JP2005248894A - Valve system for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably prevent slippage in an axial direction of a valve guide due to an increase in temperature and vibration during operation without sacrificing maintainability. <P>SOLUTION: An annular groove 8b in a radially recessed shape is formed in the outer periphery of the valve guide 8 protruding from the wall part of a cylinder head 1, and a radially protruding protrusion part 12c is formed on the inner diameter side of a half cotter mounted on the valve guide 8. The protrusion part 12c of the cotter 12 is fitted in the annular groove 8b of the valve guide 8, and by regulating movement in an axial direction of the valve guide 8 in a way that a seat surface part 2a of the cotter 12 is pressed by a valve spring 3, slippage in an axial direction of the valve guide due to temperature increase and vibration during operation is reliably prevented from occurring without sacrificing maintainability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine valve operating apparatus in which a valve body urged in a valve closing direction by a valve spring is slidably inserted into a valve guide fitted to a cylinder head.

  In general, an engine valve mechanism is configured such that a valve stem of an intake valve or an exhaust valve is slidably inserted into a valve guide fixed to a cylinder head, and is opened and closed by a cam or a rocker arm that contacts the stem end. have.

  In this case, the valve guide is generally formed of heat-resistant steel and is press-fitted and fixed to the cylinder head by a method such as room temperature or cold fitting, but the cylinder head is formed of aluminum alloy or the like. In this case, due to the temperature rise during operation, the press-fitting allowance is reduced due to the difference in coefficient of linear expansion between the materials, and vibration during operation may be added to loosen the valve guide and shift in the axial direction.

For this reason, for example, in Patent Document 1, when a convex portion or a concave portion is provided on the outer periphery of the valve guide and the valve guide is cast when the cylinder head is cast, the valve guide is fitted to the cylinder head by the convex portion or the concave portion. Thus, a technique for preventing the axial displacement of the valve guide is disclosed.
JP 2002-309998 A

  However, in the technique disclosed in Patent Document 1, since the valve guide is completely cast into the cylinder head, it is difficult to disassemble at the time of repair and inspection of the valve operating device, and the valve guide is worn and needs to be replaced. For example, a situation occurs in which the entire cylinder head must be replaced.

  The present invention has been made in view of the above circumstances, and is an engine that can reliably prevent the axial displacement of the valve guide caused by temperature rise or vibration during operation without sacrificing maintenance. It aims at providing a valve operating apparatus.

  In order to achieve the above object, an engine valve operating system according to the present invention includes a valve guide fitted to a cylinder head, in which a valve body urged in a valve closing direction by a valve spring is slidably inserted. In the valve operating apparatus, a deformed portion having a convex shape or a concave shape in the radial direction is provided on an outer peripheral surface of the end portion exposed from the fitting portion of the valve guide to the cylinder head to the valve spring side, A split cotter having a locking portion fitted to the deformed portion and a seat surface portion pressed by the valve spring is mounted on the end portion side of the valve guide.

  At this time, it is desirable that the split cotter is provided with a step portion that rises from the seat surface portion and is inserted into the inner diameter side of the valve spring.

  The valve operating apparatus for an engine according to the present invention can reliably prevent the displacement of the valve guide in the axial direction due to temperature rise or vibration during operation without sacrificing maintenance.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to an embodiment of the present invention. FIG. 1 is a cross-sectional view of a main part of a cylinder head of an engine, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  In FIG. 1, reference numeral 1 denotes an engine cylinder head. In this embodiment, a push rod 2 that abuts on a cam (not shown) and moves forward and backward, swings in contact with the push rod 2, and is moved by a valve spring 3. It has a valve operating mechanism mainly composed of an intake valve and a rocker arm 4 that open and close the exhaust valve as a valve body biased in the valve closing direction. In FIG. 1, the description will be made assuming that the configuration on the intake valve side of the cylinder head 1 is the same, but the same applies to the exhaust valve side. Hereinafter, the configuration on the intake side will be representatively described.

  Specifically, the intake port 6 that opens to the combustion chamber 5 is formed in the cylinder head 1, and the opening of the intake port 6 to the combustion chamber 5 is opened and closed by the intake valve 7. The intake valve 7 has a valve stem 7 a slidably inserted into a through hole 8 a of a valve guide 8 fitted to the wall portion of the cylinder head 1 on the intake port 6. A stem seal 9 made of a rubber material or the like is attached to an upper end portion of the valve guide 8 that protrudes from the fitting portion of the valve guide 8 to the cylinder head 1 and is exposed to the valve spring 3, and the stem seal 9 serves as a shaft of the valve stem 7 a. The outer periphery is elastically pressed and sealed.

  Further, a groove portion is provided in the stem end 7 b of the intake valve 7, and a spring retainer 11 is attached to the groove portion via a valve cotter (split ring) 10. On the wall surface of the cylinder head 1 facing the spring retainer 11, a cotter 12 that is attached to the outer periphery of the valve guide 8 and prevents the valve guide 8 from shifting in the axial direction is disposed. A valve spring 3 is disposed between the seat surface portion 12 a and the spring retainer 11.

  Then, the valve spring 3 pushes the valve head 7 c of the intake valve 7 against the valve seat 13 to close the intake port 6, and the upper end surface of the stem end 7 b swings against the rocker shaft 14 erected on the cylinder head 1. It abuts on one end of a rocker arm 4 that is supported movably. The rocker arm 4 is formed by pressing a sheet metal material or the like, and the push rod 2 is in contact with the other end.

  Here, the valve guide 8 is formed of heat-resistant steel or the like, and is press-fitted into the cylinder head 1 with a specified press-fitting allowance by a method such as normal temperature or cold fitting. However, when the cylinder head 1 is formed of an aluminum alloy or the like, the press-fitting allowance is reduced due to the difference in linear expansion coefficient between the materials due to the temperature rise during operation, and the valve guide 8 is also added due to vibration during operation. There is a possibility of loosening and shifting in the axial direction.

  Therefore, as described above, the cotter 12 for preventing the valve guide 8 from shifting in the axial direction is mounted on the outer periphery of the valve guide 8 protruding from the wall portion of the cylinder head 1. The cotter 12 is a split cotter composed of two members obtained by halving a ring-shaped member (see FIG. 2), and a step portion 12b that rises from the seat surface portion 12a and is inserted into the inner diameter side of the valve spring 3 is provided. A convex portion 12 c that protrudes in the radial direction is provided on the inner diameter side that is provided on the outer diameter side and is attached to the valve guide 8.

  Further, the outer peripheral surface of the end portion side that protrudes from the fitting portion of the cylinder head 1 of the valve guide 8 corresponding to the convex portion 12c of the cotter 12 has an annular shape as a deformed portion having a concave shape in the radial direction. A groove 8b is provided. A convex portion 12 c of the cotter 12 is fitted as an engaging portion in the annular groove 8 b of the valve guide 8, and the movement of the valve guide 8 in the axial direction is restricted by the urging force of the valve spring 3.

  The cotter 12 is assembled after the valve guide 8 is press-fitted into the cylinder head 1. Two halved members are mounted on the outer periphery of the valve guide 8, and the convex portion 12 c is fitted into the annular groove 8 b of the valve guide 8. Combine. Then, with the intake valve 7 and the stem seal 9 assembled, the valve spring 3 is set on the step portion 12b on the outer periphery of the cotter 12, thereby preventing the split cotter 12 from coming off and positioning the valve spring 3. Then, the spring retainer 11 is attached to the stem end 7 b of the intake valve 7 via the valve cotter 10.

  The valve guide 8 is press-fitted into the cylinder head 1, and the intake valve 7, the stem seal 9, the valve spring 3, the valve cotter 10, and the spring retainer 11 are assembled. 12 can also be assembled.

  Thereby, it is possible to reliably prevent axial displacement due to loosening of the valve guide 8 due to thermal expansion and vibration during engine operation. Moreover, since the split cotter 12 is engaged with the valve guide 8 and pressed in the axial direction by the urging force of the valve spring 3, disassembly / replacement becomes impossible by casting the valve guide into the cylinder head, etc. It is possible to reliably prevent the valve guide 8 from shifting in the axial direction while maintaining maintainability.

  In the present embodiment, the example in which the annular groove 8b is provided on the outer periphery of the valve guide 8 and the convex portion 12c is provided on the inner diameter side of the cotter 12 has been described, but conversely, the convex portion is provided on the outer periphery of the valve guide 8. An annular groove may be provided on the inner diameter side of the cotter 12.

Cross section of the main part of the engine cylinder head AA line sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 3 Valve spring 7 Intake valve 8 Valve guide 8b Annular groove 12 Cotter 12a Seat surface part 12b Step part 12c Convex part
Agent Patent Attorney Susumu Ito

Claims (2)

A valve operating device for an engine in which a valve body urged in a valve closing direction by a valve spring is slidably inserted into a valve guide fitted to a cylinder head,
On the outer peripheral surface of the end portion exposed from the fitting portion of the valve guide to the cylinder head on the valve spring side, a deformed portion that is convex or concave in the radial direction is provided,
A valve operating apparatus for an engine, wherein a split cotter having a locking portion fitted to the deformed portion and a seat surface portion pressed by the valve spring is mounted on the end portion side of the valve guide.   2. The valve operating apparatus for an engine according to claim 1, wherein the split cotter is provided with a step portion that rises from the seat surface portion and is inserted into an inner diameter side of the valve spring.

Images