JPH11229836A - Variable valve gear - Google Patents

Abstract

(57) [Summary] 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. A variable valve mechanism (5) for selectively switching a cam for opening and closing an engine valve from a plurality of types of cams (2, 4) based on hydraulic control includes a hydraulic oil supply path (28), a drain path (42), and a hydraulic oil path. Hydraulic switching valve 4 to which 45 is connected
0 controls the hydraulic pressure. A check valve 41 is provided in a drain passage 42 that is a hydraulic oil discharge path from the variable valve mechanism 5, and keeps a hydraulic pressure in the mechanism 5 at a predetermined pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus for varying valve characteristics such as a valve lift and a working angle of an internal combustion engine, and more particularly to a variable valve apparatus having a plurality of cams having different cam characteristics. The present invention relates to a variable valve apparatus of a type in which valve characteristics are made variable by selectively switching a cam that drives the opening and closing of a valve.

[0002]

2. Description of the Related Art A variable valve actuation device that changes valve characteristics such as the opening and closing timing of an engine valve and the amount of lift thereof according to 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. 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 system is shown in Figs.
This will be described with reference to FIG. 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. The internal combustion engine provided with the variable valve operating system is a double overhead camshaft (DOHC) system having two intake and exhaust camshafts, and two intake valves and two exhaust valves are provided for each cylinder. It has a four-valve configuration.

A camshaft of an 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. The first and second rocker arms 10
A tappet screw 109 that is in contact with the upper end of the engine valve 9 is provided at the tip of each of the reference numerals 3 and 104.

[0005] Each of the rocker arms 103 to 105 has a receiving hole 106, 1 extending parallel to the rocker shaft 6.
07 and an accommodation hole 108 are formed. 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. Control pin 112
The mid rocker arm 105 by the coil spring 113
And the first and second switching pins 110, 1
11 is pressed.

A space 114 between one end of the first switching pin 110 and the closed end of the receiving 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 into the rocker shaft 6 in the axial direction. It communicates with the provided rocker shaft oil passage 31.

Here, hydraulic oil (usually,
Is not being supplied)
In the mode shown in FIG.
Numerals 5 are freely swingable. 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 so as to be idle. Therefore, each engine valve 9
Are the first and second rocker arms 103 and 104, respectively.
Through the low-speed cam.

On the other hand, the oil passages 23, 11
When oil is supplied via the first and second switching pins 110 and 111 and the regulating pin 1
12, moves to the second rocker arm 104 side against the urging force of the coil spring 113, as shown in FIG.
By this movement, the first and second switching pins 110, 111
Are inserted between the receiving hole 106 and the receiving hole 108 and between the receiving hole 107 and the receiving hole 108, and the rocker arms 103 to 105 are connected and swing 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.

Next, the configuration of a hydraulic circuit for supplying oil to the variable valve mechanism 100 in the variable valve apparatus will be described.
This 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 disposed to face these cams 101 and 102, respectively.

In the hydraulic circuit shown in FIG. 11, an oil pump 25 sucks oil in an oil pan 24 and pressurizes and discharges the oil to a hydraulic switching valve 117 via an oil supply passage 124. It is. This hydraulic switching valve 11
Numeral 7 comprises an electromagnetic three-port directional control valve. The first port 118 of the hydraulic switching valve 117 is an oil inlet,
It is connected to the oil supply path 124. Third port 12
Reference numeral 0 is connected to a first lubricating oil passage 126 that supplies lubricating oil to the low-speed cam 101. 2nd port 1
Reference numeral 19 is connected to an oil passage 125 for supplying 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. .

The hydraulic switching valve 117 has a guide hole 130.
Is formed, 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
Is communicated. 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 first port 118 and the second port 119 are formed by the small-diameter bypass passage 129 formed in the spool 121.
Also communicated with.

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 this 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 through the orifice 127 to lubricate the high-speed cam 102 and the bearing of the camshaft 1.

On the other hand, during low-speed operation, the solenoid 123
Is demagnetized, and oil flows through the first port 118 and the third port 120.
And, it is supplied to the low speed cam 101 via the first lubricating oil passage 126. At the same time, the first port 118 and the second port 119 are communicated with each other through the bypass passage 129, and a small amount of hydraulic oil is also 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 high-speed cam 1
02 and the bearing of the camshaft 1 are maintained in lubrication. 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 by the respective pins 110, 111, 112 against the urging force of the coil spring 113. Not as high as you move. Therefore, each rocker arm 103-10
5 swing independently, and the engine valve 9 is a low-speed cam 1
01 causes opening / closing drive (see FIG. 9).

As described above, in this hydraulic circuit configuration, even when the hydraulic pressure is not supplied to the variable valve mechanism 100, the bypass passage 1
By continuing to supply a small amount of oil via
The lubrication of the lubricating parts such as the bearings 01 and 102 and the bearing of the camshaft 1 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]

By the way, in order to improve the responsiveness at the time of cam switching, the hydraulic pressure in which the cam switching operation is performed, that is, the coil spring 1 is provided in the hydraulic chamber 114.
It is desirable to always apply as high a hydraulic pressure as possible below the hydraulic pressure at which the pins 110, 111, 112 move against the urging force of the thirteen. However, in the conventional variable valve apparatus that supplies the hydraulic oil to the variable valve mechanism through the hydraulic circuit having the above configuration, the amount of the hydraulic oil supplied through the bypass passage 129 is small, so that the hydraulic oil is supplied before the cam switching operation. 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.

On the other hand, in the case of the conventional variable valve apparatus,
By increasing the diameter of the bypass passage 129, the hydraulic pressure supplied into the hydraulic chamber 114 can be increased before the cam switching operation. However, when the diameter of the bypass passage 129 is simply enlarged, the cam switching is not always performed in a predetermined mode.

That is, the hydraulic oil supplied from the oil pump 25 is also supplied to the lubricating portion of the internal combustion engine and other hydraulic control mechanisms, etc., and the amount of oil consumed in these parts changes suddenly. The hydraulic pressure of the oil supplied to 117 may also fluctuate sharply. In this regard, 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 influence of the hydraulic pressure fluctuation is directly received, and the hydraulic pressure previously given in the hydraulic chamber 114 is increased. In this case, there is a concern that the pins 110, 111, and 112 may erroneously move due to the oil pressure fluctuation, and erroneous cam switching may be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent a malfunction from occurring and to improve the responsiveness of a variable valve mechanism without fail. It is to provide a device.

[0019]

In order to achieve the above object, according to the first aspect of the present invention, a cam for selectively opening and closing an engine valve is selected from a plurality of types of cams based on hydraulic pressure control of hydraulic fluid. In a variable valve operating device having a variable valve mechanism for switching to a variable valve mechanism and a support shaft rotatably supporting the variable valve mechanism, a hydraulic fluid for hydraulically controlling the variable valve mechanism is formed in the support shaft. The support shaft is provided with an opening for communicating or blocking the variable valve mechanism and the hydraulic fluid passage in the support shaft based on the rotation thereof. I do.

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 replenish 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 is rotated 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 the malfunction of the variable valve mechanism due to the hydraulic pressure fluctuation may occur. Is also suitably prevented.

According to a second aspect of the present invention, there is provided a variable valve mechanism for selectively switching a cam for opening and closing an engine valve from a plurality of types of cams based on hydraulic pressure control of a hydraulic fluid, and A hydraulic fluid supply device for supplying hydraulic fluid thereto, and a hydraulic fluid discharge device for discharging hydraulic fluid from the mechanism, wherein the hydraulic fluid discharge device includes a hydraulic fluid in the variable valve mechanism. The gist of the invention is to provide a hydraulic control means for maintaining the hydraulic pressure at a predetermined pressure.

With this configuration, when the hydraulic fluid is discharged from the variable valve mechanism, the hydraulic pressure in the variable valve mechanism is maintained at a predetermined pressure by the hydraulic pressure holding means. By storing the hydraulic fluid at a predetermined pressure in the variable valve mechanism even when the hydraulic fluid is discharged, the time required to raise the hydraulic fluid to the hydraulic pressure required at the time of the cam switching operation is also reduced. Become. Therefore, also in this case, the responsiveness of the variable valve mechanism can be improved. Further, by maintaining the hydraulic pressure in the variable valve mechanism at a predetermined pressure by the hydraulic pressure holding means, fluctuations in external hydraulic pressure are absorbed, and malfunction of the variable valve mechanism due to the fluctuation is prevented. You.

The invention described in claim 3 is the same as the invention described in claim 2.
In the variable valve mechanism according to the above, the hydraulic pressure holding means,
The gist of the present invention is that the check valve is configured to allow discharge of the hydraulic fluid when the hydraulic pressure of the hydraulic fluid in the variable valve mechanism becomes equal to or higher than a predetermined pressure.

According to this configuration, the hydraulic pressure holding means having the above function can be realized with an extremely simple configuration.
In particular, according to the above-mentioned check valve, it is easy to set the holding fluid pressure and to absorb fluctuations in the outside fluid pressure.

The invention described in claim 4 is the same as the claim 2
Or the variable valve operating device according to item 3, further comprising an auxiliary hydraulic pressure supply unit that auxiliary supplies a small amount of hydraulic fluid to the variable hydraulic valve mechanism even when the hydraulic fluid is discharged from the variable valve mechanism. .

According to this configuration, since the working fluid is supplied to the variable valve mechanism even when the working fluid is discharged, the fluid pressure can be smoothly maintained through the fluid pressure holding means.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below.
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.

First, the configuration of the variable valve mechanism provided in the variable valve apparatus according to the present embodiment will be described with reference to FIGS. FIG. 1 is a perspective view showing a part of the variable valve mechanism 5 and a part of the camshaft 1, and FIGS. 2 and 3 are sectional views of a hydraulic lock mechanism provided in the variable valve mechanism 5. I have.

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 with a cam profile in the order of the low speed cam 2, the medium speed cam 3, and the high speed cam 4 such that the opening / closing timing and the lift amount of the engine valve 9 driven by the cams are increased. ing.

Below the camshaft 1, the same shaft 1
The rocker shaft 6 is provided in parallel with the shaft. 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 that are provided symmetrically on the medium speed cam 3 side and the high speed cam 4 side and have basically the same function are denoted by the same reference numerals. In particular, the member on the side of the middle speed cam 3 has "a" at the end.
, And the members on the high-speed cam 4 side are distinguished by attaching "b" to the end thereof. Further in the following description,
Regarding the signs of these members, the identifiers “a”,
When “b” is omitted, both members on the medium speed cam 3 side and the high speed cam 4 side are shown unless otherwise specified.

The rocker arm 7 is rotatably supported at its base end by a 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.

At the center of the upper surface of the rocker arm 7, a roller follower 10 is rotatably supported. The roller follower 10 is rotatable with the low-speed cam 2. Further, a guide hole 1 having a circular cross section is provided on the upper surface of the rocker arm 7 and on both sides of the roller follower 10.
1a and 11b are formed vertically below. Movable followers 12a and 12b each having a substantially cylindrical shape are slidably inserted into the guide holes 11a and 11b. Among 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. These movable followers 12a and 12b are shown in FIG.
And as shown in FIG. 3, slippers 13a and 13b provided on the head and having a rectangular cross section and the guide holes 11a and 11b.
It is composed of a leg having a cylindrical shape so that it can be inserted into b. 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 slidably contacted with the middle 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.

On the other hand, as shown in FIGS. 1 to 3, below the rocker arm 7, cylinder holes 15a and 15b having a circular cross section orthogonal to the guide holes 11a and 11b are formed from the tip side of the rocker arm 7. I have. Side grooves 16a and 16b having a semicircular cross section are formed on both sides of the cylinder holes 15a and 15b.
5b is formed in parallel.

Next, a hydraulic lock mechanism (hereinafter simply referred to as a "lock mechanism") which is disposed in the cylinder holes 15a, 15b and the side grooves 16a, 16b to limit or allow the movable followers 12a, 12b to slide. ) Will be described in detail with reference to FIGS.

As shown in FIG. 2 and FIG.
A cylindrical hydraulic piston 17 is slidably inserted therein, and a semi-cylindrical side 18 is slidably inserted into the side groove 16. Note that the hydraulic piston 17 and the side 18 are assembled integrally, and are integrated with the position shown in FIG.
It is possible to slide between the positions shown in FIG.

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
2 is allowed to slide. Also, side 1
A flat surface is formed on the upper surface of the distal end portion of the movable follower 8 so that the bottom surface of the movable follower 12 can be contacted and supported when it is located 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 guide hole 11 is formed.
The sliding of the movable follower 12 in the inside is limited.

A groove having a rectangular cross section is formed on the base side of the rocker arm 7 in 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 on the tip side of the hydraulic piston 17. This coil spring 19
The spring receiving member 21 is urged toward the movable follower 12 and the hydraulic piston 17 is urged toward the inner bottom surface of the cylinder hole 15, that is, toward the base end of the rocker arm 7.

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.

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
At the same time, it moves from the position shown in FIG. 2 to the position shown in FIG. 3 against the urging force of the coil spring 19 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.

On the other hand, when the hydraulic pressure in the hydraulic chamber 22 drops to a certain level or less, the hydraulic piston 17 moves from the position shown in FIG. 3 to the position shown in FIG. Then, the restriction on the sliding of the movable follower 12 is released. The movable follower 12 slidable in this manner is separated from the rocker arm 7 and
In other words, it slides in the air.

In the present embodiment, the hydraulic piston 1 provided in the cylinder hole 15 or the side groove 16 is provided.
7, side 18, coil spring 19, spring receiving member 2
The lock mechanism that limits or cancels the sliding of the movable follower 12 in the guide hole 11 is configured by the hydraulic chamber 1 and the hydraulic chamber 22.

Next, the configuration of a hydraulic circuit for supplying hydraulic oil to the lock mechanism of the variable valve mechanism 5 will be described with reference to FIG.
It will be described based on. The oil pump 25 includes the oil pan 2
In addition to sucking the lubricating oil inside 4, the lubricating oil is actually pressurized and discharged 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.

The hydraulic oil supply passage 28 passes through a bearing 29 of the rocker shaft 6 and communicates with a sliding portion between the rocker shaft 6 and the coaxial receiver 29. The rocker shaft 6 is rotatably supported by the bearing 29. In the rocker shaft 6, each variable valve mechanism 5
A rocker shaft oil passage 31 for supplying hydraulic oil to the lock mechanism 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.

On the other hand, the hydraulic chamber 2 of the aforementioned variable valve mechanism 5
Rocker arm oil passages 23a, 2b communicating with 2a, 22b
The tip of 3b is extended to the sliding contact portion between the rocker arm 7 and the rocker shaft 6, and both rocker arm oil passages 23a,
23b are both opened in the same direction. A medium speed side opening 32 communicable with a medium speed side rocker arm oil passage 23a is provided in the rocker shaft 6 in a sliding contact portion with the rocker arm 7.
And a high-speed opening 34 that can communicate with the high-speed rocker arm oil passage 23b. These openings 32,
Through 34, the rocker shaft oil passage 31 and each rocker arm oil passage 23a and 23b can communicate with each other. Note that the middle speed side opening 32 and the high speed side opening 3
Reference numeral 4 denotes a medium-speed rocker arm oil passage 23a or a high-speed rocker arm oil passage 2 by rotating the rocker shaft 6.
3b or a structure in which the communication is interrupted. These medium speed side opening 32 and high speed side opening 34
The rocker shaft 6 is formed at a position sufficiently distant from the circumferential direction about the axis of the rocker shaft 6. Accordingly, with the rocker arm 7 swinging, the communication between the medium speed side rocker arm oil passage 23a and the medium speed side opening 32 and the connection between the high speed side rocker arm oil passage 23b and the high speed side opening 34 are not simultaneously performed. It has a structure (to be described later with reference to FIGS. 5 to 7). A groove 3 extending in the circumferential direction of the rocker shaft 6 from the medium speed side opening 32 is formed on the peripheral surface of the rocker shaft 6.
3 are formed. The groove 33 is provided in the rocker shaft 6.
In the circumferential direction of the above, it is extended to a position corresponding to the position where the high-speed side opening 34 is provided.

Next, a rocker shaft driving mechanism for rotating the rocker shaft 6 will be described with reference to FIG. A gear 37 is attached to the rocker shaft 6 so as to be able to rotate integrally. In the vicinity of the rocker shaft 6,
Electronic control unit (ECU) 39 for performing various controls of the internal combustion engine
(For example, a stepping motor) 35 that is driven and controlled by the controller 35 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, the motor 3
By controlling the rotation of the rocker shaft 5 by the ECU 39, the rotation phase of the rocker shaft 6 can be freely set.

Next, the operation of the above-described variable valve operating device will be described with reference to FIGS. 5 to 7.
FIG. 3 is a sectional view of the rocker shaft 6 and its vicinity at an axial position where the openings 32 and 34 are provided;
FIG. 5 shows a state at the time of low-speed operation of the engine, FIG. 6 shows a state at the time of medium-speed operation of the engine, and FIG.

When the engine is running at low speed, FIGS. 5 (a) and 5 (b)
As shown in FIG. 7, the rocker shaft 6 is rotated in a rotation phase in which neither of the openings 32, 34 communicates with the rocker arm oil passages 23a, 23b. Therefore, since the hydraulic oil is not supplied to the lock mechanisms on the medium speed side and the high speed side, both movable followers 12a and 12b can freely slide in the guide holes 11a and 11b. In this manner, both the medium-speed side and 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.

When the engine is operating at the medium speed, the rocker shaft 6 is rotated in a rotation phase in which the medium speed opening 32 and the medium speed rocker arm oil passage 23a communicate with each other, as shown in FIG. You. Thus, the hydraulic oil is supplied only to the lock mechanism on the middle speed side, and the sliding of the middle speed side movable follower 12a in the guide hole 11a is restricted. At this time, FIG.
As shown in (b), since the hydraulic oil is not supplied to the high-speed side lock mechanism, the high-speed side movable follower 12b slides as if it were. Therefore, the rocker arm 7 swings based on the rotation and pressing of the medium speed cam 3 having a higher lift.

At the time of high-speed operation of the engine, FIG.
As shown in FIG. 7, the rocker shaft 6 is rotated in a rotation phase in which the high-speed side opening 34 and the high-speed side 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 through the medium speed side opening 32 and the groove 33. Thus, on the medium speed side,
Hydraulic oil is supplied to both of the lock mechanisms on the high-speed side, and sliding of the movable followers 12a and 12b in the guide holes 11a and 11b is restricted. Therefore, rocker arm 6
Is swung based on rotation and pressing of the high-speed cam 4 having the highest lift.

The rotation phase of the rocker shaft 6 from the rotation phase at the time of medium speed operation of the engine shown in FIG. 6 to the rotation phase at the time of high speed operation of the engine shown in FIG. As a result, the hydraulic oil is continuously supplied to the lock mechanism on the medium speed side. Therefore, 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, so that the rocker arm 7 is not swung by the low speed cam 2. Has become. In particular, when the cam for swinging the rocker arm 7 is switched to the low-speed cam 2 at a time 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 driving resistance to the rotation of the camshaft 1 also fluctuates rapidly, the camshaft 1 and its driving 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.

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 if the supply of the hydraulic oil is started, the hydraulic valve of sufficient pressure is supplied to the variable valve mechanism until the hydraulic oil of sufficient pressure is filled in the oil passage reaching the variable valve mechanism. Can not do. Therefore, there has been 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 on which the variable valve mechanism 5 is mounted. Therefore, the rocker arm oil passage 23
Further, the cam switching operation can be performed only by filling the hydraulic chamber 22 with the hydraulic oil having a sufficient pressure, and the time until the cam switching operation is completed can be greatly reduced.

Further, in this embodiment, unless the rocker shaft 6 is rotated in the manner shown in FIG. 6 or FIG. 7, the supply of the hydraulic oil to the variable valve mechanism 5 is not performed. Variable valve mechanism 5 caused by oil pressure fluctuation
Does not malfunction.

Conventionally, in a variable valve operating device having two or more lock mechanisms and a variable valve mechanism for hydraulically controlling each of the lock mechanisms, a separate variable lock mechanism is provided for each lock mechanism. A hydraulic oil supply system was required.
Therefore, the rocker shaft oil passage 31 in the rocker shaft 6 has to 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. Has become.

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 present embodiment, the rocker shaft oil passage 31
Since the inside is always filled with the working oil, it is possible to always maintain the lubrication of such a sliding portion.

As described above, according to the present embodiment, the following effects can be obtained. (1) The rotation of the rocker shaft 6 causes the variable valve mechanism 5
Since the structure is such that the supply of the hydraulic oil to the hydraulic fluid is switched, the volume of the portion that needs to be filled with hydraulic oil with sufficient hydraulic pressure during the cam switching operation can be significantly reduced. Therefore, the cam switching time can be reduced, and the responsiveness of the variable valve mechanism 5 can be greatly improved.

(2) The rocker shaft 6 is connected to the filler holes 32, 3
The hydraulic oil is not supplied to the variable valve mechanism 5 unless the rotary valve 4 rotates in a manner that allows the rocker arm oil passages 23a and 23b to communicate with each other. Does not malfunction.

(3) By providing the groove 33, the medium-speed cam 3
When switching between the high-speed cam 4 and the low-speed cam 4, the supply of the hydraulic fluid to the lock mechanism is temporarily interrupted, and the occurrence of the rocker arm 7 being rocked by the low-speed cam 2 can be prevented.

(4) The hydraulic supply system up to the variable valve mechanism 5 can be unified, and the structure of the hydraulic circuit can be simplified. (5) Lubrication of the sliding portion between the rocker shaft 6 and the variable valve mechanism 5 can be constantly maintained.

The present embodiment may be modified as follows. In the present embodiment, the groove 33 is provided on the rocker shaft 6 side, but the groove 33 may be provided on the rocker arm 7 side.

In the above embodiment, the motor 35
For example, using a stepper motor, the rocker shaft 6
The rotation of the motor 35 is managed by providing a detector for detecting the rotation phase of the rocker shaft 6 and a limit switch corresponding to each rotation phase. The motor 35 may be changed to a servo motor.

The drive mechanism of the rocker shaft 6 is as follows:
The mechanism is not limited to the above-mentioned electric mechanism, and any mechanism such as a hydraulic type, a pneumatic type, and a mechanical type may be used as long as the actuator can rotate the rocker shaft 6.

Also, in the present embodiment, the variable valve mechanism 5 of the type in which three types of cams are switched between low speed 2, medium speed 3 and high speed 4 has been described. The supply switching mechanism further includes, for example, one movable follower and one lock mechanism, and a variable valve mechanism that switches between two types of cams, and three or more movable followers and a lock mechanism. The present invention can be similarly applied to a variable valve mechanism that switches between four or more cams.

(Second Embodiment) A second embodiment of the present invention will be described below. The variable valve operating device according to the present embodiment improves the responsiveness at the time of the cam switching operation by always increasing the oil pressure of the operating oil in the variable valve operating mechanism by providing a check valve in the discharge path of the operating oil. It is configured as a possible variable valve train.

In this embodiment, for convenience, a movable follower and a lock mechanism are provided as a variable valve mechanism, and two types of cams, ie, the low-speed cam 2 and the high-speed cam 4, are switched. The mechanism is assumed.

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 passage 26 that receives supply of lubricating oil from an oil pump 25 is provided with a hydraulic oil supply passage 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. 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.

On the other hand, the hydraulic oil supply passage 28 is provided with 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.
It is connected to. 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. Passage 45
And a drain passage 42 for recirculating the hydraulic oil in the variable valve mechanism 5 into the oil pan 24.
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.

A check valve 41 is provided in the drain passage 42. This check valve 41 is
The valve 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. This set pressure is set to a predetermined pressure equal to or lower than the switching oil pressure, that is, equal to or lower than the oil pressure for operating the lock mechanism of the variable valve mechanism 5.

The OSV 40 is a directional control valve driven by an electromagnetic solenoid controlled by the ECU 39 to connect the working fluid passage 45 to either the working oil supply passage 38 or the drain passage 42.

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 includes the rocker shaft oil passage 31, the hydraulic oil passage 45, and the drain passage 4
Exhausted through 2. However, this drain passage 42
Is provided with the check valve 41,
The hydraulic oil of the set pressure is stored in the upstream side of the rocker shaft oil passage 31, the hydraulic oil passage 45, and the drain passage 42 and in the variable valve mechanism 5 without being discharged. In practice,
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 leak is compensated and the variable valve is The hydraulic oil in the mechanism 5 is maintained at the set pressure.

At this time, even if the amount of hydraulic oil supplied from the bypass oil passage 43 increases due to the influence of oil pressure fluctuation and the like, and the oil pressure in the variable valve mechanism 5 temporarily exceeds the set pressure, Immediately after the check 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-described external oil pressure fluctuation.

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.
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.

Here, in the present embodiment, the OSV
At the time when the switch 40 is switched, the working oil of the set pressure is stored in the working oil passage 45, the rocker shaft oil passage 31, and the variable valve mechanism 5 as described above. Therefore, the time until the hydraulic oil in the oil passages 45, 31 and the variable valve mechanism 5 is boosted to the switching hydraulic pressure is short, and the responsiveness of the cam switching operation is improved.

Further, since the working oil at an appropriate pressure is always stored in the variable valve mechanism 5, for example, a sliding portion between the rocker shaft 6 and the variable valve mechanism 5, a locking mechanism, a movable The lubrication of the lubricating portion such as the sliding portion of the follower 12 can be constantly maintained.

When the check valve 41 is not provided in the drain passage 42 and the hydraulic oil is stored in the variable valve mechanism 5 only by the lubricating oil supplied from the bypass oil passage 43, the hydraulic oil falls due to gravity. As a result, the working oil may not be stored in the variable valve mechanism 5. In order to solve such a situation, the open end of the drain passage 42 is provided above the variable valve mechanism 5 or the drain passage 42 is
It is necessary to devise such a structure as to bend upward.
That is, the structure of the hydraulic circuit becomes complicated. In this regard, in this embodiment, since the check valve 41 can suppress the drop of the hydraulic oil, each oil passage or the OSV
The degree of freedom of the arrangement position such as 40 can be increased.

As described above, according to the present embodiment, the following effects can be obtained. (1) Since hydraulic oil having 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 is reduced, and the variable valve mechanism 5 Responsiveness can be improved.

(2) By always supplying a small amount of hydraulic oil from the bypass oil passage 43, hydraulic oil leaked from the variable valve mechanism 5 is supplemented, and the variable valve mechanism 5 when no hydraulic oil is supplied is supplied. Can be maintained at the set pressure.

(3) Even if the oil pressure in the variable valve mechanism 5 temporarily increases when the hydraulic oil is not supplied, the check valve 41 is opened and the oil pressure in the mechanism 5 is reduced to the set pressure. You. Therefore, it is possible to prevent the occurrence of a malfunction of the variable valve mechanism 5 due to an external oil pressure fluctuation.

(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 a movable member Lubrication of the sliding portion and the like of the follower 12 can be constantly maintained.

(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 can be increased.

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.

Also, in this embodiment, the variable valve mechanism 5 of the type in which two kinds of cams, 2 for low speed and 4 for high speed, are switched.
However, the above-described hydraulic circuit configuration is similarly applied to, for example, a variable valve mechanism that includes a plurality of the movable followers and the lock mechanism and switches three or more types of cams. be able to. However, in such a configuration, a hydraulic oil supply means capable of individually supplying hydraulic oil to a 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.

The configuration, operation, and effects of each embodiment have been described above. However, the embodiments of the present invention are not limited to these embodiments, and the configurations are modified as follows. May be implemented.

In each of the above embodiments, the variable valve mechanism adopting the variable valve mechanism of the type in which the cam for opening and closing the engine valve is switched by limiting and allowing the sliding of the movable follower in the rocker arm. I explained,
A variable valve mechanism of another cam switching type, for example, a plurality of types of cams as shown in FIGS. 9 and 10 is provided with a plurality of rocker arms which respectively swing, and these rocker arms are connected (locked) and separated. A configuration may be adopted in which a variable valve mechanism that switches the cam that opens and closes the engine valve by releasing (unlocking) is adopted.

Next, technical ideas other than those described in the claims, which can be understood from the above embodiments, will be described below together with their effects. (1) The variable valve operating device according to claim 1, wherein the variable valve operating mechanism includes two hydraulic pressure control mechanisms, each of which is hydraulically controlled separately, and controls the engine valve from three types of cams. A cam for opening / closing drive is selected, and an opening communicating between the two hydraulic pressure control mechanisms and the hydraulic fluid passage in the support shaft is provided with a separate support shaft rotation for each hydraulic pressure control mechanism. A variable valve operating device that communicates in a dynamic phase.

According to the configuration described in (1), the variable valve mechanism of the type that includes two hydraulic pressure control mechanisms and selects a cam for opening and closing the engine valve from among three kinds of cams. On the other hand, a mechanism for switching the supply of the hydraulic fluid by rotating the support shaft can be adopted, and the same effect as that of the first aspect can be obtained.

[0086]

According to the first aspect of the present invention, the responsiveness of the variable valve mechanism is reliably improved while appropriately preventing the occurrence of a malfunction of the variable valve mechanism due to the fluctuation of the hydraulic pressure. Will be able to do it.

According to the second aspect of the present invention, the responsiveness of the variable valve mechanism is reliably improved while appropriately preventing the occurrence of a malfunction of the variable valve mechanism due to the fluctuation of the hydraulic pressure. Will be able to do it.

According to the third aspect of the present invention, the hydraulic pressure holding means can be realized with an extremely simple configuration. According to the fourth aspect of the present invention, the fluid pressure can be smoothly maintained through the fluid pressure maintaining means.

[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 sectional view showing an operation example of the variable valve apparatus of the embodiment.

FIG. 7 is a cross-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 operating device 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 diagram showing an example of a hydraulic circuit configuration of a conventional variable valve device.

[Explanation 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 passage, 27 ... lubrication oil passage, 28 ... cylinder oil passage, 30 ... oil filler port, 31 ... rocker shaft oil passage, 3
2 ... Middle-speed oil filler, 33 ... Groove, 34 ... High-speed oil filler, 3
5: electric motor, 36: gear, 37: gear, 39: electronic control unit (ECU), 40: oil switching valve, 41: check valve, 42: drain passage, 43: bypass oil passage, 4
4 throttle, 100 variable valve mechanism 117 oil switching valve
125 ... Cylinder oil passage, 126 ... First lubrication oil passage, 12
7 ... throttle, 128 ... second lubricating oil passage, 129 ... bypass oil passage.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Yoshihara 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Hiromasa Suzuki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (4)

[Claims] 1. A variable valve mechanism for selectively switching a cam for opening and closing an engine valve from a plurality of types of cams based on hydraulic pressure control of a hydraulic fluid, and rotatably supporting the variable valve mechanism. In a variable valve device including a support shaft, a hydraulic fluid for hydraulically controlling the variable valve mechanism is supplied through a hydraulic fluid passage formed in the support shaft, and the support shaft is rotated by its rotation. A variable valve operating device provided with an opening for communicating or blocking the variable valve operating mechanism and a hydraulic fluid passage in the support shaft. 2. A variable valve mechanism for selectively switching a cam for opening and closing an engine valve from a plurality of cams based on hydraulic pressure control of the hydraulic fluid, and a hydraulic fluid for supplying the hydraulic fluid to the mechanism. In a variable valve apparatus including a supply unit and a hydraulic fluid discharge unit that discharges hydraulic fluid from the mechanism, the hydraulic fluid discharge unit maintains a hydraulic pressure of the hydraulic fluid in the variable valve mechanism at a predetermined pressure. A variable valve actuating device comprising a hydraulic control means. 3. The control valve according to claim 2, wherein the hydraulic pressure holding means is a check valve that permits discharge of the hydraulic fluid when the hydraulic pressure of the hydraulic fluid in the variable valve mechanism becomes equal to or higher than a predetermined pressure. Variable valve mechanism. 4. The variable valve operating apparatus according to claim 2, further comprising: an auxiliary hydraulic pressure supply unit that auxiliary supplies a small amount of hydraulic fluid to the variable valve mechanism even when the hydraulic fluid is discharged from the variable valve mechanism. A variable valve apparatus further comprising: