JP2008275093A - Seal structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a collision of a seal ring 24 against a side face of a ring groove 27. <P>SOLUTION: In a valve timing changing device of an internal combustion engine for changing the valve timing by fluid pressure in a fluid pressure chamber, a rotary body 15 is concentrically disposed on the outer periphery of a shaft body 17, and two fluid pressure passages for supplying an operating fluid to the fluid pressure chamber are respectively connected to annular passages 11B, 12B formed from inner passages of the shaft body 17 between the shaft body 17 and the rotary body 15. The seal ring 24 for partitioning the two annular passages 11B, 12B is interposed between the shaft body 17 and the rotary body 15. The axial dimension 33 of a groove side part 32 on the ring groove side entering the ring groove 27 forming a substantially rectangular cross section is set shorter than an axial dimension 35 of an opposite side part 34 of the groove of an opposite side of the ring groove 27. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a seal structure for a fluid pressure device that operates according to the fluid pressure of two fluid pressure chambers, such as a hydraulically driven valve timing changing device for an internal combustion engine.

  As described in Patent Document 1 and Patent Document 2, a valve timing changing device that changes the valve timing of an intake valve or an exhaust valve of an internal combustion engine receives hydraulic oil as a working fluid through two fluid pressure passages. According to the fluid pressure of the two fluid pressure chambers supplied, the valve timing is changed by changing the relative rotational position of the concentrically arranged rotating body and the outer rotating body outside of the rotating body. Yes.

The rotating body is disposed concentrically on the outer periphery of a substantially cylindrical shaft body (also referred to as a spider) formed integrally with a front cover of an internal combustion engine, for example, and each of the two fluid pressure passages is a shaft body. From the internal passage, the internal passage of the rotator is continued through an annular passage formed between the shaft body and the rotator. A seal ring that divides the annular passage of the two fluid pressure passages is interposed between the shaft body and the rotating body. The seal ring is mounted in a ring groove that is recessed in the outer peripheral surface of the shaft body.
JP 2001-59574 A JP 2004-143971 A

  During the operation of the internal combustion engine, an alternating load caused by combustion pressure, valve spring reaction force, etc. acts on the rotating body (or outer rotating body) from the camshaft side. The pressure of the cylinder fluctuates alternately under the influence of the alternating load. For this reason, in particular, in a seal ring disposed between the annular passages of the two fluid pressure passages, the ring groove moves axially in the ring groove due to the influence of pressure acting alternately from the two annular passages. Collision with the side surface of the tire will be repeated, and there are concerns about the occurrence of collision noise (sounding noise, abnormal noise) and wear of the seal ring due to the collision.

  In order to prevent such a movement of the seal ring in the ring groove in the axial direction, if the clearance between the seal ring and the ring groove is made small, the thermal expansion between the shaft body in which the ring groove is formed and the seal ring is performed. Variations in the gap due to the difference cannot be allowed or absorbed, and the degree of freedom in selecting a material such as a seal ring is reduced.

  Further, in the above-mentioned Patent Document 1, two seal rings are provided between the annular passages of the two fluid pressure passages with an intermediate chamber interposed therebetween. In this case, in order to prevent a collision between the seal ring and the ring groove. Although it is effective, it is still not sufficient, and there are problems such as an increase in the number of parts and a complicated structure and an increase in cost, and further improvement has been desired.

  The present invention has been made in view of such problems, and a main object of the present invention is to provide a novel seal structure capable of effectively preventing collision of the seal ring with the side surface of the ring groove.

  The seal structure of the present invention is applied to a fluid pressure device that operates according to the fluid pressures of two fluid pressure chambers to which a working fluid is supplied by two fluid pressure passages, respectively. Particularly preferred as such a fluid pressure device, the rotating body concentrically arranged in accordance with the fluid pressures of the two fluid pressure chambers to which the working fluid is supplied respectively by the two fluid pressure passages, and the outside of the outer side thereof This is a valve timing changing device for an internal combustion engine that changes the valve timing of an intake valve or an exhaust valve of the internal combustion engine by changing a relative rotational position with the rotating body.

  The rotating body is arranged concentrically on the outer periphery of a substantially cylindrical shaft body, and each of the two fluid pressure passages is an annular shape formed between the shaft body and the rotating body from the internal passage of the shaft body. It leads to the passage. A seal ring that divides the annular passage of the two fluid pressure passages is interposed between the shaft body and the rotating body, and is recessed in a substantially rectangular cross section on the outer peripheral surface of the shaft body or the inner peripheral surface of the rotating body. A ring groove is formed. In the seal ring, the axial dimension of the groove side on the ring groove side entering the ring groove is set shorter than the axial dimension of the anti-groove side part on the anti-ring groove side. In other words, at both corners near the ring groove on the groove side portion, damping portions recessed in a substantially L-shaped cross section are formed corresponding to the shape of the peripheral edge of the ring groove having a substantially L-shaped cross section. These damping portions make the groove side portion thinner in the axial direction than the anti-groove side portion.

  According to the present invention, the axial dimension of the groove side near the ring groove that enters the ring groove in the seal ring is shorter than the axial dimension of the anti-groove side on the side opposite to the ring groove that does not enter the ring groove. Therefore, a fluid reservoir having a predetermined volume can be formed between the side surface of the groove side portion and the side surface of the ring groove, that is, between the damping portion and the ring groove. Therefore, when the seal ring tries to move in the axial direction due to the pressure from one annular passage, the fluid pressure of the working fluid substantially enclosed in the fluid reservoir portion is opposed to the pressure from the annular passage side. A damping effect is obtained, and collision between the seal ring and the ring groove can be effectively avoided. In addition, the axial dimension of the groove side can be set sufficiently smaller than the axial dimension of the ring groove, and the change in the axial dimension due to the difference in thermal expansion between the seal ring and the ring groove is sufficiently allowed and absorbed. The degree of freedom of material selection is high.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 3 and 4 schematically show a hydraulically driven valve timing changing device 10 that changes the valve timing of an intake valve and an exhaust valve of an internal combustion engine as a fluid pressure device to which a seal structure according to the present invention is applied. ing. Such a valve timing changing device 10 itself is known as described in Japanese Patent Application Laid-Open No. 2001-59574, Japanese Patent Application Laid-Open No. 2004-143971, and the like, so only a brief description will be given here. FIG. 3 shows the overall configuration in a simplified manner, and the shape of the seal ring 24 that is characteristic of this embodiment is not drawn.

  This valve timing changing device 10 is provided in a power transmission path from a crankshaft, which is an output shaft of an internal combustion engine, to a camshaft 1 having a cam 2 that opens and closes an intake / exhaust valve, and is provided with two first fluid pressure paths. 11 and the second fluid pressure passage 12 are arranged concentrically according to the fluid pressures of the two first fluid pressure chambers 13 and the second fluid pressure chambers 14 to which the working fluid (working oil) is supplied, respectively. By changing the relative rotational position of the inner rotating body (rotating body) 15 and the outer rotating body 16 outside thereof, the rotational phase of the camshaft 1 is retarded / advanced to change the valve timing. Is. The outer rotator 16 rotates integrally with a sprocket or pulley to which rotational power is transmitted from the crankshaft via a chain or a belt, and the inner rotator 15 is fixed to the camshaft 1. Rotates integrally.

  As shown in FIG. 4, the inner rotator 15 is provided with a plurality of (four in this example) vanes 15B protruding outward in the radial direction from the shaft portion 15A. The formed recess 16A is liquid-tightly partitioned into the first and second fluid pressure chambers 13 and 14 described above. The vane 15B rotates and moves in the recess 16A according to the fluid pressure in the first and second fluid pressure chambers 13 and 14, whereby the relative rotational position of the inner rotator 15 and the outer rotator 16 changes. .

  As shown in FIG. 3, the cylindrical shaft portion 15 </ b> A of the inner rotating body 15 is disposed concentrically on the outer periphery of a columnar shaft body (also referred to as a spider) 17. In this embodiment, the shaft body 17 is integrally formed with the front cover 3 fixed to a cylinder head or the like of the internal combustion engine. Two fluid pressure passages 11 and 12 are formed using the shaft body 17. That is, the fluid pressure passages 11 and 12 are provided between the outer peripheral surface of the shaft body 17 and the inner peripheral surface of the shaft portion 15A of the inner rotary body 15 from the inner passages 11A and 12A formed inside the shaft body 17. The annular passages 11B and 12B are formed, and the internal passages 11C and 12C are formed inside the inner rotary body 15. Thus, by forming the two fluid pressure passages 11 and 12 using the shaft body 17 extending in the axial direction inside the inner rotating body 15, the fluid pressure passages 11 and 12 can be shortened or structured. Is simplified.

  The fluid pressure control valve 18 is a three-position switching type, and the both fluid pressure passages 11 and 12 are selectively communicated with the supply passage 20 from the oil pump 19 and the discharge passage 22 to the oil pan 21, respectively. As shown in the drawing, both fluid pressure passages 11 and 12 are blocked to maintain the fluid pressure in both fluid pressure chambers 13 and 14. The operation of the fluid pressure control valve 18 is controlled by the control unit 23 according to the engine operating state.

  And between the outer peripheral surface of the shaft body 17 and the inner peripheral surface of the shaft portion 15A of the inner rotator 15, the annular passages 11B and 12B of the two fluid pressure passages 11 and 12 are partitioned and partitioned in a liquid-tight manner. The two seal rings 24 (24A, 24B) of this embodiment are interposed, and an auxiliary seal ring 25 that partitions one of the first annular passages 11B and the atmosphere opening portion 26 that opens to the atmosphere is interposed. ing. In addition, a total of three ring grooves 27 (27A, 27B) and 28 are formed on the outer peripheral surface of the shaft body 17 and are recessed in a substantially rectangular cross section in which the seal rings 24 and 25 are mounted.

  FIG. 1 shows a cross-sectional shape of two seal rings 24 provided between both annular passages 11B and 12B. As shown in the figure, in this embodiment, two seal rings 24 (24A, 24B) are juxtaposed in the axial direction with the intermediate chamber 41 interposed between the annular passages 11B, 12B. Each seal ring 24 corresponds to the shape of the peripheral edge of the substantially L-shaped opening of the ring groove 27 having a substantially rectangular cross section at both corners near the ring groove 27 that will enter the ring groove 27. Damping portions 30 each having a substantially L-shaped cross section are formed. That is, each damping part 30 is bent at a substantially right angle from the side surface in the axial direction of the seal ring 24 to the inside of the ring, and has a circumferential surface 30A concentric with the inner and outer circumferential surfaces of the seal ring 24, and the seal ring The side surface 30B is bent at a substantially right angle from the inner peripheral surface of the seal ring 24 and forms a plane parallel to the side surface in the axial direction of the seal ring 24. In addition, such a damping part is not formed in the corner part near the anti-ring groove. Therefore, the axial dimension 33 of the groove side 32 on the ring groove side of each seal ring 24 is shorter than the axial dimension 35 of the anti-groove side 34 on the anti-ring groove side. That is, the groove side portion 32 is thinner in the axial direction (left-right direction in FIG. 1) than the anti-groove side portion 34, and the side surface of the groove side portion 32 constitutes the side surface 30B of the damping portion 30. The outer peripheral surface of the portion 34 constitutes the peripheral surface 30A of the damping portion 30. Further, the axial dimension 35 of the non-groove side portion 34 is set to be equal to or larger than the axial dimension 36 of the ring groove 27.

  The radial direction dimensions 37 and 38 of the non-groove side portion 34, that is, the dimensions 37 and 38 from the inner peripheral surface to the outer peripheral surface 30 A of the anti-groove side portion 34 are the clearance dimension 39 between the corresponding shaft body 17 and the rotary body 15. The size is set to be substantially the same as 40, and more specifically, a size slightly smaller by an amount corresponding to a minimum passage 43 described later. In this embodiment, the volume of the intermediate chamber 41 formed between the two seal rings 24 is ensured to be large, and the intended effect on the ring groove 27 of the seal ring 24 by the fluid pressure sealed in the intermediate chamber 41 is achieved. The clearance dimension 39 in the intermediate chamber 41 is set to be larger than the clearance dimension 40 in the annular passages 11B and 12B on both sides thereof, so that the anti-groove side portion is correspondingly obtained. The radial dimension 37 near the intermediate chamber 41 in 34 is set larger than the radial dimension 38 near the annular passages 11B and 12B. As a result, each seal ring 24 has an asymmetric cross-sectional shape on the inner peripheral side and the outer peripheral side, and both seal rings 24A and 24B have a substantially symmetric cross-sectional shape with the intermediate chamber 41 interposed therebetween.

  Referring to FIG. 2, (A) shows a seal ring 24 'of a comparative example having a substantially rectangular cross section, and (B) shows a seal ring 24 of this embodiment. Now, when the pressure F1 of the working fluid sealed in the first annular passage 11B side on the left side of the drawing due to the alternating load or the like described above acts on the seal ring 24 ', in the comparative example, the seal ring 24' Moves to the right, and the right side surface thereof strongly collides with the right inner surface of the ring groove 27.

  On the other hand, in this embodiment, since the axial dimension 33 of the groove side portion 32 is set shorter than the axial dimensions 35 and 36 of the anti-groove side portion 34 and the ring groove 27, the groove in the seal ring 24 is provided. Between the side portion 32 and the seal groove 27, there is a fluid reservoir portion 42 that is a space surrounded by a substantially rectangular cross section by the peripheral surface 30 </ b> A and the side surface 30 </ b> B of the damping portion 30 and the bottom surface and side surface of the seal groove 27. Is formed. Here, as described above, the radial dimensions 37 and 38 of the anti-groove side portion 34 are substantially the same as or slightly smaller than the corresponding gap dimensions 39 and 40 between the shaft body 17 and the rotating body 15. A portion where the fluid reservoir 42 communicates with the annular passages 11B, 12B or the intermediate chamber 41 becomes an orifice-like minimum passage 43 having a very small passage cross-sectional area, and the working fluid is satisfactorily sealed in the fluid reservoir 42. It becomes. Accordingly, as in the comparative example described above, when the seal ring 24 is moved to the right by receiving a pressure F1 stronger than the first annular passage 11B on the left side of the drawing, the fluid reservoir 42 on the right side is substantially The fluid pressure of the sealed working fluid becomes opposite to the pressure F1, so that a so-called damping effect is obtained, and the seal ring 24 moves to the right by the pressure F1, that is, the damping portion 30. As the side surface 30B approaches the side surface of the opposing ring groove 27, the minimum passage 43 becomes longer and its flow resistance increases. Therefore, it is possible to effectively avoid collision between the seal ring 24 and the ring groove 27. it can.

  Moreover, since the axial dimension 33 of the groove side portion 32 is set to be sufficiently smaller than the axial dimension 36 of the ring groove 27, the axial dimension due to the difference in thermal expansion between the seal ring 24 and the ring groove 27 or the like. The change can be allowed and absorbed with a margin, and the freedom of material selection is high.

  Further, as in the present embodiment, when two seal rings 24A and 24B are provided between two annular passages 11B and 12B with the intermediate chamber 41 interposed therebetween, the above-mentioned JP-A-2001-59574 is disclosed. Similar to the above, the collision between the seal ring 24 and the ring groove 27 caused by the alternating load can be reduced and avoided more reliably.

  However, in the present invention, the collision between the seal ring 24 and the ring groove 27 can be reduced and avoided by the damping effect in the fluid reservoir 42 described above, and therefore, for example, the oil ring 24 is provided between the two annular passages 11B and 12B. It is also possible to adopt a configuration in which only one is arranged (see FIG. 2B). In this case, the number of parts is smaller than in the above-described embodiment, and the configuration is simplified and the cost is reduced. Benefits are gained.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes without departing from the spirit of the present invention. . For example, the seal structure of the present invention is not limited to the valve timing changing device 10 of the above embodiment, but can be applied to various fluid pressure devices including a shaft body and a rotating body in which an internal passage of the fluid pressure passage is formed. .

Sectional drawing which expands and shows the principal part of FIG. 3 to which the seal structure which concerns on one Example of this invention was applied. Sectional drawing which shows the seal structure of a comparative example (A) and a present Example (B). 1 is a cross-sectional view schematically showing a valve timing changing device for an internal combustion engine to which a seal structure of the present embodiment is applied. Sectional drawing which shows the valve timing change apparatus of FIG.

Explanation of symbols

10 ... Valve timing changing device (fluid pressure equipment)
DESCRIPTION OF SYMBOLS 11, 12 ... Fluid pressure passage 11A, 12A ... Internal passage 11B, 12B ... Annular passage 13, 14 ... Fluid pressure chamber 15 ... Inner rotary body (rotary body)
16 ... Outer rotating body 17 ... Shaft body 24 (24A, 24B) ... Seal ring 27 (27A, 27B) ... Ring groove 30 ... Damping part 32 ... Groove side part 34 ... Anti-groove side part 41 ... Intermediate chamber 42 ... Fluid pool Part

Claims (5)

The relative rotational position of the concentrically arranged rotating body and the outer rotating body outside thereof is changed according to the fluid pressures of the two fluid pressure chambers to which the working fluid is supplied by the two fluid pressure passages, respectively. In the seal structure of the valve timing change device of the internal combustion engine for changing the valve timing of the intake valve or the exhaust valve of the internal combustion engine,
The rotating body is disposed concentrically on the outer periphery of a substantially cylindrical shaft body,
Each of the two fluid pressure passages is connected to an annular passage formed between the shaft body and the rotating body from the inner passage of the shaft body,
A seal ring that divides the annular passage of the two fluid pressure passages is interposed between the shaft body and the rotating body, and is recessed in a substantially rectangular cross section on the outer peripheral surface of the shaft body or the inner peripheral surface of the rotating body. Ring groove is formed,
The seal ring is characterized in that the axial dimension of the groove side on the ring groove side entering the ring groove is set shorter than the axial dimension of the anti-groove side part on the anti-ring groove side .   At both corners on the ring groove side of the groove side portion, corresponding to the shape of the opening peripheral edge portion having a substantially L-shaped cross-section of the ring groove, a damping portion recessed in a substantially L-shaped cross section is formed, respectively. The seal structure according to claim 1, wherein a fluid reservoir portion is formed between the damping portion and the ring groove.   The seal structure according to claim 1 or 2, wherein the two seal rings are provided between the annular passages of the two fluid pressure passages with the intermediate chamber interposed therebetween.   The seal according to any one of claims 1 to 3, wherein the anti-groove side portion is set to have substantially the same radial dimension as a gap dimension between a corresponding shaft body and a rotating body. Construction. In the seal structure of a fluid pressure device that operates according to the fluid pressure of two fluid pressure chambers to which the working fluid is supplied by two fluid pressure passages, respectively,
A rotating body is concentrically arranged on the outer periphery of a substantially cylindrical shaft body,
Each of the two fluid pressure passages is connected to an annular passage formed between the shaft body and the rotating body from the internal passage of the shaft body,
A seal ring that divides the annular passage of the two fluid pressure passages is interposed between the shaft body and the rotating body, and is recessed in a substantially rectangular cross section on the outer peripheral surface of the shaft body or the inner peripheral surface of the rotating body. Ring groove is formed,
The sealing ring has a damping portion that is recessed in a substantially L-shaped cross section corresponding to the shape of the peripheral edge portion of the ring groove having a substantially L-shaped cross section at both corners on the ring groove side that enters the ring groove. Are respectively formed.

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