JP6849891B2 - Piston pump rod packing - Google Patents

Description

The present invention is suitable for use, for example, when an extremely low temperature liquid having an extremely low boiling point such as liquefied natural gas is sucked into a cylinder liner by a piston, discharged at a high pressure by the piston, and supplied to a supplied body. Regarding the rod packing of the piston pump.

Traditionally, diesel engines that use liquefied natural gas as fuel have been used in vehicles and the like. However, in recent years, in low-speed diesel engines that use heavy oil-based fuels, high-pressure natural gas is injected into the cylinder of the engine and burned in order to reduce emissions of NOX, SOX, etc. and improve emission environmental performance. Development of a high-pressure gas injection type low-speed 2-cycle diesel engine is underway. The high-pressure gas injection type low-speed two-cycle diesel engine is a relatively large diesel engine, and is generally used for ships and the like.

On the other hand, in ships and the like, it is necessary to be able to arrange the liquefied gas supply device in the gas dangerous area, and for this reason, the development of a liquefied gas supply device having excellent safety is being promoted (for example, Patent Document 1). reference). In this liquefied gas supply device, a piston pump is used as a booster device for boosting and discharging low-temperature liquefied natural gas to a desired pressure and supplying the high-pressure liquefied natural gas to a heating device that heats and vaporizes it. Will be done.

This conventional piston pump has the following configuration, for example, as shown in FIG. 7 (see, for example, Patent Document 1). Cylinder liner 103 in the cylinder 102 of the piston pump 101, cylinder head chamber 104, piston 105 inserted in the cylinder liner 103, valve head 106 arranged in the cylinder head chamber 104, cylinder head 107 attached to the cylinder 102. Is arranged.

The cylinder head chamber 104 is provided in the cylinder 102 between the cylinder liner 103 and the cylinder head 107. The piston 105 reciprocates in the cylinder liner 103 via a motion conversion mechanism such as a crank mechanism, a piston rod 112 attached to the base of the piston 105, and the like, using a hydraulic pump or the like controlled by a controller (not shown) as a drive source. Move. The cylinder 102 has a liquid fuel supply port 108, and low-temperature liquid fuel is guided into the cylinder head chamber 104 at a relatively low pressure through the supply port 108.

The liquid fuel pressurized from the piston 105 is discharged to the outside at high pressure through the discharge port 109. A discharge path 110 communicating with the discharge port 109 is bored in the cylinder head 107 in the axial direction. The cylinder liner 103 has a valve accommodating chamber 113 on the valve head 106 side, and in the valve accommodating chamber 113, a suction including a valve plate (not shown) and a pressure spring (not shown) for urging the valve plate toward the valve head 106. A valve is arranged. A plurality of piston ring grooves 118 are formed on the outer peripheral portion of the piston 105, and a piston ring 119 is attached to each piston ring groove 118.

On the other hand, the liquid fuel leaking from between the cylinder 102 and the cylinder liner 103 is returned to the liquid fuel supply side via the discharge ports 128 and 129, respectively. The piston rod 112 is liquid-tightened with the cylinder 102 by a seal portion 121 composed of a plurality of packing portions arranged in the cylinder 102, and is communicated with the piston rod 112 through the discharge port 129 or the like. The liquid fuel on the side is prevented from leaking to the outside from between the cylinder 102 and the piston rod 112. Further, nitrogen gas is supplied to the seal portion 121 from the outside and pressurized, so that the liquid fuel does not leak to the outside from between the cylinder 102 and the piston rod 112.

As shown in FIG. 8, the rod packings 122 and 123 constituting the above-mentioned packing portion are divided into three in the circumferential direction and have three tangential division portions, and three tangential division type ring segments 124 and FIG. 9 show. As shown, it is composed of three spiral ring segments 125 having a split portion in the spiral direction, and these rod packings 122 and 123 are assembled in layers, for example, two in the axial direction to form one packing portion. A plurality of packing portions are arranged in the axial direction to form the seal portion 121 described above.

Each of the ring segments 124 and 125 of the rod packings 122 and 123 is urged toward the piston rod 112 by a tension spring (not shown) attached to the outer peripheral portion, and is pressed against the piston rod 112, respectively. The ring segments 124 and 125 are also pressed by the differential pressure applied between the rod packings 122 and 123 assembled in layers.

Therefore, the rod packings 122 and 123 are usually formed of a relatively flexible material, and are deformed along the outer peripheral portion of the piston rod 112 by the above-mentioned pressing force to form the cylinder 102 and the piston rod 112. Make the space liquidtight.

Japanese Patent No. 5934409

As described above, the rod packings 122 and 123 constituting each packing portion of the conventional seal portion 121 are divided into three in the circumferential direction and have three divided portions in the tangential direction, as shown in FIG. 8, for example. It is composed of a tangential split type ring segment 124, three swirl type ring segments 125 having a swirl direction split portion, and the like as shown in FIG. 9, and rod packings 122 and 123 are provided in the axial direction, for example, two by two. It is assembled in layers to form one packing portion, and a plurality of these packing portions are arranged in the axial direction to form the above-mentioned sealing portion 121.

Further, the ring segments 124 and 125 are respectively urged toward the piston rod 112 by a tension spring attached to the outer peripheral portion, pressed by the piston rod 112, and between the ring segments 124 and 125 assembled in a layered manner. It is also pressed by the differential pressure applied to the piston rod 112 and deforms along the outer peripheral portion of the piston rod 112 to make the space between the cylinder 102 and the piston rod 112 liquid-tight.

On the other hand, for example, in the case of a piston pump used for pressurizing an extremely low temperature liquid, in order to maintain good slidability even without lubrication, for example, a fluororesin composite material is used as the material of the rod packing. Is often used. This fluororesin composite material has a coefficient of thermal expansion of about 10 times that of a metal material, is easily affected by temperature changes, and has an extremely high rigidity under extremely low temperature conditions and is less likely to be deformed.

Therefore, in the piston pump for pressurizing the ultra-low temperature liquid, the ring segments 124 and 125 of the rod packings 122 and 123 contract significantly due to the temperature drop due to the operation, and the shape does not follow the outer shape of the piston rod 112. At the same time, it becomes extremely hard and hard to be deformed. Therefore, under extremely low temperatures, the ring segments 124 and 125 of the rod packings 122 and 123 do not follow the outer peripheral portion of the piston rod 112, and liquid (including vaporized ones) flows between the cylinder 102 and the piston rod 112. There is a problem of leaking.

As a countermeasure against this problem, the number of divisions in the circumferential direction of the rod packing is increased, for example, to 6 divisions, which is twice the conventional number, to ensure the flexibility of the entire rod packing at extremely low temperatures, thereby ensuring the flexibility of the rod packing. It is also conceivable to make the piston rod along the outer peripheral portion. However, the solution of increasing the number of divisions of the rod packing in the circumferential direction complicates the structure of the rod packing, makes the manufacturing itself difficult, and even if the manufacturing becomes possible, the manufacturing cost is high. There is a problem that it will increase significantly.

The present invention has been made to solve such a problem, is easy to manufacture, does not cause a significant increase in manufacturing cost, and is a liquid between the cylinder and the piston rod even if there is a large temperature drop. It is an object of the present invention to provide a rod packing of a piston pump capable of preventing leakage of gas or gas.

In order to solve the above-mentioned problems, the rod packing of the piston pump of the present invention is connected to a cylinder having a cylinder liner inside, a piston reciprocally inserted into the cylinder liner, and inside the cylinder. A piston rod that is inserted into the cylinder liner to reciprocate the piston in the cylinder liner, a seal portion that is arranged between the piston rod and the cylinder to make the piston rod and the cylinder liquid-tight or airtight, and a seal portion. An annular rod packing that is arranged so that the inner peripheral portion is formed along the outer peripheral portion of the piston rod, and an urging means that urges the rod packing toward the piston rod side and presses the rod packing against the piston rod. It is a rod packing of a piston pump provided, and the rod packing is provided with an opening at the inner peripheral portion and further provided with a slit extending to the outer peripheral portion side.

As described above, the rod packing of the piston pump of the present invention has an opening in the inner peripheral portion and a slit extending to the outer peripheral portion side, so that the rod packing does not follow the outer peripheral portion of the piston rod due to a large temperature drop. Even if the shape changes or the material hardens, the flexibility of the entire rod packing is ensured by the action that is very close to that when the rod packing is formed in multiple parts, and the rod packing is pistoned by the urging force of the urging means. It deforms along the outer circumference of the rod and adheres well. Therefore, liquid or gas is prevented from leaking from between the cylinder and the piston rod. Slit processing is easy and does not lead to an increase in manufacturing cost.

In the rod packing of the piston pump, it is desirable that the rod packing is composed of a plurality of ring segments connected in the circumferential direction, and the slit is formed in the ring segments.

As described above, the rod packing is composed of a plurality of ring segments which are continuously provided in the circumferential direction, and the slits are formed in the ring segments, so that the flexibility is increased only by dividing the rod packing. In addition, the flexibility of the ring segment increases due to the formation of the slit, and even if the shape of the rod packing changes or the material hardens due to a large temperature drop, the rod packing adheres better to the outer periphery of the piston rod. , Liquids and gases are further prevented from leaking between the cylinder and the piston rod.

In the rod packing of the piston pump, it is desirable that the ring segment has a slit opening at the central portion in the circumferential direction of the inner peripheral portion. As described above, since the ring segment has the opening of the slit in the central portion in the circumferential direction of the inner peripheral portion, the flexibility of the ring segment at a large temperature decrease is uniformly increased in the circumferential direction.

In the rod packing of the piston pump, a plurality of the rod packings are arranged so as to be coaxially overlapped in a layer in the axial direction, and the slits of the adjacent rod packings of the plurality of the overlapped rod packings are arranged. It is desirable that they are arranged so as to be offset from each other in the circumferential direction.

In this way, the slits of the adjacent rod packings of the plurality of stacked rod packings are arranged so as to be displaced from each other in the circumferential direction, thereby preventing liquid or gas from leaking through the slits. Slit.

In the rod packing of the piston pump, the slit extends from the inner peripheral portion to the outer peripheral portion side to a region corresponding to a length of 40% to 70% of the radial length from the inner peripheral portion to the outer peripheral portion of the rod packing. It is desirable to have. As described above, the slit extends from the inner peripheral portion to the outer peripheral portion side to a region corresponding to a length of 40% to 70% of the radial length from the inner peripheral portion to the outer peripheral portion of the rod packing. , It is possible to optimally increase the flexibility of the rod packing with respect to a large temperature drop.

That is, when the slit extends from the inner peripheral portion to the outer peripheral portion side only to a region corresponding to a length of less than 40% of the radial length from the inner peripheral portion to the outer peripheral portion of the rod packing, the temperature is large. While the flexibility of the rod packing may not be sufficiently increased with respect to the reduction, the slit extends to a region corresponding to a length exceeding 70% of the radial length from the inner peripheral portion to the outer peripheral portion of the rod packing. If it extends from the inner peripheral portion to the outer peripheral portion side, there is a concern that the strength of the rod packing may decrease. From the above viewpoint, the slit extends from the inner peripheral portion to the outer peripheral portion side to a region corresponding to a length of 50% to 60% of the radial length from the inner peripheral portion to the outer peripheral portion of the rod packing. It is even more desirable to be there.

In the rod packing of the piston pump, it is desirable that the slit extends linearly from the inner peripheral portion to the outer side in the radial direction. As described above, since the slit extends linearly from the inner peripheral portion to the outer side in the radial direction, the flexibility of the rod packing with respect to a large temperature decrease is best achieved. Slit processing becomes even easier.

The rod packing of the piston pump of the present invention includes a cylinder having a cylinder liner inside, a piston reciprocally inserted in the cylinder liner, and a piston connected to the piston and inserted into the cylinder to insert the piston into the cylinder liner. A piston rod that reciprocates with a piston rod, a seal portion that is arranged between the piston rod and the cylinder to make the piston rod and the cylinder liquid-tight or airtight, and a seal portion that is arranged in the seal portion and has an inner peripheral portion that is a piston. It is a rod packing of a piston pump provided with an annular rod packing formed along the outer peripheral portion of the rod and an urging means for urging the rod packing toward the piston rod side and pressing the rod packing against the piston rod. The rod packing has an opening on the inner peripheral portion and further includes a slit extending toward the outer peripheral portion.

Therefore, the rod packing of the piston pump of the present invention is easy to manufacture, and liquid or gas leaks from between the cylinder and the piston rod even if there is a large temperature drop without causing a significant increase in manufacturing cost. It has the excellent effect of being able to prevent this.

It is an axial sectional view which shows the rod packing of the piston pump which concerns on this invention. It is an axial sectional view which shows the detail of the seal part of FIG. It is a front view which shows the tangential division type ring segment. It is a front view which shows the spiral split type ring segment. It is a perspective view which shows the tension spring of the rod packing of FIG. It is a partial front view which shows the slit of the ring segment of FIG. 3 and FIG. It is an axial sectional view which shows the rod packing of the conventional piston pump. It is a front view which shows the conventional tangential division type ring segment. It is a front view which shows the conventional spiral split type ring segment.

A mode for carrying out the piston pump according to the present invention will be described in detail with reference to FIGS. 1 to 6. FIG. 1 shows a piston pump 1 as an example, which is used for, for example, a ship, and liquefies a high-pressure gas injection type low-speed two-cycle diesel engine that injects and burns high-pressure liquefied natural gas. Used for gas supply equipment. The piston pump 1 boosts and discharges the supplied ultra-low temperature liquefied natural gas to a desired pressure, and supplies the liquefied gas to a heating device for heating and vaporizing the liquefied gas.

The piston pump 1 includes a cylinder 2 having a cylinder liner 3 disposed therein, a piston 5 inserted into the cylinder liner 3 so as to be reciprocally reciprocating in a liquid-tight and airtight manner, and a liquid-tight and airtight tip portion of the cylinder 2. A cylinder head 7 that is airtightly attached, a cylinder head chamber 4 that is a cavity defined between the cylinder liner 3 and the cylinder head 7 in the cylinder 2, and a valve head 6 that is arranged in the cylinder head chamber 4. And four suction passages 17 which are bored in the valve head 6 and communicate the cylinder head chamber 4 and the inside of the cylinder liner 3 are arranged. The four suction passages 17 are arranged at approximately 90 ° intervals in the circumferential direction of the valve head 6.

The cylinder head chamber 4 is provided in the cylinder 2 between the cylinder liner 3 and the cylinder head 7 so as to communicate with each other over 360 ° in the circumferential direction. The piston 5 uses a hydraulic pump or the like controlled by a controller (not shown) as a drive source, a motion conversion mechanism such as a crank mechanism, and a piston rod 12 which is connected to the piston 5 and is reciprocally inserted into the cylinder 2. It reciprocates in the cylinder liner 3 via the cylinder liner 3. The cylinder 2 has a liquid fuel supply port 8, and extremely low temperature liquid fuel is supplied into the cylinder head chamber 4 at a relatively low pressure through the supply port 8.

The liquid fuel pressurized by the piston 5 is discharged to the outside at high pressure through the discharge port 9 of the cylinder head 7. A discharge path 10 communicating with the discharge port 9 is bored in the cylinder head 7 in the axial direction. The cylinder liner 3 has a valve accommodating chamber 13 on the valve head 6 side, and in the valve accommodating chamber 13, a valve plate (not shown) and a pressure spring (not shown) for urging the valve plate toward the valve head 6 A suction valve is provided.

A plurality of piston ring grooves 18 are formed on the outer peripheral portion of the piston 5, and a piston ring 19 is attached to each piston ring groove 18. Further, the tip portion of the piston 5 has a protrusion 16 which is formed to have a diameter smaller than that of the piston 5 and projects toward the valve head 6.

On the other hand, the liquid fuel leaking from between the cylinder 2 and the cylinder liner 3 is returned to the supply side of the liquid fuel via the discharge ports 28 and 29, respectively. The piston rod 12 is liquid-tight and airtight with the cylinder 2 by a seal portion 30 arranged in the cylinder 2, and the liquid fuel on the supply side communicates with the piston rod 12 through, for example, the discharge port 29 described above. However, it is prevented from leaking to the outside from between the cylinder 2 and the piston rod 12.

Further, nitrogen gas is supplied from the outside to the seal portion 30 via the nitrogen gas supply path 33 bored in the thin lidar 2, and is pressurized, which also causes liquid fuel from between the cylinder 2 and the piston rod 12. Is prevented from leaking to the outside.

In the piston pump 1, the suction valve in the valve accommodating chamber 13 opens the outlet of the suction passage 17 during the suction stroke of the piston 5 and closes the outlet of the suction passage 17 during the compression stroke of the piston 5. The discharge valve 11 closes the discharge path 10 provided in the cylinder head 7 during the suction stroke of the piston 5, and opens the discharge path 10 during the compression stroke of the piston 5.

The valve head 6 is provided with an outlet opening 21 that communicates from the end surface on the cylinder liner 3 side to the discharge path 10 of the cylinder head 7, and the discharge valve 11 is arranged below the discharge path 10 of the cylinder head 7. .. While the discharge valve 11 has a plurality of inflow holes on the outer peripheral portion, the inflow hole is not formed at the tip portion on the cylinder liner 3 side, so that the tip portion is the outlet of the valve head 6 due to the urging force of the internal spring. The valve can be closed by contacting the end surface on the cylinder head 7 side in the vicinity of the opening 21.

When the piston 5 begins to extend toward the valve head 6 during the compression stroke, the discharge valve 11 opens against the urging force of the internal spring due to the pressure of the liquid fuel from the cylinder liner 3 side. Further, in the discharge valve 11, when the piston 5 is maximally extended, the protrusion 16 of the piston 5 penetrates the outlet opening 21 of the valve head 6, so that the pressure of the liquid fuel supplied from the outlet opening 21 side drops sharply. To do. As a result, the discharge valve 11 abuts on the end face on the cylinder head 7 side in the vicinity of the outlet opening 21 of the valve head 6 by the urging force of the internal spring, and closes the valve again.

In this way, a seal portion 30 that makes the space between the piston rod 12 and the cylinder 2 liquid-tight and airtight is arranged between the piston rod 12 and the cylinder 2. The seal portion 30 is urged toward the anti-piston 5 side in the axial direction by the coil spring 32 via the retainer 31 and is fixed in the cylinder 2.

As shown in FIG. 2, the seal portions 30 are, for example, six annular packing portions 35 which are arranged in layers in the axial direction and whose inner peripheral portions are formed along the outer peripheral portion of the piston rod 12. ~ 40 and two spacers 41 and 42.

In each packing portion 35 to 40, two (plurality) rod packings 45 and 46 shown in FIGS. 3 and 4 are combined, and these rod packings 45 and 46 are coaxially overlapped in a layer in the axial direction. Is formed. The rod packings 45 and 46 are, for example, flat in the radial direction and formed in an annular shape so that the piston rod 12 can be inserted into the inner peripheral portion, and are formed of a flexible fluororesin composite material. Will be done.

As shown in FIG. 2, for example, in the packing portion 35 which is arranged on the piston 5 side most, two flat plate-shaped rod packings 45 and 46 are arranged so as to be coaxially overlapped in a layer in the axial direction. The rod packings 45 and 46 are housed in a packing holder 52 having an L-shaped axial cross section. The arrangement of the two rod packings 45 and 46 may have a left-right positional relationship opposite to that shown in the figure.

As shown in FIGS. 3 and 4, the rod packings 45 and 46 have three (plurality) tangential split ring segments 47 and spiral split ring segments having a shape in which the entire circumference is substantially evenly divided into three. Formed from 48 respectively. The tangential split type ring segment 47 has a split portion formed in the tangential direction, and the spiral split type ring segment 48 has a spiral split portion formed.

As shown in FIG. 5, for example, the three ring segments 48 of the rod packing 46 have a tension spring 51 (attached) having a substantially circular cross-sectional shape and an annular shape as a whole in a spring groove 48c recessed in the outer peripheral portion 48b. The force means) is wound and integrated, whereby the rod packing 46 is formed. Due to the urging force of the tension spring 51, each ring segment 48 is pressed against the outer peripheral portion of the piston rod 12 and comes into close contact with each other. Since the same applies to the rod packing 45, the description thereof will be omitted.

As a result, the space between the cylinder 2 and the piston rod 12 is made liquidtight and airtight. The same applies to the other packing portions 36 to 40 shown in FIG. 2, which are formed by the combination of the two rod packings 45 and 46 described above.

However, for the packing portion 38, for example, in order to press these two rod packings 45 and 46 in the axial direction, the third packing 53 whose axial cross-sectional shape is formed in a tapered shape toward the center is a shaft. It is mounted so as to be overlapped in the direction and coaxially with the rod packings 45 and 46 in a layered manner.

In this case, the axial cross-sectional shape of the rod packings 45 and 46 adjacent to the packing 53 is flat as described above, but is formed so that a part of the rod packings 45 and 46 has a reverse taper in accordance with the taper of the packing 53. Will be done. The inner peripheral portion of the packing 53 is not in close contact with the outer peripheral portion of the piston rod 12, and the packing 53 is not directly liquid-tight and airtight between the cylinder 2 and the piston rod 12. The same applies to the packing portions 39 and 40.

As shown in FIGS. 3 and 4, each ring segment 47, 48 of the rod packings 45, 46 has slits 49, 50, respectively. The slits 49, 50 have openings 49a, 50a at the center of the inner peripheral portions 47a, 48a of the ring segments 47, 48 in the circumferential direction, and the slits 49, 50 have openings 49a, 50a toward the outer peripheral portions 47b, 48b of the ring segments 47, 48. Moreover, they extend linearly outward in the radial direction from their inner peripheral portions 47a and 48a.

As shown in FIG. 6, these slits 49, 50 are 40 having a radial length L0 from the inner peripheral portions 47a, 48a of the ring segments 47, 48 of the rod packings 45, 46 to the outer peripheral portions 47b, 48b. It is formed to a length L1 of% to 70%. That is, the slits 49 and 50 have an inner circumference up to a region corresponding to a length of 40% to 70% of the radial length L0 from the inner peripheral portions 47a and 48a of the ring segments 47 and 48 to the outer peripheral portions 47b and 48b. It extends from the portions 47a and 48a to the outer peripheral portions 47b and 48b.

The slits 49, 50 are limited to a region corresponding to less than 40% of the radial length L0 from the inner peripheral portions 47a, 48a of the ring segments 47, 48 of the rod packings 45, 46 to the outer peripheral portions 47b, 48b. If the rod packings 45 and 46 do not extend from the inner peripheral portions 47a and 48a to the outer peripheral portions 47b and 48b, the flexibility of the rod packings 45 and 46 at extremely low temperatures, which will be described later, may not be sufficiently increased.

On the other hand, the slits 49 and 50 correspond to a length exceeding 70% of the radial length L0 from the inner peripheral portions 47a and 48a of the ring segments 47 and 48 of the rod packings 45 and 46 to the outer peripheral portions 47b and 48b. When the ring segments 47a and 48a extend from the inner peripheral portions 47a and 48a to the outer peripheral portions 47b and 48b, there is a concern that the strength of the ring segments 47 and 48 themselves may decrease.

From the above viewpoint, the slits 49 and 50 have a length of 50% to 60% of the radial length L0 from the inner peripheral portions 47a and 48a of the ring segments 47 and 48 of the rod packings 45 and 46 to the outer peripheral portions 47b and 48b. It is desirable that the inner peripheral portions 47a and 48a extend toward the outer peripheral portions 47b and 48b to the region corresponding to the slit. The slits 49 and 50 may be formed by, for example, water jet processing, and the widths 49a and 50a of the openings may be narrow.

In the packing portions 35 to 40 shown in FIG. 2, the slits 49, 50 formed in the adjacent rod packings 45, 46 of the two rod packings 45, 46 coaxially overlapped in a layer in the axial direction are mutually connected. They are arranged so as not to overlap with each other by being shifted by a predetermined angle in the circumferential direction.

As shown in comparison with FIGS. 3 and 4, for example, in the packing portion 35 of the piston pump 1, the slits 49 of the two rod packings 45, 46 stacked in a layered manner and the adjacent rod packings 45, 46, The 50s are arranged so as to be offset by the maximum angle in the rod packings 45 and 46 composed of the ring segments 47 and 48 which are substantially evenly divided into three by about 120 ° in the circumferential direction. , Liquid fuel is surely prevented from leaking through the slits 49 and 50. The same applies to the other packing portions 36 to 40 shown in FIG.

As shown in FIG. 2, the two spacers 41 and 42 arranged so as to sandwich the packing portion 39 from both sides in the axial direction include an annular passage 41a and 42a formed on the outer peripheral portion and the annular passage 41a and 42a thereof. A plurality of pressurized passages 41b, 42b formed from the roads 41a, 42a toward the inner peripheral portion are arranged.

Nitrogen gas is supplied through the nitrogen gas supply path 33 of the cylinder 2 and the annular passages 41a and 42a and the pressurization passages 41b and 42b of the two spacers 41 and 42. As a result, the packing portions 35 to 39 arranged on the piston 5 side of the spacers 41 and 42 are pressurized by nitrogen gas to prevent the liquid fuel from leaking from the seal portion 30 to the outside. ..

As described above, the rod packings 45 and 46 of the piston pump 1 have openings 49a and 50a in the inner peripheral portions 47a and 48a and also have slits 49 and 50 extending toward the outer peripheral portions 47b and 48b. Even if the rod packings 45 and 46 are used for pressurizing low-temperature liquid fuel and cause shape changes and material hardening, the rod packings 45 and 46 have an action very similar to that when the rod packings 45 and 46 are formed in multiple divisions. The overall flexibility is increased.

Therefore, the rod packings 45 and 46 are deformed along the outer peripheral portion of the piston rod 12 by applying the urging force of the tension spring 51 so as to be in good contact with each other, and between the cylinder 2 and the piston rod 12. The liquid fuel is prevented from leaking from. The slits 49 and 50 are easy to process and do not lead to an increase in manufacturing cost.

Further, the rod packings 45 and 46 are formed of three ring segments 47 and 48 which are continuously provided in the circumferential direction, and slits 49 and 50 are formed in these ring segments 47 and 48 to form a rod. Not only the flexibility at extremely low temperature increases due to the division of the packings 45 and 46, but also the flexibility at extremely low temperature increases for each of the ring segments 47 and 48.

Therefore, the rod packings 45 and 46 are in close contact with the outer peripheral portion of the piston rod 12 even when the temperature is extremely low, and the liquid fuel is prevented from leaking from between the cylinder 2 and the piston rod 12.

Further, since the ring segments 47 and 48 have the openings 49a and 50a of the slits 49 and 50 in the central portion in the circumferential direction of the inner peripheral portions 47a and 48a, the ring segments 47 and 48 are flexible at an extremely low temperature. The property is uniformly increased in the circumferential direction of the entire ring segments 47, 48.

Further, the slits 49 and 50 extend linearly outward in the radial direction from the inner peripheral portions 47a and 48a of the ring segments 47 and 48 of the rod packings 45 and 46, so that the rod packings 45 and 46 are flexible at an extremely low temperature. The increase in sex is best achieved. In addition, the processing of slits becomes easier.

The rod packings 45 and 46 of the piston pump 1 described above are merely examples, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

For example, the slits 49 and 50 do not necessarily have to be formed in all the ring segments 47 and 48 forming the rod packings 45 and 46, but may be a part thereof. Further, the openings 49a and 50a of the slits 49 and 50 are not necessarily limited to those arranged at the central portion in the circumferential direction of the inner peripheral portions 47a and 48a of the ring segments 47 and 48. Further, the slits 49 and 50 are not necessarily limited to those extending outward in the radial direction from the inner peripheral portions 47a and 48a of the ring segments 47 and 48 and those extending linearly.

Further, there are various types of rod packings having a split portion having a shape other than the above-mentioned tangential split type ring segment 47 and the spiral split type ring segment 48, and the above-mentioned rod packings 45 and 46 may be formed by them. Of course. Further, the rod packings 45 and 46 are not limited to those formed by dividing the rod packings 45 and 46 by a plurality of ring segments. In addition, various deformations are conceivable.

1 Piston pump 2 Cylinder 3 Cylinder liner 4 Cylinder head chamber 5 Piston 6 Valve head 7 Cylinder head 8 Supply port 9 Discharge port 10 Discharge path 11 Discharge valve 12 Piston rod 13 Valve accommodating chamber 16 Protrusion 17 Suction path 18 Piston ring groove 19 Piston Ring 21 Outlet opening 28, 29 Outlet 30 Seal 31 Retainer 32 Coil spring 33 Nitrogen gas supply path 35-40 Packing section 41, 42 Spacer 41a, 42a Circular passage 41b, 42b Pressurized passage 45, 46 Rod packing 47, 48 Ring segments 47a, 48a Inner circumference 47b, 48b Outer circumference 48c Spring groove 49, 50 Slit 49a, 50a Opening 51 Tension spring 52 Packing holder 53 Packing 101 Piston pump 102 Cylinder 103 Cylinder liner 104 Cylinder head chamber 105 Piston 106 Valve Head 107 Cylinder head 108 Supply port 109 Discharge port 110 Discharge path 112 Piston rod 113 Valve accommodating chamber 118 Piston ring groove 119 Piston ring 121 Sealing part 122, 123 Rod packing 124, 125 Ring segment 128, 129 Discharge port L0, L1 Length

Claims (5)

A cylinder (2) having a cylinder liner (3) inside, a piston (5) reciprocally inserted into the cylinder liner, and a piston connected to the piston and inserted into the cylinder to insert the piston. A piston rod (12) that reciprocates in the cylinder liner, and a seal portion (30) that is arranged between the piston rod and the cylinder to make the space between the piston rod and the cylinder liquid-tight or airtight. An annular rod packing (45, 46) disposed on the seal portion and having an inner peripheral portion formed along the outer peripheral portion of the piston rod, and the rod packing are urged toward the piston rod side. The rod packing of the piston pump is provided with an urging means (51) for pressing the rod packing against the piston rod, and the rod packing is a plurality of ring segments (47) which are continuously provided in the circumferential direction. , 48), and the individual ring segment has an opening (49a, 50a) in the inner peripheral portion (47a, 48a) and has a slit (49, 50) extending toward the outer peripheral portion (47b, 48b). A rod packing of a piston pump, wherein the slit penetrates the ring segment in the axial direction and does not penetrate in the radial direction. The ring segment (47, 48) is characterized by having the opening (49a, 50a) of the slit (49, 50) at the central portion of the inner peripheral portion (47a, 48a) in the circumferential direction. The rod packing of the piston pump according to claim 1. The rod packing of a piston pump according to claim 1 or 2, wherein the rod packing (45, 46) can be used at an extremely low temperature . A plurality of the rod packings (45, 46) are arranged so as to be coaxially stacked in a layer in the axial direction, and the slits (49, 46) of the rod packing adjacent to the plurality of the stacked rod packings. 50) The rod packing of the piston pump according to any one of claims 1 to 3, wherein the rod packings of the piston pump are arranged so as to be displaced from each other in the circumferential direction. Said slit (49, 50), said characterized in that it extends linearly the inner peripheral portion of the ring segments (47, 48) from (47a, 48a) radially outwardly, of claims 1 to 4 The rod packing of the piston pump described in either.

Images