JP2003129811A - Variable valve unit of internal-combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve unit which is high in responsivity without causing an unstable operation of a control shaft in case of low hydraulic pressure. SOLUTION: A variable lift actuator 100 which adjusts an axial position of a control shaft 132 is provided with an assisting spring 111 which applies an assisting force. The assisting force of the assisting spring 111 is set higher than the thrust force of the control shaft 132 at a low lift side of the control shaft 132. The variable lift actuator 100 is provided with a locking pin 113 which protrudes into a second hydraulic chamber 107 by an applied force from the locking spring 116 in case of low hydraulic pressure, and protrudes in engagement with a piston 104 and regulates movements of the piston 104.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve operating system for an internal combustion engine, and more particularly, to continuously changing the valve lift amount by interlocking with the axial position of the control shaft by moving the control shaft in the axial direction. And a variable valve operating device.

[0002]

2. Description of the Related Art In order to continuously adjust the valve lift amount of an intake valve of an internal combustion engine according to the operating state of the internal combustion engine, a cam provided with a three-dimensional cam whose cam nose height gradually increases in the axial direction. A variable valve operating device is known in which a shaft is moved in the axial direction (Japanese Patent Laid-Open No. 2000-54).
814 publication).

[0003]

In the variable valve operating device in which the valve lift amount is continuously variable by moving the cam shaft in the axial direction as described above, the cam surface of the three-dimensional cam is inclined in the axial direction. Therefore, thrust force is generated in the direction to reduce the valve lift amount. Moreover, as the valve lift amount increases, the compression amount of the valve spring increases and the restoring force of the valve spring gradually increases, so that the thrust force also increases.

An actuator for moving the camshaft in the axial direction when the variable valve device is used to adjust the intake air amount of the internal combustion engine by the valve lift amount of the intake valve instead of the throttle valve. High responsiveness is required. Particularly when a hydraulic actuator is used, it is required to reduce the flow rate of hydraulic oil by reducing the piston diameter in order to achieve high response. However, if the piston diameter is reduced, the output of the actuator cannot cope with the increase in the thrust force described above, and the minimum operating hydraulic pressure in the case where the valve lift amount is large may deteriorate, or the responsiveness may deteriorate.

In order to solve these problems, it is conceivable to provide an assist spring to generate an assist force that opposes the thrust force. However, as described above, the thrust force increases as the valve lift amount increases, but the biasing force of the assist spring decreases as the camshaft moves toward the higher lift side. Therefore, it is necessary to increase the biasing force of the assist spring. .

However, when the biasing force of the assist spring is increased in this way, the hydraulic pressure of the hydraulic actuator is insufficient before the rise of the operating hydraulic pressure at the time of starting the internal combustion engine and during the decrease of the hydraulic pressure at the time of stopping the internal combustion engine, and May fall below bias. In this case, the urging force of the assist spring causes the piston to move toward the high lift side, making it impossible to hold the piston at the low lift side, which causes a problem that the valve lift amount deviates from a predetermined value.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable valve operating device for an internal combustion engine having high responsiveness without causing unstable operation of the control shaft at low hydraulic pressure. To provide.

[0008]

[Means for Solving the Problems] Means and effects for achieving the above object will be described below. Claim 1
The invention described in (1) is a variable valve actuation device for an internal combustion engine, wherein the valve lift amount is continuously variable by interlocking with the axial position of the control shaft by moving the control shaft in the axial direction. A piston provided in a part of the shaft and moving integrally with the control shaft by hydraulic pressure supplied to the cylinder, and a movement of the control shaft to a high lift side against the thrust force generated in the control shaft. A hydraulic actuator having an assisting force giving means for giving an assisting force for assisting, and setting the assisting force of the assisting force giving means larger than the thrust force of the control shaft on the low lift side of the control shaft. , With the assist force at low hydraulic pressure Characterized in that a locking means for restricting the movement of the high-lift side of the control shaft by the assist force means.

With the above arrangement, the hydraulic pressure of the hydraulic actuator may become insufficient and fall below the urging force of the assisting force imparting means before the operating hydraulic pressure rises when the internal combustion engine is started and during the hydraulic pressure drop when the internal combustion engine is stopped. is there. However, in this case, since the movement of the control shaft to the high lift side is restricted by the locking means, it is possible to hold the control shaft on the low lift side and suppress the unstable operation, thereby reducing the valve lift amount. It can be held at a predetermined value. Further, during normal operation of the internal combustion engine, the assist force imparting means imparts an assist force for assisting the movement of the control shaft to the high lift side, so that the minimum operating oil pressure of the hydraulic actuator can be made a small value. The responsiveness of the control shaft can be improved.

According to a second aspect of the present invention, in the first aspect, the lock means is a lock pin projecting in a direction substantially orthogonal to an axial direction of the control shaft in the cylinder by an urging force of a lock spring. The lock pin engages with the piston to restrict movement of the piston.

According to the above arrangement, when the hydraulic pressure of the hydraulic actuator is insufficient, the lock pin projects by the biasing force of the lock spring and engages with the piston, and the movement of the piston is restricted. Therefore, the movement of the control shaft to the high lift side is restricted, the control shaft is held on the low lift side, and unstable operation is suppressed.

According to a third aspect of the present invention, in the second aspect, the lock means prevents the lock pin from resisting the biasing force of the lock spring when the control shaft is moved to the high lift side. It is characterized in that it is provided with a hydraulic chamber that applies hydraulic pressure so as to escape from the cylinder.

According to the above construction, during normal operation of the internal combustion engine, the working oil pressure rises to secure the required working oil pressure, so that when the control shaft is moved to the high lift side, the oil pressure remains in the hydraulic chamber. The lock pin can be released from the cylinder against the urging force of the lock spring and the piston can be unlocked.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a camshaft rotatably driven by a crankshaft of an internal combustion engine, a cam provided on the camshaft, and the camshaft. Are swingably supported by different shafts, and have an input part and an output part, so that when the input part is driven by the cam, an intermediary drive mechanism that drives a valve at the output part, and movement in the axial direction And the relative position between the input shaft and the output shaft of the intermediary drive mechanism by moving the control shaft in the axial direction. By providing the hydraulic actuator that adjusts the phase difference, it is possible to continuously change the valve lift amount in conjunction with the axial position of the control shaft. And butterflies.

The variable valve operating device may include a cam shaft, a cam, an intermediary drive mechanism, a control shaft, and a hydraulic actuator. Even in such a structure, the structure of the locking means described above can restrict the movement of the control shaft to the high lift side and hold the control shaft on the low lift side, thereby suppressing the unstable operation of the control shaft. be able to.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the three-dimensional cam whose cam profile changes in the axial direction is moved in the axial direction so that the valve lift amount is continuous. It is a variable valve mechanism that is variable, and the amount of movement of the control shaft in the axial direction is interlocked with the amount of movement of the three-dimensional cam in the axial direction.

The variable valve operating device may include the three-dimensional cam and the control shaft. Even in such a structure, the structure of the locking means described above can restrict the movement of the control shaft to the high lift side and hold the control shaft on the low lift side, thereby suppressing the unstable operation of the control shaft. be able to.

According to a sixth aspect of the present invention, in the fifth aspect, the control shaft doubles as a cam shaft of the three-dimensional cam. As described above, the control shaft may also serve as the cam shaft of the three-dimensional cam, and by the configuration of the locking means described above, movement of the control shaft to the high lift side can be restricted to hold the control shaft on the low lift side. Therefore, the unstable operation of the control shaft can be suppressed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a gasoline engine (hereinafter abbreviated as "engine") as an internal combustion engine equipped with a variable valve operating device to which the above-described invention is applied.
FIG. 3 is a block diagram showing a schematic configuration of a control system and its control system.

The engine 2 is mounted on an automobile for driving the automobile. This engine 2
A cylinder block 4, a piston (not shown), a cylinder head 8 mounted on the cylinder block 4, and the like are provided. A plurality of cylinders, for example, four cylinders 2a in this case, are formed in the cylinder block 4, and a combustion chamber 10 defined by the cylinder block 4, the piston and the cylinder head 8 is formed in each cylinder 2a.

Each combustion chamber 10 has a first intake valve 12a, a second intake valve 12b, and a first exhaust valve 16 respectively.
a and the second exhaust valve 16b are arranged. The first intake valve 12a has a first intake port 14a, the second intake valve 12b has a second intake port 14b, the first exhaust valve 16a has a first exhaust port 18a, and the second exhaust valve 16a.
b opens and closes the second exhaust port 18b.

The first intake port 14a and the second intake port 14b of each cylinder 2a are connected to a surge tank 32 via an intake passage 30a formed in the intake manifold 30. Fuel injectors 34 are arranged in the respective intake passages 30a so that fuel can be injected into the first intake port 14a and the second intake port 14b.

The surge tank 32 is connected to an air cleaner 42 via an intake duct 40. No throttle valve is arranged in the intake duct 40.
The intake air amount control according to the operation of the accelerator pedal 74 and the engine speed NE during idle speed control is performed by adjusting the valve lift amounts of the first intake valve 12a and the second intake valve 12b.

Both intake valves 12a and 12b are driven by a lift of an intake cam 45a provided on an intake cam shaft 45 via an intermediary drive mechanism 120, which will be described later, arranged on the cylinder head 8 as shown in FIG. This is done by transmitting motion. In this transmission, the valve lift amount is adjusted by adjusting the lift transmission state by the intermediary drive mechanism 120 by the action of the lift amount variable actuator 100 described later. The intake camshaft 45 is interlocked with the rotation of a crankshaft 49 of the engine 2 via a timing sprocket (a timing gear or a timing pulley) provided at one end and a timing chain 47.

The first exhaust valve 16a which opens and closes the first exhaust port 18a and the second exhaust valve 1 which opens and closes the second exhaust port 18b of each cylinder 2a shown in FIG.
6b is an exhaust camshaft 46 accompanying the rotation of the engine 2.
The exhaust cam 46a (FIG. 2) provided in (FIG. 2) is opened and closed with a constant valve lift amount. The first exhaust port 18a and the second exhaust port 18b of each cylinder 2a are connected to the exhaust manifold 48. As a result, the exhaust gas is discharged to the outside via the catalytic converter 50.

An electronic control unit (hereinafter referred to as an ECU) 60 is composed of a digital computer, and has a CPU, a RAM, and a RO that are mutually connected via a bidirectional bus.
M, various driver circuits, an input port, an output port, and the like.

The amount of depression of the accelerator pedal 74 output by the accelerator opening sensor 76 to the input port of the ECU 60 (hereinafter referred to as "accelerator opening ACCP").
An output voltage proportional to, a pulse output every time the crankshaft rotates 30 ° by the crank angle sensor 82,
Intake duct 40 output by intake air amount sensor 84
The output voltage corresponding to the intake air amount GA flowing through the engine 2, the output voltage corresponding to the cooling water temperature THW of the engine 2 output by the water temperature sensor 86 provided in the cylinder block 4 of the engine 2, and the exhaust voltage provided in the exhaust manifold 48. According to the output voltage corresponding to the air-fuel ratio output by the fuel ratio sensor 88, the axial displacement output by the shaft position sensor 90 that detects the axial displacement of the control shaft 132, which will be described later, moved by the lift amount variable actuator 100. The output voltage and the output pulse from the cam angle sensor 92 that detects the cam angle of the intake cam 45a that drives the intake valves 12a and 12b via the intermediary drive mechanism 120 are input. The ECU 60 calculates the current crank angle based on the output pulse of the crank angle sensor 82 and the pulse of the cam angle sensor 92, and calculates the engine speed NE from the frequency of the output pulse of the crank angle sensor 82.

Besides, various signals are input to the input port of the ECU 60, but they are not shown in the present embodiment because they are not important for explanation in this embodiment. The output port of the ECU 60 is connected to each fuel injector 34 via a corresponding drive circuit. The ECU 60 controls each fuel injector 34 according to the operating state of the engine 2.
Valve opening control, and fuel injection timing control and fuel injection amount control are executed.

The output port of the ECU 60 is connected to an oil control valve (hereinafter referred to as "OCV") 94 via a drive circuit, and the ECU 60 controls the OCV 94 according to the operating state of the engine 2 such as the required intake air amount. The variable lift actuator 100 is controlled by the hydraulic control by

Here, the lift amount variable actuator 10
The internal structure of 0 is shown in FIGS. The variable lift actuator 100 has a cylinder 103 inside a housing 101, which is coaxial with an auxiliary shaft 102 as a control shaft. This cylinder 103
Has a slightly smaller diameter on the auxiliary shaft 102 side. A substantially cylindrical piston 104 is arranged in the cylinder 103 so as to be movable in the axial direction of the cylinder 103. The auxiliary shaft 102 is fixed to the piston 104 by a fixing bolt 105 penetrating from the right side of FIG. 3 via a bolt insertion hole 104a penetrating the piston 104 in the axial direction, and moves in the axial direction together with the piston 104. It is like this. The auxiliary shaft 102 is mounted on the control shaft 1 through the rolling bearing 108.
Connected to 32. The control shaft 13
On the side opposite to 2, the stroke sensor core 109 is provided on the auxiliary shaft 102, and the tip of this stroke sensor core 109 is inserted into the stroke sensor coil 110 attached to the housing 101.
As a result, the shaft position of the control shaft 132 is detected, and a signal corresponding to the shaft position is output from the stroke sensor coil 110 to the ECU 60.

The cylinder 103 is divided into a first hydraulic chamber 106 and a second hydraulic chamber 107 by the piston 104. Then, through the OCV 94 described above, the ECU
When 60 adjusts the supply and discharge of the hydraulic pressure to the first hydraulic chamber 106 and the second hydraulic chamber 107, the entire piston 104 moves in the axial direction and the axial position of the control shaft 132 is adjusted.

OCV94 is an electromagnetic solenoid type 4 port 3
This is a position switching valve, and as shown in FIG. 3, in the demagnetized state of the electromagnetic solenoid (hereinafter, referred to as “low lift drive state”), the working oil in the first hydraulic chamber is transferred to the oil pan 97 via the discharge passage 96. Will be returned. Supply passage 95 into the second hydraulic chamber
High-pressure hydraulic oil is supplied from the oil pump P via the. As a result, the control shaft 132 can be moved in the L direction in FIG. 3 and the valve working angle and the valve lift amount of the intake valves 12a and 12b can be reduced by the function of the intermediary drive mechanism 120.

When the electromagnetic solenoid is 100% excited (hereinafter referred to as "high lift drive state"),
An oil pump P is introduced into the first hydraulic chamber via a supply passage 95.
Supplies high-pressure hydraulic oil. The hydraulic oil in the second hydraulic chamber is returned to the oil pan 97 via the discharge passage 96. This causes the control shaft 132
And the valve lift amount of the intake valves 12a and 12b can be increased by the function of the intermediary drive mechanism 120.

Further, when the power supply to the electromagnetic solenoid is controlled to a medium state (hereinafter referred to as "neutral state"), the first and second hydraulic chambers are not connected to the supply passage 95 or the discharge passage 96. It will be closed. As a result, the axial movement of the control shaft 132 is stopped and the valve lift of the intake valves 12a and 12b can be maintained.

The piston 104 has a first hydraulic chamber 106.
A flange portion 104b is formed so as to extend to the side, and an assist force imparting means 111 is provided in the first hydraulic chamber 106 between the piston 104 and the inner wall. The assisting force imparting means 111 generates an assisting force based on the restoring force of the elastic body, and in this embodiment, an assist spring is used as the elastic body. The assist spring 111 opposes the thrust force generated in the control shaft 132 to oppose the control shaft 1
An assisting force is provided to assist the movement of 32 to the high lift side. Assist spring 11
The assist force of 1 is set to a value larger than the thrust force generated in the control shaft 132 on the low lift side of the control shaft 132.

The piston 104 is provided in the housing 101.
Guide bush 112 extending in a direction orthogonal to the axial direction of the
And a lock pin 113 is slidably arranged in the guide bush 112. Also, the step 112a formed on the guide bush 112 and the lock pin 11
A third hydraulic chamber 114 is formed in the guide bush 112 by the step portion 113a formed in the guide bush 112. Third
The hydraulic pressure is supplied to the first hydraulic chamber 106 at the same time as the hydraulic pressure is supplied to the first hydraulic chamber 114.

The stopper 11 screwed into the housing 101
A lock spring 116 made of a compression spring is interposed between the lock pin 5 and the lock pin 113. The lock spring 116 constantly urges the lock pin 113 toward the second hydraulic chamber 107 side. Therefore, when the engine 2 starts up and before the hydraulic pressure rises,
When the hydraulic pressure in the second hydraulic chamber 107 and the third hydraulic chamber 114 is insufficient and falls below the urging force of the lock spring 116 during the hydraulic pressure reduction at the time of stop, the lock pin 113 moves the second hydraulic pressure as shown in FIG. It projects into the chamber 107. As a result, the lock pin 113 engages with the piston 104 to lock and hold the piston 104 on the low lift side.

Further, during normal operation of the engine 2,
The working hydraulic pressure supplied from the OCV 94 rises to secure the required working hydraulic pressure. Therefore, when the control shaft 132 moves to the high lift side, the hydraulic pressure is supplied to the third hydraulic chamber 114 to exceed the biasing force of the lock spring 116, and the lock pin 113 comes out of the second hydraulic chamber 107 to move the piston 104. The lock is released. In the normal operating state after the engine 2 is started, when the control shaft 132 is moved to the low lift side, the hydraulic pressure is supplied to the second hydraulic chamber 107 to cause the lock spring 11 to move.
6 is exceeded and the lock pin 113 moves to the second hydraulic chamber 1
The piston 104 is released from the inside of 07 and the lock of the piston 104 is released.

FIG. 5 shows the relationship between the thrust force and the assist force of the assist spring 111 that accompany the amount of movement of the control shaft 132 in the H direction that is actually designed based on the above-mentioned relationship. That is, when the amount of movement of the control shaft 132 in the H direction is “0 (mm)” (the limit position in the L direction), the assist force Fa has the maximum value Fa1. As the control shaft 132 moves in the H direction, the assist force Fa decreases as the assist spring 111 extends, and the assist force Fa reaches the minimum value F at the limit position in the H direction.
It becomes a2. The thrust force Fs (however, the acting direction of the force is opposite to the assist force) generated by the operation of the intermediary drive mechanism 120 described later is such that the movement amount of the control shaft 132 in the H direction is “0 (mm)” (in the L direction. The minimum value Fs1 becomes the minimum value Fs1. Control shaft 1
The thrust force Fs increases as 32 moves in the H direction,
At the limit position in the H direction, the thrust force Fs has the maximum value Fs2. The rising pattern of the thrust force Fs generated by the intermediary drive mechanism 120 slightly changes depending on the rotation speed of the engine 2.

Next, the intermediary drive mechanism 120 will be described with reference to FIGS. The intermediary drive mechanism 120 includes an input section 122 provided in the center of the figure, a first swing cam 124 (corresponding to an “output section”) provided on the left side of the figure, and a second swing cam 126 provided on the right side of the figure. (Corresponding to “output unit”). Housing 122a of these input parts 122
And each housing 124a of the swing cams 124, 126,
Each of the 126a has a cylindrical shape with the same outer diameter.

FIG. 7 shows each housing 122a, 124a,
It is the perspective view which horizontally fractured | ruptured 126a. Here, the housing 122a of the input part 122 has a space inside in the axial direction, and the helical spline 122b (corresponding to the "input part spline") is formed in a spiral shape of a right-hand screw in the axial direction on the inner peripheral surface of this space. Are formed. Two arms 122c and 122d are formed so as to project in parallel from the outer peripheral surface. A shaft 122e is stretched between the tips of the arms 122c and 122d. The shaft 122e is parallel to the axial direction of the housing 122a, and the roller 122f is rotatably attached.

Housing 124a of the first swing cam 124
Is internally provided with a space in the axial direction, and a helical spline 124b (corresponding to an "output portion spline") formed in a spiral shape of a left screw in the axial direction is formed on the inner peripheral surface of the internal space. The left end of this internal space is covered with a ring-shaped bearing portion 124c having a central hole with a small diameter. A substantially triangular nose 124d is formed so as to project from the outer peripheral surface. One side of the nose 124d is a cam surface 124e that is curved in a concave shape.

Housing 126a of the second swing cam 126
Is internally provided with a space in the axial direction, and a helical spline 126b (corresponding to an "output portion spline") formed in a spiral shape of a left screw in the axial direction is formed on the inner peripheral surface of the internal space. The right end of this internal space is covered with a ring-shaped bearing portion 126c having a center hole with a small diameter. Further, a substantially triangular nose 126d is formed so as to project from the outer peripheral surface. One side of the nose 126d is a cam surface 126e that is curved in a concave shape.

The first swing cam 124 and the second swing cam 12
6 is the input unit 1 with the bearings 124c and 126c outside.
The two end faces of 22 are coaxially contacted with each other, and the whole has a substantially columnar shape having an internal space as shown in FIG.

Input unit 122 and two swing cams 124, 1
A slider gear 128 is provided in the internal space constituted by 26.
Are arranged. The slider gear 128 has a substantially columnar shape, and an input helical spline 128a formed in a spiral shape with a right screw is formed in the center of the outer peripheral surface. At the left end of the input helical spline 128a, a first output helical spline 128c formed in a spiral shape of a left screw is formed with a small diameter portion 128b sandwiched therebetween. or,
At the right end of the input helical spline 128a, a second output helical spline 128e formed in a spiral shape of a left screw is formed with the small diameter portion 128d interposed therebetween.
Incidentally, these output helical splines 128c, 128
The outer diameter of e is smaller than the outer diameter of the input helical spline 128a.

A through hole 128f is formed in the slider gear 128 in the central axis direction. A long hole 128g for opening the through hole 128f to the outer peripheral surface is formed in the one small diameter portion 128d. This long hole 128g
Are formed to be long in the circumferential direction.

Through hole 128f of this slider gear 128
A support pipe 130 shown in FIG. 8 is arranged therein so as to be slidable in the circumferential direction. 8A is a plan view and FIG.
8B is a front view and FIG. 8C is a right side view. As shown in FIG. 2, one support pipe 130 is provided commonly to all the intermediary drive mechanisms 120 (here, four). It should be noted that each of the intermediary drive mechanisms 12 is attached to the support pipe 130.
An elongated hole 130a that is elongated in the axial direction is opened for each 0.

Further, a control shaft 132 penetrates through the support pipe 130 so as to be slidable in the axial direction. This control shaft 132 is also common to all the intermediary drive mechanisms 120 like the support pipe 130.
Books are provided. The control shaft 132
A locking pin 132a is projected for each intermediary drive mechanism 120. The locking pin 132a penetrates the elongated hole 130a formed in the support pipe 130. Further, the locking pin 132a of the control shaft 132 is provided with a circumferential elongated hole 128 formed in the slider gear 128.
The tip is also inserted in g.

Due to the axially elongated hole 130a formed in the support pipe 130, the support pin 130 of the locking pin 132a of the control shaft 132 is fixed to the cylinder head 8.
Even when fixed, the slider gear 128 can be moved in the axial direction by moving in the axial direction.
Further, the slider gear 128 itself has a long hole 128 in the circumferential direction.
By being locked to the locking pin 132a at g, the axial position is determined by the locking pin 132a, but it is swingable about the axis.

In the slider gear 128, the input helical spline 128a is meshed with the helical spline 122b inside the input section 122. or,
The first output helical spline 128c is meshed with the helical spline 124b inside the first swing cam 124, and the second output helical spline 128e is meshed with the helical spline 126b inside the second swing cam 126.

Each intermediary drive mechanism 12 configured in this way
0 is the bearing portions 124c, 12 of the swing cams 124, 126.
As shown in FIG. 2, on the side of 6c, it is sandwiched by the standing wall portions 136 and 138 formed in the cylinder head 8 and is swingable around the axis, but is prevented from moving in the axial direction. . The standing wall portions 136 and 138 have bearing portions 124c,
A hole is formed at a position corresponding to the center hole of 126c, and the support pipe 130 is fixed therethrough. Therefore, the support pipe 130 is fixed to the cylinder head 8 and does not move or rotate in the axial direction.

Further, the control shaft 132 in the support pipe 130 penetrates the support pipe 130 slidably in the axial direction, and is connected to the auxiliary shaft 102 of the lift variable actuator 100 at one end side as shown in FIG. Has been done. Therefore, the first hydraulic chamber 106 and the second hydraulic chamber 107
By adjusting the hydraulic pressure to the control shaft 132
The axial displacement of the can be adjusted. As a result, the roller 122f of the input section 122 and the swing cam 12 are passed through the control shaft 132 and the slider gear 128.
It is possible to adjust the relative phase difference between the nose 124d of the No. 4,126 and the nose 124d of the No. 4,126. That is, by driving the variable lift amount actuator 100, the valve lift amounts of the intake valves 12a and 12b can be continuously varied as shown in FIGS.

Here, FIG. 9 shows a state of the intermediary drive mechanism 120 in a state where the control shaft 132 is moved to the limit in the H direction by the lift variable actuator 100. 9 to 11 show the second swing cam 126.
Shows the mechanism that drives the first intake valve 12a, but the mechanism that the first swing cam 124 drives the second intake valve 12b is also the same, so the first swing cam 124 and the second intake valve 12b are the same. Will also be described.

In the state of FIG. 9 (A), the base circle portion of the intake cam 45a (the portion excluding the nose 45c) is in contact with the roller 122f of the input portion 122 of the intermediary drive mechanism 120. Although not shown, the roller 122f is biased by a spring so as to always contact the intake cam 45a side. At this time, the noses 124d and 126d of the rocking cams 124 and 126 are not in contact with the rollers 13a of the rocker arm 13, and the noses 124d and 126d are not in contact with the rollers 13a.
The base circle portion adjacent to d is in contact. For this reason,
The intake valves 12a and 12b are closed.

The intake camshaft 45 is rotated and the nose 45c of the intake cam 45a is rotated by the roller 122f of the input section 122.
When is pushed down, the input unit 12 in the intermediary drive mechanism 120 is pressed.
Rocking cams 124, 1 from 2 via a slider gear 128
The swing is transmitted to 26. The swing cams 124 and 126 swing so as to push down the noses 124d and 126d.
Therefore, the curved cam surfaces 124e and 126e provided on the noses 124d and 126d immediately contact the rollers 13a of the rocker arm 13 to cover the entire range of the cam surfaces 124e and 126e as shown in FIG. 9B. The roller 13a of the rocker arm 13 is pushed down by using. As a result, the rocker arm 13 swings around the base end portion 13c side supported by the adjuster 13b, and the tip end portion 13d of the rocker arm 13 largely pushes down the stem end 12c. In this way, the intake valves 12a and 12b open the intake ports 14a and 14b with the maximum valve lift amount.

FIG. 10 shows a variable lift amount actuator 10.
0 shows the state of the intermediary drive mechanism 120 when the control shaft 132 is slightly returned in the L direction from the state of FIG.

In FIG. 10A, the base circle portion of the intake cam 45a is in contact with the roller 122f of the input section 122 of the intermediary drive mechanism 120. At this time, the swing cam 1
The noses 124d and 126d of 24 and 126 are not in contact with the roller 13a of the rocker arm 13, and the base circle portions slightly apart from the noses 124d and 126d are in contact with the rollers 13a of the rocker arm 13. Therefore, the intake valve 1
2a and 12b are closed. This is the intermediary drive mechanism 1
Since the slider gear 128 slightly moved in the L direction within the position 20, the roller 122f of the input unit 122 and the swing cam 124,
This is because the relative phase difference between 126 and the noses 124d and 126d has decreased.

The intake camshaft 45 rotates, and the nose 45c of the intake cam 45a rotates the roller 122f of the input section 122.
When is pushed down, the input unit 12 in the intermediary drive mechanism 120 is pressed.
Rocking cams 124, 1 from 2 via a slider gear 128
The swing is transmitted to 26. The swing cams 124 and 126 swing so as to push down the noses 124d and 126d.

As described above, in the state of FIG. 10A, the roller 13a of the rocker arm 13 has the nose 124d,
The base circle portion of the intake cam 45a which is separated from 126d is in contact. Therefore, even if the rocking cams 124 and 126 rock, the roller 13a of the rocker arm 13 remains for a while.
Is the curved cam surface 124 of the nose 124d, 126d
e, 126e is kept in contact with the base circle without touching. Then, the curved cam surface 124e,
126e contacts the roller 13a and pushes down the roller 13a of the rocker arm 13 as shown in FIG. 10 (B). As a result, the rocker arm 13 has the base end portion 13
Swing about c. However, since the roller 13a of the rocker arm 13 is initially separated from the noses 124d and 126d, the use range of the cam surfaces 124e and 126e is reduced. Therefore, the rocking angle of the rocker arm 13 becomes small, and the pushing down amount of the stem end 12c by the tip portion 13d of the rocker arm 13, that is, the lift amount becomes small. In this way, the intake valves 12a, 12b are moved to the intake ports 14a, 1 with a valve lift amount smaller than the maximum amount.
4b is opened.

FIG. 11 shows a variable lift amount actuator 10.
The state of the intermediary drive mechanism 120 in the state where the control shaft 132 is returned to the maximum L direction by 0 is shown.
In the state of FIG. 11A, the roller 1 of the rocker arm 13 is
The base circle portion of the intake cam 45a, which is largely separated from the noses 124d and 126d, is in contact with 3a. For this reason, the roller 13a of the rocker arm 13 is in full swing.
Is the curved cam surface 124 of the nose 124d, 126d
e, 126e is kept in contact with the base circle without touching. That is, as shown in FIG. 11B, even if the nose 45c of the intake cam 45a pushes down the roller 122f of the input portion 122 to the maximum extent, the curved cam surfaces 124e and 126e cause the roller 13 of the rocker arm 13 to move.
It is never used to push down a. As a result, the rocker arm 13 does not swing around the base end portion 13c, and the tip end portion 1 of the rocker arm 13 is prevented.
The amount by which the stem end 12c is pushed down by 3d, that is, the valve lift amount becomes "0". Thus, even if the intake camshaft 45 rotates, the intake valves 12a and 12b maintain the closed state of the intake ports 14a and 14b.

Thus, the lift amount variable actuator 1
By adjusting the axial position of the control shaft 132 with 00, the valve lift amount of the intake valves 12a and 12b can be continuously adjusted as shown by the solid curve in the graph of FIG.

When the intake valves 12a and 12b are opened, the valve spring 12d of the intake valves 12a and 12b moves in the direction of narrowing the angle between the arm 122c and the noses 124d and 126d via the rocker arm 13. Since a force acts, a thrust force that moves in the L direction is generated in the slider gear 128. Therefore, the thrust force Fs that tries to move the control shaft 132 in the L direction acts via the locking pin 132a. The larger the valve lift amount of the intake valves 12a and 12b, the larger the valve spring 12d.
The thrust force Fs generated on the control shaft 132 becomes stronger as the amount of movement in the H direction increases. That is, it becomes as shown in FIG.

According to this embodiment described above, the following effects can be obtained. In the variable valve operating device according to the present embodiment, the control shaft 132 is included in the lift amount variable actuator 100 that adjusts the axial position of the control shaft 132.
An assist spring 111 is provided to apply an assist force against the thrust force generated in the. The assist force of the assist spring 111 is set to be larger than the thrust force of the control shaft 132 on the low lift side of the control shaft 132. Further, the variable lift amount actuator 100 is provided with a lock pin 113 that restricts the movement of the control shaft 132 toward the high lift side by the assist force of the assist spring 111 when the hydraulic pressure is low. Therefore, the hydraulic pressure of the lift amount variable actuator 100 may be insufficient and fall below the biasing force of the assist spring 111 before the hydraulic pressure rises when the engine 2 is started and before the hydraulic pressure is reduced when the engine 2 is stopped. In this case, the lock pin 113 restricts the movement of the piston 104 to restrict the control shaft 132 from moving toward the high lift side, and holds the control shaft 132 at the low lift side to suppress the unstable operation. You can Therefore, the valve lift amount can be maintained at a predetermined value. Further, during normal operation of the engine 2, an assist force for assisting the movement of the control shaft 132 to the high lift side can be applied by the assist spring 111, so that the minimum operating hydraulic pressure of the lift amount variable actuator 100 is reduced to a small value. Therefore, the operation response of the control shaft 132 can be improved.

Further, when the control shaft 132 is moved to the high lift side, the lock spring 11 is moved.
6 against the urging force of the lock pin 113 of the second hydraulic chamber 10.
Third hydraulic chamber 11 for applying hydraulic pressure so as to escape from 7
4 is provided. Therefore, during normal operation of the engine 2, when the control shaft 132 moves toward the high lift side, the hydraulic pressure is supplied to the third hydraulic chamber 114, and the lock pin 113 resists the urging force of the lock spring 116 to generate the second hydraulic pressure. The piston 104 can be unlocked by exiting the chamber 107.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. In this embodiment, the intake valve 2
The valve amounts of 12a and 212b are adjusted by the lift amount variable actuator 100.
It is performed by moving the auxiliary shaft 102 as a control shaft, which is connected via the rolling bearing portion 250a, in the axial direction.

The intake camshaft 245 is interlocked with the rotation of the crankshaft of the engine via a timing sprocket (may be a timing gear or timing pulley) 252 provided at one end. However, since the auxiliary shaft 102 is connected to the intake camshaft 245 via the rolling bearing portion 250a, the intake camshaft 24
The auxiliary shaft 102 does not rotate in association with the rotation of 5. The auxiliary shaft 102 moves integrally with the intake cam shaft 245 only in the axial direction.

The timing sprocket 252 connected to the intake camshaft 245 is rotatably supported so as not to move in the axial direction with respect to the cylinder block of the engine. The connection by the straight spline mechanism 252a at the central portion allows the movement of the intake camshaft 245 in the axial direction.

The intake cam 245a provided on the intake cam shaft 245 is a three-dimensional cam whose profile continuously changes in the axial direction. Specifically, the intake cams 245a are formed so that the cam nose is low on the right side of the drawing and gradually increases toward the left side. Due to this change in profile, FIG.
The valve lift amount is variable in the same manner as shown in FIG.

The intake cam 245a, which is a three-dimensional cam, has the side on which the valve lift amount is increased as shown in the figure on the left side. Therefore, the restoring force received from the valve spring 212d of the intake valves 212a and 212b is the intake cam 2
Thrust force in the L direction is generated on the intake camshaft 245 by the cam surface of the reference numeral 45a. Then, as shown in FIG. 13, when the piston 104 is at the limit position in the L direction, the thrust force is small. Piston 10
4 is moved toward the limit position in the H direction, the valve springs 212 of the intake valves 212a and 212b.
The restoring force received from d increases and the thrust force also increases.

According to this embodiment described above, the following effects can be obtained. The variable valve operating device according to the present embodiment is a three-dimensional cam 245a.
And an auxiliary shaft (control shaft) 102. Also in this case, the movement of the piston 104 is restricted by the lock pin 113 and the movement of the auxiliary shaft 102 to the high lift side is performed before the hydraulic pressure rises when the engine 2 is started and before the hydraulic pressure is reduced when the engine 2 is stopped. Can be regulated to suppress unstable operation.

In the variable valve operating device of this embodiment, the auxiliary shaft 102 also serves as the cam shaft 245 of the three-dimensional cam. Even in this case, the movement of the piston 104 is restricted by the lock pin 113 to restrict the movement of the auxiliary shaft 102 toward the high lift side, and the auxiliary shaft 1 is prevented.
02 can be held on the low lift side, and unstable operation of the auxiliary shaft 102 can be suppressed.

The embodiment is not limited to the above, but may be modified as follows. In each of the above-described embodiments, the third hydraulic chamber 114 is formed in the vicinity of the lock pin 113, and hydraulic pressure is applied to the lock pin 113 to extract the lock pin 113 from the second hydraulic chamber 107. Instead of the third hydraulic chamber 114,
The lock pin 113 may be made of a magnetic material, an electromagnetic solenoid may be provided on the lock spring 116 side, and the lock pin 113 may be extracted from the second hydraulic chamber 107 based on the exciting force of the electromagnetic solenoid.

In each of the above embodiments, a plurality of lock pins 113 may be provided in the circumferential direction of the piston 104.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an engine and its control system according to a first embodiment.

FIG. 2 is an explanatory view of the configuration of a cylinder head portion of the same.

FIG. 3 is a cross-sectional view showing the internal structure of the variable lift amount actuator according to the first embodiment.

FIG. 4 is a sectional view showing an internal structure of the lift amount variable actuator.

FIG. 5 is a graph showing the relationship between thrust force and assist force and the stroke of the control shaft.

FIG. 6 is a perspective view showing a configuration of an intermediary drive mechanism of the first embodiment.

FIG. 7 is a partially cutaway perspective view showing the internal structure of the intermediate drive mechanism.

FIG. 8 is a shape explanatory view of a support pipe and a control shaft of the intermediary drive mechanism.

FIG. 9 is an explanatory diagram of a valve lift amount adjusting function by the intermediary drive mechanism of the first embodiment.

FIG. 10 is an explanatory diagram of a valve lift amount adjustment function of the intermediary drive mechanism of the same.

FIG. 11 is an explanatory diagram of a valve lift amount adjusting function of the intermediary drive mechanism in the same manner.

FIG. 12 is a graph showing a change in valve lift amount by the intermediary drive mechanism of the first embodiment.

FIG. 13 is a structural explanatory view of a variable valve mechanism according to the second embodiment.

[Explanation of symbols]

100 ... Lift amount variable actuator, 102 ... Auxiliary shaft (control shaft), 103 ... Cylinder,
104 ... Piston, 111 ... Assist spring (assist force applying means), 113 ... Lock pin, 114 ... Third
Hydraulic chamber, 116 ... Locking spring, 45, 245 ...
Cam shaft, 45a ... Cam, 49 ... Crank shaft, 120 ... Intermediary drive mechanism, 132 ... Control shaft, 245a ... Three-dimensional cam.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G016 AA08 AA19 BA28 BB14 BB17                       BB22 BB25 BB26 CA24 CA25                       CA27 CA29 DA01 DA04 DA06                       DA08 DA22 GA06                 3G018 AB04 AB12 AB17 BA04 BA10                       BA16 BA17 BA32 BA36 CA06                       CA09 CA18 CA19 DA10 DA13                       DA24 DA50 DA51 DA61 DA62                       DA63 DA83 FA02 FA06 FA07                       GA04

Claims (6)

[Claims] 1. A variable valve operating apparatus for an internal combustion engine, wherein a valve lift amount is continuously variable by interlocking with an axial position of the control shaft by moving the control shaft in the axial direction. A piston that is provided in a part of the control shaft and moves integrally with the control shaft by the hydraulic pressure supplied to the cylinder, and assists the control shaft in moving to the high lift side against the thrust force generated in the control shaft. A hydraulic actuator having an assisting force applying means for applying an assisting force for controlling, and setting the assisting force of the assisting force applying means on the low lift side of the control shaft to be larger than the thrust force of the control shaft, When the hydraulic pressure is low A variable valve operating system for an internal combustion engine, comprising lock means for restricting movement of the control shaft to a high lift side by a step assist force. 2. The lock means according to claim 1, wherein the lock means includes a lock pin protruding in a direction substantially orthogonal to an axial direction of the control shaft in the cylinder by an urging force of a lock spring.
A variable valve operating device for an internal combustion engine, wherein movement of the piston is restricted by engaging the lock pin with the piston. 3. The hydraulic device according to claim 2, wherein the lock means is configured to hydraulically move the lock pin against the urging force of the lock spring when the control shaft moves toward a high lift side so that the lock pin is pulled out of the cylinder. A variable valve operating system for an internal combustion engine, comprising a hydraulic chamber for operating 4. The camshaft according to claim 1, wherein the camshaft is driven to rotate by a crankshaft of an internal combustion engine, a cam provided on the camshaft, and rocks on an axis different from the camshaft. The intermediary drive mechanism, which is movably supported and has an input section and an output section, drives the valve at the output section when the input section is driven by the cam, and the movement amount in the axial direction of the intermediary drive mechanism is The control shaft that is interlocked with the relative phase difference between the input unit and the output unit, and the hydraulic actuator that adjusts the relative phase difference between the input unit and the output unit of the intermediary drive mechanism by moving the control shaft in the axial direction. And a variable valve operating device for an internal combustion engine, wherein the valve lift amount is continuously variable in association with the axial position of the control shaft. 5. A variable movement according to claim 1, wherein a valve lift amount is continuously variable by moving a three-dimensional cam whose cam profile changes in the axial direction in the axial direction. It is a valve mechanism, and the amount of movement of the control shaft in the axial direction is 3
A variable valve operating device for an internal combustion engine, which is interlocked with an axial movement amount of a three-dimensional cam. 6. The variable valve operating system for an internal combustion engine according to claim 5, wherein the control shaft also serves as a cam shaft of the three-dimensional cam.