JP4063143B2 - Camshaft rotation angle detection structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camshaft rotation angle detection structure, and more particularly to a camshaft rotation angle detection structure that detects a rotation angle of a camshaft provided with a cam that opens and closes an intake valve or an exhaust valve of an engine.
[0002]
[Prior art]
In a DOHC type multi-cylinder engine, two camshafts for operating an intake valve and an exhaust valve are arranged in parallel with the cylinder head of the engine, and each camshaft has a camshaft rotation angle for cylinder discrimination and valve timing control. A sensor to detect is attached. Such a sensor mounting structure is shown, for example, in Japanese Patent Application Laid-Open No. H10-228707. In this sensor mounting structure, a disc-shaped shutter (detected portion) is provided on the camshaft, and a protrusion that protrudes radially outward from the outer periphery is formed on the detected portion. A sensor is disposed above the detected portion so as to face the protrusion in the vertical direction, and detects the rotation angle of the camshaft.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-329885 (page 4, FIG. 3)
[0004]
[Problems to be solved by the invention]
Here, the camshaft presses the valve lifter by the cam and opens or closes the intake valve or the exhaust valve. At this time, the camshaft receives a valve reaction force from the valve shaft of the intake valve or the exhaust valve via the valve lifter. receive. The direction of the valve reaction force is upward along the axial direction of the valve shaft, but since the valve shaft is arranged with an inclination with respect to the vertical direction, the valve reaction force also has an inclination with respect to the vertical direction. It becomes diagonally upward. Here, since the camshaft is supported by the bearing portion with a predetermined gap, the camshaft and the detected portion provided on the camshaft are operated in the valve reaction force direction by the amount of the gap during the engine operation. It will reciprocate along (slant upward direction).
[0005]
On the other hand, as described in Patent Document 1, in the conventional camshaft rotation angle detection structure, the sensor is disposed so as to face the detected portion in the vertical direction. For this reason, not only the vertical distance (interval) between the sensor and the detected portion changes, but also the horizontal positional relationship (offset amount) changes, and the camshaft rotation angle changes. There is a possibility that the detection accuracy is deteriorated.
[0006]
An object of the present invention is to suppress the influence of the valve reaction force on the rotation angle detection accuracy in the camshaft rotation angle detection structure.
[0007]
[Means for Solving the Problems]
A camshaft rotation angle detection structure according to the present invention is a camshaft rotation angle detection structure that detects a rotation angle of a camshaft provided with a cam that opens and closes an intake valve or an exhaust valve of an engine, and includes a flange and a sensor. I have. The flange is provided on the camshaft and has a detected portion for detecting a rotation angle. The sensor is arranged along the direction of the valve reaction force received by the cam from the intake valve or the exhaust valve and opposite the detected portion of the flange.
[0008]
【The invention's effect】
According to the present invention, since the sensor is arranged along the direction of the valve reaction force and facing the detected portion, the camshaft is driven in the valve reaction force direction by the valve reaction force of the intake valve or the exhaust valve. Although the distance (interval) between both changes even if it reciprocates along, it can suppress that the positional relationship (offset amount) of both in the direction perpendicular | vertical to the central axis of a sensor changes. As a result, the influence of the valve reaction force on the rotation angle detection accuracy can be suppressed, and the camshaft rotation angle detection accuracy can be improved.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(1) Configuration FIG. 1 is a perspective view of a cylinder head 1 provided with a cam rotation angle detection structure according to the present invention, FIG. 2 is a front view of the cylinder head 1, FIG. 3 is a plan view of the cylinder head 1, and FIG. 5 is a plan view of the cylinder head 1 with the cam bracket 11 removed, FIG. 5 is a partially cutaway perspective view of the cylinder head 1 cut at VV in FIG. 3, and FIG. 6 is an enlarged view of the vicinity of the cam thrust flanges 8 and 9. FIG. 7 is an enlarged perspective view of the camshaft 2. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 3, and FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. FIG. 10 is a perspective view of the sensor 21.
[0010]
As shown in FIGS. 1 to 4, intake and exhaust camshafts 2 and 3 are arranged on the upper surface of the cylinder head 1 substantially parallel to each other along a crankshaft (not shown). As shown in FIG. 2, a cam sprocket mechanism 20 to which rotation from the crankshaft is input is attached to one end of each of the camshafts 2 and 3. The intake-side and exhaust-side camshafts 2, 3 are respectively rod-shaped shaft bodies 4, 5, a plurality of cams 6, 7 provided on the outer peripheral surface of each shaft body 4, 5, and each shaft body 4, 5. Are formed of cam thrust flanges 8 and 9 for restricting the movement in the axial direction. As shown in FIG. 7, the cam 6 and the cam thrust flange 8 are formed integrally with the shaft body 4 on the outer peripheral surface of the shaft body 4. Similarly, the cam 7 and the cam thrust flange 9 are formed integrally with the shaft body 5 on the outer peripheral surface of the shaft body 5.
[0011]
As shown in FIG. 4, a plurality of lower bearing portions 14 and 15 are formed on the upper surface of the cylinder head 1 along the camshafts 2 and 3. The lower bearing portions 14 and 15 are formed with semi-cylindrical bearing surfaces that support the lower half of the shaft bodies 4 and 5. As shown in FIGS. 3 and 4, the cam bracket 11 is attached to the lower bearing portions 14 and 15. Each cam bracket 11 has upper bearing portions 12 and 13 corresponding to the lower bearing portions 14 and 15. A semi-cylindrical bearing surface that supports the upper half of the shaft bodies 4 and 5 is formed on the inner circumference of the upper bearing portions 12 and 13. The shaft body 4 is rotatably supported by the bearing surfaces of the lower bearing portion 14 and the upper bearing portion 12, and the shaft body 5 is rotatably supported by the bearing surfaces of the lower bearing portion 15 and the upper bearing portion 13.
[0012]
(Intake valve, exhaust valve)
As shown in FIG. 8, the intake valve 62 is disposed at the opening of the intake port 51 to the combustion chamber 1a, and is formed of a valve body 62a and a valve shaft 62b. The exhaust valve 72 is disposed at the opening of the exhaust port 52 to the combustion chamber 1a, and is formed of a valve main body 72a and a valve shaft 72b. Here, the axes l1 and l2 are axes passing through the central axes of the valve shafts 62b and 72b, respectively, and have a certain inclination from the vertical direction. The valve shafts 62b and 72b are attached to valve lifters 61 and 71, respectively. The cams 6 and 7 of the camshafts 2 and 3 are in contact with the upper surfaces of the caps 61c and 71c of the valve lifters 61 and 71, respectively.
[0013]
The valve lifter 61 includes a valve spring 61a, a retainer 61b, a cap 61c, and a guide 61d. The valve spring 61a is a helical coil spring, and the valve shaft 62b is inserted through the valve spring 61a. The retainer 61b holds the upper end portion of the valve spring 61a, and the end portion of the valve shaft 62b is inserted into the insertion hole formed in the center portion, and the valve shaft 62b is fixed to the retainer 61b. The cap 61c is formed with a protrusion for fixing the end of the valve shaft 62b at the center, and this protrusion is inserted into the insertion hole of the retainer 61b, so that the cap 61c is fixed to the retainer 61b. The guide 61d is a member that regulates the moving direction of the valve shaft 62b, and an end opposite to the valve main body 62a is inserted into the valve spring 61a, and the valve shaft 62b is inserted therein.
[0014]
When the camshaft 2 is rotated and the cam 6 is rotated, the cap 61 causes the cap 61c and the retainer 61b to reciprocate along the direction of the axis l1 against the elastic force of the valve spring 61a, and the intake valve 62 is opened and closed. The Here, the intake valve 62 has been described, but the same applies to the exhaust valve 72, and thus the description thereof is omitted.
[0015]
Here, since the cams 6 and 7 are arranged so as to hold the valve lifters 61 and 71 against the elastic force of the valve springs 61a and 71a from above, the cams 6 and 7 extend along the axes 11 and 12 from the valve lifters 61 and 71, respectively. Receives valve reaction force upward. 11, the shaft body 4 (shaft body 5) of the camshafts 2 and 3 is pivotally supported with a predetermined gap 100 on the bearing surfaces of the bearing portions 12 and 14 (bearing portions 13 and 15). Therefore, the cams 6 and 7 reciprocate as indicated by arrows along the directions of the axes l1 and l2.
[0016]
(Cam thrust flange)
As shown in FIGS. 6 and 7, the cam thrust flange 8 is formed in a disc shape and includes an outer peripheral portion 8 a and an inner peripheral portion 8 b having different thicknesses. The outer peripheral portion 8a is formed with steps over the entire circumference on both side surfaces of the inner peripheral portion 8b, and is formed to be relatively thinner than the inner peripheral portion 8b. The outer diameter of the outer peripheral portion 8 a is larger than the outer diameters of the shaft body 4 and the cam 6, and has the largest diameter among the configurations of the camshaft 2. As shown in FIG. 7, notches 81 a to 81 d that open to the outer peripheral side are formed in the outer peripheral portion 8 a at substantially equal intervals. Each notch 81a-81d consists of 1 to 4 notches. These notches 81 a to 81 d constitute a sensor target 81 as a detected portion for detecting the rotation angle of the cam 6. The cam thrust flange 9 of the exhaust side camshaft 3 is similarly configured.
[0017]
The bearing surfaces of the lower bearing portions 14 and 15 provided near the end portion on the cam sprocket mechanism 20 side, that is, the lower bearing portions 14 and 15 positioned further outside the cams 6 and 7 closest to the cam sprocket mechanism 20 4 to 6, semicircular grooves 16b and 17b into which the lower halves of the cam thrust flanges 8 and 9 are inserted are formed. The grooves 16b and 17b have contact surfaces 16d and 17d perpendicular to the axial direction of the camshafts 2 and 3, respectively.
[0018]
Further, the cam bracket 11 attached to the lower bearing portions 14 and 15 located closest to the cam sprocket mechanism 20 is integrally formed so as to cover both the intake side and exhaust side lower bearing portions 14 and 15. Yes. As shown in FIGS. 3 and 5, the cam bracket 11 is formed from a bracket body 11a to which a chain cover (not shown) is attached, and from the lower part of the bracket body 11a in the vertical direction toward the inside of the cylinder head 1. Cover portion 11b. As shown in FIGS. 5 and 9, the bearing surfaces of the upper bearing portions 12 and 13 formed in the cam bracket 11 correspond to the grooves 16 b and 17 b of the lower bearing portions 14 and 15, Semicircular grooves 16a and 17a into which the upper half of 9 is inserted are respectively formed. The grooves 16a and 17a have contact surfaces 16c and 17c perpendicular to the axial direction of the camshafts 2 and 3, respectively.
[0019]
When the cam bracket 11 is attached to the lower bearing portions 14 and 15 provided near the end on the cam sprocket mechanism 20 side, the upper and lower grooves 16a and 16b form an annular groove 16, and the upper and lower grooves 17a and 16b. 17 b forms an annular groove 17. At this time, the contact surface 16c and the contact surface 16d are continuous, and the contact surface 17c and the contact surface 17d are continuous.
[0020]
The widths of the grooves 16a and 16b (the width of the annular groove 16) are constant as shown in FIGS. 5 and 6, and when the cam thrust flange 8 is inserted into the annular groove 16, the inner peripheral portion 8b. Slides with the contact surfaces 16c and 16d of the annular groove 16 with a relatively narrow first gap. On the other hand, the outer peripheral portion 8a has the contact surfaces 16c, 16d of the annular groove 16 and a second gap larger than the first gap, and does not contact the contact surfaces 16c, 16d. Further, the inner diameter of the annular groove 16 is formed larger than the outer diameter of the cam thrust flange 8, and the end of the outer peripheral portion 8a of the cam thrust flange 8 does not contact the inner wall of the annular groove 16 (grooves 16a, 16b). That is, the sensor target 81 formed on the outer peripheral portion 8 a does not contact the inner wall of the annular groove 16. When the cam thrust flange 8 rotates together with the shaft body 4, the axial movement of the camshaft 2 is restricted by the inner peripheral portion 8 b and the contact surfaces 16 c and 16 d of the annular groove 16. That is, the cam thrust flange 8 and the annular groove 16 serve to position the cam shaft 2 in the axial direction. The same applies to the cam thrust flange 9 and the annular groove 17 of the exhaust side camshaft 3.
[0021]
[Sensor]
The sensor 21 is a detection device for detecting a rotation angle, and includes a sensor main body 21a and a flange portion 21b as shown in FIG. The sensor main body 21a is formed in a cylindrical shape, and has a detection part 21d for detecting the sensor target 81 at the tip part. The flange portion 21b is provided at the end of the sensor body 21a opposite to the side where the detection portion 21d is provided, and an insertion hole 21c is formed.
[0022]
As shown in FIGS. 5 and 9, the cover portion 11b has a sensor insertion port 11c and a screw hole 11d. The sensor insertion opening 11c is formed to open into the grooves 16a and 17a from the upper surface of the cover portion 11b. Further, the sensor insertion port 11 c is formed so that the axes 11 ′ and 12 ′ passing through the center thereof pass through the center of the cam thrust flange 8. The axes l1 ′ and l2 ′ are parallel to the axes l1 and l2 passing through the central axes of the valve shafts 62b and 72b of the intake valve 62 and the exhaust valve 72. 11 d of screw holes are formed in the cover part 11b inside the sensor insertion port 11c along axis | shaft l1 ', l2'. The sensor 21 has a sensor body 21a inserted into the sensor insertion port 11c so that the detection portion 21d faces the groove 16a, and a bolt is screwed into the screw hole 11d through the insertion hole 21c of the flange portion 21b. It is fixed to the upper surface of the part 11b. At this time, the detection unit 21d of the sensor 21 is disposed on the axis l1 ′ along the axis l1 that is the direction of the valve reaction force, and opposed to the sensor target 81 of the cam thrust flange 8 from above. Here, the intake-side sensor 21 has been described, but the same applies to the exhaust-side sensor 22.
[0023]
FIG. 11 is an explanatory diagram for explaining the reciprocal movement of the sensor target 81 due to the valve reaction force. FIG. 4A shows a state in which the shaft body 4 of the camshaft 2 moves relative to the bearing surfaces of the bearing portions 12 and 14. As described above, the shaft 11 is the direction of the valve shaft 62b of the intake valve 62, and is the direction of receiving the valve reaction force by the intake valve 62. As shown in the figure, the shaft body 4 is rotatably supported on the bearing surfaces of the bearing portions 12 and 14 with a predetermined gap 100. When the shaft body 4 receives the valve reaction force via the cam 6, the shaft body 4 reciprocates along the shaft 11 by the gap 100. FIG. 4B is a diagram showing the positional relationship between the sensor target 81 and the sensor 21. As described above, when the shaft body 4 is reciprocated along the axis l1, the cam thrust flange 8 is also reciprocated in the direction of the shaft l1 ′, so that the distance between the detection portion 21d of the sensor 21 and the sensor target 81 is increased. (Interval) also changes. However, since the sensor 21 and the sensor target 81 are disposed so as to face each other on the axis l1 ′ that is the same direction as the direction in which the sensor target 81 reciprocates, the offset amount between the sensor 21 and the sensor target 81 ( The change in the positional relationship in the direction perpendicular to the axis l1 ′ is suppressed. Here, the sensor 21 and the sensor target 81 on the intake side have been described, but the same applies to the sensor 22 and the sensor target 91 on the exhaust side.
[0024]
(2) In the cam rotation angle detection structure configured as described above, the sensor 21 is disposed on the axis l1 ′ passing through the center of the cam thrust flange 8 along the valve reaction force direction. Even if the flange 8 (sensor target 81) reciprocates along the axis l1 ′, the change in the offset amount can be suppressed, although the interval between the sensor 21 and the sensor target 81 changes. As a result, the influence of the valve reaction force on the rotation angle detection can be suppressed, and the detection accuracy of the rotation angle of the camshaft 4 by the sensor 21 and the sensor target 81 can be improved.
[0025]
By providing the sensor target 81 on the cam thrust flange 8 that restricts the movement of the camshaft 2 in the axial direction, even when the camshaft 2 is thermally expanded in the axial direction when the engine is operating, the camshaft 2 has the cam thrust flange 8 mounted. It expands in the axial direction as a base point. For this reason, the sensor target 81 provided on the cam thrust flange 8 does not shift in the axial direction due to thermal expansion. In this respect as well, the detection accuracy of the rotation angle of the camshaft 2 can be improved.
[0026]
Further, when the cam thrust flange 8 and the sensor target 81 are arranged apart from each other in the axial direction of the camshaft 2, the positional relationship between the sensor target 81 and the sensor 21 is shifted due to the dimensional variation of each part of the camshaft 2. Although there is a possibility, it can prevent that the positional relationship of both arises by providing the sensor target 81 in the thrust flange 8. FIG.
[0027]
A cam thrust flange 8 having a sensor target 81 is integrally formed with a groove 16a (annular groove 16) in which a contact surface 16c is formed and a sensor insertion opening 21a to which the sensor 21 is attached to the cam bracket 11 as one member. Therefore, no other parts are interposed between the positioning of the sensor target 81 and the positioning of the sensor 21. Therefore, it is possible to prevent the positional tolerance between the sensor target 81 and the sensor 21 from being accumulated due to accumulation of dimensional tolerances and mounting play of a plurality of parts, and the detection accuracy by the sensor 21 can be improved.
[0028]
Since the cam thrust flange 8 is inserted into the annular groove 16 formed on the bearing surface to restrict the axial movement of the camshaft 2, there is no need to provide a plurality of cam thrust flanges 8, and the length of the camshaft 2 is long. Thus, the camshaft 2 can be prevented from increasing in weight.
[0029]
Since the sensor target 81 is formed on the outer peripheral portion 8a of the cam thrust flange 8, the outer diameter of the sensor target 81 is increased, and the detection sensitivity of the sensor 21 can be improved. Further, since the sensor target 81 is provided on the outer peripheral portion 8a of the cam thrust flange 8 having the largest outer diameter in the configuration of the camshaft 2, the outer diameter of the sensor target 81 is large, and the detection accuracy of the cam rotation angle can be improved. .
[0030]
A sensor target 81 is provided on the outer peripheral portion 8a formed with steps on both side surfaces of the inner peripheral portion 8b of the cam thrust flange 8, so that the sensor target 81 does not contact the cylinder head 1 and the cam bracket 11 (the inner wall of the annular groove 16). Therefore, when the notches 81a to 81d, which are sensor targets 81, are formed by a cutting tool, the cylinder head 1 is prevented from being seized, slidable, and worn by burrs generated around the notches. Damage and wear can be prevented. Moreover, since the deburring process of the sensor target 81 can be shortened, cost reduction can be achieved. Furthermore, since it is only necessary to provide the outer peripheral portion 8a within the minimum necessary range for providing the sensor target 81, a sufficient sliding surface can be secured by the inner peripheral portion 8b, and the surface pressure becomes too high. Can be prevented.
[0031]
By forming the notches 81a to 81d in the outer peripheral portion 8a of the cam thrust flange 8, the sensor target 81 is formed integrally with the cam thrust flange 8, so that the accuracy of the installation position of the sensor target 81 is improved and the weight of the camshaft 2 is increased. Reduction can be achieved. In addition, the sensor target 81 can be simply configured by the notches 81a to 81d.
[0032]
Japanese Patent Laid-Open No. 2001-73826 describes a camshaft rotation angle detection structure in which a cam thrust flange is disposed on the opposite side of the cam sprocket mechanism. In this way, the cam thrust flange is opposite to the cam sprocket mechanism. When arranged on the side, the distance between the cam thrust flange and the cam sprocket mechanism is large. In such a configuration, when the camshaft expands in the axial direction from the cam thrust flange as a base point due to thermal expansion, the cam movement of the cam sprocket mechanism located farthest from the cam thrust flange due to expansion of the camshaft The rotation from the crankshaft may not be accurately transmitted to the camshaft. On the other hand, if the cam thrust flange 8 is positioned by the annular groove 16 of the cam bracket 11 closest to the cam sprocket mechanism 20 as in the camshaft rotation angle detection structure according to the present embodiment, the cam thrust flange 8 and the cam The distance from the sprocket mechanism 20 is small, and the movement allowance of the cam sprocket mechanism 20 in the axial direction due to thermal expansion of the camshaft 2 is small, so that rotation from the crankshaft can be transmitted to the camshaft 2 with high accuracy.
[0033]
Further, since the cam thrust flange 8 is formed integrally with the shaft main body 4, the positional accuracy of the cam thrust flange 8 can be improved, and the assembly work of the cam thrust flange 8 to the shaft main body 4 can be omitted. it can.
[0034]
The operational effect of the structure for detecting the rotation angle of the intake camshaft 2 has been described above. However, the same operational effect as described above can be obtained when the rotational angle of the exhaust camshaft 3 is detected.
[0035]
(3) Other Embodiments (A) In the above embodiment, the sensor targets 81 and 91 are provided on the cam thrust flanges 8 and 9, but the sensor target is provided on a sensor plate that is a separate member from the cam thrust flanges 8 and 9. May be. Even in this case, if the sensor is arranged along the direction in which the valve reaction force acts and is opposed to the sensor target, a change in the offset amount between the sensor and the sensor target can be suppressed.
[0036]
(B) In the above description, the cams 6 and 7 and the cam thrust flanges 8 and 9 are formed integrally with the shaft bodies 4 and 5, but when the camshafts 2 and 3 are assembly shafts as shown in FIG. The cams 6 and 7 and the cam thrust flanges 8 and 9 may be formed as separate members from the camshafts 2 and 3, and these may be fitted and fixed to the shaft bodies 4 and 5. Further, either one of the cams 6 and 7 or the cam thrust flanges 8 and 9 may be formed as a separate member.
[0037]
In this case, it is necessary to attach the cam thrust flange 8 formed separately to the shaft body 4, but in order to integrally form the cam thrust flange 8 and the sensor target 81, the plate on which the sensor target 81 is provided is formed by a separate member. Compared with the case of forming, the number of parts can be reduced and the manufacturing cost can be reduced. Even in this case, since the sensor target 81 is formed integrally with the cam thrust flange 8, the position accuracy of the sensor target can be improved.
[0038]
(C) In the above embodiment, the rotation angles of the intake-side and exhaust-side camshafts 2 and 3 are detected, but when it is not necessary to detect the rotation angle of the exhaust-side camshaft 3, the cam thrust flange 9 There is no need to provide the sensor target 91, and there is no need to provide the sensor 22.
[0039]
(D) In the above embodiment, each cam bracket 11 is provided separately for each cylinder, but each cam bracket may be formed integrally over all cylinders. In this case, the rigidity of the cam bracket can be improved.
[0040]
(E) In the above embodiment, the sensor target 81 is constituted by the notches 81a to 81d. However, electrical marking, magnetic marking, mechanical marking such as a protrusion, a groove or the like is applied to the outer peripheral surface or thrust surface of the thrust flange 8. The sensor target 81 may be configured. Also in this case, the same effect as the above embodiment can be obtained.
[0041]
(F) In the above embodiment, the detection unit 21d of the sensor 21 is opposed to the sensor target 81 of the cam thrust flange 8 from above on the axis l1 ′ along the axis l1 that is the direction of the valve reaction force. Arranged. On the other hand, when the sensor target 81 is formed on the thrust surface of the cam thrust flange 8 as shown in FIG. 13, the detection portion 21d of the sensor 21 is placed on the axis along the axis l1 ′ and the camshaft 2 You may make it arrange | position facing the sensor target 81 from the front side or back side of a longitudinal direction. Also in this case, similarly to the above embodiment, the influence of the valve reaction force on the rotation angle detection can be suppressed, and the detection accuracy of the rotation angle of the camshaft 4 by the sensor 21 and the sensor target 81 can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view of a cylinder head 1 provided with a cam rotation angle detection structure according to the present invention.
FIG. 2 is a front view of the cylinder head 1;
3 is a plan view of the cylinder head 1. FIG.
FIG. 4 is a plan view of the cylinder head 1 with a cam bracket 11 removed.
FIG. 5 is a partially cutaway perspective view of the cylinder head 1 cut along VV in FIG. 3;
FIG. 6 is an enlarged plan view near the cam thrust flange 8;
7 is an enlarged perspective view of the camshaft 2. FIG.
8 is a cross-sectional view taken along line VIII-VIII in FIG.
9 is a cross-sectional view taken along line IX-IX in FIG.
10 is a perspective view of a sensor 21. FIG.
FIG. 11 is an explanatory diagram for explaining reciprocal movement of a sensor target 81 due to valve reaction force.
FIG. 12 is an exploded perspective view of the assembly shaft.
13A and 13B are a front view and a side view when the sensor 21 is opposed to the thrust surface of the thrust flange 8;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder head 2, 3 Cam shaft 4, 5 Axis main body 6, 7 Cam 8, 9 Cam thrust flange 21, 22 Sensor 21a Sensor main body 21b Flange part 21c Insertion hole 21d Detection part 11 Cam bracket 11a Bracket main body 11b Cover part 11c Sensor Insertion port 11d Screw holes 12, 13 Upper bearing portions 14, 15 Lower bearing portions 16, 17 Annular grooves 16a, 16b, 17a, 17b Grooves 16c, 16d, 17c, 17d Contact surfaces 61, 71 Valve lifters 62, 72 Intake valves, Exhaust valve 81 Sensor target 81a Outer periphery 81b Inner periphery

Claims (14)

A camshaft rotation angle detection structure for detecting a rotation angle of a camshaft provided with a cam for opening and closing an intake valve or an exhaust valve of an engine,
A flange provided on the camshaft and having a detected portion for detecting a rotation angle;
A rotation angle detection sensor disposed along the direction of the valve reaction force received by the cam from the intake valve or the exhaust valve and facing the detected portion of the flange;
Camshaft rotation angle detection structure with The camshaft rotation angle detection structure according to claim 1, wherein the flange restricts movement of the camshaft in the axial direction. The camshaft rotation angle according to claim 2, wherein a surface that abuts on the flange to restrict axial movement of the camshaft and a sensor attachment portion to which the sensor is attached are formed as one member. Detection structure. The camshaft rotation angle detection according to claim 3, wherein the member on which the contact surface and the sensor mounting portion are formed is a cam bracket that constitutes a part of a bearing portion that rotatably supports the camshaft. Construction. The bearing portion has a lower bearing portion that supports the lower half of the camshaft, and an upper bearing portion that is formed on the cam bracket and supports the upper half of the camshaft,
The camshaft rotation angle detection structure according to claim 4, wherein grooves are formed in bearing surfaces of the lower bearing portion and the upper bearing portion, and the flange is slidably inserted into the groove. The sensor has a sensor body having a detection part for detecting the detected part at a tip part,
The sensor mounting portion is formed with a sensor insertion hole into which the sensor body is inserted along the direction of the valve reaction force.
The camshaft rotation angle detection structure according to any one of claims 1 to 5. The camshaft rotation angle detection structure according to any one of claims 1 to 6, wherein the detected portion is formed on an outer peripheral portion of the flange. The flange is formed in the groove through an inner peripheral portion having both sides inserted into the groove via a first gap, and a second gap that is formed with a step difference from the inner peripheral portion on both side surfaces. Having an inserted outer periphery,
The camshaft rotation angle detection structure according to claim 5 or 6. The camshaft rotation angle detection structure according to claim 8, wherein the detected portion is formed on the outer peripheral portion of the flange. The camshaft rotation angle detection structure according to any one of claims 1 to 9, wherein the flange has the largest outer diameter as compared with other portions of the camshaft. The camshaft rotation angle detection structure according to claim 1, wherein the detected portion is formed integrally with the flange. The flange is provided near the end of the camshaft on the cam sprocket mechanism side that transmits the rotation of the crankshaft of the engine to the camshaft.
The camshaft detection structure according to any one of claims 1 to 11. The camshaft rotation angle detection structure according to any one of claims 1 to 12, wherein the flange is formed integrally with the camshaft. The camshaft rotation angle detection structure according to any one of claims 1 to 12, wherein the camshaft is an assembly shaft.

Images