JP2018105176A - Variable valve mechanism for engine - Google Patents

Abstract

In a cam switching mechanism (variable valve mechanism) mounted on an engine 1, lubricating oil can be supplied to a guide groove 46 provided on the outer periphery of the cam unit at a low cost. A cam shaft is inserted into a camshaft by spline coupling with a camshaft, and a shift pin is engaged with a spiral guide groove provided on the outer periphery of the camshaft. By sliding in the direction, it is possible to select either of the plurality of cams 41 and 42. The sleeve 43 is provided with a through hole 43 c that penetrates from the inner periphery to the guide groove 46 and opens at the bottom of the guide groove 46, and supplies lubricating oil (for example, engine oil) at the spline coupling portion to the guide groove 46. . [Selection] Figure 9

Description

  The present invention relates to a variable valve mechanism used in a valve system of an engine, and in particular, a cam switching system in which a cam unit externally attached to a camshaft is slid in an axial direction (hereinafter also referred to as a camshaft direction). Related to things.

  Conventionally, as a variable valve mechanism that can change the lift characteristics of an intake valve of an engine, for example, as described in Patent Document 1, a cam carrier (hereinafter referred to as a cam unit) provided with a plurality of cams is camped. A cam switching type is known in which a cam is switched to one of the cams by extrapolating the shaft and sliding it in the axial direction. In this example, the intake valve for each cylinder of the engine is driven by one of the cams via a rocker arm.

  The cam unit is extrapolated to the camshaft on the intake side, and spline inner teeth provided on the inner periphery thereof are meshed with spline outer teeth provided on the outer periphery of the camshaft. On the other hand, a spiral guide groove is provided on the outer periphery of the cam unit. By engaging a shift pin with the guide groove from the outside, the cam carrier rotates with the rotation of the camshaft and slides in the camshaft direction. To come.

JP-T-2006-520869

  When the guide groove is provided on the outer periphery of the cam unit and the shift pin is engaged with the guide groove as in the conventional example, lubrication of the guide groove and the shift pin becomes a problem. This is because when the shift pin is inserted into the guide groove of the cam unit that rotates at a high speed integrally with the cam shaft, or when the shift pin is pulled out from the outside, there is a concern about wear of the guide groove or the shift pin.

  Conventionally, a structure in which engine oil (lubricating oil) is sprayed onto a camshaft of an engine with a shower pipe is known (see, for example, Japanese Patent Application Laid-Open No. 2010-164209). Correspondingly, adding a nozzle of a shower pipe so as to spray engine oil toward the guide groove tends to increase the cost.

  In view of such a point, an object of the present invention is to enable low-cost supply of lubricating oil to a guide groove provided on the outer periphery of a cam unit in the variable valve mechanism of the cam switching type as described above. .

  In order to achieve the above object, according to the present invention, first, a cylindrical cam unit is extrapolated to a camshaft of an engine, and a shift pin is engaged from the outside with a spiral guide groove provided on the outer periphery of the cam unit. It is intended for a variable valve mechanism of an engine that allows one of a plurality of cams provided in the cam unit to be selected by sliding in the cam shaft direction as the shaft rotates.

  When the spline inner teeth provided on the inner periphery of the sleeve of the cam unit and the spline outer teeth provided on the outer periphery of the camshaft are meshed with each other, the sleeve is guided from the inner periphery to the guide. A through hole that penetrates to the groove and opens at the bottom of the guide groove is provided.

  In the variable valve mechanism of the engine configured as described above, any one of a plurality of cams can be selected by sliding a cam unit externally attached to the cam shaft in the axial direction. When the cam unit is slid in this way, a shift pin is inserted from the outside into the guide groove of the cam unit that rotates at high speed integrally with the camshaft, or pulled out in the opposite direction.

  In this regard, the present inventors pay attention to the fact that when the inner spline teeth on the inner periphery of the sleeve and the outer spline teeth on the outer periphery of the camshaft are meshed with each other, lubricating oil is supplied thereto. The lubricating oil is used for lubricating the guide groove and the shift pin. Therefore, a through hole is provided in the sleeve so as to penetrate from the inner periphery to the guide groove, and the guide groove and the shift pin are lubricated by the lubricating oil supplied to the bottom of the guide groove through the through hole. Will be.

  Note that the lubricating oil supplied to the spline coupling portion as described above may be supplied to the outer peripheral surface via an oil passage provided inside the camshaft, but ensures the strength of the camshaft. In order to do this, it is desirable to supply from the outside. Therefore, for example, engine oil supplied to the journal portion of the camshaft may be used and supplied to the spline coupling portion via the outer peripheral surface of the camshaft.

  The present invention provides a cam unit sleeve when a spiral guide groove is provided on the outer periphery of a cam unit externally attached to a camshaft, and a shift pin is engaged with the guide groove from the outside to slide the cam unit. By providing a through hole so that it penetrates from the inner circumference to the bottom of the guide groove, a part of the lubricating oil for lubricating the spline on the inner circumference of the sleeve is supplied, and the lubrication of the guide groove and the shift pin is inexpensive. You can do it.

It is a schematic block diagram of the valve operating system of the engine equipped with the variable valve operating mechanism which concerns on embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the cam unit extrapolated by the intake camshaft. It is a perspective view which shows the structure of the valve system by the side of intake in a 1st cylinder. It is a longitudinal cross-sectional view of two integrated cam units. FIG. 5 is a cross-sectional view of the cam unit and the like taken along line VV in FIG. 4. It is a fragmentary sectional view for demonstrating the structure of the cam unit of a 1st cylinder. It is a figure for demonstrating the structure of the cam switching mechanism which slides a cam unit by engagement with a shift pin and a guide groove. It is a figure explaining operation | movement of the cam switching mechanism. FIG. 5 is a view corresponding to FIG. 4 for explaining the flow of engine oil from the spline coupling portion to the lock mechanism and the guide groove.

  Hereinafter, an embodiment in which the present invention is applied to an engine valve train will be described. The engine 1 of this embodiment is an in-line four-cylinder gasoline engine 1 as an example, and as shown schematically in FIG. 1, the first to fourth four cylinders 3 (# 1 to # 4) are provided. They are arranged in the longitudinal direction of a cylinder block (not shown), that is, in the front-rear direction of the engine 1 (left-right direction in FIG. 1 indicated by arrows). Hereinafter, the front-rear direction of the engine 1 may be simply referred to as front-rear.

  As seen from above in FIG. 1, a cam housing 2 is disposed in the upper part (cylinder head) of the engine 1 and accommodates intake and exhaust valve systems. That is, as shown by broken lines in FIG. 1, two intake valves 10 and two exhaust valves 11 are provided in each of the four cylinders 3 arranged in a line in the longitudinal direction of the engine 1, They are driven by the intake camshaft 12 and the exhaust camshaft 13. A VVT (Variable Valve Timing) 14 is attached to the front ends of the intake camshaft 12 and the exhaust camshaft 13, respectively.

  For example, as shown in FIG. 2 for the intake camshaft 12, the cam housing 2 is provided with five cam holders 21 to 25 corresponding to the front and rear ends of the intake camshaft 12 and between the cylinders. Five journal portions of the camshaft 12 are rotatably supported. That is, the first cam holder 21 at the foremost portion (left end portion in FIG. 2) supports the first journal portion provided on the front piece of the intake camshaft 12.

  On the other hand, the four journal portions 2 to 5 except the first journal portion are provided not on the intake camshaft 12 itself but on the sleeve 43 externally attached thereto, which will be described later in detail. Are supported by # 5 cam holders 22-25. And the oil supply groove | channels 21a-25a extended in the circumferential direction are provided in the inner periphery of each of these cam holders 21-25, and engine oil (lubricating oil) is supplied through the oil path which is not shown in figure. .

  As a characteristic part of the present invention, the intake camshaft 12 is provided with a cam switching mechanism (variable valve mechanism of the present invention) that switches the cams 41 and 42 that drive the intake valve 10 and changes its lift characteristics. . As an example, as shown in FIG. 3 with respect to the first cylinder 3 (# 1), two intake valves arranged in the direction of the axis X of the intake camshaft 12 (cam shaft direction, engine longitudinal direction) for each cylinder 3. Corresponding to 10 respectively, two cams 41 and 42 having different profiles are provided.

  In FIG. 3, a low lift cam 41 and a high lift cam 42 are arranged from the left side (one side in the axis X direction) to the right side (the other side), and either one is selected and the intake valve is connected via the rocker arm 15. 10 is driven. The base circles of the low lift cam 41 and the high lift cam 42 have the same diameter and are formed as arc surfaces that are continuous with each other. In FIG. 3, the low lift cam 40 is switched to the roller circle 15a of the rocker arm 15 in the base circle section. A state of contact is shown.

  In this manner, when the roller 15a of the rocker arm 15 is in contact with the base circle section, the intake valve 10 is not lifted. That is, the intake valve 10 is a general poppet valve, and a retainer is attached to the upper portion of the stem portion 10 a and receives an upward pressing force from the valve spring 16. Thereby, as shown by the solid line in FIG. 3, the umbrella portion of the intake valve 10 closes the intake port (shown by the phantom line).

  When the intake camshaft 12 rotates in the direction of arrow R from this state, the low lift cam 41 presses the roller 15a and pushes the rocker arm 15 (not shown). As a result, the rocker arm 15 drives the intake valve 10 according to the profile of the low lift cam 41, and the intake valve 10 is lifted against the reaction force of the valve spring 16 as indicated by the phantom line in FIG.

-Cam switching mechanism-
In the present embodiment, the cam that lifts the intake valve 10 via the rocker arm 15 as described above is switched to either the low lift cam 41 or the high lift cam 42. That is, as shown in FIGS. 4 to 6 in addition to FIGS. 2 and 3, in this embodiment, two cams 41 and 42 are integrally provided at a predetermined position of the cylindrical sleeve 43 to form a cam unit. 4 is slidably fitted on the intake camshaft 12.

  Specifically, as shown in FIGS. 1 and 2, in the present embodiment, the long sleeve 43 extends over the first cylinder 3 (# 1) and the second cylinder 3 (# 2), Two cams 41, 42 are provided at portions corresponding to the two intake valves 10 of each cylinder 3, that is, at a total of four locations. That is, the two cam units 4 of the first cylinder 3 (# 1) and the second cylinder 3 (# 2) are connected and configured integrally. The same applies to the cam units 4 of the third cylinder 3 (# 3) and the fourth cylinder 3 (# 4).

  In FIG. 4, the two cam units 4 of the first cylinder 3 (# 1) and the second cylinder 3 (# 2) have a spline on the inner periphery of the sleeve 43, as shown in a vertical section including the axis X. Teeth 44 are formed, which mesh with spline external teeth 12 a formed on the outer periphery of the intake camshaft 12. That is, as shown in FIG. 5 in the cross section taken along the line VV in FIG. 4, the cam unit 4 (sleeve 43) is splined to the intake camshaft 12 and rotates integrally and slides in the direction of the axis X. It is like that.

  As shown in FIG. 4, in the present embodiment, the spline inner teeth 44 are formed on the inner periphery of the sleeve 43 corresponding to the first cylinder 3 (# 1), and the rear end portion thereof is shown in FIG. 2 corresponds to the second journal portion supported by the second cam holder 23 as described above. On the other hand, spline internal teeth are not formed in the portion corresponding to the second cylinder 3 (# 2) for weight reduction. A third journal portion supported by the third cam holder 23 is provided at the rear end portion of the sleeve 43, but no spline internal teeth are formed on the inner periphery thereof.

  On the outer periphery of the sleeve 43, guide grooves 46 and 47 with which the shift pin 51 is engaged are provided in order to slide the cam unit 4 as described below. That is, as shown in FIGS. 2 and 3 and the like, a clockwise spiral guide extending in the circumferential direction over the entire circumference at the intermediate portion in the axis X direction of the cam unit 4 of the first cylinder (# 1). A groove 46 is provided. Similarly, the cam unit 4 of the second cylinder (# 2) is provided with a counterclockwise spiral guide groove 47.

  An actuator 5 is provided for each cylinder 3 above the intake camshaft 12 so that the shift pins 51 can be engaged with the guide grooves 46 and 47, respectively, and extends in the direction of the axis X, for example. The cam housing 2 supports the stay 52 (see FIGS. 1 and 2). The actuator 5 drives the shift pin 51 forward and backward by an electromagnetic solenoid. When the shift pin 51 advances in the ON state, the actuator 5 comes into engagement with one of the guide grooves 46 and 47.

−Cam switching operation−
As the shift pin 51 thus advanced engages with the guide groove 46 of the first cylinder 3 (# 1), for example, the rotation of the intake camshaft 12 will be described with reference to FIGS. Accordingly, the shift pin 51 relatively moves on the outer peripheral surface of the cam unit 4 in the circumferential direction, and also moves along the guide groove 46 in the axis X direction (that is, obliquely). At this time, the cam unit 4 actually slides in the direction of the axis X while rotating.

  Specifically, first, as shown in FIG. 7, the guide groove 46 is located near the one side (left side in FIG. 7) and the other side (right side in FIG. 7) on the outer periphery of the cam unit 4. It has straight groove portions 46a and 46b that extend linearly in the circumferential direction, and an S-shaped curved groove portion 46c that connects these straight groove portions 46a and 46b. As shown in FIG. 3, at the position where the low lift cam 41 is selected (low lift position), the straight groove portion 46 a on one side in the axis X direction faces the shift pin 51 of the actuator 5.

  When the actuator 5 operates to advance the shift pin 51 in this state, the shift pin 51 engages with the straight groove portion 46a on one side of the guide groove 46 as shown in the upper part of FIG. Move relative to the bottom of the figure. Then, as shown in the middle part of FIG. 8, the curved groove 46c is reached, and the shift pin 51 moves relative to the lower side of the drawing along the curved groove 46c, and also moves to the other side in the axis X direction, that is, obliquely. It becomes like this.

  As a result, the shift pin 51 actually presses and slides the cam unit 4 to one side in the direction of the axis X, and switches to a position where the high lift cam 42 is selected (high lift position). At this time, as shown in the lower stage of FIG. 8, the shift pin 51 reaches the straight groove portion 46 b on the other side of the guide groove 46, and then leaves the guide groove 46. The slide amount S of the cam unit 4 when switching from the low lift position to the high lift position in this way is the same as the interval between the low lift cam 41 and the high lift cam 42, as shown in FIG.

  When the cam unit 4 is switched to the high lift position as described above, although not shown, the straight groove portion on the other side in the axis X direction of the guide groove 47 provided in the cam unit 4 of the second cylinder (# 2). Is opposed to the shift pin 51 of the actuator 5. Then, by turning on the actuator 5 and engaging the shift pin 51 with the guide groove 47, the cam unit 4 is slid to the other side in the axis X direction in accordance with the rotation of the intake camshaft 12 in the same manner as described above. And can be moved to a low lift position.

-Lock mechanism-
In the present embodiment, the lock mechanism 6 (positioning mechanism) for holding the position of the cam unit 4 (low lift position, high lift position) when the cams 41 and 42 are switched as described above is the first cylinder. 3 (# 1) cam unit 4 and intake camshaft 12 are provided. That is, as shown in FIGS. 2 and 6, two annular grooves 48 and 49 are formed on the inner peripheral surface of the sleeve 43 corresponding to the cam unit 4 of the first cylinder 3 (# 1). Are formed side by side in the direction of the axis X (the left-right direction in FIG. 6), and an annular protrusion 50 is formed so as to remain therebetween.

  Then, when the cam unit 4 is in the low lift position or the high lift position, the intake camshaft 12 is fitted with two lock balls so as to be able to protrude and retract on the outer periphery thereof so as to be fitted into the annular grooves 48 and 49, respectively. 61 is disposed. That is, in the present embodiment, through-holes 12b having circular cross-sections that pass through the intake camshaft 12 and open at two locations on the outer peripheral surface thereof are formed, and two lock balls 61, coil springs 62, and Is housed.

  In other words, the lock balls 61 are disposed at two positions 180 degrees apart in the circumferential direction on the outer periphery of the intake camshaft 12, and each is disposed at both ends of the coil spring 62, and the through force is caused by the spring force. It is urged | biased so that it may push outward from the opening of the both ends of 12b. When the cam unit 4 is in the low lift position (the position on the right side in FIG. 6) as shown in the upper part of FIG. 6, the two lock balls 61 are fitted into the annular grooves 48 to slide the cam unit 4. Regulate and hold in a low lift position.

  On the other hand, as shown in the lower part of FIG. 6, when the cam unit 4 is in the high lift position (the left position in FIG. 6), the two lock balls 61 are fitted into the annular grooves 49, and the cam unit 4 slides. And is held at a high lift position. Then, as described above with reference to FIG. 8, when the cam unit 4 slides from the low lift position to the high lift position, for example, the lock ball 61 moves over the annular protrusion 50 and moves from the annular groove 48 to the annular groove 49. To do.

  At this time, as the cam unit 4 slides, the lock ball 61 is first pushed by the annular protrusion 50, moves against the spring force of the coil spring 62, and comes out of the annular groove 48. Then, after getting over the annular protrusion 50, the lock ball 61 is fitted into the annular groove 49 by the spring force of the coil spring 62. In addition, when the cam unit 4 slides from the high lift position to the low lift position, the lock ball 61 is detached from the annular groove 49 so as to get over the annular protrusion 50 and then fit into the annular groove 48. .

−Lubrication of guide groove−
By the way, when the guide grooves 46 and 47 are provided on the outer periphery of the cam unit 4 and the shift pin 51 is engaged with the guide grooves 46 and 47 as in the cam switching mechanism described above, how to lubricate them becomes a problem. . This is considered that when the shift pin 51 is inserted from the outside into the guide grooves 46 and 47 of the cam unit 4 that rotates at a high speed integrally with the intake camshaft 12, they are worn out. Because.

  In this regard, it is known that engine oil (lubricating oil) is sprayed onto the journal portion of the camshaft by a shower pipe as a general lubrication method for the valve system of the engine. Correspondingly, providing the nozzle of the shower pipe so as to spray the engine oil in the guide grooves 46 and 47 has a difficulty in incurring high costs.

  In this embodiment, engine oil supplied to the journal portion of the intake camshaft 12 (in this embodiment, the journal portion of the sleeve 43) is guided to the inner periphery of the sleeve 43 through the through holes 43a and 43b. The joint is lubricated. A through hole 43 c is provided in the sleeve 43 so as to guide the engine oil from the annular grooves 48 and 49 of the lock mechanism 6 to the guide groove 46. The guide groove 46 and the shift pin 51 are lubricated by the engine oil thus guided.

  That is, first, as described above, the cam holders 21 to 25 are provided with the oil supply grooves 21a to 25a, respectively, so that the engine oil is supplied from this to the journal portion of the sleeve 43 of the intake camshaft 12. Engine oil is supplied. As shown in FIG. 4, in the sleeve 43 corresponding to the first and second cylinders 3 (# 1, # 2), through-holes 43a, 43b are provided in the second journal portion between both cylinders. ing.

  These through holes 43a and 43b communicate with the oil supply groove 22a of the second cam holder 22, respectively, and supply engine oil to the inner peripheral surface of the sleeve 43. The engine oil supplied in this way is contained in the spline. This is used for lubricating the teeth 44 and the spline external teeth 12a. Although not shown in FIG. 4, the sleeve 43 corresponding to the third and fourth cylinders 3 (# 3, # 4) is provided with through holes 43a, 43b in the fourth journal portion.

  As shown in FIG. 9 in addition to FIG. 4, in the present embodiment, the two through holes 43 a and 43 b are provided at two locations that are separated by 180 ° in the circumferential direction of the sleeve 43. Then, the sleeve 43 is externally fitted to the intake camshaft 12 so that the respective through holes 43a and 43b are aligned with the lock ball 61 in the circumferential direction. In other words, through holes 43a and 43b are provided at two locations corresponding to the two lock balls 61, respectively.

  Accordingly, as indicated by arrows O1 and O2 in FIG. 9, the engine oil supplied to the inner peripheral surface of the sleeve 43 from the two through holes 43a and 43b is axially supplied by the spline inner teeth 44 and the spline outer teeth 12a. Guided in the X direction and supplied to the two lock balls 61. The engine oil thus supplied to the two lock balls 61 is also supplied to the annular grooves 48 and 49 and the annular protrusion 50 therebetween.

  In the present embodiment, an opening is formed in the annular protrusion 50 between the annular grooves 48 and 49, while extending outward (upward in FIG. 9) from the opening and penetrating the sleeve 43, the guide groove 46. A through hole 43c is provided at the bottom of the opening. Therefore, the engine oil supplied to the annular grooves 48 and 49 and the annular protrusion 50 as described above flows through the through hole 43c as shown by an arrow O3 in FIG. 9 and is supplied to the bottom of the guide groove 46. Will be.

  That is, the engine oil supplied to the journal portion of the intake camshaft 12 is guided to the inner periphery of the sleeve 43 through the through holes 43a and 43b, lubricates the spline coupling portion, and a part of the engine oil is guided by the through hole 43c. It is also supplied to the groove 46 to be used for lubrication of the guide groove 46 and the shift pin 51. Engine oil is supplied to the guide groove 47 from a nozzle of a shower pipe (not shown).

  As described above, in the engine 1 according to the present embodiment, when the cam switching mechanism for switching the two cams 41 and 42 is provided by sliding the cam unit 4 attached to the intake camshaft 12, the first and The cam unit 4 of the second cylinder 3 and the cam units 4 of the third and fourth cylinders 3 are each integrated by a sleeve 43. As a result, the two cam units 4 operate as one body, and the cost can be reduced by reducing the number of shift pins 51 and actuators 5 for operating them.

  Thus, in order to switch between the two cams 41 and 42, spiral guide grooves 46 and 47 are provided on the outer periphery of the sleeve 43, and the shift pin 51 is engaged therewith, whereby the cam unit 4 (sleeve 43). At this time, the shift pin 51 is inserted into or extracted from the guide grooves 46 and 47 of the sleeve 43 that rotates at a high speed.

  Therefore, a part of the engine oil supplied to the spline joint between the sleeve 43 and the intake camshaft 12 is also used for lubrication of the lock mechanism 6 and further supplied to the guide groove 46 through the through hole 43c. Since the guide groove 46 and the shift pin 51 are used for lubrication, there is no need to provide a nozzle of the shower pipe corresponding to the guide groove 46, and the lubrication can be performed correspondingly.

-Other embodiments-
The configuration of the present invention is not limited to the above-described embodiment. This embodiment is merely an example, and the configuration of the present invention is of course not limited to applications. For example, in the above-described embodiment, the cam unit 4 is provided with the low lift cam 41 and the high lift cam 42 for each intake valve 10 so that the lift characteristics are switched between two levels of high and low. However, the present invention is not limited to this. You may comprise so that a characteristic may be switched in three steps.

  In the above-described embodiment, part of the engine oil that lubricates the spline coupling portion between the sleeve 43 and the intake camshaft 12 is supplied to the lock ball 61 and then supplied to the guide groove 46 through the through hole 43c. However, the present invention is not limited to this, and a part of the engine oil that lubricates the spline coupling portion may be directly supplied to the guide groove 46.

  In the above embodiment, the through holes 43a and 43b are provided at two locations on the sleeve 43 so that the journal portion supplies the inner periphery of the sleeve 43 to lubricate the spline connecting portion. For example, the spline coupling portion may be lubricated by an oil passage provided inside the intake camshaft 12.

  In the embodiment, engine oil is supplied to only the guide groove 46 of the two guide grooves 46, 47 of the sleeve 43 through the through hole 43c. The guide groove 47 is separately provided with a shower. It is necessary to supply engine oil by a pipe nozzle or the like. However, the present invention is not limited to this, and the engine oil is supplied to the guide groove 47 from the through hole provided in the sleeve 43 as well as the guide groove 46. It may be.

  Furthermore, in the above-described embodiment, the example in which the cam switching mechanism is provided on the intake side in the valve train of the engine 1 has been described, but this may be on the exhaust side or on both sides. In the in-line four-cylinder engine 1 as in the above-described embodiment, the cam units 4 of the first and second cylinders 3 (# 1, # 2) are connected and integrated, and the third and fourth cylinders 3 (# 3, # 2, The cam unit 4 of # 4) is not limited to being connected and integrated.

  For example, the present invention can be applied to the case where the cam units 4 of the first and second cylinders 3 (# 1, # 2) are connected and integrated in an in-line three-cylinder engine, regardless of the number of cylinders. The present invention can also be applied to the case where the cam units 4 of the cylinders 3 are individually operated. Further, the engine 1 may have five or more in-line cylinders, and the present invention can also be applied to engines having various cylinder arrangements such as a V type instead of in-line.

  According to the present invention, in a cam switching type variable valve mechanism provided in a valve system of an engine, when a spiral guide groove is provided in a cam unit extrapolated to a camshaft, the guide groove is lubricated at low cost. Since it can be realized, it is highly effective when applied to an engine mounted on an automobile, for example.

DESCRIPTION OF SYMBOLS 1 Engine 4 Cam unit 41 Low lift cam 42 High lift cam 43 Sleeve 43c Through-hole 44 Spline internal tooth 46 Guide groove 5 Actuator 51 Shift pin 12 Intake cam shaft 12a Spline external tooth X Intake cam shaft axis (cam shaft direction, engine longitudinal direction)

Claims (1)

By extrapolating a cylindrical cam unit to the camshaft of the engine, engaging a shift pin from the outside with a spiral guide groove provided on the outer periphery, and sliding it in the camshaft direction as the camshaft rotates, In the variable valve mechanism of the engine that can select any one of a plurality of cams provided in the cam unit,
The spline inner teeth provided on the inner periphery of the sleeve of the cam unit and the spline outer teeth provided on the outer periphery of the camshaft are meshed,
The variable valve mechanism for an engine according to claim 1, wherein the sleeve is provided with a through hole that penetrates from the inner periphery to the guide groove and opens at the bottom of the guide groove.

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