JPH07150916A - Valve lift variable device of internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a valve lift variable device of an internal combustion engine, capable of effectively drawing out output of an engine by effectively making a valve system function at a low cost while making full use of characteristics of a zero-rush mechanism. CONSTITUTION:A valve lift variable device is provided with a hydraulic valve lifter 6 wherein one end is brought in contact with a cam 5, a rotational member (eccentric ring member) 12 provided with a tooth profile on the outer periphery, for holding the valve lifter 6 in the eccentric position so as to freely displace it, and to be rotatably supported by a housing 9, a lever member 8 wherein one end is supported by the housing 9 so as to be freely oscillated, and an actuator 16 for varying the valve lift through the lever member 8 by rotating the rotational member 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve lift varying device for an internal combustion engine, and more particularly to a valve lift of an internal combustion engine having an intake / exhaust valve driven by a cam provided on a cam shaft, depending on operating conditions. The present invention relates to a variable valve lift device that can be changed.

[0002]

2. Description of the Related Art As such a conventional valve lift variable device for an internal combustion engine, there is one disclosed in Japanese Patent Laid-Open No. 105005/1993. In this conventional example, a tapered surface is formed on a cam lobe provided on the cam shaft so as to have a three-dimensional cam surface, and an arm side tip in contact with the cam can be swung so that the cam shaft itself can be moved. The valve lift is made variable by displacing it in the axial direction.

[0003]

However, in the above-mentioned conventional example, a means for axially moving the camshaft driven by the crankshaft of the internal combustion engine is required, and moreover, the camshaft is rotating during rotation of the camshaft. In order to displace, for example, a spline mechanism is provided between the cam shaft driving pulley and the cam shaft, which causes abnormal noise due to backlash. Further, since the spline mechanism has some play, it may be worn or damaged, resulting in low reliability. Furthermore, since the cam transmits the driving force to the driven body side via the tapered surface, the component force acting in the axial direction of the reaction force becomes large, so that a large output is required for the actuator for displacing the cam shaft. There was a problem of being done.

An object of the present invention is to pay attention to the above-mentioned conventional problems, and to solve the problems, it is possible to effectively operate the valve operating mechanism at low cost while making the most of the characteristics of the zero lash mechanism. An object of the present invention is to provide a variable valve lift device for an internal combustion engine.

[0005]

In order to achieve the above object, the present invention provides a hydraulic valve lifter having one end kept in contact with a cam and displaceable in the valve axial direction of an intake valve or an exhaust valve, and an outer peripheral portion. A rotating member that has a toothed shape and that displaceably holds the valve lifter in an eccentric position and is rotatably supported by a fixed housing; and is interposed between the other end of the valve lifter and the valve shaft, A position where a swingable lever member whose one end is supported by the fixed housing is meshed with a tooth profile of the rotating member, and the rotating member is rotated to maintain contact with the lever member of the valve lifter. An actuator for changing the valve lift by displacing the lever member to change the swing amount by the lever member.

[0006]

According to the present invention, when controlling so that the valve lift can be obtained according to the operating state of the engine, the rotating member rotatably supported by the housing between the cam shaft and the valve shaft is used as the actuator. By rotating the rotary valve with the lever member, the relative position of the hydraulic valve lifter, which is held in the eccentric position of the rotary member so as to be displaceable in the valve axis direction, can be changed, and thereby the valve shaft that maintains contact with the lever member. The valve lift of can be made variable according to the change of the swing amount of the lever member. By freely changing the lift amount from low lift to high lift, the engine can efficiently output. it can.

[0007]

Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

1 and 2 show an embodiment of the present invention. In these figures, 1 is a cylinder head of the engine, 2 is a cam journal for supporting the cam shaft 3 on the cylinder header 1, 4 is a shaft retainer, and 5 is a cam provided on the cam shaft 3. 5 lifts the valve shaft 7 of the intake / exhaust valve incorporated in the cylinder head 1 via the hydraulic valve lifter (HVLA) 6. The mechanism for changing the lift according to the present invention will be described later. Here, the HVLA 6 of the present example has a disk-shaped table portion 6B that keeps contact with the cam 5 on the tappet body 6A, a plunger member 6C that slidably operates in the tappet body 6A, and a hydraulic pressure to which hydraulic pressure is introduced. Room 6
It is composed of an inner cylindrical portion 6E having a D and assembled along the inner surface of the plunger member 6C, a check valve 6F, a return spring 6G, and the like, and 6H is an oil introduction hole for guiding oil to the hydraulic chamber 6D. is there.

Reference numeral 8 denotes a lift variable lever (hereinafter simply referred to as a lever member) for keeping the end of the plunger member 6C of the HVLA 6 in contact. The HVLA 6 always functions to keep the valve clearance at zero. One surface of the eight end portions is in contact with the end portion of the plunger member 6C, and the other surface is in contact with the end portion of the valve shaft 7. Reference numeral 9 is a housing in which a variable lift mechanism is incorporated, and is fixed to the cylinder head 1 by a bolt 10. Reference numeral 11 denotes a support pin that supports the lever member 8 on the housing 9 so as to be swingable. Reference numeral 12 denotes a rotating member (hereinafter referred to as an eccentric ring member) fitted in the housing 9 concentrically with the valve shaft 7 and rotatably held, 12A denotes a tooth mold formed on the outer peripheral portion of the eccentric ring member 12, and 12B. And 12C transfer oil from the oil gallery 13 through the oil passage 9A provided in the housing 9 to the hydraulic chamber 6 of the HVLA 6.
It is an oil groove for leading to D, and oil is guided to the oil gallery 13 from an oil pump (not shown).

The HVLA 6 described above is slidably held in the eccentric ring member 12 in an eccentric state. Therefore, the HVLA 6 is in the state shown in FIGS. HVL)
The axis of A6 is eccentric to the base side of the lever member 8 from the center of the cam shaft 3 and the center of the valve shaft 7. 14 is
A retaining ring for rotatably holding the eccentric ring 12 in the housing 9, 15 a stopper for processing the oil passage 9A, and 16 teeth for rotating the eccentric ring member 12 by an actuator mechanism described later. A rack member that meshes with the mold 12A, and 17 is a retaining ring that supports the rack member 16 in the housing 9 so as to operate the rack member 16 in the direction orthogonal to the paper surface in FIG.

Next, the actuator mechanism of the variable lift device according to the present invention will be described with reference to FIG.

Here, 21 is a DC motor for driving the actuator mechanism, 22 is a worm gear driven by the DC motor 21, and 23A and 23B are worm gears 2.
2, a gear box and a box cover for accommodating the worm wheel 24 meshing therewith, 25 a ball bearing for axially supporting the worm wheel 24, 26 a sealing ring, and 27 a pickup for detecting the rotational movement of the worm wheel 24. , 24A is worm wheel 2
4 is a projection for detection that is provided so as to project from the side surface 4 toward the pickup 27. Further, 28 is an actuator for converting the rotational movement of the worm wheel 24 into a linear movement movement of the rack member 16 (hereinafter referred to as a movement conversion member), 28A is its male screw portion, and 28B is the end portion of the male screw portion 28. The pinion gear is rotatably supported by the rotary pin 28C.

The male screw portion 28A of the motion converting member 28 is screwed with the female screw portion 24A formed in the shaft hole of the worm wheel 24, and its pinion gear 28B is meshed with the rack teeth of the rack member 16. 29 is a rack member 1
A rack support member for slidably supporting 6 on a part of the cylinder head 1, and 30 is a fixed rack having a tooth type that meshes with the pinion gear 28B and fixed to a part of the cylinder head 1. . The DC motor 21 is connected to the ECU 3
It is driven by the control of No. 2, and the ECU 32 is input with information and data relating to the operating state such as the engine speed, cooling water temperature, and load, and based on these, the DC motor 21 is adjusted to adjust the valve lift. The actuator mechanism is driven by the worm wheel 24
The number of revolutions is fed back via the pickup 27 to control the valve lift.

FIG. 4 shows a variable operation of the valve lift according to the present invention. As shown in FIGS. 1 and 2, (A) shows a state in which the HVLA 6 is held on the base side of the lever member 8 by the engagement of the eccentric ring member 12 that slidably holds the HVLA 6 with the rack member 16. When the cam 5 is driven in such a state, the valve shaft 7 can be operated with a high lift through the lever member 11 by moving the HVLA 6 from the broken line to the position shown by the solid line.

From the state (A), for example, the DC motor 21 is normally rotated to rotate the worm wheel 24 meshing with the worm gear 22, and the rack member 16 is moved through the motion converting member 28 as shown in FIG. When the rack member 16 is moved in the direction of the arrow A, the rack member 16 can be moved by twice the movement conversion member 28. Then, the eccentric ring member 12 that meshes with the rack teeth of the rack member 16 is rotated in the housing 9 by such movement of the rack member 16 (see FIG. 1 and FIG. 2 above), and the HVLA 6 is moved to FIG. 4B. As shown in, the lever member 11 can be displaced to a position where it keeps contact with the tip end side.

In the state shown in FIG. 4B, as the cam 5 rotates, the HVLA 6 slides from the broken line to the position indicated by the solid line, and the valve shaft 7 is lifted accordingly. Since the plunger member 6C of the HVLA 6 comes into contact with the tip of the member 11, the valve shaft 7 can be operated with a low lift. Further, by controlling the eccentric ring member 12 to rotate to an intermediate state between FIGS. 4A and 4B, a medium lift can be obtained.

In the above-described embodiment, the lift of each valve shaft is changed by each actuator mechanism for each intake / exhaust valve. However, as shown in FIG. 5, one DC step is required. The motor 21 drives a plurality of worm gears 24 via a universal joint 33, and the individual worm wheels 24 simultaneously change the lift of, for example, an intake valve (not shown) in one cylinder 34A of the engine 30 and the intake air of the other cylinder 34B. It is also possible to change the lift of the valve at the same time.

FIG. 6 shows a second embodiment of the present invention. In this embodiment, the actuator mechanism has a configuration different from that of the first embodiment. Here, 41 is a fixed shaft (wheel shaft) of the worm wheel 24, 42 is a thrust receiving collar portion provided on the wheel shaft 41, and 43.
Is a worm gear. In the case of this example, since the wheel shaft 41 receives axial thrust by the forward and reverse rotation of the worm wheel 24, the journal 2 that also supports the wheel shaft 41 and its shaft retainer 44 have a structure as a thrust bearing. It is incorporated. Further, a tooth profile 12D for a worm wheel corresponding to the worm gear 43 is formed on the outer peripheral portion of the eccentric ring member 12 that meshes with the worm gear 43.

Therefore, in the variable valve lift device having such an actuator structure, the DC motor 2 is used.
The worm wheel 24 and its wheel shaft 41 are rotated in either direction through the worm gear 22 by the forward / reverse rotation by 1, and the eccentric ring member 12 is rotated by the rotation operation, and the above-described first embodiment is performed. The valve lift can be changed in the same manner as.

According to the present embodiment, the structure of the actuator is simplified, and the variable valve lift mechanism provided on the cylinder head is directly driven by the drive shaft of the actuator mechanism.
The horsepower of the motor can be reduced and the cost can be reduced, which contributes to downsizing of the entire device.

FIG. 7 shows a third embodiment in which the valve lifts of both intake valves and exhaust valves (not shown) are simultaneously changed by one step DC motor 21. That is, 3A and 5A are cam shafts and cams for driving the intake valve, 3B and 5B are cam shafts and cams for driving the exhaust valve, 41A has a worm gear 43A and a flange 42A on the intake valve side, and an end part. Is a shaft to which a spur gear 45A is attached, and 41B is a shaft that has a worm gear 43B and a flange portion 42B on the exhaust valve side and has a spur gear 45B attached to an end thereof. Reference numeral 46 is an idle gear coaxial with the step DC motor 21, and the idle gear 46 can rotate the shafts 41A and 41B in opposite directions, for example, at the same speed by meshing with spur gears 45A and 45B, respectively. . Reference numeral 47 is a gear casing, and 48 is a motor mounting seat fixed to the gear casing 47.

In the variable valve lift device constructed as described above, the step DC motor 21 is driven by the drive signal from the ECU 32 when the lift is changed, and the shaft 41A is driven.
And 41B are rotated simultaneously, the eccentric ring member 12 on the intake valve side and the eccentric ring member 12 on the exhaust valve side can be simultaneously rotated in the same direction or opposite directions via the worm gears 43A and 43B, and the lifts of both valves can be simultaneously changed. . 12DA is an eccentric ring member 12 on the intake valve side.
A tooth profile is formed on the outer peripheral portion and meshes with the worm wheel 43A, and 12DB is a tooth profile formed on the outer peripheral portion of the eccentric ring member 12 on the exhaust valve side and meshes with the worm wheel 43B.

FIG. 8 shows the structure of an actuator according to the fourth embodiment of the present invention. In this example, the rack member 1 is hydraulically operated.
6 is driven to rotate the eccentric ring member 12 to change the valve lift. In FIG. 8, reference numeral 38 denotes the first piston portion 38A, the pinion gear 38B, and the pinion gear 38B.
8A is a first motion converting member composed of a rotary pin 38C pivotally supported and connected to the end of 8A, 39 is a second motion converting member formed in a piston shape, and 40 is a first motion converting member 38.
It is a cylinder member having a two-stage cylinder chamber that keeps the piston portion 38A and the second piston portion 39A of the second motion converting member 39 slidable.

The second motion converting member 39 is divided into a first hydraulic chamber 51 between the crown of the first piston 38A and a second hydraulic chamber 52 between the top of the cylinder by the second piston 39A. It defines the cylinder chamber. 51A is an oil introduction port to the first hydraulic chamber 51, 52A is an oil introduction port to the second hydraulic chamber 52, and the oil introduction ports 51A and 52A
The oil pressure is supplied to the oil pump 61 via electromagnetic switching valves 62 and 63, respectively. The electromagnetic switching valve 6
ECs 2 and 63 are used when the valve lift is variable, which will be described later.
The switching operation is controlled by U32.
Reference numeral 64 denotes a spring that biases the first piston portion 38A of the first motion converting member 38 toward the stepped portion 40A of the cylinder,
Reference numeral 65 is an air vent hole, 66A and 66B are stopper rings, 67 is an O-ring for sealing provided between the cylinder member 40 and the cylinder head 1, and 68A and 68B are the first piston portion 38A and the second piston portion. It is a seal ring provided around 39A.

In the variable valve lift device thus constructed, the eccentric ring member 12 and the HVLA 6 are arranged as shown in FIG.
In the state of high lift maintained in the position shown in (1), the first piston portion 38A of the first motion converting member 38 is biased toward the stepped portion 40A of the cylinder member 40 by the spring force of the spring 64, and The second piston portion 39A of the second motion converting member 39 is maintained in a state in which the cylinder chamber on the crown surface side of the first piston portion 38A is defined by the first hydraulic chamber 51 and the second hydraulic chamber 52.

The operating condition of the engine is the ECU 32.
When it is detected that the valve lift is to be maintained at the middle level, the ECU 32 controls the electromagnetic control valve 63 to open, so that the hydraulic pressure is supplied to the second hydraulic chamber 62. The second piston portion 39A of the second motion converting member 39 is slid leftward in FIG. 8 so that the rod portion 39B of the member 39 is moved to the first piston portion 38A.
Is pressed to slide the first motion converting member 38 in the same direction against the spring force of the spring 64. Thus, the above operation is performed until the second piston portion 39A comes into contact with the stopper member 66B, and the pinion gear 38 of the second operation converting member 38 is performed.
The rack member 16 is moved to the left by B in the same manner as described in the first embodiment, and the eccentric ring member 12 is rotated to control the valve lift via the lever member 8 so as to keep the valve lift at the middle position. It

Further, when a low lift is required, the solenoid control valve 62 is switched to open in the above state to supply the hydraulic pressure to the first hydraulic chamber 51. By such control, the first piston portion 38A is further moved to the left, and the valve lift can be maintained at a low lift as shown in FIG. 4B in a state where the first piston portion 38A is brought into contact with the stopper 66A. . By controlling the electromagnetic control valve 52 to open from the high lift state as shown in FIG. 8, the hydraulic pressure is supplied to the first hydraulic chamber 51, and the valve lift is changed from the high lift to the low lift all at once. It is also possible to change it, and in this case, it is also possible to control the electromagnetic control valve 63 so that its variable speed is increased by switching the electromagnetic control valve 63 to open simultaneously. Further, when the low lift is changed to the medium lift or the high lift, the reverse control described above is performed.

According to the present embodiment, the valve lift can be varied in multiple stages by utilizing the oil pressure of the oil pump driven by the engine, and the actuator mechanism has a simple structure, and the output of the engine is inexpensive and efficient. It is possible to provide a valve lift varying device for an internal combustion engine that contributes to pulling out the valve.

[0029]

As described above, according to the present invention, the hydraulic valve lifter, which has one end kept in contact with the cam and which can be displaced in the valve axis direction of the intake valve or the exhaust valve, and the tooth profile on the outer peripheral portion. A rotating member that holds the valve lifter in an eccentric position so as to be displaceable and is rotatably supported by a fixed housing; and is interposed between the other end of the valve lifter and the valve shaft, and one end of which is A swingable lever member supported by a fixed housing is meshed with a tooth profile of the rotating member, and the rotating member is rotated to displace a position of the valve lifter that maintains contact with the lever member. An actuator that changes the amount of rocking by the lever member to make the valve lift variable is provided, so that the valve lift can be made variable in multiple stages or continuously. It is possible to pull out the output efficiency, since the reaction force of the useless valve system can be prevented from acting, contributing to improved fuel economy. Also, HVL
By incorporating A, it becomes unnecessary to adjust the valve clearance, which contributes to the reduction of maintenance cost. Furthermore, since the variable valve lift mechanism can be integrated into the cylinder head for the intake valve and the exhaust valve, it can be installed at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration example of a valve lift variable mechanism according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the variable valve lift mechanism shown in FIG. 1 by a top view (A) and a partially crushed side view (B).

FIG. 3 is a cross-sectional view showing a configuration example of an actuator mechanism according to the first embodiment of the present invention.

FIG. 4 is an explanatory view showing a variable lift operation of the variable valve lift device of the present invention in a high lift state (A) and a low lift state (B).

FIG. 5 is an explanatory diagram schematically showing an application example of the variable valve lift device of the present invention.

FIG. 6 is a cross-sectional view (A) showing a structure according to a second embodiment of the present invention.
FIG. 3B is an explanatory diagram shown by a cross-sectional view (B) taken along the line AA of FIG.

FIG. 7 is a top view showing a partially crushed structure according to a third embodiment of the present invention.

FIG. 8 is a sectional view showing a configuration example of an actuator mechanism according to a fourth example of the present invention.

[Explanation of symbols]

 1 Cylinder Head 2 Cam Journal 3 Cam Shaft 4 Shaft Presser 5 Cam 6 Hydraulic Valve Lifter (HVLA) 6A Tappet Body 6B Table Part 7 Valve Shaft 8 Lift Variable Lever (Lever Member) 9 Housing 12 Eccentric Ring Member (Rotating Member) 13 oil gallery 16 rack member 21 DC motor 22 worm gear 24 worm wheel 24A female screw part 27 pickup 28 motion conversion member (actuator) 28A male screw part 28B pinion gear 32 ECU 38 first motion conversion member 38A first piston part 39 second motion conversion Member 39A Second piston part 40 Cylinder member 41 Wheel shaft 43, 43A, 43B Worm gear 45A, 45B Spur gear 46 Idle gear 51, 52 Hydraulic chamber 62, 63 Electromagnetic switching valve 64 Spring

Claims (4)

[Claims] 1. A hydraulic valve lifter, one end of which is in contact with a cam and which can be displaced in a valve axis direction of an intake valve or an exhaust valve, and a tooth profile on an outer peripheral portion, the valve lifter being displaceably held in an eccentric position. And a rotating member rotatably supported by the fixed housing, and interposed between the other end of the valve lifter and the valve shaft,
A position where a swingable lever member whose one end is supported by the fixed housing is meshed with a tooth profile of the rotating member and the rotating member is rotated to maintain contact with the lever member of the valve lifter. A valve lift varying device for an internal combustion engine, comprising: an actuator that is displaced to change a swing amount by the lever member to change a valve lift. 2. The rack member, wherein the actuator meshes with a tooth profile of the rotating member and is movable in a cam shaft direction,
The valve lift for an internal combustion engine according to claim 1, further comprising: a rotary gear driven by a stepping motor; and a motion conversion means for converting a rotary motion of the rotary gear into a moving motion of the rack member. Variable device. 3. The actuator includes a worm gear that meshes with a tooth profile of the rotating member to rotate the rotating member, and a gear that is coaxial with the worm gear and is driven by the stepping motor. The valve lift varying device for an internal combustion engine according to claim 1, wherein 4. The rack member, wherein the actuator meshes with a tooth profile of the rotating member and is movable in a cam shaft direction,
The valve lift varying device for an internal combustion engine according to claim 1, further comprising a plunger that is driven in multiple stages by hydraulic pressure to move the rack member in the same direction.