Internal combustion engine, method for determining phase of rotation direction of shaft member

Abstract

To position an axial member at a reference phase when a power supply to an internal combustion engine is suddenly interrupted due to a power outage or other incidents.SOLUTION: An engine 100 comprises: an actuator 7; a rotating shaft 6 that is rotationally driven by the actuator 7; and a positioning mechanism 20 that positions the rotating shaft 6 at a reference phase, which serves as a reference for displacement in a rotational direction, by engaging with the rotating shaft 6 in the rotational direction thereof.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine and a method for determining the phase of a shaft member in the rotational direction. [Background technology]

[0002] 2. Description of the Related Art A variable valve timing mechanism is known as an engine valve train, which is capable of changing the valve timing of intake valves and exhaust valves depending on the operating state of the engine.

[0003] For example, in the valve train disclosed in Patent Document 1, an actuator rotates an eccentric rocker shaft to change the fulcrum position of the rocker arm, thereby enabling the use of low-, medium-, and high-speed cams with different cam profiles to change the valve timing of the valve train. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-288212 Summary of the Invention [Problem to be solved by the invention]

[0005] In such an internal combustion engine, the device recognizes the current rotational phase of the shaft member, and then drives the drive source to rotate the shaft member to the appropriate phase and change the desired valve timing. However, if the power supply to the device is suddenly stopped due to a power outage or other reason, the device loses track of the current rotational phase of the shaft member. In this case, by aligning the shaft member with a reference phase that serves as a reference for the rotational direction and having the device recognize that the shaft member has been positioned at the reference phase, it is possible to realign the actual phase of the shaft member with the phase recognized by the device. However, in conventional internal combustion engines, it was not possible to position the shaft member at the reference phase in such a situation.

[0006] In view of the above circumstances, an object of the present invention is to position the shaft member at the reference phase when the power supply to the internal combustion engine is suddenly stopped due to a power outage or the like. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention is characterized by an internal combustion engine comprising a drive source, a shaft member that is rotationally driven by the drive source, and a positioning mechanism that engages with the shaft member in its rotational direction, thereby positioning the shaft member at a reference phase that serves as a basis for displacement in the rotational direction.

[0008] According to the present invention, by mechanically engaging the shaft member with the positioning mechanism, the shaft member can be accurately positioned to the reference phase. Therefore, for example, even when power is not supplied, the shaft member can be manually positioned to the reference phase. Furthermore, after power is restored, the shaft member can be rotated by a drive source and positioned at the reference phase. After positioning the shaft member to the reference phase, the device can recognize that the shaft member is positioned at the reference phase, thereby aligning the actual phase of the shaft member with the phase recognized by the device.

[0009] In the above internal combustion engine, the shaft member has a recess recessed in a radial direction thereof and an engagement surface forming the recess, and the positioning mechanism has a positioning part having a first reference surface that engages with the engagement surface in the rotational direction of the shaft member and positions the shaft member at the reference phase. The shaft member can be positioned at the reference phase by engaging the first reference surface of the positioning part with the engagement surface of the shaft member.

[0010] In the internal combustion engine, the positioning portion may have an insertion portion, the diameter of which is smaller than that of the portion of the positioning portion where the first reference surface is provided, located at a tip end closer to the shaft member than the first reference surface and inserted into the recess. That is, the insertion portion with a smaller diameter is inserted into the recess before the first reference surface is engaged with the engagement surface of the shaft member. This restricts the range of movement of the shaft member in the rotational direction to within the range in which the insertion portion can move relative to the recess, thereby enabling rough positioning of the shaft member in the rotational direction. That is, the first reference surface can be engaged with the engagement surface of the shaft member with a small positional misalignment between the insertion portion and the recess in the rotational direction of the shaft member, allowing for smooth engagement between the two. This reduces frictional force generated between the first reference surface and the engagement surface, suppressing wear on both. Therefore, the positioning portion can accurately position the shaft member to the reference phase over a long period of time. Furthermore, by making the diameter of the insertion portion smaller than the diameter of the portion where the first reference surface is provided, the insertion portion can be easily inserted into the recess.

[0011] In the above internal combustion engine, the engagement surfaces are provided on both sides of the shaft member in the rotational direction, and are inclined surfaces that are inclined in a direction in which the recess decreases in diameter from the outer side to the inner side in the radial direction of the shaft member, and the first reference surfaces are provided at positions corresponding to both sides of the shaft member in the rotational direction, and are inclined surfaces that are inclined in a direction in which the positioning portion decreases in diameter toward the tip side of the positioning portion on the shaft member side. By engaging the shaft member and the positioning portion at their inclined surfaces, the shaft member can be positioned to the reference phase with high accuracy.

[0012] The internal combustion engine can be the internal combustion engine according to claim 1, having valve trains corresponding to the cylinders, wherein the rotation of the single shaft member or the rotation of multiple shaft members as a unit transmits driving force to the valve trains of the cylinders, and the positioning mechanism engages with the shaft member at a position corresponding to the cylinder closest to the drive source, thereby preventing adverse effects caused by twisting of the shaft member.

[0013] The internal combustion engine may have a bearing that rotatably holds the shaft member, and the positioning mechanism may be supported by the bearing. Because the positioning accuracy between the bearing and the shaft member is high, by providing the positioning mechanism on the bearing, the positioning mechanism can accurately position the shaft member to the reference phase.

[0014] The present invention also provides a method for determining the rotational phase of a shaft member, characterized in that a shaft member rotated by a drive source is engaged with a positioning mechanism in the rotational direction of the shaft member, thereby positioning the shaft member to a reference phase that serves as a reference for displacement in the rotational direction. This allows the shaft member to be positioned to the reference phase with high precision. [Effects of the Invention]

[0015] According to the present invention, the shaft member can be accurately positioned at the reference phase. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front view showing a swing arm and its surrounding area of ​​an internal combustion engine according to an embodiment of the present invention. [Figure 2] 10A and 10B are diagrams illustrating the movement of the swing arm along the cam. [Figure 3] FIG. 2 is a diagram showing a state in which an actuator and rotary shafts of a plurality of cylinders are connected to each other. [Figure 4] 10A and 10B are diagrams showing the opening and closing timing of the valves changed by the rotation of the rotary shaft. [Figure 5] FIG. 4 is a view seen from the direction of arrow A in FIG. 3. [Figure 6] (a) to (d) are diagrams showing the insertion hole and the bolt, where (a) is a diagram showing the bolt before it is inserted into the insertion hole, (b) is a diagram showing the bolt being guided, (c) is a diagram showing the bolt being inserted into the insertion hole, and (d) is a diagram showing the bolt inserted into the insertion hole and positioned. [Figure 7] 10A and 10B are diagrams illustrating modified examples of the positioning portion. [Figure 8] 10A and 10B are diagrams showing modified examples of the recess and the positioning portion. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0018] 1 shows a valve train 1 as a shaft device according to one embodiment of the present invention. The valve train 1 is provided in an engine 100 as an internal combustion engine, and opens and closes intake valves or exhaust valves provided in the engine 100.

[0019] As shown in FIG. 1, the valve train 1 has a swing arm 2 and a push rod 10. The swing arm 2 is rotatable around an eccentric shaft 3. The push rod 10 is attached to a receptacle 2c provided at one end 2a of the swing arm 2. A roller 4 provided on the side of one end 2a of the swing arm 2 abuts against a cam 5. As the cam 5 rotates and changes the surface that abuts against the roller 4, the swing arm 2 rotates around the rotation center 3a of the eccentric shaft 3, and the one end 2a side swings up and down. As a result, the push rod 10 connected to one end 2a of the swing arm 2 moves up and down, opening and closing the corresponding valve.

[0020] The other end 2 of the swing arm 2 b On the side, a rotation shaft 6 is provided as a rotatable shaft member. The center of rotation 3a of the eccentric shaft 3 of the swing arm 2 is located at a position offset from the center of rotation of the rotary shaft 6. As shown in FIG. 2, due to the rotation of the rotary shaft 6, the swing arm 2 moves left and right in FIG. 2 along the outer peripheral surface of the cam 5 (for example, from the position indicated by the solid line to the position indicated by the dotted line in FIG. 2). This changes the position of the cam 5 with which the roller 4 abuts, changing the timing at which the swing arm 2 swings up and down. This changes the timing at which the push rod 10 moves up and down, making it possible to change the timing at which the valve opens and closes.

[0021] As shown in Figure 3, the rotary shafts 6 provided on the valve trains 1 of the cylinders are connected via connecting members. In this embodiment, the rotation of the rotary shafts 6 rotates only the swing arm 2 on the intake side, and only the opening and closing timing of the valves on the intake side is changed. However, the opening and closing timing of the valves on the exhaust side may also be changed. of These rotating shafts 6 rotate integrally when a driving force is transmitted from an actuator 7 serving as a driving source. The control unit of the valve gear 1 recognizes the current rotational phase of the rotating shaft 6. Therefore, the control unit of the valve gear 1 operates the actuator 7 in accordance with the load required of the engine, causing the rotating shaft 6 to rotate, and can change the opening and closing timing of the valves to the desired timing.

[0022] FIG. 4 shows the change in intake valve opening and closing timing as an example of changing the valve opening and closing timing by moving the swing arm 2. The horizontal axis of FIG. 4 shows the rotation angle of the cam 5, and the vertical axis shows the opening amount of the intake valve. The solid line in FIG. 4 shows the opening and closing timing in the initial state. death The dashed line in FIG. 4 shows the case where the opening and closing timing is shifted. θ degrees and is positioned at top dead center.

[0023] As shown in Figure 4, the timing at which the valve opens relative to the rotation angle of the cam 5 is changed by β before and after the change. In other words, before the change, the valve begins to open at angle α of the cam 5, whereas after the change, it begins to open at angle α-β, which is an angle β earlier. Note that angle θ indicates the top dead center of the cam 5. In this way, the opening and closing timing of the valve can be changed by rotating the rotary shaft 6.

[0024] In such a valve train 1, if the power supply to the valve train 1 is suddenly stopped due to a power outage or the like, the control unit of the valve train 1 will lose track of the current rotational phase of the rotating shaft 6, that is, the current horizontal position of the swing arm 2. As a result, if this continues, the device will no longer be able to change the opening and closing timing of the valve to the desired timing.

[0025] FIG. 5 is a view seen from the direction of arrow A in FIG. 3, and shows a state in which the rotation phase of the rotary shaft 6 has been positioned to the reference phase by the positioning mechanism 20. In FIG.

[0026] 5, a rotary shaft 6 is provided to pass through the intake side swing arm 2A and the exhaust side swing arm 2B. Bearings 8A and 8B are provided adjacent to the swing arms 2A and 2B on the axial outside thereof, respectively.

[0027] In this embodiment, a positioning mechanism 20 can be attached to and detached from the bearings 8A and 8B. The positioning mechanism 20 has a support member 21 that bridges the bearings 8A and 8B, and a bolt 22 as a positioning member that is provided in a hole in the support member 21 and can advance and retreat. The support member 21 is supported by the bearings 8A and 8B by screwing both ends of the support member 21 to the bearings 8A and 8B, respectively. An insertion hole 6a as a recess into which the bolt 22 can be inserted is provided at a predetermined position in the circumferential direction at the axial center of the rotating shaft 6. The insertion hole 6a is a recess that is recessed radially inward of the rotating shaft 6. The radial direction of the rotating shaft 6 refers to each direction toward the center of the rotating shaft 6 and the opposite direction on a plane perpendicular to the axial direction of the rotating shaft 6.

[0028] The cross section of the central side of the rotating shaft 6, where the insertion hole 6a is provided, is rectangular, and the insertion hole 6a is provided on one side of the rectangular cross section. When aligning the phase of the rotating shaft 6, first, the support member 21 is screwed to the bearings 8A and 8B. Then, the rotating shaft 6 is rotated by, for example, applying a wrench to the central side of the rotating shaft 6, so that the insertion hole 6a faces the bolt 22. In this embodiment, a rotating shaft 6 other than the rotating shaft 6 to which the positioning mechanism 20 is attached is rotated by applying a wrench. Then, the bolt 22 is protruded toward the rotating shaft 6 and inserted into the insertion hole 6a. This allows the rotating shaft 6 to be positioned at the reference phase, which serves as a reference for displacement in the rotational direction. As described above, by positioning the rotating shaft 6 using the positioning mechanism 20, the rotating shaft 6 can be mechanically positioned at the reference phase. In this state, the control unit of the valve train 1 is made to recognize that the rotating shaft 6 is positioned at the reference phase. As described above, the control unit of the valve train 1 can recognize the current rotational phase of the rotating shaft 6. However, the position where the insertion hole 6a is provided and the shape of the rotary shaft 6 are not limited to those in this embodiment.

[0029] Next, a phase determination method for inserting the bolt 22 into the insertion hole 6a and positioning the rotating shaft 6 at the reference phase in the valve train of this embodiment will be described in detail with reference to Figures 6(a) to 6(d). Figures 6(a) to 6(d) are enlarged views of the insertion hole 6a and the tip of the bolt 22, showing how the tip of the bolt 22 is inserted into the insertion hole 6a of the rotating shaft 6. Note that the direction of the double-headed arrow C in Figure 6(a) is the rotation direction of the rotating shaft 6, and Figures 6(a) to 6(d) are shown from a different direction than Figure 5.

[0030] As shown in Figure 6(a), the rotating shaft 6 has an engagement surface 6a1, which is a surface that forms the insertion hole 6a, on the entrance side of the insertion hole 6a. The engagement surface 6a1 is an inclined surface that is inclined in the direction in which the diameter of the insertion hole 6a decreases from the entrance side to the back side of the insertion hole 6a, that is, from bottom to top in Figure 6(a). In other words, it is an inclined surface that is inclined in the direction in which the diameter of the insertion hole 6a decreases from the outside to the inside in the radial direction of the rotating shaft 6.

[0031] The bolt 22 has a first reference surface 22a that engages with the engagement surface 6a1. The first reference surface 22a is an inclined surface that is inclined toward the tip of the side where the bolt 22 is inserted into the rotating shaft 6, that is, from bottom to top in FIG. 6(a), in a direction in which the diameter of the bolt 22 decreases. In other words, the first reference surface 22a is an inclined surface with a shape that corresponds to the engagement surface 6a1 of the rotating shaft 6. The engagement of the first reference surface 22a with the engagement surface 6a1 positions the rotating shaft 6 at the reference phase (see FIG. 6(d)). The bolt 22 also has an insertion portion 22c on the tip side closer to the rotating shaft 6 than the first reference surface 22a. The insertion portion 22c has a diameter B2 that is smaller than the diameter B1 of the base portion of the first reference surface 22a and the diameter B3 of the insertion hole 6a.

[0032] By providing the small-diameter insertion portion 22c on the bolt 22 closer to the tip than the first reference surface 22a, the first reference surface 22a can be smoothly engaged with the engagement surface 6a1, and wear on the first reference surface 22a and the engagement surface 6a1 can be suppressed. That is, by inserting the insertion portion 22c into the insertion hole 6a before engaging the engagement surface 6a1 with the first reference surface 22a, the bolt 22 can be roughly positioned relative to the insertion hole 6a in the rotational direction of the rotary shaft 6 (see FIG. 6(c)). In particular, in this embodiment, the diameter B2 of the insertion portion 22c is slightly smaller than the diameter B3 of the insertion hole 6a, and the bolt 22 is positioned with a play corresponding to this dimensional difference in the rotational direction of the rotary shaft 6. Then, by engaging the first reference surface 22a with the engagement surface 6a1 with a small positional misalignment between the bolt 22 and the insertion hole 6a, the frictional force generated between the first reference surface 22a and the engagement surface 6a1 can be reduced, allowing for smooth engagement between the two. This makes it possible to suppress wear on the first reference surface 22a and the engagement surface 6a1, and to improve the positioning accuracy of the bolt 22 with respect to the rotating shaft 6, i.e., the accuracy of positioning the rotating shaft 6 at the reference phase, over a long period of time. Furthermore, because the diameter B2 of the insertion portion 22c is smaller than the diameter B1 of the first reference surface 22a and the diameter B3 of the insertion hole 6a, the operation of inserting the insertion portion 22c into the insertion hole 6a is also facilitated. In other words, there is a greater dimensional difference between the insertion hole 6a and the insertion portion 22c than between the portion of the bolt 22 having the first reference surface 22a and the portion of the engagement surface 6a1 of the insertion hole 6a, and this dimensional difference makes it easier to insert the insertion portion 22c into the insertion hole 6a.

[0033] Particularly in this embodiment, a second reference surface 22b is provided at the tip of the insertion portion 22c. The second reference surface 22b is an inclined surface having an inclination in the same direction as the first reference surface 22a, and is an inclined surface inclined in the direction in which the diameter of the tip portion of the bolt 22 decreases toward the tip side on the side where the bolt 22 is inserted into the rotation shaft 6, that is, from bottom to top in FIG. 6(a). The first reference surface 22a and the second reference surface 22b in this embodiment are provided circumferentially.

[0034] The second reference surface 22b is a guide surface that guides the bolt 22 when it is inserted into the insertion hole 6a. Providing the second reference surface 22b on the insertion portion 22c allows the insertion of the insertion portion 22c into the insertion hole 6a to be performed smoothly. That is, as shown in FIG. 6(b), even if the bolt 22 is inserted while misaligned with respect to the insertion hole 6a, the second reference surface 22b of the bolt 22 abuts against the engagement surface 6a1 on the rotating shaft 6 side and moves along the engagement surface 6a1 (see the arrow in FIG. 6(b)), thereby guiding the bolt 22 in the direction of insertion into the insertion hole 6a. In particular, by providing the engagement surface 6a1 and the first reference surface 22a on both sides of the rotational direction of the rotating shaft 6, the bolt 22 can be guided to move relatively toward the insertion hole 6a, even if the bolt 22 is misaligned in either rotational direction with respect to the insertion hole 6a. This also reduces the frictional force generated between the insertion portion 22c and the engagement surface 6a1, thereby suppressing wear on the engagement surface 6a1.

[0035] Then, as shown in FIG. 6(c), the bolt 22 is guided by the second reference surface 22b and the insertion portion 22c is inserted into the insertion hole 6a.

[0036] Further, by inserting the bolt 22 into the insertion hole 6a, the first reference surface 22a of the bolt 22 engages with the engagement surface 6a1, as shown in FIG. 6(d).

[0037] By engaging the first reference surface 22a with the engagement surface 6a1, the rotating shaft 6 can be reliably positioned at the reference phase, thereby enabling the actual rotational phase of the rotating shaft 6 to be aligned with the phase recognized by the device.

[0038] The rotary shafts 6 of the valve trains 1 provided for each cylinder rotate integrally. Therefore, it is sufficient that the insertion hole 6a for inserting the bolt 22 of the positioning mechanism 20 is provided in at least one of the rotary shafts 6. In this embodiment, the insertion hole 6a is provided in the rotary shaft 6 closest to the actuator 7 (see FIG. 1 ), and the positioning by the positioning mechanism 20 is performed on this rotary shaft 6. Note that a single rotary shaft 6 may be provided across each cylinder, and this rotary shaft 6 may transmit driving force to the swing arm 2 of each cylinder, moving the swing arm 2 along the outer peripheral surface of the cam. Even in this case, the insertion hole 6a for inserting the bolt 22 may be provided at any position in the axial direction of the rotary shaft 6. For example, it may be provided at a position in the axial direction of the rotary shaft 6 corresponding to the valve train 1 closest to the actuator 7.

[0039] Furthermore, by supporting the positioning mechanism 20 on the bearings 8A and 8B, the positioning accuracy of the positioning mechanism 20 relative to the rotating shaft 6 can be improved. In other words, the positioning accuracy of the bearings 8A and 8B relative to the rotating shaft 6 that they support is higher than that of other members within the valve train 1. For this reason, by providing the positioning mechanism 20 on the bearings 8A and 8B as in this embodiment, the rotating shaft 6 can be positioned at the reference phase with high positional accuracy. However, the positioning mechanism 20 may also be provided on other members.

[0040] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0041] In the above embodiment, the positioning portion of the positioning mechanism is inserted radially into the recess provided in the shaft member and engages with the shaft member in the rotational direction, but for example, the positioning portion may be inserted axially into the recess provided in the shaft member and engage with the shaft member in the rotational direction. Also, the positioning portion does not necessarily have to be inserted into the recess of the shaft member.

[0042] In the above embodiment, the first reference surface 22a and the engagement surface 6a1 are circumferentially shaped as a truncated cone with a constant inclination angle. However, they may also be shaped as a truncated pyramid, for example. Furthermore, while the first reference surface 22a and the engagement surface 6a1 are circumferentially arranged, the engagement surfaces 6a1 may be arranged only on both sides of the rotational direction of the rotating shaft 6, and the first reference surfaces 22a may be arranged at positions corresponding to both sides of the rotational direction of the rotating shaft 6, i.e., at positions corresponding to the respective engagement surfaces 6a1, so that the two engage with each other only on both sides of the rotational direction. Furthermore, the first reference surface 22a and the engagement surface 6a1 may be arranged only on one side of the rotational direction, so that they engage with each other only on one side of the rotational direction. The configuration of the recess and positioning portion of the present invention is not limited to the above embodiment. For example, the bolt 23 serving as the positioning portion shown in FIG. 7 has only a surface 23a as an inclined surface. The surface 23a functions, for example, as a guide surface. The vertical surface 23b continuous with the surface 23a engages with the vertical surface 6a2 (see FIG. 6(a)) that forms the insertion hole 6a, and the bolt 23 fits into the insertion hole 6a, thereby positioning the rotating shaft 6 at the reference phase. In this case, the radial gap between the two is set smaller than in the embodiment shown in FIG. 6 so that the bolt 23 fits into the insertion hole 6a. Alternatively, the positioning portion may not have a guide surface like the surface 22b in FIG. 6 or the surface 23a in FIG. 7. Alternatively, the surface 23a in FIG. 7 may engage with the surface 6a1 of the insertion hole 6a. In the embodiment shown in FIG. 8, a recess 6b is provided on the rotating shaft 6. An engagement surface 6b1 facing the recess 6b engages with the first reference surface 24a of the positioning portion 24 in the rotational direction of the rotating shaft 6. This positions the rotating shaft 6 at the reference phase.

[0043] In the above embodiment, a bolt was described as the positioning portion of the present invention, but the positioning portion may be a positioning portion that protrudes toward the shaft member due to the biasing force of a spring and engages with the shaft member, or conversely, a positioning portion that an operator causes to protrude toward the shaft member against the biasing force of the spring and engage with the shaft member. Furthermore, any other suitable positioning portion configuration may be adopted as long as it is capable of positioning the shaft member.

[0044] In the above embodiment, the positioning mechanism 20 is removed when the valve train 1 is used, but it may remain attached. Making the positioning mechanism 20 detachable prevents interference with other components, such as a cover member that covers the swing arm 2, and prevents problems with using the valve train 1.

[0045] In the above embodiment, the shaft member is manually rotated and positioned at the reference phase by the positioning unit, but the present invention is not limited to this. For example, after the power supply is restored, the shaft member may be rotated by the driving force of the drive source and positioned by the positioning mechanism, thereby placing the shaft member at the reference phase. [Explanation of symbols]

[0046] 1 Valve gear (shaft gear) 2 swingarm 6 Rotating shaft (shaft member) 6a Insertion hole (recess) 6a1 Engagement surface 7 Actuator (drive source) 8A, 8B bearings 20 Positioning mechanism 22 Bolt (positioning part) 22a 1st reference plane 22b 2nd reference plane 22c Insertion part 100 Engine (internal combustion engine)

Claims

1. A driving source; a shaft member that is rotationally driven by the drive source; an internal combustion engine comprising: a positioning mechanism that is detachable from an internal combustion engine configured to be operable, and that is removed when a valve operating mechanism for opening and closing an intake valve or an exhaust valve in the internal combustion engine is used, the positioning mechanism engaging with the shaft member in its rotational direction to position the shaft member at a reference phase that serves as a basis for displacement in the rotational direction.

2. The shaft member has a recess recessed in its radial direction and an engagement surface forming the recess, the positioning mechanism has a positioning portion, 2. The internal combustion engine according to claim 1, wherein the positioning portion has a first reference surface that engages with the engagement surface in the rotational direction of the shaft member and positions the shaft member at the reference phase.

3. 3. The internal combustion engine according to claim 2, wherein the positioning portion has an insertion portion, the insertion portion being smaller in diameter than the portion of the positioning portion where the first reference surface is provided, at a tip end side closer to the shaft member than the first reference surface and being inserted into the recess.

4. The engagement surfaces are provided on both sides of the shaft member in the rotational direction, and are inclined surfaces inclined in a direction in which the recessed portion reduces in diameter from the outer side to the inner side in the radial direction of the shaft member, 3. The internal combustion engine according to claim 2, wherein the first reference surfaces are provided at positions corresponding to both sides of the shaft member in the rotational direction, and are inclined surfaces inclined in a direction in which the positioning portion reduces in diameter toward the tip side of the positioning portion on the shaft member side.

5. 2. An internal combustion engine according to claim 1, wherein the valve trains are each associated with a cylinder, a driving force is transmitted to the valve train of each cylinder by rotating a single shaft member or by rotating a plurality of shaft members together; 2. The internal combustion engine according to claim 1, wherein the positioning mechanism engages with the shaft member at a position corresponding to the cylinder closest to the drive source.

6. A method for determining the rotational phase of a shaft member of an internal combustion engine, characterized in that the shaft member is positioned at a reference phase that serves as a reference for displacement in its rotational direction by engaging, in the rotational direction of the shaft member, a shaft member that is rotationally driven by a drive source with a positioning mechanism that is detachable from the internal combustion engine configured to be operational and that is removed when using a valve gear for opening and closing an intake valve or an exhaust valve in the internal combustion engine.

Images