JP2015209859A - Oil scrape ring for piston rod and stuffing box with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil scrape ring for a piston rod which is excellent in oil scrape performance and can reduce a drain amount, and a stuffing box with the oil scrape ring.SOLUTION: In an oil scrape ring, a ring body is divided in a circumferential direction into two or more pieces. The oil scrape ring includes one rail portion in an inner circumferential side and in axially central portion, an accommodation groove for a coil spring in an outer circumferential side and in axially central portion, and a plurality of oil passage grooves formed alternately in both an upper face and a lower face.

Description

  The present invention relates to an oil scraping ring for a piston rod, and more particularly to an oil scraping ring for a piston rod used in a large-sized two-cycle diesel engine for a ship and a stuffing box provided with the oil scraping ring.

  In general, large two-cycle diesel engines for ships are provided with a partition plate between the scavenging chamber and the crank chamber of the engine, and the piston rod accommodates an airtight ring or an oil scraping ring provided immediately above the partition plate. Reciprocates through the stuffing box. For example, in a general stuffing box 400 disclosed in Patent Document 1 as shown in FIG. 8, the outer periphery of the piston rod 300 is sealed by an airtight ring 100 and an oil scraper ring 110, and combustion residue from an engine scavenging chamber Has a sealing function that prevents the cylinder oil containing the oil from flowing into the crank chamber and an oil scraping function that scrapes off the system oil adhering to the piston rod 300 and returns it to the crank chamber.

  The conventional oil scraping ring 110 shown in FIG. 8 is composed of a combination of three divided ring bodies having two rail portions, and a coil spring 200 is arranged on the outer periphery and overlapped with the ring groove. Installed. The oil scraping ring 110 has its inner peripheral surface pressed against the outer peripheral surface of the piston rod 300 by the contraction force of the coil spring 200, and adheres to the piston rod surface and moves to the scavenging chamber when the piston rod 300 reciprocates. Scrape off system oil to prevent excessive consumption of system oil. In order to facilitate removal and discharge of the system oil that has been scraped off, an oil through hole 210 that is connected from the inner peripheral side to the outer peripheral side is generally provided between the two rail portions.

  In addition, a communication hole 401 is provided in the first ring groove from the top of the oil scraping ring groove, and the cylinder oil containing combustion residues from the engine scavenging chamber and the oil scraping ring 110 have entered without scraping. The mixed oil is discharged to the outside as a drain from this communication hole 401, and the system oil scraped off from the piston rod 300 is ringed through the oil through hole 210 of the oil scraper ring 110 into the second and lower ring grooves. It is collected at the groove bottom and returned to the crank chamber by a hole 402 provided on the outer periphery of the ring groove. In general, system oil is expensive compared to fuel and cylinder oil, and its consumption greatly affects the operating cost of ships. Specifically, the drain amount is reduced to reduce the consumption of system oil. There is a strong demand for that.

In order to improve the oil scraping function of the oil scraping ring, several improvements have been made so far. Patent Document 2 discloses a structure for achieving a reduction in oil consumption (drain amount) and a longer life as a small, light and flexible structure from the conventional oil scraping ring 510 shown in FIG. Disclosed is an oil scraping ring 610 having a cross-sectional shape with an axial width of 5 mm to 15 mm and a radial thickness of 17 mm to 23 mm, including a separate rail. In Patent Document 3, as shown in FIG. 10, the axial width (h ₁ ) is 5 mm or more and 10 mm or less, and the radial thickness (a ₁ ) is the rail portion. The ring main body 710 of 10 mm or more and 20 mm or less is divided into at least two in the circumferential direction, one rail portion 711 at the inner peripheral axial center and the coil spring at the outer axial central portion. And an oil scraping ring having a plurality of oil passage grooves 713 on only one side of the upper and lower side surfaces. There.

  The oil scraping rings of Patent Document 2 and Patent Document 3 are more effective in reducing the drain amount than the oil scraping rings before that. However, the reduction of the drain amount is an eternal problem, and the actual situation is that further reduction is required.

JP 60-18664 A JP 2008-261364 A JP 2011-12758 A

  In view of the above problems, an object of the present invention is to provide an oil scraping ring for a piston rod that is more excellent in oil scraping performance than before and can reduce the drain amount, and a stuffing box including the oil scraping ring.

  In order to further improve the followability of the oil scraping ring of Patent Document 3 and reduce the amount of drainage, the present inventors have intensively studied, and as a result, oil passage grooves are alternately formed on both the upper and lower sides of the oil scraping ring. It was conceived that an oil scraping ring that balances the upper and lower sides and has improved followability can be obtained by preparing for.

  That is, the piston rod oil scraping ring of the present invention includes a ring body having a rail portion that is in sliding contact with the outer peripheral surface of the piston rod that reciprocates, and an annular shape that presses and urges the rail portion against the outer peripheral surface of the piston rod. An oil scraping ring for a piston rod having a coil spring, wherein the ring main body is divided into at least two in the circumferential direction, one rail portion at the central portion in the axial direction on the inner peripheral side, and the axial direction on the outer peripheral side The coil spring receiving groove is provided in the central portion, and a plurality of oil passage grooves are provided alternately on the upper side surface and the lower side surface.

  The oil scraping ring for piston rod of the present invention is provided with oil passage grooves alternately on both the upper side surface and the lower side surface, thereby improving the followability by lowering the secondary moment while maintaining the balance between the upper and lower sides. Oil scraping ring by setting the inner circumferential side separation distance and the outer circumferential side separation distance in the direction perpendicular to the axis of the ring body between the oil passage groove on the lower side surface adjacent to the oil passage groove on the lower surface to a predetermined distance. Maintaining the necessary rigidity, it exhibits excellent oil scraping performance and contributes to the reduction of drainage. In addition, the oil passage groove is inclined so that the cross-sectional area increases from the inner circumference side to the outer circumference side, so that the oil that has entered the oil passage groove on the upper side can be easily removed and discharged. When multiple cylinders are mounted in a single ring groove, the size of the oil passage groove can be increased and oil can be discharged more easily by combining the oil passage grooves of the oil scraping rings adjacent to each other vertically. Will be able to.

It is sectional drawing which shows typically the stuffing box equipped with the oil scraping ring for piston rods of this invention. It is a figure which shows an example of the oil scraping ring for piston rods of this invention, (a) is the top view which looked at the oil scraping ring from the axial direction, (b) is the front view which looked at the ring from the radial direction outer peripheral side. Part (c) is an AA cross-sectional view of the ring. It is another example of the oil scraping ring for piston rods of this invention, and is sectional drawing in which the oil passage groove | channel inclined. It is another example which has a pin in the upper surface side of the oil scraping ring for piston rods of this invention, and is sectional drawing of the part which has a pin. It is another example which has a pin hole in the lower surface side of the oil scraping ring for piston rods of this invention, and is sectional drawing of the part which has a pin hole. FIG. 4 is an example of a cross-sectional view showing a state where the oil scraping ring is stacked in three stages and mounted in one ring groove in the stuffing box equipped with the piston rod oil scraping ring of the present invention. It is another example of sectional drawing which shows the state where the oil scraping ring was piled up in three steps and mounted in one ring groove in the stuffing box equipped with the piston rod oil scraping ring of the present invention. It is sectional drawing which shows typically the stuffing box equipped with the conventional oil scraping ring for piston rods. It is sectional drawing which showed the stuffing box which equipped with the oil scraping ring for piston rods of another form of another conventionally disclosed by patent document 2, (a) is a conventional type, (b) improves (a) Shown is a small, lightweight, flexible oil scraping ring. It is the figure which showed the conventional oil scraping ring for piston rods of another form disclosed by patent document 3, (a) is the top view which looked at the oil scraping ring from the axial direction, (b) is the ring of the ring It is BB sectional drawing.

  FIG. 1 schematically shows a cross-section of a stuffing box 10 equipped with an oil scraping ring 1 for a piston rod showing an embodiment of the present invention. The oil scraping ring 1 is stacked in three stages in each ring groove. Contained. The oil scraping ring 1 has one rail portion 2 slidably in contact with the outer peripheral surface of the piston rod 30 that reciprocates in the central portion in the axial direction on the inner peripheral side, and the rail portion 2 is located with respect to the outer peripheral surface of the piston rod 30. An annular coil spring 3 that is pressed and urged is provided in a coil spring housing groove 7 formed in the axially central portion on the outer peripheral side. FIG. 2 (a) is a plan view of the oil scraping ring 1 divided into three parts, showing the embodiment of the present invention, as viewed from the axial direction of the ring body, and FIG. (C) is a cross-sectional view taken along the line AA of the ring. The oil scraping ring 1 is provided with a plurality of oil passage grooves alternately on both sides of the upper side surface and the lower side surface, and the groove depth on the inner peripheral side is set so as not to reach the rail portion 2. The alternate formation of the oil passage groove 4 on both sides of the top and bottom sides contributes to both the improvement of the balance between the top and bottom and the improvement of follow-up by further lowering the moment of inertia of the cross section compared to the formation of only one side of the top and bottom sides. doing. Here, in order to maintain the rigidity required for the oil scraping ring while improving the followability, it is perpendicular to the axis of the ring body between the oil passage groove 4 on the upper side surface and the oil passage groove 4 on the lower side surface adjacent thereto. The inner circumferential side separation distance (t) and the outer circumferential side separation distance (t ′), that is, the distance between the portions not having the oil passage groove on the upper and lower side surfaces is preferably 2 mm or more (FIG. 2). (See (a)). The separation distance (t and t ') is more preferably 2.5 mm or more, and further preferably 3 mm or more. Furthermore, it is preferable that the inner peripheral opening area ratio of the oil passage groove 4 is 10 to 35%. More preferably, it is 15 to 30%, and further preferably 18 to 27%.

  The oil passage groove 4 is preferably inclined so as to increase the cross-sectional area from the inner periphery side to the outer periphery side, and the inclination angle θ of the oil passage groove 4 is in a direction perpendicular to the axis of the ring body. On the other hand, it is preferably 3 to 10 °, more preferably 5 to 8 °. FIG. 3 shows an inclined oil passage groove 4. This inclination makes it easier for the cylinder oil or the system oil that has entered the oil passage groove 4 to flow to the bottom side of the ring groove.

  In addition, as shown in FIG. 4, the piston rod oil scraping ring 1 of the present invention has a pin 8 for coupling with another piston rod oil scraping ring 1 adjacent to the upper side on the upper side of the ring body. As shown in FIG. 5, a pin hole 9 for coupling with a pin 8 of another piston rod oil scraping ring 1 adjacent to the lower side is provided on the lower side of the ring body as shown in FIG. It is preferable to have. It is preferable that a plurality of these piston rod oil scraping rings 1 be mounted in a single ring groove of the stuffing box 10 so that the oil passage grooves 4 of the adjacent piston rod oil scraping rings 1 face each other. It preferably includes a combination of piston rod oil scraping rings arranged. FIG. 6 shows the oil scraping rings stacked in three stages, in which the oil passage grooves 4 and 4 of the upper two stages of the oil scraping ring are opposed to each other, and the cross-sectional area of the oil passage groove is doubled (4 +4) Cylinder oil or system oil tends to flow into the oil passage groove. FIG. 7 is a cross-sectional view of the oil passage groove adjacent to the oil passage groove shown in the cross-sectional view shown in FIG. 6, and the oil passage grooves 4, 4 of the lower two-stage oil scraping ring face each other. It shows how they are arranged.

  The connecting part by the pin 8 and the pin hole 9 may be one place by combining three divided oil scraping rings. By providing clearance in the pin hole 9, the followability of each oil scraping ring to the piston rod 30 is maintained. can do. Generally, the oil scraping ring is inclined as the piston rod moves up and down due to the side clearance in the ring groove. When the rails of FIGS. 8 and 9 are two oil scraping rings 110, 510, and 610, a gap is formed between the rail on one side and the piston rod due to the inclination. In the oil scraping ring 1 of the present invention, one rail 2 is Because it is pressed and biased by one coil spring 3 and there is clearance in the pin hole 9, it can follow the piston rod 30 independently, and even if the oil scraping ring 1 is tilted, the rail 2 and piston Another feature is that a gap is hardly formed between the rods 30.

Example 1
As Example 1, for a 7-cylinder large two-cycle low-speed diesel engine with a bore diameter of 800 mm and a stroke of 2800 mm, an inner diameter of 310 mmφ, an outer diameter of 345 mmφ, a width (h1) of 8 mm, and a thickness including a rail (a1) An oil scraping ring body made of a lead bronze casting (CAC603) divided into three in the circumferential direction having a width of 17.5 mm, a width of the rail portion of 1.5 mm, and a thickness of the rail portion of 4.5 mm was manufactured. The ring body has oil passage grooves with a groove width of 30 mm and a groove depth of 2.5 mm alternately on the upper and lower sides, 5 on the upper side, 4 on the lower side, and 15 on the upper side of the entire ring. Twelve were formed on the lower surface. Here, the separation distance between the oil passage grooves was 5.37 mm on the inner circumferential side (t) and 7.64 mm on the outer circumferential side (t ′). The stuffing box has a structure with four ring grooves for mounting these oil scraping rings in two stages, and the oil scraping ring is mounted in two stages, so the lower oil scraping ring has an upper stage. A pin to be coupled with the pin hole of the oil scraping ring was attached, and a pin hole to be coupled with the pin of the lower oil scraping ring was formed in the upper oil scraping ring. Due to this connection, the oil passage grooves of the oil scraping rings adjacent to each other in the upper and lower sides are positioned to face each other. The coil spring (made by SWPB) combined with these oil scraping rings was adjusted so that the surface pressure was 0.24 MPa.

Comparative Example 1
As Comparative Example 1, the shape of the oil scraping ring 510 shown in FIG. 9 (a) has an inner diameter of 310 mmφ, an outer diameter of 358 mmφ, a width (h1) of 22 mm, a thickness including the rail (a1) of 26.5 mm, a rail An oil scraping ring body made of conventional cast iron (FC250) with a width of 1.5 mm and a rail thickness of 4.5 mm divided in three circumferential directions was produced. Here, the coil spring (manufactured by SWPB) was adjusted so that the surface pressure was 0.38 MPa.

[1] Actual machine test 1
Compared to 7 cylinders, the stuffing box A equipped with the oil scraping ring of Example 1 was compared with a 7-cylinder tank for carrying out actual machine tests on a tanker equipped with a 7-cylinder large 2-cycle low-speed diesel engine with a bore diameter of 800 mm and a stroke of 2800 mm. Seven cylinders of stuffing box B equipped with the oil scraping ring of Example 1 were prepared. The actual machine test was started using stuffing box B for all seven cylinders. After 1008 hours, stuffing box B was replaced with stuffing box A, and another 1008 hours were conducted. Table 1 shows the relative amount of drain (l / day) for 24 hours, 504 hours, and 1008 hours for each cylinder, and the drain amount (l / day) for the first cylinder of Comparative Example 1 after 24 hours. Shown in quantity.

 The initial drain amount (24 hours) of Example 1 was 20.9% compared to the initial drain amount of Comparative Example 1, and was greatly reduced (79.1%) by using the oil scraping ring of the present invention. Further, the drain amount hardly changed even after 1008 hours had passed.

Example 2
As Example 2, for a three-cylinder large two-cycle low-speed diesel engine with a bore diameter of 370 mm and a stroke of 880 mm, an inner diameter of 138 mmφ, an outer diameter of 165 mmφ, a width (h1) of 6 mm, and a thickness not including the rail (a1 ) An oil scraping ring body made of lead bronze casting (CAC603) divided into 3 parts in the circumferential direction with 9 mm, rail width 1.5 mm and rail thickness 4.5 mm was prepared. Here, the ring body has oil passage grooves with a groove width of 13 mm, an inner groove depth of 1.5 mm, and an inclination angle of 8 °, alternately on the upper and lower sides, 5 on the upper side and 4 on the lower side. In total, 15 rings were formed on the upper side and 12 on the lower side. Here, the separation distance between the oil passage grooves was 2.38 mm on the inner circumferential side (t) and 3.85 mm on the outer circumferential side (t ′). The stuffing box has a structure with four ring grooves for mounting these oil scraping rings in three stages, and since the oil scraping ring is mounted in three stages, it is attached to the upper side of the lower oil scraping ring. Attach a pin to be coupled with the pin hole of the middle oil scraping ring, and form a pin hole to be coupled with the pin of the lower oil scraping ring on the lower surface and upper surface of the middle oil scraping ring, respectively. A pin to be connected to the pin hole of the scraping ring was attached, and a pin hole to be connected to the pin of the middle oil scraping ring was formed on the lower surface of the upper oil scraping ring. By this connection, the upper and lower middle and lower and upper oil scraping rings of the oil scraping ring adjacent to each other are positioned so as to face each other. In addition, the coil spring (manufactured by SWPB) combined with these oil scraping rings was adjusted so that the surface pressure was 0.13 MPa.

Comparative Example 2
As a comparative example 2, the shape of the oil scraping ring 110 having two rail portions shown in FIG. 8 is shown. The inner diameter is 138 mmφ, the outer diameter is 169 mmφ, the width (h1) is 9 mm, and the thickness including the rail portion (a1) is 15.5. An oil scraping ring body made of conventional cast iron (FC250) divided into three in the circumferential direction with a width of 1.5 mm, a rail width of 1.5 mm, and a rail thickness of 5.0 mm was produced. Here, the coil spring (manufactured by SWPB) was adjusted so that the surface pressure was 0.13 MPa.

[2] Actual machine test 2
Compared to the three-cylinder stuffing box C equipped with the oil scraping ring of Example 2 to test the actual machine on a ship equipped with a 3-cylinder large 2-cycle low-speed diesel engine with a bore diameter of 370 mm and a stroke of 880 mm Three stuffing boxes D equipped with the oil scraping ring of Example 2 were prepared. The actual machine test was started using stuffing box D for all three cylinders. After 1008 hours, stuffing box D was replaced with stuffing box C, and another 1008 hours were conducted. Table 2 shows the relative amount of drainage (l / day) for 24 hours, 504 hours, and 1008 hours for each cylinder, and the drainage amount (l / day) for the first cylinder of Comparative Example 2 after 24 hours. Shown in quantity.

  The initial drain amount (24 hours) of Example 2 was 3.2% compared to the initial drain amount of Comparative Example 2, and was significantly reduced (96.8%) by using the oil scraping ring of the present invention. Further, the drain amount hardly changed even after 1008 hours had passed.

1, 110, 510, 610, 710 Oil scraping ring
2, 711 Rail section
3, 200 coil spring
4, 210, 713 Oil through groove
5, 401 communication hole
6, 402 holes
7, 712 Coil spring receiving groove
8 pin
9 Pin hole
10, 400 stuffing box
30, 300 Piston rod

Claims (9)

  An oil scraping ring for a piston rod having a ring body having a rail portion slidably contacting an outer peripheral surface of a piston rod that reciprocates, and an annular coil spring that presses and urges the rail portion against the outer peripheral surface of the piston rod. The ring body is divided into at least two in the circumferential direction, one rail portion at the inner axial side central portion, an accommodation groove for the coil spring at the outer axial side central portion, and an upper side surface And an oil scraping ring for a piston rod, wherein a plurality of oil passage grooves are alternately provided on both sides of the lower surface.   2. The piston rod oil scraping ring according to claim 1, wherein a separation distance on an inner peripheral side in a direction perpendicular to the axis of the ring main body between the oil passage groove on the upper side surface and the oil passage groove on the lower side surface adjacent to the oil passage groove on the upper side surface. An oil scraping ring for a piston rod, wherein (t) and the outer peripheral side separation distance (t ′) are both 2 mm or more.   The oil scraping ring for piston rod according to claim 1 or 2, wherein the oil perforation groove has an inner peripheral opening area ratio of 10 to 35%.   The oil scraping ring for piston rod according to any one of claims 1 to 3, wherein the oil passage groove is inclined so as to increase the cross-sectional area from the inner peripheral side to the outer peripheral side. Oil scraping ring.   5. The piston rod oil scraping ring according to claim 4, wherein an angle of inclination of the oil passage groove is 3 to 10 degrees with respect to a direction perpendicular to the axis of the ring body. .   The piston rod oil scraping ring according to any one of claims 1 to 5, wherein the upper surface of the ring body has a pin for coupling with another piston rod oil scraping ring adjacent to the upper side. An oil scraping ring for piston rods.   The piston rod oil scraping ring according to claim 1, wherein the lower surface of the ring main body has a pin hole for coupling with another piston rod oil scraping ring adjacent to the lower side. An oil scraping ring for piston rods.   A stuffing box, wherein a plurality of piston rod oil scraping rings according to claim 6 are stacked in a single ring groove.   9. The stuffing box according to claim 8, comprising a combination of piston rod oil scraping rings in which the oil through grooves of the adjacent piston rod oil scraping rings are arranged to face each other. .

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