JP2018051691A - Ring Case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ring case that facilitates fitting of piston rings into ring grooves provided in a piston and can determine states of the piston rings fitted into the ring grooves before the piston is inserted into a cylinder bore.SOLUTION: A ring case 1 comprises an annular main body part 11 which has an inner peripheral surface 11a and an outer peripheral surface 11b and a plurality of pins 21 to be attached to the inner peripheral surface 11a of the main body part 11. Each of the plurality of pins 21 has a taper part 23 and a columnar holding part 22. A diameter S2 of an inscribed circle 32 by the taper part 23 varies so as to be closer to a nominal diameter Rp of a piston ring 4 as approaching the holding part 22, and a dimeter S1 of an inscribed circle 31 by the holding part 22 is substantially identical to the nominal diameter Rp. The main body part 11 has a visual recognition area at which a space surrounded by the inner peripheral surface 11a is allowed to be visually recognized from the outer peripheral surface 11b side.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a ring case, and more particularly to a ring case that assists the fitting of a piston ring into a ring groove of a piston and maintains the fitting state of the piston ring in the ring groove.

  The assembly process of the engine includes a process of inserting a piston with a piston ring attached into a cylinder bore of a cylinder block. In this step, it is necessary to prevent the piston ring from being caught and damaged by the cylinder block. For this reason, in the above process, for example, using a dedicated jig (taper cone) having a tapered inner surface, the piston is inserted into the cylinder bore while fitting the piston ring into the ring groove of the piston (see Patent Document 1 below) reference).

JP 2009-107036 A

  In the conventional method, it is difficult to confirm from the outside whether or not the piston ring is properly fitted in the ring groove after the piston is inserted into the cylinder bore using the dedicated jig. For this reason, for example, after assembling the engine, it is determined whether or not the piston ring is normally fitted in the ring groove by measuring the cranking torque or compression pressure of the piston.

  If it is determined that the piston ring is not properly fitted in the ring groove, a complicated operation such as removing the piston from the cylinder bore after the measurement is required to correct this. Therefore, from the viewpoint of improving the efficiency of the engine assembly process, it is easy to fit the piston ring into the ring groove provided in the piston, and before the piston is inserted into the cylinder bore, the piston ring is fitted into the ring groove. There is a demand for a technique that can determine the loading state.

  The present invention provides a ring case that facilitates fitting of a piston ring into a ring groove provided in the piston and that can determine the fitting state of the piston ring into the ring groove before the piston is inserted into the cylinder bore. With the goal.

  A ring case according to an aspect of the present invention is a ring case that assists in fitting a piston ring into a ring groove of a piston and maintains a fitting state of the piston ring in the ring groove, and includes an inner peripheral surface and an outer peripheral surface. And a plurality of pins attached to the inner peripheral surface of the main body portion and extending along the width direction of the main body portion, and each of the plurality of pins includes a tapered portion and a tapered portion. A diameter of the first inscribed circle due to the tapered portion changes so as to approach the nominal diameter of the piston ring as it approaches the holding portion, The diameter of the tangent circle substantially coincides with the nominal diameter, and the main body has a visual recognition area for visually recognizing the space surrounded by the inner peripheral surface from the outer peripheral surface side.

  In this ring case, a plurality of pins are attached to the inner peripheral surface of the main body portion, and the diameter of the first inscribed circle due to the tapered portion of the pins approaches the nominal diameter of the piston ring as it approaches the holding portion. Has changed. In such a ring case, a piston in which a piston ring is mounted in a ring groove is inserted from the tip end side of the tapered portion. As a result, the diameter of the piston ring can be reduced by contacting the taper portion, and the piston ring can be easily fitted into the ring groove. In addition, each pin has a columnar holding portion that is provided continuously to the tapered portion, and the diameter of the second inscribed circle by the holding portion of each pin substantially matches the nominal diameter. . In addition, since the piston diameter is almost the same as the nominal diameter of the piston ring, the piston ring can be inserted into the ring case and the piston ring fitted into the ring groove can be maintained. It can be held well by the part. Here, the main body has a visual recognition area for visually recognizing the space surrounded by the inner peripheral surface from the outer peripheral surface side. Thereby, in the piston with the ring case attached, it can be easily determined by visual observation or the like whether or not the piston ring is properly fitted into the ring groove. Therefore, by using the ring case, it is possible to determine the fitting state of the piston ring in the ring groove before the piston is inserted into the cylinder bore, and to reduce the defect rate due to the piston ring in the engine assembly process.

  The inner peripheral surface may be provided with a plurality of grooves into which a plurality of pins are fitted, and a shaft support portion that pivotally supports a plurality of pins fitted into the plurality of grooves around an axis. In this case, it is possible to prevent the pin fitted in the groove from dropping from the main body portion by the shaft support portion. In addition, since the pin is rotatably supported around the axis, the piston with the ring case attached can be smoothly rotated with respect to the main body while being held by the holding portion. For this reason, by rotating the piston while fixing the ring case, it is possible to change the position of the piston ring visible from the outside of the ring case through the visual recognition region. Therefore, it is possible to easily determine the fitted state of the entire piston ring through the visual recognition area.

  The visual recognition area may be configured by forming at least a part of the main body portion from a transparent material. In this case, the fitting state of the piston ring with respect to the ring groove can be easily determined from the transparent portion of the main body.

  According to the ring case according to the present invention, it is possible to determine the fitting state of the piston ring into the ring groove before the piston is inserted into the cylinder bore.

It is a perspective view which shows the ring case which concerns on 1 aspect of this invention. 2A is a schematic side view showing a state in which the ring case is mounted on the piston, FIG. 2B is a schematic cross-sectional view of FIG. 2A, and FIG. FIG. 3 is a schematic enlarged view of a region surrounded by an alternate long and short dash line in FIG. FIG. 3A is a schematic plan view of the piston ring in a free state, and FIG. 3B is a schematic plan view of the piston ring in a state where the joint portion is closed. . 4A is a plan view of the ring case, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG. 4A. FIG. 5A is an exploded perspective view of the ring case. It is a figure for demonstrating the insertion method to the cylinder bore of the piston using the ring case which concerns on this embodiment. It is a figure for demonstrating the insertion method to the cylinder bore of the piston using the ring case which concerns on this embodiment.

  Hereinafter, preferred embodiments of a ring case according to an aspect of the present invention will be described in detail with reference to the drawings. First, an outline of a ring case according to the present embodiment and a usage example of the ring case will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a ring case according to the present embodiment. 2A is a schematic side view showing a state in which the ring case is mounted on the piston, FIG. 2B is a schematic cross-sectional view of FIG. 2A, and FIG. FIG. 3 is a schematic enlarged view of a region surrounded by an alternate long and short dash line in FIG.

  The ring case 1 shown in FIGS. 1 and 2A and 2B assists the fitting of the piston rings 4 to 6 into the ring grooves 3a to 3c of the piston 3 with a plurality of pins 21 (details will be described later). At the same time, it is a ring case that holds the piston rings 4 to 6 fitted in the ring grooves 3 a to 3 c with a plurality of pins 21. The ring case 1 is a cover that covers at least a part of the side surface of the piston 3 so that the piston rings 4 to 6 fitted in the ring grooves 3 a to 3 c are fitted (fitted state). Further, the ring case 1 serves as an insertion assisting member for inserting the piston 3 in which the piston rings 4 to 6 are fitted into the ring grooves 3a to 3c, respectively, into the cylinder bore 7 (FIGS. 7A and 7B). Is also used. For this reason, ring case 1 can also be called a ring case for piston incorporation. When the ring case 1 is attached to the piston 3, the ring case 1 is installed so as not to cover the pin hole 3d into which the piston pin is inserted in the piston 3. Thereby, the insertion of the piston pin into the pin hole 3d is not hindered by the ring case 1.

  In addition, since at least a part of the ring case 1 is formed of a transparent material as will be described later, the piston 3 and the piston rings 4 to 6 covered by the ring case 1 are visible. For example, as shown in FIG. 2 (c), even when the ring case 1 is attached to the piston 3, the state of the piston ring 6 that is an oil ring fitted into the ring groove 3 c is changed to the ring case 1. Can be seen through. Similarly, the state of the piston ring 4 which is a top ring fitted into the ring groove 3a and the state of the piston ring 5 which is a second ring fitted into the ring groove 3b can also be visually recognized through the ring case 1.

  FIG. 3A is a schematic plan view of the piston ring 4 in a free state, and FIG. 3B is a schematic plan view of the piston ring 4 in a state where the joint portion is closed. As shown in FIG. 3 (a), the piston ring 4 has a split ring shape provided with a joint portion 4a. Hereinafter, as illustrated in FIG. 3B, the outer diameter of the piston ring 4 in a state where the joint portion 4 a is closed is referred to as a nominal diameter Rp of the piston ring 4. The state in which the joint portion 4a is closed is a state in which the piston ring 4 has a predetermined joint gap s1. The nominal diameter Rp of the piston ring 4 is the same as the nominal diameter of the piston rings 5 and 6. The nominal diameter Rp is substantially the same for both the diameter R11 of the piston 3 (see FIG. 2B) and the inner diameter R21 of the cylinder bore 7 (see FIG. 7A). The “substantially” in the present embodiment is a concept including an error of a maximum of several percent unless otherwise specified below. From the viewpoint of easily inserting the piston 3 having the piston rings 4 to 6 attached to the cylinder bore 7, the diameter R11 of the piston 3 is preferably slightly smaller than the nominal diameter Rp, and the inner diameter R21 of the cylinder bore 7 is the nominal diameter. A slightly larger value than Rp is preferable.

  Next, the shape of the ring case 1 will be described with reference to FIGS. 4 and 5 in addition to FIG. 4A is a plan view of the ring case, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG. 4A. FIG. 5 is an exploded perspective view of the ring case.

  The ring case 1 shown in FIGS. 1, 4A, 4B, and 5 includes an annular main body 11 having an inner peripheral surface 11a, an outer peripheral surface 11b, and side surfaces 11c and 11d, and a main body 11. And a plurality of pins 21 attached to the inner peripheral surface 11a.

  The main body 11 is a member that supports the pin 21 that is in contact with the piston 3 and the piston rings 4 to 6 when mounted on the piston 3. Therefore, when the piston 3 is inserted into the ring case 1, the main body 11 supports the pin 21 that contacts the piston 3 or the like without contacting the piston 3 or the like. The whole main body 11 is made of a transparent material. The transparent material is, for example, a resin having transparency such as an acrylic resin, or glass. For this reason, the main-body part 11 is comprised so that it may have the visual recognition area | region which makes the space enclosed by the internal peripheral surface 11a visible from the outer peripheral surface 11b side. The inner peripheral surface 11 a of the main body 11 has an annular flat surface 12 and an annular tapered surface 13.

  The flat surface 12 is a surface extending from the side surface 11d of the main body 11 toward the side surface 11c. The flat surface 12 extends substantially parallel to the outer peripheral surface 11b and is substantially perpendicular to the side surface 11d. The inner diameter R1 of the portion of the main body 11 where the flat surface 12 is provided is larger than the nominal diameter Rp of the piston ring 4. In the present embodiment, the inner diameter R1 is larger than the nominal diameter Rp by about several millimeters at the maximum.

  The tapered surface 13 is an inclined surface extending from the end of the flat surface 12 on the side surface 11c side toward the side surface 11c side. The taper surface 13 is inclined toward the outer peripheral surface 11b side toward the side surface 11c side. For this reason, the internal diameter of the part in which the taper surface 13 is provided in the main-body part 11 becomes narrow as it goes to the flat surface 12, and is more than the internal diameter R1.

  A plurality of grooves 14 extending along the width direction of the main body 11 are provided in the flat surface 12 and the tapered surface 13 of the inner peripheral surface 11a. A pin 21 is fitted in each of the grooves 14. The grooves 14 are separated from each other along the circumferential direction of the main body 11. From the viewpoint of stably holding the piston 3 and the piston rings 4 to 6, it is preferable that the distances between the adjacent grooves 14 in the circumferential direction are substantially the same. Each of the plurality of grooves 14 is provided by, for example, end milling. In the present embodiment, a total of eight grooves 14 are provided in the main body portion 11, but at least a plurality of the grooves 14 may be provided.

  On the inner peripheral surface 11a, on the side of the side surface 11c from the tapered surface 13, an annular shaft support portion 15 that supports each pin 21 fitted in the corresponding groove 14 is provided. For example, each pin 21 is pivotally supported around the shaft by being hooked to the shaft support portion 15 (details will be described later). The shaft support portion 15 is a step that protrudes from the side surface 11c side of the tapered surface 13 on the inner peripheral surface 11a. The protrusion amount of the shaft support portion 15 is not particularly limited as long as each pin 21 can be supported and insertion of the piston 3 and the piston rings 4 to 6 into the main body portion 11 is not hindered.

  The outer diameter R2 of the main body 11 is larger than the inner diameter R21 (see FIG. 7A) of the cylinder bore 7 into which the piston 3 is inserted. The outer diameter R2 is preferably a size that allows the main body 11 to be stably placed on the cylinder block 8 (see FIG. 7A). That is, it is preferable that the thickness of the main body 11 corresponding to “outer diameter R2−inner diameter R1” is a size that can be stably placed on the cylinder block 8. The outer diameter R2 is preferably about 1.2 to 1.5 times the inner diameter R1, for example.

  The plurality of pins 21 are attached to the main body portion 11 to assist the fitting of the piston rings 4 to 6 into the ring grooves 3a to 3c, and the fitting state of the piston rings 4 to 6 with respect to the ring grooves 3a to 3c. It is a member to hold. Each pin 21 is a member made of, for example, a metal or an alloy such as SUS and having a tapered tip. Each pin 21 extends along the width direction of the main body 11 when fitted into the corresponding groove 14. Each of the plurality of pins 21 has a columnar holding portion 22, a tapered portion 23 provided continuously to the holding portion 22, and a locking portion 24 locked to the main body portion 11. Note that the length of each pin 21 is substantially the same as the width W1 of the main body 11. Note that the tip surface 21 a opposite to the tapered tip of the pin 21 is a flat surface and is substantially flush with the side surface 11 d of the ring case 1.

  The holding part 22 is a columnar part that holds the piston 3 and the piston rings 4 to 6 inserted into the ring case 1. The holding portion 22 is fitted into a region provided on the flat surface 12 in the groove 14. A region 22 a exposed from the groove 14 in the holding portion 22 protrudes inward of the main body portion 11 from the flat surface 12. Here, the diameter S1 of the inscribed circle 31 (second inscribed circle) by the holding portion 22 is smaller than the inner diameter R1 and substantially coincides with the nominal diameter Rp of the piston ring 4. The inscribed circle 31 is a virtual circle that touches a point that protrudes inwardly of the main body 11 in the region 22 a of each holding portion 22 when viewed along the width direction of the main body 11. For this reason, the distance from the center of the inscribed circle 31 to each pin 21 corresponds to the radius of the inscribed circle 31.

  In the present embodiment, that the diameter S1 substantially matches the nominal diameter Rp is that the diameter S1 is completely the same as the nominal diameter Rp or slightly different from the nominal diameter Rp. For example, when the nominal diameter Rp of the piston ring 4 is 78 mm, the diameter S1 is 77.9 mm to 78.1 mm (preferably 77.95 mm to 78.05 mm, more preferably 77.98 mm to 78.02 mm). is there. Since the diameter S1 is slightly larger than the nominal diameter Rp, the main body 11 is preferably attached to the piston 3 so as to be rotatable in the circumferential direction.

  The tapered portion 23 is a portion that assists in fitting the piston rings 4 to 6 into the ring grooves 3 a to 3 c when the piston 3 is inserted into the ring case 1. The tapered portion 23 extends from the end on the side surface 11c side of the holding portion 22 while reducing the diameter so that the tip thereof is tapered. The tapered portion 23 is fitted in a region provided on the tapered surface 13 in the groove 14. A region 23 a exposed from the groove 14 in the tapered portion 23 protrudes inward of the main body portion from the tapered surface 13. Here, the diameter S2 of the inscribed circle 32 (first inscribed circle) by the tapered portion 23 changes so as to approach the nominal diameter Rp of the piston ring 4 as it approaches the holding portion 22. In other words, the diameter S2 of the inscribed circle 32 changes according to the protruding amount of the region 23a of the tapered portion 23. For this reason, the diameter S2 is sufficiently larger than the nominal diameter Rp at the tip portion of the tapered portion 23, and gradually decreases toward the holding portion 22 side in the width direction. And the diameter S2 of the part which follows the holding | maintenance part 22 in the taper part 23 is substantially corresponded with the nominal diameter Rp. Note that the diameter S2 is sufficiently larger than the nominal diameter Rp, for example, the diameter S2 is larger than the maximum outer diameter of the piston ring 4 in a free state. From the viewpoint of easily inserting the piston 3 to which the piston rings 4 to 6 are attached, the diameter S2 is more preferably about several mm larger than the maximum outer diameter. Alternatively, the diameter S2 is preferably about 10% larger than the diameter S1.

  The locking portion 24 is a portion that prevents the pin 21 from dropping from the main body portion 11 by being locked to the main body portion 11, and is provided at the tip of the tapered portion 23. The locking portion 24 has a drawn portion 24a that has been drawn and a tip portion 24b that is located on the opposite side of the tapered portion 23 with the drawn portion 24a interposed therebetween. The diameter of the throttle portion 24a is smaller than the diameter of the tip portion 24b. For example, the diameter of the narrowed portion 24a is about 1/2 to 3/4 of the diameter of the distal end portion 24b. The shaft support portion 15 of the main body 11 enters the throttle portion 24 a and the tip portion 24 b is locked to the shaft support portion 15, whereby the pin 21 is pivotally supported by the shaft support portion 15.

  Next, a method for inserting the piston 3 into the cylinder bore 7 using the ring case 1 according to the present embodiment will be described with reference to FIGS. 6 and 7.

  First, as shown in FIG. 6A, a piston 3 is prepared in which piston rings 4 to 6 are mounted in ring grooves 3a to 3c, respectively. Next, as shown in FIG. 6B, the piston 3 to which the piston rings 4 to 6 are attached is inserted into the ring case 1 in which the pins 21 are fitted in the respective grooves 14. At this time, the piston 3 is inserted into the ring case 1 from the side surface 11 c side of the main body 11 with the top land 3 e of the piston 3 facing the opposite side of the ring case 1. As the piston 3 moves toward the side surface 11 d of the ring case 1, each of the piston rings 4 to 6 comes into contact with the exposed region 23 a of the tapered portion 23 of each pin 21. Each of the piston rings 4 to 6 is reduced in diameter to the nominal diameter Rp as the piston 3 moves. Thereby, each of the piston rings 4-6 will be in a fitting state with respect to the corresponding ring grooves 3a-3c.

  Next, the piston 3 and the piston rings 4 to 6 are held by the holding portion 22 by further inserting the piston 3 into the ring case 1. At this time, the region 22a of each holding portion 22 in the ring case 1 contacts the piston 3 and the piston rings 4 to 6 to hold the piston 3 and the piston rings 4 to 6. As a result, as shown in FIGS. 2A and 2B, the ring case 1 is mounted on the piston 3 so as to maintain the fitted state of the piston rings 4 to 6. In addition, the flat surface 12 of the inner peripheral surface 11a does not contact the piston 3 and the piston rings 4-6. Thereafter, the piston pin and the connecting rod (connecting rod) are attached to the piston 3 with the ring case 1 attached to the piston 3. However, the mounting of the piston pin and the connecting rod to the piston 3 may be performed before the ring case 1 is mounted, or may be performed before the piston rings 4 to 6 are mounted.

  Here, the fitting state of the piston rings 4 to 6 in the piston 3 to which the ring case 1 is attached is confirmed. Specifically, the main body 11 is fixed and the piston 3 is rotated to check whether the piston rings 4 to 6 are normally accommodated in the corresponding ring grooves 3a to 3c. This confirmation is performed using, for example, visual observation or an image analysis camera. Further, by measuring the torque at the time of rotation of the piston 3, it is determined whether or not the fitted state of the piston rings 4 to 6 is normal. When it is determined that the piston rings 4 to 6 are not properly fitted, the piston 3 is removed from the ring case 1 and the piston rings 4 to 6 are adjusted or replaced.

  Next, as shown in FIG. 7A, when it is determined that the piston rings 4 to 6 are fitted normally, a portion (piston skirt) opposite to the top land 3e in the piston 3 is placed in the cylinder bore 7. And the ring case 1 is placed on the cylinder block 8. A side surface 11 d of the ring case 1 and a tip end surface 21 a of the pin 21 are in contact with the upper end surface of the cylinder block 8 (the surface on which the ring case 1 is placed in the cylinder block 8). At this time, the tip surface 21a of the pin 21 only needs to be in contact with at least the upper end surface of the cylinder block 8, and the side surface 11d of the ring case 1 may not be in contact. In this case, there is a slight gap (gap) between the side surface 11d and the tip surface 21d, and the pin 21 is attached to the ring case 1 so that the tip surface 21d protrudes from the side surface 11d.

  Then, by pressing the top land 3e of the piston 3, as shown in FIG. 7B, the piston rings 4 to 6 are held in the corresponding ring grooves 3a to 3c while maintaining the piston 3 Is inserted into the cylinder bore 7.

  In the ring case 1 according to the present embodiment described above, a plurality of pins 21 are attached to the inner peripheral surface 11a of the main body 11, and the diameter S2 of the inscribed circle 32 by the tapered portion 23 of each pin 21 is: It changes so that it may approach the nominal diameter Rp of the piston ring 4 as the holding | maintenance part 22 is approached. The piston 3 in which the piston rings 4 to 6 are respectively mounted in the ring grooves 3 a to 3 c is inserted into the ring case 1 from the front end side of the tapered portion 23. Thereby, the piston rings 4 to 6 are brought into contact with the taper portion 23 to be reduced in diameter, and the piston rings 4 to 6 can be easily fitted into the ring grooves 3a to 3c. That is, the fitting of the piston rings 4 to 6 into the ring grooves 3 a to 3 c can be assisted by the tapered portions 23 of the pins 21. In addition, each pin 21 has a holding portion 22 provided continuously to the tapered portion 23, and the diameter S1 of the inscribed circle 31 by the holding portion 22 of each pin 21 is substantially the same as the nominal diameter Rp. Match. Further, since the diameter R11 of the piston 3 is substantially the same as the nominal diameter Rp of the piston ring 4, when the piston 3 is further inserted and attached to the ring case 1, not only the piston 3 but also the ring grooves 3a to 3c. The holding state of the piston rings 4 to 6 can be favorably held by the holding portion 22. Here, the main-body part 11 has the visual recognition area | region which makes the space enclosed by the internal peripheral surface 11a visible from the outer peripheral surface 11b side by being formed with the transparent material. Thereby, in the piston 3 to which the ring case 1 is attached, whether or not the piston rings 4 to 6 are normally fitted can be easily determined visually. Therefore, by using the ring case 1, it is possible to determine whether the piston rings 4 to 6 are fitted into the ring grooves 3a to 3c before the piston 3 is inserted into the cylinder bore 7.

  Moreover, even if it is a case where the piston 3 with which the ring case 1 was mounted | worn is conveyed or conveyed, the fitting state of piston rings 4-6 is maintained. For this reason, it is possible to prevent the piston rings 4 to 6 from jumping out of the ring grooves 3a to 3c. Thereby, it can prevent suitably that piston rings 4-6 collide with a certain object, and piston rings 4-6 are damaged. Moreover, since the main-body part 11 has covered the ring grooves 3a-3c, it can also suppress that a foreign material mixes in the ring grooves 3a-3c during the transportation of the piston 3, etc.

  In addition, the ring case 1 may be used as an insertion assisting member for the piston 3 and the piston 3 may be inserted into the cylinder bore 7. In this case, the piston 3 whose piston rings 4 to 6 are held in the ring case 1 can be inserted into the cylinder bore 7 as it is. As a result, the defect rate due to the piston rings 4 to 6 in the assembly process of the engine can be reduced, and the measurement process of the cranking torque or the compression pressure of the piston 3 can be omitted, and the assembly process can be made efficient.

  Furthermore, the chamfering amount at the upper end 7a of the cylinder bore 7 can be reduced by using the ring case 1 as the insertion assisting member. By reducing the chamfering amount at the upper end 7a, the ring groove 3a can be provided on the top land 3e side. Thereby, the piston ring 4 can be brought closer to the top land 3e side, and the heat dissipation of the piston 3 by the piston ring 4 can be improved.

  The inner peripheral surface 11a is provided with a plurality of grooves 14 into which the plurality of pins 21 are fitted, and a shaft support portion 15 that pivotally supports the plurality of pins 21 fitted into the plurality of grooves 14 around the axis. It has been. For this reason, the pin 21 fitted in the groove 14 can be prevented from dropping from the main body 11 by the shaft support 15. In addition, since the pin 21 is rotatably supported around the axis, the piston 3 to which the ring case 1 is mounted can be smoothly rotated with respect to the main body 11 while being held by the holding portion 22. It becomes. For this reason, by rotating the piston 3 while fixing the ring case 1, the positions of the piston rings 4 to 6 that can be visually recognized from outside the ring case 1 can be changed via the visual recognition region. For example, in the piston rings 4 to 6, the fitted state of the portion that could not be visually recognized by the pin 21 can be determined by rotating the piston 3. Therefore, it is possible to easily determine the fitted state of the entire piston rings 4 to 6 through the visual recognition area.

  The present invention is not limited to the above embodiment, and various other modifications are possible. For example, in the said embodiment, although the whole main-body part 11 is formed with the transparent material, it is not restricted to this. For example, the visual recognition area may be configured by forming at least a part of the main body 11 from a transparent material. Even in this case, it is possible to easily determine whether the piston rings 4 to 6 are fitted into the ring grooves 3 a to 3 c from the transparent portion of the main body 11.

  In the above embodiment, each pin 21 is simply fitted in the groove 14, but each pin 21 may be fixed by, for example, an adhesive. That is, each pin 21 does not need to be rotatably fitted in the corresponding groove 14. In this case, the shaft support portion 15 may not be provided in the main body portion 11, and the locking portion 24 may not be provided in each pin 21. Moreover, although the holding | maintenance part 22 is a cylindrical member, a prismatic member may be sufficient. In this case, the holding portion 22 is fixed by an adhesive or the like, and the shaft support portion 15 and the locking portion 24 may not be provided.

  In the above embodiment, the timing for attaching the ring case 1 to the piston 3 is not particularly limited as long as it is before the piston 3 is inserted into the cylinder bore 7. For example, the timing at which the ring case 1 is attached to the piston 3 may be before the piston 3 is delivered to the engine manufacturer. In this case, in the assembly process of the engine, the piston 3 held in a state where the piston rings 4 to 6 are fitted in the ring grooves 3 a to 3 c in advance can be inserted into the cylinder bore 7 as it is. Thereby, the assembly process of the engine can be further improved. Further, in the transportation when the piston 3 is delivered to the engine manufacturer, the ring case 1 can suitably prevent the piston rings 4 to 6 from being damaged.

  DESCRIPTION OF SYMBOLS 1 ... Ring case, 3 ... Piston, 3a-3c ... Ring groove, 3e ... Top land, 4-6 ... Piston ring, 7 ... Cylinder bore, 8 ... Cylinder block, 11 ... Main-body part, 11a ... Inner peripheral surface, 11b ... Peripheral surface, 12 ... flat surface, 13 ... tapered surface, 14 ... groove, 15 ... shaft support, 21 ... pin, 22 ... holding part, 23 ... taper part, 24 ... locking part, 31 ... inscribed circle (second) Inscribed circle), 32 ... inscribed circle (first inscribed circle), R1 ... inner diameter, Rp ... nominal diameter, S1, S2 ... diameter.

Claims (3)

A ring case for assisting the fitting of the piston ring into the ring groove of the piston and holding the fitting state of the piston ring in the ring groove;
An annular main body having an inner peripheral surface and an outer peripheral surface;
A plurality of pins attached to the inner peripheral surface of the main body portion and extending along the width direction of the main body portion,
Each of the plurality of pins has a tapered portion and a columnar holding portion provided continuously to the tapered portion,
The diameter of the first inscribed circle by the tapered portion changes so as to approach the nominal diameter of the piston ring as it approaches the holding portion,
The diameter of the second inscribed circle by the holding portion is substantially the same as the nominal diameter,
The main body has a visual recognition area for visually recognizing a space surrounded by the inner peripheral surface from the outer peripheral surface side.
Ring case.   The inner peripheral surface is provided with a plurality of grooves into which the plurality of pins are fitted, and a shaft support portion that rotatably supports the plurality of pins fitted into the plurality of grooves around an axis. The ring case according to claim 1.   The ring case according to claim 1 or 2, wherein the visual recognition area is configured by forming at least a part of the main body portion from a transparent material.

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