JPS61232314A - Valve driving apparatus for internal-combustion engine - Google Patents

Abstract

PURPOSE:To independently vary the opening and closing timing of intake and exhaust valves by opening and closing the intake and exhaust valves by the fluid pressure pressurized in a plurality of pressurizing means and independently varying the opening and closing timing for a plurality of relief passages. CONSTITUTION:When a cam shaft 4 and valve opening and closing cam 5 and 6 turn, accompanied with the revolution of a crankshaft 1, a plunger 10 for opening valve rises. Then, the first relief port 14 is closed, and the pressure in a pressurizing chamber 8 for opening valve increases, and working oil flows into the first pressure chamber 23 through the first communication passage 25. Then, a piston 22 lowers, and an intake and exhaust valve 20 starts valve opening operation. When the valve opening time of the intake and exhaust valve 20 is varied, the plunger 10 for opening valve is turned through a pinion 16 by operating a control rack 18. Therefore, the relative position between the notched part 10a of the plunger 10 for opening valve and the first relief port 14 is varied, and the lift timing on the start of pressurization into the pressurizing chamber 8 for opening valve is varied.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a valve drive device for an internal combustion engine.

(Prior Art) Conventional examples of valve drive devices for internal combustion engines include those shown in FIGS. A, E,
(See paper no. 840340).

is transmitted to an exhaust valve (not shown). The tappet 33 includes a sliding block 34 whose upper flat surface 34a abuts against the cam 32, and a lower end protrusion 34a of the sliding block 34 is seated on a seating portion 35a of a bearing saddle 35. The guide portion 35b of the bearing saddle 35 is inserted into a semi-cylindrical sliding seat portion 36a formed in the cylinder head 36, and the bearing saddle 35 is inserted into a semi-cylindrical sliding seat portion 36a formed in the cylinder head 36.
5 is adapted to be restricted from rotating around its axis.

Further, the bearing saddle 35 includes a pair of tabs 37a projecting from the top of the cylindrical cup 37.

37b, and the cup 37 is attached to the cylinder head 36 so as to be freely movable in the vertical direction in FIG.

As the cam 32 rotates, the tappet 33 is moved vertically in FIG. 3 to open and close the intake and exhaust valves. Further, by moving the camshaft 31 and the cam 32 in the left-right direction in FIG. 3, the lift amount and opening/closing timing of the intake/exhaust valves are changed.

In addition, 38 is the tappet 3 attached to the upper part of the cup 37.
This is a disc that adjusts the play of No. 3.

<Problems to be Solved by the Invention> However, in such a conventional valve drive device, the contour of the cam 32 is changed by moving the camshaft 31 in the left-right direction, and the intake/exhaust valves are controlled via the tappet 33. Since the lift amount and the valve opening/closing timing are changed, the opening/closing timing of the intake/exhaust valves is regulated by the shape of the cam 32, and the valve opening timing and valve closing timing can be changed independently. I couldn't do it. Additionally, since the cam shape is limited, there is little freedom and it is not possible to change the lift amount of the intake/exhaust valves and the opening/closing timing according to the engine operating conditions, making it impossible to bring out the maximum performance of the engine. could not.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a valve drive device for an internal combustion engine that can independently change the opening timing and closing timing of intake and exhaust valves. do.

Means for Solving the Problems> For this reason, the present invention utilizes a pair of cams each driven by the output shaft of the engine and a plunger that is linked to the movement of these cams to pressurize the incompressible fluid in the pressurizing chamber. a pair of pressurizing means for pressurizing; a fluid pressure cylinder having first and second pressure chambers defined by a piston and driving an intake valve or an exhaust valve to open and close; pressurizing the first pressure chamber and the one of the pressure chambers; a first communication path that communicates with the chamber, a second communication path that communicates the second pressure chamber with the other pressurizing chamber, and first and second communication paths that communicate with the pressure chambers of the pair of pressurizing means, respectively. a pair of opening/closing means for opening and closing the first and second relief passages according to the plunger position; and a pair of opening/closing means for opening and closing the first and second relief passages according to the plunger position; A pair of opening/closing timing changing means for respectively changing the opening/closing timing is provided.

In this way, the piston of the pressure cylinder is operated by the fluid pressure pressurized by the first and second pressurizing means to perform suction and
The opening and closing timings of the intake and exhaust valves are independently changed by driving the exhaust valve to open and close and independently changing the opening and closing timings of the first and second relief passages. I made it possible to do this.

<Example> An example of the present invention will be described below with reference to FIG.

In the figure, the crankshaft 1 is the output shaft of the engine.
A driven gear 3 is meshed with a drive gear 2 attached to an end of the camshaft 4, and an end of a camshaft 4 is attached to the driven gear 3. A valve-opening cam 5 and a valve-closing cam 6 are attached to the camshaft 4, and the valve-opening cam 5 and the valve-closing cam 6 are configured to rotate once for every two revolutions of the crankshaft l. ing.

In the cylinder head 7, hollow pressure chambers 8,9 for opening and closing the valves are formed in parallel with each other with their ends open. Cylindrical valve-opening and valve-closing plungers 10 and 11, respectively, as pressurizing means are first
Plunger 10.11 can slide freely in the vertical direction in the figure.
It is mounted so that it can rotate freely around the axis. The lower end surfaces of the valve-opening and valve-closing plungers 10.degree. 11 are pressed against the cam surfaces of the valve-opening and valve-closing cams 5 and 6 by the biasing force of springs 12 and 13 and abut. Further, a notch 10a is provided on the outer peripheral wall of the upper end of the plunger 10.11 for opening and closing the valve.

11a are formed, and these notches lQa and lla are formed so as to be inclined so as to gradually become longer in the axial direction of the plunger 10.11 with respect to the rotational direction of the plunger 10.11.

First and second relief ports 14.15 are formed in the outer wall of the pressurized chamber 8.9 for opening and closing the valve, penetrating the wall, and these relief ports 14.15 communicate with a low pressure source. The first and second relief passages, not shown, are connected to each other. Here, the valve opening and valve closing plungers 10.
11 is at the lowest position in FIG.
The first and second relief boats 14 are opened at 15.
．． 15 is formed.

Moreover, cylindrical first and second sleeves 16.17 are provided on the outer wall of the pressurizing chamber 8.9 for opening and closing the plunger 1.
The pinion gears 16a are attached to the outer walls of the first and second sleeves 16 and 17, respectively, and are attached to the outer walls of the first and second sleeves 16 and 17.
, 17a are formed respectively. Additionally, grooves 16b are provided at the ends of the first and second sleeves 16,17.

17b are formed, and pins 10b and 11b protruding from the side walls of the valve-opening and valve-closing plungers to and ii are engaged with these grooves 113b and 17b.

The binion gears 16a, 17a are meshed with control racks 18.19 for valve opening timing control and valve closing timing control, respectively, and the linear movement of these control racks 18.19 causes the first and second sleeves 16.17 and the plunger 10. 11 is rotated about the axis of the plunger 10.11 to change the relative positions of the lower end edges of the notches 10a, lla and the first and second relief boats 14.15.

Further, a hydraulic cylinder 21 as a fluid pressure cylinder for driving the opening/closing valve of the intake/exhaust valve 20 is integrally provided in the cylinder head 7, and the hydraulic cylinder 21 has first and second pressures defined by a piston 22. Chambers 23 and 24 are provided. A valve shaft of the intake/exhaust valve 20 is attached to the piston 22. The first and second pistons 22
A plurality of plate-shaped vanes m22a extending in the radial direction of the piston 22 are attached to both end faces facing the pressure chambers 23, 24. The cylinder head 7 includes a first communication passage 25 that communicates the first pressure chamber 23 with the valve-opening pressurizing chamber 8, and a first communicating passage 25 that communicates the second pressure chamber 24 with the valve-closing pressurizing chamber 9. A two-way communication path 26 is formed, and a first and second communication path 25
．． The center of the flow path 26 is offset from the center of the first and second pressure chambers 23,24.

Further, an oil supply passage 28 is formed in the cylinder head 7 to supply oil supplied from a constant pressure source 27 to the first and second pressure chambers 23,24. This oil supply passage 28 communicates with the second pressure chamber 24 when the piston 22 is at the highest position in FIG. 1, and communicates with the first pressure chamber 23 when the piston 22 is at the lowest position in FIG. It is formed.

The control racks 18 and 19 are driven by a drive device (not shown) such as a linear motor, a step motor, or a link mechanism. Note that FIG. 1 shows the configuration for one of the intake/exhaust valves 20. For example, in a four-cylinder internal combustion engine, one
If each cylinder has one exhaust valve and one intake valve, eight sets of devices shown in FIG. 1 are required. However, camshaft 4. Constant pressure source 27 and control racks 18, 19 can be used in common.

Here, the outer walls of the valve-opening and valve-closing plungers 10.11 constitute opening and closing means for opening and closing the first and second relief boats 14.15, and the notches 10a, lla.

The control rack 18.19 and the first and second sleeves 16.17 constitute opening/closing timing changing means for independently changing the opening/closing timing of the relief passage.

Next, the operation will be explained with reference to FIG.

First, when the intake/exhaust valve 20 is closed, as shown in FIG. 2a, the piston 22 is brought to the top position, and both the valve opening plunger 10 and the valve closing plunger 11 are brought to the bottom position in FIG. It will be brought. At this time, the pressurized chamber 8 for opening and closing the valve
, 9 are both in communication with the first and second relief boats 14.15, the pressure chambers 8.9 for opening and closing the valves have approximately atmospheric pressure. Therefore, since hydraulic oil flows from the constant pressure source 27 through the oil supply passage 28 and the second pressure chamber 24 into the valve-closing pressurizing chamber 9, the piston 22 is urged upward in FIG. 1 by the pressure of the hydraulic oil. The intake/exhaust valve 20 is maintained in a closed state.

When the camshaft 4 and the valve-opening and valve-closing cams 5 and 6 rotate with the rotation of the crankshaft 1, the valve-opening plunger 10 starts to lift upward in FIG. During this lift, during the period when the valve opening pressurizing chamber 8 and the first relief bow eye 4 are communicating through the notch 10a, the valve opening pressurizing chamber 8
Since a part of the hydraulic oil flows out via the first relief boat 14, the pressure in the valve opening pressurizing chamber 8 does not increase.

Then, when the valve-opening plunger 10 further lifts and the first relief port 14 is closed by the valve-opening plunger 10, the pressure in the valve-opening pressurizing chamber 8 starts to rise, and the hydraulic oil flows through the first communication passage 25. The air flows into the first pressure chamber 23 through the air. As a result, the piston 22 moves downward as shown in FIG. 2, and the opening operation of the intake/exhaust valve 20 begins. At this time, since the flow path center of the first communicating passage 25 is offset from the axis of the piston 22, the pressurized hydraulic oil becomes a jet and collides with the vane 22a at the top of the piston 22, causing the piston 22 to
Since the piston 22 moves downward while rotating, the downward movement of the piston 22 is stabilized, and the suction/exhaust valve 20 is prevented from hitting the valve seat of the intake/exhaust valve 20 unevenly.
can prevent uneven wear.

After the oil supply passage 2 is closed by the piston 22 due to the downward movement of the piston 22 as shown in FIG. 2C, the upper part of the oil supply passage 28 is closed to the first pressure chamber 23 as shown in FIG.
The piston 22 communicates with the second communication path 2.
The opening area of No. 6 to the second pressure chamber 24 is reduced. Therefore, a part of the hydraulic oil flowing into the first pressure chamber 23 escapes into the oil supply passage 28, and the hydraulic oil flowing into the second communication passage 26 from the second pressure chamber 24 decreases. As the pressure increases, the downward movement speed of the piston 22 gradually decreases, which softens the impact of the piston 22 against the lower end of the cylinder. When the piston 22 collides with the lower end of the cylinder (FIG. 2 e), the piston 22 rebounds as shown in FIG. is reduced, the first pressure chamber 23
The pressure increases, and the rebound of the piston 22 is suppressed.

Thereafter, while the valve opening plunger 10 is moving upward in FIG. 1, hydraulic oil flows into the first pressure chamber 23, but a portion of this hydraulic oil flows into the oil supply passage as shown in FIG. Escape to 28. Then, when the valve opening plunger 10 starts to move downward, the hydraulic oil in the oil supply passage 28 flows into the first communication passage 25 via the first pressure chamber 23 as shown in the second diagram. Therefore, the piston 22 is urged downward by the hydraulic oil pressure in the first pressure chamber 23, and the intake/exhaust valve 20 is maintained in the open state.

In this way, the opening operation of the intake/exhaust valve 20 is performed.

Thereafter, when the camshaft 4 further rotates, the valve-closing plunger 11 starts to move upward, and the hydraulic oil in the valve-closing pressurizing chamber 9 is introduced into the second pressure chamber 24 via the second communication passage 26 . As a result, the piston 22 starts moving upward, and the closing operation of the intake/exhaust valve 20 is performed in the same manner as the opening operation.

Next, control of the opening/closing timing of the intake/exhaust valves 20 will be explained. For example, to change the opening timing of the intake/exhaust valve 20, move the valve opening timing control control rack 18 in the left-right direction in FIG. 1, and the pinion 16 will rotate around the axis of the valve opening plunger lO. This rotational force is transmitted to the valve opening plunger 10 via the pin fob, and the valve opening plunger IO also rotates. As a result, the notch 10a formed in the outer circumferential wall of the valve opening plunger 10 is formed at an angle, so that
The lower edge of the notch 10a and the first relief port 14
The relative position with the

Therefore, since the valve-opening plunger 1o closes the first relief port 14 at a lift timing different from that before movement of the control rack 18, the lift timing at the start of pressurization of the valve-opening pressurizing chamber 8 changes, and the valve opening from the pressurized chamber 8 to the first pressure chamber 2
3, the lift position at the time when the hydraulic oil starts to be pumped changes. Therefore, the opening timing of the intake/exhaust valve 20 can be changed.

Further, regarding the valve closing timing control of the intake/exhaust valve 20, by moving the valve closing control rack 19 in the left and right direction in FIG. and 21st J Reef Boat 15
By changing the relative position of the valve-closing pressurizing chamber 9 to the second pressure chamber 24, the lift position at the time when hydraulic oil starts to be pumped from the valve-closing pressurizing chamber 9 to the second pressure chamber 24 changes, and the closing timing of the intake/exhaust valve 20 changes. I can do it.

In this way, by moving the control rack 18, 19, the opening timing and closing timing of the intake/exhaust valve 20 can be changed independently according to the engine operating condition, so that the engine capacity can be brought out to the maximum. In addition, since the hydraulic oil in the pressurizing chamber 8.9 is pressurized by a separate plunger 10.11, the hydraulic pressure for opening and closing the valve can be secured with a small amount of hydraulic oil. Opening/closing control of the exhaust valve can be performed without causing any delay in opening/closing control of the exhaust valve.

In addition, in this embodiment, the valve opening and valve closing plungers 10.1
The opening/closing timing of the first and second relief boats 14 and 15 is changed by changing the relative position between the lower end edge portions of the notches lQa and lla formed in the first and second relief boats 14 and 15. However, instead of the notches lQa and tta, as in the plunger of a sub-type fuel injection pump, for example, an inclined groove communicating with the pressurizing chamber may be provided in the side wall of the plunger.

<Effects of the Invention> As explained above, the present invention performs the opening and closing operations of the intake and exhaust valves using incompressible fluids pressurized by separate pressurizing means. Since the timing at which the fluid in the pressurizing chamber of the pressurizing means is changed independently according to the plunger operation, the opening timing and closing timing of the intake and exhaust valves can be adjusted depending on the engine operating state. It can be changed independently according to the situation, thereby maximizing the capabilities of the institution.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram of the same operation as above, Fig. 3 is a sectional view showing a conventional example of a valve drive device for an internal combustion engine, and Fig. 4 is a diagram showing the same as the above. This is an exploded view of the main parts.

Claims (1)

[Claims] a pair of cams each driven by the output shaft of the engine; a pair of pressurizing means that pressurizes the incompressible fluid in the pressurizing chamber by a plunger interlocked with the operation of these cams; and a first pressurizing means defined by a piston. and a fluid pressure cylinder that has a second pressure chamber and opens and closes an intake valve or an exhaust valve, a first communication passage that communicates the first pressure chamber and the one pressurizing chamber, and the second pressure chamber. and a second pressurizing chamber that communicates with the other pressurizing chamber.
a communication passage, first and second relief passages communicating with the pressure chambers of the pair of pressurizing means, and a pair of opening/closing means for opening and closing these first and second relief passages according to the plunger position; A valve drive device for an internal combustion engine, comprising: a pair of opening/closing timing changing means for changing the relative position of the plunger and the relief passage to change the opening/closing timing of the first and second relief passages, respectively.