JP2017219018A - Valve train mechanism of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve train mechanism of an internal combustion engine capable of suppressing valve jump.SOLUTION: A valve train mechanism 15 of an internal combustion engine 1 includes: a bottomed receiving hole 19 formed on a cylinder head 3; a hydraulic lash adjuster 17 received in the receiving hole so as to move within a predetermined range; a rocker arm 18 supported at a tip end portion of the lash adjuster; a valve 10; a first oil chamber 40 which is defined by cooperation between a bottom portion of the receiving hole and a base end portion of the lash adjuster; a supply oil path 41 which connects an oil path 25 and the first oil chamber; a discharging oil path 42 which connects the first oil chamber and an outer surface of the cylinder head; a first valve 43 which is provided in the supply oil path, prevents a flow from the first oil chamber to the oil path, and permits a flow in the opposite direction; and a second valve 44 which is provided in the discharging oil path, and permits a flow from the first oil chamber side to the outer surface side of the cylinder heads when pressure on the first oil chamber side becomes larger than pressure on the outer surface side of the cylinder head by a predetermined value or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a valve mechanism for an internal combustion engine.

  As a valve operating mechanism for an internal combustion engine, a camshaft that rotates in synchronization with a crankshaft, a rocker arm that is rotatably supported by a rocker shaft or a lash adjuster, and is closed by a valve spring and closed by a valve spring A configuration having an intake valve and an exhaust valve that are urged in the direction and opened by being pushed in a valve opening direction at a predetermined timing by a rocker arm is known. In such a valve operating mechanism, the load applied from the camshaft to the rocker arm increases as the rotational speed of the internal combustion engine increases. Therefore, in an overspeed range exceeding the maximum allowable rotational speed of the internal combustion engine, the rocker arm becomes difficult to follow the rotation of the camshaft due to the inertial force and is separated from the camshaft, so that the valve lift amount becomes larger than the appropriate value. Valve jump may occur. In situations where valve jumps occur, the range of movement of the rocker arm and valve increases, so it is necessary to secure a wide sliding contact area between each member and to increase the rigidity of each member. There is a problem of becoming. As a technique for preventing such valve jump, it is conceivable to increase the spring constant of the valve spring and urge the rocker arm more strongly toward the camshaft side. However, in this case, the energy required for opening the valve increases, and the fuel consumption deteriorates.

  Instead of increasing the spring constant of the valve spring, a regulating member is placed inside the valve spring, and the moving range of the spring retainer is regulated to a predetermined range by the regulating member, and the moving range of the valve and rocker arm is regulated. (For example, Patent Document 1).

Japanese Utility Model Publication No. 2-144605

  In the invention according to Patent Document 1, since the restricting member is arranged in a narrow space inside the valve spring, there are many restrictions on the size, shape, rigidity, and the like of the restricting member. Therefore, there is a demand for a valve jump restricting means with relatively few restrictions and high versatility. Further, in the invention according to Patent Document 1, since the movement range of the valve and the rocker arm is regulated by regulating the movement range of the spring retainer, an excessive load in the over-rotation region is transmitted to the valve and the spring retainer. Therefore, the valve and the spring retainer are required to have relatively high rigidity.

  In view of the above background, it is an object of the present invention to provide a valve mechanism for an internal combustion engine that can suppress valve jump.

  In order to solve the above problems, one aspect of the present invention is a valve operating mechanism (15, 50, 70) of an internal combustion engine (1), which has a bottomed receiving hole (19) formed in a cylinder head (3). ), A hydraulic lash adjuster (17) whose base end is received in the receiving hole so as to be movable within a predetermined range in the axial direction of the receiving hole, and a tip of the lash adjuster protruding from the receiving hole A rocker arm (18) that is pivotally supported and driven by a camshaft (16), a valve (10) that is provided in the cylinder head and that is opened by being pushed by the rocker arm, and the receiving hole A first oil chamber (40) that is defined in cooperation with a bottom portion and a base end portion of the lash adjuster, and whose volume is increased or decreased by movement of the lash adjuster with respect to the receiving hole; and the cylinder head A supply oil passage (41) connecting the oil passage (25) formed to the first oil chamber, a discharge oil passage (42) connecting the first oil chamber and the outer surface of the cylinder head, A first valve (43) provided in the supply oil passage and blocking oil flow from the first oil chamber to the oil passage while allowing reverse oil flow; and provided in the discharge oil passage. While preventing the flow of oil from the outer surface of the cylinder head to the first oil chamber, the pressure on the first oil chamber side in the exhaust oil passage is a predetermined value or more than the pressure on the outer surface side of the cylinder head. And a second valve (44, 59) for allowing a flow from the first oil chamber side to the outer surface side of the cylinder head when it becomes larger.

  According to this aspect, when the load applied to the rocker arm from the camshaft increases during the overspeed of the internal combustion engine, the pressure in the first oil chamber rises, the second valve opens, and the oil in the first oil chamber is discharged to the discharged oil. It passes through the road and is discharged outside. As a result, the lash adjuster moves to the bottom side of the receiving hole, and the pivot center of the rocker arm moves in a direction away from the camshaft, thereby reducing the amount by which the rocker arm pushes down the valve. Thereby, an increase in the lift amount of the valve at the time of excessive rotation of the internal combustion engine is suppressed. Further, since the load applied to the valve from the rocker arm is reduced, the rigidity required for the valve is lowered.

  In the above aspect, the bottomed stopper receiving hole (52) that forms part of the oil discharge passage and opens on the outer surface of the cylinder head, and the stopper receiving hole are movably received within a predetermined range. A stopper (51) and a second oil chamber (57) in which the bottom of the stopper receiving hole (52) and the base end of the stopper are defined in cooperation, and the volume is increased or decreased by the movement of the stopper. And the stopper is positioned in a direction opposite to the rocker arm with respect to the first position, and a first position where the rocker arm contacts the rocker arm when the rocker arm is in a predetermined limit position away from the camshaft. It is good to be movable between the second positions.

  According to this aspect, when the lash adjuster is immersed in the receiving hole at the time of excessive rotation of the internal combustion engine, the oil in the first oil chamber is supplied to the second oil chamber, and the stopper is maintained at the first position. As a result, the rocker arm is restricted to a predetermined limit position by the stopper, and the load transmitted from the rocker arm to the valve is reduced. Further, when the rocker arm pushes the stopper, the oil in the second oil chamber buffers the movement of the stopper.

  In the above aspect, it is preferable that the stopper extends in a tangential direction around the rotation center of the rocker arm when the rocker arm is in the limit position.

  According to this aspect, the stopper abuts against the rocker arm from the front with respect to the movement direction of the rocker arm, and the movement of the rocker arm is reliably restricted.

  In the above aspect, the rocker arm includes an arm main body (18A) rotatably provided on the cylinder head, and a roller (18B) rotatably supported by the arm main body and contacting the camshaft. The stopper may be in contact with the roller when the rocker arm is in the limit position.

  According to this aspect, since the rocker arm comes into contact with the stopper in the roller having relatively high rigidity, deformation is suppressed.

  In the above aspect, a biasing device (58) for biasing the stopper toward the first position is provided between the cylinder head and the stopper, and the biasing device is a spring member. , And at least one of the opposing magnet pairs.

  According to this aspect, when the stopper is pushed down by the rocker arm, the time required for the stopper to return to the first position by the urging force of the urging device is shortened.

  In the above aspect, the stopper may have an injection hole (71) extending from a proximal end portion facing the second oil chamber to a distal end portion facing the rocker arm.

  According to this aspect, oil is supplied to the abutting portion between the stopper and the rocker arm, and the impact when the stopper and the rocker arm abut is buffered.

  In the above aspect, the opening end at the tip of the injection hole may be provided on the rocker arm and face a portion of the roller that contacts the camshaft on the side opposite to the camshaft.

  According to this aspect, since the oil is supplied to the lower surface side of the roller, the amount of oil entrapped in the sliding contact portion between the roller and the camshaft is suppressed compared to the case where the oil is supplied to the upper surface side of the roller. Thus, the frictional resistance of the roller and the camshaft is reduced.

  In the above aspect, the roller may be rotated toward the valve side on the side facing the stopper by contacting the camshaft.

  According to this aspect, the oil supplied to the surface of the roller is scattered toward the sliding contact portion between the rocker arm and the valve by the rotation of the roller, and the sliding contact portion between the rocker arm and the valve is lubricated.

  In the above aspect, the second valve may be a valve that opens when a difference in pressure acting on both ends is equal to or greater than a predetermined value.

  According to this aspect, the structure of the second valve can be simplified.

  In the above aspect, the second valve may be an electromagnetic valve that is controlled to open and close based on a signal from a control device.

  According to this aspect, since the opening / closing timing of the second valve can be arbitrarily controlled, it is possible to control the timing and amount of movement of the lash adjuster. Thereby, it becomes possible to appropriately control the behavior of the rocker arm and the valve at the time of excessive rotation.

  In the above aspect, the second valve may be controlled to open and close based on the number of rotations of the crankshaft.

  According to this aspect, the second valve can be controlled by appropriately determining when the internal combustion engine is over-rotating.

  According to the above structure, the valve operating mechanism of the internal combustion engine which can suppress a valve jump can be provided.

Sectional drawing in the valve closing state of the valve operating mechanism which concerns on 1st Embodiment Cross section of lash adjuster Sectional drawing in the valve opening state at the time of normal rotation of the valve mechanism which concerns on 1st Embodiment Sectional drawing in the valve opening state at the time of the overspeed of the valve operating mechanism which concerns on 1st Embodiment Sectional drawing in the valve closing state of the valve operating mechanism which concerns on 2nd Embodiment Sectional drawing in the valve closing state of the valve operating mechanism which concerns on 3rd Embodiment It is a schematic diagram of the 2nd valve of the valve operating mechanism which concerns on 3rd Embodiment, Comprising: (A) A valve closing state and (B) a valve opening state are shown. It is a table | surface which shows operation | movement of each structure of a valve operating mechanism, Comprising: (A) Operation | movement at the time of the overspeed of the valve operating mechanism which concerns on 2nd Embodiment and 3rd Embodiment, (B) of the valve operating mechanism which concerns on a comparative example Indicates operation during overspeed The graph which shows the valve lift at the time of normal time and overspeed of the valve mechanism based on 2nd Embodiment and 3rd Embodiment, and the valve mechanism which concerns on a comparative example Sectional drawing in the valve closing state of the valve operating mechanism which concerns on 4th Embodiment

  Embodiments of a valve operating mechanism for an internal combustion engine according to the present invention will be described below with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 3 coupled to the upper end surface of the cylinder block 2, and an upper surface 3 </ b> A of the cylinder head 3. A head cover 5 defining a chamber 4. The cylinder block 2 is formed with a cylinder 6 opened at the upper end surface. A piston (not shown) is accommodated in the cylinder 6 so as to be able to reciprocate. The lower surface of the cylinder head 3 closes the upper end of the cylinder 6 and defines the combustion chamber 7 in cooperation with the wall surface of the cylinder 6 and the crown surface of the piston.

  The cylinder head 3 is formed with an intake port 8 and an exhaust port (not shown) extending from the combustion chamber 7 to the side surface of the cylinder head 3. The opening end of the intake port 8 on the combustion chamber 7 side is opened and closed by a valve 10 that is a poppet valve. The valve 10 includes an axial stem portion 10A and a disc-shaped umbrella portion 10B coupled to the lower end of the stem portion 10A. The stem portion 10 </ b> A is inserted into a cylindrical valve guide 11 that penetrates from the intake port 8 to the upper surface 3 </ b> A of the cylinder head 3. As a result, the valve 10 is moved along the valve guide 11 so that the umbrella portion 10B closes the opening end of the intake port 8 on the combustion chamber 7 side, and the umbrella portion 10B moves to the combustion chamber 7 side so that the intake port It is possible to move between the open position where 8 is opened. A disc-shaped spring retainer 12 is coupled to the end of the stem portion 10A on the valve operating chamber 4 side. A valve spring 13 is interposed between the spring retainer 12 and the upper surface 3 </ b> A of the cylinder head 3. The valve 10 is biased toward the valve closing position by the valve spring 13. A stem seal 14 that seals the gap with the stem portion 10A is provided at the end of the valve guide 11 on the valve operating chamber 4 side. The configuration of the exhaust port and the valve 10 that opens and closes the exhaust port is the same as the configuration of the intake port 8 and the valve 10.

  The intake port 8 and the exhaust port valve 10 are opened and closed by a valve operating mechanism 15. The valve mechanism 15 according to the present embodiment is a DOHC type, and the configuration corresponding to the intake port 8 and the portion corresponding to the exhaust port are the same, so the valve mechanism that opens and closes the valve 10 of the intake port 8. The 15 intake side portions will be described below.

  The intake side portion of the valve mechanism 15 includes a camshaft 16 and a rocker arm 18 provided on the cylinder head 3 via a hydraulic lash adjuster (HLA) 17. The camshaft 16 is rotatably supported by a bearing (not shown) provided in the cylinder head 3. The camshaft 16 is connected to the crankshaft by a chain transmission mechanism (not shown) including a chain and a sprocket, and rotates at a rotational speed that is 1/2 that of the crankshaft in synchronization with the crankshaft. The camshaft 16 has a cam 16A that is a disc cam protruding in the radial direction.

  The upper surface 3A of the cylinder head 3 is formed with an HLA receiving hole 19 that is a bottomed hole having a circular cross section that opens upward. A lash adjuster 17 is slidably inserted into the HLA receiving hole 19.

  As shown in FIG. 2, the lash adjuster 17 is inserted into the HLA receiving hole 19 and has a bottomed cylindrical housing 21 having an open upper end, and a base end portion and the housing 21 slidably received in the housing 21. And a plunger 22 having a tip portion protruding from the outside. An outer peripheral housing oil groove 23 that extends in the circumferential direction and forms an annular shape is formed on the outer peripheral surface of the housing 21. The outer peripheral housing oil groove 23 is connected to a head oil passage 25 formed in the cylinder head 3. The head oil passage 25 is connected to an oil pump through an oil passage formed in the cylinder block 2 and is supplied with high-pressure oil. The housing 21 is formed with a housing oil passage 26 that penetrates in the radial direction from the bottom of the outer peripheral housing oil groove 23 and opens to the inner peripheral surface of the housing 21. On the inner peripheral surface of the housing 21, a portion where the housing oil passage 26 is opened is formed with an inner peripheral housing oil groove 27 that is recessed radially outward and extends in the circumferential direction.

  A plunger oil groove 28 that extends in the circumferential direction and forms an annular shape is formed on the outer peripheral surface of the plunger 22. The plunger oil groove 28 is connected to the inner peripheral housing oil groove 27. A C-shaped retaining ring 29 is attached to the plunger oil groove 28. The outer peripheral portion of the retaining ring 29 protrudes into the inner peripheral housing oil groove 27. The retaining ring 29 abuts against the end portions of the plunger oil groove 28 and the inner peripheral housing oil groove 27 in the axial direction, so that the connection with the plunger oil groove 28 and the inner peripheral housing oil groove 27 can be maintained with respect to the housing 21. The movement range of the plunger 22 is restricted. A reservoir chamber 30 extending in the axial direction is formed inside the plunger 22. The reservoir chamber 30 has a side hole 32 opened at the bottom of the plunger oil groove 28, a distal end hole 33 opened at the outer surface of the distal end, and a proximal end hole 34 opened at the outer surface of the proximal end.

  The bottom of the housing 21 and the bottom of the plunger 22 cooperate with each other to define a pressure chamber 35. The end of the base end hole 34 on the pressure chamber 35 side is closed when the pressure on the pressure chamber 35 side is higher than the pressure on the reservoir chamber 30, and when the pressure on the pressure chamber 35 side is lower than the pressure on the reservoir chamber 30. A check valve 36 is provided that opens to the front. In the pressure chamber 35, a plunger spring 37 that is a compression coil spring is provided between the bottom of the housing 21 and the bottom of the plunger 22. The plunger 22 is urged by the plunger spring 37 in a direction protruding from the housing 21.

  As shown in FIG. 1, the outer peripheral surface of the housing 21 is in sliding contact with the inner peripheral surface of the HLA receiving hole 19. The bottom portion of the HLA receiving hole 19 and the base end portion of the housing 21 cooperate to define a first oil chamber 40. The volume of the first oil chamber 40 increases or decreases as the housing 21 moves in the axial direction with respect to the HLA receiving hole 19. In the first oil chamber 40, a spring 39 is provided between the bottom of the HLA receiving hole 19 and the base end of the housing 21 to bias the housing 21 in a direction in which the housing 21 protrudes from the HLA receiving hole 19. The spring 39 may be a compression coil spring, for example. The cylinder head 3 includes a supply oil passage 41 that connects the first oil chamber 40 (bottom of the HLA receiving hole 19) and the head oil passage 25, a first oil chamber 40 (bottom of the HLA receiving hole 19), and a valve. A discharge oil passage 42 that connects the chamber 4 (the upper surface 3A of the cylinder head 3) is formed.

  The supply oil passage 41 is provided with a first valve 43 that blocks the flow of oil from the first oil chamber 40 to the head oil passage 25 while allowing the reverse flow of oil. Further, the oil discharge path 42 blocks the flow of oil from the upper surface 3 </ b> A of the cylinder head 3 to the first oil chamber 40, while the pressure on the first oil chamber 40 side in the discharge oil path 42 causes the pressure on the upper surface of the cylinder head 3. There is provided a second valve 44 that allows a flow from the first oil chamber 40 side to the upper surface 3A side of the cylinder head 3 when the pressure difference value is greater than a predetermined pressure difference value by 3A side.

  The first valve 43 and the second valve 44 include a valve seat provided in the flow path, a valve body such as a ball that can be seated on the valve seat from one side of the flow path, and a biasing of the valve body toward the valve seat. It may be a known check valve provided with a spring. In this case, by setting the spring constant of the spring to a desired value, the pressure difference between both ends of the valves 43 and 44 when the valve is opened can be set. As will be described in other embodiments described later, the second valve 44 may be an electromagnetic valve that opens and closes in response to a signal from the control device.

  Since the first oil chamber 40 and the head oil passage 25 are connected by the supply oil passage 41 provided with the first valve 43, the hydraulic pressure P1 of the first oil chamber 40 is lower than the hydraulic pressure Ph of the head oil passage 25. Sometimes, oil is supplied from the head oil passage 25 to the first oil chamber 40. Therefore, the hydraulic pressure P1 of the first oil chamber 40 is maintained to be equal to or higher than the hydraulic pressure Ph of the head oil passage 25.

  The second valve 44 is a valve that opens when the difference in pressure acting on both ends is equal to or greater than a predetermined value. Specifically, the second valve 44 is set to open when the hydraulic pressure P1 of the first oil chamber 40 on one end side of the discharge oil passage 42 is equal to or higher than a predetermined value Ps with respect to the hydraulic pressure P2 on the other end side. Has been. In the present embodiment, since the other end side of the discharge oil passage 42 opens to the upper surface 3A of the cylinder head 3, the hydraulic pressure P2 is atmospheric pressure. Therefore, the second valve 44 is opened when the hydraulic pressure P1 on the first oil chamber 40 side is equal to or greater than the value Ps. The value Ps is set larger than a value obtained by adding a predetermined value Pn to the hydraulic pressure Ph of the head oil passage 25. Here, the value Pn is set to the maximum value of the pressure generated in the first oil chamber 40 due to the load applied from the camshaft 16 to the lash adjuster 17 via the rocker arm 18 during normal rotation of the internal combustion engine 1 described later. ing. As a result, the second valve 44 is kept closed during normal rotation of the internal combustion engine. During an overspeed of the internal combustion engine 1 to be described later, the maximum value of the pressure generated in the first oil chamber 40 due to the load applied to the lash adjuster 17 from the camshaft 16 via the rocker arm 18 becomes larger than the value Pn. The oil pressure P1 of the first oil chamber 40 becomes equal to or greater than the value Ps, and the second valve 44 is opened.

  The rocker arm 18 includes an arm body 18A that extends and a roller 18B that is rotatably supported at an intermediate portion in the longitudinal direction of the arm body 18A. The arm main body 18A is rotatably supported at the distal end portion of the plunger 22 at the proximal end portion. An injection hole 18 </ b> C connected to the distal end hole 33 of the plunger 22 is formed at the base end portion of the arm main body 18 </ b> A. The oil in the reservoir chamber 30 is supplied to the slidable contact portion between the plunger 22 and the arm main body 18A through the tip hole 33 and is sprayed from the injection hole 18C toward the slidable contact portion between the roller 18B and the cam 16A. The tip of the arm body 18A is in contact with the upper end of the stem portion 10A of the valve 10. The roller 18B is in contact with the cam 16A of the camshaft 16. The rotation direction of the camshaft 16 is determined so that the cam 16A pushes the roller 18B from the distal end side of the arm body 18A.

  As shown in FIG. 3, when the camshaft 16 rotates, the cam 16A pushes the rocker arm 18 downward at a predetermined timing. As a result, the rocker arm 18 rotates about the rotation center O <b> 1 and pushes the valve 10 downward against the urging force of the valve spring 13. As a result, the valve 10 changes from the closed state to the open state.

  When there is a gap between the base circle of the cam 16 </ b> A and the roller 18 </ b> B of the rocker arm 18, the plunger 22 is biased by the plunger spring 37 and protrudes outward from the housing 21 to fill the gap. When the plunger 22 protrudes, oil flows from the reservoir chamber 30 through the proximal end hole 34 into the pressure chamber 35. When the cam 16A pushes the plunger 22 in the immersion direction via the rocker arm 18, the pressure in the pressure chamber 35 becomes higher than the pressure in the reservoir chamber 30, the check valve 36 is closed, and the immersion of the plunger 22 is restricted.

  As shown in FIG. 1, the position of the rocker arm 18 when the roller 18B of the rocker arm 18 is in contact with the base circle of the cam 16A is set as the initial position. When the rotational speed of the internal combustion engine 1 is less than the maximum allowable rotational speed (over rev) (hereinafter referred to as normal rotation of the internal combustion engine 1), the roller 18B of the rocker arm 18 and the cam 16A of the camshaft 16 maintain contact. As shown in FIG. 3, the position where the rocker arm 18 is most pushed down toward the upper surface 3 </ b> A side of the cylinder head 3 by the cam 16 </ b> A while the contact between the cam 16 </ b> A and the roller 18 </ b> B is maintained. The position of the center O2 of the roller 18B in the post-drive position is displaced toward the upper surface 3A side of the X [mm] cylinder head 3 with respect to the rotation center O1 of the rocker arm 18 with respect to the position of the center O2 of the roller 18B in the initial position. doing. During normal rotation of the internal combustion engine 1, the second valve 44 is kept closed, so that the volume of the first oil chamber 40 is maintained constant, and the position of the housing 21 of the lash adjuster 17 does not change. The rotation center O1 of the rocker arm 18 is maintained at a predetermined position.

  When the rotational speed of the internal combustion engine 1 increases, the load applied from the camshaft 16 to the rocker arm 18 increases, and the load applied from the rocker arm 18 to the lash adjuster 17 increases. As shown in FIG. 4, when the rotational speed of the internal combustion engine 1 is equal to or higher than the maximum allowable rotational speed (hereinafter, referred to as over-rotation of the internal combustion engine 1), the first oil chamber 40 is loaded by the load applied to the lash adjuster 17 from the rocker arm 18. , The second valve 44 is opened, and the oil in the first oil chamber 40 can pass through the discharge oil passage 42 and be discharged into the valve operating chamber 4. Note that the first valve 43 is closed because the hydraulic pressure P1 of the first oil chamber 40 is greater than the hydraulic pressure Ph of the head oil passage 25. As a result, the housing 21 of the lash adjuster 17 moves to the bottom side in the HLA receiving hole 19 against the biasing force of the spring 39 and the hydraulic pressure P1 of the first oil chamber 40, and the rotation center O1 of the rocker arm 18 is moved to the rocker arm. Move to the side opposite to 18. As a result, the amount of movement of the end of the rocker arm 18 on the valve 10 side with respect to the amount of movement of the roller 18B becomes small, and an increase in the lift amount of the valve 10 when the internal combustion engine over-rotates is suppressed.

  Thereafter, when the rotational speed of the internal combustion engine 1 decreases and the inertial force generated in the rocker arm 18 decreases, the hydraulic pressure P1 of the first oil chamber 40 decreases. The second valve 44 is closed when the hydraulic pressure P1 of the first oil chamber 40 falls below the value Ps, and the first valve 43 opens when it falls below the hydraulic pressure Ph of the head oil passage 25. As a result, oil is supplied from the head oil passage 25 to the first oil chamber 40 via the supply oil passage 41, the first oil chamber 40 expands, and the rotation center O1 of the rocker arm 18 returns to the initial position. At this time, when the urging force of the spring 39 is applied, the lash adjuster 17 is quickly returned to the initial position.

  With the above configuration, when the inertial force generated in the rocker arm 18 increases during the over-rotation of the internal combustion engine 1, the rotation center O1 of the rocker arm 18 moves to the side opposite to the camshaft 16, and the amount of movement of the roller 18B The amount of movement of the end of the rocker arm 18 on the valve 10 side is reduced, and an increase in the valve lift is suppressed. Thereby, an increase in the load transmitted from the rocker arm 18 to the valve 10 is suppressed.

(Second Embodiment)
The valve mechanism 50 according to the second embodiment includes a stopper 51 in addition to the valve mechanism 15 described in the first embodiment, and other configurations are the same as those of the valve mechanism 15 described in the first embodiment. It is. In the following description, in the valve operating mechanism 50 according to the second embodiment, the same components as those of the valve operating mechanism 15 described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5, the stopper 51 is a cylindrical pin member, and is movably received in a stopper receiving hole 52 that is a bottomed hole formed in the upper surface 3 </ b> A of the cylinder head 3. The stopper receiving hole 52 forms an end of the discharge oil passage 42 on the side of the upper surface 3 </ b> A of the cylinder head 3, and has a wider cross section than other portions of the discharge oil passage 42. The stopper 51 is movably received at the base end portion in the stopper receiving hole 52, and the outer peripheral surface is in sliding contact with the inner peripheral surface of the stopper receiving hole 52.

  An annular groove (not shown) extending in the circumferential direction is formed on the outer peripheral portion of the stopper 51, and a C-shaped retaining ring 55 is attached to the annular groove. A restriction groove 56 that receives the outer peripheral portion of the retaining ring 55 is formed on the wall surface of the stopper receiving hole 52. The restriction groove 56 has a predetermined width in the axial direction of the stopper receiving hole 52, and the retaining ring 55 can move within a predetermined range in the axial direction of the stopper 51 in the restriction groove 56. The position where the retaining ring 55 contacts the end of the restriction groove 56 on the rocker arm 18 side is the first position of the stopper 51, and the position where the retaining ring 55 contacts the end of the restriction groove 56 opposite to the rocker arm 18 side is the stopper. The second position is 51. That is, the stopper 51 is located at the first position closest to the rocker arm 18 along the axial direction, and the second position positioned on the side opposite to the rocker arm 18 from the first position (on the upper surface 3A side of the cylinder head 3). Is supported by the cylinder head 3 so as to be slidable between the two.

  In the first position, the tip of the stopper 51 is opposed to the roller 18B of the rocker arm 18 in the initial position with a distance of X + G [mm] (a predetermined clearance from the roller 18B of the rocker arm 18 in the post-drive position). Opposite via G). The gap G is set, for example, in a range of 1 mm to 3 mm. A position where the roller 18B is displaced from the initial position to the upper surface 3A side of the X + G [mm] cylinder head 3 is defined as a limit position of the rocker arm 18. The roller 18B of the rocker arm 18 contacts the stopper 51 of the stopper 51 at the limit position. The displacement amount X [mm] and the gap G [mm] from the initial position to the post-drive position may be expressed as an angle with reference to the rotation center O1 of the rocker arm 18. Since the gap G is set, the stopper 51 and the roller 18B of the rocker arm 18 do not come into contact with each other during normal rotation of the internal combustion engine 1. Further, the distal end portion of the stopper 51 is disposed on a rotation locus P at the center of the roller 18B with the rotation center O1 of the rocker arm 18 as the center. The axis A1 of the stopper 51 extends in the tangential direction of the rotation locus P at the center of the roller 18B from the tip portion disposed on the rotation locus P at the center of the roller 18B.

  The base end portion of the stopper 51 and the bottom portion of the stopper receiving hole 52 cooperate with each other to define the second oil chamber 57. The volume of the second oil chamber 57 increases or decreases according to the position of the stopper 51 with respect to the stopper receiving hole 52. The second oil chamber 57 is connected to the first oil chamber 40 via the second valve 44 and receives supply of oil from the first oil chamber 40.

  A biasing device 58 that biases the stopper 51 toward the first position is provided between the stopper 51 and the cylinder head 3. The urging device 58 may be, for example, a spring member such as a compression coil spring or a leaf spring, or a pair of magnets having the same polarity facing each other. The biasing device 58 is not an essential configuration and may be omitted. In the present embodiment, in the second oil chamber 57, an urging device 58 that is a compression coil spring is provided between the base end portion of the stopper 51 and the bottom portion of the stopper receiving hole 52.

  As with the valve mechanism 15 according to the first embodiment, the valve mechanism 50 according to the second embodiment is configured to rotate the rocker arm 18 when the inertial force generated in the rocker arm 18 increases during over-rotation of the internal combustion engine 1. The moving center O1 moves to the side opposite to the camshaft 16, the amount of movement of the end of the rocker arm 18 on the valve 10 side with respect to the amount of movement of the roller 18B decreases, and an increase in the valve lift is suppressed. Thereby, an increase in the load transmitted from the rocker arm 18 to the valve 10 is suppressed.

  Further, when the internal combustion engine 1 is over-rotated, when the second valve 44 is opened and the housing 21 of the lash adjuster 17 moves to the bottom side of the HLA receiving hole 19, the oil in the first oil chamber 40 passes through the discharge oil passage 42. It passes through and is supplied to the second oil chamber 57. When the roller 18B presses the stopper 51, the stopper 51 moves from the first position to the second position, and the oil pressure in the second oil chamber 57 increases. As a result, the oil in the second oil chamber 57 flows from the second oil chamber 57 to the valve operating chamber 4 through a minute gap between the outer peripheral surface of the stopper 51 and the inner peripheral surface of the stopper receiving hole 52. The movement resistance of the stopper 51 is attenuated by the flow resistance of the oil, and the rotation of the rocker arm 18 is attenuated. Thus, the stopper 51 and the stopper receiving hole 52 function as a piston damper using oil. Further, the urging force of the urging device 58 acts in a direction against the movement of the stopper 51 and the rotation of the rocker arm 18, whereby the rotation of the rocker arm 18 is suppressed and the stopper 51 and the rocker arm 18 collide with each other. When the shock is absorbed. As a result, the rotation range of the rocker arm 18 is restricted and the rotation is attenuated. When the rocker arm 18 moves in a direction away from the stopper 51, the second valve 44 continues to be opened, and oil flows from the first oil chamber 40 into the second oil chamber 57, and the stopper 51 returns to the first position. . The urging force of the urging device 58 also acts as a driving force that returns the stopper 51 to the first position.

(Third embodiment)
Next, a valve mechanism 60 according to a third embodiment in which the second valve 44 of the valve mechanism 50 according to the second embodiment is an electromagnetic valve will be described. The second valve 59 is a known electromagnetic valve that is controlled to open and close in response to a signal from the control device 68, and is, for example, a spool valve. FIG. 7 shows an example in which the second valve 59 is a spool valve. As shown in FIG. 7A, the second valve 59 is provided in the cylinder head 3 so as to reciprocate in the cylindrical valve receiving hole 61 formed so as to cross the discharge oil passage 42. A cylindrical valve body 62, a spring 63 that biases the valve body 62 toward the valve closing position, and an actuator 64 that is coupled to the valve body 62 and drives the valve body 62. A step portion 65 is formed on the inner peripheral surface of the valve receiving hole 61 to contact the valve body 62 and determine the initial position of the valve body 62. In the initial state where the valve body 62 is in contact with the stepped portion 65, a liquid chamber 66 is formed between the valve receiving hole 61 and the valve body 62 on one end side of the valve receiving hole 61. The liquid chamber 66 is connected to a portion on the upstream side (first oil chamber 40 side) with respect to the valve receiving hole of the discharge oil passage 42 by a passage 67. The spring 63 is, for example, a compression coil spring, and is provided between the other end of the valve receiving hole 61 and the valve body 62. The actuator 64 is a solenoid, for example, and is driven by a signal from the control device 68 to move the valve body 62 against the urging force of the spring 63. The valve body 62 is formed with a connection hole 62A penetrating in a direction orthogonal to the reciprocating direction. When the valve body 62 is in the valve closing position, the connection hole 62 </ b> A and the drain oil passage 42 are located away from each other, and the drain oil passage 42 is blocked by the valve body 62. On the other hand, when the valve body 62 is moved to the other end side of the valve receiving hole 61 by the actuator 64, the connection hole 62A and the discharge oil passage 42 are connected, and the oil flows through the connection hole 62A and the discharge oil passage 42. The opening degree of the second valve 59 varies depending on the position of the valve body 62.

  With reference to FIG.8 and FIG.9, the operation | movement and effect | action of the valve mechanism 60 which concerns on 3rd Embodiment, the valve mechanism 50 which concerns on 2nd Embodiment, and the valve mechanism which concerns on a comparative example are demonstrated. The valve mechanism according to the comparative example makes the housing 21 of the lash adjuster 17 immovable to the cylinder head 3 with respect to the valve mechanism 50 according to the second embodiment (that is, the first oil chamber 40 is omitted). The conventional valve operating mechanism in which the stopper 51 is omitted.

8A and 8B, the valve lift that is the position of the valve 10, the rocker arm position that is the position of the rocker arm 18, the HLA position that is the position of the lash adjuster 17, and the position of the stopper 51 are based on normal rotation. The difference is described. That is, “0” in the table indicates that it is in the same position as each component during normal rotation. The crank phases (i) to (iv) in FIGS. 8A, 8B and 9 correspond to each other.

  As shown in FIG. 9, the valve mechanism 60 according to the third embodiment, the valve mechanism 50 according to the second embodiment, and the valve mechanism according to the comparative example are all predetermined during normal rotation of the internal combustion engine 1. Lift curve 100 (solid line). On the other hand, in the valve mechanism according to the comparative example, as shown in FIG. 8B, the rocker arm 18 is separated from the camshaft 16 when the internal combustion engine 1 is over-rotated, and the displacement amount of the rocker arm 18 is increased. The valve 10 moves away from the rocker arm 18 and the valve lift becomes like a lift curve 101 (broken line) in FIG.

  In the valve operating mechanism 60 according to the third embodiment, when the control device 68 determines that the internal combustion engine 1 is in an overspeed state, the second valve 59 is controlled to open and close. The control device 68 determines whether or not the internal combustion engine 1 is in an overspeed state, for example, by comparing the rotation speed of the crankshaft with a predetermined rotation speed threshold. When the control device 68 determines that the internal combustion engine 1 is in an overspeed state, as shown in FIG. 7A, when the crank phase is (ii) or (iii), the control device 68 turns on the second valve 59 that is an electromagnetic valve. Open and close the second valve 59 which is a solenoid valve at (i) and (iv). Thereby, in the phase (ii), the oil flows from the first oil chamber 40 through the discharge oil passage 42 to the second oil chamber 57, and the lash adjuster 17 can move to the bottom side of the HLA receiving hole 19. Further, when the stopper 51 comes into contact with the rocker arm 18, the movement of the rocker arm 18 is suppressed. When the lash adjuster 17 and the stopper 51 move, the oil passes through the first valve 43, the second valve 59, and between the stopper 51 and the stopper receiving hole 52, and the flow resistance thereof passes through the lash adjuster 17 and the stopper 51. It acts on the rocker arm 18 as a damping force. Thereby, as shown in FIG. 8A, the displacement of the rocker arm 18 and the valve 10 is suppressed as compared with the comparative example, and the valve lift becomes like a lift curve 102 (one-dot chain line) as shown in FIG. As shown in FIG. 9, the difference ΔL1 between the maximum value of the lift curve 102 at the time of excessive rotation of the valve mechanism 60 according to the third embodiment and the maximum value of the lift curve 100 at the time of normal rotation is related to the comparative example. The difference is smaller than the difference ΔL2 between the maximum value of the lift curve 102 when the valve operating mechanism is over-rotated and the maximum value of the lift curve 100 during normal rotation.

  When the second valve 59 is opened in the phases (ii) and (iii), the second valve 59 is greatly opened in the phase (ii), so that the movement of the lash adjuster 17 toward the bottom side of the HLA receiving hole 19 is accelerated. . Further, by reducing the opening degree of the second valve 59 in the phase (iii) than in the phase (ii), the negative pressure in the first oil chamber 40 is increased, and the supply of oil to the first oil chamber 40 is quickly performed. Become. That is, the lash adjuster 17 is quickly returned to the initial position. Such opening operation of the second valve 59 is preferably performed such that the opening is maximized in the phase (ii) and then the opening gradually decreases. For example, when electric power is supplied to the actuator 64 in the phase (ii) to dispose the valve body 62 at a predetermined open position and then the power supply to the actuator 64 is stopped, the valve body 62 is moved to the initial position by the biasing force of the spring 63. And the opening gradually decreases.

  As shown in FIG. 8A, in the valve mechanism 50 according to the second embodiment, as described above, the second valve 59 is opened in the phase (ii) due to the increase in the pressure of the first oil chamber 40, and the second The second valve 59 is closed in the phase (iii) due to the decrease in the pressure in the one oil chamber 40. As shown in FIG. 9, the valve mechanism 50 according to the second embodiment has the same lift curve 102 as the valve mechanism 60 according to the third embodiment.

(Fourth embodiment)
As shown in FIG. 10, in the valve mechanism 70 according to the fourth embodiment, an injection hole 71 is formed in the stopper 51 in addition to the configuration of the valve mechanism 50 of the second embodiment. The injection hole 71 passes through the central portion of the stopper 51 in the axial direction. The injection hole 71 communicates the second oil chamber 57 and the valve operating chamber 4, and the opening end on the valve operating chamber 4 side faces the roller 18 </ b> B through a gap. Since the pressure in the second oil chamber 57 is relatively high due to the oil supplied from the head oil passage 25, the oil in the second oil chamber 57 is ejected from the ejection hole 71 toward the roller 18B.

  According to the above configuration, the roller 18B is lubricated by the oil injected from the injection hole 71 at the time of normal rotation and excessive rotation of the internal combustion engine 1. Further, since the roller 18B rotates from the base end side (lash adjuster 17 side) to the tip end side (valve 10 side) of the rocker arm 18 on the lower side (cylinder head 3 side), The oil sprayed to 18B scatters to the tip end side of the rocker arm 18 by the rotation of the roller 18B, and the sliding contact portion between the rocker arm 18 and the valve 10 is lubricated. In addition, when the internal combustion engine 1 is excessively rotated, when the stopper 51 moves to the second position side, the flow resistance when oil passes through the injection hole 71 acts on the rocker arm 18 as a damping force. Can be attenuated.

  In the valve operating mechanisms 15, 50, 60, 70 according to the first to fourth embodiments described above, the housing 21 of the lash adjuster 17 is received by the camshaft 16 in response to the inertial force generated in the rocker arm 18 when the internal combustion engine 1 is over-rotated. The pivot center O1 of the rocker arm 18 moves to the side opposite to the camshaft 16. As a result, the amount of movement of the end of the rocker arm 18 on the valve 10 side with respect to the amount of movement of the roller 18B decreases, and an increase in the valve lift amount is suppressed. In the valve mechanisms 50 and 70 according to the second to fourth embodiments, the stopper 51 comes into contact with the roller 18B of the rocker arm 18 when the internal combustion engine 1 is over-rotated, and the rotation range of the rocker arm 18 is restricted. As a result, an increase in the load transmitted from the rocker arm 18 to the valve 10 is suppressed. Therefore, there is no need to increase the spring constant of the valve spring 13, and fuel consumption is prevented from deteriorating. Further, since the load applied to the valve 10 and the spring retainer 12 is reduced, the rigidity required for the valve 10 and the spring retainer 12 is reduced.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. The valve operating mechanisms 15, 50, 70 are not limited to the DOHC type, but may be an OHC type or an OHV type.

  Further, the second valve 44 in the first embodiment and the fourth embodiment may be replaced with a second valve 59 which is the same electromagnetic valve as in the third embodiment.

1: Internal combustion engine 3: Cylinder head 3A: Upper surface 4: Valve chamber 10: Valves 15, 50, 60, 70: Valve mechanism 16: Camshaft 17: Rush adjuster 18: Rocker arm 18B: Roller 19: HLA receiving hole 21 : Housing 22: Plunger 40: First oil chamber 41: Supply oil passage 42: Drain oil passage 43: First valve 44: Second valve 51: Stopper 52: Stopper receiving hole 57: Second oil chamber 58: Energizing device 71: injection hole

Claims (11)

A valve mechanism for an internal combustion engine,
A bottomed receiving hole formed in the cylinder head;
A hydraulic lash adjuster having a base end received in the receiving hole in a predetermined range in the axial direction of the receiving hole;
A rocker arm that is rotatably supported at the tip of the lash adjuster protruding from the receiving hole and is driven by a camshaft;
A valve provided in the cylinder head and opened by being pushed by the rocker arm;
A first oil chamber that is defined in cooperation with a bottom portion of the receiving hole and a base end portion of the lash adjuster, and whose volume is increased or decreased by movement of the lash adjuster with respect to the receiving hole;
A supply oil passage connecting the oil passage formed in the cylinder head and the first oil chamber;
An oil discharge passage connecting the first oil chamber and the outer surface of the cylinder head;
A first valve that is provided in the supply oil passage and blocks oil flow from the first oil chamber to the oil passage, while allowing reverse oil flow;
The exhaust oil passage is provided in the exhaust oil passage to block the flow of oil from the outer surface of the cylinder head to the first oil chamber, while the pressure on the first oil chamber side in the exhaust oil passage is on the outer surface side of the cylinder head. A valve operating mechanism for an internal combustion engine, comprising: a second valve that allows a flow from the first oil chamber side to the outer surface side of the cylinder head when the pressure is greater than a predetermined value. A bottomed stopper receiving hole that forms a part of the drain oil passage and opens to the outer surface of the cylinder head;
A stopper received in the stopper receiving hole movably within a predetermined range;
A bottom portion of the stopper receiving hole and a base end portion of the stopper are cooperatively defined, and has a second oil chamber whose volume is increased or decreased by movement of the stopper;
The stopper includes a first position where the rocker arm contacts the rocker arm when the rocker arm is at a predetermined limit position away from the camshaft, and a second position located in a direction opposite to the rocker arm with respect to the first position. The valve operating mechanism for an internal combustion engine according to claim 1, wherein the valve operating mechanism is movable between   3. The valve operating mechanism for an internal combustion engine according to claim 2, wherein the stopper extends in a tangential direction centering on a rotation center of the rocker arm when the rocker arm is in the limit position. The rocker arm has an arm main body rotatably provided on the cylinder head, and a roller rotatably supported by the arm main body and contacting the camshaft,
4. The valve operating mechanism for an internal combustion engine according to claim 2, wherein the stopper contacts the roller when the rocker arm is in the limit position. 5. A biasing device that biases the stopper toward the first position is provided between the cylinder head and the stopper,
5. The valve operating mechanism for an internal combustion engine according to claim 2, wherein the urging device is at least one of a spring member and a magnet pair with the same pole facing each other.   The said stopper has an injection hole extended in the front-end | tip part which opposes the said rocker arm from the base end part which opposes the said 2nd oil chamber, The Claim 1 characterized by the above-mentioned. A valve mechanism for an internal combustion engine.   The opening end at the tip portion of the injection hole is provided in the rocker arm and faces a portion of the roller that contacts the camshaft that is opposite to the camshaft. Of the internal combustion engine.   8. The valve operating mechanism for an internal combustion engine according to claim 7, wherein the roller is in sliding contact with the camshaft so that a side facing the stopper rotates toward the valve side.   The valve of an internal combustion engine according to any one of claims 1 to 8, wherein the second valve is a valve that opens when a difference in pressure acting on both ends is a predetermined value or more. mechanism.   9. The valve operating mechanism for an internal combustion engine according to claim 1, wherein the second valve is an electromagnetic valve that is controlled to open and close based on a signal from a control device.   11. The valve operating mechanism for an internal combustion engine according to claim 10, wherein the second valve is controlled to open and close based on a rotational speed of a crankshaft.

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