JP4176031B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake or exhaust engine valve urged in a valve closing direction by a valve spring, that is, a variable valve operating apparatus for an internal combustion engine that opens and closes an intake valve or an exhaust valve.

  Various variable valve operating devices that can change the opening / closing operation of an intake valve or an exhaust valve have been conventionally developed as follows.

(1) Cam type + Electromagnetic actuator holding type An electromagnetic actuator is arranged between the valve spring receiver provided at the upper end of the valve shaft and the cylinder head, and the valve drive cam is used to open the valve. (See Patent Document 1).

(2) All-cam type + All-hydraulic type The entire opening and closing process from the valve opening operation to the valve closing operation is performed by selectively switching between cam-type power transmission means and hydraulic power transmission means (patent) Reference 2).

Japanese Unexamined Patent Publication No. 63-289208 JP-A-6-117210

  The former cam type + electromagnetic actuator holding type is a so-called lost motion type, in which the lift by the cam is the maximum valve opening range, and the variable range by the electromagnetic actuator is limited to the cam lift range. FIG. 15 shows the change of the valve lift in the cam type + electromagnetic actuator holding type. When the curve Y1 shown by the solid line is the lift by the cam, the valve lift changed by the electromagnetic actuator is as shown by the broken lines Y2, Y3. It is restricted within the valve lift Y1 by the cam and cannot be expanded beyond Y1, and the variable range is greatly restricted. By the way, if the variable range is to be expanded, the cam profile must be changed to make the cam crest high and long in the rotational direction, which complicates cam machining.

  In the latter full-cam type + full-hydraulic type, when switching to the full-hydraulic type, the entire period from the valve opening start timing to the valve closing end timing is operated with hydraulic pressure. In order to operate the engine valve against the spring, hydraulic oil must be used at a high pressure, resulting in a large engine output loss and complicated hydraulic equipment and piping equipment for high pressure. This leads to an increase in the part cost. Also, it takes time for maintenance.

  In order to solve the above-mentioned problems, an invention according to claim 1 of the present application is directed to a variable valve operating apparatus for an internal combustion engine that opens and closes an intake or exhaust engine valve biased in a valve closing direction by a valve spring. A hydraulic valve opening holding mechanism that has a valve opening holding piston that acts on the engine valve separately from the valve driving cam mechanism and delays the closing operation of the engine valve from the valve closing operation by the valve driving cam mechanism; And the engine valve is operated by the valve drive cam mechanism during the valve opening operation period, and the valve drive cam mechanism and the hydraulic valve opening holding mechanism are alternatively operated during the valve closing operation period.

  According to a second aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the first aspect, the valve opening holding height of the engine valve when the valve opening holding mechanism is selected by controlling the operation of the valve opening holding piston. In addition, the valve opening holding period can be changed continuously.

  According to a third aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the first or second aspect, the operation of the valve opening holding piston is controlled to close the engine valve when the hydraulic valve opening holding mechanism is selected. The valve start time can be changed.

A fourth aspect of the present invention is the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, wherein the valve drive cam mechanism is linked to the engine valve via a tappet, a push rod, and a valve arm in this order. The push rod is connected to the valve arm so that the joint portion fixed integrally with the push rod is movable relative to the valve arm in the push rod moving direction, and is pressed against the cam surface of the valve drive cam by the auxiliary spring, And the said joint part is formed with the recessed part into which the volt | bolt provided in the valve arm is inserted as a drop-off prevention mechanism.

  According to a fifth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the hydraulic valve opening holding mechanism is in a valve opening holding state when the hydraulic valve opening holding mechanism is selected. A seat cushioning mechanism that limits the seating speed of the engine valve when the engine is released.

  According to a sixth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the fifth aspect, a variable orifice is provided at a hydraulic oil outlet of the hydraulic chamber as a seating buffer mechanism.

  According to a seventh aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the sixth aspect, as a seating buffer mechanism, a hydraulic orifice is provided in a hydraulic oil outlet of a hydraulic chamber, and a hydraulic oil inlet having an electromagnetic on-off valve. Is opened at the bottom of the hydraulic chamber, and the electromagnetic on-off valve is opened at the end of the lowering operation of the valve-opening holding piston.

  According to an eighth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the valve-opening holding piston is disposed so as to protrude upward from the hydraulic chamber.

  According to a ninth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the hydraulic fluid in the hydraulic chamber is opened when the hydraulic fluid pressure in the hydraulic chamber exceeds a predetermined value. A relief valve is provided.

  According to a tenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the hydraulic valve opening holding mechanism separate from the valve driving cam mechanism is a valve driving cam mechanism. The main body of the internal combustion engine provided is detachably attached.

  The invention according to claim 11 is the variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the hydraulic oil outlet of the hydraulic chamber is a hydraulic pressure of a hydraulic valve opening and holding mechanism for another engine valve. The hydraulic fluid that communicates with the hydraulic fluid inlet of the chamber and supplies the hydraulic fluid discharged from the hydraulic chamber when the valve opening retention by the hydraulic valve opening retention mechanism is released is supplied to the hydraulic chamber of the other hydraulic valve opening retention mechanism. It is.

  A twelfth aspect of the present invention is the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, wherein the maximum height of the engine valve determined by the cam surface of the valve drive cam mechanism is the valve curtain area. Is suppressed to an extent that is substantially the same as the flow cross-sectional area of the valve seat portion.

  According to a thirteenth aspect of the present invention, in the variable valve operating system for an internal combustion engine according to any one of the first to third aspects, the valve opening holding start timing by the hydraulic valve opening holding mechanism is the engine valve for exhaust and the engine piston. Is set to a valve height that does not interfere.

  According to a fourteenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, on the cam surface of the valve drive cam mechanism, in addition to a normal cam crest for opening and closing the engine valve A cam ridge for re-opening is formed, and the re-opening period is variable by a hydraulic valve opening holding mechanism.

  According to a fifteenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, a valve drive cam mechanism is provided for each of an intake engine valve and an exhaust engine valve in one cylinder. In addition, a hydraulic valve opening and holding mechanism is provided, and the hydraulic oil discharge portion of each hydraulic valve opening and holding mechanism is opened and closed by a common electromagnetic on-off valve.

  According to a sixteenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the internal combustion engine has a plurality of cylinders. The hydraulic oil discharge part of the hydraulic valve opening and holding mechanism is opened and closed.

  According to a seventeenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to any one of the first to third aspects, the hydraulic valve opening holding mechanism has a valve closing speed adjusting mechanism capable of adjusting a valve closing speed. is doing.

  According to an eighteenth aspect of the present invention, in the variable valve operating apparatus for the internal combustion engine according to the seventeenth aspect, the valve closing speed adjusting mechanism includes a notch formed in the valve opening holding piston and a variable orifice opening in the hydraulic chamber. The area where the notch covers the opening of the variable orifice can be adjusted by rotating the valve-opening holding piston.

  According to a nineteenth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the seventeenth aspect, a plurality of notches formed in the valve opening holding piston are formed in the movement direction of the valve opening holding piston.

  According to a twentieth aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the nineteenth aspect, the plurality of notches are disposed so as to sequentially decrease the valve closing speed when the valve is closed after releasing the valve holding. Yes.

(1) An opening operation of an engine valve such as an intake valve or an exhaust valve is always performed by a valve driving cam mechanism, and the valve closing operation is performed by either a valve driving cam mechanism or a hydraulic valve opening holding mechanism having a valve opening holding piston. Therefore, it is not necessary to provide a high-pressure pump to drive the hydraulic valve-opening holding mechanism, and the mechanical loss can be reduced. A variable valve device can be provided.

(2) When the engine valve is closed, a valve drive cam mechanism and a hydraulic valve opening and holding mechanism are used alternatively, so that the hydraulic valve opening and holding mechanism is used in comparison with the conventional cam type and electromagnetic actuator type. The operating range can be set freely and wider than the operating range of the valve drive cam mechanism, and the degree of freedom of the valve closing operating range increases.

(3) When a valve-opening holding piston that holds the engine valve in an open state against the valve spring is used as a hydraulic valve-opening holding mechanism, the valve-opening holding piston can be brought into contact with a valve arm, for example. It is only necessary to arrange them so as to face each other, and the assembly work of the hydraulic valve opening and holding mechanism is simplified.

(4) By controlling the operation of the valve opening holding piston, the valve opening holding height and the valve opening holding period of the engine valve when the valve opening holding mechanism is selected can be continuously changed. The valve lift characteristic when the valve is closed can be set to a desired characteristic easily and freely, and the valve closing start time can be easily and freely selected.

(5) In an OHV type internal combustion engine provided with a valve arm, the joint portion of the push rod is connected to the valve arm so as to be relatively movable in the push rod moving direction, and the push rod is connected to the cam surface of the valve drive cam by an auxiliary spring. Even when the hydraulic valve opening holding mechanism is selected during the valve closing operation, the joint portion is provided with a recess into which the bolt provided on the valve arm is inserted as a drop prevention mechanism. The operation of the push rod of the valve drive cam mechanism can be maintained in a smooth state.

(6) If a seating buffering mechanism is provided that limits the seating speed of the valve when the valve-opening holding state when the hydraulic valve-opening holding mechanism is selected, the valve seating operation when the hydraulic valve-opening holding mechanism is selected. Can be performed smoothly, and the seating impact and noise of the engine valve can be prevented.

(7) If the variable orifice is provided at the hydraulic oil outlet of the hydraulic chamber as the seating buffer mechanism, the speed until the engine valve is seated can be limited with a simple configuration.

(8) As a seating buffer mechanism, a variable orifice is provided at the hydraulic oil outlet of the hydraulic chamber, the hydraulic oil inlet having an electromagnetic on-off valve is opened at the bottom of the hydraulic chamber, and the electromagnetic is When the on-off valve is opened, it is possible to perform buffering at the time of sitting, and to ensure a reliable valve closing state against changes in the temperature of the hydraulic oil and the like.

(9) If the valve-opening holding piston is arranged so as to protrude upward from the hydraulic chamber, it will open even if the hydraulic chamber is drained when the internal combustion engine is left in a non-operating state for a long time. Since the valve holding piston moves in the direction to close the engine valve or the like, it can be reliably opened and started by the valve drive cam mechanism at the next use. In addition, when the hydraulic oil has been removed from the hydraulic chamber as described above and left for a long period of time, even if the valve-opening holding piston is stuck due to rust or deterioration of the hydraulic oil, it may hinder the start of the period. There is no. Even when the solenoid valve at the hydraulic oil inlet of the hydraulic valve opening and holding mechanism is de-energized, the valve drive cam mechanism can be used to mechanically operate the intake valve, etc. Will not be disturbed.

(10) If a safety valve is provided in the hydraulic chamber, for example, even if the engine valve and the engine piston interfere with each other and excessive pressure is applied to the hydraulic chamber, the hydraulic oil is quickly discharged from the hydraulic chamber and the engine valve is Can move with the piston, thereby preventing engine damage.

(11) When a valve opening holding mechanism separate from the valve driving cam mechanism is detachably attached to the main body of the internal combustion engine having the valve driving cam mechanism, a conventional valve driving cam mechanism only is provided. The internal combustion engine with a variable valve operating apparatus of the present invention can be manufactured with a slight improvement of the engine. In addition, the compatibility between the internal combustion engine having only the valve drive cam mechanism and the internal combustion engine using both the valve drive cam mechanism and the hydraulic valve opening and holding mechanism can be greatly increased. Management costs can be reduced.

(12) The hydraulic oil outlet of the hydraulic chamber communicates with the hydraulic oil inlet of the hydraulic chamber of the hydraulic valve opening and holding mechanism for other engine valves, and the hydraulic pressure is released when the valve opening and holding by the hydraulic valve opening and holding mechanism is released. If hydraulic fluid discharged from the chamber is supplied to the hydraulic chamber of the other hydraulic valve opening and holding mechanism, the engine valve is opened slightly by the pressure when discharged from the hydraulic chamber, regardless of the valve drive cam. I can speak.

(13) If the maximum height of the engine valve determined by the cam surface of the valve drive cam mechanism is suppressed to the extent that the valve curtain area is substantially the same as the flow cross-sectional area of the valve seat portion, the cam height is reduced. The valve drive cam mechanism can be made compact and the design of the valve drive cam becomes easy.

(14) When the valve opening and holding start timing by the hydraulic valve opening and holding mechanism is set to a valve height at which the exhaust engine valve and the engine piston do not interfere with each other, even when the hydraulic valve opening and holding mechanism is selected, The engine will not be damaged by interference.

(15) On the cam surface of the valve drive cam mechanism, a re-opening cam crest is formed in addition to the normal cam crest for engine valve opening and closing, and the re-opening period is made variable by the hydraulic valve opening holding mechanism. In this case, the re-opening period of the exhaust valve can be freely set without complicating the cam shape of the valve drive cam mechanism.

(16) A valve drive cam mechanism and a hydraulic valve opening and holding mechanism are provided for each exhaust valve and intake valve in one cylinder, and both hydraulic valve opening and holding mechanisms are opened and closed by a common electromagnetic on-off valve. In addition, the component cost can be reduced and the size can be reduced.

(17) In a multi-cylinder internal combustion engine, if an electromagnetic on-off valve that opens and closes the hydraulic oil discharge part of the valve opening holding mechanism of each cylinder is shared, the parts cost can be reduced and the size can be reduced.

(18) When the valve-opening holding mechanism is provided with the valve-closing speed adjusting mechanism, the valve-closing speed of the engine valve can be adjusted by adjusting the descending speed of the valve-opening holding piston, thereby obtaining a more optimal valve lift characteristic. be able to.

(19) The valve closing speed adjusting mechanism is composed of a notch formed in the valve opening holding piston and a variable orifice opening in the hydraulic chamber, and the notch is variable by rotating the valve opening holding piston. If the area covering the orifice opening can be adjusted, the valve opening holding piston can be adjusted by simply adjusting the valve opening holding piston so that the lowering speed of the valve opening holding piston can be adjusted. Can be delayed.

(20) If a plurality of notches formed in the valve-opening holding piston are formed in the movement direction of the valve-opening holding piston, the lowering speed of the valve-opening holding piston can be controlled in a plurality of stages, and a more appropriate engine valve A closing action can be obtained.

(21) When the plurality of notches are arranged so that the valve closing speed is sequentially decreased during the valve closing operation after the valve opening holding is released, the lowering speed of the valve opening holding piston can be controlled to be sequentially decreased. Therefore, a more appropriate closing operation of the engine valve can be obtained.

[First Embodiment of the Invention]
(Engine valve and valve drive cam mechanism)
1 to 5 show examples in which the variable valve operating apparatus of the present invention is applied to an OHV type internal combustion engine. In the claims, they are expressed as an exhaust engine valve and an intake engine valve. However, since they are so-called exhaust valves and intake valves, they are specifically referred to as exhaust valves or intake valves in the embodiments. explain. FIG. 1 is a schematic vertical sectional view in the vicinity of an exhaust valve. In FIG. 1, an exhaust passage 2 is formed in a cylinder head 1, and one end of the exhaust passage 2 opens into a combustion chamber 5 as an exhaust port 3. Yes. An exhaust valve 7 is disposed in the exhaust port 3 so as to be openable and closable, and can be seated on the valve seat 8.

  A valve shaft 7 a of the exhaust valve 7 is slidably supported by the cylinder head 1 via a valve bearing body 9 and protrudes into the upper valve arm chamber 10. A disc-shaped spring receiver 11 is fixed to the upper end portion of the valve shaft 7 a, and a valve spring 12 is contracted between the spring receiver 11 and the bottom surface of the valve arm chamber 10. Thus, the exhaust valve 7 is urged upward and is seated on the valve seat portion 8.

  The upper end surface of the valve shaft 7a is in contact with the one end pressing portion 15a of the exhaust valve arm 15 having both arms from above. The exhaust valve arm 15 is swingably supported by the valve arm shaft 17 provided in the valve arm chamber 10, and the one end pressing portion 15a is in contact with the upper end of the valve shaft 7a as described above. A first bolt 20 for transmitting cam power and a second bolt 21 for the hydraulic valve opening and holding mechanism 50 are screwed into the other end of the arm 15, and both bolts 20, 21 are connected to the valve arm 15. A fixed amount protrudes downward from the lower surface and is fixed by lock nuts 22 and 23 so that the amount of protrusion can be adjusted. The first bolt 20 is located closer to the valve arm axis O1 than the second bolt 21. That is, the distance from the valve arm axis O 1 to the first bolt 20 is shorter than the distance from the valve arm axis O 1 to the second bolt 21.

  The first bolt 20 is connected to an exhaust cam 33 via a push rod 31 and a tappet 32, and an exhaust valve drive cam mechanism is formed by the first bolt 20, the push rod 31, the tappet 32, the exhaust cam 33, and the like. 30. The exhaust cam 33 is formed on a cam shaft 35 parallel to the valve arm shaft 17, and is connected to the crankshaft so as to rotate once by two rotations of the crankshaft as is well known. The tappet 32 is slidably fitted and supported in a support hole 36 formed in the engine body, and the lower end portion of the push rod 31 is inserted into the tappet 32.

FIG. 2 is an enlarged view of the vicinity of the other end portion of the exhaust valve arm 15, and a joint portion 40 having a spring receiving collar 38 is integrally fixed to the upper end portion of the push rod 31. A concave portion 41 is formed as a connecting portion with the first bolt 20, and a lower end portion of the first bolt 20 is inserted into the concave portion 41 so as to be movable in the push rod moving direction, and is in contact with the bottom surface of the concave portion 41. It touches. An auxiliary spring 45 is contracted between the collar 38 of the joint portion 40 and the annular step portion 43 formed in the cylinder head 1, and the auxiliary spring 45 urges the push rod 31 downward. One tappet 32 is always in contact with the exhaust cam 33.
(Hydraulic valve opening holding mechanism)

  In FIG. 2, the upper end of the valve opening holding piston 51 of the hydraulic valve opening holding mechanism 50 provided in the cylinder head 1 contacts the lower end of the second bolt 21 screwed to the exhaust valve arm 15. Opposite possible. The valve-opening holding piston 51 is fitted in a hydraulic chamber 52 formed in the cylinder head 1 so as to be slidable in the vertical direction, and moves upward by supplying hydraulic oil to the hydraulic chamber 52. Yes. The hydraulic chamber 52 includes a hydraulic oil inlet 66 a formed on the lower end side wall of the hydraulic chamber 52, a small-diameter fixed orifice 54 formed on the side wall slightly above the lower end of the hydraulic chamber 52, and the fixed orifice 54. A variable orifice 53 formed above a certain height is opened, and the hydraulic oil inlet 66a is connected to an oil pump 56 via an electromagnetic opening / closing valve 55 for driving a valve opening holding piston. After the two orifices 53 and 54 have joined together, they are connected to an oil tank 58 via a hydraulic oil outlet electromagnetic opening / closing valve 59.

  FIG. 3 is a detailed cross-sectional view of the hydraulic valve opening and holding mechanism 50. A discharge port 61 having a safety valve 60 is opened on the bottom wall of the hydraulic chamber 52, and when the pressure in the hydraulic chamber 52 becomes a predetermined value or more. The safety valve 60 is opened, and the hydraulic oil in the hydraulic chamber 52 is released from the discharge port 61.

  The drive electromagnetic on-off valve 55 is composed of a drive spool 63, a solenoid 64, and the like. The drive spool 63 has a small-diameter portion 63a at the center in the spool axial direction and large-diameter portions 63b and 63c in the vertical direction, and is slidable in the axial direction in a cylindrical hole 67 formed in the hydraulic oil inlet passage 66. A return spring 68 is interposed between the bottom surface of the cylindrical hole 67 and the lower end of the spool. When the solenoid 64 is not energized, the central small diameter portion 63a is positioned in the hydraulic oil inlet passage 66, so that the hydraulic oil inlet passage 66 is in an open state, hydraulic oil is supplied from the oil pump 56 into the hydraulic chamber 52, and the solenoid 64 is When energized, the spool 63 is pushed down against the return spring 68, and the hydraulic oil inlet passage 66 is blocked by the upper large diameter portion 63b.

  The two orifices 53 and 54 opened in the side wall of the hydraulic chamber 52 constitute a seating buffer mechanism. The variable orifice 53 formed on the upper side has an inner diameter of, for example, 5 mm, and is gradually closed by the outer peripheral surface of the valve-opening holding piston 51 in the downward stroke of the valve-opening holding piston 51, and the opening area with respect to the hydraulic chamber 52 decreases. It is like that. The fixed orifice 54 formed on the lower side has a very small inner diameter, for example, 1Φ mm. The hydraulic oil outlet electromagnetic on-off valve 59 disposed in the hydraulic oil outlet passage (hydraulic oil discharge portion) 69 in which both the orifices 53 and 54 communicate with each other is similar to the driving electromagnetic on-off valve 55 in the same manner as the driving spool 73 and solenoid. 74 or the like. The drive spool 73 has a small-diameter portion 73a at the center in the spool axial direction and large-diameter portions 73b and 73c in the vertical direction, and is slidable in the axial direction in a cylindrical hole 77 formed in the hydraulic oil inlet passage 69. A return spring 78 is interposed between the bottom surface of the cylindrical hole 77 and the lower end of the spool 73. When the solenoid 74 is not energized, the central small-diameter portion 73a is located in the hydraulic oil outlet passage 69, so that the hydraulic oil in the hydraulic chamber 52 can be released through both the orifices 53 and 54. When the solenoid 74 is energized, the spool 73 is pushed down against the return spring 78, and the hydraulic oil outlet passage 69 is closed by the upper large diameter portion 73b.

(Setting 1 and action 1 of hydraulic valve closing mechanism)
FIG. 5 is a diagram showing the valve lift characteristics of the exhaust valve. A curve X1 indicated by a solid line indicates the valve lift characteristics by the valve drive cam mechanism 30 (FIG. 1), and the curves X2 and X3 indicated by broken lines are the above figures. 3 shows an example of the valve lift characteristic during the valve closing operation that can be set by the hydraulic valve opening and holding mechanism 50 of FIG.

  For example, when it is desired to obtain the valve lift characteristic of the curve X2, the hydraulic oil is supplied to the hydraulic chamber 52 by opening the drive electromagnetic on-off valve 55 in FIG. 2 in parallel with the valve opening operation by the valve drive cam mechanism 30 in FIG. 3 and at the same time or subsequently as the exhaust valve 7 reaches the maximum open position A1 in FIG. 5, the valve opening holding piston 51 in FIG. 3 also protrudes upward to the maximum protrusion height H1, and at the height H1. Then, the drive electromagnetic on-off valve 55 is set to be closed. On the other hand, the hydraulic oil outlet electromagnetic on-off valve 59 is set to maintain the closed state from the time when the valve-opening holding piston 51 starts to rise to the position A2 in FIG. 5 and to open at the position A2.

  When set as described above, in the exhaust stroke, first, the other end portion of the exhaust valve arm 15 is pushed up by the push rod 31 of the valve drive cam mechanism 30 of FIG. 1, whereby the exhaust valve 7 resists the valve spring 12. Then, the valve is opened to open from the seating position A0 to the maximum opening position A1 indicated by the phantom line. That is, the valve is opened with the valve lift characteristic shown in the valve opening operation period T1 of the curve X1 in FIG.

  After the exhaust valve is fully opened, the push rod 31 in FIG. 1 starts to descend, but the valve-opening holding piston 51 is maintained at the maximum height H1 in FIG. 3, and thereby the valve arm 15 is moved via the second bolt 21. In order to hold, the exhaust valve 7 of FIG. 1 is held in a fully open state. That is, at the position A1 in FIG. 5, the curve changes from the solid curve X1 to the broken curve X2.

  When the valve holding period T2 ends while the exhaust valve is fully open, the hydraulic oil outlet electromagnetic on-off valve 59 in FIG. 3 opens at the position A2, and the hydraulic oil in the hydraulic chamber 52 begins to be discharged from the orifices 53 and 54. The valve-opening holding piston 51 starts to descend from the maximum height H1.

  When the opening portion of the variable orifice 53 starts to be closed by the outer peripheral surface of the valve opening holding piston 51 in the downward stroke of the valve opening holding piston 51, the amount of hydraulic oil discharged from the variable orifice 53 decreases, thereby causing the valve opening holding piston 51 to be closed. The lowering speed of the exhaust valve becomes slower, and thus the closing speed of the exhaust valve 7 in FIG. 1 also becomes slower. That is, the seating speed of the exhaust valve 7 starts to be buffered. When the variable orifice 53 is fully closed and hydraulic oil is discharged only from the small fixed orifice 54, the lowering speed of the valve holding piston 51 is minimized, and the seating speed of the exhaust valve 7 is most buffered. It becomes a state. When the valve-opening holding piston 51 approaches the bottom surface of the hydraulic chamber 52 and immediately before the seating, the working oil is discharged only from the fixed orifice 54 having an extremely small inner diameter. Therefore, when the viscosity of the working oil is high, the seating speed May be delayed and seating may be delayed, but by opening the driving electromagnetic on-off valve 55 and completely discharging the remaining hydraulic oil in the hydraulic chamber 52, the seating state of the exhaust valve 7 can be reliably established. Can be secured.

  In this embodiment, when the valve opening holding piston 51 of the hydraulic valve opening holding mechanism 50 is raised, it is performed in a state where it is separated from the force of the valve spring 12 applied to the valve arm 15 from the exhaust valve 7. By simply supplying low-pressure hydraulic oil from 56, the valve-opening holding piston 51 can be sufficiently raised, and a high-pressure pump or the like is not necessary.

(Valve closed holding mechanism setting 2 and action 2)
When it is desired to obtain the valve lift characteristic of the curve X3 in FIG. 5, the hydraulic chamber 52 is opened by opening the drive electromagnetic on-off valve 55 in FIG. 2 in parallel with the valve opening operation by the valve drive cam mechanism 30 in FIG. 3 is set so that the driving electromagnetic on-off valve 55 is closed when the valve-opening holding piston 51 of FIG. 3 protrudes upward to the height H3. On the other hand, the hydraulic oil outlet electromagnetic opening / closing valve 59 is set to maintain the closed state from the time when the valve-opening holding piston 51 starts to rise to the position A4 in FIG.

  When set as described above, in the exhaust stroke, first, the other end portion of the exhaust valve arm 15 is pushed up by the push rod 31 of the valve drive cam mechanism 30 of FIG. 1, whereby the exhaust valve 7 resists the valve spring 12. Then, the valve is opened to open from the seating position A0 to the maximum opening position A1 indicated by the phantom line. That is, the valve is opened with the valve lift characteristic shown in the valve opening operation period T1 of the curve X1 in FIG.

  During the opening operation of the exhaust valve 7, the valve-opening holding piston 51 protrudes to the height H3 in FIG. 3 and is held at the height H3.

  After the exhaust valve is fully opened, as the push rod 31 is lowered, the exhaust valve 7 starts to close by the action of the valve spring 12, but at the position A3 in FIG. 5, the second bolt 20 of the valve arm 15 in FIG. The exhaust valve 7 is held in a partially opened state by contacting the H3 valve-opening holding piston 51. That is, at the position A3 in FIG. 5, the curve changes from the solid curve X1 to the broken curve X3.

  When the valve opening holding period T4 in FIG. 5 ends with the exhaust valve 7 partially opened, the hydraulic oil outlet electromagnetic opening / closing valve 59 in FIG. Discharging from both orifices 53 and 54 starts, and the valve-opening holding piston 51 starts to descend from the height H3.

  The subsequent lowering of the valve-opening holding piston 51 is the same as in the case of the setting 1 and the action 1, and the description thereof is omitted.

  In the case where the valve closing operation of the exhaust valve 7 is delayed by the hydraulic valve opening and holding mechanism 50 as in the embodiment, the engine piston rises in the late stage of the exhaust stroke. The (lift amount) is set in a range where the engine piston and the exhaust valve do not interfere as much as possible.

  In addition, the hydraulic valve opening and holding mechanism 50 freely opens the valve closing start timing (position A1 in FIG. 5 and the like), the valve opening holding start timing (position A1 or A3 in FIG. 5 and the like), and the valve opening holding period (in FIG. 5). Period T2, T4, etc.) can be set, so that the maximum opening position (maximum lift amount) of the exhaust valve 7 by the valve drive cam mechanism 30 can be kept at the minimum required lift amount. That is, in FIG. 4, the valve curtain area S1 at the time of maximum valve opening and the substantial opening area S2 of the valve seat portion 8 can be suppressed to substantially coincide with each other. Incidentally, the valve curtain part area S1 is the area of the cylindrical part that connects the valve umbrella part and the valve seat part 8 when the valve is fully opened, and the valve seat part area S2 is the inner peripheral end of the valve seat part 8 and the valve It is a donut-shaped area surrounded by the shaft 7a. By setting the maximum lift amount so that both areas S1 and S2 are substantially the same as described above, the exhaust gas flowing in from the valve curtain portion can be substantially eliminated. It passes through the valve seat portion 8 and flows into the exhaust passage 2. That is, it is not necessary to set the maximum lift amount of the exhaust valve 7 unnecessarily high, and the exhaust valve 7 can be suppressed to a necessary minimum, thereby facilitating the design of the cam profile.

(Valve closed holding mechanism setting 3 and action 3)
To obtain the valve lift characteristic of the curve X1 in FIG. 5, the hydraulic oil in the hydraulic chamber 52 of the hydraulic valve opening and holding mechanism 50 is discharged, and the valve opening holding piston 51 is lowered to the minimum height H0 in FIG. Operate the engine while maintaining the condition.

  During engine operation, the hydraulic valve opening and holding mechanism 50 is not involved in the operation of the exhaust valve 7, so that the valve opening operation and the valve closing operation are performed only by the valve drive cam mechanism 30. That is, even during the valve return operation, the valve lift characteristic conforms to the curve X1 shown by the solid line in FIG.

[Second Embodiment of the Invention]
FIG. 6 shows valve lift characteristics when the present invention is applied to an internal combustion engine that can perform re-opening of the engine valve. As a premise for enabling re-opening, in FIG. 1, the cam 33 is formed with a re-opening cam peak 33b as shown by a virtual line, in addition to the original cam peak 33a for the exhaust stroke. The

  In addition to the function of changing the valve lift characteristic of the original exhaust valve as described in the first embodiment, the hydraulic valve opening holding mechanism 50 is shown by a broken line X7 in FIG. In addition, it has a function of extending the most enlightened period T7 by a desired length. That is, at the start of re-opening, the driving electromagnetic on-off valve 55 shown in FIG. 3 is opened to supply a predetermined amount of hydraulic oil to the hydraulic chamber 52, and the maximum opening degree of re-opening shown in FIG. The drive electromagnetic on-off valve 55 is closed at the open position A7, and after a predetermined period T7 has elapsed, the hydraulic oil outlet electromagnetic on-off valve 59 is opened to release the hydraulic oil from the hydraulic chamber 52 and the re-opening is completed. To do.

  Thus, by arbitrarily extending the re-opening period using the hydraulic valve opening holding mechanism 50, it is not necessary to form a complicated re-opening cam peak. That is, as the re-expansion cam crest 33b, it is only necessary to form a very thin cam crest that can perform the initial re-expansion lift (micro lift). During the re-expansion period, the hydraulic valve opening holding mechanism 50 is used. Can be extended to an arbitrary length.

[Third Embodiment of the Invention]
FIG. 7 shows the hydraulic oil outlet passage 69 of the hydraulic valve opening and holding mechanism 50 of one engine valve through the hydraulic valve opening and holding mechanism 50 of the engine valve in the same cylinder or the engine valve of another cylinder in the multi-cylinder engine. This is an example in which the hydraulic oil inlet passage 66 is connected.

  According to the configuration of FIG. 7, the valve-opening holding piston 51 of another hydraulic valve-opening holding mechanism 50 is moved using the hydraulic pressure generated by the lowering of the valve-opening holding piston 51 of one hydraulic valve-opening holding mechanism 50. The height can be raised slightly against the valve spring 12, and the re-opening operation can be performed regardless of the valve drive cam.

  In FIG. 7, the same components or members as those described in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted.

[Fourth Embodiment of the Invention]
FIG. 8 shows a hydraulic oil outlet passage of both hydraulic valve opening and holding mechanisms 50 and 50 in an internal combustion engine provided with a hydraulic valve opening and holding mechanism 50 in each of the intake valve arm 95 and the exhaust valve arm 15 in one cylinder C1. 69 and 69 are connected to a common electromagnetic on-off valve 59. According to the configuration shown in FIG. 8, the component cost can be reduced and the size can be reduced by using the electromagnetic on-off valve 59 in common. The structure of each hydraulic valve opening and holding mechanism 50 is the same as the structure described in FIG. Reference numeral 100 denotes a safety valve and 101 denotes a check valve.

  Even when the electromagnetic on-off valve 59 is shared as described above, the hydraulic valve-opening / holding mechanism on the exhaust valve side remains active while the intake valve-opening / holding mechanism 50 is operated when the intake valve is closed. 50 is kept in a lowered state. On the contrary, while the hydraulic valve opening holding mechanism 50 is operated when the exhaust valve is closed, the hydraulic valve opening holding mechanism on the intake valve side is lowered. Therefore, the use of the common electromagnetic on-off valve 59 does not hinder the operation of the intake and exhaust valves.

[Fifth Embodiment of the Invention]
FIG. 9 shows an example in which the hydraulic oil outlet passages 69 and 69 of the hydraulic valve opening and holding mechanisms 50 and 50 arranged in the cylinders C1 and C2 are connected to a common electromagnetic switching valve 59 in a multi-cylinder engine.

  According to the structure of FIG. 9, the common use of the electromagnetic on-off valve 59 can reduce the component cost and make it compact.

[Sixth Embodiment of the Invention]
FIG. 10 shows that notches 81 and 83 are formed in the valve-opening holding piston 51, and the valve-opening holding piston 51 is configured to be capable of adjusting the rotational position, thereby changing the area covering the opening of the variable orifice 53, Accordingly, the descending speed of the valve opening holding piston 51 can be arbitrarily adjusted.

  A semicircular first notch 81 is formed in the lower half of the valve-opening holding piston 51, and by rotating the valve-opening holding piston 51 from the state of FIG. 10 to the state of FIG. The opening area of the variable orifice 53 can be reduced to a desired size.

  The final annular notch 83 communicates with the first notch 81 through the communication passage 84, and the valve-opening holding piston 51 reaches the lowest position regardless of the rotational position of the valve-opening holding piston 51. The variable orifice 53 is configured to be fully opened when it is lowered.

  When the valve-opening holding piston 51 having the notches 81 and 83 as shown in FIGS. 10 to 12 is provided, the rotational position of the valve-opening holding piston 51 is adjusted according to the use conditions of the internal combustion engine. The valve closing speed can be arbitrarily adjusted, and when the engine valve is seated, the hydraulic oil in the hydraulic chamber 52 is completely discharged through the annular final notch 83, so that the engine valve is securely seated. Can be secured.

[Seventh Embodiment of the Invention]
FIG. 13 shows a modified example of the valve-opening holding piston 51 having a notch. In addition to the first notch 81 and the final annular notch 83 similar to those in FIG. Then, it is the example which formed the 2nd notch 82 from which the position of the circumferential direction differs.

  If the first and second cutouts 81 and 82 are formed in a two-stage format having different circumferential formation positions as in the structure of FIG. 13, the first step is performed in the downward stroke of the valve-opening holding piston 51. After decelerating at a constant speed by the notch 81, the area covering the variable orifice 53 by the second notch 82 can be further reduced.

[Eighth Embodiment of the Invention]
FIG. 14 shows still another example of the valve-opening holding piston 51 having a notch, and the shape of the circumferential edge of the notch 85 increases from the lower end of the valve-opening holding piston 51 upward. It is formed in an inclined shape (spiral shape) so as to spread to the side. That is, the deceleration amount increases as the valve-opening holding piston 51 descends.

[Other embodiments]
(1) It should be noted that the present invention can be applied to either an intake valve or an exhaust valve.

(2) In each of the above embodiments, an example in which the present invention is applied to an OHV type internal combustion engine has been described. However, the present invention can also be applied to an OHC type internal combustion engine.

1 is a longitudinal sectional view of an exhaust valve portion according to a first embodiment of an internal combustion engine including a variable valve device according to the present invention. It is an enlarged view of the arrow II part of FIG. It is an expanded vertical sectional view of a hydraulic valve opening holding mechanism. It is a longitudinal cross-sectional view which shows the exhaust valve part of a full open state. It is a valve lift characteristic line figure of the exhaust valve at the time of applying the present invention. It is a valve lift characteristic diagram of an exhaust valve at the time of applying the present invention for exhaust valve reopening. It is a longitudinal cross-sectional view of the hydraulic valve opening holding mechanism which shows another embodiment of this invention. It is the piping for hydraulic fluid which shows another embodiment of this invention. It is the piping for hydraulic fluid which shows another embodiment of this invention. It is an expansion longitudinal cross-sectional view of the valve opening holding | maintenance piston part which shows another embodiment of this invention. FIG. 11 is an enlarged longitudinal sectional view showing the same valve opening holding piston as FIG. 10 and showing another adjustment state. It is XII-XII sectional drawing of FIG. It is an expansion longitudinal cross-sectional view of the valve opening holding | maintenance piston part which shows another embodiment of this invention. It is an expansion longitudinal cross-sectional view of the valve opening holding | maintenance piston part which shows another embodiment of this invention. It is a lift characteristic diagram by a prior art example.

Explanation of symbols

1 Cylinder head 2 Exhaust passage 7 Exhaust valve (an example of an engine valve)
12 valve spring 15 valve arm 30 valve drive cam mechanism 31 push rod 32 tappet 33 cam 50 hydraulic valve opening holding mechanism 51 valve opening holding piston 52 hydraulic chamber 53 variable orifice (seat cushioning mechanism)
54 Fixed orifice (sitting cushioning mechanism)
55 Electromagnetic on-off valve for driving 56 Oil pump 59 Electromagnetic on-off valve for holding valve open 66 Hydraulic oil inlet passage (hydraulic oil inlet)
69 Hydraulic oil outlet passage (hydraulic oil discharge part)
81, 82, 83, 85 Notch (speed control mechanism)
95 valve arm

Claims (20)

In a variable valve operating apparatus for an internal combustion engine that opens and closes an intake or exhaust engine valve biased in a valve closing direction by a valve spring,
A valve drive cam mechanism;
A hydraulic valve opening holding mechanism having a valve opening holding piston that acts on the engine valve separately from the valve driving cam mechanism and delays the closing operation of the engine valve from the valve closing operation by the valve driving cam mechanism;
The engine valve is operated by the valve drive cam mechanism during the valve opening operation period, and the valve drive cam mechanism and the hydraulic valve opening holding mechanism are alternatively operated during the valve closing operation period. A variable valve operating device for an internal combustion engine. The variable valve operating apparatus for an internal combustion engine according to claim 1,
By controlling the operation of the valve opening holding piston, the valve opening holding height and the valve opening holding period of the engine valve when the valve opening holding mechanism is selected can be continuously changed. Variable valve gear. The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2,
A variable valve operating apparatus for an internal combustion engine, wherein the valve closing start timing of the engine valve when the hydraulic valve opening holding mechanism is selected can be changed by controlling the operation of the valve opening holding piston. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The valve drive cam mechanism is linked to the engine valve via the tappet, push rod and valve arm in this order,
Push rod, together with the coupling portion which is integrally fixed to the push rod relative moveably coupled to the push rod moving direction relative Ben'ude pressed against the cam surface of the valve drive cam by the auxiliary spring, and the fittings A variable valve operating apparatus for an internal combustion engine, wherein a concave portion into which a bolt provided on a valve arm is inserted is formed in the part as a drop-off preventing mechanism . The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
An internal combustion engine characterized in that a hydraulic valve opening holding mechanism has a seating buffer mechanism that limits a seating speed of an engine valve when the valve opening holding state at the time of selecting the hydraulic valve opening holding mechanism is cancelled. Variable valve gear. The variable valve operating apparatus for an internal combustion engine according to claim 5,
A variable valve operating apparatus for an internal combustion engine, characterized in that a variable orifice is provided as a seating buffer mechanism at a hydraulic oil outlet of the hydraulic chamber. The variable valve operating apparatus for an internal combustion engine according to claim 6,
As a seating buffer mechanism, a variable orifice is provided at the hydraulic oil outlet of the hydraulic chamber,
A variable valve operating apparatus for an internal combustion engine, characterized in that a hydraulic oil inlet having an electromagnetic on-off valve is opened at the bottom of a hydraulic chamber, and the electromagnetic on-off valve is opened at the end of the lowering operation of the valve-opening holding piston. . The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The variable valve operating apparatus for an internal combustion engine, wherein the valve-opening holding piston is disposed so as to protrude upward from the hydraulic chamber. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
A variable valve operating apparatus for an internal combustion engine, comprising a safety valve that opens when the hydraulic oil pressure in the hydraulic chamber exceeds a predetermined value and opens the hydraulic oil in the hydraulic chamber. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
A variable valve operating apparatus for an internal combustion engine, wherein a hydraulic valve opening and holding mechanism separate from the valve drive cam mechanism is detachably attached to a main body of the internal combustion engine provided with the valve drive cam mechanism. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The hydraulic oil outlet of the hydraulic chamber communicates with the hydraulic oil inlet of the hydraulic chamber of the hydraulic valve opening and holding mechanism for other engine valves, and is discharged from the hydraulic chamber when the valve opening holding by the hydraulic valve opening and holding mechanism is released. A variable valve operating apparatus for an internal combustion engine, wherein the hydraulic oil to be supplied is supplied to a hydraulic chamber of the other hydraulic valve opening and holding mechanism. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The maximum height of the engine valve determined by the cam surface of the valve drive cam mechanism is controlled so that the valve curtain area is substantially the same as the flow cross-sectional area of the valve seat portion. Valve device. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
A variable valve operating apparatus for an internal combustion engine, characterized in that the valve opening and holding start timing by the hydraulic valve opening and holding mechanism is set to a valve height at which the engine valve for exhaust and the engine piston do not interfere with each other. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
On the cam surface of the valve drive cam mechanism, in addition to the normal cam mountain for opening and closing the engine valve, a cam mountain for re-opening is formed,
A variable valve operating apparatus for an internal combustion engine, wherein the re-opening period is variable by a hydraulic valve opening holding mechanism. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
A valve drive cam mechanism and a hydraulic valve opening and holding mechanism are provided for an intake engine valve and an exhaust engine valve in one cylinder,
A variable valve operating apparatus for an internal combustion engine, wherein a common electromagnetic on-off valve opens and closes a hydraulic oil discharge part of each hydraulic valve opening and holding mechanism. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The internal combustion engine has a plurality of cylinders,
A variable valve operating apparatus for an internal combustion engine, characterized in that a common electromagnetic on-off valve opens and closes a hydraulic oil discharge part of a hydraulic valve-opening holding mechanism of each cylinder. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3,
The hydraulic valve-opening holding mechanism has a valve-closing speed adjusting mechanism capable of adjusting a valve-closing speed. The variable valve operating apparatus for an internal combustion engine according to claim 17,
The valve closing speed adjusting mechanism is composed of a notch formed in the valve opening holding piston and a variable orifice that opens to the hydraulic chamber, and the notch is opened by opening the variable orifice by rotating the valve opening holding piston. A variable valve operating apparatus for an internal combustion engine, characterized in that an area covering the portion can be adjusted. The variable valve operating apparatus for an internal combustion engine according to claim 17,
A variable valve operating apparatus for an internal combustion engine, wherein a plurality of notches formed in the valve opening holding piston are formed in a moving direction of the valve opening holding piston. The variable valve operating apparatus for an internal combustion engine according to claim 19,
The variable valve operating device for an internal combustion engine, wherein the plurality of notches are arranged so as to sequentially decrease the valve closing speed when the valve closing operation is performed after releasing the valve holding.

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