Variable valve device

Abstract

Variable valve device (40) comprising: a camshaft (42, 52) which is rotatable in a cylinder head (3) of an internal combustion engine (E); a cam carrier (43, 53) comprising a cylindrical element that is axially displaceable about an outer circumference of the camshaft (42, 52), while its rotation with respect to the camshaft (42, 52) is prevented, wherein the cam carrier (43, 53) has a plurality of cam projections (43A, 43B, 53A, 53B) formed on an outer circumferential surface of the cam carrier (43, 53) and being adjacent to one another in an axial direction and having different cam profiles, wherein the cam carrier (43, 53) is integrated with a guide groove-cylindrical region (43D, 53D) which is provided with a guide groove (44, 54) defined like a channel by a groove bottom surface (G) and groove sidewall surfaces (F1, F2) on opposite sides of the groove bottom surface (G); and a cam switching mechanism (70, 80) which advances and retracts a switching pin (73, 74, 83, 84) so ​​that the switching pin (73, 74, 83, 84) is able to engage in the guide groove (44, 54) and release the engagement, wherein the cam carrier (43, 53) is guided and displaced in the axial direction during a rotation through the guide groove (44, 54) with the advanced switching pin (73, 74, 83, 84) engaged therein in order to switch the cam elevation (43A, 43B, 53A, 53B) which acts on a valve (41, 51), wherein a second groove sidewall surface (F1) of the groove sidewall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), which groove sidewall surface (F1) is brought into slidable contact with the switching pin (73, 74, 83, 84) and is pressed by it to move the cam carrier (43, 53), has a slidable sidewall surface (Faz) which extends from a sliding start tilting region (Pa), where the cam carrier (43) begins to move, through a sliding intermediate region (Pb) to a sliding end tilting region (Pz), where the cam carrier (43) ends to move, and the cam carrier (43, 53) is provided with a protective element (101, 102) which prevents the entry of the switching pin (73, 74, 83, 84) into the guide groove (44, 54) in a specific circumferential area (Zab) from a specific circumferential position (Yaa) in a rotational direction of the cam carrier (43, 53) slightly forward from the displacement start tilting area (Pa) to a circumferential position (Yb) in the sliding intermediate area (Pb) in a case in which the switching pin (73, 74, 83, 84) is active to enter and engage the guide groove (44, 54); wherein the protective element (101, 102) has a fixed side part (101a, 102a) which is fixed to the guide groove cylinder area (43D, 53D), and has a generally arc-shaped switching pin entry inhibiting part (101b, 102b) which is arranged in the guide groove (44, 54) in a certain circumferential area (Zab), wherein the fixed side part (101a, 102a) and the switching pin entry inhibiting part (101b, 102b) are continuous, and When the switching pin (73, 74, 83, 84) is advanced in a certain circumferential area (Zab), the switching pin entry inhibiting part (101b, 102b) comes into contact with the tip surface (73df) of the switching pin (73, 74, 83, 84) to prevent the switching pin (73, 74, 83, 84) from entering the guide groove (44, 54), and When the switching pin (73, 74, 83, 84) enters the guide groove (44, 54) in a circumferential region other than the defined circumferential region (Zab) in order to engage in the guide groove (44, 54), the switching pin entry inhibiting part (101b, 102b) moves into contact with the outer surface (73ds) of the switching pin (73, 74, 83, 84) to maintain a state in which the switching pin (73, 74, 83, 84) is engaged in the guide groove (44, 54); wherein In a case where the outer surface (73ds) of the switching pin (73, 74, 83, 84) which is engaged in the guide groove (44, 54) comes into contact with the switching pin entry inhibiting part (101b, 102b) of the protective element (101, 102), the switching pin entry inhibiting part (101b, 102b) is pressed and elastically deformed; characterized by the fact that the protective element (101, 102) is an elastic, generally arc-shaped, band-like element, the switching pin entry suppression part (101b, 102b) of the protective element (101, 102), which runs continuously from the fixed side part (101a, 102a), in the direction of a retraction side opposite a forward side in the direction of rotation of the cam carrier (43, 53), the fixed side part (101a, 102a) is attached to a groove side wall area (W2) which has a first groove side wall surface (F2) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), and the switching pin entry inhibiting part (101a, 102a) has a base area (101ba, 102ba) that extends continuously from the fixed side part (101a, 102a) and is in contact with the first groove side wall surface (F2) at the specified circumferential position (Yaa), which is slightly offset forward from the displacement start tilting region (Pa) in the direction of rotation of the cam carrier (43, 53), and the switching pin entry inhibiting part (101a, 102a) extends from the base area (101ba, 102ba) in the direction of the reset side opposite the advance side in the direction of rotation of the cam carrier (43, 53), while approaching the second groove side wall surface (F1) of the groove side wall surfaces (F1, F2), and a rear end area (101be, 102be) of the switching pin entry inhibition part (101a, 102a) is arranged in the sliding intermediate area (Pb).

Description

[0001] The present invention relates to switching operating characteristics of a variable transmission cable or a variable valve device of a valve in an internal combustion engine.

[0002] A variable valve device is known which has a cam carrier having a plurality of cam projections formed on an outer circumferential surface of the cam carrier and having different cam profiles that determine the characteristics of the valve operation, wherein the cam carrier is fitted axially displaceable about a camshaft, while rotation of it with respect to the camshaft is prevented, wherein a switching pin engaging in a guide groove is formed in the outer circumferential direction of the cam carrier, wherein the cam carrier is guided and displaced in the axial direction during rotation in order to change the cam projection acting on a valve in order to change the valve operation characteristics (see, for example, JP 2017 - 180 400 A).

[0003] Other technologies in this area include DE 10 2013 210 988 A1, DE 10 2009 007 819 A1, DE 10 2012 210 213 A1, DE 10 2013 220 559 A1, DE 10 2013 206 495 A1, and DE 10 2015 203 715 B3.

[0004] DE 10 2013 210 988 A1 shows a variable valve device according to the preamble of claims 1, 2 and 3 at least with the exception of the features which include and follow a displacement-tilt region where the cam carrier terminates the displacement.

[0005] DE 10 2009 007 819 A1 shows a variable valve device according to the preamble of claims 1, 2 and 3, at least with the exception of the features which include and follow the feature "slightly offset forward in a direction of rotation of the cam carrier".

[0006] DE 10 2012 210 213 A1, DE 10 2013 220 559 A1, DE 10 2013 206 495 A1 and DE 10 2015 203 715 B3 each show a variable valve device according to the preamble of claims 1, 2 and 3.

[0007] The guide groove formed in the outer circumferential surface of the cam carrier is a channel-shaped outer circumferential groove defined by a groove bottom surface and a groove sidewall surface on opposite sides of the groove bottom surface, and has a rectangular cross-section. The guide groove runs circumferentially while being bent axially, so that the switching pin engages in the guide groove to move the cam carrier axially.

[0008] The switching pin is advanced from a fixed position and engages in the guide groove, which rotates integrally with the cam carrier. Therefore, the switching pin must move forward and engage within a suitable time.

[0009] However, in a case where the engine speed increases to rotate the camshaft and cam carrier at high speed, the switching pin may fail to keep pace with the rotation and may be delayed in advancing and engaging the guide groove in the rotating cam carrier. When the tip of the switching pin then enters the guide groove, one of the groove's sidewall surfaces may collide with and make contact with the tip of the switching pin. This collision and contact can tilt the tip of the switching pin, causing it to slip out of the guide groove, and the switching pin may exhibit undesirable behavior, preventing reliable, smooth cam switching operation.

[0010] In view of these circumstances, an objective of the present invention is to provide a variable valve device in which the switching pin engages seamlessly in the guide groove despite an increased engine speed, instead of being tilted by the guide groove, which enables an improvement in the operability of the cam switching.

[0011] To achieve the objective, each aspect of the present invention provides a variable valve device comprising: a camshaft that is rotatable in a cylinder head of an internal combustion engine; a cam carrier comprising a cylindrical element axially displaceable about an outer circumference of the camshaft, while its rotation relative to the camshaft is prevented, wherein the cam carrier has a plurality of cam projections formed on an outer circumferential surface of the cam carrier and adjacent to each other in an axial direction, and having different cam profiles, wherein the cam carrier is integrated with a guide groove-cylinder area provided with a guide groove defined like a channel by a groove bottom surface and groove sidewall surfaces on opposite sides of the groove bottom surface; and a cam switching mechanism which advances and retracts a switching pin such that the switching pin is designed to engage in and disengage from the guide groove, wherein the cam carrier is guided and displaced during rotation in the axial direction through the guide groove with the engaged switching pin in it in order to switch the cam elevation which acts on a valve, wherein a second groove sidewall surface of the groove sidewall surfaces on the opposite sides of the guide groove, which groove sidewall surface is brought into slidable contact with the switching pin and is pressed by it to move the cam carrier, has a slidable sidewall surface that extends from a sliding start tilting region where the cam carrier begins to move, via a sliding intermediate region to a sliding end tilting region where the cam carrier ends to move, and The cam carrier is provided with a protective element that prevents the entry of the switching pin into the guide groove in a certain circumferential area from a certain circumferential position slightly forward in a rotational direction of the cam carrier from the displacement start tilting area to a circumferential position in the displacement intermediate area in a case where the switching pin is active to enter and engage the guide groove.

[0012] The second groove sidewall surface of the groove sidewall surfaces on the opposite sides of the guide groove, which is brought into slidable contact with the switching pin and pushed by it to move the cam carrier, has a slidable sidewall surface that extends from the displacement start tilt region, where the displacement of the cam carrier begins, through an intermediate displacement region to a displacement end tilt region, where the displacement ends. In a case where the switching pin is active to enter and engage the guide groove in the specific circumferential range from the specific circumferential position of the displacement start tilt region, slightly forward in the direction of rotation relative to the circumferential position in the intermediate displacement region, the slidable sidewall surface can come into collision and contact with the tip of the switching pin, tilting the switching pin so that it can slip out of the guide groove.

[0013] Thus, according to the present design, the cam carrier is provided with a protective element that prevents the switching pin from entering the specific circumferential area in the guide groove. This prevents the switching pin from being flicked away by the groove's side wall surface, thereby improving the operational reliability of the cam mechanism.

[0014] According to any aspect of the present invention The protective element has a fixed side part that is attached to the guide groove cylinder area and a circular arc-shaped switching pin entry inhibiting part that is arranged in the guide groove in the specified circumferential area, wherein the fixed side part and the switching pin entry inhibiting part are continuous, and When the switching pin is advanced within a certain circumferential range, the switching pin entry inhibiting part comes into contact with the tip surface of the switching pin to prevent the switching pin from entering the guide groove, and If the switching pin enters the guide groove in a different circumferential area than the specified circumferential area in order to engage the guide groove, the switching pin entry inhibiting part moves into contact with an outer surface of the switching pin to maintain a state in which the switching pin is engaged in the guide groove.

[0015] According to this design, the protective element comprises a generally arc-shaped switching pin entry inhibiting element, which is arranged in the guide groove within the specified circumferential area, and a switching pin entry inhibiting element that prevents the switching pin from entering the guide groove within the specified circumferential area. If the switching pin enters and engages in the guide groove within a circumferential area other than the specified area, the switching pin entry inhibiting element can move into contact with the outer surface of the switching pin to move the cam carrier while maintaining the engaged state of the switching pin in the guide groove. Thus, the protective element prevents the switching pin from tilting out of the guide groove.The protective element also moves to maintain the engagement state of the switching pin in the guide groove, thus preventing the switching pin from obstructing the movement of the cam carrier.

[0016] According to any aspect of the present invention In a case where the outer surface of the switching pin engaged in the guide groove comes into contact with the switching pin entry inhibiting part of the protective element, the switching pin entry inhibiting part is pressed and elastically deformed.

[0017] According to this design, if the outer surface of the switching pin engaged in the guide groove comes into contact with the switching pin entry inhibition part of the protective element, the inhibition part is compressed and elastically deformed. Thus, if the switching pin enters and engages the guide groove in a circumferential region other than the specified one, the inhibition part can be elastically deformed to maintain the engaged position of the switching pin. If contact of the switching pin's outer surface ends, the inhibition part can return to its original state due to its elasticity, thereby simplifying the structure.

[0018] According to a first aspect of the present invention The protective element is an elastic, generally arc-shaped, band-like element. The switching pin entry inhibition part of the protective element runs continuously from the stationary side part towards a reset side opposite a forward side in a rotational direction of the cam carrier, The fixed side part is attached to the groove side wall area, which has a first groove side wall surface of the groove side wall surfaces on the opposite sides of the guide groove, and The switching pin entry inhibiting part has a base area that extends continuously from the fixed side part and is in contact with the first groove side wall surface at the specified circumferential position of the displacement start tilting region, slightly offset forward in the direction of rotation of the cam carrier, and the switching pin entry inhibiting part extends from the base area towards the retraction side opposite the advancement side in the direction of rotation of the cam carrier, while approaching the second groove side wall surface of the groove side wall surfaces, and a rear end area of ​​the switching pin entry inhibiting part is arranged in the displacement intermediate region.

[0019] According to this design, the switching pin entry inhibition part of the protective element has a base area that contacts the first groove sidewall surface at a specific circumferential position, which is slightly forward of the displacement start tilting region in the direction of rotation. The switching pin entry inhibition part extends from the base area towards the retraction side, opposite the advancement side in the rotational direction of the cam carrier, as it approaches the second groove sidewall surface. A rear end area of ​​the switching pin entry inhibition part is located in the displacement intermediate region. Thus, the switching pin entry inhibition part is positioned in the guide groove within a specific circumferential region.The switching pin, which is operational enough to enter the guide groove within the specified circumferential range, rests at its tip face against an upper edge of the switching pin entry restrictor and is thus prevented from entering the guide groove. Conversely, if the switching pin enters and engages the guide groove in a region other than the specified circumferential range, the switching pin entry restrictor comes into contact with the outer surface of the switching pin engaged in the guide groove and is elastically deformed to clear a path for the switching pin to pass through. This allows the cam carrier to be displaced while maintaining the switching pin's engagement state in the guide groove.

[0020] According to a second aspect of the present invention The protective element is an elastic, generally arc-shaped steel wire element. is an outer circumferential surface of a groove sidewall region, which has the groove sidewall surface that partially has the displaceable sidewall surface of the guide groove cylinder region, with a circumferential groove that has an axial width between an area axially outside the displacement start tilting area through a width of the protective element and the displacement intermediate area and has a groove depth that is substantially equal to a radial thickness of the protective element, The switching pin entry inhibition part of the protective element, which runs continuously from the stationary side part, extends towards the reset side opposite the advance side in the direction of rotation of the cam carrier, and the protective element has an extension part that extends towards the reset side from the switching pin entry inhibition part. The fixed side part is fitted and fastened axially in a narrow circumferential groove section outside the displacement / tilting area of ​​the circumferential groove. The switching pin entry inhibiting part has a base area that extends continuously from the fixed side part and is in contact with the second groove side wall surface, which has the sliding side wall surface, at the specified circumferential position slightly forward of the sliding start tilting region in the direction of rotation of the cam carrier, wherein the switching pin entry inhibiting part leaves the base area and extends along a groove opening of the guide groove in the direction of rotation of the cam carrier towards the second groove side wall surface and towards the reset side relative to the advance side, and the switching pin entry inhibiting part has a rear area that extends continuously to the extension part and is in contact with the second groove side wall surface at the sliding intermediate region, and The extension part is inserted into a wide circumferential groove section, which corresponds to the movable side wall surface axially inwards from the displacement start inclination area of ​​the circumferential groove.

[0021] According to this design, the switching pin entry inhibition part of the protective element extends from the fixed side part, which is inserted axially into and attached to the narrow circumferential groove section outside the displacement-start inclination region of the circumferential groove, and towards the retraction side opposite the advancement side in the direction of rotation of the cam carrier. The switching pin entry inhibition part extends from the base area, which is in contact with the second groove side wall surface, which has the displaceable side wall surface, at a specific circumferential position slightly forward of the displacement-start inclination region in the direction of rotation. The switching pin entry inhibition part leaves the base area and extends to the second groove side wall surface and to the retraction side along the groove opening of the guide groove.The rear portion of the switching pin entry blocking element is in contact with the second groove sidewall surface at the sliding intermediate area. The extension, which runs continuously from the rear portion, is inserted axially inwards from the sliding start inclination area of ​​the circumferential groove into the wide circumferential groove section that corresponds to the sliding sidewall surface. Thus, the switching pin entry blocking element of the protective element projects into the groove opening of the guide groove within the specified circumferential area. Consequently, the switching pin, which is capable of entering the guide groove within the specified circumferential area, rests against the switching pin entry blocking element at the tip surface of the switching pin and is prevented from entering the guide groove.On the other hand, if the switching pin enters and engages in the guide groove in a different circumferential region than the specified one, the switching pin entry restrictor comes into contact with the outer surface of the switching pin engaged in the guide groove. The switching pin entry restrictor is thus elastically deformed to clear a path for the switching pin, allowing it to pass through and enabling the cam carrier to be displaced, while maintaining the switching pin's engagement state in the guide groove.

[0022] According to a third aspect of the present invention The protective element is an elastic, generally arc-shaped steel wire element. The switching pin entry inhibition part of the protective element, which runs continuously from the fixed side part, extends towards the reset side opposite the advance side in the direction of rotation of the cam carrier, The fixed side part is fitted and fastened in a fitting insertion groove formed in the groove side wall area, which has a first groove side wall surface of the groove side wall surfaces on opposite sides of the guide groove, and The switching pin entry inhibiting part has a base area that extends continuously from the fixed side part and is in contact with an outer circumferential edge of the first groove side wall surface at the specified circumferential position slightly forward of the displacement start tilting region in the direction of rotation of the cam carrier. The switching pin entry inhibiting part extends from the base area to the reset side opposite the advance side in the direction of rotation of the cam carrier along a groove opening of the guide groove as it approaches the second groove side wall surface of the groove side wall surfaces. The switching pin entry inhibiting part has a curved rear area that is arranged in the displacement intermediate area, with the tip of the rear area being in contact with the groove bottom surface.

[0023] According to this design, the switching pin entry inhibiting part of the protective element extends from the fixed side part, which is inserted into and attached to the fitting insertion groove formed in the groove side wall area that has the first groove side wall surface, towards the reset side opposite the advance side in the direction of rotation of the cam carrier. The switching pin entry inhibiting part extends from the base area, which is offset slightly forward at the specified circumferential position from the displacement start tilting area towards the reset side along the groove opening of the guide groove, as it approaches the second groove side wall surface. The curved rear section is located in the displacement intermediate area, and the tip of the rear section is in contact with the groove bottom surface of the guide groove.Thus, the switching pin entry prevention element of the protective element is arranged along the groove opening of the guide groove in a specific circumferential area that is unsuitable for the entry of the switching pin. Accordingly, the switching pin, which is capable of entering the guide groove in this specific circumferential area, rests against the switching pin entry prevention element at the tip surface of the switching pin and is prevented from entering the guide groove. On the other hand, if the switching pin enters and engages in the guide groove in a circumferential area other than the specific circumferential area, the switching pin entry prevention element comes into contact with the outer surface of the switching pin engaged in the guide groove.The switching pin entry inhibition part is thus elastically deformed to clear a path for the switching pin, allowing the switching pin to pass through here, allowing the cam carrier to be displaced, while maintaining the engagement state of the switching pin in the guide groove.

[0024] According to each aspect of the present invention, the cam carrier is provided with a protective element that prevents the switching pin from entering the guide groove within a certain circumferential area. This prevents the switching pin from being flicked away from the guide groove, allowing it to engage smoothly and thus improving the operability of the cam mechanism. Fig. Figure 1 is a general side view of a motorcycle in which an internal combustion engine having a variable valve device according to a first embodiment of the present invention is fitted. Fig. Figure 2 is a side view from the left of the internal combustion engine. Fig. Figure 3 is a top view of the internal combustion engine. Fig. Figure 4 is a side view from the left, showing the contours of the cylinder head and similar components in the internal combustion engine by means of lines with alternating long and two short strokes, exposing a major component of an internal valve mechanism. Fig. Figure 5 is a top view of an upper cylinder head, with a cylinder head cover removed from the cylinder head as seen from above. Fig. Figure 6 is a perspective view showing only the main components of an intake cam switching mechanism and an exhaust cam switching mechanism, with the intake cam switching mechanism and the exhaust cam switching mechanism partially omitted. Fig. Figure 7 is a perspective view of an intake-side shift drive shaft, to which a first shift pin and a second shift pin are attached. Fig. Figure 8 is a perspective view of an intake-side cam carrier. Fig. Figure 9 is a perspective view of different rotational states of the intake-side cam carrier. Fig. Figure 10 is a perspective view of a right-hand protective element. Fig. Figure 11 is a side view of the right protective element in one direction of an arrow XI in Fig. 10 considered. Fig. 12 is a development of guide grooves and protective elements in a guide groove cylinder area. Fig. Figure 13 is a development of guide grooves and protective elements that illustrates that the first switching pin elastically deformed the protective element. Fig. Figure 14 is a perspective view of an area of ​​a guide groove cylinder area of ​​an intake-side cam carrier according to a second embodiment. Fig. Figure 15 is a side view of an area of ​​the guide groove cylinder area. Fig. Figure 16 is a side view of another rotational state of the area of ​​the guide groove cylinder area. Fig. Figure 17 is a partial perspective cross-sectional view of the intake-side cam carrier. Fig. 18 is a development of guide grooves and protective elements in a guide groove cylinder area. Fig. Figure 19 is a development of guide grooves and protective elements, which shows that the first switching pin has elastically deformed the protective element. Fig. Figure 20 is a perspective view of an area of ​​a guide groove cylinder area of ​​an intake-side cam carrier according to a third embodiment. Fig. Figure 21 is a cross-sectional view of the intake side cam carrier and a guide groove cylinder area for an intake camshaft. Fig. 22 is a development of guide grooves and protective elements in a guide groove cylinder area. Fig. 23 is a development of the guide groove and the protective element, which shows that the first switching pin has elastically deformed the protective element. Fig. Figure 24 is a perspective view of an area of ​​a guide groove cylinder area of ​​an intake-side cam carrier according to a modified example of the third embodiment. Fig. Figure 25 is a cross-sectional view of the intake side cam carrier and a guide groove cylinder area for an intake camshaft. Fig. 26 is a development of guide grooves and protective elements in a guide groove cylinder area.

[0025] The following describes a first embodiment according to the present invention based on Fig. 1 to 13 described.

[0026] Fig. Figure 1 is a side view of a motorcycle 500, which is a vehicle of the saddle seat type, in which an internal combustion engine having a variable valve device according to an embodiment of the present invention is attached.

[0027] It should be emphasized that in the description and the claims, the directions forward, backward, right and left follow the normal criteria, whereby a straight-line direction of the motorcycle 500 according to the present embodiment corresponds to the direction forward, and that in the drawings FR indicates the forward direction, RR indicates the reverse direction, LH indicates the direction to the left and RH indicates the direction to the right.

[0028] A vehicle body frame of the motorcycle 500 has a right and left pair of main frames 503 branching laterally and extending obliquely rearward and downward from a head tube 502, holding a front fork 505 in a steerable manner which holds a front wheel 506 pivotably.

[0029] Front sections of the main frame 503 form engine suspension sections 503a which hang downwards, and rear sections of the main frame 503 are bent to form pivot frame sections 503b which extend downwards.

[0030] A seat rail 504 is connected to a rear part of the center of the pair of main frames 503 and extends to the rear.

[0031] A swing arm 508, having a front end which is pivotably held by a pivot shaft 507, extends from the pivot frame areas 503b to the rear, and a rear wheel 509 is pivotably held by a rear end of the swing arm 508.

[0032] A connecting mechanism 510 is provided between the swing arm 508 and each of the pivot frame areas 503b and a rear damping 511 is arranged between a part of the connecting mechanism 510 and the seat rail 504.

[0033] The body frame has a drive unit Pu, which is suspended between the engine mounting sections 503a and the pivot frame sections 503b of the main frame 503. A drive chain 514 runs between a drive pinion 512, which is fitted around an output shaft that is a countershaft of a gearbox M of the drive unit Pu, and a driven vehicle pinion 513, which is fitted around a rear axle of the rear wheel 509.

[0034] An air filter 522 is installed on one front half of the pair of main frames 503, and a fuel tank 516 is installed on one rear half of the pair of main frames 503. A main seat 517 and a passenger seat 518 are provided behind the fuel tank 516 and are held by the seat rail 504.

[0035] An internal combustion engine E, occupying a front half of the drive unit Pu, is a transversely mounted, water-cooled, four-stroke internal combustion engine attached to the vehicle body frame, with the cylinders correctly inclined forward.

[0036] A crankshaft 10 of the internal combustion engine E is pivotally held by a crankcase 1 and is aligned in a lateral direction with the vehicle body. The crankcase 1 has a gearbox M located behind the crankshaft 10.

[0037] With reference to Fig. 2 The internal combustion engine E has an engine body located on the crankcase 1 and has a cylinder block 2 in which four cylinders are arranged in a row, a cylinder head 3 connected to an upper part of the cylinder block 2 and a cylinder head cover 4 positioned on the upper part of the cylinder head 3.

[0038] A cylinder axis Lc, corresponding to a central axis of a cylinder opening in the cylinder block 2, is inclined forward, and the cylinder block 2, the cylinder head 3 and the cylinder cover 4, which are positioned on the top of the crankcase 1, extend upward from the crankcase 1 in a slightly forward-inclined orientation.

[0039] Furthermore, the oil pan 5 is provided under the crankcase 1 to curve downwards.

[0040] The crankcase 1 is vertically divided into an upper crankcase 1U and a lower crankcase 1L, wherein the crankshaft 10 is rotatably held around the shaft between the subdivision surfaces of the upper crankcase 1U and the lower crankcase 1L.

[0041] The crankcase 1 accommodates the transmission M behind the crankshaft 10, and a main shaft 11 and a countershaft 12, which form the transmission M, are aligned parallel to the crankshaft 10 in the body width direction (see Fig. 2).

[0042] In an action chamber of the crankcase 1, the main shaft 11 and the countershaft 12 of the transmission M are arranged parallel to the crankshaft 10 and aligned in a lateral and horizontal direction (see Fig. 3) The countershaft 12 runs through the crankcase 1 to the left and protrudes outwards to serve as the output shaft.

[0043] Intake pipes for the respective cylinders, which run from the rear of the cylinder head 3, are connected to the air filter 522 via a throttle valve 521 (see Fig. 1).

[0044] Furthermore, exhaust pipes 525 for the respective cylinders, which run from a front of the cylinder head 3, run downwards, bend backwards and run to the rear along a right side of the oil pan 5.

[0045] The present internal combustion engine E has a variable valve arrangement 40, which is provided in the cylinder head 3 and has an overhead twin camshaft (DOHC) structure with four valves.

[0046] The cylinder head 3 of the present internal combustion engine E is divided into two vertical areas in the axial cylinder direction (the axial direction of the cylinder axis Lc) and has a lower cylinder head 3L positioned on the cylinder block 2 and an upper cylinder head 3U positioned on the lower cylinder head 3L (see Fig. 2 and Fig. 4).

[0047] With reference to Fig. 4 The lower cylinder head 3L has two inlet openings 31i for each cylinder, which extend obliquely upwards from a combustion chamber 30 while bending backwards, and two outlet openings 31e, which extend forwards and bend.

[0048] The lower cylinder head 3L holds intake valves 41 and exhaust valves 51, which open and close the intake ports of the intake manifolds 31i to the combustion chamber 30 and the exhaust ports of the exhaust manifolds 31e to the combustion chamber 30, so that the intake valves 41 and the exhaust valves 51 can move back and forth synchronously with the rotation of the crankshaft 10.

[0049] The lower cylinder head 3L is integrally attached to the upper crankcase 1U by threaded bolts 7 together with the cylinder block 2 (see Fig. 4 and Fig. 5).

[0050] The upper cylinder head 3U, positioned on the lower cylinder head 3L, forms right-angled frame walls including the front side wall 3Fr and a rear side wall 3Rr, which are long in the lateral direction, and a left side wall 3Lh and a right side wall 3Rh, which are short in a front-to-rear direction.

[0051] The inner surface of the rectangular frame of the upper cylinder head 3U is divided into a right, narrow timing chain chamber 3c and a left valve chamber 3d by a support wall 3vr, which is formed along and parallel to the right side wall 3Rh. The valve chamber 3d is further divided into five chambers by four support walls 3v parallel to the right and left side walls 3Lh and 3Rh.

[0052] Each of the supporting walls 3v is arranged above the center of the combustion chamber 30 for the corresponding cylinder and has a spark plug insertion tube area 3vp, which is formed in the center of the support wall 3v in the direction from front to back, and through which a spark plug is inserted and fitted.

[0053] The variable valve assembly 40 has the cylinder head 3 and the cylinder head cover 4 and is provided in the valve chamber 3d.

[0054] With reference to Fig. 4 and Fig. 5 A lateral pair of intake valves 41 is provided in each of the inline four-cylinder engines, and four intake valves 41 are arranged in a row in the lateral direction. An intake-side camshaft 42 is arranged above the four intake valves 41 and oriented in the lateral direction, and is fitted in bearings 3vv in the support walls 3v and 3vr of the upper cylinder head 3U, the bearings 3vv forming semicircular arc-shaped surfaces. The intake-side camshaft 42 is rotatably held about the shaft between camshaft supports 33.

[0055] Similarly, a lateral pair of intake valves 51 is arranged in a row in the lateral direction for each cylinder, and four exhaust valves 51 are arranged in a row in the lateral direction. An exhaust-side camshaft 52 is arranged above the four exhaust valves 51 and oriented in the lateral direction, and is fitted in bearings in the support walls 3v and 3vr of the upper cylinder head 3U. The exhaust-side camshaft 52 is held rotatably about the shaft between the camshaft supports 33.

[0056] The exhaust-side camshaft 52 is arranged in front of and parallel to the intake-side camshaft 42.

[0057] With reference to Fig. Figure 5 shows that the intake-side camshaft 42 has a held section 42a located near the right end of the intake-side camshaft 42 and pivotably held by the support wall 3vr. The support wall 3vr is arranged between flanges on opposite sides of the held section 42a to position the intake-side camshaft 42 axially. On the left side of the held section 42a, a shaft key section 42b with external splined teeth formed on an outer circumferential surface of the shaft key section 42b extends a considerable distance by passing through four support walls 3v of the valve chamber 3d.

[0058] An intake-side driven gear 49 is fitted around the flange located at the right end of the intake-side camshaft 42 and protruding into the timing chain chamber 3c of the intake-side camshaft 42.

[0059] Similarly, the exhaust-side camshaft 52 has a retained section 52a located near the right end of the exhaust-side camshaft 52, which is rotatably held around the shaft by the support wall 3vr. The support wall 3vr is arranged between flanges on opposite sides of the retained section 52a to position the exhaust-side camshaft 52 axially. On the left side of the retained section 52a, a shaft key section 52b with external splines formed on an outer circumferential surface of the shaft key section 52b extends a considerable distance by passing through four support walls 3v of the valve chamber 3d.

[0060] An exhaust-side driven gear 59 is fitted around the flange located at the right end of the intake-side camshaft 52 and protruding into the timing chain chamber 3c of the exhaust-side camshaft 52.

[0061] Four intake-side cam carriers 43, corresponding to cylindrical elements, are arranged on the shaft keyway 42b of the intake-side camshaft 42 by being fitted in a wedge-like manner around the shaft keyway 42b.

[0062] The four intake-side cam carriers 43 are axially displaceable around the intake-side camshaft 42, while rotation relative to the intake-side camshaft 42 is prevented.

[0063] Similarly, four exhaust-side cam carriers 53, corresponding to cylindrical elements, are arranged on the keyway 52b of the exhaust-side camshaft 52 by being fitted around the keyway 52b in a keyed manner. The four exhaust-side cam carriers 53 are axially displaceable around the exhaust-side camshaft 52, while rotation relative to the exhaust-side camshaft 52 is prevented.

[0064] Fig. Figure 6 is a perspective view showing only the main components of an intake cam switching mechanism and an exhaust cam switching mechanism, with parts of the intake cam switching mechanism and the exhaust cam switching mechanism not shown.

[0065] Each of the intake-side cam carriers 43 has two pairs of high-speed-side cam lobes 43A and low-speed-side cam lobes 43B, which are formed around an outer circumferential surface of the intake-side cam carrier 43 and are adjacent to each other in the axial lateral direction, and have different cam profiles, and a held cylinder area 43C, which is arranged between the pairs of cam lobes 43A and 43B in the lateral direction and has a certain width in the axial direction; wherein the high-speed-side cam lobe 43A has a large lift amount and the low-speed-side cam lobe 43B has a small lift amount (see Fig. 8 and Fig. 9).

[0066] For the adjacent high-speed side cam elevation 43A and the low-speed side cam elevation 43B, the outer diameter of a base circle of the cam profile is the same and the base circle is located at the same circumferential position.

[0067] Each inlet-side cam carrier 43 has a guide groove cylinder area 43D located on the right side of the right high-speed-side cam lobe 43A, which is contained in the right set of high-speed-side cam lobe 43A and low-speed-side cam lobe 43B, wherein the guide groove cylinder area 43D has a guide groove 44 designed to extend in a circumferential direction (see Fig. 8 and Fig. 9).

[0068] The guide groove cylinder area 43D has a slightly smaller outside diameter than the outside diameters of the base circles of the high-speed side cam elevation 43A and the low-speed side cam elevation 43B, the base circles having the same diameter.

[0069] Four intake-side cam carriers 43 are wedged one after the other around the shaft keyway 42b of the intake-side camshaft 42 and are arranged at certain intervals on the intake-side camshaft 42.

[0070] The intake-side camshaft 42, on which four intake-side cam carriers 43 are arranged, is pivotably held by the support wall 3vr of the upper cylinder head 3U and the rear bearing 3vv of the four support walls 3v of the upper cylinder head 3U, as shown in Fig. 5 shown.

[0071] The held part 42a of the intake-side camshaft 42 is held by the support wall 3vr, and the held cylinder areas 43C of the intake-side cam carrier 43 are held by the respective support walls 3v.

[0072] On the other hand, as with the intake-side cam carriers 43, each of the exhaust-side cam carriers 53, which are keyed in around the shaft keyway 52b of the exhaust-side camshaft 52, has two pairs of high-speed side cam lobes 53A and low-speed side cam lobes 53B, which are formed around an outer circumferential surface of the exhaust-side cam carrier 53 and adjacent to each other in the axial lateral direction, and have different cam profiles, and a held cylinder area 53C, which is arranged between the pairs of cam lobes 53A and 53B in the lateral direction and has a certain width in the axial direction.Each exhaust-side cam carrier 53 has a guide groove cylinder area 53D located on the right side of the right high-speed side cam elevation 53A, which is contained in the right set of high-speed side cam elevation 53A and low-speed side cam elevation 53B.

[0073] A guide groove 54, which is formed in the guide groove cylinder area 53D, has a guide groove 54c of a stable state, which runs circumferentially around the exhaust-side cam carrier 53 and a right-displacement guide groove 54r and a left-displacement guide groove 541, which branch to the right and to the left from the guide groove of a stable state 54c and spirally extend to positions at certain distances from the guide groove 54c of a stable state in the axial lateral direction (see Fig. 5).

[0074] The exhaust-side camshaft 52 with four exhaust-side cam carriers 53, which are successively keyed in around the shaft keyway 52b, is held rotatably around the shaft by the support wall 3vr of the upper cylinder head 3U and the front bearings 3vv of the four support walls 3v of the upper cylinder head 3U, as shown in Fig. 5 shown.

[0075] The held part 52a of the exhaust-side camshaft 52 is held by the support wall 3vr, and the held cylinder areas 53C of the exhaust-side cam carrier 53 are held by the respective support walls 3v.

[0076] In a case where the intake camshaft 42 (and the intake cam carriers 43) and the exhaust camshaft 52 (and the exhaust cam carriers 53) are held by the support wall 3vr and the four support walls 3v of the upper cylinder head 3U as described above, the intake camshaft 42 (and the intake cam carriers 43) and the exhaust camshaft 52 (and the exhaust cam carriers 53) are arranged between them and are rotatably mounted between the camshaft supports 33 (see Fig. 4) held, each positioned on the support wall 3vr and the four support walls 3v.

[0077] That is, the four intake-side cam carriers 43 are rotatably mounted around the shaft so that they can be displaced in the axial direction while rotating with the intake-side camshaft 42. The four exhaust-side cam carriers 53 are rotatably mounted around the shaft so that they can be displaced in the axial direction while rotating with the exhaust-side camshaft 52.

[0078] The intake-side driven gear 49, which is attached to the right end of the intake-side camshaft 42, has the same diameter as the exhaust-side driven gear 59, which is attached to the right end of the exhaust-side camshaft 52. The intake-side driven gear 49 and the intake-side camshaft 42 are each arranged opposite each other in the timing chain chamber 3c, at a rear and a front. As shown in Fig. As shown in Figure 4, an idle gear 61, which has a larger diameter and engages with both the inlet-side drive gear 49 and the outlet-side drive gear 59, is held rotatably between and below the gears 49 and 59.

[0079] Power from the crankshaft 10, which is located below the idle gear 61, is transmitted to the idle gear 61 via a timing chain 66 or similar.

[0080] With reference to Fig. 6 is an intake-side switching drive shaft 71 of an intake-side cam switching mechanism 70 arranged obliquely in front of and below and parallel to the intake-side camshaft 42, and an exhaust-side switching drive shaft 81 of an exhaust-side cam switching mechanism 80 is arranged obliquely in front of and below and parallel to the exhaust-side camshaft 52.

[0081] The intake-side shift drive shaft 71 and the exhaust-side shift drive shaft 81 are held by the upper cylinder head 3U.

[0082] With reference to Fig. 5 and Fig. 6 is in the upper cylinder head 3U a laterally oriented tubular area 3A is formed in the valve chamber 3d at a position slightly behind the center of the valve chamber 3d and runs in a straight line from the support wall 3vr and passes through the four support walls 3v.

[0083] Similarly, in the upper cylinder head 3U, a laterally oriented tubular part 3B is formed in the valve chamber 3d opposite an inner surface of the front wall and runs in a straight line from the support wall 3vr and passes through the four support walls 3v (see Fig. 5).

[0084] The inlet-side switching drive shaft 71 is axially displaceable and fitted into the axial opening of the tubular part 3A, and the outlet-side switching drive shaft 81 is axially displaceable and inserted through a shaft opening in the tubular area 3B.

[0085] Two surfaces of the tubular areas 3A at opposite positions above the support wall 3v, where the surfaces correspond to the right and left intake valves 41 respectively, are machined away to expose the intake-side switching drive shaft 71. Intake rocker arm arms 72 are pivotally mounted on the exposed areas of the intake-side switching drive shaft 71 (see Fig. 5 and Fig. 6).

[0086] That is, the intake-side shift drive shaft 71 also serves as a rocker arm shaft.

[0087] With reference to Fig. 4 and Fig. 6 a peak area of ​​the inlet rocker arm 72 is located against an upper end area of ​​the inlet valve 41, and an axial movement of the inlet-side cam carrier 43 brings a high-speed-side cam elevation 43A or the low-speed-side cam elevation 43B into displaceable contact with a curved upper end surface of the inlet rocker arm 72.

[0088] Accordingly, a rotation of the intake-side cam carrier 43 causes a movement of the high-speed-side cam elevation 43A or the low-speed-side cam elevation 43B to oscillate the intake rocker arm 72 according to the profile of the cam elevation to push the intake valve 41, thereby opening an intake valve opening of the combustion chamber 30.

[0089] Similarly, two surfaces of the tubular areas 3B are clamped at opposite positions across the support wall 3v, with the surfaces corresponding to the right and left exhaust valves 51 respectively, in order to expose the exhaust-side switching drive shaft 81. Exhaust rocker arm arms 82 are pivotally mounted by the exposed areas of the exhaust-side switching drive shaft 81 (see Fig. 5 and Fig. 6).

[0090] That is, the exhaust-side shift drive shaft 81 also serves as a rocker arm shaft.

[0091] With reference to Fig. 4 and Fig. 6 a peak area of ​​the exhaust rocker arm 82 is located against an upper end area of ​​the exhaust valve 51, and a movement of the exhaust-side cam carrier 53 brings a high-speed-side cam elevation 53A or the low-speed-side cam elevation 53B into displaceable contact with a curved upper end surface of the exhaust rocker arm 82.

[0092] Accordingly, a rotation of the exhaust-side cam carrier 53 causes a movement of the high-speed-side cam elevation 53A or the low-speed-side cam elevation 53B to oscillate the intake rocker arm 82 according to the profile of the cam elevation to push the exhaust valve 51, thereby opening an exhaust valve opening of the combustion chamber 30.

[0093] With reference to Fig. 5 In a surface of the tubular area 3A, which corresponds to the guide groove cylinder area 43D of the inlet side cam carrier 43, two laterally adjacent cylindrical projection areas 3As are formed to protrude in the direction of the guide groove cylinder area 43D.

[0094] An internal opening in the cylindrical attachment area 3As passes through the tubular area 3A.

[0095] A first switching pin 73 and a second switching pin 74 are inserted and fitted so as to be slidable through the inner openings in the left and right cylindrical projection areas 3As.

[0096] With reference to Fig. 7 the first switching pin 73 has a tip-end cylinder area 73a and a base-end cylinder area 73b, which are connected to each other in a straight line by an intermediate connecting rod area 73c.

[0097] Furthermore, an engagement end region 73d, which has a smaller diameter compared to the tip-side cylinder region 73a, protrudes from the tip-side cylinder region 73a.

[0098] The intervention end region 73d has a flat tip surface 73df and an outer circumferential surface 73ds, which corresponds to an outer surface.

[0099] An end surface on the side of the intermediate connecting rod area 73c of the base end cylinder area 73b corresponds to a spherical end surface 73bf, which forms a spherical surface.

[0100] The second switching pin 74 has the same shape. A tip-end cylindrical section 74a and a base-end cylindrical section 74b are connected to each other in a straight line by an intermediate connecting rod section. An engagement end section 74d, which has a smaller diameter compared to the tip-end cylindrical section 74a, projects from the tip-end cylindrical section 74a.

[0101] On the other hand, as in Fig. As shown in Figure 7, the inlet-side shift drive shaft 71 has a slot 71a that passes through the center of the shaft.

[0102] The slot 71a has a slightly larger width than the diameter of the intermediate connecting rod area 73c of the first switching pin 73 and a smaller diameter than the base end cylinder area 73b.

[0103] One of the opening end surfaces of the slot 71a of the inlet-side switching drive shaft 71 is provided with a cam surface 71C in which two lateral flat surfaces 71Cp and a recessed curved surface 71Cv, which is recessed in a specific shape, has two lateral flat surfaces 71Cp and a recessed curved surface 71Cv.

[0104] The first switching pin 73 is attached to the intake-side switching drive shaft 71 in such a way that the intermediate connecting rod section 73c passes through the slot 71a of the intake-side switching drive shaft 71 and that the first switching pin 73 is biased by a coil spring 75 to press the spherical end surface 73bf of the base-end cylinder section 73b against the cam surface 71C, which corresponds to the open end surface of the slot 71a of the intake-side switching drive shaft 71.

[0105] Accordingly, a direct-acting cam mechanism Ca is provided in which an axial movement of the inlet-side switching drive shaft 71 causes contact with the cam surface 71C of the spherical end surface 73bf of the base-end cylinder region 73b of the first switching pin 73, which is in an axially fixed position and slides in a direction orthogonal to the axial direction, and wherein the spherical end surface 73bf is guided by the shape of the cam surface 71C to advance and retract the first switching pin 73 in a direction perpendicular to the axial direction.

[0106] As in Fig. As shown in Figure 7, the first switching pin 73 and the second switching pin 74 are arranged parallel to each other in order to pass through the common slot 71a of the inlet-side switching drive shaft 71.

[0107] It should be emphasized that a circular opening 71b, which penetrates the center of the shaft, is formed at the left end of the slot 71a.

[0108] The circular openings 71b have an inner diameter that is slightly larger than the outer diameter of the base end cylinder areas 73b and 74b and are used for an installation operation of the first switching pin 73 and the second switching pin 74.

[0109] Fig. Figure 7 illustrates that the center of the recessed curved surface 71Cv of the cam surface 71C of the intake-side drive shaft 71 is located at the position of the first switching pin 73. The first switching pin 73 is located in a position where it has been advanced after its spherical end surface 73bf comes to rest against the recessed curved surface 71Cv. The second switching pin 74 is located in a position where it has been retracted after its flat surface 71Cp comes to rest against the cam surface 71C.

[0110] In this state, in a case where the inlet-side shift drive shaft 71 moves to the left, the first shift pin 73 is reset, with the spherical end surface 73bf moving from the center of the recessed curved surface 71Cv up a right inclined surface of the recessed curved surface 71Cv and coming to rest against the right flat surface 71Cp, and the second shift pin 74 is advanced with the spherical end surface 74bf moving along the flat surface 71Cp and down a left inclined surface of the recessed curved surface 71Cv, and coming to rest against the center of the recessed curved surface 71Cv.

[0111] In this way, the axial movement of the inlet-side switching drive shaft 71 allows the first switching pin 73 and the second switching pin 74 to alternately extend and retract.

[0112] It should be emphasized that, although not shown, the tubular area 3B, in which the exhaust-side switching drive shaft 81 is axially displaceable and installed, is provided with two laterally adjacent cylindrical projection areas 3Bs through which a first switching pin 83 and a second switching pin 84 are displaceably inserted and installed, as is the case with the tubular area 3A, and that the first switching pin 83 and the second switching pin 84 are arranged parallel to each other in order to pass through a common slot 81a in the exhaust-side switching drive shaft 81 (see Fig. 5 and Fig. 6).

[0113] A direct acting cam mechanism Cb is provided in which the axial movement of the exhaust-side switching drive shaft 81 causes the first switching pin 83 and the second switching pin 84 to be advanced and retracted in a direction perpendicular to the axial direction by a cam surface of the slot 81a (the cam surface has the same shape as that of the cam surface 71C).

[0114] With reference to Fig. 5 and Fig. 6 the left side wall 3Lh of the upper cylinder head 3U is provided with an inlet-side hydraulic actuator 77, which protrudes into the valve chamber 3d and moves the inlet-side switching drive shaft 71 in the axial direction, and an outlet-side hydraulic actuator 87 is provided, which is installed in the valve chamber 3d in front of and opposite the inlet-side hydraulic actuator 77 and moves the outlet-side switching drive shaft 81 in the axial direction.

[0115] In the inlet-side hydraulic actuator 77, a bottom-mounted cylindrical inlet-side actuator drive 79 is fitted in an inner chamber of a housing with a circular opening in the inlet-side actuator housing 78 for a sliding back-and-forth movement in the axial direction (lateral direction) of the inlet-side switching drive shaft 71. The inlet-side switching drive shaft 71 is fitted into the inlet-side actuator drive 79 at the left end of the inlet-side switching drive shaft 71 in order to move integrally with the inlet-side hydraulic actuator 77.

[0116] Similarly, in the hydraulic actuator 87, a bottom-mounted, cylindrical, outlet-side actuator drive 89 is fitted on the outside in an inner chamber of the housing with a circular opening in the outlet-side actuator housing 88 for slidable back-and-forth movement in the lateral direction. The outlet-side switching drive shaft 81 is fitted into the outlet-side actuator drive 89 at the left end of the outlet-side switching drive shaft 81 in order to move integrally with the outlet-side hydraulic actuator 87.

[0117] A linear solenoid valve 91 is attached to a front mating surface at the left end of the front side wall 3Fr of the upper cylinder head 3U.

[0118] The linear solenoid valve 91 has a bushing 93 which is provided on an extension of an electromagnet 92 in which a piston moves through an electromagnetic coil.

[0119] The linear magnet 91 supplies pressurized oil to the inlet-side hydraulic actuator 77 and the outlet-side hydraulic actuator 87 through the bushing 93 in order to move the inlet-side switching drive shaft 71 and the outlet-side switching drive shaft 81 in the axial direction.

[0120] Fig. 8 and Fig. Figure 9 shows perspective views of different rotational states of the intake-side cam carrier 43 viewed in the same direction.

[0121] The guide groove 44, which is formed in the guide groove cylinder area 43D, is provided with a guide groove 44c of a stable state, which is located at an axially fixed position and extends around the guide groove cylinder area 43 in the circumferential direction, and a left-displacement guide groove 441 and a right-displacement guide groove 44r, which branch laterally from the guide groove 44c of a stable state and extend to a position at a certain distance from the guide groove 44c of a stable state in the axial lateral direction.

[0122] It should be emphasized that each of the displacement guide grooves 441 and 44r has a groove bottom surface G and groove side wall surfaces F1 and F2 on the opposite sides of the groove bottom surface G and is thus shaped like a channel.

[0123] In the present embodiment, the right-displacement guide groove 44r and the left-displacement guide groove 441 of the guide groove cylinder area 43D are each provided with a right-hand protective element 101 and a left-hand protective element 102, each corresponding to an elastic band-like element.

[0124] Fig. 12 is a development of the guide groove 44 (right-displacement guide groove 44r, guide groove 44c of a stable state and the left-displacement guide groove 441) in the guide groove cylinder area 43D and the protective elements 101 and 102.

[0125] With reference to Fig. 12 are formed on the groove sidewall surfaces F1, which are contained in the groove sidewall surfaces F1 and F2 of the right-displacement guide groove 44r and come into slidable contact with the first switching pin 73 and are thereby pressed, and the groove sidewall surfaces F1, which are contained in the groove sidewall surfaces F1 and F2 of the left-displacement guide groove 441 and are brought into slidable contact with the second switching pin 74 and are pressed away from it, slidable sidewall surfaces Faz are formed, wherein a displacement action is carried out on each of them and each of them runs from a displacement start tilting region Pa, at which the switching pin 73 or 74 causes the inlet-side cam carrier 43 to start displacing, through a displacement intermediate region Pb to a displacement end tilting region Pz, at which the displacement ends.

[0126] The displacement guide grooves 44r and 441 converge with the guide groove 44c of a stable state in the displacement end-tilt region Pz.

[0127] The right-hand protective element 101, which corresponds to a band-like elastic element provided in the right-displacement guide groove 44r, is generally designed as a circular arc along the right-displacement guide groove 44r, as shown in Fig. 8 and Fig. 9 shown.

[0128] Fig. Figure 10 is a perspective view of the right protective element 101, and Fig. Figure 11 is a cross-sectional view of the right protective element 101 in one direction of an arrow XI in Fig. 10 considered.

[0129] With reference to Fig. 10 and Fig. 8 and Fig. 9 is a hook area 101h, which protrudes from a point on the right protective element 101, which is slightly forward in the direction of rotation from the center of the circular arc of the right protective element 101, on a groove side wall area W2, which has the groove side wall surface F2, hooked by one of the groove side wall surfaces of the right-displacement guide groove 44r, so that the hook area 101h spreads outwards and holds the groove side wall area W2.

[0130] It should be emphasized that an outer circumferential surface of a hook receiving area wk of the groove side wall area W2, on which the hook area 101h of the right protective element 101 is hooked, is completely flat, and a groove side wall surface of the groove side wall area W2 opposite the groove side wall surface F2 is grooved to prevent the hooked hook area 101h from protruding from the outer circumferential surface and the groove side wall surface of the groove side wall area W2.

[0131] The right-hand protective element 101 has a fixed side part 101a, which is located on the forward side with respect to the hook area 101h and is fitted and fastened in the right-displacement guide groove 44r and extends in a circular arc or a similar shape, while it has a switching pin entry inhibition part 101b, which is located on the retraction side with respect to the hook area 101h and corresponds to a non-fixed free side area and extends in a circular arc or a similar shape.

[0132] The fixed side part 101a and the switching pin entry inhibition part 101b are arranged continuously and both are provided in the right-shifting guide groove 44r.

[0133] The fixed side part 101a of the right protective element 101 extends from the hook area 101h to the projection side in contact with the groove side wall surface F2, and a curved base end area 101ae of the fixed side part 101a is bent along an inner end surface of the curved projection side of the right-displacement guide groove 44r.

[0134] The switching pin entry inhibiting part 101b of the right guard element 101 extends from a region of the right guard element 101 that is near the hook region 101h and in contact with the groove side wall surface F2 to the extension side in such a way as to slowly leave the groove side wall surface F2 while approaching the other groove side wall surface F1, with a rear end region 101be of the free side of the switching pin entry inhibiting part 101b being in contact with or near the groove side wall surface F1.

[0135] An inner circumferential edge of the switching pin entry inhibition part 101b of the right-hand guard element 101, wherein the area is bent in a circular arc or in a similar shape, is located away from the groove bottom surface G of the right-displacement guide groove 44r. The switching pin entry inhibition part 101b has protruding areas 101bp located at a rear end area 101be and an intermediate area of ​​the switching pin entry inhibition part 101b and in contact with the groove bottom surface G.

[0136] It should be emphasized that the area surrounding the hook region 101h of the right protective element 101 is linearly formed in accordance with the hook receiving area wk of the groove side wall area W2, wherein the outer circumferential surface of the hook receiving area wk is completely flat and a linearly formed part of the inner circumferential edge of the right protective element 101 is in contact with the groove bottom surface G.

[0137] The fixed side part 101a and the switching pin entry suppression part 101b of the right protective element 101 are each shaped like a circular arc corresponding to about three-quarters of the circumference and are inserted into the displacement guide groove 44r in such a way as to engage a circumferential surface of the groove bottom surface G of the right displacement guide groove 44r.

[0138] The outer circumferential edge of the switching pin entry suppression part 101b, which is bent in a circular arc or similar shape, is located on the same circumferential surface as the outer circumferential surface of the guide groove cylinder area 43D.

[0139] As in Fig. Figure 12 shows the hook area 101h of the right-hand protective element 101 attached to the groove sidewall area W2 at a circumferential position substantially between the displacement start tilting region Pa of the groove sidewall surface F1 and the inner end region of the projecting side of the right-displacement guide groove 44r, and the switching pin entry inhibiting part 101b, which is located on the reset side with respect to the hook area 101h in the direction of rotation, extends from the groove sidewall surface F2 at a certain circumferential position Yaa slightly projecting from the displacement start tilting region Pa as it approaches the groove sidewall surface F1, and reaches a displacement intermediate region Pb which corresponds to an intermediate region of the displaceable sidewall surface Faz, where the switching pin entry inhibiting part 101b is in contact with or near the groove sidewall surface F1.

[0140] With reference to Fig. In the right-displacement guide groove 44r, a specific circumferential region Zab is located at the specified circumferential position Yaa, slightly forward of the displacement-start tilting region Pa. This circumferential region may exhibit an event in which, for example, when the first switching pin 73 is in action to enter the right-displacement guide groove 44r, the groove side wall surface F1 of the right-displacement guide groove 44r comes into conflict with and contact with the tip of the first switching pin 73, which is then tilted. The specified circumferential region Zab is therefore unsuitable for the entry of the first switching pin 73.

[0141] The switching pin entry inhibition part 101b of the right-hand protective element 101 is arranged to traverse the right-displacement guide groove 44r obliquely from the groove side wall surface F2 to the groove side wall surface F1 in the defined circumferential region Zab. Thus, the first switching pin 73, which is active to enter the right-displacement guide groove 44r in the defined circumferential region Zab, comes to rest against the outer circumferential edge of the switching pin entry inhibition part 101b at the tip surface 73df of the engagement end region 73d of the first switching pin 73.

[0142] Accordingly, the occurrence of an event can be avoided in which, for example, the first switching pin 73 is tilted through the groove side wall surface F1.

[0143] Upon entering the right-displacement guide groove 44r at a circumference other than the defined circumference Zab of the right-hand protective element 101, the first switching pin 73 can engage seamlessly in the right-displacement guide groove 44r. In a case where the engaged first switching pin 73 reaches the defined circumference Zab of the rotating right-displacement guide groove 44r, the outer circumferential surface 73ds of the engagement end region 73d of the first switching pin 73 comes into contact with the switching pin entry obstruction part 101b of the right-hand protective element 101, which is located in the defined circumference Zab, thus blocking a path in the right-displacement guide groove 44r. As shown in Fig. As shown in Figure 13, the outer circumferential surface 73ds presses the switching pin entry inhibiting part 101b and elastically shapes it to press the switching pin entry inhibiting part 101b against the guide groove wall surface F2, thereby clearing the path in the right-shift guide groove 44r. This allows the first switching pin 73 to be engaged in the right-shift guide groove 44r, enabling the intake-side cam carrier 43 to be shifted to the right.

[0144] As soon as the first switching pin 73 passes through the defined circumferential area Zab, the switching pin entry inhibiting part 101b of the right protective element 101, which corresponds to an elastic element, returns to its original position, where the switching pin entry inhibiting part 101b blocks the path in the right-displacement guide groove 44r. The first switching pin 73 is displaced from the right-displacement guide groove 44r to the guide groove 44c of a stable state.

[0145] As described above, the right-shift guide groove 44r of the inlet-side cam carrier 43 is provided with the right-hand protective element 101, which prevents the first switching pin 73 from entering the specific circumferential area Zab, which is unsuitable for the entry of the first switching pin 73. This prevents the first switching pin 73 from being flicked away from the groove side wall surface F1 of the right-shift guide groove 44r, and the first switching pin 73 engages seamlessly in the right-shift guide groove 44r, thus improving the operational reliability of the cam circuit.

[0146] The other left-hand guard element 102 has a fixed side part 102a, a switching pin entry suppression part 102b, and a hook area 102h. The left-hand guard element 102 and the right-hand guard element 101 are laterally symmetrical in shape, and the left-hand guard element 102 is provided in the left-displacement guide groove 441, so that the left-hand guard element 102 and the right-hand guard element 101 are essentially laterally symmetrical. Thus, the left-hand guard element 102 acts in a similar manner to the right-hand guard element 101 described above and produces the same effects as those of the right-hand guard element 101.

[0147] A second embodiment based on the following is described. Fig. Described in sections 14 to 19.

[0148] The shape of the cam carriers in the second embodiment is the same as the shape of the cam carriers 43 and 53 in the first embodiment, with the exception of a certain part of the shape, and is described by means of the same reference numerals.

[0149] In particular, the intake-side cam carrier 43 is described with reference to Fig. Described in sections 14 to 17. However, the description also applies to the exhaust-side cam carrier 53, which is not shown.

[0150] In the inlet-side cam carrier 43 in the second embodiment, the shape of each guide groove 44 is the same as the shape of the guide groove 44 in the first embodiment: the guide groove 44 has the guide groove 44c of a stable state, which is located at the axially fixed position in the guide groove cylinder area 43D and extends around the guide groove cylinder area 43D in the circumferential direction, and the left-displacement guide groove 441 and the right-displacement guide groove 44r branch off laterally from the guide groove 44c of a stable state.

[0151] In the second embodiment, a right protective element 201 and a left protective element 202, each corresponding to an elastic, generally arc-shaped steel wire element, are provided for the right-displacement guide groove 44r and the left-displacement guide groove 441 of the guide groove cylinder area 43D, respectively.

[0152] With reference to a development of the guide groove 44 of the guide groove cylinder area 43D and the protective elements 201 and 202 in Fig. 18 In the outer circumferential surface of the groove sidewall region W1, which has the groove sidewall surface F1, which partially has the displaceable sidewall surface Faz, which runs from the displacement start tilting region Pa of the guide groove cylinder region 43D through the displacement intermediate region Pb to the displacement end tilting region Pz, where the displacement is terminated, a shallow circumferential groove 45v is formed to run in the circumferential direction; the circumferential groove 45v has an axial width of the protective element 201 or 202 between a region axially outside of the displacement start tilting region (Pa) through a width of the protective element (201, 202) and the displacement intermediate region Pb and has a groove depth equal to a radial thickness of the protective element 201 or 202.

[0153] The circumferential groove 45v has a wide circumferential groove part 45vw, which is located axially inwards from the displacement start tilting region Pa, which corresponds to the displaceable side wall surface Faz, and a narrow circumferential groove part 45vn, which is located axially outside the displacement start tilting region Pa, which has a width equal to the width of the protective element 201 or 202.

[0154] The circumferential grooves 45v are symmetrically formed according to the right-shift guide groove 44r and the left-shift guide groove 441.

[0155] The wide circumferential groove section 45vw is formed between the movable side wall surface Faz and each of the inner end regions 44re and 44le of the right-hand displacement guide groove 44r and the left-hand displacement guide groove 441 on the advance side in the direction of rotation of the intake-side cam carrier 43. The narrow circumferential groove section 45vn, which is located axially outside the wide circumferential groove section 45vw, is formed completely around the intake-side cam carrier 43 by cutting out a side edge of the groove side wall region W1.

[0156] In the narrow circumferential groove section 45vn, hook receiving openings 45vh are formed at a position on the advance side with respect to each of the inner end regions 44re and 44le of the right-shift guide groove 44r and the left-shift guide groove 441 on the advance side in the direction of rotation of the inlet-side cam carrier 43.

[0157] The right protective element 201 and the left protective element 202, which correspond to elastic steel wire elements, each have switching pin entry inhibition parts 201b and 202b, which extend continuously from fixed side parts 201a and 202a, and extension parts 201c and 202c, which continue continuously from the switching pin entry inhibition parts 201b and 202b.

[0158] A base end region 201ae of the fixed side part 201a of the right protective element 201 is bent and inserted and hooked into the hook receiving opening 45vh in the narrow circumferential groove part 45vn on the outside of the circumferential groove 45v, and runs in the direction of the retraction side opposite the advance side in the direction of rotation of the inlet-side cam carrier 43 and is inserted and fastened in the narrow circumferential groove part 45vn on the outside of the circumferential groove 45v.

[0159] With reference to Fig. 18 The switching pin entry suppression part 201b of the right protective element 201 has a base region 201ba that extends continuously with the fixed side part 201a and is in contact with the groove side wall surface F1 in the specific circumferential position Yaa, slightly forward of the displacement start tilt region Pa. The switching pin entry suppression part 201b slowly leaves the groove side wall surface F1 at the base region 201ba and extends towards the retraction side opposite the advancement side in the direction of rotation of the inlet-side cam carrier 43, while approaching the curved groove side wall surface F1 (displaceable side surface Faz). A rear region 201be, which extends continuously to the extension part 201c, contacts the displacement intermediate region Pb of the displaceable side wall surface Faz.

[0160] Accordingly, the switching pin entry inhibition part 201b of the right protective element 201 is inserted in the right-displacement guide groove 44r in a certain circumferential area Zab, which corresponds to a circumferential area that is unsuitable for the entry of the first switching pin 73.

[0161] The extension part 201, which extends continuously from the rear area 201be of the switching pin entry suppression part 201b of the right protective element 201, is inserted in the wide circumferential groove part 45vw of the circumferential groove 45v of the groove side wall area W1 and slidably contacts a groove side wall 45vf of the wide circumferential groove part 45vw opposite the narrow circumferential groove part 45vn.

[0162] The fixed side part 201a and the extension part 201c on the opposite sides of the switching pin entry suppression part 201b of the right-hand protective element 201 are inserted and fitted into the circumferential groove 45v formed in the outer circumferential surface of the groove side wall region W1 and have a groove depth that is essentially equal to the radial thickness of the protective element 201. Thus, the switching pin entry suppression part 201b, which is inserted in the right-hand displacement guide groove 44r, is arranged along a groove opening of the right-hand displacement guide groove 44r.

[0163] The switching pin entry inhibiting part 201b of the right-hand protective element 201 is inserted into the right-displacement guide groove 44r along the groove opening in a specific circumferential region Zab, which is unsuitable for the entry of the first switching pin 73. Thus, in a case where the first switching pin 73 is active to enter the right-displacement guide groove 44r in the specific circumferential region Zab, the tip surface 73df of the engagement end region 73d of the first switching pin 73 comes into contact with the outer circumferential edge of the switching pin entry inhibiting part 201b to prevent the first switching pin 73 from entering the right-displacement guide groove 44r.

[0164] Accordingly, an event can be avoided in which, for example, the first switching pin 73 is tilted through the groove side wall surface F1.

[0165] Upon entering the right-displacement guide groove 44r at a circumference other than the defined circumference Zab of the right-hand protective element 201, the first switching pin 73 can engage seamlessly in the right-displacement guide groove 44r. If the engaged first switching pin 73 reaches the defined circumference Zab of the rotating right-displacement guide groove 44r, the outer circumferential surface 73ds of the engagement end region 73d of the first switching pin 73 comes into contact with the switching pin entry obstruction part 201b of the right-hand protective element 201, which is located in the defined circumference Zab, thus blocking the path in the right-displacement guide groove 44r. Fig. As shown in Figure 19, the outer circumferential surface 73ds presses the switching pin entry inhibiting part 201b and deforms it elastically to insert the switching pin entry inhibiting part 201b into the circumferential groove 45v in such a way as to press the switching pin entry inhibiting part 201b against the groove side wall surface F1, thereby clearing the path in the right-shift guide groove 44r. This allows a state to be maintained in which the first switching pin 73 is engaged in the right-shift guide groove 44r, which enables the intake-side cam carrier 43 to be shifted to the right.

[0166] As soon as the first switching pin 73 passes through the defined circumferential area Zab, the switching pin entry inhibiting part 201b of the right protective element 201, which corresponds to an elastic element, returns to its original position, where the switching pin entry inhibiting part 201b is inserted in the path in the right-displacement guide groove 44r. The first switching pin 73 is displaced from the right-displacement guide groove 44r to the guide groove 44c of a stable state.

[0167] As described above, the right-shift guide groove 44r of the inlet-side cam carrier 43 is provided with the right-hand protective element 201, which prevents the first switching pin 73 from entering the specific circumferential area Zab, which is unsuitable for the entry of the first switching pin 73. This prevents the first switching pin 73 from being flicked away by the groove side wall surface F1 of the right-shift guide groove 44r, and the first switching pin 73 engages seamlessly in the right-shift guide groove 44r, thus improving the operational reliability of the cam circuit.

[0168] The other left protective element 202 and the right protective element 201 are laterally symmetrical in shape, and the left protective element 202 is provided in the left-displacement guide groove 441 such that the left protective element 202 and the right protective element 201 are essentially laterally symmetrical. Thus, the left protective element 202 acts in a similar manner to the right protective element 201 described above and produces the same effects as those of the right protective element 201.

[0169] The following describes a third embodiment based on Fig. Described in sections 20 to 26.

[0170] The shape of the cam carriers in the third embodiment is the same as the shape of the cam carriers 43 and 53 in the first embodiment, except for a certain part of the shape, and is described using the same reference numerals.

[0171] In particular, the intake-side cam carrier 43 is described with reference to Fig. Described in sections 20 to 23. However, the description also applies to the exhaust-side cam carrier 53, which is not shown.

[0172] In the inlet-side cam carrier 43 in the third embodiment, the shape of each guide groove 44 is the same as the shape of the guide groove 44 in the first embodiment: the guide groove 44 has the guide groove 44c of a stable state, which is located at the axially fixed position in the guide groove-cylinder area 43D and extends around the guide groove-cylinder area 43D in the circumferential direction, and the left-displacement guide groove 441 and the right-displacement guide groove 44r branch off laterally from the guide groove 44c of a stable state.

[0173] In the present third embodiment, a right protective element 301 and a left protective element 302, each corresponding to an elastic generally arc-shaped steel wire element, are provided for the right-displacement guide groove 44r and the left-displacement guide groove 441 of the guide groove cylinder area 43D, respectively.

[0174] With reference to a development of the guide groove 44 of the guide groove cylinder area 43D and the protective elements 301 and 302, insertion grooves 46 are formed in the groove side wall area W2, through which the protective elements 301 and 302 are inserted and fitted. The groove side wall area W2 has the groove side wall surface F2 opposite the groove side wall surface F1, which partially has the displaceable side wall surface Faz, which runs from the displacement start tilting area Pa of the guide groove cylinder area 43D through the displacement intermediate area Pb to the displacement end tilting area Pz, where the displacement is terminated.

[0175] The insertion groove 46 has an inner circumferential groove line 46i, which is formed circumferentially in an inner circumferential surface of the guide groove cylinder area 43D, which has internal wedge teeth and groove openings 46j, which are formed by cutting out a part of the groove side wall area W2 down to the inner circumferential surface, wherein the groove openings 46j penetrate the groove side wall surface W2 from the outside to the inside in order to be in exchange with the inner circumferential groove line 46i.

[0176] With reference to Fig. 22 each of the groove openings 46j corresponds to a part of the side of the groove side wall surface F2 of the groove side wall area W2 and is formed by cutting out a circumferential part which extends from the specific circumferential position Yaa from the displacement start tilting area Pa in the direction of rotation slightly forward to a specific circumferential position which is forward of the specific circumferential position Yaa in the direction of rotation and further cuts out the associated part inwards.

[0177] Accordingly, the groove openings 46j are open towards the side of the sliding guide groove 44r and 441.

[0178] The right protective element 301 and the left protective element 302, which correspond to elastic steel wire elements, each have switching pin entry inhibition parts 301b and 302b, which each extend continuously from fixed side parts 301a and 302a.

[0179] The fixed side part 301a of the right protective element 301 is fitted into the inner circumferential groove 46i of the insertion groove 46, which is formed in the inner circumferential surface of the guide groove cylinder area 43D. A base end area 301ae on the projection side of the fixed side part 301a is bent in the direction of rotation and hooked and fastened to the outer splined tooth of the intake-side camshaft 42 (see Fig. 21).

[0180] The fixed side part 301a passes through the inner circumferential groove line 46i in the inner circumferential surface of the guide groove cylinder area 43D and outside of the groove opening 46j, which is open in the outer circumferential surface.

[0181] The switching pin entry suppression part 301b, which extends continuously from the fixed side part 301a, has a base area 301ba that extends continuously from the fixed side part 301a and is in contact with the outer circumferential edge of the groove side wall surface F2 of the groove side wall area W2 at the specified circumferential position Yaa. From the base area 301ba at the specified circumferential position Yaa, the switching pin entry suppression part 301b extends towards the retraction side opposite the advance side in the direction of rotation of the inlet-side cam carrier 43 along a groove opening of the right-shift guide groove 44r, which is located on the outer circumferential surface of the guide groove cylinder area 43D, such that the switching pin entry suppression part 301b approaches the other groove side wall surface F1 in the right-shift guide groove 44r.A rear area 301be of the switching pin entry suppression part 301b is bent and is in contact with the groove side wall surface F1 at the displacement intermediate area Pb, and a bent tip of the rear area 301be is in contact with the groove bottom surface G of the right-displacement guide groove 44r.

[0182] Accordingly, the switching pin entry inhibiting part 301b of the right-hand protective element 301 is arranged in the right-hand displacement guide groove 44r along the groove opening in order to traverse the right-hand displacement guide groove 44r obliquely from the groove side wall surface F2 to the groove side wall surface F1 in the specific circumferential region Zab, which is unsuitable for the entry of the first switching pin 73 into the right-hand displacement guide groove 44r. Thus, the first switching pin 73, which is active for entering the right-hand displacement guide groove 44r in the specific circumferential region Zab, comes to rest against the outer circumferential edge of the switching pin entry inhibiting part 301b at the tip surface 73df of the engagement end region 73d of the first switching pin 73.

[0183] Accordingly, the occurrence of an event can be avoided in which, for example, the first switching pin 73 is tilted through the groove side wall surface F1.

[0184] Upon entering the right-displacement guide groove 44r at a circumference other than the defined circumference Zab of the right-hand protective element 301, the first switching pin 73 can engage seamlessly in the right-displacement guide groove 44r. If the engaged first switching pin 73 reaches the defined circumference Zab of the rotating right-displacement guide groove 44r, the outer circumferential surface 73ds of the engagement end region 73d of the first switching pin 73 comes into contact with the switching pin entry obstruction part 301b of the right-hand protective element 301, which is located in the defined circumference Zab, thus blocking the path in the right-displacement guide groove 44r. Fig. As shown in Figure 23, the outer circumferential surface 73ds presses the switching pin entry inhibiting part 301b and deforms it elastically in such a way as to press the switching pin entry inhibiting part 301b against the groove side wall surface F2, thereby clearing the path in the right-shift guide groove 44r. This allows a state to be maintained in which the first switching pin 73 is engaged in the right-shift guide groove 44r, which enables the intake-side cam carrier 43 to be shifted to the right.

[0185] As soon as the first switching pin 73 passes through the defined circumferential area Zab, the switching pin entry inhibiting part 301b of the right protective element 301, which corresponds to an elastic element, returns to its original position, where the switching pin entry inhibiting part 301b blocks the path in the right-displacement guide groove 44r. The first switching pin 73 is displaced from the right-displacement guide groove 44r to the guide groove 44c of a stable state.

[0186] As described above, the right-shift guide groove 44r of the inlet-side cam carrier 43 is provided with the right-hand protective element 301, which prevents the first switching pin 73 from entering the specific circumferential area Zab, which is unsuitable for the entry of the first switching pin 73. This prevents the first switching pin 73 from being flicked away by the groove side wall surface F1 of the right-shift guide groove 44r, and the first switching pin 73 engages seamlessly in the right-shift guide groove 44r, thus improving the operational reliability of the cam circuit.

[0187] The other left protective element 302 and the right protective element 301 are laterally symmetrical in shape, and the left protective element 302 is provided in the left-displacement guide groove 441, so that the left protective element 302 and the right protective element 301 are essentially laterally symmetrical. Thus, the left protective element 302 acts in a similar manner to the right protective element 301 described above and produces the same effects as those of the right protective element 301.

[0188] A modified example of the third embodiment is now presented in Fig. Figures 24 to 26 are shown.

[0189] In the present modified example, in the groove side wall area W2, which has the groove side wall surface F2 opposite the groove side wall surface F1, which partially has the movable side wall surface Faz of the guide groove cylinder area 43D, a fitting insertion groove 47 is formed by cutting out a part on the groove side wall surface F2 of the groove side wall area W2.

[0190] With reference to Fig. 26 a recess-side end region of the fitting insertion groove 47 is located opposite the advance side in the direction of rotation at the specified circumferential position Yaa, which is slightly forward of the displacement start tilting region Pa in the direction of rotation and runs from the specified circumferential position Yaa to the advance side, and an advance-side end region of the fitting insertion groove 47 is located at a position that is slightly forward of an advance-side end region from each of the displacement guide grooves 44r and 441.

[0191] The groove base surface of the fitting insertion groove 47 is located on the same circumferential surface as the groove base surface G of each of the sliding guide grooves 44r and 441.

[0192] A hook receiving opening 47h is formed on the extension side end area of ​​the fitting insertion groove 47, which is located on the extension side in the direction of rotation.

[0193] A right protective element 351 and a left protective element 352, corresponding to elastic steel wire elements, are laterally symmetrical and each have switching pin entry inhibition parts 351b and 352b, which each extend continuously from fixed side parts 351a and 352a.

[0194] The right-hand protective element 351 is described. The fixed side part 351a is inserted into the fitting insertion groove 47, which is formed in the groove side wall area W2, and a base end area 351ae of the fixed side part 351a, which is located on the projection side in the direction of rotation, is bent and hooked and secured in the hook receiving opening 47h (see Fig. 25).

[0195] The switching pin entry suppression part 351b, which extends continuously from the fixed side part 351a, has a base area 351ba that extends continuously from the fixed side part 351a and is in contact with the outer circumferential edge of the groove side wall surface F2 of the groove side wall area W2 at the specified circumferential position Yaa. From the base area 351ba at the specified circumferential position Yaa, the switching pin entry suppression part 351b extends towards the retraction side opposite the advance side in the direction of rotation of the inlet-side cam carrier 43 along the groove opening of the right-shift guide groove 44r, which is located on the outer circumferential surface of the guide groove cylinder area 43D, such that the switching pin entry suppression part 351b approaches the other groove side wall surface F1 in the right-shift guide groove 44r.A rear area 351be of the switching pin entry suppression part 351b is bent and is in contact with the groove side wall surface F1 at the displacement intermediate area Pb, and a bent tip of the rear area 351be is in contact with the groove bottom surface G of the right-displacement guide groove 44r.

[0196] Accordingly, as with the switching pin entry inhibiting part 301b, the switching pin entry inhibiting part 351b of the right-hand protective element 351 is arranged in the right-hand displacement guide groove 44r along the groove opening in order to traverse the right-hand displacement guide groove 44r obliquely from the groove side wall surface F2 to the groove side wall surface F1 in the specific circumferential region Zab, which is unsuitable for the entry of the first switching pin 73 into the right-hand displacement guide groove 44r. Thus, the first switching pin 73, which is active for entering the right-hand displacement guide groove 44r in the specific circumferential region Zab, comes to rest against the outer circumferential edge of the switching pin entry inhibiting part 351b at the tip surface 73df of the engagement end region 73d of the first switching pin 73.

[0197] Accordingly, the occurrence of an event can be avoided in which, for example, the first switching pin 73 is tilted through the groove side wall surface F1.

[0198] Upon entering the right-displacement guide groove 44r at a circumference other than the defined circumference Zab of the right-hand protective element 351, the first switching pin 73 can engage seamlessly in the right-displacement guide groove 44r. If the engaged first switching pin 73 reaches the defined circumference Zab of the rotating right-displacement guide groove 44r, the outer circumferential surface 73ds of the engagement end region 73d of the first switching pin 73 comes into contact with the switching pin entry obstruction part 351b of the right-hand protective element 351, which is located in the defined circumference Zab, thus blocking the path in the right-displacement guide groove 44r.The outer circumferential surface 73ds presses the switching pin entry inhibiting part 351b and deforms it elastically in such a way as to press the switching pin entry inhibiting part 351b against the groove side wall surface F2, thereby clearing the path in the right-shift guide groove 44r. This allows a state to be maintained in which the first switching pin 73 is engaged in the right-shift guide groove 44r, which enables the intake-side cam carrier 43 to be shifted to the right.

[0199] As soon as the first switching pin 73 passes through the defined circumferential area Zab, the switching pin entry inhibiting part 351b of the right protective element 351, which corresponds to an elastic element, returns to its original position, where the switching pin entry inhibiting part 351b blocks the path in the right-displacement guide groove 44r. The first switching pin 73 is displaced from the right-displacement guide groove 44r to the guide groove 44c of a stable state.

[0200] Thus, the left protective element 352 acts in a similar way to the right protective element 351 and produces the same effects as those of the right protective element 351.

[0201] The variable valve devices according to the three embodiments of the present invention have been described. The aspects of the present invention are not limited to the embodiments described above and may include various other aspects without departing from the spirit of the present invention. List of reference symbols:

[0202] Pu ··· Drive unit, E ··· Internal combustion engine, M ··· Transmission, 1 ··· Crankcase, 2 ··· Cylinder block, 3 ··· Cylinder head, 3L ··· Lower cylinder head, 3U ··· Upper cylinder head, 3Lh ··· Left side wall, 3v ··· Mounting wall, 3c ··· Timing chain chamber, 4 ··· Cylinder head cover, 5 ··· Oil pan, 7 ··· Threaded bolts, 10 ··· Crankshaft, 11 ··· Main shaft, 12 ··· Countershaft, 30 ··· Combustion chamber, 33 ··· Camshaft bracket, 40 ··· Variable valve assembly, 41 ··· Intake valve, 42 ··· Intake camshaft, 43 ··· Intake cam carrier, 43A ··· High-speed cam lift, 43B ··· Low-speed cam lift, 43D ··· Guide groove cylinder area, 44 ··· Guide groove, 44c ··· Stable-state guide groove, 441 ··· Left-shift guide groove, 44r ··· Right-shift guide groove, 45v ··· Circumferential groove, 45vw ··· Wide circumferential guide groove, 45vn ··· Narrow circumferential guide groove, 46 ··· Fit insert groove, 46i ··· Inner circumferential guide groove, 46j ··· Groove opening, 47 ··· Insert slot, 49 ··· Inlet-side driven gear, 51 Exhaust valve, 52 Exhaust camshaft, 53 Exhaust cam carrier, 53A High-speed cam lift, 53B Low-speed cam lift, 53D Guide groove cylinder area, 54 Guide groove, 54c Stable-state guide groove, 541 Left-shift guide groove, 54r Right-shift guide groove, 59 Exhaust-side driven gear 61 ··· Idler gear, 62 ··· Idler sprocket, 66 ··· Timing chain, 70 ··· Intake-side cam switching mechanism, 71 ··· Intake-side switching drive shaft, Ca ··· Direct-acting cam mechanism, 72 ··· Intake rocker arm, 73 ··· First switching pin, 73a ··· Tip-side cylinder area, 73b ··· Base-end cylinder area, 73bf ··· Spherical end face, 73c ··· Intermediate coupling rod area, 73d ··· Engagement end area, 73df ··· Tip surface, 73ds ··· Outer circumferential surface, 74 ··· Second switching pin, 75 ··· Coil spring, 77 ··· Intake-side hydraulic actuator, 79 ··· Intake-side actuator drive, 80 ··· Exhaust-side cam switching mechanism, 81 ··· Exhaust-side switching drive shaft, Cb ··· Cam mechanism, 82 ··· Exhaust rocker arm, 83 ··· First switching pin, 84 ··· Second switching pin, 87 ··· Exhaust-side hydraulic actuator, 89 ··· Exhaust-side actuator drive, 91 ··· Linear solenoid valve, 92 ··· Electromagnet, 93 ··· Bushing, 101 ··· Right guard element, 101a ··· Fixed side panel, 101ae ··· Curved base end section, 101h ··· Hook section, 101b ··· Switch pin entry inhibition section, 101ba ··· Base section, 101be ··· Rear end section, 101bp, 101bq ··· Protruding section, 102 ··· Left guard element, 102a ··· Fixed side panel, 102b ··· Switch pin entry inhibition part, 102h ··· Hook area, 102ba ··· Base area, 102be ··· Rear end area, 201 ··· Right guard element, 201a ··· Fixed side panel, 201ae ··· Base end section, 201b ··· Switch pin entry blocking section, 201ba ··· Base section, 201be ··· Rear section, 201c ··· Extension section, 202 ··· Left guard element, 202a ··· Fixed side panel, 202ae ··· Base end section, 202b ··· Switch pin entry blocking section, 202ba ··· Base section, 202be ··· Rear section, 202c ··· Extension section, 301 ··· Right guard element, 301a ··· Fixed side panel, 301ae ··· Base end area, 301b ··· Switch pin entry blocking part, 301ba ··· Base area, 301be ··· Rear area, 302 ··· Left guard element, 302a ··· Fixed side panel, 302b ··· Switch pin entry blocking part, 302ba ··· Base area, 302be ··· Rear end area, 351 ··· Right guard element, 351a ··· Fixed side panel, 351ae ··· Base end area, 351b ··· Switch pin entry blocking part, 352 ··· Left protective element, 352a ··· Fixed side panel, 352ae ··· Base end area, 352b ··· Switch pin entry inhibition part, 500 ··· Motorcycle, 502 ··· Head tube, 503 ··· Main frame, 504 ··· Seat rail, 505 ··· Front fork, 506 ··· Front wheel, 507 ··· Pivot shaft, 508 ··· Swingarm, 509 ··· Rear wheel, 510 ··· Linkage mechanism, 511 ··· Rear shock absorber, 512 ··· Drive sprocket, 513 ··· Drive sprocket, 514 ··· Drive chain, 516 ··· Fuel tank, 517 ··· Main seat, 518 ··· Passenger seat, 521 ··· Throttle valve, 522 ··· Air filter, 525 ··· Exhaust pipe.

Claims

[1] Variable valve device (40) comprising: a camshaft (42, 52) rotatably provided in a cylinder head (3) of an internal combustion engine (E); a cam carrier (43, 53) comprising a cylindrical member axially slidably fitted around an outer circumference of the camshaft (42, 52) while the rotation thereof relative to the camshaft (42, 52) is restricted, wherein the cam carrier (43, 53) has a plurality of cam lobes (43A, 43B, 53A, 53B) formed on an outer peripheral surface of the cam carrier (43, 53) and adjacent to each other in an axial direction and having different cam profiles, wherein the cam carrier (43, 53) is integrated with a guide groove cylindrical portion (43D, 53D) provided with a guide groove (44, 54) defined like a channel by a groove bottom surface (G) and groove side wall surfaces (F1, F2) on opposite sides of the groove bottom surface (G); and a cam switching mechanism (70, 80) which advances and retracts a switching pin (73, 74, 83, 84) so ​​that the switching pin (73, 74, 83, 84) is able to engage and disengage from the guide groove (44, 54), wherein the cam carrier (43, 53) is guided and displaced in the axial direction during rotation through the guide groove (44, 54) with the advanced switching pin (73, 74, 83, 84) engaged therein in order to switch the cam lobe (43A, 43B, 53A, 53B) acting on a valve (41, 51), wherein a second groove side wall surface (F1) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), which groove side wall surface (F1) is brought into sliding contact with the switching pin (73, 74, 83, 84) and is pressed thereby to slide the cam carrier (43, 53), has a sliding side wall surface (Faz) which extends from a sliding start inclination region (Pa) at which the cam carrier (43) starts to slide, through a sliding intermediate region (Pb) to a sliding end inclination region (Pz) at which the cam carrier (43) stops the sliding, and the cam carrier (43, 53) is provided with a protective element (101, 102) which prevents the entry of the switching pin (73, 74, 83, 84) into the guide groove (44, 54) in a certain circumferential area (Zab) from a certain circumferential position (Yaa) in a rotation direction of the cam carrier (43, 53) slightly offset forward from the shift start inclination area (Pa) to a circumferential position (Yb) in the shift intermediate area (Pb) in a case where the switching pin (73, 74, 83, 84) is active to enter and engage the guide groove (44, 54); wherein the protective element (101, 102) has a fixed side part (101a, 102a) which is fixed to the guide groove cylinder portion (43D, 53D), and a generally circular arc-shaped switching pin entry preventing part (101b, 102b) which is arranged in the guide groove (44, 54) in the certain circumferential region (Zab), wherein the fixed side part (101a, 102a) and the switching pin entry preventing part (101b, 102b) are formed continuously, and when the switching pin (73, 74, 83, 84) is advanced in the specific circumferential area (Zab), the switching pin entry preventing member (101b, 102b) comes into contact with the tip surface (73df) of the switching pin (73, 74, 83, 84) to prevent the switching pin (73, 74, 83, 84) from entering the guide groove (44, 54), and when the switching pin (73, 74, 83, 84) enters the guide groove (44, 54) in a circumferential area other than the specific circumferential area (Zab) to engage the guide groove (44, 54), the switching pin entry prohibiting member (101b, 102b) moves into contact with the outer surface (73ds) of the switching pin (73, 74, 83, 84) to maintain a state in which the switching pin (73, 74, 83, 84) is engaged in the guide groove (44, 54); wherein in a case where the outer surface (73ds) of the switching pin (73, 74, 83, 84) engaged in the guide groove (44, 54) comes into contact with the switching pin entry prohibiting part (101b, 102b) of the protective member (101, 102), the switching pin entry prohibiting part (101b, 102b) is pressed and elastically deformed; characterized by , that the protective element (101, 102) is an elastic, generally circular-arc-shaped band-like element, the switching pin entry prevention part (101b, 102b) of the protective element (101, 102), which extends continuously from the fixed side part (101a, 102a) in the direction of a retraction side opposite to an advance side in the direction of rotation of the cam carrier (43, 53), the fixed side part (101a, 102a) is attached to a groove side wall portion (W2) having a first groove side wall surface (F2) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), and the switching pin entry prohibiting part (101a, 102a) has a base portion (101ba, 102ba) extending continuously from the fixed side portion (101a, 102a) and in contact with the first groove side wall surface (F2) at the predetermined circumferential position (Yaa) slightly offset forward from the displacement start inclination region (Pa) in the rotation direction of the cam carrier (43, 53), and the switching pin entry prohibiting part (101a, 102a) extends from the base portion (101ba, 102ba) toward the recess side opposite to the advance side in the rotation direction of the cam carrier (43, 53) while approaching the second groove side wall surface (F1) of the groove side wall surfaces (F1, F2), and a rear end portion (101be, 102be) of the switching pin entry prohibiting part (101a, 102a) is arranged in the sliding intermediate region (Pb). [2] Variable valve device (40) comprising: a camshaft (42, 52) rotatably provided in a cylinder head (3) of an internal combustion engine (E); a cam carrier (43, 53) comprising a cylindrical member axially slidably fitted around an outer circumference of the camshaft (42, 52) while the rotation thereof relative to the camshaft (42, 52) is restricted, wherein the cam carrier (43, 53) has a plurality of cam lobes (43A, 43B, 53A, 53B) formed on an outer peripheral surface of the cam carrier (43, 53) and adjacent to each other in an axial direction and having different cam profiles, wherein the cam carrier (43, 53) is integrated with a guide groove cylindrical portion (43D, 53D) provided with a guide groove (44, 54) defined like a channel by a groove bottom surface (G) and groove side wall surfaces (F1, F2) on opposite sides of the groove bottom surface (G); and a cam switching mechanism (70, 80) which advances and retracts a switching pin (73, 74, 83, 84) so ​​that the switching pin (73, 74, 83, 84) is able to engage and disengage from the guide groove (44, 54), wherein the cam carrier (43, 53) is guided and displaced in the axial direction during rotation through the guide groove (44, 54) with the advanced switching pin (73, 74, 83, 84) engaged therein in order to switch the cam lobe (43A, 43B, 53A, 53B) acting on a valve (41, 51), wherein a second groove side wall surface (F1) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), which groove side wall surface (F1) is brought into sliding contact with the switching pin (73, 74, 83, 84) and is pressed thereby to slide the cam carrier (43, 53), has a sliding side wall surface (Faz) which extends from a sliding start inclination region (Pa) at which the cam carrier (43) starts to slide, through a sliding intermediate region (Pb) to a sliding end inclination region (Pz) at which the cam carrier (43) stops the sliding, and the cam carrier (43, 53) is provided with a protective element (201, 202) which prevents the entry of the switching pin (73, 74, 83, 84) into the guide groove (44, 54) in a certain circumferential area (Zab) from a certain circumferential position (Yaa) in a rotation direction of the cam carrier (43, 53) slightly offset forward from the shift start inclination area (Pa) to a circumferential position (Yb) in the shift intermediate area (Pb) in a case where the switching pin (73, 74, 83, 84) is active to enter and engage the guide groove (44, 54); wherein the protective element (201, 202) has a fixed side part (201a, 202a) which is fixed to the guide groove cylinder portion (43D, 53D), and a generally circular arc-shaped switching pin entry preventing part (201b, 202b) which is arranged in the guide groove (44, 54) in the certain circumferential region (Zab), wherein the fixed side part (201a, 202a) and the switching pin entry preventing part (201b, 202b) are formed continuously, and when the switching pin (73, 74, 83, 84) is advanced in the specific circumferential area (Zab), the switching pin entry preventing member (201b, 202b) comes into contact with the tip surface (73df) of the switching pin (73, 74, 83, 84) to prevent the switching pin (73, 74, 83, 84) from entering the guide groove (44, 54), and when the switching pin (73, 74, 83, 84) enters the guide groove (44, 54) in a circumferential area other than the specific circumferential area (Zab) to engage the guide groove (44, 54), the switching pin entry prohibiting member (201b, 202b) moves into contact with the outer surface (73ds) of the switching pin (73, 74, 83, 84) to maintain a state in which the switching pin (73, 74, 83, 84) is engaged in the guide groove (44, 54); wherein in a case where the outer surface (73ds) of the switching pin (73, 74, 83, 84) engaged in the guide groove (44, 54) comes into contact with the switching pin entry prohibiting part (201b, 202b) of the protective member (201, 202), the switching pin entry prohibiting part (201b, 202b) is pressed and elastically deformed; characterized by , that the protective element (201, 202) is an elastic, generally circular-arc-shaped steel wire element, an outer peripheral surface of a groove side wall portion (W1) having the second groove side wall surface (F1) partially including the displaceable side wall surface (Faz) of the guide groove cylinder portion (43D, 53D) is provided with a circumferential groove (45v) having an axial width between an area axially outside the displacement start inclination area (Pa) across a width of the protective member (201, 202) and the sliding intermediate area (Pb) and having a groove depth substantially equal to a radial thickness of the protective member (201, 202), wherein the switching pin entry preventing part (201b, 202b) of the protective element (201, 202), which extends continuously from the fixed side part (201a, 202a), extends to a retraction side opposite to an advancement side in the rotation direction of the cam carrier (43, 53), and the protective element (201, 202) has an extension part (201c, 202c) which extends to the retraction side from the switching pin entry preventing part (201b, 202b), the fixed side part (201a, 202a) is fitted and fixed in a narrow circumferential groove part (45vn) axially outwardly from the displacement start inclination area (Pa) of the circumferential groove (45v), the switching pin entry preventing part (201b, 202b) has a base portion (201ba, 202ba) which extends continuously from the fixed side part (201a, 202a) and is in contact with the second groove side wall surface (F1) having the displaceable side wall surface (Faz) at the predetermined circumferential position (Yaa) slightly offset forward from the displacement start inclination region (Pa) in the rotation direction of the cam carrier (43, 53), wherein the switching pin entry preventing part (201b, 202b) leaves the second groove side wall surface (F1) at the base portion (201ba, 202ba) and extends toward the retraction side opposite the advancement side in the rotation direction of the cam carrier (43, 53) along a groove opening of the guide groove (44, 54), and the Switch pin entry prevention part (201b, 202b) has a rear portion (201be, 202be) which is continuous with the extension part (201c,202c) and is in contact with the second groove side wall surface (F1) at the sliding intermediate region (Pb), and, the extension part (201c, 202c) is inserted in a wide circumferential groove part (45vw) which corresponds to the displaceable side wall surface (Faz), axially inwardly from the displacement start inclination region (Pa) of the circumferential groove (45v). [3] Variable valve device (40) comprising: a camshaft (42, 52) rotatably provided in a cylinder head (3) of an internal combustion engine (E); a cam carrier (43, 53) comprising a cylindrical member axially slidably fitted around an outer circumference of the camshaft (42, 52) while the rotation thereof relative to the camshaft (42, 52) is restricted, wherein the cam carrier (43, 53) has a plurality of cam lobes (43A, 43B, 53A, 53B) formed on an outer peripheral surface of the cam carrier (43, 53) and adjacent to each other in an axial direction and having different cam profiles, wherein the cam carrier (43, 53) is integrated with a guide groove cylindrical portion (43D, 53D) provided with a guide groove (44, 54) defined like a channel by a groove bottom surface (G) and groove side wall surfaces (F1, F2) on opposite sides of the groove bottom surface (G); and a cam switching mechanism (70, 80) which advances and retracts a switching pin (73, 74, 83, 84) so ​​that the switching pin (73, 74, 83, 84) is able to engage and disengage from the guide groove (44, 54), wherein the cam carrier (43, 53) is guided and displaced in the axial direction during rotation through the guide groove (44, 54) with the advanced switching pin (73, 74, 83, 84) engaged therein in order to switch the cam lobe (43A, 43B, 53A, 53B) acting on a valve (41, 51), wherein a second groove side wall surface (F1) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), which groove side wall surface (F1) is brought into sliding contact with the switching pin (73, 74, 83, 84) and is pressed thereby to slide the cam carrier (43, 53), has a sliding side wall surface (Faz) which extends from a sliding start inclination region (Pa) at which the cam carrier (43) starts to slide, through a sliding intermediate region (Pb) to a sliding end inclination region (Pz) at which the cam carrier (43) stops the sliding, and the cam carrier (43, 53) is provided with a protective element (301, 302) which prevents the entry of the switching pin (73, 74, 83, 84) into the guide groove (44, 54) in a certain circumferential area (Zab) from a certain circumferential position (Yaa) in a rotation direction of the cam carrier (43, 53) slightly offset forward from the shift start inclination area (Pa) to a circumferential position (Yb) in the shift intermediate area (Pb) in a case where the switching pin (73, 74, 83, 84) is active to enter and engage the guide groove (44, 54); wherein the protective element (301, 302) has a fixed side part (301a, 302a) which is fixed to the guide groove cylinder portion (43D, 53D), and a generally circular arc-shaped switching pin entry preventing part (301b, 303b) which is arranged in the guide groove (44, 54) in the certain circumferential region (Zab), wherein the fixed side part (301a, 302a) and the switching pin entry preventing part (301b, 302b) are formed continuously, and when the switching pin (73, 74, 83, 84) protrudes in the certain circumferential area (Zab), the switching pin entry preventing part (301b, 302b) comes into contact with the tip surface (73df) of the switching pin (73, 74, 83, 84) to prevent the switching pin (73, 74, 83, 84) from entering the guide groove (44, 54), and when the switching pin (73, 74, 83, 84) enters the guide groove (44, 54) in a circumferential area other than the specific circumferential area (Zab) to engage the guide groove (44, 54), the switching pin entry prohibiting member (301b, 302b) moves into contact with the outer surface (73ds) of the switching pin (73, 74, 83, 84) to maintain a state in which the switching pin (73, 74, 83, 84) is engaged in the guide groove (44, 54); wherein in a case where the outer surface (73ds) of the switching pin (73, 74, 83, 84) engaged in the guide groove (44, 54) comes into contact with the switching pin entry prohibiting part (301b, 302b) of the protective member (301, 302), the switching pin entry prohibiting part (301b, 302b) is pressed and elastically deformed; characterized by , that the protective element (301, 302) is an elastic, generally circular-arc-shaped steel wire element, the switching pin entry preventing part (301a, 302a) of the protective element (301b, 302b), which extends continuously from the fixed side part (301a, 302a), extends to a retraction side opposite to an advancement side in the rotation direction of the cam carrier (43, 53), the fixed side part (301a, 302a) is fitted and fixed in a fitting insertion groove (46) formed in a groove side wall portion (W2) having a first groove side wall surface (F2) of the groove side wall surfaces (F1, F2) on the opposite sides of the guide groove (44, 54), and the switching pin entry preventing part (301b, 302b) has a base portion (301ba, 302ba) extending continuously from the fixed side portion (301a, 302a) and in contact with an outer peripheral edge of the first groove side wall surface (F2) at the predetermined circumferential position (Yaa) slightly offset forward from the displacement start inclination region (Pa) in the rotation direction of the cam carrier (43, 53), wherein the switching pin entry preventing part (301b, 302b) extends from the base portion (301ba, 302ba) to the retraction side opposite the advance side in the rotation direction of the cam carrier (43, 53) along a groove opening of the guide groove (44, 54) while approaching the second groove side wall surface (F1) of the groove side wall surfaces (F1, F2), and Switch pin entry prohibiting part (301b, 302b) has a curved rear portion (301be, 302be) arranged in the sliding intermediate region (Pb), the tip of the rear portion (301be,302be) is in contact with the groove bottom surface (G).

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