JP2013253524A - Mounting structure of cam angle sensor for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in a rotation angle detection accuracy caused by a thermal expansion change.SOLUTION: A mounting structure of a cam angle sensor 74 detecting a rotation angle of a camshaft 44 rotatably supported by a cylinder head 18 of an internal combustion engine 10 is used for mounting a cam angle sensor 74 to a cylinder head cover 20 covering the cylinder head. An axis of the cam angle sensor 74 passes an axis 48 of the camshaft 44 and is vertical to the axis of the camshaft 44 by defining a vertical surface in a reciprocating direction 26 of a piston as a reference surface, and the specific angle of the axis with respect to the reference surface is 0-90°, preferably, 20-50° or more preferably, 30-40°.

Description

  The present invention relates to a cam angle sensor for an internal combustion engine, and more particularly to a cam angle sensor mounting structure.

  In an internal combustion engine mounted on a vehicle such as an automobile, the camshaft rotation angle is detected by a cam angle sensor, also called a cam position sensor, for the purpose of cylinder discrimination and camshaft timing detection. The camshaft is rotatably supported by a bearing provided on the cylinder head, and a timing rotor is integrally provided on the camshaft. For example, as described in Patent Document 1 below, the cam angle sensor is attached to the cylinder head cover so that its detection portion is positioned in the vicinity of the timing rotor.

JP 2005-113850 A

[Problems to be Solved by the Invention]
When the internal combustion engine is operated, the temperature of the cylinder head cover also rises, so that the main part of the cylinder head cover is displaced away from the cylinder head due to expansion deformation. Therefore, as described in Patent Document 1, when the cam angle sensor is mounted so as to extend in the vertical direction or close to the upper direction of the cam shaft, the cam angle is increased along with the upward displacement of the cylinder head cover. The sensor is displaced away from the timing rotor. As a result, the rotation angle detection accuracy of the cam angle sensor decreases due to the decrease in detection sensitivity of the cam angle sensor.

  Further, when the cam angle sensor is attached to the cylinder head cover so as to extend in the horizontal direction or a direction close to the side of the cam shaft, the direction of the axis of the cam angle sensor changes with the upward displacement of the cylinder head cover. It deviates from the radial direction of the timing rotor. As a result, the correlation between the relative position of the detection unit of the cam angle sensor with respect to the protrusion of the timing rotor and the rotation angle of the timing rotor changes, and the cam shifts due to the occurrence of phase shift in the output of the cam angle sensor. The rotation angle detection accuracy of the angle sensor decreases.

  Further, in an internal combustion engine mounted on a vehicle such as an automobile, a PCV (Positive Crankcase Ventilation) chamber is formed by a cylinder head cover above a camshaft as part of a blow-by gas reduction device. The PCV chamber is partitioned from the chamber in which the camshaft is provided by a baffle plate.

  When the cam angle sensor is mounted so as to extend in the vertical direction or close to the cam shaft, the volume of the PCV chamber is reduced, or the shape of the PCV chamber or baffle plate is restricted. Inevitable. For this reason, the amount of oil carried away in the blow-by gas flowing into the PCV chamber is increased, and the oil draining performance is reduced.

The present invention has been made in view of the above-described problems related to a cam angle sensor that detects the rotation angle of a camshaft. And the main subject of this invention is the attachment of the cam angle sensor which can reduce the fall of the detection sensitivity of a cam angle sensor, or the phase shift of an output, without the fall of the oil draining property in a PCV room in the future. Is to provide a structure.
[Means for Solving the Problems and Effects of the Invention]

  According to the present invention, the main problem described above is a cam angle sensor mounting structure for detecting a rotation angle of a camshaft rotatably supported by a cylinder head of an internal combustion engine, and a cylinder head cover that covers the cylinder head A cam angle sensor mounting structure with respect to the camshaft sensor, the axis passing through the camshaft axis and perpendicular to the reciprocating direction of the piston as a reference plane, the cam angle sensor axis being perpendicular to the camshaft axis, and This is achieved by an internal combustion engine cam angle sensor mounting structure (structure of claim 1) characterized in that it forms a predetermined angle larger than 0 ° and smaller than 90 ° with respect to the reference plane.

  According to the above configuration, the axis of the cam angle sensor is perpendicular to the axis of the cam shaft and forms a predetermined angle greater than 0 ° and less than 90 ° with respect to the reference plane. Therefore, for example, compared with a case where the axis of the cam angle sensor is 90 ° with respect to the reference plane, it is possible to reduce a decrease in the detection sensitivity of the cam angle sensor. Compared to the case of °, the phase shift of the output of the cam angle sensor can be reduced. Therefore, the camshaft rotation angle can be detected with good accuracy regardless of the temperature of the internal combustion engine as compared with the case where the axis of the cam angle sensor does not form a predetermined angle with respect to the reference plane.

  Further, according to the above configuration, it is unnecessary to make the detection unit of the cam angle sensor more sensitive than necessary. For example, the temperature of the cylinder head cover is detected, and the cam angle is detected based on the detected temperature. It is also unnecessary to correct the phase shift of the sensor output.

  According to the invention, in the above-described configuration, the predetermined angle is configured to be 20 ° or more and 50 ° or less (configuration of claim 2).

  As will be described in detail later, the greater the angle formed by the cam angle sensor axis with respect to the reference plane, the greater the decrease in the detection sensitivity of the cam angle sensor. Conversely, the angle formed by the cam angle sensor axis with respect to the reference plane increases. The smaller the value, the larger the output phase shift. According to the above configuration, since the predetermined angle is not less than 20 ° and not more than 50 °, it is possible to more effectively reduce the detection sensitivity of the cam angle sensor and the output phase shift, thereby further improving the accuracy. The rotation angle of the camshaft can be detected with high accuracy.

  According to the invention, the predetermined angle is configured to be not less than 30 ° and not more than 40 ° (configuration of claim 3).

  According to the above configuration, it is possible to more effectively reduce the detection sensitivity of the cam angle sensor and the phase shift of the output of the cam angle sensor, and thereby the camshaft rotation angle can be more accurately improved. Can be detected.

  According to the present invention, in the above configuration, the cylinder head cover defines a PCV chamber on a side opposite to the cylinder head with respect to the camshaft, and the upper limit value of the predetermined angle is The cam angle sensor is configured to be equal to or less than a maximum value within a range in which the cam angle sensor does not interfere with the PCV chamber.

According to the above configuration, it is possible to avoid the volume of the PCV chamber from being reduced and the shape of the PCV chamber and the baffle plate from being restricted. By installing the cam angle sensor, the oil drainage in the PCV chamber can be avoided. It is possible to reliably avoid a decrease in performance.
[Preferred embodiment of problem solving means]

  According to one preferable aspect of the present invention, in the above configuration, the camshaft is an intake camshaft, and the cam angle sensor is configured to detect a rotation angle of the intake camshaft.

  According to another preferred embodiment of the present invention, in the above configuration, the camshaft is an intake camshaft and an exhaust camshaft, and the cam angle sensor corresponds to the intake camshaft and the exhaust camshaft. And the rotation angles of the intake camshaft and the exhaust camshaft are respectively detected.

It is sectional drawing which shows one Embodiment of the attachment structure of the cam angle sensor by this invention applied to the internal combustion engine which has a valve mechanism of a roller rocker arm type. It is explanatory drawing which expands and shows the principal part of the attachment structure of the cam angle sensor by the side of intake shown in FIG. It is a figure which shows the pulse-shaped output signal of a cam angle sensor about the case where it is normal (solid line), and the phase error to the advancing side has arisen (virtual line). The angle θ formed by the cam angle sensor axis with respect to the reference plane, the distance change ΔL between the cam angle sensor detector and the outer diameter of the pulsar teeth associated with the change in the cylinder head cover temperature, and the cam angle sensor axis It is a graph which shows the relationship between the variation | change_quantity (DELTA) (alpha) of the angle which makes with respect to the surface of a pulsatis.

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

  In FIG. 1, 10 indicates a peripheral portion of a combustion chamber of an on-vehicle internal combustion engine, and 12 and 14 indicate an intake system valve mechanism and an exhaust system valve mechanism, respectively. Reference numerals 16, 18, and 20 denote a cylinder block, a cylinder head, and a cylinder head cover, respectively. The cylinder head 18 is fixed to the upper end of the cylinder block 16 by a bolt 22, and the cylinder head cover 20 covers the cylinder head by being fixed to the upper end of the cylinder head 18 by a bolt 24.

  Although not shown in FIG. 1, the cylinder block 16 has a plurality of cylinder bores that reciprocally receive the piston, and 26 indicates a direction in which the piston reciprocates within the cylinder bore. Although not shown in FIG. 1, the piston cooperates with the cylinder block 16 and the cylinder head 18 to define a variable volume combustion chamber. The intake port and the exhaust port that open to the combustion chamber are respectively Opened and closed by the intake valve 28 and the exhaust valve 30. The intake valve 28 and the exhaust valve 30 are urged to the closed position by return springs 32 and 34, respectively.

  The intake valve 28 and the exhaust valve 30 are driven to open and close by a roller rocker arm 36 of the intake system valve mechanism 12 and a roller rocker arm 38 of the exhaust system valve mechanism 14, respectively. The rocker arm 36 is pivotally supported at one end by a lash adjuster 40 and engaged with the upper end of the stem portion of the intake valve 28 at the other end. A roller 42 is rotatably provided between both ends of the rocker arm 36, and the roller 42 is engaged with a cam lobe 46 of the intake camshaft 44.

  The camshaft 44 can rotate around the rotation axis 48 in the clockwise direction as viewed in FIG. 1, and the rotation axis 48 extends in the direction in which the cylinder bores are arranged, that is, in the direction perpendicular to the plane of FIG. When the camshaft 44 rotates about the rotation axis 48, the distance between the contact point between the roller 42 and the cam lobe 46 and the rotation axis 48 changes. Therefore, the rocker arm 36 is swung around the pivot point of the lash adjuster 40 according to the change in the distance, and the intake valve 28 is reciprocated to be driven to open and close.

  Although not shown in detail in FIG. 1, the exhaust system valve mechanism 14 is the same as the intake system valve mechanism 12 except that the left and right sides are opposite to the intake system valve mechanism 12. And operate similarly. That is, when the exhaust camshaft 50 rotates around the rotation axis 52 extending in parallel with the rotation axis 48 in the clockwise direction as viewed in FIG. Is driven to open and close.

  The cylinder head cover 20 defines PCV chambers 54 and 56 above the intake camshaft 44 and the exhaust camshaft 50, that is, on the opposite side of the camshafts 44 and 50 from the cylinder head 18, respectively. . The PCV chambers 54 and 56 extend in parallel to each other in a direction perpendicular to the paper surface of FIG.

  The PCV chamber 54 on the intake side is partitioned by a baffle plate 58 from a space 60 in which the intake camshaft 44 is disposed, and the baffle plate 58 partially has a double structure vertically. Below the baffle plate 58, an oil delivery pipe 62 for supplying lubricating oil to the camshaft 44 is disposed, and the pipe 62 is supported by the baffle plate 58.

  On the other hand, the exhaust-side PCV chamber 56 is partitioned by a baffle plate 64 from a space 66 in which the exhaust camshaft 50 is disposed, and is separated into an upper chamber and a lower chamber by a sub baffle plate 68. Below the baffle plate 64, an oil delivery pipe 70 for supplying lubricating oil to the camshaft 50 is disposed, and the pipe 70 is supported by the baffle plate 64.

  The intake camshaft 44 is integrally formed with a timing rotor 72 adjacent to one end thereof. The timing rotor 72 has three pulsar teeth (convex portions) 72A to 72C (see FIG. 2) extending around the rotation axis 48 over different angular ranges. An MRE type cam angle sensor 74 is disposed near the timing rotor 72 and is fixed to the cylinder head cover 20. The detecting portion 74A of the cam angle sensor 74 is spaced from the rotation axis 48 by a distance slightly larger than the outer diameter of the pulsar teeth 72A to 72.

  As shown in FIG. 2, a plane that passes through the rotation axis 48 of the camshaft 44 and is perpendicular to the reciprocating direction 26 of the piston is defined as a reference plane 76. Assuming that the angle formed by the axis 78 of the cam angle sensor 74 and the reference plane 76 perpendicular to the rotation axis 48 of the camshaft 44 is θ, the angle θ is a predetermined angle greater than 0 ° and smaller than 90 °. Therefore, the axis 78 of the cam angle sensor 74 is neither parallel to the reference plane 76 (θ = 0 °) nor perpendicular to the reference plane 76 (θ = 90 °).

  The cam angle sensor 74 uses the fact that the distance between the surface thereof and the detection unit 74A changes with the rotation of the timing rotor 72, and the magnetic flux passing through the detection unit 74A increases or decreases. Therefore, the rotation angle of the camshaft 44 is detected. Then, as shown in FIG. 3, the cam angle sensor 74 generates a pulsed output signal corresponding to the angle range of the pulsar teeth 72A to 72C.

  When the internal combustion engine 10 is operated, its temperature rises. Therefore, since the temperature of the cylinder head cover 20 also rises, the main part of the cylinder head cover is displaced away from the cylinder head 18 due to expansion deformation. As the distance from the cylinder head 18 increases, the accumulation of displacement increases and the amount of displacement increases. Therefore, the amount of displacement of the wall portion defining the upper edges of the PCV chambers 54 and 56 is the largest.

  The rotation angle detection accuracy of the cam angle sensor 74 depends on the distance L between the detection unit 74A of the cam angle sensor 74 and the outer diameters of the pulsar teeth 72A to 72. The distance L increases as the temperature Tcc of the cylinder head cover 20 increases, and the detection sensitivity of the cam angle sensor 74 decreases as the distance L increases, so that the detection accuracy decreases. As shown in FIG. 4, the change amount ΔL of the distance L accompanying the change of the temperature Tcc is larger as the angle θ is larger.

  Further, assuming that the intersection point between the axis 78 of the cam angle sensor 74 and the surface of the pulsar teeth is P, the rotational angle detection accuracy of the cam angle sensor 74 is as shown in FIG. Depending on the angle α formed with respect to the tangent line 80. In the illustrated embodiment, the angle α is 90 °. However, when the angle α is small, the phase of the pulse of the output signal of the cam angle sensor 74 is changed to the advance side, so that the detection accuracy is lowered. The angle α decreases as the expansion amount of the cylinder head cover 20 increases. As shown in FIG. 4, the change amount Δα of the angle α accompanying the change in the temperature Tcc, and hence the phase error Δφ of the output signal (see FIG. 3). The smaller the angle θ, the larger. In the case of a cam angle sensor that detects the rotation angle of the exhaust camshaft 50, the phase error of the output signal becomes a delay-side error.

  Therefore, in order to ensure good detection accuracy of the rotation angle by the cam angle sensor 74 regardless of the temperature Tcc of the cylinder head cover 20, the angle θ is 20 ° to 50 °, particularly 30 ° to 40 °. It is preferable that the angle is not more than °. Therefore, the predetermined angle in the embodiment is set to 20 ° to 50 °, preferably 30 ° to 40 °.

  Since the PCV chamber 54 is provided above the camshaft 44 as described above, the cam angle sensor 74 interferes with the PCV chamber 54 when the angle θ is set to a large value. That is, since it is necessary to secure a part for mounting the cam angle sensor 74, it is inevitable that the volume of the PCV chamber is reduced or the shapes of the PCV chamber and the baffle plate 58 are restricted. For this reason, it is inevitable that the amount of oil carried away in the blow-by gas flowing into the PCV chamber 54 will increase and the oil draining performance will deteriorate.

  Therefore, the upper limit value of the predetermined angle with respect to the angle θ in the embodiment is set so that the oil drainage property in the PCV chamber 54 is not deteriorated by installing the cam angle sensor 74. Is set to be equal to or less than the maximum value in a range in which it does not interfere with the PCV chamber 54.

  In the illustrated embodiment, the cam angle sensor for detecting the rotation angle of the exhaust camshaft 50 is not provided, and the rotation angle of the exhaust camshaft 50 is detected by the cam angle sensor 74. It is estimated based on the rotation angle of the cam shaft 44 for use. However, a cam angle sensor that detects the rotation angle of the exhaust camshaft 50 may be provided with the same mounting structure as the cam angle sensor 74. Further, the cam angle sensor may not be provided on the intake side but may be provided only on the exhaust side.

  As can be understood from the above description, according to the cam angle sensor mounting structure of the above-described embodiment, the decrease in the detection sensitivity of the cam angle sensor 74 due to the increase in the distance L accompanying the expansion deformation of the cylinder head cover 20 is reduced. The phase error caused by the change in the angle α can be reduced. Therefore, the cam angle sensor 74 can detect the rotation angle of the camshaft 44 with good accuracy regardless of the expansion and deformation of the cylinder head cover 20 and therefore regardless of the temperature of the internal combustion engine. Further, it is not necessary to make the detection part of the cam angle sensor 74 more sensitive than necessary.

  In particular, according to the above-described embodiment, the predetermined angle with respect to the angle θ is set to 20 ° or more and 50 ° or less, preferably 30 ° or more and 40 ° or less. Therefore, even when the angle θ is larger than 0 ° and smaller than 90 °, the detection sensitivity of the cam angle sensor 74 and the phase error can be reduced as compared with the case where the angle θ is not within the above desired range. Can be achieved.

  Further, according to the above-described embodiment, the upper limit value of the predetermined angle is set to be equal to or less than the maximum value in a range where the cam angle sensor 74 does not interfere with the PCV chamber 54. It can be reliably avoided that the oil drainability in the oil is lowered.

  It is also conceivable to reduce the phase error caused by the change in the angle α by correcting the phase of the pulse of the output signal of the cam angle sensor 74 based on the temperature of the internal combustion engine. However, the phase error due to the change in the angle α is not always uniquely related to the temperature of the internal combustion engine, and if the change amount of the angle α is to be estimated with high accuracy, for example, in the vicinity of the cam angle sensor 74 The sensor which detects the temperature of the is required.

  On the other hand, according to the above-described embodiment, it is not necessary to correct the phase of the pulse of the output signal of the cam angle sensor 74 based on the temperature of the internal combustion engine, and the change amount of the angle α is estimated with high accuracy. A temperature sensor or the like is also unnecessary.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the camshaft is configured to open and close the valve via the roller rocker arm. However, the cam angle sensor mounting structure according to the present invention may be applied to an internal combustion engine of a type in which the camshaft drives the valve to open and close via a return spring seat.

  Further, when a cam angle sensor for detecting the rotation angle of the exhaust camshaft 50 is also provided with the same mounting structure as the cam angle sensor 74, the axis angle θ of the intake cam angle sensor and the exhaust cam A value different from the angle θ of the axis of the angle sensor may be used.

  In the above-described embodiment, the internal combustion engine 10 is an in-vehicle internal combustion engine, but the cam angle sensor mounting structure according to the present invention may be applied to an internal combustion engine other than the in-vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12, 14 ... Valve mechanism, 16 ... Cylinder block, 18 ... Cylinder head, 20 ... Cylinder head cover, 36, 38 ... Roller rocker arm, 44 ... Intake camshaft, 50 ... Exhaust camshaft, 54, 56 ... PCV chamber, 58, 64 ... baffle plate, 72 ... timing rotor, 74 ... cam angle sensor, 76 ... reference plane

Claims (4)

  A cam angle sensor mounting structure for detecting a rotation angle of a camshaft rotatably supported by a cylinder head of an internal combustion engine, the camshaft sensor mounting structure for a cylinder head cover covering the cylinder head, wherein the camshaft The axis of the cam angle sensor is perpendicular to the axis of the camshaft and is greater than 0 ° and greater than 90 ° with respect to the reference surface. A cam angle sensor mounting structure for an internal combustion engine, characterized by having a small predetermined angle.   2. The cam angle sensor mounting structure for an internal combustion engine according to claim 1, wherein the predetermined angle is not less than 20 [deg.] And not more than 50 [deg.].   The cam angle sensor mounting structure for an internal combustion engine according to claim 2, wherein the predetermined angle is not less than 30 ° and not more than 40 °.   The cylinder head cover defines a PCV chamber on a side opposite to the cylinder head with respect to the camshaft, and an upper limit value of the predetermined angle is a maximum value within a range where the cam angle sensor does not interfere with the PCV chamber. The cam angle sensor mounting structure for an internal combustion engine according to any one of claims 1 to 3, wherein:

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