JP2018132169A - Seal structure - Google Patents

Abstract

The sealing performance of a dust lip of an oil seal mounted between a boss portion of a crank pulley and a cover member of an engine block is impaired by vibration. An outer peripheral surface of a boss portion 17a of a crank pulley 17 to which a tip end portion of a crankshaft 10 is fitted, and an engine block 13 that rotatably supports the crankshaft, and the boss portion of the crank pulley is inserted. A fitting portion 22a that is disposed between the inner peripheral surface of the opening portion 20a of the cover member 20 and is fitted into the opening portion of the cover member, and a seal lip 22b and a dust lip that are in sliding contact with the boss portion of the crank pulley. The seal structure of the present invention using the oil seal 22 having 22c is formed on the outer peripheral surface of the boss portion of the crank pulley, and has a bottom surface 24a and a pair of side surfaces 24b, 24c facing each other across the bottom surface, The seal lip is in sliding contact with the bottom surface, and an annular groove 24 with which the dust lip is in sliding contact with one of the pair of side surfaces is provided. [Selection] Figure 3

Description

  The present invention provides an oil seal disposed between an outer peripheral surface of a boss portion of a crank pulley to which a tip end portion of a crankshaft is fitted and an inner peripheral surface of an opening portion of a cover member through which the boss portion is inserted. It relates to the seal structure used.

  In addition to the bearing, a seal member may be disposed between the rotating member and the fixed member that supports the rotating member. For example, between the outer peripheral surface of the boss portion of the crank pulley fitted to the tip end portion of the crankshaft and the inner peripheral surface of the opening of the cover member through which the boss portion is inserted, the engine oil to the outside An oil seal is provided to prevent leakage and at the same time prevent entry of dust from the outside. An example of such an oil seal is disclosed in Patent Document 1.

JP 2011-252567 A

  In the seal structure using the oil seal disclosed in Patent Document 1, usually, the seal lip of the oil seal is arranged at an outer periphery of the boss portion of the crank pulley at a predetermined pressure by a coil spring arranged so as to surround the oil seal. It is kept pressed against the surface. For this reason, the seal between the reel lip and the outer peripheral surface of the boss portion of the crank pulley is resistant to deformation in the thrust direction and radial direction caused by fluctuations in the torque of the crankshaft and vibrations generated while the vehicle is running. It is possible to reliably maintain sex. However, the dust lip rises from the outer peripheral surface of the boss portion of the crank pulley against the deformation in the radial direction described above, and there is a possibility that the sealing performance cannot be maintained.

  An object of the present invention is to provide a seal structure capable of maintaining the sealing performance of a dust lip of an oil seal even when the crank pulley is displaced in the radial direction due to vibration or the like.

  The seal structure according to the present invention is fixed to an outer peripheral surface of the boss portion of a crank pulley having a cylindrical boss portion into which a tip end portion of the crankshaft is fitted, and an engine block that rotatably supports the crankshaft. And a fitting portion that is arranged between the opening portion of the cover member in which an opening portion through which the boss portion of the crank pulley is inserted is formed and is fitted to the opening portion of the cover member; A seal structure using an oil seal having a seal lip and a dust lip slidably in contact with the boss portion of the crank pulley, formed on the outer peripheral surface of the boss portion of the crank pulley, and facing the bottom surface across the bottom surface A pair of side surfaces, wherein the seal lip is in sliding contact with the bottom surface, and an annular groove is provided in one of the pair of side surfaces with which the dust lip is in sliding contact. It is intended to.

  In the present invention, an annular groove having a bottom diameter smaller than the diameter of the boss portion of the crank pulley is formed in the boss portion of the crank pulley, and an oil seal dust lip is in sliding contact with one of a pair of side surfaces of the annular groove. When the oil seal and the crank pulley are relatively displaced in the radial direction, the dust lip is only displaced in the radial direction relative to the crank pulley while maintaining contact with one side surface of the oil seal, and the sealing state is maintained. Is done.

  According to the seal structure of the present invention, a dust lip is brought into sliding contact with one of the pair of side surfaces of the annular groove against the torque variation of the crankshaft and the deformation in the radial direction caused by the vibration generated during the traveling of the vehicle. It can continue and the sealing property can be maintained reliably.

  In addition, since it is possible to use an oil seal having a smaller diameter than the conventional one, the life of the oil seal can be extended as much as the sliding resistance against the boss portion of the crank pulley is reduced.

It is sectional drawing showing the principal part of one Embodiment of the seal structure by this invention in a fracture | rupture state. FIG. 2 is a three-dimensional projection view showing the crankshaft and each member attached to the crankshaft in the embodiment shown in FIG. 1 in an exploded state. FIG. 2 is a cross-sectional view in which the oil seal portion in the embodiment shown in FIG. 1 is extracted and enlarged, but the lower half of the oil seal is extracted in a broken state.

  An embodiment of a seal structure according to the present invention will be described in detail with reference to FIGS. However, the oil seal according to the present invention is not limited to such an embodiment, and can be applied to any device that needs to prevent leakage of liquid from the inside and prevent dust from entering from the outside. .

  FIG. 1 shows a cross-sectional structure of the front end portion of the engine to which the crank pulley according to the present embodiment is attached, FIG. 2 shows an exploded structure of the main part, and FIG. 3 shows an oil seal portion in FIG. Show. In the lower half of FIG. 3, only the crank pulley is extracted and shown in a broken state.

  The crankshaft 10 shown in FIG. 1 is rotatably supported by a cylinder block 13a via a bearing metal 12 by a main bearing cap 11. In the present embodiment, a half-moon key groove 10a is formed at the tip of the crankshaft 10, and a pair of sprockets 15 and 16 and a crank pulley 17 are fitted via a half-moon key 14 attached thereto. The pair of sprockets 15 and 16 and the crank pulley 17 are integrally connected to the crankshaft 10 by a bolt 19 that is screwed into a female screw portion 10 b formed at the tip of the crankshaft 10 via a washer 18.

  One sprocket 15 is wound with a timing chain (not shown) for rotating a camshaft (not shown) that opens and closes an intake / exhaust valve (not shown), and the other sprocket 16 is shown for driving an oil pump (not shown). A chain that does not work is wound.

  The crankcase 13b constitutes the engine block 13 together with a cylinder block 13a, a cylinder head (not shown) and the like, and a chain cover 20 as a cover member in the present invention is fixed to the engine block 13 together with the end cover 21. The chain cover 20 is formed with a circular opening 20a through which the boss 17a of the crank pulley 17 is inserted. A fitting portion 22a of an oil seal 22 described later is press-fitted into the inner peripheral surface of the opening 20a. Fixed in state.

  The crank pulley 17 has a cylindrical boss portion 17 a into which the tip end portion of the crankshaft 10 is fitted. A V-belt 23 for driving a compressor, a cooling water pump, an alternator and the like (not shown) is wound around the crank pulley 17 in the present embodiment provided with a damper function by the rubber-like elastic body 17b. An annular groove 24 for receiving a seal lip 22b and a dust lip 22c of an oil seal 22, which will be described later, is formed on the outer peripheral surface of the boss portion 17a of the crank pulley 17. The annular groove 24 has a bottom surface 24a and a pair of side surfaces 24b and 24c facing each other across the bottom surface 24a, and the diameter of the bottom surface 24a is smaller than the diameter of the boss portion 17a. The depth of the annular groove 24, that is, the height of the side surfaces 24 b and 24 c is set to be greater than the maximum relative displacement amount of the crank pulley 17 along the radial direction perpendicular to the rotation axis C of the crankshaft 10 with respect to the chain cover 20. It is preferable to do. The relative displacement of the crank pulley 17 with respect to the chain cover 20 occurs with vibrations of the engine and the vehicle.

  An oil seal 22 is disposed between the opening 20a formed in the above-described chain cover 20 and the annular groove 24 formed in the boss 17a of the crank pulley 17 that passes through the opening 20a. The oil seal 22 in the present embodiment includes a fitting portion 22a, a back face 22d, a labyrinth slip 22e, a dust lip 22c, a seal lip 22b, and an endless coil spring 25, but is not limited thereto. . The labyrinth slip 22e protrudes on the opposite side to the engine block 13 with respect to the back face 22d extending radially inward from the opposite side (left side in FIG. 3) of the fitting portion 22a having a cylindrical shape, It has a truncated cone shape with a larger diameter on the tip side. The dust lip 22c protrudes outward from the inner peripheral end of the back face 22d and slides into contact with the side surface 24c opposite to the engine block 13 of the annular groove 24 of the crank pulley 17 that rotates together with the crankshaft 10. It has a truncated cone shape. The seal lip 22b protrudes from the inner peripheral end of the back face 22d to the engine block 13 side (right side in FIG. 3), and slidably contacts the bottom surface 24a of the annular groove 24 of the crank pulley 17 that rotates together with the crankshaft 10. The endless coil spring 25 is mounted on the outer periphery of the seal lip 22b and urges it in the direction of diameter reduction so that the seal lip 22b is always pressed against the bottom surface 24a of the annular groove 24 with a substantially constant pressure. Thereby, even when the relative displacement of the crank pulley 17 along the radial direction with respect to the chain cover 20 occurs due to vibration of the engine or the vehicle, the sealing performance of the seal lip 22b is reliably maintained. .

  In addition, when relative displacement of the crank pulley 17 along the radial direction with respect to the chain cover 20 occurs due to vibration of the engine or the vehicle, the sliding contact position between the dust lip 22c and the side surface 24c of the annular groove 24 is in the radial direction. It will only shift. For this reason, it is possible to improve the sealing performance of the dust lip 22c more reliably than the conventional one. Moreover, since the annular groove 24 is formed in the boss portion 17a of the crank pulley 17, a smaller diameter than the conventional one in which the oil seal dust lip and the seal lip are brought into sliding contact with the boss portion 17a of the crank pulley 17 is provided. The oil seal 22 can be used. As a result, the life of the oil seal 22 can be extended as much as the sliding resistance of the crank pulley 17 with respect to the boss portion 17a is reduced.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiments are not intended to limit the present invention, and can be arbitrarily changed according to its use, purpose, and the like, including configurations not directly related to the present invention. Is.

DESCRIPTION OF SYMBOLS 10 Crankshaft 13 Engine block 17 Crank pulley 17a Boss part 20 Chain cover 20a Opening part 22 Oil seal 22a Fitting part 22b Seal lip 22c Dustrip 24 Annular groove 24a Bottom face 24b, 24c Side

Claims (1)

An outer peripheral surface of the boss portion of the crank pulley having a cylindrical boss portion to which a tip end portion of the crankshaft is fitted;
The crankshaft is fixed to an engine block that rotatably supports the crankshaft, and is disposed between an inner peripheral surface of the opening of the cover member formed with an opening through which the boss of the crank pulley is inserted, and A seal structure using an oil seal having a fitting portion fitted into an opening of a cover member, and a seal lip and a dust lip slidably in contact with the boss portion of the crank pulley,
Formed on the outer peripheral surface of the boss portion of the crank pulley, and having a bottom surface and a pair of side surfaces facing each other with the bottom surface interposed therebetween, the seal lip is in sliding contact with the bottom surface, and the dust lip is on one of the pair of side surfaces A seal structure characterized by comprising an annular groove in sliding contact.

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