or more groove bottoms including at least the lowest step of the ring groove on which the oil scraping ring is mounted are communicated to the crankcase in the engine lower layer by a drain hole opened in parallel with the stuffing box central axis. It is characterized by.
Several stages of oil scraping rings are installed in the stuffing box. Since there is a high possibility that substances other than system oil will be mixed with the bottom of the uppermost ring groove on which the oil scraping ring is mounted, this groove bottom is not communicated with the crank chamber. Therefore, the other ring groove bottoms are communicated with each other through a drain hole opened in parallel with the center axis of the stuffing box, and the oil scraping ring reliably guides the system oil scraped from the piston rod to the crankcase. A plurality of drain holes are desirably arranged at equal intervals on the same circumference of the ring groove bottom.

The present invention is characterized in that a plurality of slits communicating in the radial direction from the inner peripheral surface toward the outer peripheral surface are provided on either or either one of the upper side surface and the lower side surface of the oil scraping ring main body.
There is also an oil through hole in the center of the ring body, but the slit on the upper side of the ring body is the oil scraped off by the upper ring, and the slit on the lower side is above and below the ring. The oil scraped off by the lower rail of the rail portion can be guided to the ring groove bottom through the ring body. The arrangement of the slits on the circumference is determined so that the upper and lower sides do not overlap in consideration of the strength of the ring main body, and the number may be appropriately set according to the amount of oil passing therethrough.

The oil scraping ring to be mounted on the stuffing box of the present invention is small and light, and at the same time, the flexibility has been increased. The oil scraping ring of the present invention also has two or more divided structures on the circumference for maintenance as in the conventional case, but since the flexibility has been increased as described above, the joints are also in close contact with each other. The conventional gap cannot be made. For this reason, it is not necessary to make a two-layer structure in order to close the joint, and the component configuration can be further simplified.
Further, during the operation of the internal combustion engine targeted by the present invention, a lateral vibration is applied to the piston rod that moves up and down via the cross head due to an impact at the time of combustion explosion. Due to this vibration, the load applied to the oil scraping ring of the present invention by the piston rod outer surface is the same as that of the conventional oil scraping ring. However, the improvement in the followability due to the reduction of the inertia weight is also advantageous for the shake in the lateral direction (direction perpendicular to the piston reciprocating motion). That is, the conventional oil scraping ring with a large inertia weight cannot follow the vibration of the piston rod, and the surface pressure between the piston rod and the rail portion of the oil scraping ring instantaneously decreases, so that the oil scraping performance is improved. Although the oil scraping ring according to the present invention has been lowered, the followability to the shake is improved, so that the performance of the oil scraping ring can be maintained more stably.
Furthermore, stably maintaining the proper positional relationship between the piston rod and the oil scraping ring can make the scraping function more reliable, resulting in less contamination and unnecessary consumption due to oil turbidity. Together with oil, it can improve the life of the ring itself.

  Here, even if attention is paid to the oil scraper mounting portion of the stuffing box of the present invention, this difference in inertia weight is advantageous. That is, generally, a slight gap is inevitably generated in the axial width of the ring groove and the oil scraping ring in terms of machine manufacture. When the engine is in operation, the oil scraping ring follows up and down movement of the piston rod and is worn by hitting up and down between the gaps. That is, the oil scraper attached to the stuffing box of the present invention is reduced in weight and thus has reduced inertia weight, so it is advantageous for wear against the hit and the life can be extended.

  Moreover, the oil scraping ring of the stuffing box of the present invention can improve the flexibility of the ring by reducing the cross-sectional area of the ring body. This is contrary to the conventional idea of maintaining a rigid and highly circular body, so that the split structure is mounted with a coil having an appropriate tension. Can be formed. For this reason, it is possible to maintain a permanent and appropriate relationship for maintaining an appropriate oil film even for a piston rod whose section has been worn into an ellipse after a long period of operation from the beginning of a new construction.

As described above, according to the present invention, in a stuffing box used in a crosshead type diesel engine or the like, the inertia weight is reduced and the flexibility of the ring main body is reduced by reducing the size and weight of the oil scraper ring mounted in the ring groove. By improving the performance, it is possible to stably maintain the relationship between the oil scraping ring and the piston rod from the beginning to the end of its life, so that the oil scraping is made more reliable and the oil consumption is reduced. Piston rod wear and damage can be reduced. As a result, the life of the ring can be extended, the weight of the stuffing box itself can be reduced, the frequency of ring replacement can be reduced, and maintainability can be improved.
Moreover, the stuffing box itself can be reduced in size and weight by reducing the size of the ring accommodated in a plurality of stages.
In the present invention, the application is limited to the oil scraping ring, but it can be easily applied if there is some knowledge about the seal ring, and it goes without saying that further effects can be expected when combined with the present invention. It is.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a stuffing box showing an embodiment of the present invention, and shows a symmetrical right half.
The seal ring 210 is formed in the upper three stages of the ring, and the first-stage seal ring 211 has a special cross-sectional shape because it has a scraper function for removing foreign matters. It has a function and seals leakage of cylinder oil supplied to the gas seal and cylinder liner. And the groove bottom in the radial direction outermost periphery of the ring groove holding the ring is set so as to secure a predetermined oil storage space 280 on the outer periphery of the ring.
The oil scraping ring 110 is formed in the lower four stages of the ring. The uppermost oil scraping ring 111 of the four stages is cylinder oil contaminated by combustion residual oil entering from the upper part, and is scraped off by the oil scraping ring First, the mixed oil of the system oil that has entered is discharged from the drain hole 170 to the outside. FIG. 2 shows details of the lower three-stage oil scraping ring 110 excluding the uppermost stage in detail. The function of the system oil scraped from the piston rod 90 (not shown) is oil through-hole 112, upper slit 113, lower side The oil is collected in the oil storage space 180 at the bottom of the ring groove through the slit 114 and returned to the crankcase (not shown) by the drain hole 120 provided on the outer periphery of the ring groove. The upper slit 113 and the lower slit 114 are not arranged at the same position on the circumference of the ring main body 110, but are shown in the same cross section for the sake of simplicity.
Each ring is divided into a plurality of parts on the circumference so that it can be attached to the piston rod 90 from the side, and is held with an appropriate tension by an extendable coil 300 disposed on the outermost periphery of the ring body. .

  Table 1 compares the specifications of Example 1 with the conventional example. In the first embodiment, the cylinder diameter is 600 mm, and the diameter of the piston rod is 235 mm. In the first embodiment, the ring body of the oil scraping ring 110 is made of cast iron, and the structure is divided into three in the circumferential direction. Since the cross-sectional shape is 14 mm in width 150 and 19 mm in radial thickness 140 including the rail part, 30% reduction in the axial direction and about 12% reduction in the radial direction are achieved compared to the conventional ring of the same standard. It was. As a result, according to the specification of Example 1, the weight per oil scraping ring could be reduced by about 1 kg as compared with the conventional two-sheet structure. In the stuffing box of the first embodiment, since four oil scraping rings are used per cylinder, a total weight reduction of about 4 kg can be achieved.

Table 1: Comparison of dimensions between the prior art and Example 1

In the first embodiment, the groove bottom diameter on which the oil scraper ring 110 is attached is 314 mm, which is 8 mm larger than the groove bottom diameter 306 mm on which the seal ring 210 is attached. Accordingly, since the outer peripheral diameter of the ring main body of the oil scraping ring 110 is 273 mm, a clearance of 20.5 mm can be secured at the groove bottom, and the temporary oil storage amount up to the drain hole 120 is expanded. Further, 24 upper slits 113 communicating from the inner peripheral side toward the outer periphery are arranged at equal intervals on the upper side circumference of the ring main body of the oil scraping ring 110 of the first embodiment, and are arranged on the lower side circumference. Considering not to be at the same position as the upper slit 113, 24 lower slits 114 communicating from the inner circumference side toward the outer circumference are provided at equal intervals.
Furthermore, in the first embodiment, the bottom surface of the ring groove bottom 180 of the stuffing box is inclined toward the lower outer periphery at an angle of 10 degrees, and the passing oil can be guided to the drain hole 120 without stagnation.

  Further, in the first embodiment, a drain hole opened in the axial direction at a position where the groove bottom 180 of the three-stage ring groove including the lowest stage of the oil scraping ring 110 attached to the stuffing box 80 is lowest. 120 communicated to the crankcase under the engine. In the first embodiment, 30 drain holes 120 are arranged on the same circumference of the ring groove bottom.

  The inventor incorporated the stuffing box of Example 1 into an engine that actually has an abnormal oil consumption, and conducted a comparative test with the prior art in order to confirm the effect. The conditions at that time are shown in Table 2, and the results are shown in Table 3 and FIG.

Table 2: Comparative test conditions between Example 1 and the prior art

Table 3: Verification test results of Example 1

In Table 2, the operating load should be understood as the throttle opening. The operating load of 75% is a relatively high load in the range of normal operation, and is a severe operating situation as a test. If the load is increased more than this, the pressure in the cylinder will increase too much and an accurate confirmation test will not be possible.
There were two abnormal cylinders (N1, N2) of the internal combustion engine used in this test, and the system oil was actually consumed in units of several tens of liters per day. This is an abnormal amount of consumption that is more than four times the normal amount, and even if it was replaced with a new conventional ring, it was not improved at all. In such a case, if the piston rod is partly worn in the past, the piston rod has been dealt with by extensive replacement work. However, as shown in Table 3 and FIG. 3, the oil consumption was dramatically improved in both of the two cylinders where the abnormality was confirmed by simply replacing the stuffing box of the present invention. The oil consumption has been further improved compared to the cylinders.
In addition, it can be confirmed from the wear state of the rail portion that the life of the ring can be extended by three times in the first embodiment, and it has been found that in any case, an excellent effect is exhibited in combination with drastically reducing oil consumption. did.
Furthermore, it can be confirmed from the graph of FIG. 3 that the oil consumption is less than that of the prior art from the beginning of the elapsed time. This proved that the initial familiarity of the oil scraping ring with increased flexibility attached to the stuffing box of the present invention acted more effectively from the beginning, and the familiarity increased with the passage of time.

  The embodiment described above is illustrative in all respects. The scope of the present invention is shown not by the above description but by the scope of the claims, and is intended to include all the techniques within the meaning and scope equivalent to the scope of the claims.

1 is a cross-sectional view showing a main part of Example 1. FIG. 2 is a cross-sectional view of an oil scraping ring main body of Example 1. FIG. The oil consumption confirmation test result of Example 1. It is sectional drawing of the conventional stuffing box.

Explanation of symbols

80 casing body 100 land 110 oil scraping ring 120 drain hole (discharged to the side)
170 drain hole (discharged to crankcase)
180 ring groove bottom 210 seal ring

Claims (6)

  In a stuffing box for piston rod of a crosshead type diesel engine, a seal ring is incorporated in each upper stage of a plurality of ring grooves formed in the casing, and an oil scraping ring is incorporated in each of the lower ring grooves. The ring body is divided into at least two in the circumferential direction, and the cross-sectional shape has an axial width of 5 mm or more and 15 mm or less, and a radial thickness including a separate rail portion of 17 mm or more and 23 mm or less. A stuffing box characterized by being.   The stuffing box according to claim 1, wherein the oil scraping ring is attached to at least one of the oil scraping rings including a lowermost step of a continuous ring groove.   The outer diameter of the ring groove bottom where the oil scraping ring is mounted is set to be approximately equal to the outer diameter of the groove bottom of the seal ring formed in the upper stage or set to be equal to or larger than the outer diameter of the groove bottom of the seal ring The stuffing box according to claim 1, wherein the stuffing box is characterized in that:   The stuffing box according to any one of claims 1 to 3, wherein a groove bottom lower side surface of a ring groove on which the oil scraping ring is mounted is inclined downward toward a radially outer side.   Two or more groove bottoms including at least the lowest stage of the ring groove for mounting the oil scraping ring are communicated to the crankcase below the engine through a drain hole that is opened in parallel with the center axis of the stuffing box. The stuffing box according to any one of claims 1 to 4, characterized in that:   6. The oil scraping ring main body according to any one of claims 1 to 5, wherein a plurality of slits that communicate in the radial direction from the inner peripheral surface toward the outer peripheral surface are provided on both or either one of the upper side surface and the lower side surface. The stuffing box described in the section.

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