JP6012096B2 - Piston ring assembly device - Google Patents

Description

  The present invention relates to a piston ring assembling apparatus for assembling a piston ring to an engine piston.

  Piston rings are fitted into pistons used in automobile engines and the like in order to prevent leakage of combustion gas from the combustion chamber and to adjust the oil film thickness with the cylinder. For example, the following Patent Document 1 discloses a piston ring assembling device that automatically assembles a piston ring to a piston. Specifically, a piston ring held in an expanded state is arranged on the outer periphery of the piston placed with the top surface facing downward, and the height of the piston ring groove and the piston ring is matched. By releasing the expanded diameter holding of the piston ring, the diameter of the piston ring is reduced and mounted in the ring groove of the piston.

JP 2011-255427 A

  Normally, the clearance between the piston ring thickness and the groove width of the piston ring groove is very small. Therefore, when assembling the piston ring in the ring groove, it is necessary to match the height of the ring groove with the height of the piston ring with high accuracy. There is. In the above-mentioned Patent Document 1, the height of the ring groove and the piston ring are made to coincide by bringing the top surface of the piston into contact with the receiving surface (piston mounting portion) and positioning the piston.

  However, since the top surface of the piston is usually a surface that has not been finished, the surface accuracy is not so high. For this reason, if the piston is positioned with reference to the top surface as described above, the position of the piston, and hence the height of the ring groove, becomes unstable, and the height of the ring groove may not match the height of the piston ring. In this case, there is a possibility that the piston ring does not fit into the ring groove, or the piston ring fits into the ring groove while interfering with the periphery of the ring groove, thereby damaging the outer peripheral surface of the piston.

  At present, the shape of the receiving surface is designed by trial and error. However, it is very difficult to design the receiving surface to surely prevent the above-described problems. Also, in recent years, the shape of the top surface of the piston has become complicated in order to further improve the fuel efficiency, so that it is increasingly difficult to design the shape of the receiving surface by trial and error as described above. Furthermore, after the receiving surface shape is determined and production is started, the piston top surface shape may be redesigned. In such a case, the receiving surface shape needs to be redesigned. It becomes a problem that it becomes bulky.

  In view of the circumstances as described above, the present invention accurately matches the positions of the piston ring and the ring groove of the piston, reliably prevents poor piston ring assembly and damage to the piston, and reduces production costs. With the goal.

  The present invention made to achieve the above object includes a piston holding portion that holds a piston by inserting a holding pin into a pair of pin holes provided in the piston, and a ring that holds the piston ring in an expanded state. A holding unit and a driving unit that moves the piston holding unit in the axial direction with respect to the ring holding unit in a state where the piston and the piston ring are coaxially arranged, and the piston holding unit is relatively moved in the axial direction by the driving unit. By inserting the piston into the inner periphery of the piston ring, the piston ring groove is positioned with respect to the piston ring, and the piston ring is released from the expanded diameter by the ring holding portion, thereby reducing the diameter of the piston ring. , A piston ring assembly device for assembling a piston ring in a ring groove. It is characterized in that for positioning of the ring groove.

  Thus, in the piston ring assembling apparatus of the present invention, when positioning the piston ring groove with respect to the piston ring, it is not based on the top surface of the piston, but for connecting rods provided on the piston. Based on pin hole. Normally, the pin hole is a high-precision surface that has been finished, so by using the pin hole as a reference, the piston's ring groove is located on the piston ring regardless of the surface accuracy and shape of the piston's top surface. Can be positioned accurately. In addition, by using the pin hole as a reference, it is not necessary to change the design of the piston ring assembly device even when the design of the top surface shape of the piston is changed, so that the production cost can be reduced. .

  Since the piston is held by the holding pins inserted into the pair of pin holes, when the piston is transported, the piston may rotate around the pin holes and the ring groove may be inclined with respect to the piston ring. There is. Therefore, if the piston holding portion is provided with a rotation restricting portion that restricts rotation around the pin hole of the piston by contacting the end face of the piston skirt portion, the piston can be held in an accurate posture. The positioning accuracy of the ring groove with respect to the piston ring can be improved.

  The holding pin is preferably provided with a centering mechanism for centering with the pin hole. As described above, since the piston can be held at an accurate position through the pin hole by centering the holding pin and the pin hole, the positioning accuracy of the piston ring groove with respect to the piston ring can be further increased. .

  Positioning of the piston ring groove with respect to the piston ring is performed by, for example, providing a stopper in the piston holding part and a stopper receiver in the ring holding part, and moving the stopper and the stopper receiver in the axial direction (relative movement of the piston holding part with respect to the ring holding part). Direction).

  As described above, according to the present invention, by positioning the piston with reference to the pin hole, the piston ring groove can be accurately positioned at the same axial position as the piston ring regardless of the surface accuracy and shape of the top surface of the piston. Therefore, it is possible to reliably prevent poor piston ring assembly and damage to the piston, and reduce production costs.

It is a partial cross section front view of the piston ring assembly | attachment apparatus which concerns on one Embodiment of this invention. It is a partial cross section side view of the said piston ring assembly apparatus. (A)-(c) is a front view for demonstrating the procedure which hold | maintains a piston by a piston holding | maintenance part. It is a partial cross section front view of the said piston ring assembly apparatus, and shows the state which has arrange | positioned the ring groove | channel of a piston to the same height as a piston ring. It is a partial cross section front view of the said piston ring assembly apparatus, and shows the state which assembled | attached the piston ring to the piston.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, a piston ring assembling apparatus 1 according to an embodiment of the present invention includes a piston holding part 10 that holds a piston P and a ring holding part that holds a piston ring R in an expanded state. 20 and a drive unit (not shown) that moves the piston holding unit 10 with respect to the ring holding unit 20. In this embodiment, the ring holding part 20 is a fixed side, the piston holding part 10 is a movable side, and the central axis direction of the piston P and the piston ring R is the vertical direction.

  The piston holding part 10 is movable in the vertical direction and the horizontal direction by the drive part, and has a pair of holding pins 11, a rotation restricting part 12, and a stopper 13. The pair of holding pins 11 are provided so as to be close to and away from each other in the diameter direction of the piston P, and can be inserted into a pair of pin holes P1 provided in the piston P (see FIG. 1). In the illustrated example, a pair of holding pins 11 are provided at the lower ends of the pair of arms 14 that can approach and separate from each other in the diameter direction of the piston P. The holding pin 11 has a centering mechanism for centering with the pin hole P1. In the illustrated example, the holding pin 11 is tapered toward the tip side (the central axis side of the piston P), its large diameter portion is larger than the inner diameter of the pin hole P1, and its small diameter portion is the pin hole. By setting the diameter smaller than the inner diameter of P1, a centering mechanism is configured.

  The rotation restricting portion 12 is provided at a position where it can come into contact with the end face (upper end face in FIGS. 1 and 2) of the skirt portion P2 of the piston P held by the holding pin 11. In the present embodiment, as shown in FIG. 2, a pair of rotation restricting portions 12 are provided on both sides of the holding pin 11 in the horizontal direction. The pair of rotation restricting portions 12 abuts at two locations on both sides in the horizontal direction of the pair of pin holes P1 among the end surfaces of the skirt portion P2 of the piston P held by the holding pins 11. Accordingly, the piston P cannot rotate in any direction around the pin hole P1, and the posture is fixed.

  The stopper 13 is provided at a position where it comes into contact with a stopper receiver 23 provided on the fixed member. In the illustrated example, a pair of stoppers 13 are provided so as to protrude outward from the pair of arms 14, respectively, and are disposed directly above the stopper receiver 23.

  The ring holding part 20 holds the piston ring R cut out from a cutting device (not shown) in an expanded state. The ring holding part 20 includes a main body part 21 having a hole 21 a into which the piston P is inserted, a shutter 22 provided on the inner periphery of the main body part 21, a stopper receiver 23, and a diameter expansion mechanism that expands the diameter of the piston ring R. (Not shown). The main body portion 21 is provided with a ring passage 21b opened in the hole 21a. In the illustrated example, the same number of ring passages 21b as the ring grooves P3 of the piston P are provided at the same axial pitch as the ring grooves P3.

  The shutters 22 are provided at a plurality of locations (for example, four locations) at equal intervals in the circumferential direction along the inner peripheral surface of the hole 21 a of the main body portion 21. The shutter 22 can be moved up and down between a position (see FIGS. 1 and 2) that closes the opening of the ring groove P3 and a position (see FIG. 5) that is retracted below the ring groove P3.

  The stopper receiver 23 is provided below the stopper 13 of the piston holding part 10 and is provided at a position where it first contacts when the piston holding part 10 holding the piston P is lowered. In the illustrated example, a stopper receiver 23 is fixed to the upper surface of the main body 21. However, the present invention is not limited to this. For example, the stopper receiver 23 may be provided separately from the main body 21 via a frame or the like.

  Hereinafter, a method of assembling the piston ring R to the piston P by the piston ring assembling apparatus 1 will be described.

  The procedure for holding the piston P by the piston holding part 10 will be described with reference to FIG. First, as shown to Fig.3 (a), the piston holding | maintenance part 10 is arrange | positioned above the piston P mounted with the top surface P4 facing down. Then, as shown in FIG. 3B, the piston holding part 10 is lowered, and the rotation restricting part 12 is brought into contact with the end face (upper end face in the figure) of the skirt part P2 of the piston P. After that, as shown in FIG. 3C, the pair of arms 14 are moved in a direction approaching each other, and the pair of holding pins 11 are inserted into the pair of pin holes P1 of the piston P (see FIG. 1). At this time, by inserting the taper-shaped holding pin 11 until it is in close contact with the entire circumference of the opening of the pin hole P1, the holding pin 11 and the pin hole P1 Is centered. Thereby, piston P is hold | maintained in an exact position via pin hole P1. Further, in this state, the pair of rotation restricting portions 12 are in contact with the end face of the skirt portion P2 of the piston P (see FIG. 2), so that the rotation of the piston P around the pin hole P1 is restricted, and the piston P Furthermore, it is held at an accurate position (posture).

  The piston ring R is supplied to the ring holding unit 20 while the piston P is held by the piston holding unit 10 as described above. Specifically, the piston ring R cut out from a cutting device (not shown) is supplied to the vicinity of the hole 21a through the ring passage 21b. The piston ring R is expanded in diameter by a not-illustrated diameter expanding mechanism, and in this state, the shutter 22 is raised and inserted into the inner periphery of the piston ring R expanded in diameter. Thereafter, when the diameter expansion by the diameter expansion mechanism is released, the inner peripheral surface of the piston ring R comes into contact with the shutter 22, and thus the piston ring R is held in an expanded state (see FIGS. 1 and 2).

  Thereafter, the piston holding part 10 holding the piston P is moved horizontally, and the piston P and the piston ring R are arranged coaxially. In the present embodiment, the piston P held by the piston holding part 10 is coaxially arranged above the piston ring R whose diameter is held by the ring holding part 20 (see FIGS. 1 and 2). Thereafter, the piston holding portion 10 is lowered, and the piston P is inserted into the inner periphery of the piston ring R held in the expanded diameter state. Then, when the stopper 13 of the piston holding part 10 comes into contact with the stopper receiver 23 of the ring holding part 20 from above, the lowering of the piston holding part 10 is stopped. Thereby, the ring groove P3 of the piston P is positioned with respect to the piston ring R in the vertical direction. At this time, the top surface P4 of the piston P is not in contact with any surface. The term “on the same axis” as used herein refers to a state in which the central axes of the piston P and the piston ring R are aligned to the extent that the piston P and the piston ring R can be assembled. Not limited to cases.

  Thus, in this embodiment, positioning of the ring groove P3 with respect to the piston ring R is performed on the basis of the pin hole P1. Since the pin hole P1 and the ring groove P3 are both finished (for example, ground) and their vertical distances are set with high accuracy, the pin hole P1 is arranged at a predetermined height, so that the ring The groove P3 can be precisely arranged at the desired height, ie the same height as the piston ring R. In the present embodiment, the pin hole P1 and the holding pin 11 are centered, and the piston P is held at an accurate position by the piston holding part 10 with respect to the pin hole P1, so that the ring groove P3 is formed in the piston ring. It can be arranged accurately with the same height as R. In this way, by positioning the piston P with reference to the pin hole P1 instead of using the top surface P4 as a reference, the ring groove P3 of the piston P and the piston regardless of the surface accuracy and shape of the top surface P4. The height of the ring R can be matched.

  Moreover, in this embodiment, since the rotation control part 12 is made to contact | abut on the end surface of the skirt part P2 of piston P, rotation around the pin hole P1 of piston P is controlled. As a result, when the piston P is held by the holding pin 11 or when the piston P is held by the piston holding portion 10 and conveyed, the piston P rotates around the pin hole P1 and the ring groove P3 moves in the horizontal direction. Can be prevented. In particular, since the end surface of the skirt portion P2 is usually finished, the piston P is in a desired posture, that is, the ring groove P3 is horizontal by bringing the rotation restricting portion 12 into contact with this surface. Can be held in. In this state, by inserting the piston P into the inner periphery of the piston ring R held in a horizontal state by the ring holding portion 20, the height of the ring groove P3 and the piston ring R can be made to coincide with each other. In addition, since the vertical dimension of the ring groove P3 is slightly larger than the thickness of the piston ring R, "the height of the ring groove P3 and the piston ring R match" means that the piston ring R is in the vertical direction of the ring groove P3. A state that is completely contained in an area.

  Thereafter, as shown in FIG. 5, when the shutter 22 is lowered, the expansion of the piston ring R is released, and the piston ring R is elastically reduced in diameter and assembled in the ring groove P3 of the piston P. At this time, as described above, since the height of the ring groove P3 and the piston ring R coincide with each other in the entire circumference, the piston ring R is accurately assembled to the ring groove P3 without interfering with the outer peripheral surface of the piston P. It is done. Thus, the assembly of the piston ring R to the ring groove P3 of the piston P is completed.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the ring groove P3 of the piston P is positioned with respect to the piston ring R by bringing the stopper 13 of the piston holding part 10 and the stopper receiver 23 of the ring holding part 20 into contact with each other. For example, the ring groove P <b> 3 can be positioned with respect to the piston ring R by controlling the drive unit that lowers the piston holding unit 10.

  Further, in the above embodiment, the case where the rotation restricting portion 12 is provided in the piston holding portion 10 is shown. However, the ring groove P3 of the piston P is set to the height of the piston ring R in the entire circumference only by the holding pin 11. If it can be arranged, the rotation restricting portion 12 may be omitted.

  In the above embodiment, the holding pin 11 is formed in a taper shape to constitute a centering mechanism that performs centering with the pin hole P1, but the present invention is not limited to this. A centering mechanism can also be configured by enabling diameter expansion on the inner periphery of P1.

  In the above embodiment, the case where the ring holding portion 20 is fixed and the piston holding portion 10 is lowered is shown. On the contrary, the piston holding portion 10 is fixed and the ring holding portion 20 is raised. You may let them.

DESCRIPTION OF SYMBOLS 1 Piston ring assembling apparatus 10 Piston holding part 11 Holding pin 12 Rotation restricting part 13 Stopper 14 Arm 20 Ring holding part 21 Main part 21a Hole 21b Ring passage 22 Shutter P Piston P1 Pin hole P2 Skirt part P3 Ring groove P4 Top surface R piston ring

Claims (3)

A piston holding part that holds the piston by inserting a holding pin into a pair of pin holes provided in the piston, a ring holding part that holds the piston ring in an expanded state, and the piston and the piston ring are coaxial. A drive unit that moves the piston holding unit in the axial direction with respect to the ring holding unit,
A ring groove of the piston is formed with respect to the piston ring by causing the piston holding portion to move in the axial direction relative to the ring holding portion and inserting the piston into the inner periphery of the piston ring. A piston ring assembling device that positions and assembles the piston ring into the ring groove by releasing the expanded diameter state of the piston ring by the ring holding portion and reducing the diameter of the piston ring,
A piston ring assembling apparatus that positions the ring groove with respect to the piston ring with the pair of pin holes as a reference.   The piston ring assembling apparatus according to claim 1, wherein the piston holding portion is provided with a rotation restricting portion that comes into contact with an end face of the skirt portion of the piston in a state where the holding pin is inserted into the pin hole.   The piston holding part is provided with a stopper, the ring holding part is provided with a stopper receiver, and the stopper and the stopper receiver are contacted in the axial direction to position the ring groove with respect to the piston ring. The piston ring assembling apparatus according to 1.

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