JPS6120689B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hydraulic valve lift device for an internal combustion engine;
In particular, it relates to something that alleviates the impact force when the valve is seated.

Conventionally, various methods have been proposed for making the valve lift timing of a four-stroke engine variable depending on the engine load or engine speed. One of them is basically the same system as the oil tappet, but a hydraulic chamber is formed between the plunger engaged with the push rod and the lifter body that contacts the cam, and the oil in the hydraulic chamber is drained through a throttle hole. A system has been proposed in which the volume of the hydraulic chamber is reduced by allowing the hydraulic fluid to escape to the outside, thereby varying the lift amount of the plunger.

According to the conventional device of this type, the cam shape can be a two-dimensional original shape, and the structure can be simplified because there is no need to change the relative position of the camshaft and the plunger. Because of the structure that allows the amount of valve lift to be varied by releasing the valve, it is not possible to use a buffer curved section that reduces the valve seating speed when the intake and exhaust valves are seated, unlike cams commonly used in engines. There is a problem in that a very large impact force is generated when the valve is seated, producing a loud noise and at the same time causing problems in terms of the durability of the valve mechanism.

The present invention has been made in view of the above circumstances, and includes a lifter body that is slidably inserted into a cylinder body of a housing and is actuated by a cam of a camshaft, and a lifter body that is slidably inserted into the lifter body. The hydraulic type has a plunger that is actuated by a change in the hydraulic pressure in the hydraulic chamber and transmits the movement of the cam to the intake and exhaust valves, and the lift amount of the intake and exhaust valves is made variable by releasing the oil in the hydraulic chamber to the outside. The valve lift device is equipped with a brake chamber for applying a hydraulic brake when the intake and exhaust valves are seated, and is also equipped with a means to control the hydraulic pressure in the brake chamber, which allows the engine to rotate from low speeds to high speeds. This system applies smooth braking force to the intake and exhaust valves to reduce impact, and by controlling the brake chamber hydraulic pressure of the hydraulic valve lift device for each cylinder of the engine using a common hydraulic circuit, the intake and exhaust valves of each cylinder are controlled. This allows uniform braking force to be applied to the exhaust valve. Furthermore, according to the present invention, when the intake and exhaust valves are operated in the same manner as the cam profile without letting the oil in the hydraulic chamber escape to the outside, this can be done by releasing the hydraulic pressure in the brake chamber. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. In the first embodiment shown in FIGS. 1 to 3, 1 is a camshaft, on which a cam 1a is formed,
It is rotationally driven in synchronization with the crankshaft (not shown) of an OHV type 4-stroke engine. A cylindrical lifter body 5 is slidably fitted into a cylinder bore 4 of a housing 3 fixed to a cylinder block (not shown) of the engine. The end surface of the lifter body 5 is in contact with the cam 1a of the camshaft 1, and a substantially cylindrical plunger 6 is slidably fitted into the inner peripheral portion of the lifter body 5.

A flange portion 7 is formed at the end portion (upper end in the figure) of the plunger 6, and this flange portion 7
It is formed in the upper part of the cylinder bore 4 and is fitted into a cylinder bore 8 having a larger diameter. A flange portion 9 is also formed at the lower end of the cylinder bore 8, and this flange portion 9, the flange portion 7 of the plunger 6, and the cylinder bore 8 hold oil that applies a braking force to the plunger 6 when the plunger is lowered. Ring-shaped brake chamber 1
0 is formed.

Housing 3 includes an oil pump (not shown)
An oil supply port 11 through which oil is supplied is formed, and this oil supply port 11 communicates with a ring-shaped oil supply groove 12 formed on the inner periphery of the housing 3. The plunger 6 has an oil supply groove 1.
Four long hole-shaped oil supply holes 13 are formed which are always in communication with the oil supply groove 12 and the oil supply chamber 14 in the plunger 6 through these oil supply holes 13. A slit 15 is formed in one of the oil supply holes 13 to communicate the oil supply chamber 14 and the brake chamber 10. This slit 15 is formed into a substantially triangular shape as shown in FIG.
The opening area is configured to be controlled by the flange portion 9 of the housing 3 when the plunger 6 moves up and down.

A sheet material 16 having a center hole 17 is fixed to the inner periphery of the plunger 6 . Sheet material 16
The lower surface of the case 20 is provided with a compression coil spring 21.
is pressed, and the check ball 18 is pressed against the center hole 17 of the sheet material 16 by a compression coil spring 19 disposed inside the case 20. Further, the spring 21 presses the lifter body 5 against the cam 1a of the camshaft 1, and at the same time presses the plunger 6 against the push rod 22. Both ends of the push rod 22 have a spherical joint structure with connecting balls 23.
A rocker arm 24 is driven by the push rod 22, and the rocker arm 24 opens and closes an intake valve 25 (or exhaust valve) of the engine.

A hydraulic chamber 26 is formed inside the lifter body 5 and is separated from the oil supply chamber 14 by a sheet material 16 and a check ball 18. Further, a throttle hole 27 is formed in the lifter body 5, and the hydraulic chamber 26 and an escape groove 28 formed in the housing 3 communicate with each other through the throttle hole 27. Relief groove 2
Reference numeral 8 denotes an oil drain hole 29 formed in the housing 3, a check ball 30 for opening and closing the oil drain hole 29, and an oil outlet hole 32 in the cap material 31 to the outside, for example, to an oil chamber (not shown) of the cylinder block. It's communicating. In addition, check ball 30
is pressed to close the oil drain hole 29 by a compression coil spring 33, and the cap member 31 is screwed to the housing 3.

Further, an oil drain hole 35 is formed in the housing 3 so as to communicate with the brake chamber 10, and this oil drain hole 35 communicates with an oil outlet hole 38 of the cap member 37. A check ball 36 is installed in the oil drain hole 35.
The check ball 36 is pressed by a compression coil spring 39 so as to close the oil drain hole 35. Also, the cap material 37 is the housing 3
are screwed together.

The hydraulic valve lift device is provided in each cylinder of the internal combustion engine as shown in FIG. and,
The housing 3 is provided with an oil collecting pipe 40,
This collecting pipe 40 connects each valve lift device A ₁ , A ₂ ,
It communicates with oil outlet holes 38 that communicate with the brake chambers 10 of A ₃ and A ₄ . In FIG. 3, each of the valve lift devices A ₁ to A ₄ has the same structure, and the reference numerals for the valve lift devices A ₂ to _{A 3} are omitted. A relief valve 43 is provided in the communication pipe 40 via a conduit 42 . That is, the conduit 40 is connected to the check ball 45 and the cap material 47 (first
It communicates with the outside, for example, an oil chamber (not shown) of the cylinder block, through an oil drain hole 49 shown in the figure. The check ball 45 is pressed by a compression coil spring 46 to close the oil passage 42, and the cap member 47 is screwed to the body 48. Note that the opening pressure of the check ball 36 in the brake chamber 10 is set small, and the opening pressure of the relief valve 43 is set larger than that.

Next, the operation of the hydraulic valve lift device configured as described above will be explained. Before the cam 1a pushes up the lifter body 5, oil flowing from the oil supply port 11 flows into the oil supply groove 12, passes through the oil supply hole 13 of the plunger 6, and flows into the oil supply chamber 14. Further, the oil that has flowed into the oil supply chamber 14 flows into the brake chamber 10 through a variable throttle hole formed by the slit 15 and the flange portion 9. The oil in the oil supply chamber 14 pushes down the check ball 18 that closes the center hole 17 of the sheet material 16 and flows into the hydraulic chamber 26 of the lifter body 5. Refueling room 14,
The oil flowing into the hydraulic chamber 26 presses the plunger 6 and the lifter body 5 in opposite directions, that is, the lifter body 5 is pressed against the camshaft 1 side and the plunger 6 is pressed against the push rod 22 side. Also, the hydraulic chamber 26
The oil that has flowed into the tube flows out through the throttle hole 27, relief groove 28, and outlet hole 32.

The cam shaft 1 rotates and the cam 1a moves to the lifter body 5.
When the sheet material 16 starts to be pushed up, the oil pressure in the hydraulic chamber 26 increases, and the check ball 18 closes the center hole 17 of the sheet material 16. Therefore, the oil pressure in the hydraulic chamber 26 increases, pushing the plunger 6 up against the force of the spring 34 applied via the push rod 22, opening the intake valve 25 (or the exhaust valve). In this state, the oil in the hydraulic chamber 26 always gradually flows out into the relief groove 28 through the throttle hole 27, pushes the check ball 30, and flows out to the outside, and the volume of the hydraulic chamber 26 is reduced.

On the other hand, when the plunger 6 moves upward in FIG. 1 due to an increase in the oil pressure in the hydraulic chamber 26, the brake chamber 10
Oil flows into the oil supply chamber 14 through the slit 15. During this time, the oil that has flowed into the brake chamber 10 will cause the check ball 36 to move against the coil spring 36.
However, the relief valve 43 communicating with the outlet hole 38 and the collecting pipe 40 is closed by the check ball 45 pressed by the compression coil spring 46, and the oil does not flow out.

The oil in the hydraulic chamber 26 flows out through the throttle hole 27 and the volume of the hydraulic chamber 26 decreases, so the lift amount of the plunger 6 decreases. In other words, the lift amount of the plunger 6 is
6, the lift amount becomes small when the rotational speed of the camshaft 1 is slow, and approaches the cam profile of the camshaft 1 as the rotational speed increases. In this way, the hydraulic chamber 26
Since the volume of the valve 25, that is, the lift amount of the plunger 6 changes depending on the rotation speed of the camshaft 1, the seating timing of the valve 25 changes with respect to the rotation angle of the cam 1a.

If the engine speed is low, plunger 6
When the oil in the brake chamber 10 starts to fall, the volume of the brake chamber 10 decreases, so the oil in the slit 1
5. The oil flows into the oil supply chamber 14 through the oil supply hole 13.
When the plunger 6 further descends and the oil supply hole 13 is closed by the flange portion 9, the oil in the brake chamber 10 is squeezed by the slit 15, so the oil pressure in the brake chamber 10 increases, and there is a reaction force against the descent of the plunger 6. begins to act as A slit 15 communicates the brake chamber 10 and the oil supply chamber 14.
The opening area of the slit 15 is limited by the flange portion 9, and as the plunger 6 descends, the opening area of the slit 15 becomes smaller, the amount of oil escaping from the brake chamber 10 decreases, and the oil pressure in the brake chamber 10 increases.
The reaction force against the descent of the plunger 6 also increases.
Therefore, a sufficient braking force acts on the plunger 6 before the intake valve 25 (or the exhaust valve) closes, and the valve seating speed of the intake valve 25 can be reduced. Here, since the valve opening pressure of the check ball 36 is set as low as the supply oil pressure, the check ball 36 is pushed and the oil in the brake chamber 10 tries to flow out, but the check ball 36 is pushed and the oil in the brake chamber 10 tries to flow out. At the same time, the ball prevents the oil pressure from flowing into the brake chambers of other cylinders, and at the same time, the hydraulic pressure in the brake chamber 10 is reduced by the relief valve 43 due to the slow descending speed of the plunger 6.
Check ball 45 if the valve opening pressure does not rise above the set valve opening pressure.
I will not push you away.

As the rotational speed of the engine increases, the descending speed of the plunger 6 also increases proportionally. Brake chamber 1
Since the oil pressure at zero increases approximately in proportion to the square of the descending speed of the plunger 6, the oil pressure in the brake chamber 10 becomes extremely high and exceeds the set value of the relief valve 43. Therefore, the oil in the brake chamber 10 pushes open the check ball 36 and drains the oil from the outlet hole 3.
8. Push open the check ball 45 of the relief valve 43 through the collecting pipe 40 and conduit 41 to flow out to the outside to prevent the hydraulic pressure in the brake chamber 10 from becoming higher than the set value. In this way, it is possible to prevent the oil pressure in the brake chamber 10 from becoming extremely high and exerting too much braking force, causing an impact force on the push rod or the like, or preventing the valve seating timing from being abnormally delayed. As a result, a stable braking force can be applied equally to the intake and exhaust valves of each cylinder from low speed rotation to high speed rotation of the engine.

4 to 6 show a second embodiment, and the differences from the previous embodiment will be described.

As shown in FIGS. 4 and 5, conduits 42 and 55 are connected to the oil collecting pipe 40, the conduit 42 is provided with a relief valve 43 similar to that of the previous embodiment, and the conduit 55 is provided with an on-off valve 56. It is provided.

Further, as shown in FIGS. 4 and 6, the lifter bodies 5 of the valve lift devices A ₁ to A ₄ in each cylinder
The oil outlet hole 32 that communicates with the hydraulic chamber 26 inside is
It communicates with an oil collecting pipe 51 provided in the housing 3, and a conduit 53 having an on-off valve 54 is connected to this collecting pipe 51.

Next, the operation of the hydraulic valve lift device configured as described above will be explained.

When the on-off valve 54 communicating with the hydraulic chamber 26 is closed and the on-off valve 56 communicating with the brake chamber 10 is opened, when the camshaft 1 rotates and the cam 1a starts to push up the lifter body 5, the oil pressure in the hydraulic chamber 26 increases and the check is performed. The ball 18 is located in the center hole 1 of the sheet material 16.
Close 7. Since the on-off valve 54 is closed, the oil in the hydraulic chamber 26 does not flow out, and the plunger 6 is pushed up against the force of the spring 34 applied via the push rod 22 while keeping the volume of the hydraulic chamber 26 constant. In addition, since the on-off valve 56 leading to the brake chamber 10 is open, when the plunger 6 descends, the oil in the brake chamber 10 flows out through the check ball 36, the collecting pipe 40, and the on-off valve 56. The hydraulic pressure hardly increases, the hydraulic chamber brake hardly acts, and the plunger 6 operates according to the cam profile of the cam 1a. Therefore cam 1
It will be seated according to the seating buffer curve of a,
A delay in the seating timing of the valve 25 and a seating failure can be prevented.

Further, when the on-off valve 54 communicating with the hydraulic chamber 26 is opened and the on-off valve 56 communicating with the brake chamber 10 is closed, the valve lift amount can be made variable as in the first embodiment, and the valve is seated. Braking force can be applied at times. It goes without saying that the on-off valves 54 and 56 are selectively opened and closed.

Moreover, according to the present invention, the above-described operation of each hydraulic valve lift device provided in each cylinder of an internal combustion engine can be made uniform by controlling a hydraulic circuit common to each device.

[Brief explanation of the drawing]

Figures 1 to 3 show a first embodiment of the present invention, in which Figure 1 is an overall configuration diagram, Figure 2 is a partially enlarged view of the device, and Figure 3 is a hydraulic circuit system for a hydraulic brake. It is a diagram. Figures 4 to 6 show the second embodiment, where Figure 4 is an overall configuration diagram and Figure 5 is a diagram of the overall configuration.
The figure is a hydraulic circuit system diagram of a hydraulic brake, and FIG. 6 is a hydraulic circuit system diagram of a hydraulic chamber in a lifter body. A ₁ , A ₂ , A ₃ , A ₄ ... Hydraulic valve lift device main body, 1a ... Cam, 3 ... Housing, 5 ...
... Lifter body, 6 ... Plunger, 7 ... Flange part of plunger, 4, 8 ... Cylinder bore,
10...Brake room, 14...Refueling room, 15...
Slit, 25... Intake valve, 26... Hydraulic chamber, 30, 36... Check ball, 32... Hydraulic chamber oil outlet hole, 38... Brake chamber oil outlet hole, 40... Brake chamber oil collection pipe, 51 …
...Hydraulic chamber oil collecting pipe, 43...Relief valve, 54, 56...Opening/closing valve.

Claims (1)

[Scope of Claims] 1. A lifter body which is slidably inserted into the cylinder bore of the housing with one end in contact with the cam of the camshaft and has a hydraulic chamber inside; and a lifter body which is slidably inserted into the lifter body. and a plunger that is actuated by changes in oil pressure in the hydraulic chamber to transmit the movement of the cam to the intake and exhaust valves, the hydraulic chamber is equipped with means for releasing oil in the chamber, and the flange portion provided on the plunger and the cylinder bore are provided. This forms a brake chamber that holds oil that applies a braking force when the plunger descends, and a slit whose opening area decreases as the plunger descends. A hydraulic valve lift device is disposed in each cylinder of the internal combustion engine, and the brake chamber of each device is communicated with the brake chamber oil outlet hole through the check valve, and the oil flowing out from each check valve is connected to the brake chamber of the brake chamber. An internal combustion engine characterized in that an oil collecting pipe for collecting the oil is arranged in communication with oil outlet holes of each device, and the oil collecting pipe is equipped with a relief valve for controlling the oil pressure in the pipe to a set value or less. Hydraulic valve lift device. 2. A lifter body which is slidably inserted into the cylinder bore of the housing with one end abutting the cam of the cam and has a hydraulic chamber therein; a plunger that is actuated to transmit the movement of the cam to the intake and exhaust valves, the hydraulic chamber is equipped with means for releasing oil in the chamber, and a flange provided on the plunger and a cylinder bore provide a brake when the plunger is lowered. A hydraulic valve that forms a brake chamber that holds oil that applies force, and that communicates this brake chamber with the oil supply chamber of the plunger into which supplied oil flows through a slit whose opening area decreases as the plunger descends. A lift device is installed in each cylinder of the internal combustion engine; the brake chamber of each device is connected to the brake chamber oil outlet hole through a check valve, and an oil collecting pipe is connected to each cylinder to collect the oil flowing out from each check valve. This oil collecting pipe is installed in communication with the brake chamber oil outlet hole of the device, and a relief valve for controlling the oil pressure in the pipe to below a predetermined value and an on-off valve for appropriately discharging the oil in the pipe are installed in parallel. death,
An oil collecting pipe for collecting oil flowing out from the hydraulic chambers of each of the devices is arranged in communication with the hydraulic chamber oil outlet hole of each device, and an opening/closing valve is provided to appropriately discharge the oil in the pipe to the oil collecting pipe. A hydraulic valve lift device for an internal combustion engine, characterized in that: