The present invention relates to a valve operating apparatus for an internal combustion engine.
A conventional valve operating apparatus for an internal combustion engine is disclosed in, for example, Patent Document 1. The aforementioned conventional valve operating apparatus includes a lost motion mechanism that urges a rocker arm in one direction. More specifically, a cylinder head in which the aforementioned valve operating apparatus is mounted includes a boss portion that is formed by casting around a spark plug insertion cylinder (spark plug tube). The aforementioned lost motion mechanism is supported by the boss portion.
The applicants are aware of the following documents, which includes the above described document, as documents related to the present invention.
When forming a boss portion (support portion) for supporting urging means such as a lost motion mechanism by casting on a top face of a cylinder head as in the above described conventional technique, the necessity arises to guide molten metal that has dropped downward one time in an upward direction again. Consequently, when the fluidity of the molten metal is taken into consideration, the boss portion is a shape that has poor manufacturability and a large amount of excess thickness. As a result, the mass of the internal combustion engine increases, and that increase is a factor that causes the fuel consumption performance of the vehicle to deteriorate.
The present invention has been conceived to solve the above described problem, and an object of the present invention is to provide a valve operating apparatus for an internal combustion engine that, with respect to a configuration including urging means that urges a transfer member that transfers an acting force of a cam to a valve, can facilitate manufacture of a support portion of the urging means and suppress an increase in the mass of the internal combustion engine.
A first aspect of the present invention is a valve operating apparatus for an internal combustion engine, comprising:
a transfer member that is interposed between a cam and a valve, and transfers an acting force of the cam to the valve;
urging means that urges the transfer member in one direction; and
a holding member that holds the urging means,
wherein the urging means is attached to a spark plug tube through the holding member.
A second aspect of the present invention is the valve operating apparatus for an internal combustion engine according to the first aspect of the present invention,
wherein the transfer member includes a first rocker arm that rocks in synchrony with rotation of the cam, and
wherein the urging means is means that urges the first rocker arm towards the cam.
A third aspect of the present invention is the valve operating apparatus for an internal combustion engine according to the second aspect of the present invention,
wherein the holding member is attached to the spark plug tube in a condition in which the holding member is rotatable in a circumferential direction of the spark plug tube,
wherein the valve operating apparatus for an internal combustion engine further comprising:
an engagement groove that is formed in one of the urging means and the first rocker aim at a contact portion between the urging means and the first rocker arm; and
a projecting portion that is formed in the other of the urging means and the first rocker arm at the contact portion and that engages with the engagement groove.
A fourth aspect of the present invention is the valve operating apparatus for an internal combustion engine according to the second or third aspect of the present invention,
wherein the transfer member further includes a second rocker arm that is capable of pushing and moving the valve,
wherein the valve operating apparatus for an internal combustion engine further comprises a switching mechanism capable of switching between a connected state in which the first rocker arm and the second rocker arm are in connection and a non-connected state in which the connection is released, and
wherein the urging means is a lost motion mechanism that urges the first rocker arm so as to maintain a state in which the first rocker arm contacts the cam.
A fifth aspect of the present invention is the valve operating apparatus for an internal combustion engine according to the first or second aspect of the present invention,
wherein the urging means is a lash adjuster that has a function of expanding and contracting so as to make a tappet clearance zero and that is disposed so as to support a fulcrum of the transfer member.
A sixth aspect of the present invention is the valve operating apparatus for an internal combustion engine according to any one of the first to fifth aspects of the present invention,
wherein the holding member includes a holding portion that covers a trunk portion of the urging means from outside, and an attachment portion that is attached to the spark plug tube.
A seventh aspect of the present invention is the valve operating apparatus for an internal combustion engine according to the sixth aspect of the present invention,
wherein a cross-sectional shape of the holding portion is an enlarged shape of a cross-sectional shape of the urging means.
An eighth aspect of the present invention is the valve operating apparatus for an internal combustion engine according to any one of the first to seventh aspects of the present invention,
wherein an end portion on an opposite side to an end portion that contacts the transfer member in the urging means is received and stopped by a base member to which the spark plug tube is fixed.
According to the first aspect of the present invention, the necessity to form a support portion of the urging means by casting on a top face of a base member such as a cylinder head on which the valve operating apparatus is mounted is eliminated. As a result, a boss portion (support portion) that includes excess thickness is not required, and hence manufacture of the aforementioned support portion can be facilitated and the mass of the internal combustion engine can be reduced. It is thereby possible to prevent a deterioration in the fuel consumption performance of a vehicle that is caused by an increase in the mass thereof.
According to the second aspect of the present invention, in the case of a configuration that has the transfer member including the first rocker arm that rocks in synchrony with the cam, and that is equipped with the urging means that urges the first rocker aim toward the cam, manufacture of a support portion of the urging means can be facilitated and the mass of the internal combustion engine can be reduced.
According to the third aspect of the present invention, it is possible to accurately perform positioning of the urging means with respect to the first rocker arm without leading to an increase in the number of components.
According to the fourth aspect of the present invention, in the case of the valve operating apparatus in which the urging means is configured as the lost motion mechanism that urges the first rocker arm toward the cam, manufacture of a support portion of the lost motion mechanism can be facilitated and the mass of the internal combustion engine can be reduced.
According to the fifth aspect of the present invention, in the case of the valve operating apparatus in which the urging means is configured as the lash adjuster that supports a fulcrum of the transfer member, manufacture of a support portion of the lash adjuster can be facilitated and the mass of the internal combustion engine can be reduced.
According to the sixth aspect of the present invention, in the case of a configuration equipped with the holding member including the aforementioned holding portion and the aforementioned attachment portion, manufacture of a support portion of the urging means can be facilitated and the mass of the internal combustion engine can be reduced.
According to the seventh aspect of the present invention, since there is no necessity to provide an unrequired protruding portion in the holding member, the weight of the holding member can be reduced.
According to the eighth aspect of the present invention, the holding member carries out only a guiding function that guides the urging means, and the base member is responsible for bearing an urging force of the urging means. As a result, a force that acts on the holding member can be decreased, and hence the weight of the holding member can be reduced.
A valve operating apparatus for an internal combustion engine according to Embodiment 1 of the present invention is configured as a variable valve operating apparatus that is capable of switching an operating state of a valve between a valve operating state and a closed-valve stopped state.
The variable valve operating apparatus 10 of the present embodiment includes a camshaft 12. The camshaft 12 is connected by a timing chain or a timing belt to a crankshaft that is not illustrated in the drawings, and is configured so as to rotate at half the speed of the crankshaft. One main cam 14 and one auxiliary cam 16 are formed per cylinder on the camshaft 12.
Each main cam 14 includes an arcuate base circle portion 14a that is coaxial with the camshaft 12, and a nose portion 14b that is formed such that a part of the base circle is expands outwards in the radial direction. Further, in the present embodiment, each auxiliary cam 16 is constructed as a cam that has only a base circle portion (a zero-lift cam). Each cylinder of the internal combustion engine is provided with one first rocker arm 18 and one second rocker arm 20 that are adjacent to each other. The rocker arms 18 and 20 of each cylinder are rotatably (rockably) supported by one rocker shaft 22.
As shown in
As shown in
The variable valve operating apparatus 10 is equipped with a switching mechanism 32 for switching between a connected state in which the first rocker arm 18 and the second rocker arm 20 are connected together (see
As shown in
The switching mechanism 32 has a pin driving mechanism for driving the switching pin 36 and the like while resisting the urging force of the return spring 42. More specifically, a link arm 46 having an arm portion 46a that contacts against the third switching pin 44 is disposed at a side of the second rocker arm 20. The link arm 46 is rotatably supported by the rocker shaft 22. Further, as shown in
As shown in
The variable valve operating apparatus 10 of the present embodiment is configured so that, as shown in
Furthermore, the variable valve operating apparatus 10 of the present embodiment is configured so that, as shown in
As described in the foregoing, according to the variable valve operating apparatus 10 of the present embodiment, by switching between states in which passage of a current to the electromagnetic solenoid 56 is turned on and off, the operating state of the valves 26 can be switched between a valve operating state and a closed-valve stopped state by utilizing the switching pin 36 and the like. In this connection, the configuration of the pin driving mechanism is not limited to the above described configuration, and for example, the pin driving mechanism may be a mechanism in which the switching pin 36 and the like are driven utilizing an electric motor or hydraulic pressure.
As shown in
As shown in
As shown in
As shown in
The lifter 72 is formed in a cylindrical shape in which one end is open and the other end is closed. The lost motion spring 70 is accommodated inside the lifter 72. More specifically, one end of the lost motion spring 70 contacts a top portion 72a of the lifter 72 that is closed, and the other end thereof contacts the cylinder head 62. That is, the lost motion spring 70 is configured so as to urge the first rocker arm 18 toward the main cam 14 through the top portion 72a of the lifter 72 while utilizing the cylinder head 62 as a bearing surface that receives the spring load.
In other words, the holding portion 68b is formed so as to cover the lateral face of the lifter 72 that is a trunk portion of the lost motion mechanism 60 and a lateral face of the lost motion spring 70 from outside. Further, a cross-sectional shape (annular circular shape) of the holding portion 68b that is taken in a direction perpendicular to the axis line of the lost motion mechanism 60 is an enlarged shape of the cross-sectional shape (circular shape) of the lifter 72.
As shown in
Further, as shown in
As described above, the lost motion mechanism 60 of the present embodiment is attached to the spark plug tube 66 through the holding member 68. Therefore, it is not necessary to form a support portion of the lost motion mechanism 60 by casting on the top face of the cylinder head 62. As a result, as shown in
Further, in the above described variable valve operating apparatus 10, the first rocker arm 18 is disposed at a position that is surrounded by the second rocker arm 20 that pushes and moves the two valves 26. In other words, in each cylinder, the first rocker arm 18 is disposed so as to be sandwiched between two of the valves 26. Further, the spark plug tube 66 is disposed in the center of each cylinder. In addition, although not shown in the drawings in this case, in general, the two valves 26 are disposed at positions that are equidistant from the center of the respective cylinders in which the spark plug tube 66 is arranged and that are symmetrical positions in the longitudinal direction of the cylinder head 62 when taking the center of each cylinder as a reference. Accordingly, the first rocker arm 18 and the spark plug tube 66 are disposed adjacent to each other as shown in
As described above, one end of the lost motion spring 70 contacts the top portion 72a of the lifter 72 that is closed, and the other end thereof contacts the cylinder head 62. According to this configuration, the holding portion 68b of the holding member 68 carries out only a guiding function that guides expansion and contraction of the lost motion mechanism 60, and the cylinder head 62 as a base member is responsible for bearing the spring load of the lost motion spring 70. Since it is thereby possible to decrease a force that acts on the holding member 68, the weight of the holding member 68 can be reduced.
Further, as described above, the cross-sectional shape of the holding portion 68b that is taken in a direction perpendicular to the axis line of the lost motion mechanism 60 is an enlarged shape of the cross-sectional shape of the lifter 72. Since it is thus not necessary to provide an unrequired protruding portion in the holding member 68, the weight of the holding member 68 can be reduced.
As described above, the attachment portion 68a of the holding member 68 is supported by the spark plug tube 66 in a state in which the holding member 68 is rotatable in the circumferential direction of the spark plug tube 66. As shown in
If a configuration is employed in which, unlike the above described configuration, the rotational position of an attachment portion with respect to a spark plug tube is fixed in a case where the lost motion mechanism 60 is held by means of the holding member 68 that is separate from the cylinder head 62, the following issue arises. That is, if a contact point between the first rocker arm and the lost motion mechanism deviates from the center of the lost motion mechanism, a force that pushes the lost motion spring in the radial direction thereof acts on the holding member. Accordingly, it is important that positioning of the lost motion mechanism with respect to the first rocker arm is performed accurately. Consequently, when adopting a configuration that fixes the rotational position of the attachment portion with respect to the spark plug tube, the necessity arises to accurately perform assembly with regard to positioning of the lost motion mechanism with respect to the first rocker aim. Therefore, a high degree of processing and assembling accuracy is required with respect to the spark plug tube that is press-fitted into the cylinder head, and the number of working man-hours required for the aforementioned process increases.
In contrast, according to the configuration of the present embodiment, by causing the engagement groove 72b formed in the lifter 72 and the pad 18a formed in the first rocker arm 18 to engage while configuring the attachment portion 68a of the holding member 68 so as to be rotatable with respect to the spark plug tube 66, it is possible to accurately perform positioning of the lost motion mechanism 60 with respect to the first rocker arm 18 without leading to an increase in the number of components.
Note that, in the above described Embodiment 1, the main cam 14 corresponds to “cam” according to the above described first aspect of the present invention, the first rocker arm 18 corresponds to “transfer member” according to the first aspect of the present invention, and the lost motion mechanism 60 corresponds to “urging means” according to the first aspect of the present invention.
In addition, the pad 18a formed on the first rocker arm 18 corresponds to “projecting portion” according to the above described third aspect of the present invention.
Further, the cylinder head 62 corresponds to “base member” according to the above described eighth aspect of the present invention.
Next, Embodiment 2 of the present invention is described referring to
The valve operating apparatus 80 shown in
As shown in
One end of the lash adjuster 88 contacts the aforementioned other end of the rocker arm 84 as described above. The other end of the lash adjuster 88 contacts the cylinder head 62. More specifically, the lash adjuster 88 is configured so that the rocker arm 84 can be urged towards the cam 82 while utilizing the cylinder head 62 as a bearing surface that receives a load that acts on the lash adjuster 88 through the rocker arm 84.
In other words, in the present embodiment also, the holding portion 90b is formed so as to cover the lateral face of the lash adjuster 88 that is a trunk portion of the lash adjuster 88 from outside. Further, a cross-sectional shape (annular circular shape) of the holding portion 90b that is taken in a direction perpendicular to the axis line of the lash adjuster 88 is an enlarged shape of the cross-sectional shape (circular shape) of the lash adjuster 88.
In addition, according to the present embodiment, a projecting portion 88a of the lash adjuster 88 that functions as a fulcrum of the rocker arm 84 is configured so as to engage with an engagement groove 84a provided in the aforementioned other end of the rocker arm 84.
As described above, according to the present embodiment, the lash adjuster 88 that is used as urging means that urges the rocker arm 84 that is a transfer member is attached to the spark plug tube 66 through the holding member 90. Thus, the necessity to form a support portion of the lash adjuster 88 by casting on the top face of the cylinder head 62 is eliminated. As a result, a boss portion that includes excess thickness is not required, and thus manufacture of the aforementioned support portion can be facilitated and the mass of the internal combustion engine can be reduced. It is thereby possible to prevent a deterioration in the fuel consumption performance of the vehicle that is attributable to an increase in the mass of the internal combustion engine. In addition, the same advantageous effects as in the above described Embodiment 1 can also be achieved.
Note that, in the above described Embodiment 2, the rocker arm 84 corresponds to “transfer member” according to the above described first aspect of the present invention, and the lash adjuster 88 corresponds to “urging means” according to the first aspect of the present invention.
In the above Embodiment 1, an example was described of a configuration in which the lost motion mechanism 60 that urges the first rocker arm 18 is attached to the spark plug tube 66 through the holding member 68. However, the configuration of a valve operating apparatus for an internal combustion engine to which the present invention can be applied is not limited to the above described configuration. For example, a configuration as shown in
A variable valve operating apparatus 100 shown in
The variable valve operating apparatus 100 is also equipped with a lost motion mechanism 108 that urges the first rocker arm 102 toward the main cam 14 through the lost motion arm 106. The lost motion mechanism 108 includes a lost motion spring 110 and a lifter 112 that is interposed between the lost motion spring 110 and the lost motion arm 106.
In the configuration shown in
Further, as shown in
Although examples in which the auxiliary cam 16 is configured as a zero-lift cam have been described in the foregoing Embodiments 1 and 2, an auxiliary cam of the present invention is not limited to a zero-lift cam. More specifically, for example, with respect to the configuration of the above described variable valve operating apparatus 10, a configuration may also be adopted in which the auxiliary cam includes a nose portion that is constructed so as to obtain a lift that is less than that of the main cam 14. According to a configuration in which this kind of auxiliary cam is provided, it is possible to switch a lift amount (and/or a working angle) of a valve between two stages by means of the main cam and auxiliary cam.
Further, in the above described Embodiment 1, the variable valve operating apparatus 10 is described as an example of a valve operating apparatus. However, as described above in Embodiment 2 also, a valve operating apparatus that is an object of the present invention is not limited to a valve operating apparatus configured as a variable valve operating apparatus. More specifically, it is sufficient that the valve operating apparatus is equipped with a holding member that holds urging means that urges a transfer member that is interposed between a cam and a valve.
Furthermore, in the foregoing Embodiments 1 and 2, the first rocker arm 18 or the like is described as an example of an object that is urged by the lost motion mechanism 60 or the lash adjuster 88 functioning as urging means. However, a transfer member according to the present invention is not limited to a rocker arm. More specifically, it is sufficient that a transfer member is a member that is interposed between a cam and a valve and transfers an acting force of the cam to the valve.
Further, in the above Embodiment 1, an example is described in which the engagement groove 72b is formed in the top portion 72a of the lifter 72 of the lost motion mechanism 60, and the pad (projecting portion) 18a that engages with the engagement groove 72b is formed at a region that faces the lifter 72 on the first rocker arm 18. However, the present invention is not limited thereto and, for example, a configuration may be adopted in which a projecting portion such as a pad is formed on the top portion 72a side of the lifter 72 that is the urging means and an engagement groove is formed on first rocker arm 18 side that is the transfer member.
In addition, the above Embodiment 1 has been described taking the lost motion mechanism 60 that urges the first rocker arm 18 in a pushing direction towards the main cam 14 as an example. However, the configuration of urging means according to the present invention is not limited thereto and, for example, it is sufficient that the urging means is means that generates an urging force in a direction that draws in a transfer member such as the first rocker arm 18.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2010/056332 | 4/7/2010 | WO | 00 | 9/21/2012 |