JP4865670B2 - Variable valve opening characteristics valve gear - Google Patents

Description

  The present invention relates to a valve opening characteristic variable valve operating device that can change valve opening characteristics such as a lift amount of a valve in accordance with an operation state.

  In recent years, an increasing number of internal combustion engines such as gasoline engines and diesel engines are equipped with various valve opening characteristics variable valve operating devices in order to improve output and fuel consumption, reduce harmful exhaust gas components, and the like. As this type of valve opening characteristics variable type valve operating device, there is a conventional one that switches between a low speed type cam and a high speed type cam according to the operating condition, but in recent years, further improvement of transient characteristics and reduction of throttle etc. have been realized. In order to achieve this, there has been a continuous change in valve opening characteristics (valve lift and valve timing).

In this type of variable valve opening characteristic type valve operating apparatus, a control member that changes the valve opening characteristic is driven by an actuator having a drive source such as an electric motor. A position sensor for detecting the position of the control member is provided in addition to the speed reduction mechanism for decelerating and transmitting the driving force to the control member (see Patent Document 1).
JP 2007-16726 A

  However, the contact position sensor is provided with a return spring for returning the detection member engaged with the detection target to the initial position, and the urging force of the return spring causes the detection member on the sensor side and the detection member on the detection target side. By holding the member in contact with each other, the position of the detection target can be accurately detected in conjunction with each other.

  However, if the return spring built in the position sensor is subject to sag due to aging (permanent distortion), the function of holding the sensor-side detection member and the detection-side member in contact with each other decreases, and the position The detection accuracy of the sensor may decrease.

  In addition, mechanical backlash generated in the structural member of the valve operating device and the structural member of the motion transmission mechanism that transmits the motion of the control member to the position sensor can be absorbed by the biasing force of the spring. If the mechanical play increases, it is not possible to cope with the urging force of the spring in the position sensor alone, and it is predicted that the detection accuracy of the position sensor will decrease.

  The present invention has been devised based on such inventor's knowledge, and the main object of the present invention is configured to suppress a decrease in detection accuracy of the position sensor due to secular change. Another object of the present invention is to provide a variable valve opening device.

In order to solve such a problem, in the variable valve opening characteristic type valve operating apparatus according to the present invention, as shown in claim 1, a control member for changing the valve opening characteristic of the valve (2) for performing intake or exhaust ( The control shaft 20, the gear link 21, and the roller link 22), a drive source (electric motor 41) for driving the control member, a position sensor (43) for detecting the position of the control member, and the movement of the control member. Motion transmitting means (sensor detection gears 61 to 63) for transmitting the motion sensor to the position sensor, and a housing (47) for housing the motion transmitting means. The position sensor is initially provided with the detection member (65). with a first spring for returning to the position (103) is built, the other end the housing with one end detection member of the position sensor is engaged Is fixed to the second spring biasing the sensing member of the position sensor away can abut each other in the motion transmission means side of the sensor engagement member (66) in a direction to be pressed against the sensor engagement member (101) was provided.

According to this, the detection member on the sensor side is provided by the second spring interposed between the detection member on the sensor side and the housing, regardless of the sag of the first spring ( return spring ) built in the sensor. And the sensor engagement member on the motion transmission means side are held in contact with each other, and a sufficiently large biasing force by the second spring is applied to the sensor engagement member on the motion transmission means side via the detection member on the sensor side. Since the backlash of these constituent members is absorbed by acting on the constituent members of the motion transmission means and the valve gear, the deterioration of the detection accuracy due to secular change can be suppressed.

Further, by appropriately setting the spring characteristic of the second spring interposed between the detection member on the sensor side and the housing, the load torque fluctuation can be changed without changing the first spring built in the sensor. Therefore, it is possible to realize an optimal spring characteristic corresponding to the above, and to reliably hold the detection member on the sensor side and the sensor engagement member on the motion transmission means side in contact with each other, thereby improving the detection accuracy. .

In the valve opening characteristic variable valve operating apparatus, as shown in claim 2, the second spring is a torsion coil spring, and the coil portion (101a) is a sensor engaging member on the motion transmission means side. It can be set as the structure provided coaxially so that the circumference | surroundings may be surrounded.

According to this, since the second spring can be disposed in the gap between the sensor engagement member and the housing, an increase in the size of the housing can be avoided. Moreover, since it is arranged on the outer periphery of the sensor engaging member, it becomes a large-diameter torsion coil spring, a large spring load can be obtained, and a large rotation angle can be accommodated.

Thus, according to the present invention, the second spring interposed between the detection member on the sensor side and the housing, regardless of the sag of the first spring ( return spring ) built in the sensor, The detection member on the sensor side and the sensor engagement member on the movement transmission means side are held in contact with each other, and a sufficiently large biasing force by the second spring is applied to the movement transmission means side via the detection member on the sensor side. Since the backlash of these components is absorbed by acting on the sensor engagement member of this, and further acting on the component of the motion transmission means and the valve operating device, the deterioration of detection accuracy due to secular change is suppressed. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an upper portion of an engine according to the present invention. FIG. 2 is a perspective view showing the variable valve opening characteristic valve operating device for the engine shown in FIG. FIG. 3 is a longitudinal sectional view showing an operation state of the valve opening characteristic variable valve operating apparatus shown in FIG.

  As shown in FIG. 1, this engine is an in-line four-cylinder engine mounted on an automobile. The cylinder head 1 includes two exhaust valves 2 for each cylinder 5, As a valve operating mechanism for driving, a camshaft 4 provided with a cam 3, a rocker arm 6 interposed between the valve 2 and the cam 3, and a valve spring 7 for constantly urging the valve 2 in the closing direction are provided. Yes.

  On the intake side, two intake valves 8 are provided for each cylinder, and a camshaft, a rocker arm, and a valve spring (not shown) are provided as valve gears for driving the valves. ing.

  The cam shaft 4 is rotatably supported by the cam holder 11. The cam holder 11 is provided so as to partition the valve operating chamber 10 for each cylinder 5 and is fastened and fixed to the upper surface of the cylinder head 1 with bolts.

  This engine is equipped with a valve opening characteristic variable valve operating device that variably controls the lift amount of the exhaust valve 2. This variable valve opening characteristic type valve operating apparatus has an actuator 14 installed on the upper surface of a base plate 13 provided so as to cover the upper side of the valve operating chamber 10 and a link mechanism driven by the actuator 14. Yes. It is also possible to apply a valve opening characteristic variable valve operating device having a similar mechanism to the intake valve 8.

  As shown in FIG. 2, the link mechanism of the variable valve opening characteristic valve operating device is supported by a control shaft (control member) 20 extending in the lateral direction and a cam holder 11 so as to be rotatable, and the control shaft 20 A gear link (control member) 21 that is rotatably held, and a roller link (control member) 22 that is swingably held by the control shaft 20 and that has a free end interposed between the cam 3 and the rocker arm 6. have.

  The roller link 22 is provided for each cylinder, and operates in conjunction with the turning of the control shaft 20 accompanying the rotation of the gear link 21, and the valve 2 according to the displacement of the swing fulcrum of the roller link 22 caused thereby. The lift amount is changed. The control shaft 20 is rotatably supported by the cam holder 11 via the link holder 30. The rotation center lines of the gear link 21 and the roller link 22 are parallel to each other.

  The gear link 21 extends in an arc shape in the circumferential direction from the free end side of the arm portion 24 that rotates around the support shaft 23 provided in the cam holder 11, and serves as a gear on the actuator 14 side. The gear portion 25 is engaged with the gear portion 25 and is rotated by the driving force of the actuator 14. A shaft holder 26 is formed on the free end side of the arm portion 24 to hold the control shaft 20 in a rotatable manner.

  The roller link 22 has a base portion 28 that is fitted to the control shaft 20 and serves as a rocking fulcrum, and a pair of arm portions 29 extending from the base portion 28. At the tip of the arm portion 29, there are a roller 31 that is in rolling contact with the cam 3 of the camshaft 4, and a roller shaft 32 that is in contact with the slipper surface of the rocker arm 6.

  The rocker arm 6 includes a base portion 35 rotatably supported by a rocker shaft 34 held by the cam holder 11, and a pair of arm portions 36 extending from the base portion 35, and the pair of arms As shown in FIG. 3, each of the portions 36 is provided with a tip portion 38 that presses the stem end 37 of the valve 2 and an adjustment screw 39 that adjusts its position.

  In the valve opening characteristic variable valve operating apparatus configured as described above, the gear link 21 becomes a swing fulcrum of the roller link 22 as it rotates about the support shaft 23 (see FIG. 2). When the control shaft 20 is displaced, the lift amount of the valve 2 changes, and the lift amount of the valve 2 can be adjusted steplessly according to the rotation angle position (link angle) of the gear link 21.

  When reducing the valve lift during idling or the like, the gear link 21 is set to the minimum lift position (for example, link angle = 0 degree) shown in FIG. 3A, and in this case, it becomes the swing fulcrum of the roller link 22. Even if the control shaft 20 is positioned above the rocker arm 6 and the roller 31 is pushed down by the cam 3, the roller shaft 32 rolls along the slipper surface 33 as indicated by the arrow, so that the rocker arm 6 swings. (That is, the lift amount of the valve 2) is reduced.

  On the other hand, when increasing the valve lift during high load operation or the like, the gear link 21 is set to the maximum lift position (for example, link angle = 60 degrees) shown in FIG. 3B, and in this case, the roller link 22 is swung. When the control shaft 20 serving as a fulcrum is located on the side of the rocker arm 6 and the roller 31 is pushed down by the cam 3, the roller shaft 32 hardly rolls along the slipper surface 33. The amount increases.

  4 is a cross-sectional view of a main part of the actuator 14 shown in FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. FIG. 7 is an exploded perspective view of a main part of the actuator 14 shown in FIG. FIG. 8 is a schematic perspective view for explaining the action of the spring shown in FIG.

  As shown in FIG. 4, the actuator 14 includes an electric motor (drive source) 41 that drives the gear link 21, a link drive gear mechanism 42 that transmits the movement of the electric motor 41 to the gear link 21, and the gear link 21. A position sensor 43 (see FIG. 1) for detecting the angular position (link angle) of the gear link 21 and a sensor detection gear mechanism 44 for transmitting the movement of the gear link 21 to the position sensor 43.

  The electric motor 41 is a brushless motor. In the engine ECU, the target lift amount of the valve 2 set based on various operation information such as the depression amount of the throttle pedal and the coolant temperature by the driver, that is, the rotation of the gear link 21. The drive current of the electric motor 41 is controlled so that the detection position of the position sensor 43 coincides with the moving angle position (link angle).

  As shown in FIG. 5, the link driving gear mechanism 42 includes a first gear 51 provided on the output shaft 45 of the electric motor 41, a second gear 52 that meshes with the first gear 51, and the second gear 52. The gear 52 has a third gear 53 provided coaxially and relatively non-rotatably. The third gear 53 meshes with the gear link 21, so that the driving force of the electric motor 41 is in two stages. It is decelerated and transmitted to the gear link 21.

  The second gear 52 and the third gear 53 for link driving are connected by a shaft 55, and the shaft 55 is supported by the housing 47 via bearings 56 and 57.

  As shown in FIG. 6, the sensor detection gear mechanism 44 includes a first gear 61 that meshes with the gear link 21, a second gear 62 that is provided coaxially with the first gear 61 and is relatively non-rotatable, A third gear 63 that meshes with the second gear 62 is provided, and the sensor engagement member 66 that engages with the detection member 65 of the position sensor 43 rotates integrally with the third gear 63. Thus, the angular position (link angle) of the gear link 21 is detected by the position sensor 43.

  The position sensor 43 is a so-called Hall sensor, and a Hall element, a permanent magnet, a control board, and the like for detecting the rotation of the detection member 65 are accommodated in the housing.

  The first gear 61 and the second gear 62 for sensor detection are connected by a shaft 68, and the shaft 55 is supported by the housing 47 via a bearing 69. The sensor detection third gear 63 is connected to one end of the shaft 71, and the sensor engaging member 66 is connected to the other end of the shaft 71. The shaft 71 is connected to the housing 47 via a bearing 72. It is supported.

In the housing 47, the empty chamber 86 of the detecting member 65 and the sensor engagement member 66 of the position sensor 43 is accommodated, a spring for urging in a direction for pressing the sensing member 65 of the position sensor 43 to the sensor engaging member 66 ( (Second spring) 101 is provided.

  This spring 101 is a torsion coil spring, and its coil portion 101 a is provided coaxially so as to surround the periphery of the sensor engagement member 66, and its one end 101 b engages with the detection member 65 of the position sensor 43. The other end 101 c is fixed to the housing 47. Specifically, a locking hole 102 is formed in the detection member 65 in the axial direction, and one end 101b of the spring 101 is inserted and locked therein. A locking hole 103 is formed in the housing 47 in the axial direction, and the other end 101c of the spring 101 is inserted and locked therein.

  As shown in FIG. 7, the sensor engaging member 66 is provided with a pair of protrusions 111 protruding in the axial direction. On the other hand, the detection member 65 of the position sensor 43 has a pair of contact portions 112 that contact the protrusion 111 of the sensor engagement member 66 in the circumferential direction, and are in contact with each other by a unidirectional rotational force. However, when a rotational force in the other direction is applied, they are separated from each other and do not rotate together.

  The position sensor 43 is assembled in the axial direction with respect to the housing 47, and the detection member 65 of the position sensor 43 enters a position where it can engage with the protrusion 111 of the sensor engagement member 66. At this time, one end 101b and the other end 101c of the spring 101 are inserted into the locking hole 102 of the detection member 65 and the locking hole 103 of the housing 47, and the spring 101 is bent so as to obtain an initial load as required. Incorporate in the state.

As shown in FIG. 8, the spring 101 biases the detection member 65 in the same direction as the return spring (first spring) 103 built in the position sensor 43 in order to return the detection member 65 to the initial position. . For this reason, the detection member 65 of the position sensor 43 and the sensor engagement member 66 are held in contact with each other by the spring 101 regardless of the sag of the return spring 103.

  Further, a sufficiently large urging force by the spring 101 acts on the sensor engagement member 66 via the detection member 65 of the position sensor 43, and the sensor detection third gear 63 connected to the sensor engagement member 66. From the second gear 62, the first gear 61, the gear link 21, and the control shaft 20 to the roller link 22, the backlash of the motion transmission system is absorbed, and the motion transmission system It is possible to avoid the deterioration of the detection accuracy of the position sensor 43 due to the backlash.

  In addition, a phenomenon in which the detection member 65 of the position sensor 43 and the sensor engagement member 66 come into contact with or separate from each other due to vibration transmitted from the valve operating device to the sensor engagement member 66 mainly due to the opening / closing operation of the valve 2 occurs. Then, by setting the spring characteristics of the spring system including the spring 101 and the return spring 103 built in the position sensor 43 so as to correspond to the load torque fluctuation at this time, the detection member 65 of the position sensor 43 and the sensor relationship are set. The detection accuracy of the position sensor 43 can be increased by reliably holding the joint member 66 in a contact state.

It is a perspective view which shows the upper part of the engine by this invention. It is a perspective view which shows the valve opening characteristic variable type valve operating apparatus of the engine shown in FIG. FIG. 3 is a longitudinal sectional view showing an operation state of the valve opening characteristic variable valve operating apparatus shown in FIG. 2. It is principal part sectional drawing of the actuator shown in FIG. It is sectional drawing cut | disconnected by the VV line | wire of FIG. It is sectional drawing cut | disconnected by the VI-VI line of FIG. It is a principal part disassembled perspective view of the actuator shown in FIG. It is a typical perspective view explaining the effect | action of the spring shown in FIG.

Explanation of symbols

2 Valve 14 Actuator 20 Control shaft (control member)
21 Gear link (control member)
22 Roller link (control member)
41 Electric motor (drive source)
42 Link Drive Gear Mechanism 43 Position Sensor 44 Sensor Detection Gear Mechanism 47 Housing 51-53 Link Drive Gears 61-63 Sensor Detection Gear (Motion Transmission Means)
65 Detection member 66 Sensor engagement member 86 Vacant chamber 101 Spring, 101a Coil portion, 101b One end, 101c Other end 102/103 Locking hole

Claims (2)

A control member that changes the valve opening characteristics of a valve that performs intake or exhaust, a drive source that drives the control member, a position sensor that detects the position of the control member, and a motion of the control member that is transmitted to the position sensor A motion transmission means for carrying out the operation and a housing for accommodating the motion transmission means,
The position sensor incorporates a first spring for returning the detection member to the initial position,
Is fixed to the other end the housing with one end detection member of the position sensor is engaged, the detection member of the position sensor in which the mutually separated can abut the sensor engagement member motion transmission means side A valve opening characteristic variable valve operating device, characterized in that a second spring is provided for urging in a direction in which the sensor engaging member is pressed against the sensor engaging member . The said 2nd spring is a torsion coil spring, The coil part was provided coaxially so that the circumference | surroundings of the sensor engagement member by the side of the said motion transmission means might be surrounded. Valve opening characteristics variable type valve gear.

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