JP6102338B2 - Engine valve gear - Google Patents

Description

  The present invention relates to a valve operating apparatus for an engine for vehicles or the like, and more particularly to a valve operating apparatus capable of switching a cam for opening and closing a valve, and belongs to the technical field of the valve operating apparatus for an engine.

  As a valve operating device for an engine, a plurality of cams having different nose shapes for one valve are provided, and by selecting a cam for opening / closing the valve from among these cams, the opening / closing amount of the intake / exhaust valve and the opening / closing valve are selected. There is known a system in which the timing can be switched according to the operating state of the engine.

  For example, in Patent Document 1, a camshaft includes a shaft portion and a cylindrical cam element portion that is spline-fitted on the shaft portion so as to be slidable in the axial direction. In addition, a plurality of cams having different nose shapes are provided adjacent to one valve, and a cam for opening and closing the valve is switched by sliding the cam element portion in the axial direction. Yes.

  In that case, in the valve operating apparatus of Patent Document 1, an end face cam is provided on the end face of the cam element portion, and is provided so as to be able to rush into and retract from the facing position of the end face cam. An operating member that pushes the cam element portion in the axial direction by being engaged is provided, and a cam switching operation is performed by operating the operating member with an actuator.

  A so-called detent mechanism is provided as a positioning mechanism at the fitting portion between the cam element portion and the camshaft so that the cam element portion is positioned at a predetermined position when the cam switching operation is performed.

  By the way, in an engine that employs the valve gear as described above, in order to reduce the overall length of the camshaft in order to make it more compact, the cam bearing portion that rotatably supports the camshaft and the cam bearing portion are close to each other. It is necessary to further narrow the distance from the cam element portion.

  However, in the conventional detent mechanism, in the case of a valve operating device that moves the cam element portion in the axial direction by the end face cam, especially when the cam is switched while the cam shaft rotates at a high speed, the moving speed of the cam element portion also increases. In other words, there is a risk that it will go too far in the axial direction from the predetermined positioning position and collide with the end face of the cam bearing portion. In this case, problems such as abnormal noise occur.

  Further, in the configuration in which each cam element portion is positioned by a single dedent mechanism, the urging force of the spring that pushes the dedent ball constituting the dedent mechanism acts on one point of the cam element portion. The support state of the cam element part fitted to the part becomes unbalanced in the axial direction, and there is a risk that the smooth movement of the cam element part in the axial direction may be hindered.

  Note that Patent Document 2 discloses a cam element portion that includes a dedent mechanism (locking device) and a pressing element that applies a spring urging force similar to that of the dedent mechanism at both ends of the cam element portion. However, since the valve operating device of Patent Document 2 is configured to move the cam element portion with the groove cam, even when the cam element portion is close to the cam bearing portion, the cam element portion and the end surface of the cam bearing portion are arranged. There is no collision problem.

US Patent Publication 2011 / 02226205A1 Special table 2011-524482 gazette

  Accordingly, a first object of the present invention is to reliably prevent the cam element portion from colliding with the end surface of the cam bearing portion at the time of switching the cam with a simple configuration.

  Moreover, this invention makes it the 2nd subject to stabilize the support balance of the cam element part fitted by the axial part.

  In order to solve the above-described problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is
A camshaft provided with a shaft portion and a cam element portion fitted to the shaft portion so as to rotate integrally with the shaft portion and move in the axial direction. A camshaft having a common base circle and two cam portions having different nose shapes adjacent to each other and an end face cam provided on one end face;
A cam bearing portion that supports the cam element portion so as to rotate and move in the axial direction;
An operating member that engages an end face cam of the cam element portion and moves the cam element portion away from the other end side; and an operating member that moves to an inoperative position retracted from the end face cam;
Is provided,
A valve operating apparatus for an engine, wherein the cam element for switching the valve can be switched by moving the cam element part between the first position and the second position on the shaft part,
A positioning mechanism for positioning the cam element portion at the first position and the second position is provided at a fitting portion between the cam element portion and the shaft portion,
The positioning mechanism is
A pressing member held on one of the cam element part or the shaft part;
An engagement portion that is provided on the other of the cam element portion or the shaft portion and in which the pressing member is accommodated by an urging force;
The engaging portion is
Two recesses arranged axially adjacent to each other and to which the pressing member is selectively engaged;
An inner inclined portion provided in each of the two recesses so that the ends are in contact with each other at the boundary between the two recesses ,
In each of the two recesses, the outer inclined portion is provided so as to be positioned on the outer side in the axial direction of the inner inclined portion, and an inclination angle with respect to the axial direction is larger than that of the inner inclined portion .
The end face cam includes a lift part protruding in an axial direction from an end face of the cam element part,
The lift amount of the lift portion is smaller than an axial distance required for the cam element portion to move from one of the first position and the second position to the other.

The invention according to claim 2 of the present application is
A camshaft provided with a shaft portion and a cam element portion fitted to the shaft portion so as to rotate integrally with the shaft portion and move in the axial direction. A camshaft having a common base circle and two cam portions different in shape of the nose portion provided adjacent to each other;
A cam bearing portion that supports the cam element portion so as to rotate and move in the axial direction;
Is provided,
A valve operating apparatus for an engine, wherein the cam element for switching the valve can be switched by moving the cam element part between the first position and the second position on the shaft part,
A positioning mechanism for positioning the cam element portion at the first position and the second position is provided at a fitting portion between the cam element portion and the shaft portion,
The positioning mechanism is
A pressing member held on one of the cam element part or the shaft part;
An engagement portion that is provided on the other of the cam element portion or the shaft portion and in which the pressing member is accommodated by an urging force;
The engaging portion is
Two recesses arranged axially adjacent to each other and to which the pressing member is selectively engaged;
An inner inclined portion provided in each of the two recesses so that the ends are in contact with each other at the boundary between the two recesses ,
In each of the two recesses, the outer inclined portion is provided so as to be positioned on the outer side in the axial direction of the inner inclined portion, and an inclination angle with respect to the axial direction is larger than that of the inner inclined portion .
By moving the cam element portion in the axial direction on the end surface of the cam element portion by engagement with a predetermined operation member, the pressing member reaches the boundary portion from a position engaged with one of the recesses. An end face cam that is moved in the axial direction relative to the engaging portion to a position is provided.

In the invention of claim 1 or claim 2, pre-Symbol positioning mechanism may be provided in a pair so as to be separated axially from each other. In this case, in the pair of positioning mechanisms, the urging direction phases of the pressing members as viewed from the axial direction preferably match each other.
Furthermore, a second positioning mechanism different from the positioning mechanism may be provided in the fitting portion between the cam element portion and the shaft portion so as to be spaced apart from the positioning mechanism in the axial direction. In this case, the second positioning mechanism is provided on a pressing member held on one of the cam element portion or the shaft portion and on the other of the cam element portion or the shaft portion, and the pressing member is stored by an urging force. It is preferable that an inclined portion having the same inclination angle as the outer inclined portion is provided at both end portions in the axial direction of the engaging portion of the second positioning mechanism.

  With the above configuration, according to the invention according to each claim of the present application, the following effects can be obtained.

According to the first and second aspects of the present invention, when the cam element portion moves in the axial direction between the first position and the second position, the pressing member of the positioning mechanism is at the engaging portion of the positioning mechanism. Engage from the engagement position with one of the two recesses provided adjacent to the axial direction to the engagement position with the other recess via the boundary between the two recesses Relative to the part in the axial direction. After the relative movement of the pressing member from the engagement position with the one recess to the position where the pressing member reaches the boundary between the two recesses, the inertial movement of the cam element and the press acting on the inner inclined portion of the other recess The cam element portion can be moved by utilizing the axial acceleration force generated by the biasing force of the member. Therefore, the lift amount of the end face cam in the axial direction may be smaller than the axial distance between the first position and the second position, thereby shortening the total length of the camshaft.

By the way, the conventional detent mechanism is a circumferential groove having an arc-shaped recess cross-sectional shape having a radius equal to or larger than the radius of the detent ball to which the engaging portion is biased and engaged. In general, it is formed shallower than the radius. That is, since the concave portion has a line-symmetric shape on the left and right sides in the axial direction, the axial force that the concave portion receives by the urging force is the same when it engages with either the left or right surface of the concave portion.
On the other hand, according to the first and second aspects of the invention, in the two recessed portions provided adjacent to each other in the axial direction in the engaging portion of the positioning mechanism, the outer inclined portion is inclined more than the inner inclined portion. When the pressing member engages with the inner inclined portion, the axial force that the engaging portion receives by the biasing force is relatively small when the pressing member engages with the outer inclined portion. The force received by the engaging portion is relatively large. Therefore, according to the third aspect of the invention, it is possible to achieve both of the two effects that the pressing member is less likely to be detached from the engaging portion and the switching of the cam portion is smoother than before.

According to the invention described in claim 3 and claim 4 , since the engaging portions of the pair of positioning mechanisms have inclined portions at both ends in the axial direction, the pressing members of these two positioning mechanisms are the inclined portions. Each cam element portion is pressed in the axial direction at two locations by the urging force of each pressing member applied to the inclined portion.

Therefore, rather than the configuration in which each cam element part is positioned by a single dedent mechanism, when the cam element part is moved in the axial direction by the end face cam, even if the cam part is switched during the high-speed rotation of the camshaft, It is possible to more reliably prevent the cam element portion from excessively passing in the axial direction from the predetermined positioning position and colliding with the end surface of the cam bearing portion. Therefore, according to the present invention, problems such as abnormal noise do not occur.

According to the third aspect of the present invention, the pair of positioning mechanisms are disposed in the fitting portion between the cam element portion and the shaft portion so as to be spaced apart from each other in the axial direction, thereby constituting the pair of positioning mechanisms. Since the pressing member is provided with the phases in the urging direction aligned, the cam element portion is supported by the pressing members of the two positioning mechanisms at two points having the same phase when viewed from the center of the shaft portion.

Therefore, the cam element portion fitted to the shaft portion is supported in a more balanced state in the axial direction than the configuration in which each cam element portion is positioned by a single dedent mechanism. In this case, the cam element portion can move smoothly in the axial direction with respect to the shaft portion.

According to the third aspect of the present invention, the engaging portions of the pair of positioning mechanisms are both provided so that the pressing member is selectively engaged, and two concave portions whose both sides are inclined portions are provided adjacent to each other. In addition, the two outer inclined portions positioned outside the two adjacent concave portions have a larger inclination angle with respect to the axial direction than the two inner inclined portions positioned inside the two adjacent concave portions. .

  Therefore, the pressing member accommodated in each recess is biased and engaged with the inner inclined portion and the outer inclined portion on both sides thereof, and the cam element portion is held at a predetermined position by the two positioning mechanisms. Therefore, the holding force of the cam element portion is improved compared to the mechanism that performs positioning with a single detent mechanism, and it is more reliable that the cam element portion is inadvertently moved in the axial direction except when the cam portion is switched. Can be prevented.

In the invention according to claim 4 , in the engaging portion of the second positioning mechanism, a space between the inclined portions provided at both end portions in the axial direction may be formed at a bottom portion substantially parallel to the axial direction.

In this case, when the cam portion is switched, the pressing member of the second positioning mechanism moves in the axial direction while contacting the bottom of the engaging portion, but does not have an inner inclined portion like the other positioning mechanism. Since the reaction force in the axial direction that prevents the movement of the cam element portion due to the pressing member urging the inclined portion does not occur, the cam element portion moves more smoothly to a predetermined position than the invention according to claim 3. Can be made.

1 is a side view showing a schematic configuration of an exhaust side valve operating apparatus according to an embodiment of the present invention. It is a front view of the same valve apparatus by the x direction arrow of FIG. It is an expanded sectional view by the y-y line of FIG. It is a side view which shows the state which the cam part which act | operates from the state of FIG. 1 switched. It is a single-piece | unit perspective view of a cam element part. FIG. FIG. It is sectional drawing by the AA line of FIG. It is an expanded sectional view which shows the engaging part of a cam element part. It is an expanded sectional view of the cam element part which shows operation | movement when switching the cam part which opens and closes a valve from a 2nd cam part to a 1st cam part. It is sectional drawing similar to FIG. 8 of a modification.

  Hereinafter, an embodiment of the present invention will be described by taking a valve operating device of a 4-cylinder, 4-valve DOHC engine as an example.

FIG. 1 shows a configuration on the exhaust side of the valve gear according to the present embodiment. A cylinder head (not shown) has two exhausts for each of the _first to _fourth cylinders 11 to ₁₄ , for a total of eight exhausts. Valves A ... A and return springs B ... B for urging these exhaust valves A ... A in the closing direction are provided, and the return springs are provided above the cylinder head via rocker arms C ... C. B ... A camshaft 2 for opening the exhaust valves A ... A against the urging force of B is provided.

This cam shaft 2 is provided with each cylinder 1 ₁ to 1 ₄ of the central vertical wall portion provided at a position 3 ... 3 and the cap member 4 ... 4 attached to the top of each vertical wall portion 3 ... 3 of the cylinder head The cam bearings 5... 5 that are configured are rotatably supported and are rotationally driven via a chain by a crankshaft (not shown).

The cam shaft 2 includes a shaft portion 10, is splined to the shaft portion 10, and rotates integrally with the shaft portion 10 and first to fourth cam elements 20 ₁ to which is movable in the axial direction is composed of 20 _4, these cam elements ₂₀ 1 to 20 ₄ is made to correspond to each cylinder ₁ 1 to 1 ₄ are arranged in rows on the shaft portion 10.

Then, five electromagnetic operating devices 30 ₁ to 30 ₅ for moving the respective cam element portions 20 _{1 to} 20 ₄ by predetermined strokes on the shaft portion 10 are provided, and the first cylinder ₁₁ side of the cylinder row is provided. as the front, the first control device 30 ₁ to the front end position of the gas cylinder row, first, second operation device 30 ₂ in the second cylinder between a position, the third operating unit to the second, between the third cylinder position 30 _3, third, fourth operation device 30 ₄ between the fourth cylinder position, the fifth operation device 30 ₅ is disposed at the rear end position of the cylinder row.

Each of these operating devices 30 ₁ to 30 ₅ includes a main body 31 and a pin portion 32 as an operating member that moves from an inoperative position retracted into the main body 31 to an operating position protruding from the main body 31 when energized. As shown in FIG. 2, the pin portion 32 is connected to the camshaft 2 at a predetermined angle (for example, about 30 °) from the opposite side of the cam follower C ′ in the rocker arm C across the camshaft 2 in the rotational direction X. In this embodiment, they are respectively attached to pedestal portions G ... G formed integrally with the cap members 4 ... 4 constituting the cam bearing portions 5 ... 5. ing.

Further, in order to position the axial movement of the operating device ₃₀ 1 to 30 each cam element according _{5 20} 1 20 ₄ at a predetermined two locations, first in FIG 3, the second cam element ₂₀ 1, 20 ₂ as shown by way of example, the fitting portion of the shaft portion 10 and the cam elements ₂₀ 1 to 20 _4, a positioning mechanism, the two detent mechanisms 40A, 40B are respectively provided.

These detent mechanisms 40A and 40B are disposed in a hole 41 formed in the radial direction from the outer peripheral surface of the shaft portion 10, a spring 42 accommodated in the hole 41, and an opening portion of the hole 41, and the spring Detent ball 43 urged by 42 to protrude radially outward from the outer peripheral surface of shaft portion 10 and two of them provided adjacent to the inner peripheral surface of cam element portions 20 _{1 to} 20 ₄ in the axial direction. is composed of a circumferential groove ₄₄ 1, 44 ₂ place, when the detent ball 43 is engaged with one of the circumferential grooves 44 _1, cam elements ₂₀ 1 to 20 ₄ is at the first position shown in FIG. 1, wherein when the detent ball 43 is engaged with the other of the circumferential groove 44 _2, cam elements 20 ₁ to 20 ₄ is at the second position shown in FIG. 4, and is positioned, respectively.

Here, as shown in FIG. 1, when the first to fourth cam elements ₂₀ 1 to 20 ₄ are positioned in the first position all the first cam element 20 ₁ in the rear, second cam element 20 ₂ in front, the third cam element 20 ₃ backward, the fourth cam element 20 ₄ is located forward, therefore, first, the opposing end faces of the second cam elements ₂₀ 1, 20 ₂ is close to each other and, second, opposed end surface of the third cam elements ₂₀ 2, 20 ₃ is spaced apart from each other, third, opposing end surface of the fourth cam elements ₂₀ 3, 20 ₄ are brought close to each other.

Further, as shown in FIG. 4, when the first to fourth cam elements ₂₀ 1 to 20 ₄ are located in all the second position, the first cam element 20 ₁ in front, the second cam element 20 ₂ in the rear, third cam element 20 ₃ forward, fourth cam element 20 ₄ is located in the rear, thus, spaced first and opposing end surface of the second cam elements ₂₀ 1, 20 ₂ mutually The opposing end surfaces of the second and third cam element portions 20 ₂ and 20 ₃ are close to each other, and the opposing end surfaces of the third and fourth cam element portions 20 ₃ and 20 ₄ are in a state of being separated from each other.

Next, FIGS. 5 to 9, the configuration of the cam elements ₂₀ 1 to 20 _4, a first example cam element 20 ₁ will be described in more detail.

The cam element portion 20 ₁ (20 _{2 to} 20 ₄ ) has a cylindrical shape, and the outer peripheral surface of the intermediate portion is a journal portion 21 supported by the cam bearing portion 5, and the cylinder is provided on both sides of the front and rear sides. 1 ₁ to 1 ₄ of the two exhaust valves a, actuating unit 22 is provided for a, each actuating portion 22, for example, the lift amount for the time of low engine rotation is smaller first cam portion 22 _1, for example, the lift amount for the time of high engine speed and a larger second cam portion 22 ₂ is provided to be adjacent.

As shown in FIG. 7, the first cam portion 22 ₁ and the second cam portion 22 ₂ have a common base circle a and phased nose portions b ₁ and b ₂ having different lift amounts on the base circle a. Are provided. Then, this first cam portion 22 ₁ and ₂ the second cam portion 22, the two actuation portions 22, respectively by matching the order and nose portion _b 1, _{b 2} of the phase aligned in the longitudinal direction Is provided.

In that case, as shown in FIGS. 1 and 4, in the first cam element 20 ₁ and the third cam element 20 _3, the first cam portion 22 ₁ is the front, the second cam portion 22 ₂ is rearward is disposed in the second cam element 20 ₂ and the fourth cam element 20 _{4, 2} second cam portion 22 forwardly, ₁ first cam portion 22 is disposed in the rear.

When the cam element portions 20 _{1 to} 20 ₄ are positioned at the first position on the shaft portion 10 by the detent mechanism 40, the two first cam portions are included in any of the cam element portions 20 _{1 to} 20 ₄ . 22 _1, 22 ₁ are two rocker arms C of the corresponding cylinder ₁ 1 to 1 _4, the cam follower of the C C ', C' and the corresponding position (see FIG. 1), is positioned at the second position on the shaft portion 10 At this time, the second cam portions 22 ₂ and 22 ₂ are set so as to correspond to the cam followers C ′ and C ′ (see FIG. 4).

The engine according to this embodiment, the firing order of the cylinders, the first cylinder 1 ₁ → third cylinder 1 ₃ → the fourth cylinder 1 ₄ → are the second cylinder 1 _2, the cam elements 20 ₁ to 20 nose portion _b 1 of the first cam portion 22 ₁ and the second cam portion 22 ₂ of the _{4, b 2} are each 90 ° rotation of the cam shaft 2, corresponding to the cam followers C ', C' in this order The first to fourth cam element portions 20 _{1 to} 20 ₄ are spline-fitted to the shaft portion 10 with a phase difference so as to be positioned.

Further, to the each cam elements ₂₀ 1 to 20 _4, the end face cam 23 in both front and rear ends are respectively provided.

As shown in FIGS. 5 to 7, the front and rear end face cams 23, 23 are axially forward from the reference plane c with respect to a cross section passing through the axial center of the cam element portion 20 ₁ (20 _{2 to} 20 ₄ ). Alternatively, as shown in FIG. 7, the rotation portion X has a lift portion d that protrudes symmetrically rearward, and within a predetermined angle range θ (for example, about 120 °) from the lift start position e to the lift end position f. On the other hand, the lift amount in the axial direction gradually increases from the reference plane c, and returns to the reference plane c at the lift end position f.

Also, as described above, that each cam elements 20 ₁ to 20 ₄ is engaged respectively splined to the shaft portion 10 with a predetermined phase difference in accordance with the firing order of the cylinders 1 ₁ to 1 ₄ Accordingly, the end face cams 23 and 23 of the cam element portions 20 _{1 to} 20 ₄ facing each other are also opposed to each other with a phase difference, and as a result, adjacent to each other as shown by reference numerals a and b in FIG. 1 and reference numeral c in FIG. When the cam element portions 20 _{1 to} 20 _{4 to be} moved approach each other, the lift portions d and d of the facing end face cams 23 and 23 overlap in the axial direction.

Then, the pin portion 32 ... 32 of the second to fourth operation device ₃₀ 2-30 _4, the lift portion d of the end cam 23, which face each other, of the two corresponding cam elements ₂₀ 1 to 20 _4, d Projecting to the operating position in an overlapping state and engaging with these end face cams 23, 23, the two cam element portions 20 _{1 to} 20 ₄ which are in close proximity to each other are rotated according to the rotation of the cam shaft 2. It is made to slide in the direction to separate.

At this time, in the state shown in FIG. 1, the first and second cam element portions 20 ₁ and 20 ₂ and the third and fourth cam element portions 20 ₃ and 20 _{4 that} are close to each other are separated from each other. both were moved to the second position shown in FIG. 4 from the first position, and in the state shown in FIG. 4, the second was close, the third cam elements 20 _2, 20 _3, by spaced apart from each other Move from the second position to the first position shown in FIG.

Meanwhile, the first operation device 30 ₁ of the pin portion 32, as shown in FIG. 4, the first cam element 20 ₁ is in the state in the second position of the front, first the front of the cam element 20 ₁ engages the end face cam 23 by projecting to the operating position facing the end face cam 23 according to the rotation of the cam shaft 2, moves the first cam element 20 ₁ to the first position of the rear. Similarly, the pin portion 32 of the fifth operation device 30 _5, the fourth cam element 20 ₄ in a state where the second position of the rear, facing the fourth cam element 20 ₄ of the rear end face cam 23 By projecting to the operating position, the end face cam 23 is engaged and moved to the first rear position.

Here, in the first and fifth operating devices 30 ₁ and 30 ₅ , the protrusions of the operating devices 30 ₁ to 30 ₅ to the operating positions of the pin portions 32 are at the directing positions of the pin portions 32 and 32, respectively. reference plane c of the first cam element 20 ₁ of the front end face cam 23 or the fourth cam element 20 ₄ of the rear end face cam 23 is performed with a timing at which the position, the second to fourth operation device ₃₀ 2-30 ₄ must be performed at the timing when both reference surfaces c, c of the two end face cams 23, 23 facing each other are located at the directing positions of the pin portions 32... 32.

Also, the movement of each cam elements ₂₀ 1 to 20 ₄ by projecting into the working position of the pin 32, the cam follower C 'of the rocker arm C is in the first cam portion 22 ₁ and the second cam portion 22 ₂ base circle a timing corresponding positions are in, i.e., the cylinder 1 ₁ to 1 ₄ must be made when in the stroke other than the exhaust stroke.

Therefore, in order to satisfy these operating timing conditions, in this embodiment, as shown in FIG. 7, the tops of the nose parts b ₁ and b ₂ of the first and second cam parts 22 ₁ and 22 ₂ are used. The lift start position e of the end face cam 23 is set at a predetermined angle position on the front side in the rotational direction X, and the lift end position f of the end face cam 23 is set at a predetermined angle position on the rear side in the rotation direction X. The nose parts b ₁ , b _{2 of} the second cam parts 22 ₁ , 22 ₂ and the lift part d of the end face cam 23 are provided in a positional relationship. In this case, the positional relationship between the pin portion 32 of the cam follower C 'and the operating device ₃₀ 1 to 30 ₅ of the rocker arm C shown in FIG. 2, the cam elements ₂₀ 1 to 20 _4, to move immediately after the end of the exhaust stroke become.

8 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 8, a spline groove 51 that is spline-fitted to the shaft portion 10 is provided in the axial central portion of the inner peripheral surface of the cylindrical cam element portion 20 ₁ (20 _{2 to} 20 ₄ ). At the both ends of the spline groove 51, two circumferential grooves 44 ₁ and 44 ₂ for selectively engaging the detent balls 43 are provided adjacent to each other in the axial direction.

Figure 9 is an enlarged sectional view of the circumferential groove ₄₄ 1, 44 ₂ constituting the first detent mechanism 40A in the cam elements ₂₀ 1 to 20 ₄ of FIG. As shown in FIG. 9, the axial cross sections of the circumferential grooves 44 ₁ and 44 ₂ have substantially V-shaped concave shapes in which both sides are inclined portions 44 _1a , 44 _2a , 44 _1b , and 44 _2b . .

These inclined portions 44 _1a , 44 _2a , 44 _1b , and 44 _2b have inclination angles γ and δ with respect to the axial direction of the two outer inclined portions 44 _1b and 44 _2b located outside the adjacent circumferential grooves 44 ₁ and 44 _{2. Are} formed so as to be larger than the inclination angles α and β of the two inner inclined portions 44 _1a and 44 _2a located inside the adjacent circumferential grooves 44 ₁ and 44 ₂ . Further, the circumferential grooves 44 ₁ and 44 ₂ are formed so that the axial cross sections thereof are line-symmetric with each other, and have a relationship of inclination angles α = β and γ = δ.

Although the circumferential grooves 44 ₁ and 44 ₂ constituting the first detent mechanism 40A have been described as an example, in this embodiment, the circumferential grooves 44 ₁ and 44 ₂ constituting the second detent mechanism 40B have the same configuration. .

Next, referring to FIG. 10, the operation of the first detent mechanism 40A when moved to the first position the cam element 20 ₁ from the second position.

First, when the cam element 20 ₁ is in the second position, as shown in FIG. 10 (a), the detent ball 43 which is accommodated in a circumferential groove 44 ₂ by the urging force of the spring 42, both sides in the axial direction The second inner inclined portion _442a and the second outer inclined portion _442b are biased and engaged with each other and are positioned in the axial direction.

Here, the first operation device 30 ₁ of the pin portion 32 is protruded to the working position, the cam element 20 ₁ toward the first position (to the left in the figure) is moved, in FIG. 10 (b) as shown, since the detent ball 43 is (downward in the drawing) pressing the shaft section 10 side while in contact only with the second inner inclined portion 44 _2a, with the detent ball 43 toward the cam element 20 ₁ The urging spring 42 is compressed.

Thereafter, 10 as shown in (c), reaches a position detent ball 43 is the end portions of the circumferential groove 44 of the _second inner inclined portion _{44 1a} and the circumferential groove 44 of the _first inner inclined portion _{44 1a} contact when the moves the first operating device 30 ₁ of the pin portion 32 to an inoperative position retracted from the end face cam 23. At this time, the spring 42 is in the most compressed state.

Here, even after moving the first control device 30 ₁ of the pin portion 32 in the inoperative position, cam element 20 ₁ is further moved toward the first position by the inertia force, finally, FIG. 10 (d) as shown in, the detent ball 43 is in contact with the first inner inclined portion _{44 1a} of the circumferential groove 44 _1. At this time, the first inner inclined portion _441a is pressed in the axial direction (leftward in the drawing) by the restoring force of the compressed spring 42 to return to the natural length, so that the _first of the cam element 201 Movement to position is accelerated.

Thereafter, as shown in FIG. 10 (e), the detent ball 43 is temporarily engaged with the first inner inclined portion _{44 1a} and the first outer inclined portion _{44 1b} are inclined portion on either side of the circumferential groove 44 _1.

However, the cam element 20 continues to move by inertia force, as shown in FIG. 10 (f), the detent ball 43 engages only the first outer inclined portion _{44 1b} of the circumferential groove 44 _1. At this time, the cam element portion 20 is decelerated in the axial direction by the urging force of the spring 42, and eventually stops before the detent ball 43 is detached from the first outer inclined portion _441b .

Finally, cam element 20 by the urging force of the spring 42 back in the opposite direction (rightward in the drawing), as shown in FIG. 10 (e), the first detent ball 43 is located on each side of the peripheral groove 44 ₁ The inner inclined portion 44 _1a and the first outer inclined portion 44 _1b are held in a biased engagement. At this time, cam element 20 ₁ is positioned at the first position is a desired position.

Above, in this embodiment, FIG as shown in 10 (c), the detent ball 43 is the end of the circumferential groove 44 of the _second inner inclined portion _{44 1a} and the circumferential groove 44 of the _first inner inclined portion _{44 1a} together after reaching the contact position, cam element 20 which is moved by an inertial force while coming into contact with the first inner inclined portion 44 _1a of the circumferential groove 44 ₁ is accelerated in the axial direction by the biasing force of the spring 42, eventually the desired The cam element portion 20 can move to the first position. Therefore, while moving the pin portion 32 to the operative position, the detent ball 43 is the end portions of the circumferential groove 44 of the _second inner inclined portion _{44 1a} and the circumferential groove 44 of the _first inner inclined portion _{44 1a} may be formed end face cam 23 as cam element 20 ₁ is moved to contact position.

Therefore, according to this embodiment, as shown in FIG. 10 (e), to move the cam element 20 ₁ pin portion 32 is operated continuously until the cam element 20 ₁ reaches the first position Thus, since the lift amount of the end face cam 23 can be made smaller than when the end face cam 23 is formed, the overall length of the camshaft 2 can be further shortened.

Further, after retracting the pin 32 from the end face cam 23, because it is configured to position the cam element 20 ₁ in the desired position by the restoring force of the spring 42, cam element 20 ₁ is first and the pin portion 32 is operated continuously until reaching the position than to form the end face cam 23 to move the cam element 20 _1, the axial direction of the design size such as end cam 23 of the cam element 20 ₁ A greater tolerance can be specified for.

Although described as an example the operation of the first detent mechanism 40A when moved to the first position the cam element 20 ₁ from the second position, in this embodiment, the second detent mechanism 40B is first detent mechanism Since it has the same configuration as 40A, the second detent mechanism 40B operates in the same manner as the first detent mechanism 40A. Also, for the case of the other cam element ₂₀ 2 to 20 ₄ is also the case of moving the cam elements ₂₀ 1 to 20 ₄ from the first position to the second position also, the pin of the operating device ₃₀ 1 to 30 ₅ By moving the part 32 in the same manner, the detent mechanisms 40A and 40B operate similarly.

  Next, a modification of the cam element portion 20 of FIG. 8 will be described with reference to FIG.

As shown in FIG. 11, the cam element portion 20 ′ which is the modified example is different from the embodiment shown in FIG. 8 in the circumferential grooves 44 ₁ and 44 ₂ constituting the second detent mechanism 40 </ b> B as the second positioning mechanism. Only the shape of the inner peripheral surface of the part corresponding to is different.

That is, the cam element portion 20 ′ has the circumferential grooves 44 ₁ and 44 ₂ constituting the first detent mechanism 40A similar to the above-described embodiment as the first positioning mechanism, and as the engaging portion of the second positioning mechanism, the first position and substantially parallel to the bottom 44 _3C axially extending between the second position, the concave shape of the circumferential consisting of an outer inclined portion 44 _3a, 44 _3b provided at both ends of the bottom portion 44 _3C It comprises a groove 44 _3. The inclination angles of the outer inclined portions 44 _3a and 44 _3b with respect to the axial direction are the same as those of the outer inclined portions 44 _1b and 44 _{2b of} the circumferential grooves 44 ₁ and 44 ₂ constituting the first detent mechanism 40A.

As described above, according to the modification of the present embodiment, the engaging portion of the second positioning mechanism is formed on the bottom portion _443C substantially parallel to the axial direction between the outer inclined portions _443a and _443b. 22, the detent ball 43 of the second positioning mechanism moves in the axial direction while contacting the bottom portion _443C , but does not have the inner inclined portions 44 _1a and 44 _2a unlike the first positioning mechanism described above. Therefore, the detent ball 43 urges the inner inclined portions 44 _1a and 44 _2a to prevent an axial reaction force that hinders the movement of the cam element portion 20, so that the cam element portion is compared with the previous embodiment. 20 can be moved to a predetermined position more smoothly.

  Note that the present invention is not limited to the illustrated embodiment and its modifications, and it goes without saying that various improvements and design changes are possible without departing from the scope of the present invention.

  For example, in the above description, the shaft member 10 is provided with the pressing member made of the detent ball 43 and the like, and the cam element portion 20 is provided with the engaging portion made of the circumferential groove 44. An engaging portion may be provided at 20 and a pressing member may be provided at the shaft portion 10.

  In addition, the pressing member of the illustrated embodiment and its modified example is composed of the detent ball 43 and the spring 42, but is not limited to the spherical detent ball 43, and is a convex member that engages with the engaging portion. Any shape can be used. Further, the convex member and the biasing member that biases the convex member in the same manner as the spring 42 may be composed of separate parts as described above, but may be composed of an integral part. It may be. Further, the engaging portion is not limited to the circumferential groove 44 provided on the entire circumference of the inner peripheral surface or the outer peripheral surface, and may have a configuration in which a concave shape is provided in a predetermined phase.

  In the above embodiment, the camshaft 2 on the exhaust side is used. However, the camshaft 2 on the intake side can be configured in exactly the same manner, and the above-described effects can be obtained on the intake side.

Further, the cam elements ₂₀ 1 to 20 _4, the first small lift amount of the cam portion 22 ₁ has been increased second lift amount of the cam portion 22 _2, may be the other way round, further, the one with _'the conventional nose portion b _1' cam portion 22 1 provided, the other cam portion 22 2 _'nose b _2' the whole by eliminating formed only in the base circle a in (nose b _{2 '} The lift amount may be 0), and the valve may not be opened and closed when this cam portion 22 ₂ ′ is used. According to this, reduced-cylinder operation is possible at the time of low load operation of the engine.

  Further, the present invention is not limited to the four-cylinder four-valve DOHC engine shown in the above-described embodiment, but is applied to various engines having different numbers of cylinders and valve actuation types, including in-line six-cylinder engines and V-type multi-cylinder engines. Is possible.

  As described above, according to the present invention, in a valve operating apparatus for an engine capable of switching a cam that opens and closes a valve, it is easy for the cam element portion to collide with the end surface of the cam bearing portion when the cam is switched. Since it can be surely prevented by the configuration, it is suitably used in the manufacturing technical field of this type of engine.

2 cam shaft 5 cam bearing portion 10 shaft portion 20 _{1 to} 20 ₄ cam element portions 22 ₁ , 22 ₂ first and second cam portions (cam portions)
23 End face cam 32 Pin part (operation member)
40A First detent mechanism (first positioning mechanism)
40B Second detent mechanism (second positioning mechanism)
42 Spring (pressing member)
43 Detent ball (pressing member)
44 ₁ , 44 ₂ , 44 ₃ circumferential grooves (recesses, engaging portions)
44 _1a , 44 _2a Inner inclined portion 44 _1b , 44 _2b Outer inclined portion 44 _3a , 44 _3b Outer inclined portion (inclined portion)
44 _3c Bottom A Exhaust valve (valve)
α, β, γ, δ Inclination angle b ₁ , b ₂ nose part

Claims (4)

A camshaft provided with a shaft portion and a cam element portion fitted to the shaft portion so as to rotate integrally with the shaft portion and move in the axial direction. A camshaft having a common base circle and two cam portions having different nose shapes adjacent to each other and an end face cam provided on one end face;
A cam bearing portion that supports the cam element portion so as to rotate and move in the axial direction;
An operating member that engages an end face cam of the cam element portion and moves the cam element portion away from the other end side; and an operating member that moves to an inoperative position retracted from the end face cam;
Is provided,
A valve operating apparatus for an engine, wherein the cam element for switching the valve can be switched by moving the cam element part between the first position and the second position on the shaft part,
A positioning mechanism for positioning the cam element portion at the first position and the second position is provided at a fitting portion between the cam element portion and the shaft portion,
The positioning mechanism is
A pressing member held on one of the cam element part or the shaft part;
An engagement portion that is provided on the other of the cam element portion or the shaft portion and in which the pressing member is accommodated by an urging force;
The engaging portion is
Two recesses arranged axially adjacent to each other and to which the pressing member is selectively engaged;
An inner inclined portion provided in each of the two recesses so that the ends are in contact with each other at the boundary between the two recesses ,
In each of the two recesses, the outer inclined portion is provided so as to be positioned on the outer side in the axial direction of the inner inclined portion, and an inclination angle with respect to the axial direction is larger than that of the inner inclined portion .
The end face cam includes a lift part protruding in an axial direction from an end face of the cam element part,
The lift valve of the engine is characterized in that a lift amount of the lift part is smaller than an axial distance required for the cam element part to move from one of the first position and the second position to the other. A camshaft provided with a shaft portion and a cam element portion fitted to the shaft portion so as to rotate integrally with the shaft portion and move in the axial direction. A camshaft having a common base circle and two cam portions different in shape of the nose portion provided adjacent to each other;
A cam bearing portion that supports the cam element portion so as to rotate and move in the axial direction;
Is provided,
A valve operating apparatus for an engine, wherein the cam element for switching the valve can be switched by moving the cam element part between the first position and the second position on the shaft part,
A positioning mechanism for positioning the cam element portion at the first position and the second position is provided at a fitting portion between the cam element portion and the shaft portion,
The positioning mechanism is
A pressing member held on one of the cam element part or the shaft part;
An engagement portion that is provided on the other of the cam element portion or the shaft portion and in which the pressing member is accommodated by an urging force;
The engaging portion is
Two recesses arranged axially adjacent to each other and to which the pressing member is selectively engaged;
An inner inclined portion provided in each of the two recesses so that the ends are in contact with each other at the boundary between the two recesses ,
In each of the two recesses, the outer inclined portion is provided so as to be positioned on the outer side in the axial direction of the inner inclined portion, and an inclination angle with respect to the axial direction is larger than that of the inner inclined portion .
By moving the cam element portion in the axial direction on the end surface of the cam element portion by engagement with a predetermined operation member, the pressing member reaches the boundary portion from a position engaged with one of the recesses. An end valve cam for moving in the axial direction relative to the engaging portion to a position is provided. A pair of the positioning mechanisms are provided so as to be separated from each other in the axial direction,
3. The valve operating apparatus for an engine according to claim 1 , wherein in the pair of positioning mechanisms, phases of the urging direction of the pressing member as viewed from the axial direction coincide with each other. A second positioning mechanism that is different from the positioning mechanism is provided in the fitting portion between the cam element portion and the shaft portion and is spaced apart from the positioning mechanism in the axial direction.
The second positioning mechanism includes:
A pressing member held on one of the cam element part or the shaft part;
An engagement portion that is provided on the other of the cam element portion or the shaft portion and in which the pressing member is accommodated by an urging force;
The inclined part which has the same inclination | tilt angle as the said outer side inclination part is provided in the both ends of the axial direction in the said engaging part of a said 2nd positioning mechanism, The Claim 1 or Claim 2 characterized by the above-mentioned . Engine valve gear.

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