JP2008115789A - Valve lift detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect the valve lift of an engine. <P>SOLUTION: A permanent magnet 36 is attached to the side face of an intake rocker arm 28, a rocking angle sensor 37 is attached to a sensor support part 25a of a rocker arm holder positioned in the side of the permanent magnet 36, and its detection element 39 is allowed to face the moving path of the permanent magnet 36. The detection element 39 steplessly detects the rocking angle of the intake locker arm 28 from variation of magnetic field accompanying rocking of the intake rocker arm 28, that is, movement of the permanent magnet 36, and the valve lift of an intake valve corresponding to it can be known. At this time, the magnetic field generated by the permanent magnet 36 does not go away to the intake rocker arm 28 side as the intake rocker arm 28 is constituted of a non-magnetic material, and the permanent magnet 36 is arranged so that an N pole 36a and an S pole 36b line in the moving direction of the intake rocker arm 28, therefore, the amount of change of the magnetic field in the position of the detection element 39 is enlarged and thereby the detection accuracy of the valve lift is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a valve lift detection device that detects a valve lift of an engine based on a moving amount of a valve driving member.

By detecting the position of a member made of a ferromagnetic material that moves in response to rocking of the rocker arm, for example, by a rocking angle detecting means made of an electromagnetic pickup in an engine that can switch the valve lift between two levels of high and low. A technique for detecting whether the valve lift is in a high lift state or a low lift state is known from Patent Document 1 below.
JP-A-8-61023

  By the way, when controlling the valve lift and the valve timing steplessly, it is necessary to accurately detect and feed back the magnitude of the valve lift that changes every moment, that is, the rocking angle of the rocker arm. In such a case, there has been a problem that the detection accuracy of the rocker arm swing angle detecting means using the conventional electromagnetic pickup is insufficient.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to accurately detect a valve lift of an engine.

  In order to achieve the above object, according to the first aspect of the present invention, in the valve lift detection device for detecting the valve lift of the engine based on the amount of movement of the valve drive member, the valve made of a non-magnetic material. A permanent magnet is attached to the driving member so that the N pole and the S pole are arranged along the moving direction of the valve driving member, and a magnetic field is detected by a sensor arranged to face the side of the moving path of the permanent magnet. A valve lift detection device is proposed, which detects a change in the amount of movement of the valve drive member based on the change in the magnetic field.

  According to the invention described in claim 2, in addition to the structure of claim 1, the valve driving member is a rocker arm, and the sensor is attached to a swinging support portion of the rocker arm. A valve lift detection device is proposed.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect, a valve lift detection device is proposed in which the sensor is mounted above the swing support portion in the cylinder axial direction. Is done.

  According to a fourth aspect of the present invention, in the valve lift detection device for detecting the valve lift of the engine based on the amount of movement of the valve drive member, the non-magnetic material is attached to the valve drive member made of a magnetic material. A permanent magnet is attached to the non-magnetic body so that the N pole and the S pole are arranged along the moving direction of the valve driving member, and the sensor is arranged so as to face the side of the moving path of the permanent magnet. A valve lift detection device is proposed in which a change in the magnetic field is detected and the amount of movement of the valve drive member is detected based on the change in the magnetic field.

  According to the invention described in claim 5, in addition to the structure of claim 4, the valve driving member is a rocker arm, and the sensor is attached to a swinging support portion of the rocker arm. A valve lift detection device is proposed.

  According to a sixth aspect of the present invention, in addition to the configuration of the fifth aspect, a valve lift detection device is proposed in which the sensor is mounted above the swing support portion in the cylinder axial direction. Is done.

  The rocker shaft holder 25 of the embodiment corresponds to the swing support portion of the present invention, the intake rocker arm 28 of the embodiment corresponds to the valve drive member of the present invention, and the swing angle sensor 37 of the embodiment. Corresponds to the sensor of the present invention.

  According to the configuration of the first aspect, a permanent magnet is attached to the valve driving member, and the amount of movement of the valve driving member is determined based on a change in the magnetic field detected by a sensor arranged to face the side of the permanent magnet moving path. Since it is detected, the valve lift of the engine can be detected steplessly from the amount of movement of the valve drive member. At this time, since the valve drive member is made of a non-magnetic material, the magnetic field generated by the permanent magnet does not escape to the valve drive member side, and the N pole and S pole of the permanent magnet move in the direction of movement of the valve drive member. Therefore, it is possible to increase the amount of change in the magnetic field at the sensor position, thereby increasing the valve lift detection accuracy.

  According to the second aspect of the present invention, since the valve driving member is a rocker arm, and the sensor is mounted using the rocking support portion of the rocker arm, the distance from the rocking center of the rocker arm to the sensor is small. Accordingly, the distance between the N pole and the S pole of the permanent magnet can be shortened accordingly, and the entire valve lift detection device can be downsized.

  According to the third aspect of the present invention, since the sensor is mounted above the swing support portion in the cylinder axial direction, the attachment and detachment and maintenance of the sensor are facilitated.

  According to the fourth aspect of the present invention, a permanent magnet is attached to the valve driving member, and the amount of movement of the valve driving member based on a change in the magnetic field detected by a sensor arranged to face the side of the permanent magnet moving path. Therefore, the valve lift of the engine can be detected steplessly from the amount of movement of the valve drive member. At this time, since the permanent magnet is attached to the non-magnetic member attached to the valve driving member made of a magnetic material, the magnetic field generated by the permanent magnet does not escape to the valve driving member side, and the permanent magnet is made of N pole and S Since the poles are arranged along the moving direction of the valve driving member, the amount of change in the magnetic field at the sensor position can be increased, thereby improving the detection accuracy of the valve lift.

  According to the fifth aspect of the present invention, since the valve driving member is a rocker arm, and the sensor is attached using the rocking support portion of the rocker arm, the distance from the rocking center of the rocker arm to the sensor is small. Accordingly, the distance between the N pole and the S pole of the permanent magnet can be shortened accordingly, and the entire valve lift detection device can be downsized.

  According to the sixth aspect of the present invention, since the sensor is mounted above the swing support portion in the cylinder axis direction, the sensor can be easily attached and detached.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 6 show a first embodiment of the present invention. FIG. 1 is a diagram showing a valve operating mechanism of an intake valve of an engine (valve closed state). FIG. 2 is a line 2-2 in FIG. FIG. 3 is a view taken along the line 3-3 in FIG. 1, FIG. 4 is an explanatory view of the operation corresponding to FIG. 1 (valve open state), and FIG. FIG. 6 is a graph showing the positional relationship, and FIG. 6 is a graph showing the relationship of the output of the swing angle sensor with respect to the displacement of the permanent magnet.

  As shown in FIGS. 1 to 3, a piston 13 is slidably fitted to a cylinder 12 provided in a cylinder block 11 of the engine, and a piston 13 is connected to a cylinder head 14 coupled to the upper surface of the cylinder block 11. A combustion chamber 15 facing the top surface is formed. An intake port 17 that communicates with the combustion chamber 15 via an intake valve seat 16 is formed in the cylinder head 14, and a valve stem 18 b of the intake valve 18 that opens and closes the intake valve seat 16 with the valve head 18 a is provided in the cylinder head 14. Is slidably supported by a valve guide 19 provided in Both ends of the valve spring 20 disposed in a compressed state on the outer periphery of the valve stem 18b are in contact with a retainer 21 provided on the cylinder head 14 and a retainer 22 provided on the upper end of the valve stem 18b, respectively. Thus, the intake valve 18 is urged in the valve closing direction in which the valve head 18 a is seated on the intake valve seat 16.

  A camshaft 26 is rotatably supported between a camshaft holder 23 integrally formed on the upper surface of the cylinder head 14 and a rocker shaft holder 25 connected to the upper surface of the cylinder head 14 with a bolt 24. An intake rocker arm 28 pivotally supported by an intake rocker shaft 27 fixed to the rocker shaft holder 25 is pressed against the side surface of the rocker shaft holder 25 by a coil spring 29 supported on the outer periphery of the intake rocker shaft 27. Positioned in the direction. A roller 30 provided at one end of the intake rocker arm 28 contacts an intake cam 31 provided on the camshaft 26, and an adjustment screw 32 provided at the other end of the intake rocker arm 28 is connected to the upper end of the valve stem 18 b of the intake valve 18. Abut.

  2 and 3, reference numeral 33 denotes an exhaust cam provided on the camshaft 26, reference numeral 34 denotes an exhaust rocker arm, and reference numeral 35 denotes a roller provided on the exhaust rocker arm 34.

  With the above configuration, the intake rocker arm 28 having the roller 30 in contact with the intake cam 31 swings around the intake rocker shaft 27 as the camshaft 26 rotates, so that the valve stem 18b is pressed against the adjustment screw 32. The intake valve 18 is driven to open and close between a minimum valve lift position (fully closed position) shown in FIG. 1 and a maximum valve lift position (fully opened position) shown in FIG.

  A cam phase variable mechanism (not shown) is provided at the shaft end of the camshaft 26 of the present embodiment, and the phase of the camshaft 26 relative to the phase of the crankshaft, that is, the valve timing can be arbitrarily changed. is there.

  As is apparent from FIGS. 2, 3 and 5, the intake rocker arm 28 is made of a non-magnetic material such as aluminum, for example, and is fixed so that a rod-like permanent magnet 36 is partially embedded in one side surface thereof. Is done. The permanent magnet 36 is arranged so that the direction connecting the N pole 36 a and the S pole 36 b at both ends (hereinafter referred to as the axial direction) is along the tangential direction of a circle centering on the axis O of the intake rocker shaft 27. .

  On the other hand, a rocking angle sensor 37 for detecting the rocking angle of the intake rocker arm 28 is fixed to the upper surface of the sensor support portion 25 a protruding from one side of the rocker shaft holder 25 with bolts 38 and 38. The swing angle sensor 37 is provided with a detection element 39 facing the moving path of the permanent magnet 36 and an IC chip 40.

  As is apparent from FIG. 5, when the intake rocker arm 28 swings between the minimum valve lift position (fully closed position) indicated by a solid line and the maximum valve lift position (fully open position) indicated by a chain line, the permanent magnet 36 is It moves substantially in the axial direction between the solid line position and the chain line position with respect to the detection element 39 of the swing angle sensor 37.

  The swing angle sensor 37 is called an MI sensor (magneto-impedance effect sensor), and changes the relative position of the permanent magnet 36 by utilizing the property that the magnetic impedance of the magnetic element changes according to the change of the magnetic field. Can be detected. That is, when the intake rocker arm 28 swings around the intake rocker shaft 27, the magnetic field of the permanent magnet 36 at the position of the detection element 39 of the swing angle sensor 37 changes, so that the swing angle of the intake rocker arm 28, that is, The valve lift of the intake valve 18 can be detected.

  At this time, the moving range of the permanent magnet 36 is symmetrical with respect to a straight line connecting the axis O of the intake rocker shaft 26 and the detection element 39. Further, the length L of the permanent magnet 36 is set to the stroke S so that the N pole 36a and the S pole 36b at both ends of the permanent magnet 36 do not swing to the position where the intake rocker arm 28 swings from the detection element 39. It is set to more than twice.

  The graph of FIG. 6 shows a change in voltage detected and output by the swing angle sensor 37 when the permanent magnet 36 is moved in the axial direction (direction connecting the N pole 36a and the S pole 36b) with respect to the detection element 39. Is shown. In the region indicated by A in this graph, the output of the swing angle sensor 37 changes linearly, and therefore the output and the swing angle of the intake rocker arm 28 can be associated with each other uniquely and accurately. In order to perform detection in the region A, the length L of the permanent magnet 36 is set to L ≧ 2S with respect to the axial stroke S of the permanent magnet 36 accompanying the swing of the intake rocker arm 28 as described above. Is desirable. However, since it is meaningless to increase the length L of the permanent magnet 36 indefinitely, it is desirable that L is slightly larger than 2S.

  In order to increase the detection accuracy of the swing angle sensor 37, it is desirable to move the permanent magnet 36 in the axial direction. However, since the intake rocker arm 28 swings, strictly speaking, the permanent magnet 36 also swings. Will exercise. However, since the swing angle of the intake rocker arm 28 is small, it can be considered that the permanent magnet 36 moves substantially in the axial direction, and the influence on the detection accuracy can be ignored.

  As described above, since the change of the magnetic field accompanying the movement of the permanent magnet 36 provided on the intake rocker arm 28 is detected by the detection element 39 of the swing angle sensor 37, the swing of the intake rocker arm 28 is detected from the detected change of the magnetic field. The angle can be known with high accuracy, and the valve lift of the intake valve 18 having a one-to-one correspondence with the swing angle of the intake rocker arm 28 can be detected continuously and with high accuracy.

  Further, since the intake rocker arm 28 to which the permanent magnet 36 is attached is made of nonmagnetic aluminum, the magnetic field of the permanent magnet 36 is prevented from escaping to the intake rocker arm 28 side, and the detection accuracy of the swing angle sensor 37 is improved. be able to.

  Further, since the rocking angle sensor 37 is provided in the rocker shaft holder 25 that supports the intake rocker shaft 27, the distance from the axis O of the intake rocker arm 28 to the rocking angle sensor 37 is shortened, and the length of the permanent magnet 36 is increased. Can be minimized. This is because, in order to obtain the characteristics of the region A in the graph of FIG. 6, the length L of the permanent magnet 36 needs to be set to be twice or more of the stroke S. This is because if the distance to the moving angle sensor 37 is shortened, the stroke S of the permanent magnet 36 facing the detection element 39 is shortened, and the length L of the permanent magnet 36 can be shortened.

  In particular, since the swing angle sensor 37 is attached to the upper surface of the rocker shaft holder 25, that is, above the cylinder axis direction, the swing angle sensor 37 is exposed by simply removing the head cover from the cylinder head 14, and it is easy to attach and detach and maintain it. become.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the first embodiment, the intake rocker arm 28 is made of a non-magnetic material such as aluminum. In the second embodiment, the intake rocker arm 28 is made of a magnetic material such as cheap iron. Yes. In this case, there is a problem that the magnetic field generated by the permanent magnet 36 escapes to the intake rocker arm 28 and the detection accuracy of the swing angle sensor 37 decreases. Therefore, in the second embodiment, a nonmagnetic body 41 (for example, synthetic resin) is embedded in a part of the intake rocker arm 28, and a permanent magnet 36 is attached to the nonmagnetic body 41.

  Therefore, also according to the second embodiment, it is possible to achieve the same function and effect as those of the first embodiment.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, although the MI sensor is used for the detection element 39 in the embodiment, an MR sensor or a Hall element can be used.

  In the embodiment, the valve lift of the intake valve 18 is detected, but the valve lift of the exhaust valve can be detected with the same structure.

  Further, the structure of the valve operating mechanism of the engine to which the present invention is applied is arbitrary, and any structure can be used as long as the valve lift including the valve timing can be changed regardless of whether it is stepped or continuously.

  In order to increase the detection accuracy, it is desirable that the moving direction of the permanent magnet 36 is exactly the same as the axial direction connecting the N pole 36a and the S pole 36b, but the moving direction of the permanent magnet 36 is relative to the axial direction. Even if it has a slight angle, there is no problem, and such a case is included in the scope of rights of the present invention.

The figure which shows the valve operating mechanism of the intake valve of the engine which concerns on 1st Embodiment (valve closed state) 2-2 line view of FIG. 3-3 line view of FIG. Action explanatory diagram corresponding to FIG. 1 (valve open state) The figure which shows the positional relationship of the detection element of a rocking angle sensor, and a permanent magnet Graph showing the relationship between the output of the swing angle sensor and the displacement of the permanent magnet The figure corresponding to the said FIG. 2 which concerns on 2nd Embodiment The figure corresponding to the said FIG. 3 which concerns on 2nd Embodiment.

Explanation of symbols

25 Rocker shaft holder (swing support part)
28 Intake rocker arm (valve drive member)
36 Permanent magnet 36a N pole 36b S pole 37 Oscillation angle sensor (sensor)
41 Non-magnetic material

Claims (6)

In the valve lift detection device for detecting the valve lift of the engine based on the amount of movement of the valve drive member (28),
Permanent magnets (36) such that the N pole (36a) and the S pole (36b) are arranged along the moving direction of the valve driving member (28) on the valve driving member (28) made of a non-magnetic material. And a change in the magnetic field is detected by a sensor (37) arranged so as to face the side of the movement path of the permanent magnet (36). Based on the change in the magnetic field, the valve drive member (28) A valve lift detection device characterized by detecting a movement amount.   The valve lift according to claim 1, characterized in that the valve drive member is a rocker arm (28) and the sensor (37) is attached to a rocking support (25) of the rocker arm (28). Detection device.   The valve lift detection device according to claim 2, wherein the sensor (37) is mounted above the swing support portion (25) in the cylinder axial direction. In the valve lift detection device for detecting the valve lift of the engine based on the amount of movement of the valve drive member (28),
A non-magnetic body (41) is attached to the valve drive member (28) made of a magnetic material, and an N pole (36a) and an S pole (36b) are arranged along the moving direction of the valve drive member (28). A permanent magnet (36) is attached to the non-magnetic body (41) as described above, and a change in the magnetic field is detected by a sensor (37) arranged to face the side of the movement path of the permanent magnet (36), A valve lift detection device that detects the amount of movement of the valve drive member (28) based on the change of the magnetic field.   The valve lift according to claim 4, characterized in that the valve drive member is a rocker arm (28) and the sensor (37) is attached to a rocking support (25) of the rocker arm (28). Detection device.   6. The valve lift detection device according to claim 5, wherein the sensor (37) is mounted above the swing support part (25) in the cylinder axial direction.

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