JP2001289015A - Valve spring mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve spring mechanism capable of obtaining the stabilized valve operation while variously setting a load to be applied to a valve spring. SOLUTION: In a high engine speed area of an engine (figure A), the pressure oil is supplied to an oil reservoir 7 through a hydraulic control device 9, and since a valve guide 5 is pushed upward, resisting a valve spring 4, a set load to be applied to the valve spring 4 increases. When starting the engine or in a low engine speed area (figure B), the pressure oil is made to flow out from the oil reservoir 7, and as a result, the valve guide 5 is pushed down by the energizing force of the valve spring 4, and the set load to be applied to the valve spring 4 decreases. In this valve spring mechanism 1, since the valve guide 5 supports a valve stem 3a and while works as a spring seat of the valve spring 4, stabilized valve operation is obtained over the whole engine speed area including the time when staring the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve spring mechanism provided for an intake or exhaust valve of an engine.

[0002]

2. Description of the Related Art Conventionally, with respect to a valve spring mechanism provided in an intake or exhaust valve of an engine, a spring setting load is increased in order to prevent irregular movements such as jumps and bounces due to inertia of a valve system at a high engine speed. On the other hand, at low engine speeds, the set load is reduced to reduce energy loss and improve fuel economy. As a mechanism to achieve this,
Japanese Unexamined Utility Model Publication No. 5-64405 discloses a mechanism (FIG. 4). In this mechanism 100, a movable seat plate 103 is attached to one end of a spring 102 that urges an intake or exhaust valve 101 in a closing direction, and the movable seat plate 103 is moved into a hydraulic chamber 105 by a valve operation of a hydraulic valve 104. 4A, when the engine is in a low rotation range, the movable seat plate 103 comes into contact with the bottom of the hydraulic chamber 105 as shown in FIG. Spring 1
02, while the engine is in a high speed range, the movable seat plate 103 is pushed up by the hydraulic pressure supplied to the hydraulic chamber 105 as shown in FIG. Make it higher
A set load on the spring 102 according to each rotation range is obtained.

[0003]

However, the conventional valve spring mechanism has a structure in which the movable seat plate of the spring is supported only by hydraulic pressure, and is therefore constituted by the movable seat plate when the valve is operated. Since only one side of the spring seat becomes unstable due to sinking, there arises a problem that the operation of the valve becomes unstable. Further, in the above mechanism, the vibration of the spring accompanying the operation of the valve is easily transmitted to a hydraulic control device such as a hydraulic valve via a movable seat plate, and in some cases, a hydraulic system constituted by these devices is damaged. The problem arises.

[0004] It is an object of the present invention to provide a valve spring mechanism in which a set load of a valve spring is made variable and stable valve operation is obtained. It is another object of the present invention to provide a valve spring mechanism in which vibration of a spring accompanying the operation of a valve is hardly transmitted to a fluid pressure control device or the like. The object of the present invention is
Another object of the present invention is to provide a valve spring mechanism that enhances vortex flow in a combustion chamber.

[0005]

In order to solve the above-mentioned problems, a valve spring mechanism according to a first aspect of the present invention comprises:
A spring mechanism that includes a spring that urges the intake or exhaust valves of the engine in the closing direction. A valve guide that supports the valve stem of the intake or exhaust valve also serves as a spring seat at one end of the valve spring. In this way, the valve guide thus arranged is moved by a fluid pressure supplied through a fluid pressure control device such as a hydraulic pressure to vary a set load of the spring, and the valve guide is Since the support member of the valve stem of the intake or exhaust valve and the member (movable seat plate in the above example) constituting the spring seat of the valve spring are integrated, stable valve operation is achieved. Making it possible. Incidentally, it goes without saying that the set load of the spring varies depending on the rotation range of the engine. The valve spring mechanism according to claim 2 of the present invention is characterized in that the axial movement of the intake or exhaust valve of the valve guide is caused by the sliding between the helically provided valve guide and the uneven portion between the cylinder head and the cylinder head. It is based on Therefore, the manner of engagement between the two concavo-convex portions forms a structure that makes it difficult for the vibration of the spring accompanying the operation of the valve to be transmitted to the fluid pressure control device and the like. By the way, as the specific example, a screw mechanism having a trapezoidal or triangular cross section or a mechanism using a ball screw is suitable for the sliding between the two concavo-convex portions provided spirally. Further, the valve spring mechanism according to claim 3 of the present invention is configured such that the valve guide blocks a part of an intake passage provided in a cylinder head with movement of the valve guide. When the supply oil pressure is reduced (that is, in a low engine speed region, etc.), the valve guide is configured to block a part of the intake passage, thereby increasing the intake flow velocity and reducing the vortex in the combustion chamber. Can be strengthened.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve spring mechanism according to an embodiment of the present invention will be described with reference to FIGS. The valve spring mechanism 1 is disposed on an intake or exhaust valve (hereinafter, the intake valve 3 will be described in the present embodiment) of the cylinder head 2 and urges the intake valve 3 in a closing direction. In addition to the valve spring 4
A valve guide 5 that supports a valve stem 3 a forming a valve shaft of the intake valve 3 and also serves as a spring seat at one end of a valve spring 4 is provided. The valve guide 5 has a through hole 5d penetrating the center thereof, and the valve stem 3a inserted into the through hole 5d is supported by the valve guide 5 as described above. The uppermost end of the valve stem 3a contacts the intake cam 13 via the valve lifter 12, while a spring retainer 14 is mounted near the uppermost end. It has a spring seat. Also,
A mushroom-shaped valve element 3b is provided at the lowermost end of the valve stem 3a. The valve element 3b communicates the combustion chamber 15 with an intake passage 2d provided in the cylinder head 2 according to the operation of the valve 3. Let it go or get it out of the way.

The valve guide 5 according to the present invention includes a head member 5a having a convex cross section and a leg member 5b having a rectangular cross section. The upper surface of the head member 5a also serves as a spring seat at one end of the valve spring 4 as described above, together with the guide member 6 mounted on the upper portion. The head member 5a forms an oil (fluid) storage chamber 7 at a place surrounded by the lower surface and the large-diameter hole 2a of the cylinder head 2. The oil storage chamber 7 is provided with an oil pressure through an oil passage 8a. The ECU 11 is connected to a hydraulic control device 9 that supplies and discharges pressure oil of a pump 10 and is set by an engine speed.
The hydraulic control device 9 is operated in accordance with the control signal of
The pressure oil is supplied to the oil reservoir 7 through a. On the other hand, the leg member 5b moves in the small-diameter hole 2b connected to the large-diameter hole 2a. On the outer periphery of the leg member 5b, a spirally formed screw thread (convex portion) 5c is provided. Further, a screw groove (recess) 2c formed in a spiral shape is provided at a predetermined portion of the inner wall of the small diameter hole 2b corresponding to the screw thread 5c. The valve guide 5 rotates in the large-diameter hole 2a along the thread groove 2c of the small-diameter hole 2b by supplying and discharging the pressurized oil from the hydraulic control device 9 to the oil reservoir 7, thereby moving the valve guide 5 upward and downward (in FIG. 1). A or B direction)
The set load of the spring 4 can be varied as will be described later in detail.

Next, the operation of the present spring mechanism 1 will be described with reference to FIG. FIG. 2A is a state diagram in which the intake valve 3 is opened in a high engine speed range. When the engine speed shifts to the high speed range, E
The hydraulic control device 9 operates according to the control signal of the CU 11,
Pressure oil is supplied to the oil reservoir 7 through the oil passage 8a, and the valve guide 5 is pushed up in the direction A against the valve spring 4. As a result, the valve spring 4 contracts, so that the set load on the valve spring 4 increases,
Irregular movement due to the inertia of the valve is prevented, and the valve operation in a high rotation range is smooth. Moreover, the engagement state of the valve guide 5 with the cylinder head 2 is determined by the thread
Due to the connection between the thread grooves, the vibration of the valve spring 4 is not easily transmitted to the hydraulic system including the hydraulic control device 9 and the like via the head member 5a.

FIG. 1B is a state diagram in which the valve 3 is opened when the engine is started or in a low rotation range. In this case, as a result of the operation of the hydraulic control device 9 based on the control signal of the ECU 11, the pressure oil in the oil reservoir 7 flows out through the oil passages 8 a and 8 b, so that the valve guide 5 is moved in the B direction by the urging force of the valve spring 4. Depressed. As a result, the valve spring 4 extends, so that the set load on the valve spring 4 is reduced, energy loss is reduced, and fuel efficiency can be improved. In addition, since the engagement mode of the valve guide 5 with the cylinder head 2 is the connection between the thread and the thread groove as described above, the vibration of the valve spring 4 is controlled by the hydraulic control device 9.
It is difficult to transmit to hydraulic systems including In the valve spring mechanism 1, the valve guide 5 supports the valve stem 3a and also serves as a spring seat of the valve spring 4, so that the valve operation is stable over the entire rotation range including when the engine is started. Is possible.

Further, when the valve guide 5 is pushed down in the direction B, as shown in FIG. 3, when the leg member 5b is configured to block a part of the intake passage 2d, the intake passage 2d is closed. It is possible to increase the flow rate of the intake air from 2d to the combustion chamber 15, enhance the vortex in the combustion chamber 15, and stabilize the combustion.

In the present embodiment, the valve guide 5 is moved up and down by the supply of pressure oil from the hydraulic control device 9 to the oil reservoir 7 and the urging force of the valve spring 4.
The pressure may be increased or decreased by the hydraulic pump 10 instead of the urging force of the valve spring 4.

[0012]

According to the valve spring mechanism of the present invention, the set load of the valve spring can be made variable and stable valve operation can be obtained. Further, according to the valve spring mechanism of the present invention, the vibration of the spring accompanying the operation of the valve can be hardly transmitted to the fluid pressure control device or the like. Further, according to the valve spring mechanism of the present invention, in addition to the above-described effects, eddy currents in the combustion chamber can be promoted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of an intake valve including a valve spring mechanism according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view of the valve spring mechanism of FIG. 1;

FIG. 3 is an enlarged sectional view of the vicinity of an intake passage in FIG. 1;

FIG. 4 is an operation explanatory view of a conventional valve spring mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve spring mechanism 2 Cylinder head 2c Screw groove (recess) 2d Intake passage 3 Intake valve 3a Valve stem 4 Valve spring 5 Valve guide 5a Head member (spring seat) 5c Thread (convex) 9 Oil (fluid) pressure control apparatus

Claims (3)

[Claims] 1. A valve spring mechanism having a spring for urging an intake or exhaust valve of an engine in a closing direction thereof to support a valve stem of the valve and a spring seat at one end of the spring. A valve spring mechanism comprising a valve guide movably provided by a fluid pressure supplied via a fluid pressure control device. 2. The valve guide according to claim 1, wherein the movement of the valve guide in the axial direction of the valve is based on sliding between the concave and convex portions of the spirally provided valve guide and the cylinder head. The valve spring mechanism according to claim 1, wherein 3. The valve guide according to claim 1, wherein the valve guide blocks a part of an intake passage provided in a cylinder head as the valve guide moves.
3. The valve spring mechanism according to 1.