JP3577932B2 - Variable valve gear - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a variable valve operating device that varies valve characteristics such as a valve lift and a working angle of an internal combustion engine, and in particular, includes a plurality of cams having different cam characteristics and selects a cam that opens and closes an engine valve. The present invention relates to a variable valve actuation device of a type in which valve characteristics are made variable by selectively switching.
[0002]
[Prior art]
2. Description of the Related Art A variable valve apparatus that changes valve characteristics such as the opening / closing timing of an engine valve and its lift amount in accordance with the operating state of an internal combustion engine has been proposed and put into practical use. As such a variable valve device, for example, Japanese Patent Publication No. Hei 4-2767 discloses a plurality of types of cams having different cam characteristics for each cylinder and selectively switching a cam for driving an engine valve to open and close. A variable valve operating device including a variable valve operating mechanism that makes variable is described.
[0003]
Such a variable valve operating device will be described with reference to FIGS.
FIG. 9 shows an aspect of the variable valve mechanism of the variable valve device at the time of low-speed operation of the engine, and FIG. 10 shows an aspect of the variable valve mechanism of the device at the time of high-speed operation of the engine. The internal combustion engine provided with the variable valve apparatus is of a double overhead camshaft (DOHC) type having two camshafts for intake and exhaust, and has two intake valves and two exhaust valves for each cylinder. It has a four-valve configuration.
[0004]
The camshaft of the internal combustion engine provided with the variable valve device includes two low-speed cams for each cylinder and a high-speed cam provided between the low-speed cams. The high-speed cam has a cam profile with a higher lift portion in order to increase the opening / closing timing of the engine valve and the lift amount of the engine valve compared to the low-speed cam. The variable valve mechanism 100 for opening and closing the engine valve based on the low-speed cam and the high-speed cam is rotatably mounted on the rocker shaft 6 as shown in FIGS. A first rocker arm 103 and a second rocker arm 104 that are oscillated by the cam for use, and a mid rocker arm 105 that is also rotatably mounted on the rocker shaft 6 and oscillated by the high-speed cam. In addition, tappet screws 109 that are in contact with the upper ends of the engine valves 9 are provided at the distal ends of the first and second rocker arms 103 and 104.
[0005]
Further, accommodation holes 106 and 107 and an accommodation hole 108 extending in parallel with the rocker shaft 6 are formed in each of the rocker arms 103 to 105. The first and second switching pins 110 and 111 and the regulating pin 112 are loosely fitted in the accommodation holes 106 and 107 and the accommodation hole 108 so as to be slidable in the axial direction. The restriction pin 112 is urged toward the mid rocker arm 105 by a coil spring 113 and presses the first and second switching pins 110 and 111.
[0006]
The space 114 between one end of the first switching pin 110 and the closed end of the housing hole 106 is a hydraulic chamber. The hydraulic chamber 114 communicates with a rocker arm oil passage 116 formed in the first rocker arm 103. The rocker arm oil passage 116 extends through the annular oil passage 115 formed in the rocker shaft 6 at the sliding contact portion with the first rocker arm 103 so as to extend inside the rocker shaft 6 in the axial direction. It communicates with the provided rocker shaft oil passage 31.
[0007]
Here, when hydraulic oil (usually lubricating oil of an internal combustion engine is not supplied) into the hydraulic chamber 114, each of the rocker arms 103 to 105 can freely swing in the mode shown in FIG. It has become. That is, at this time, the mid rocker arm 105 swung by the high-speed cam having a higher lift portion is separated from the first and second rocker arms 103 and 104, so that the mid rocker arm 105 is swung in a so-called idle state. Accordingly, each engine valve 9 is swung by the low speed cam through the first and second rocker arms 103 and 104, respectively.
[0008]
On the other hand, when oil is supplied to the hydraulic chamber 114 through the oil passages 23, 115, 116, the first and second switching pins 110, 111 and the regulating pin 112 are moved by the oil pressure as shown in FIG. Move to the second rocker arm 104 side against the urging force of the coil spring 113. By this movement, the first and second switching pins 110 and 111 are sandwiched between the accommodation holes 106 and 108 and between the accommodation holes 107 and 108, respectively, and the rocker arms 103 to 105 are connected. And swings together. That is, at this time, the rocker arms 103 to 105 and the engine valve 9 are driven by the high-speed cam having a higher lift portion.
[0009]
Next, the configuration of a hydraulic circuit that supplies oil to the variable valve mechanism 100 in the variable valve apparatus will be described with reference to FIG. In FIG. 11, a cam 101 is the low-speed cam, and a cam 102 is the high-speed cam. The rocker arms 103 to 105 that constitute the variable valve mechanism 100 are respectively opposed to the cams 101 and 102.
[0010]
In the hydraulic circuit shown in FIG. 11, the oil pump 25 is a part that sucks the oil in the oil pan 24 and pressurizes and discharges the oil to the hydraulic switching valve 117 via the oil supply path 124. The hydraulic switching valve 117 is an electromagnetic three-port directional control valve. The first port 118 of the hydraulic switching valve 117 is an oil inlet and is connected to the oil supply path 124. The third port 120 is connected to a first lubricating oil passage 126 that supplies lubricating oil to the low-speed cam 101. The second port 119 is connected to an oil passage 125 that supplies oil to the variable valve operating device 100 via a rocker shaft oil passage 31 formed in the rocker shaft 6. A second lubricating oil passage 128 for supplying lubricating oil to the high-speed cam 102 and the bearing of the camshaft 1 is connected to the rear end of the rocker shaft oil passage 31 via an orifice 127. .
[0011]
The hydraulic switching valve 117 has a guide hole 130 formed therein, and a spool 121 is slidably inserted therein. The spool 121 is urged downward by the urging force of the coil spring 122, and is attracted to the position shown in FIG. 11 against the urging force when the solenoid 123 is excited. Is done. In this state, the first port 118 and the second port 119 are connected. When the solenoid 123 is demagnetized, the spool 121 moves downward in FIG. In this state, the first port 118 and the third port 120 are connected. At this time, the small-diameter bypass passage 129 formed in the spool 121 also communicates with the first port 118 and the second port 119.
[0012]
That is, in such an apparatus, when the internal combustion engine is operating at a high speed, the solenoid 123 is excited, and the oil is supplied to the variable valve mechanism 100 via the first port 118 and the second port 119. The rocker arms 103 to 105 of the variable valve mechanism 100 are connected by the hydraulic pressure, and the engine valve 9 is driven to open and close by the high-speed cam 102 (see FIG. 10). At this time, a small amount of oil is also supplied to the second lubricating oil passage 128 via the orifice 127, and the high-speed cam 102 and the bearing of the camshaft 1 are lubricated.
[0013]
On the other hand, during low-speed operation, the solenoid 123 is demagnetized, and oil is supplied to the low-speed cam 101 via the first port 118, the third port 120, and the first lubricating oil passage 126. At the same time, the first port 118 and the second port 119 communicate with each other through the bypass passage 129, and a small amount of hydraulic oil is supplied to the oil passage 125. At this time, the oil supplied to the oil passage 125 is supplied to the second lubricating oil passage 128 via the orifice 127, and the lubrication of the high-speed cam 102 and the bearing of the camshaft 1 is maintained. However, at this time, since the amount of oil supplied to the oil passage 125 is small, the hydraulic pressure in the hydraulic chamber 114 of the variable valve mechanism 100 is reduced against the urging force of the coil spring 113 and the pins 110, 111, 112 Not as high as you move. Accordingly, each of the rocker arms 103 to 105 swings independently, and the engine valve 9 is driven to open and close by the low-speed cam 101 (see FIG. 9).
[0014]
As described above, in this hydraulic circuit configuration, a small amount of oil is continuously supplied through the bypass passage 129 even when the hydraulic pressure is not supplied to the variable valve mechanism 100, so that the bearings of the cams 101 and 102 and the camshaft 1 are provided. The lubrication of the lubrication parts such as the parts is maintained. In addition, by maintaining the fluidity of the oil in the oil passages 31 and 125 for supplying oil to the mechanism 100, the responsiveness at the time of cam switching is improved.
[0015]
[Problems to be solved by the invention]
By the way, in order to improve the responsiveness at the time of cam switching, the pins 110, 111, 112 move into the hydraulic chamber 114 against the oil pressure at which the cam switching operation is performed, that is, against the urging force of the coil spring 113. It is desirable to always provide the highest possible hydraulic pressure below the hydraulic pressure. However, in the conventional variable valve apparatus that supplies hydraulic oil to the variable valve mechanism through the hydraulic circuit having the above-described configuration, the amount of hydraulic oil supplied through the bypass passage 129 is small. The hydraulic pressure in the hydraulic chamber 114 cannot be so high. For this reason, it was not possible to ensure sufficient responsiveness when switching cams.
[0016]
On the other hand, in the case of the conventional variable valve apparatus, it is possible to increase the hydraulic pressure supplied to the hydraulic chamber 114 before the cam switching operation by increasing the diameter of the bypass passage 129. . However, when the diameter of the bypass passage 129 is simply enlarged, the cam switching is not always performed in a predetermined mode.
[0017]
That is, the hydraulic oil supplied from the oil pump 25 is also supplied to the lubricating portion of the internal combustion engine, other hydraulic control mechanisms, and the like. A sudden change may also occur in the oil pressure of the oil to be discharged. In this respect, in the configuration in which the hydraulic oil is supplied via the bypass passage 129 even when the hydraulic pressure is not supplied as described above, the hydraulic oil is directly affected by such a fluctuation in the hydraulic pressure, and the hydraulic pressure previously provided in the hydraulic chamber 114 is increased. In this case, there is a concern that the pins 110, 111, and 112 may be erroneously moved due to the oil pressure fluctuation, and erroneous cam switching may be performed.
[0018]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable valve operating device capable of reliably improving the responsiveness of a variable valve operating mechanism while avoiding occurrence of a malfunction. Is to do.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is:With two hydraulic pressure control mechanisms that are individually hydraulically controlledBased on hydraulic pressure control3 for low speed / medium speed / high speedA variable valve mechanism including a variable valve mechanism for selectively switching a cam for opening and closing an engine valve from among various kinds of cams, and a support shaft rotatably supporting the variable valve mechanism. Hydraulic fluid for hydraulically controlling the valve mechanism is supplied through a hydraulic fluid passage formed in the support shaft, and the support shaft is driven by the variable valve mechanism and the hydraulic fluid in the support shaft based on its rotation. Equipped with an opening communicating with or blocking the passageAn opening communicating with the two hydraulic pressure control mechanisms and a hydraulic fluid passage in the support shaft is communicated with each of the hydraulic pressure control mechanisms at a different support shaft rotation phase; A groove extending in the circumferential direction of the support shaft from an opening for selecting a medium speed cam is formed on the peripheral surface of the support shaft, and the groove is an opening for selecting a high speed cam in the circumferential direction of the support shaft. Stretched to the position corresponding to the partThat is the gist.
[0020]
According to this configuration, the hydraulic pressure of the variable valve mechanism can be controlled by rotating the support shaft. For this reason, the hydraulic fluid passage formed in the support shaft can always be filled with high-pressure hydraulic fluid, and the hydraulic fluid required at the time of the cam switching operation is used to rotate the support shaft. This will allow you to resupply instantly. This means that the time required to increase the hydraulic pressure in the variable valve mechanism to the hydraulic pressure required for the cam switching operation is reduced, and that the responsiveness of the variable valve mechanism is improved. Further, unless the support shaft rotates in a manner communicating with the supply path of the hydraulic oil, the supply of the hydraulic fluid to the variable valve mechanism is not performed, so that a malfunction of the variable valve mechanism due to the fluctuation of the hydraulic pressure occurs. Is also suitably prevented.
Further, according to the above configuration, the rotation of the support shaft is performed with respect to a variable valve mechanism that includes two hydraulic pressure control mechanisms and selects a cam that opens and closes the engine valve from among three types of cams. It is possible to adopt a mechanism for switching the supply of the working fluid by movement.
In addition, during the period from the rotation phase at the time of the engine medium speed operation to the rotation phase at the time of the engine high speed operation, the support shaft is turned through the groove to select the cam for the medium speed through the groove. The hydraulic oil will continue to be supplied. Accordingly, the supply of the hydraulic oil is temporarily interrupted during the switching from the medium speed cam to the high speed cam, and the situation that the engine valve is opened and closed by the low speed cam does not occur.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of the present invention will be described. The variable valve operating device according to the present embodiment is configured as a device capable of switching hydraulic pressure supply to the variable valve operating mechanism based on rotation of a rocker shaft on which the variable valve operating mechanism is mounted.
[0028]
First, the configuration of the variable valve mechanism provided in the variable valve apparatus of the present embodiment will be described with reference to FIGS. FIG. 1 shows a perspective view showing a part of the variable valve mechanism 5 and a part of the camshaft 1, and FIGS. 2 and 3 show sectional structures of a hydraulic lock mechanism provided in the variable valve mechanism 5. I have.
[0029]
The camshaft 1 is provided with three types of cams having different cam profiles, that is, a low-speed cam 2, a medium-speed cam 3, and a high-speed cam 4. These cams are formed in such a manner that the low-speed cam 2, the medium-speed cam 3, and the high-speed cam 4 have a cam profile such that the opening / closing timing and the lift amount of the engine valve 9 driven by the cams are increased. ing.
[0030]
Below the camshaft 1, a rocker shaft 6 is provided in parallel with the shaft 1. A rocker arm 7 is rotatably mounted on the rocker shaft 6. The variable valve mechanism 5 is configured around the rocker arm 7. The variable valve mechanism 5 includes a pair of movable followers respectively corresponding to the medium speed cam 3 and the high speed cam 4, and a hydraulic lock mechanism for restricting or releasing the sliding of the movable followers. Have been. As described above, in the variable valve mechanism 5, members which are provided symmetrically on the medium speed cam 3 side and the high speed cam 4 side and have basically the same functions are denoted by the same reference numerals. In particular, a distinction is made by attaching "a" to the end of the member on the side of the medium speed cam 3 and attaching "b" to the end of the member on the side of the high speed cam 4. Further, in the following description, when the identifiers “a” and “b” at the end of the reference numerals of these members are omitted, unless otherwise specified, both the medium speed cam 3 side and the high speed cam 4 side are used. Shall be shown.
[0031]
The rocker arm 7 has its base end rotatably supported by the rocker shaft 6. An arm 8 is formed to extend forward from the tip side of the rocker arm 7, and the tip of the arm 8 can be brought into contact with the head of the engine valve 9.
[0032]
A roller follower 10 is rotatably supported at the center of the upper surface of the rocker arm 7. The roller follower 10 is rotatable with the low-speed cam 2. Further, on the upper surface of the rocker arm 7, on both sides of the roller follower 10, guide holes 11a and 11b having a circular cross section are formed vertically downward. Movable followers 12a and 12b each having a substantially cylindrical shape are slidably inserted into the guide holes 11a and 11b. Of these two movable followers, one movable follower 12a is a medium-speed movable follower that is slid by the medium-speed cam 3, and the other movable follower 12b is a high-speed movable follower that is slid by the high-speed cam 4. It is a movable follower. As shown in FIGS. 2 and 3, these movable followers 12a and 12b form slippers 13a and 13b having a rectangular cross section provided on their heads and cylindrical shapes so that they can be inserted into the guide holes 11a and 11b. It consists of legs. The upper end surfaces of the slippers 13a and 13b are arcuate surfaces in the manner shown in FIGS. 3 and 4, and can be in sliding contact with the medium speed cam 3 or the high speed cam 4. A hole having a circular cross section is formed in the leg of each of the movable followers 12a and 12b, and a lost motion spring 14 is provided inside the hole. The movable followers 12a and 12b are urged by the lost motion spring 14 toward the medium speed cam 3 or the high speed cam 4 (FIG. 1). The spring force of the lost motion spring 14 is set sufficiently smaller than the spring force of the valve spring provided on the engine valve 9.
[0033]
On the other hand, as shown in FIGS. 1 to 3, cylinder holes 15 a and 15 b having a circular cross section orthogonal to the guide holes 11 a and 11 b are formed below the rocker arm 7 from the tip end side of the rocker arm 7. Side grooves 16a and 16b having a semicircular cross section are formed on both sides of the cylinder holes 15a and 15b in parallel with the cylinder holes 15a and 15b.
[0034]
Next, a hydraulic lock mechanism (hereinafter, simply referred to as a "lock mechanism") disposed in the cylinder holes 15a and 15b and the side grooves 16a and 16b to limit or allow the sliding of the movable followers 12a and 12b. Will be described in detail with reference to FIGS.
[0035]
As shown in FIGS. 2 and 3, a cylindrical hydraulic piston 17 is slidably inserted into the cylinder hole 15, and a semi-cylindrical side 18 is slidably inserted into the side groove 16. The hydraulic piston 17 and the side 18 are integrally assembled, and can slide integrally between the position shown in FIG. 2 and the position shown in FIG.
[0036]
The inner surface of the tip of the side 18 is an inclined flat surface, and when located at the position shown in FIG. 2, interference with the movable follower 12 is avoided and sliding of the movable follower 12 is allowed. I can do it. A flat surface is formed on the upper surface of the tip of the side 18 so that the bottom surface of the movable follower 12 can be supported when it is at the position shown in FIG. That is, when the hydraulic piston 17 and the side 18 are located at the positions shown in FIG. 2, the movable follower 12 can freely slide in the guide hole 11. On the other hand, when the movable follower 12 is located at the position shown in FIG. 3, the bottom surface of the leg of the movable follower 12 is supported in contact with a plane formed on the upper surface of the side 18, and the movable follower 12 Sliding is limited.
[0037]
In addition, a groove having a rectangular cross section is formed on the side of the base of the rocker arm 7 on the leg of the movable follower 12. A spring receiving member 21 is slidably inserted into this groove. A coil spring 19 is disposed between the spring receiving member 21 and the end face of the hydraulic piston 17 on the tip side. The coil spring 19 urges the spring receiving member 21 toward the movable follower 12 and also urges the hydraulic piston 17 toward the inner bottom surface of the cylinder hole 15, that is, toward the base end of the rocker arm 7.
[0038]
Here, the space 22 between the inner bottom surface of the cylinder hole 15 and the proximal end surface of the hydraulic piston 17 is a hydraulic chamber. The hydraulic chamber 22 communicates with a rocker arm oil passage 23 formed in the rocker arm 7. The hydraulic oil is supplied into the hydraulic chamber 22 through the rocker arm oil passage 23. Normally, lubricating oil for an internal combustion engine is used as the operating oil.
[0039]
In the variable valve mechanism 5 configured as described above, when the hydraulic pressure of the hydraulic oil supplied into the hydraulic chamber 22 becomes higher than a certain level, the hydraulic piston 17 and the side 18 resist the urging force of the coil spring 19. 2 from the position shown in FIG. 2 to the position shown in FIG. 3 to limit the sliding of the movable follower 12. The movable follower 12, whose sliding is thus restricted, swings integrally with the rocker arm 7.
[0040]
On the other hand, when the hydraulic pressure in the hydraulic chamber 22 decreases to a certain level or less, the hydraulic piston 17 moves from the position shown in FIG. 3 to the position shown in FIG. The restriction on the sliding of the follower 12 is released. The movable follower 12 that has become freely slidable in this manner is separated from the rocker arm 7, and so-called slidably slides.
[0041]
In the present embodiment, the guide hole 11 is formed by the hydraulic piston 17, the side 18, the coil spring 19, the spring receiving member 21, and the hydraulic chamber 22 provided in the cylinder hole 15 or the side groove 16. A lock mechanism for restricting or releasing the sliding of the movable follower 12 in the inside is configured.
[0042]
Next, the configuration of a hydraulic circuit that supplies hydraulic oil to the lock mechanism of the variable valve mechanism 5 will be described with reference to FIG.
The oil pump 25 sucks the lubricating oil in the oil pan 24 and actually pressurizes and discharges the lubricating oil to an oil supply passage 26 formed inside a cylinder head or a cylinder block of the internal combustion engine. The oil supply path 26 is connected to a hydraulic oil supply path 28 for supplying lubricating oil as hydraulic oil to the variable valve mechanism 5 and a lubricating part such as a bearing of the camshaft 1 and each of the cams 2 to 4. On the other hand, it branches to a lubricating oil passage 27 for supplying lubricating oil.
[0043]
The hydraulic oil supply passage 28 passes through the bearing 29 of the rocker shaft 6 and communicates with a sliding contact between the rocker shaft 6 and the coaxial receiver 29. The rocker shaft 6 is rotatably supported by the bearing portion 29. Further, in the rocker shaft 6, a rocker shaft oil passage 31 for supplying hydraulic oil to the lock mechanisms of the respective variable valve mechanisms 5 is formed along the axis of the rocker shaft 6. The rocker shaft oil passage 31 communicates with the hydraulic oil supply passage 28 through an oil supply port 30 formed in a portion of the rocker shaft 6 that is in sliding contact with the bearing 29.
[0044]
On the other hand, the front ends of the rocker arm oil passages 23a and 23b communicated with the hydraulic chambers 22a and 22b of the variable valve mechanism 5 described above extend to a sliding portion between the rocker arm 7 and the rocker shaft 6, and both rocker arm oil passages are provided. Both 23a and 23b are opened in the same direction. A sliding portion of the rocker shaft 6 that contacts the rocker arm 7 has a medium speed opening 32 that can communicate with the medium speed rocker arm oil passage 23a, and a high speed opening that can communicate with the high speed rocker arm oil passage 23b. A portion 34 is formed. The rocker shaft oil passage 31 and the respective rocker arm oil passages 23a and 23b can communicate with each other through the openings 32 and 34. The medium-speed opening 32 and the high-speed opening 34 have a structure in which the rocker shaft 6 is rotated to communicate with or be disconnected from the medium-speed rocker arm oil passage 23a or the high-speed rocker arm oil passage 23b. Has become. The middle speed side opening 32 and the high speed side opening 34 are formed at positions sufficiently separated from each other in the circumferential direction around the axis of the rocker shaft 6. Accordingly, with the rocker arm 7 swinging, the communication between the medium-speed rocker arm oil passage 23a and the medium-speed opening 32 and the communication between the high-speed rocker arm oil passage 23b and the high-speed opening 34 are not simultaneously performed. It has a structure (to be described later with reference to FIGS. 5 to 7). A groove 33 is formed on the peripheral surface of the rocker shaft 6 so as to extend from the middle speed side opening 32 in the circumferential direction of the rocker shaft 6. The groove 33 extends in the circumferential direction of the rocker shaft 6 to a position corresponding to the position where the high-speed opening 34 is provided.
[0045]
Next, a rocker shaft drive mechanism for rotating the rocker shaft 6 will be described with reference to FIG.
A gear 37 is mounted on the rocker shaft 6 so as to be integrally rotatable. In the vicinity of the rocker shaft 6, a motor (for example, a step motor) 35 that is driven and controlled by an electronic control unit (ECU) 39 that performs various controls of the internal combustion engine is provided. A gear 36 is also mounted on the output shaft of the motor 35 so as to be integrally rotatable, and meshes with a gear 37 mounted on the rocker shaft 6. The rotation of the output shaft of the motor 35 is transmitted to the rocker shaft 6 via gears 36 and 37. Therefore, by controlling the rotation of the motor 35 by the ECU 39, the rotation phase of the rocker shaft 6 can be freely set.
[0046]
Next, the operation of the above-described variable valve apparatus will be described with reference to FIGS. 5 to 7 are cross-sectional views of the rocker shaft 6 and its vicinity at the axial position where the openings 32 and 34 are provided. FIG. FIG. 7 shows the state at the time of high-speed operation and the state at the time of high-speed operation of the engine.
[0047]
During low-speed operation of the engine, as shown in FIGS. 5A and 5B, the rocker shaft 6 is rotated in a rotation phase in which neither of the openings 32 and 34 communicate with the rocker arm oil passages 23a and 23b. Therefore, since the hydraulic oil is not supplied to the lock mechanisms on the medium speed side and the high speed side, the movable followers 12a and 12b can freely slide in the guide holes 11a and 11b. In this manner, both the medium-speed side and the high-speed side movable followers 12a and 12b are in a state of sliding free, so to speak, and the rocker arm 7 is swung by the low-speed cam 2.
[0048]
In addition, at the time of the engine middle speed operation, as shown in FIG. 6A, the rocker shaft 6 is rotated in a rotation phase in which the middle speed side opening 32 and the middle speed side rocker arm oil passage 23a communicate. Thus, the hydraulic oil is supplied only to the lock mechanism on the medium speed side, and the sliding of the movable follower 12a on the medium speed side in the guide hole 11a is restricted. At this time, as shown in FIG. 6B, since the hydraulic oil is not supplied to the high-speed side lock mechanism, the high-speed side movable follower 12b is in a state of being slid so to speak. Therefore, the rocker arm 7 swings based on the rotation and pressing of the medium speed cam 3 having a higher lift portion.
[0049]
Then, during the high-speed operation of the engine, as shown in FIG. 7B, the rocker shaft 6 is rotated in a rotation phase in which the high-speed opening 34 and the high-speed rocker arm oil passage 23b communicate with each other. At this time, as shown in FIG. 7A, the hydraulic oil is also supplied to the medium speed side rocker arm oil passage 23a via the medium speed side opening 32 and the groove 33. In this manner, the hydraulic oil is supplied to both of the lock mechanisms on the medium speed side and the high speed side, and the sliding in the guide holes 11a and 11b is limited for both the movable followers 12a and 12b. Therefore, the rocker arm 6 is swung based on the rotation and pressing of the high-speed cam 4 having the highest lift.
[0050]
The rotation speed of the rocker shaft 6 from the rotation phase at the time of the engine middle speed operation shown in FIG. 6 to the rotation phase at the time of the engine high speed operation shown in FIG. The hydraulic oil continues to be supplied to the side lock mechanism. Accordingly, a structure in which the supply of the hydraulic oil to the lock mechanism is temporarily interrupted during the switching from the middle speed cam 3 to the high speed cam 4 and the rocker arm 7 is not swung by the low speed cam 2 does not occur. Has become. In particular, when the cam for swinging the rocker arm 7 is switched to the low-speed cam 2 at a stroke during the switching operation from the high-speed cam 4 to the medium-speed cam 3, the amount of intake air introduced into the combustion chamber of the internal combustion engine is reduced. Alternatively, there is a concern that the amount of exhaust gas discharged from the combustion chamber may fluctuate rapidly and adversely affect the operation of the internal combustion engine. Further, since the cam drive resistance against the rotation of the camshaft 1 also fluctuates rapidly, the camshaft 1 and its drive system may be adversely affected. In the present embodiment, such a problem is prevented by a simple structure in which only the groove 33 is provided.
[0051]
By the way, conventionally, the switching of the supply of the hydraulic oil to the variable valve mechanism as described above has been performed by a hydraulic switching valve provided in a cylinder head or the like. In such a configuration, the variable valve mechanism is configured to communicate with the hydraulic switching valve via an oil passage formed in the cylinder head and the rocker shaft. Even when the supply of the hydraulic oil is started, the hydraulic oil of a sufficient pressure is supplied to the variable valve mechanism until the hydraulic oil of a sufficient pressure is filled in the oil passage reaching the variable valve mechanism. I can't. Therefore, there is a delay in starting the cam switching operation. In this regard, in the present embodiment, the high-pressure hydraulic oil is always filled in the rocker shaft oil passage 31 in the rocker shaft 6 to which the variable valve mechanism 5 is mounted. Therefore, the cam switching operation can be performed only by filling the rocker arm oil passage 23 and the hydraulic chamber 22 with hydraulic oil having a sufficient pressure, and the time until the completion of the cam switching operation can be greatly reduced.
[0052]
In the present embodiment, the supply of the hydraulic oil to the variable valve mechanism 5 is not performed unless the rocker shaft 6 is rotated in the mode shown in FIG. 6 or FIG. Does not cause the variable valve mechanism 5 to malfunction.
[0053]
Conventionally, in a variable valve apparatus having two or more lock mechanisms and a variable valve mechanism for hydraulically controlling each of the lock mechanisms, a different hydraulic oil supply is provided for each lock mechanism. A route was needed. Therefore, the rocker shaft oil passage 31 in the rocker shaft 6 must be divided into a plurality of oil passages, and the structure of the oil passage has been complicated. In this regard, in the present embodiment, even when a plurality of lock mechanisms are provided as described above, the hydraulic supply system path to the variable valve mechanism 5 can be unified, and the structure can be simplified. I can do it.
[0054]
Normally, lubrication of the sliding portion between the rocker shaft 6 and the variable valve mechanism 5 is performed by the hydraulic oil in the rocker shaft oil passage 31 leaking into the clearance of the sliding portion. In the embodiment, since the hydraulic oil is always filled in the rocker shaft oil passage 31, it is possible to always maintain the lubrication of such a sliding portion.
[0055]
As described above, according to the present embodiment, the following effects can be obtained.
(1) Since the supply of the hydraulic oil to the variable valve mechanism 5 is switched by the rotation of the rocker shaft 6, the volume of a portion that needs to be filled with sufficient hydraulic oil at the time of the cam switching operation is greatly increased. Can be reduced. Therefore, the cam switching time can be reduced, and the responsiveness of the variable valve mechanism 5 can be greatly improved.
[0056]
(2) The hydraulic oil is not supplied to the variable valve mechanism 5 unless the rocker shaft 6 is rotated in such a manner that the oil supply ports 32 and 34 communicate with the rocker arm oil passages 23a and 23b. The variable valve mechanism 5 does not malfunction due to the fluctuation of the hydraulic pressure.
[0057]
(3) By providing the groove 33, when switching between the medium speed cam 3 and the high speed cam 4, the supply of the hydraulic fluid to the lock mechanism is temporarily cut off, and the rocker arm 7 is rocked by the low speed cam 2. The occurrence of a situation can be prevented.
[0058]
(4) It is possible to unify the hydraulic supply system path to the variable valve mechanism 5, and to simplify the structure of the hydraulic circuit.
(5) Lubrication of the sliding portion between the rocker shaft 6 and the variable valve mechanism 5 can be constantly maintained.
[0059]
The present embodiment may be modified as follows.
In the present embodiment, the groove 33 is provided on the rocker shaft 6 side. However, the groove 33 may be provided on the rocker arm 7 side.
[0060]
In the above-described embodiment, the rocker shaft 6 is rotated by using, for example, a step motor as the motor 35. However, other than that, for example, a detector for detecting the rotation phase of the rocker shaft 6 or each rotation phase may be used. A configuration may be provided in which a corresponding limit switch or the like is provided to manage the rotation of the motor 35, or a configuration in which the motor 35 is used as a servomotor.
[0061]
The drive mechanism of the rocker shaft 6 is not limited to the electric mechanism as described above, but may be any mechanism such as a hydraulic type, a pneumatic type, a mechanical type, etc., as long as the actuator can rotate the rocker shaft 6. May be adopted.
[0062]
In this embodiment, the variable valve mechanism 5 that switches between three types of cams, that is, two for low speed, three for medium speed, and four for high speed, has been described. The mechanism further includes, for example, one movable follower and one lock mechanism each, and a variable valve mechanism that switches between two types of cams, and three or more movable followers and a lock mechanism, and four or more types. The present invention can be similarly applied to a variable valve mechanism that switches the cam.
[0063]
(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described. The variable valve operating device according to the present embodiment provides a check valve in the hydraulic oil discharging path, thereby constantly increasing the hydraulic pressure of the operating oil in the variable valve operating mechanism and improving the responsiveness during the cam switching operation. It is configured as a possible variable valve train.
[0064]
In this embodiment, for convenience, as a variable valve mechanism, a movable follower and the lock mechanism are provided one by one, and a mechanism for switching between two kinds of cams, the low-speed cam 2 and the high-speed cam 4, is provided. Suppose.
[0065]
First, the configuration of the hydraulic circuit of the variable valve apparatus according to the present embodiment will be described with reference to FIG.
As shown in FIG. 8, an oil supply path 26 that receives supply of lubricating oil from an oil pump 25 is provided with a hydraulic oil supply path 28 for supplying lubricating oil as hydraulic oil to the variable valve mechanism 5. And a lubricating oil passage 27 for supplying lubricating oil to a bearing portion of the camshaft 1 and lubricating portions such as the cams 2 and 4. Further, a bypass oil passage 43 is branched from the lubricating oil passage 27 on the way. The bypass oil passage 43 is connected to a rocker shaft oil passage 31 formed in the rocker shaft 6 via an orifice 44. Therefore, a small amount of hydraulic oil is always supplied to the rocker shaft oil passage 31 through the bypass oil passage 43.
[0066]
On the other hand, the hydraulic oil supply passage 28 is connected to a hydraulic switching valve (hereinafter, referred to as “OSV”) 40 for switching between supply of hydraulic oil to the variable valve mechanism 5 and discharge of hydraulic oil from the mechanism 5. . The OSV 40 is a three-port directional control valve, and is a hydraulic oil that connects the variable valve mechanism 5 to the OSV 40 via a rocker shaft oil passage 31 formed in the rocker shaft 6 in addition to the hydraulic fluid supply passage 28. The passage 45 and the drain passage 42 for recirculating the hydraulic oil in the variable valve mechanism 5 into the oil pan 24 are connected. This hydraulic oil passage 45 is actually formed in the cylinder head, and is connected to the rocker shaft oil passage 31 at the bearing of the rocker shaft 6.
[0067]
A check valve 41 is provided in the drain passage 42. The check valve 41 is opened only when the oil pressure on the upstream side of the check valve 41, that is, on the OSV 40 side in the drain passage 42 becomes equal to or higher than the set pressure. Therefore, the pressure of the hydraulic oil on the upstream side of the check valve 41 is always kept at the set pressure. The set pressure is set to a predetermined pressure equal to or lower than the switching oil pressure, that is, equal to or lower than an oil pressure for operating the lock mechanism of the variable valve mechanism 5.
[0068]
The OSV 40 is driven by an electromagnetic solenoid controlled by the ECU 39 and is a direction switching valve that communicates the working fluid passage 45 with one of the working oil supply passage 38 and the drain passage 42.
[0069]
When no voltage is applied to the electromagnetic solenoid, the hydraulic oil passage 45 and the drain passage 42 are connected. The hydraulic oil in the lock mechanism of the variable valve mechanism 5 is discharged through the rocker shaft oil passage 31, the hydraulic oil passage 45, and the drain passage. However, since the check valve 41 is provided in the drain passage 42, the set pressure is provided in the rocker shaft oil passage 31, the hydraulic oil passage 45, the upstream side of the drain passage 42, and in the variable valve mechanism 5. Hydraulic fluid is stored without being discharged. Actually, the hydraulic oil in the variable valve mechanism 5 leaks little by little through the clearance of the sliding portion, etc. However, since a small amount of hydraulic oil is always supplied through the bypass oil passage 43, the amount of leakage is The hydraulic oil in the variable valve mechanism 5 is compensated and maintained at the set pressure.
[0070]
At this time, even if the amount of hydraulic oil supplied from the bypass oil passage 43 increases due to the influence of hydraulic pressure or the like, and the hydraulic pressure in the variable valve mechanism 5 temporarily exceeds the set pressure, the check valve Immediately after the valve 41 is opened, the pressure is reduced to the set pressure. Therefore, the variable valve mechanism 5 does not malfunction due to the above-mentioned external oil pressure fluctuation.
[0071]
On the other hand, when a voltage is applied to the electromagnetic solenoid, the working fluid passage 39 and the working fluid supply passage 38 communicate with each other, so that the working oil is supplied to the variable valve mechanism 5. When the hydraulic oil is supplied, the hydraulic oil in the variable valve mechanism 5 rises above the switching hydraulic pressure, and the lock mechanism operates. Thus, the rocker arm 7 is swung by the high-speed cam 4.
[0072]
Here, in the present embodiment, when the OSV 40 is switched, the hydraulic oil of the set pressure is set in the hydraulic oil passage 45, the rocker shaft oil passage 31, and the variable valve mechanism 5 as described above. Is stored. Therefore, the time until the hydraulic oil in the oil passages 45, 31 and the variable valve mechanism 5 is increased to the switching hydraulic pressure is short, and the responsiveness of the cam switching operation is improved.
[0073]
In addition, since the working oil of an appropriate pressure is always stored in the variable valve mechanism 5, for example, the sliding portion between the rocker shaft 6 and the variable valve mechanism 5, the lock mechanism and the movable follower 12 Lubrication of a lubricating part such as a sliding part can be constantly maintained.
[0074]
By the way, if the check valve 41 is not provided in the drain passage 42 and the hydraulic oil is stored in the variable valve mechanism 5 using only the lubricating oil supplied from the bypass oil passage 43, the hydraulic oil falls due to gravity, As a result, the operating oil may not be stored in the variable valve mechanism 5. In order to solve such a situation, a structure in which the open end of the drain passage 42 is provided above the variable valve mechanism 5 or a structure in which the drain passage 42 is curved once above the variable valve mechanism 5 is adopted. Ingenuity such as is required. That is, the structure of the hydraulic circuit becomes complicated. In this regard, in the present embodiment, since the check valve 41 can suppress the drop of the hydraulic oil, the degree of freedom in the arrangement position of each oil passage or the OSV 40 can be increased.
[0075]
As described above, according to the present embodiment, the following effects can be obtained.
(1) Since hydraulic oil of a set pressure is stored in the variable valve mechanism 5 even when hydraulic oil is not supplied, the time required to obtain the required oil pressure at the time of cam switching can be shortened. Responsiveness can be improved.
[0076]
(2) By always supplying a small amount of hydraulic oil from the bypass oil passage 43, the hydraulic oil leaked from the variable valve mechanism 5 is compensated for, and the hydraulic pressure in the variable valve mechanism 5 when no hydraulic oil is supplied. Can be maintained at the set pressure.
[0077]
(3) Even when the hydraulic pressure in the variable valve mechanism 5 temporarily increases when the hydraulic oil is not supplied, the check valve 41 is opened and the hydraulic pressure in the mechanism 5 is reduced to the set pressure. Therefore, it is possible to prevent the occurrence of a malfunction of the variable valve mechanism 5 due to an external oil pressure fluctuation.
[0078]
(4) The hydraulic oil in the variable valve mechanism 5 is always maintained at an appropriate pressure, and each lubricating portion, for example, a sliding portion between the rocker shaft 6 and the variable valve mechanism 5, a lock mechanism and the movable follower 12 are controlled. The lubrication of the sliding parts can be constantly maintained.
[0079]
(5) By providing the check valve 41, the drop of the hydraulic oil due to gravity can be suppressed, so that the degree of freedom in the arrangement position of each oil passage or the OSV 40 or the like can be increased.
[0080]
The present embodiment may be modified as follows.
When the amount of the hydraulic oil leaking from the variable valve mechanism 5 is negligibly small, the bypass oil passage 43 that always supplies a small amount of the hydraulic oil may not be provided. Also in this case, the effects described in (1) and (3) to (5) can be obtained.
[0081]
In the present embodiment, the variable valve mechanism 5 that switches between two types of cams, 2 for low speed and 4 for high speed, has been described. However, the hydraulic circuit configuration may include, for example, the movable follower and the above-described movable follower. The present invention can be similarly applied to a variable valve mechanism having a plurality of lock mechanisms and switching three or more cams. However, in such a configuration, a hydraulic oil supply means capable of supplying hydraulic oil to each lock mechanism corresponding to each cam, and a hydraulic oil discharge means capable of individually discharging hydraulic oil to these lock mechanisms It is necessary to provide a separate hydraulic pressure holding means (check valve) for each hydraulic oil discharging means corresponding to each lock mechanism.
[0082]
As described above, the configuration, operation, and effect of each embodiment have been described. However, the embodiment of the present invention is not limited to each embodiment, and the configuration is changed as described below. You may.
[0083]
In the above-described embodiments, the variable valve operating device adopting the variable valve operating mechanism of switching the cam that opens and closes the engine valve by limiting and allowing the sliding of the movable follower in the rocker arm has been described. A plurality of rocker arms swinging respectively corresponding to a plurality of types of cams as shown in FIGS. 9 and 10, and connecting (locking) these rocker arms. A configuration may be adopted in which a variable valve mechanism that switches a cam that opens and closes an engine valve by separating (unlocking) is adopted.
[0086]
【The invention's effect】
According to the first aspect of the present invention, it is possible to reliably improve the responsiveness of the variable valve mechanism while appropriately preventing the occurrence of a malfunction of the variable valve mechanism due to the fluctuation of the hydraulic pressure. Become.
Further, according to the above configuration, the rotation of the support shaft is performed with respect to a variable valve mechanism that includes two hydraulic pressure control mechanisms and selects a cam that opens and closes the engine valve from among three types of cams. It is possible to adopt a mechanism for switching the supply of the working fluid by movement.
In addition, the supply of the hydraulic oil is temporarily interrupted during the switching from the medium speed cam to the high speed cam, and the situation where the engine valve is opened and closed by the low speed cam does not occur.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism provided in a variable valve apparatus of a first embodiment and a peripheral structure thereof.
FIG. 2 is a sectional view showing a lock mechanism of the variable valve mechanism.
FIG. 3 is a sectional view showing a lock mechanism of the variable valve mechanism.
FIG. 4 is a schematic diagram showing a hydraulic circuit configuration of the variable valve operating device of the embodiment.
FIG. 5 is an exemplary sectional view showing an operation example of the variable valve apparatus of the embodiment;
FIG. 6 is a cross-sectional view showing an operation example of the variable valve apparatus of the embodiment.
FIG. 7 is a sectional view showing an operation example of the variable valve apparatus of the embodiment.
FIG. 8 is a schematic diagram illustrating a hydraulic circuit configuration of a variable valve apparatus according to a second embodiment.
FIG. 9 is a cross-sectional view showing a structural example of a conventional variable valve mechanism.
FIG. 10 is a cross-sectional view showing a structural example of a conventional variable valve mechanism.
FIG. 11 is a schematic view showing an example of a hydraulic circuit configuration of a conventional variable valve device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Camshaft, 2 ... Low speed cam, 3 ... Medium speed cam, 4 ... High speed cam, 5 ... Variable valve mechanism, 6 ... Rocker arm, 9 ... Engine valve, 10 ... Roller follower, 12 ... Movable follower, 17: Hydraulic piston, 22: Hydraulic chamber, 23: Rocker arm oil path, 27: Lubricating oil path, 28: Cylinder oil path, 30: Oil supply port, 31: Rocker shaft oil path, 32: Medium speed side oil supply port, 33 ... Groove, 34 ... High-speed side oil supply port, 35 ... Electric motor, 36 ... Gear, 37 ... Gear, 39 ... Electronic control device (ECU), 40 ... Oil switching valve, 41 ... Check valve, 42 ... Drain passage, 43 ... Bypass oil passage, 44 throttle, 100 variable valve mechanism, 117 oil switching valve, 125 cylinder oil passage, 126 first lubricating oil passage, 127 throttle, 128, second lubricating oil passage, 129 ... bypass oil passage.

Claims (1)

It has two hydraulic pressure control mechanisms, each of which is hydraulically controlled, and a cam for opening and closing the engine valve from among three kinds of cams for low speed, medium speed, and high speed based on hydraulic pressure control of hydraulic fluid. In a variable valve mechanism including a variable valve mechanism that selectively switches, and a support shaft that rotatably supports the variable valve mechanism,
Hydraulic fluid for hydraulically controlling the variable valve mechanism is supplied through a hydraulic fluid passage formed in the support shaft,
The support shaft includes an opening for communicating or blocking the variable valve mechanism and the hydraulic fluid passage in the support shaft based on the rotation thereof ,
An opening communicating between the two hydraulic pressure control mechanisms and the hydraulic fluid passage in the support shaft communicates with each of the hydraulic pressure control mechanisms in a different support shaft rotation phase,
A groove extending in the circumferential direction of the support shaft from an opening for selecting a medium speed cam is formed on the circumferential surface of the support shaft, and the groove selects a high speed cam in the circumferential direction of the support shaft. A variable valve operating device extending to a position corresponding to the opening .

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