JP2017089514A - Manufacturing method of cam element member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a cam element member which can properly maintain a cam-part switching characteristic of the cam element member.SOLUTION: A manufacturing method of a cam element member in a dynamic valve device of an engine comprises: the cylindrical cam element member whose shaft member can be relatively displaced to an axial direction, which is attached to the shaft member so as to be rotatable integrally with the shaft member, and in which a plurality of cam parts aligned in the axial direction are arranged at an external peripheral face; and an operation device for moving the cam element member to the axial direction. The cam parts are switched by moving the cam element member to the axial direction by the operation device. The cam element member includes an end face cam having a lift part which outwardly protrudes in the axial direction, and the operation device includes a disc columnar operation member which is engaged with the lift part of the end face cam, and moves the cam element member to the axial direction. A cylindrical workpiece is prepared, a disc columnar rotating cutting tool having a diameter equal to that of the operation member is arranged along an end face of the workpiece so that its axial direction coincides with a radial direction of the workpiece, the cutting rotating tool is rotated, and the workpiece is rotated around its axis.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a method for manufacturing a cam element member.

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

  For example, Patent Document 1 discloses a camshaft that includes a shaft member and a cylindrical cam element member that is mounted on the shaft member in a state in which the shaft member can be relatively displaced in the axial direction and can rotate integrally with the shaft member. And an actuator for moving the cam element member in the axial direction, and by changing the positions of the plurality of cam portions provided on the cam element member by moving the cam element member in the axial direction, A valve operating apparatus is described in which a cam portion for opening and closing a valve is switched.

  In this valve operating apparatus, the actuator having the cylindrical operation pins that can be advanced and retracted (protruded / retracted) in the direction orthogonal to the axial direction is provided on both sides of the cam element member. The operation pin is selectively actuated (protruded) accordingly, and the cam pin is moved in the axial direction by sliding the operation pin to the end face cams provided at both ends of the cam element member in the axial direction. It is the structure which switches a part.

Japanese Patent Laying-Open No. 2015-59462

  Although not described in Patent Document 1, it is considered that the cam surfaces of the end face cams provided at both axial ends of the cam element member are formed by cutting using a cylindrical rotary cutting tool. Specifically, a cylindrical workpiece serving as a base for the cam element member is prepared, arranged along the workpiece end surface so that the axial direction of the rotary cutting tool coincides with the radial direction of the workpiece, and the rotary cutting tool is rotated. Cutting is performed by rotating the cam element member around its axis while rotating the cam element member.

  However, when the slope part (the part where the lift amount gradually increases from one side in the circumferential direction to the other side) is formed on the end face of the work as a part of the end face cam, the end face of the work is viewed from the front. In addition, the rotary cutting tool and the end face of the workpiece come into contact with each other at a position offset from the central axis of the rotary cutting tool in a direction perpendicular to the axis (lateral direction in front view). When the cam portion of the cam element member is switched by sliding the operation pin having a smaller diameter than the rotary cutting tool used for the machining on the cam surface of the end cam formed by such machining. In the operation pin, only a part in the axial direction of the portion facing the cam surface of the end cam contacts the cam surface (local contact), and as a result, the contact pressure between the operation pin and the cam surface of the end cam is excessive. However, the wear of the operation pin and the cam surface is promoted, the durability of the operation pin and the end surface cam is lowered, and there is a possibility that the cam portion switching characteristics of the cam element member cannot be properly maintained.

  In addition, since this rotary cutting tool has larger rigidity and becomes capable of more precise machining as the diameter increases, it is considered that a relatively large rotary cutting tool is used.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method of manufacturing a cam element member that can appropriately maintain the cam portion switching characteristics of the cam element member.

  In order to solve the above-described problems, the present invention provides a shaft member that rotates in response to a rotational force from a crankshaft, a relative displacement in the axial direction of the shaft member, and a single rotation with the shaft member. A cylindrical cam element member mounted on the shaft member and provided with a plurality of cam portions arranged in the axial direction on the outer peripheral surface, and an operating device for moving the cam element member in the axial direction, A method of manufacturing the cam element member in a valve operating apparatus for an engine that switches a cam portion used for opening and closing a valve by moving the cam element member in the axial direction by an operating device, wherein the cam element member includes: Including end face cams having lift portions projecting outward in the axial direction at both ends in the axial direction, and the operating device is located inside the outer peripheral surface of the cam element member; A cylindrical work member that includes a columnar operation member that moves the cam element member in the axial direction by engaging with the lift portion of the end face cam as it rolls is prepared, and a cylindrical work as a base of the cam element member is prepared A cylindrical rotary cutting tool having a diameter equivalent to the diameter of the operation member is disposed along the end surface of the workpiece such that the axial direction of the rotary cutting tool matches the radial direction of the workpiece, By rotating the cutting rotary tool around the axis of the cutting rotary tool and cutting the end face of the workpiece while rotating the workpiece relative to the cutting rotary tool around the axis of the workpiece, the end face Provided is a method of manufacturing a cam element member, characterized by forming a cam surface of a cam.

  The “diameter equivalent to the diameter of the operation member” in the present invention includes both the case where the diameter is the same as the diameter of the operation member and the case where the diameter of the operation member is slightly different.

  According to the present invention, the cam surface of the end face cam is formed using a rotary cutting tool having a diameter equivalent to the diameter of the operation member. The operation member (an operation member having the same diameter as the rotary cutting tool) was brought into sliding contact with the cam surface of the end face cam formed by such processing, and the cam portion switching operation of the cam element member was performed. In this case, since the cam surface contacts substantially the entire axial direction of the portion of the operation member facing the cam surface of the end cam, the contact pressure between the operation pin and the cam surface is suppressed from being excessively increased. The durability of the operation member and the end face cam can be ensured, and the cam portion switching characteristics of the cam element member can be appropriately maintained.

  In the present invention, when the diameter of the operation member is R1 and the diameter of the rotary cutting tool is R2, the value of R1-R2 is preferably in the range of −0.5 mm to 0.5 mm.

  According to this configuration, the durability of the operation member and the end face cam can be ensured more reliably, and the cam portion switching characteristics of the cam element member can be more appropriately maintained.

  In the present invention, the engine includes an intake-side cam portion switching mechanism having the cam element member mounted on the intake-side camshaft that drives the intake valve and the operating device, and an exhaust-side camshaft that drives the exhaust valve. It is preferable that the multi-cylinder engine includes at least one of an exhaust side cam portion switching mechanism having the cam element member and the operating device.

  According to this configuration, the switching characteristic of the cam element member in each cylinder of the multi-cylinder engine can be appropriately maintained.

  As described above, according to the manufacturing method of the cam element member according to the present invention, the cam portion switching characteristic can be appropriately maintained, and the cam element member can be manufactured.

It is a side view showing a schematic structure of a valve gear provided with a cam element member concerning an embodiment of the present invention. It is a front view which shows the valve operating apparatus by the x direction arrow in FIG. It is an expanded sectional view by the y-y line in FIG. It is a side view which shows the state which switched the cam part which opens and closes a valve from the state of FIG. It is a single-piece | unit perspective view of a cam element member. (A) is a front view of the cam element member of the first cylinder, and (b) is a rear view of the cam element member of the first cylinder. It is a longitudinal cross-sectional view of an operating device. It is a figure which shows a mode that the cam element member which concerns on embodiment of this invention is manufactured, (a) sees a mode that the end surface of a cylindrical workpiece | work is cut with the rotary cutting tool of diameter 5mm from the axial direction of a workpiece | work. (B) is the figure which looked at a mode that the end surface of a cylindrical workpiece | work was cut with the rotary cutting tool of diameter 20mm from the axial direction of the workpiece | work. It is the figure which looked at the mode of cutting shown to (a) and (b) of Drawing 8 from the direction of an axis of a rotary cutting tool. 8A shows a state in which an operation pin having a diameter of 5 mm is brought into sliding contact with the cam surface of the end face cam of the cam element member manufactured by the cutting process shown in FIG. 8A from the axial direction of the operation pin. (B) is the figure which looked at the contact area of the cam element member and operation pin in (a) from the axial direction of the cam element member. 8A shows a state in which an operation pin having a diameter of 5 mm is brought into sliding contact with the cam surface of the end face cam of the cam element member manufactured by the cutting process shown in FIG. 8B from the axial direction of the operation pin. (B) is the figure which looked at the contact area of the cam element member and operation pin in (a) from the axial direction of the cam element member. It is a figure which shows the contact pressure (contact pressure when changing the rotation angle of a cam element member) when making an operation pin slide-contact with the cam surface of a cam element member.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In the following description, first, the configuration of the valve gear including the cam element member according to the embodiment of the present invention will be described.

(Schematic configuration of valve gear)
FIG. 1 is a side view showing a schematic configuration of a valve gear including a cam element member according to an embodiment of the present invention. In the following description, unless otherwise specified, the cylinder row direction is the front-rear direction, the first cylinder 11 side is “front side”, and the fourth cylinder 14 side is “rear side”.

  In the present embodiment, an example in which the valve gear according to the present invention is applied to a four-cylinder, four-valve DOHC engine will be described, but the valve gear according to the present invention can also be applied to other engines.

  In this valve operating apparatus, a total of eight exhaust valves A ... A and these exhaust valves A ... A are attached in a closing direction to a cylinder head (not shown), two for each of the first to fourth cylinders 11-14. Return springs B ... B are provided. Further, this valve operating device is provided with a camshaft 2 that opens each exhaust valve A ... A against the urging force of the return springs B ... B via rocker arms C ... C at the upper part of the cylinder head. .

  The camshaft 2 includes vertical wall portions D ... D provided at the center positions of the cylinders 11 to 14 in the cylinder head and cap members E ... E attached to the upper portions of the vertical wall portions D ... D. Are rotatably supported by the bearing portions F... F, and are rotationally driven through a chain by a crankshaft (not shown).

  In addition, the camshaft 2 is spline-fitted to the shaft member 10 and the shaft member 10, and the first to fourth cam element members 201 to 204 that rotate integrally with the shaft member 10 and are movable in the axial direction. It consists of and. The cam element members 201 to 204 are arranged in a row on the shaft member 10 so as to correspond to the cylinders 11 to 14.

  Further, this valve operating apparatus includes six electromagnetically driven operating devices 301 to 306 for moving the cam element members 201 to 204 on the shaft member 10 in a predetermined stroke in the axial direction. Specifically, with the first cylinder 11 side of the cylinder row as the front, the first operating device 301 is located at the front end position of the cylinder row, and the second operating device 302 is located between the first and second cylinders 11 and 12. A third operating device 303 is located at the front end position between the second and third cylinders 12, 13, a fourth operating device 304 is located at the rear end position, and a fifth operating device 305 is located between the third and fourth cylinders 13, 14. The sixth operating device 306 is arranged at the rear end position of the cylinder row.

  As shown in FIG. 2, these operating devices 301 to 306 are arranged on the opposite side of the cam follower C ′ (see FIG. 2) of the rocker arm C with the cam shaft 2 interposed therebetween. (Corresponding to the “operation member” of the invention) is arranged so as to be directed to the axial center of the camshaft 2. In this embodiment, the operating devices 301 to 306 are attached to a cylinder head cover G that covers the camshaft 2 and the cam element members 201 to 204 from above.

  Each operation device 301 to 306 includes an electromagnetic actuator 3 and a substantially cylindrical operation pin 32 that can protrude from the electromagnetic actuator 3 when the electromagnetic actuator 3 is energized.

  The electromagnetic actuator 3 is a push-type solenoid actuator, and includes a columnar magnetic core 31, a cylindrical bobbin 34 attached to the peripheral surface of the magnetic core 31, and a coil wound around the outer peripheral surface of the bobbin 34. 33 and a cylindrical operation pin 32 (corresponding to the “operation member” of the present invention) that is provided coaxially with the magnetic core 31 and that can be approached / separated from the magnetic core 31 is slid in the axial direction. And a cylindrical pin support portion 35 that supports it.

  A cylindrical permanent magnet 36 is provided at the rear end portion (end portion on the magnetic core 31 side) of the operation pin 32.

  In the electromagnetic actuator 3, when the coil 34 is energized in a state where the distal end portion of the operation pin 32 is positioned at a retracted position (non-operating position) where it is retracted outside the outer peripheral surface of the cam element members 201 to 204, An electromagnetic force (repulsive force) in a direction away from the permanent magnet 36 is generated in the coil 34, whereby the operation pin 32 moves (projects) toward the shaft member 10. Specifically, the operation pin 32 is operated to enter the inner side of the outer peripheral surface of the cam element members 201 to 204 from the retracted position (non-operating position) where the operation pin 32 is located outside the outer peripheral surface of the cam element members 201 to 204. Move to position.

  Then, when the operation pin 32 is located at the operating position, the energization of the coil 34 is terminated, and when the shaft member 10 rotates in the forward direction while being in sliding contact with the return slope portion 23 described below at the tip of the operation pin 32, The operation pin 32 is guided by the return slope portion 23 and moves toward the retracted position. When the tip of the operation pin 32 reaches the vicinity of the top of the return slope portion 23, the permanent magnet 36 is attracted to the magnetic core 31 by the attractive force (magnetic force) acting between the permanent magnet 36 and the magnetic core 31, thereby The operation pin 32 moves to the retracted position and is held at this position.

  The energization of each cam element member 201 to 204 to the electromagnetic actuator 3 is based on a detection signal from a crank angle sensor (not shown), and an energization instruction from the ECU (Electronic Control Unit) (not shown) to the operation devices 301 to 306. Is done by.

  Further, in order to position the axial movements of the cam element members 201 to 204 by the operating devices 301 to 306 at two predetermined positions, FIG. 3 shows the first and second cam element members 201 and 202 as an example. In addition, a detent mechanism 40 is provided at a fitting portion between the shaft member 10 and each of the cam element members 201 to 204.

  The detent mechanism 40 is disposed in a hole 41 formed in the radial direction from the outer peripheral surface of the shaft member 10, a spring 42 accommodated in the hole 41, and an opening of the hole 41. 10 detent balls 43 urged so as to jump out from the outer peripheral surface of the radial direction in the radial direction, and two peripheral grooves 441 provided adjacent to the inner peripheral surface of the cam element members 201 to 204 in the axial direction, 442. In the detent mechanism 40, when the detent ball 43 is engaged with one circumferential groove 441, the cam element members 201 to 204 are in the first position shown in FIG. 1, and the detent ball 43 is in the other circumferential groove 442. The cam element members 201 to 204 are respectively positioned at the second positions shown in FIG.

  Here, as shown in FIG. 1, when all of the first to fourth cam element members 201 to 204 are located at the first position, the first cam element member 201 is rearward and the second cam element member 202 is frontward. The third cam element member 203 is located rearward and the fourth cam element member 204 is located forward. Therefore, the opposing end surfaces of the first and second cam element members 201 and 202 are close to each other, the opposing end surfaces of the second and third cam element members 202 and 203 are separated from each other, and the third and fourth cam element members 203, The opposing end surfaces of 204 are in a state of being close to each other.

  As shown in FIG. 4, when the first to fourth cam element members 201 to 204 are all located at the second position, the first cam element member 201 is forward and the second cam element member 202 is backward. The third cam element member 203 is located on the front side and the fourth cam element member 204 is located on the rear side. Therefore, the opposing end surfaces of the first and second cam element members 201 and 202 are separated from each other, the opposing end surfaces of the second and third cam element members 202 and 203 are close to each other, and the third and fourth cam element members 203, The opposing end surfaces of 204 are in a state of being separated from each other.

(Composition of cam element member)
Next, the configuration of the cam element members 201 to 204 will be described in more detail with reference to FIGS. 5 and 6 by taking the first cam element member 201 and the second cam element member 202 as an example.

  The cam element member 201 (202 to 204) has a cylindrical shape, and the outer peripheral surface of the intermediate portion is a journal portion 21 supported by the bearing portion F, and two exhaust valves A on the front and rear sides thereof. As shown in FIG. 5, for example, a first cam portion 221 having a large lift amount for low engine rotation and a high amount of lift are provided in each of the operation portions 22, 22. A second cam portion 222 having a small lift amount for rotating the engine is provided adjacent to each other.

  As shown in FIGS. 5 and 6 (b), the first cam portion 221 and the second cam portion 222 have a common base circle a and slightly nose portions b1 and b2 having different lift amounts on the base circle a. Are provided with a phase difference. The two operating parts 22 of the cam element members 201 (202 to 204) have the same order in which the first cam part 221 and the second cam part 222 are arranged in the front-rear direction, and the phases of the nose parts b1 match. The phase of nose part b2 is in agreement. The common base circle a means that the base circle diameter of the base circle a of the first cam portion 221 and the second cam portion 222 is the same.

  As shown in FIGS. 1 and 4, in the first cam element member 201 and the third cam element member 203, the first cam portion 221 is disposed on the front side, and the second cam portion 222 is disposed on the rear side. In the element member 202 and the fourth cam element member 204, the second cam portion 222 is disposed on the front side, and the first cam portion 221 is disposed on the rear side.

  When the cam element members 201 to 204 are positioned at the first position on the shaft member 10 by the detent mechanism 40 described above, the two first cam portions 221 and 221 are formed in any of the cam element members 201 to 204. The second cams are positioned corresponding to the cam followers C ′ and C ′ of the two rocker arms C and C of the corresponding cylinders 11 to 14 (see FIG. 1) and are positioned at the second position on the shaft member 10. The intervals between the operating portions 22 and 22 of the cam element members 201 to 204 are set so that the portions 222 and 222 are positioned corresponding to the cam followers C ′ and C ′ (see FIG. 4).

  In the engine according to the present embodiment, the explosion order of each cylinder is the third cylinder 13 → the fourth cylinder 14 → the second cylinder 12 → the first cylinder 11, and the cam elements 201 to 204 have the first order. The first to fourth cam elements so that the nose portions b1 and b2 of the first cam portion 221 and the second cam portion 222 are in sliding contact with the cam followers C ′ and C ′ in this order every 90 ° rotation of the camshaft 2. The members 201 to 204 are spline-fitted to the shaft member 10 with a phase difference from each other.

  Furthermore, each cam element member 201-204 is provided with end face cams 23, 23 at both front and rear direction ends.

  As shown in FIGS. 5 and 6, the end face cams 23 and 23 at both ends in the front-rear direction are respectively a reference surface 23a orthogonal to the axial direction of the cam element member 201 (202 to 204) and an axial direction from the reference surface 23a. And a lift part 23b protruding outward. As shown in FIG. 6, the lift portion 23 b is directed in the rotational direction X of the cam element members 201 to 204 within a predetermined phase range α (for example, about 120 °) from the lift start position e to the lift end position f. Accordingly, the lift amount in the axial direction gradually increases from the reference surface 23a (lift amount zero), and the lift amount is maximized at the lift end position f. The maximum lift amount is maintained in a range from the lift end position f to a slope end position g (described later) located in the rotation delay direction (the direction opposite to the rotation direction X), and the lift amount is zero at the slope end position g. The lift portion 26b is formed so as to be (return to the reference surface 26a).

  Further, as described above, each cam element member 201 to 204 is spline-fitted to the shaft member 10 with a predetermined phase difference according to the explosion order of the cylinders 11 to 14. The end face cams 23 and 23 of the element members 201 to 204 that face each other also face each other with a phase difference. In the present embodiment, as shown by reference numerals a and b in FIG. 1, the two adjacent first and second cam element members 201 and 202 and the third and fourth cam element members 203 and 204 face each other. The lift portions 23b and 23b of the end cams 23 and 23 are provided in different phases, and at least a part of the lift portions 23b and 23b overlaps in the axial direction when the two cam element members 201 to 204 are close to each other. Yes.

  The operation pins 32 and 32 of the second and fifth operation devices 302 and 305 operate by projecting between the opposing surfaces of the end cams 23 and 23 facing each other when the two corresponding cam element members 201 to 204 are close to each other. By moving to the position and engaging with these end face cams 23, 23, the two cam element members 201 to 204 which are close to each other are slid in a direction away from each other according to the rotation of the camshaft 2. Yes.

  In the state shown in FIG. 1, the first and second cam element members 201 and 202, and the third and fourth cam element members 203 and 204, which have been close to each other, are separated from each other so that they are all viewed from the first position. Move to the second position shown in FIG. In the state shown in FIG. 4, the second and third cam element members 202 and 203 that are close to each other move away from each other to move from the second position to the first position shown in FIG. 1.

  On the other hand, as shown in FIG. 4, the operation pin 32 of the first operating device 301 is in a state where the first cam element member 201 is in the second position on the front side, and the end cam 23 on the front side of the first cam element member 201. The first cam element member 201 is moved to the first position on the rear side with the rotation of the camshaft 2 as the camshaft 2 rotates. Similarly, the operating pin 32 of the fourth operating device 304 is moved to the operating position facing the front end cam 23 of the third cam element member 203 in a state where the third cam element member 203 is in the second position of the front. By projecting, the end face cam 23 is engaged, and the third cam element member 203 is moved to the rear first position as the camshaft 2 rotates.

  Further, the operation pin 32 of the third operating device 303 is an operating position that faces the rear end face cam 23 of the second cam element member 202 in a state where the second cam element member 202 is in the second position on the rear side. The end face cam 23 is engaged by being protruded to move to the first position on the front side. Similarly, the operation pin 32 of the sixth operating device 306 faces the end cam 23 on the rear side of the fourth cam element member 204 in a state where the fourth cam element member 204 is in the second position on the rear side. By projecting to the position, the end cam 23 is engaged and moved to the first position on the front side.

  Here, the protrusion of the operation pins 32 of the operation devices 301 to 306 to the operating position is performed at the following timing. That is, for the first and fourth operating devices 301 and 304, the reference surface 23a of the end face cam 23 of the front end face cam 23 of the first and third cam element members 201 and 203 is positioned at the pointing position of the operation pin 32. It is done at the timing. In the third and sixth operation devices 303 and 306, the reference surface 23a of the end face cam 23 on the rear side of the second and fourth cam element members 202 and 204 is located at the directing position of the operation pin 32. The operation pin 32 is projected at the timing. Further, in the second operating device 302, both reference surfaces 23a, 23a of the two end surface cams 23, 23 of the first and second cam element members 201, 202 facing each other at the directing position of the operating pin 32 are provided. The operation pin 32 is projected at the timing at which is positioned. In the fifth operating device 305, the reference surfaces 23a and 23a of the two end cams 23 and 23 of the third and fourth cam element members 203 and 204 facing each other are positioned at the directing position of the operation pin 32. The operation pin 32 is projected at the timing of the operation.

  Further, the movement of the cam element members 201 to 204 due to the protrusion of the operation pin 32 to the operating position corresponds to the cam follower C ′ of the rocker arm C corresponding to the base circle a of the first cam portion 221 or the second cam portion 222. It must be performed when it is positioned, that is, when the cylinder is in a stroke other than the exhaust stroke.

  Therefore, in order to satisfy these operating timing conditions, in this embodiment, as shown in FIG. 6, the rotational direction X with respect to the tops of the nose parts b1 and b2 of the first and second cam parts 221 and 222 is shown. A lift start position e of the end face cam 23 is set at a position of a predetermined phase on the front side of the end face, and the lift of the end face cam 23 is moved to a position of a predetermined phase α on the rear side (rotation delay direction) in the rotation direction X from the lift start position e. An end position f is set. And the lift part 23b of the end face cam 23 is provided so that the angle from the lift start position e of the end face cam 23 to the lift end position f toward the rear side in the rotation direction X is smaller than 180 degrees. In this case, in the positional relationship between the cam follower C ′ of the rocker arm C and the operation pins 32 of the operation devices 301 to 306 shown in FIG. 2, the cam element members 201 to 204 move soon after the end of the exhaust stroke.

  However, even if the nose parts b1 and b2 of the first and second cam parts 221 and 222 and the lift part 23b of the end face cam 23 are provided in the positional relationship as described above, the operation devices 301 to 306 may be If the operation pin 32 protrudes at an unintended timing, the operation pin 32 and the lift portion 23b may be inadvertently engaged. Therefore, in this embodiment, the return slope portion 23c for forcibly retracting the operation pin 32 protruding to the operating position to the inoperative position is integrally provided on the end face cam 23 of the cam element members 201 to 204. Yes.

  The place where the return slope portion 23c should be provided varies depending on conditions such as the order of switching the cam portions 22 of the cam element members 201 to 204, the number of the operation devices 30 arranged, and the like. However, regardless of these conditions, the return slope portion 23c is the opposite end of the cam element members 201 to 204 that are separated by the common operating devices 301 to 306 among the adjacent cam element members 201 to 204. It is necessary to provide at least the part. In the case of this embodiment, in order to switch the cam portions 22 of the cam element members 201 to 204 of the respective cylinders 11 to 14 in the order of the third cylinder 13 → the fourth cylinder 14 → the second cylinder 12 → the first cylinder 11 in the same combustion order. Return slope portions 23c are provided at the front and rear ends of the first and fourth cam element members 201 and 204, the rear end of the second cam element member 202, and the front end of the third cam element member 203, respectively.

  As shown in FIG. 5, the return slope portion 23 c further protrudes in the axial direction from the lift portion 23 b, and as shown in FIG. 6, on the end surface of the end face cam 23, the return delay portion 23 c is on the rotation delay side (arrow The cam surface is provided in a predetermined phase range in the direction opposite to X), that is, from the lift end position (slope start position) f to the slope end position g and extends outwardly inclined toward the rotation delay side, ie, rotation. The cam surface has a gradually increasing lift amount in the radial direction toward the delay side. The cam surface is slightly lower in lift amount at the slope start position f than the distal end portion of the operation pin 32 at the operating position, and more than the distal end portion of the operation pin 32 at the slope end position g in the inoperative position. Also set slightly lower.

  According to this return slope part 23c, after the movement of the cam element members 201 to 204 by the lift part 23b is finished, the operation pin 32 is inactivated from the operation position by sliding the tip part of the operation pin 32 against the cam surface. It can be retracted to the position. As described above, the lift amount at the slope end position g is lower than the tip of the operation pin 32 in the inoperative position, but is given to the operation pin 32 from the slope start position f to the slope end position g. The operating pin 32 is further pushed back to the inoperative position by the inertial force and the magnetic force of the electromagnetic actuator.

  Further, the cam element members 201 to 204 have, on the end face cam 23, a reverse slope return portion 23 d for forcibly retracting the operation pin 32 protruding to the operating position to the inoperative position when the camshaft 2 rotates in the reverse direction. It has one.

  The reverse slope portion 23d at the time of reverse rotation is provided together with the return slope portion 23c on the same end surface cam 23 as the end surface cam 23 provided with the return slope portion 23c among the end surface cams 23, 23 at both ends of the cam element members 201 to 204. It has been. In the case of this embodiment, the reverse return slope portion 23d includes the front and rear ends of the first and fourth cam element members 201 and 204, the rear end of the second cam element member 202, and the front end of the third cam element member 203. Are provided respectively.

  As shown in FIG. 5, the reverse slope portion 23d at the time of reverse rotation protrudes from the reference surface 23a in the axial direction by the same amount as the return slope portion 23c. Further, as shown in FIG. 6, the reverse slope return portion 23d has a predetermined phase range, that is, a slope end position (reverse rotation time) on the end face of the end face cam 23 on the rotation delay side (opposite to the arrow X) from the slope end position g. It is provided from a slope end position (g) to a slope start position h during reverse rotation. Then, the cam surface extending inwardly from the outer peripheral surface of the reverse slope end position g of the end face cam 23 toward the rotation delay side, that is, the cam in which the radial lift amount gradually decreases toward the rotation delay side. Has a surface. The cam surface is slightly lower in lift amount at the slope start position h at the time of reverse rotation than the distal end portion of the operation pin 32 at the operation position, and the operation pin 32 at which the lift amount at the slope end position g at the time of reverse rotation is in the inoperative position. It is set slightly lower than the tip.

  In the present embodiment, the four cam element members 201 to 204 respectively provided in the four cylinders 11 to 14 are operated by the six operating devices 301 to 306, and the cam portion 22 that opens and closes the exhaust valves A. The first cam portions 221... 221 having a small lift amount and the second cam portions 222.

(Method for manufacturing cam element member)
Next, a method for manufacturing the cam element member according to this embodiment will be described. Here, a method of forming the cam surface of the end face cam 23 (the reference surface 23a and the cam surface of the lift portion 23b) will be described.

  First, a cylindrical workpiece 60 serving as a base of the cam element member 201 (202 to 204) is prepared (see FIG. 8A). The workpiece 60 is a metal intermediate product manufactured by forging, and two cam portions (first cam portion 221 and second cam portion 222) are formed on the outer peripheral surface by forging (FIG. 8). (The illustration of the cam part is omitted.)

  Next, the cylindrical rotary cutting tool 4 a having a diameter equivalent to the diameter of the operation pin 32 is arranged along the end surface of the workpiece 60 so that the axial direction of the rotary cutting tool 4 a coincides with the radial direction of the workpiece 60. (See FIG. 8 (a)). In addition, the diameter (diameter) of the operation pin 32 is 5 mm as an example, and the diameter (diameter) of the rotary cutting tool 4a is also 5 mm. The rotary cutting tool 4a is, for example, an end mill that is rotationally driven by a motor (not shown).

  Next, while rotating the cutting rotary tool 4a around the axis of the cutting rotary tool 4a, the workpiece 60 is rotated around the axis of the workpiece 60 to cut the end surface of the workpiece 60, and the cam surface ( Reference surface 23a and cam surface of lift portion 23b) are formed.

  In addition, the code | symbol C1 of Fig.8 (a) has shown the center axis | shaft of the rotary cutting tool 4a, and this center axis | shaft C1 passes the center point O of the workpiece | work 60. FIG. In FIG. 8A, by rotating the workpiece 60 counterclockwise about the point O, the rotary cutting tool 4a is positioned relative to the workpiece 60 from a position indicated by a solid line from a position indicated by a two-dot chain line. Move to.

  In FIG. 8A and FIG. 9, the symbol La indicates the contact area between the rotary cutting tool 4a and the workpiece 60 when the rotary cutting tool 4a forms the lift portion 23b. As shown in FIGS. 8A and 9, the contact area La is at a position offset from the central axis C1 of the rotary cutting tool 4a in the direction perpendicular to the axis (the circumferential direction of the workpiece 60). This offset amount increases as the diameter of the rotary cutting tool increases. For example, in FIG. 8B, the diameter of the rotary cutting tool 4 b is 20 mm, which is four times the diameter of the operation pin 32. For this reason, the offset amount d2 in FIG. 8B is larger than the offset amount d1 in FIG. 8A (see FIG. 9).

  For this reason, as shown in FIG. 10A, when the operation pin 32 slides on the cam surface of the lift portion 23b formed by the rotary cutting tool 4a having a diameter of 5 mm, as shown in FIG. 10B. The cam surface is in contact with substantially the entire axial direction 32a in the portion of the operation pin 32 that faces the cam surface of the lift portion 23b. This is because the offset amount d1 (see FIGS. 8A and 9) from the central axis C1 of the rotary cutting tool 4a to the contact position between the rotary cutting tool 4a and the workpiece 60 is operated from the central axis P of the operation pin 32. This is because it matches the offset amount (see FIG. 10A, equal to the offset amount d1) up to the contact position 32a between the pin 32 and the cam surface. In addition, many straight lines L shown in FIG.10 (b) each show the contour line in a cam surface.

  Accordingly, an excessive increase in contact pressure between the operation pin 32 and the cam surface is suppressed, and as a result, the durability of the operation pin 32 and the end surface cam 23 is ensured, and the cam element member 201 (202 to 204). The cam portion switching characteristics can be appropriately maintained. As shown in the graph G1 (experimental result) in FIG. 12, the contact pressure between the operation pin 32 and the cam surface (the cam surface of the reference surface 23a and the lift portion 23b) is suppressed to a relatively low pressure of approximately 1000 MPa or less. ing. In FIG. 12, the angle 0 to 40 (deg) represents the range of the reference surface 23a, and the angle 40 to 120 (deg) represents the range of the lift portion 23b.

  On the other hand, as shown in FIG. 11A, when the operation pin 32 slides on the cam surface of the lift portion 23b formed by the rotary cutting tool 4b having a diameter of 20 mm, as shown in FIG. The cam surface is in contact with only a portion 32a in the axial direction of the portion of the operation pin 32 that faces the cam surface of the lift portion 23b. This is because the offset amount d2 from the central axis C2 of the rotary cutting tool 4b to the contact position Lb between the rotary cutting tool 4b and the workpiece 60 is the contact position 32a between the central axis P of the operation pin 32 and the operation pin 32 and the cam surface. This is because it does not match the offset amount up to (see FIG. 11A, which is equal to the offset amount d1).

  Therefore, in this case, the contact pressure between the operation pin 32 and the cam surface may be excessively increased. As a result, the durability of the operation pin 32 and the end face cam 23 may not be ensured. As shown in the graph G2 (experimental result) in FIG. 12, the contact pressure between the operation pin 32 and the cam surface (cam surface of the lift portion 23b) is a relatively high pressure of 3500 MPa.

(Operational effect of this embodiment)
According to the present embodiment, the cam surface of the end face cam 23 is formed using the rotary cutting tool 4 a having a diameter equivalent to the diameter of the operation pin 32. When the switching operation of the cam portions 221 and 222 of the cam element member 201 (202 to 204) is performed by sliding the operation pin 32 against the cam surface of the end face cam 23 formed by such processing. Since the cam surface contacts almost the entire axial direction of the portion of the operation pin 32 that faces the cam surface of the end face cam 23, the contact pressure between the operation pin 32 and the cam surface is suppressed from being excessively increased. As a result, the durability of the operation pin 32 and the end face cam 23 can be secured, and the cam portion switching characteristics of the cam element members 201 (202 to 204) can be appropriately maintained.

  Moreover, according to this embodiment, the switching characteristic of the cam element members 201-204 in each cylinder of a multi-cylinder engine can be maintained appropriately.

  In the above embodiment, the diameter of the operation pin 32 and the diameter of the rotary cutting tool 4a are set to be the same, but the diameter of the operation pin 32 and the diameter of the rotary cutting tool may be slightly different. Specifically, for example, when the diameter of the operation pin 32 is R1 and the diameter of the rotary cutting tool 4a is R2, even if the value of R1-R2 is within the range of −0.5 mm to 0.5 mm. Good. Moreover, as a more preferable range among the ranges, the value of R1-R2 may be in a range of not less than -0.2 mm and not more than 0.2 mm. Even within these ranges, an excessive increase in contact pressure between the operation pin 32 and the cam surface is suppressed, and the cam portion switching characteristics of the cam element members 201 (202 to 204) can be appropriately maintained. it can.

  In the above-described embodiment, the end surface of the workpiece 60 is cut while rotating the workpiece 60 around its axis, but the workpiece 60a is rotated while rotating the rotary cutting tool 4a around the axis of the workpiece 60 without rotating the workpiece 60. The end face of 60 may be cut.

4a Rotary cutting tool 10 Shaft member 23 End face cam 23c Lift part 32 Operation pin (operation member)
60 Work 201-204 Cam element member 221, 222 Cam part 301-306 Operating device

Claims (3)

A shaft member that rotates by receiving the rotational force from the crankshaft, and the shaft member is mounted on the shaft member so as to be capable of relative displacement in the axial direction and to rotate integrally with the shaft member. A cylindrical cam element member provided with a plurality of cam portions arranged in the direction, and an operating device for moving the cam element member in the axial direction. The operating device moves the cam element member in the axial direction. A method of manufacturing the cam element member in a valve operating device of an engine for switching a cam portion used for opening and closing a valve,
The cam element member includes end face cams having lift portions projecting outward in the axial direction at both ends in the axial direction, and the operating device is in a state of being inward of the outer peripheral surface of the cam element member. A cylindrical operation member that engages with a lift portion of the end face cam as the cam element member rotates and moves the cam element member in the axial direction;
Preparing a cylindrical workpiece as a base of the cam element member;
A cylindrical rotary cutting tool having a diameter equivalent to the diameter of the operation member is arranged along the end surface of the workpiece such that the axial direction of the rotary cutting tool matches the radial direction of the workpiece,
By rotating the cutting rotary tool around the axis of the cutting rotary tool and cutting the end surface of the workpiece while rotating the workpiece relative to the cutting rotary tool around the workpiece axis, A method of manufacturing a cam element member, comprising forming a cam surface of an end face cam.   The value of R1-R2 is in the range of not less than -0.5 mm and not more than 0.5 mm, where R1 is the diameter of the operating member and R2 is the diameter of the rotary cutting tool. The manufacturing method of the cam element member as described in any one of.   The engine includes an intake-side cam portion switching mechanism having the cam element member mounted on an intake-side cam shaft that drives an intake valve and the operating device, and the exhaust-side cam shaft that drives an exhaust valve. The method of manufacturing a cam element member according to claim 1 or 2, wherein the cam element member is a multi-cylinder engine provided with at least one of a cam element member and an exhaust side cam portion switching mechanism having the operating device.

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