JP2563796Y2 - Hydraulic valve gear for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic valve device for an internal combustion engine, and more particularly to a device for adjusting the timing of closing a valve such as an exhaust valve.

[0002]

2. Description of the Related Art A typical prior art is shown in FIG. The cam 1 is rotationally driven by the crankshaft of the two-stroke diesel engine, whereby the oil column in the passage 4 is moved by the follower 2 and the plunger 3 fixed thereto, so that the exhaust valve 6 of the diesel engine 5 Is lowered against the spring force of the air pressure supplied to the space 9 from the air. Hydraulic oil from a hydraulic source 10 is supplied to a chamber 12 on the head side of a sleeve 11 that accommodates the plunger 3. An oil drain passage 13 connected to the tank is connected to the sleeve 11, and a variable throttle 14 is interposed in the oil drain passage 13. FIG. 5 shows a state in which the exhaust valve 6 is closed. At this time, the follower 2 and the plunger 3 are in the lowered position. A passage 16 is formed in the plunger 3 and communicates from the room 12 to a small-diameter space 17. Sleeve 1
1 is connected to an oil discharge passage 13 at a relief port 15.

When the cam 1 reaches the maximum lift as shown in FIG. 6, the escape port 15 opens into the space 17, so that
In order to compensate for the sudden decrease in the oil pressure for maintaining the valve-open state of the exhaust valve 6 against the spring force of the air pressure in the chamber 9, the profile of the cam 1, that is, the cam surface, Extra push-in margin is provided. The closing timing of the valve body of the exhaust valve 6 is controlled by the variable throttle 14 from the relief port 15.
By adjusting the flow rate, the reduction of the hydraulic force and the balance of the spring force by the compressed air in the room 9 are determined. Therefore, the prior art shown in FIGS. 5 and 6 has a problem that the accuracy of the timing setting at the time of closing the valve is low in the high-speed internal combustion engine.

In this prior art, the hydraulic oil from the relief port 15 is returned to the tank through the oil drain passage 13, so that the pump power of the hydraulic power source 10 is wasted.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to set the timing of closing a hydraulic valve such as an exhaust valve of an internal combustion engine with high accuracy and to prevent loss of power. It is an object of the present invention to provide a hydraulic valve train for an internal combustion engine that is made possible.

[0006]

According to the present invention, a spring force is applied to a valve body of a valve of an internal combustion engine in a direction in which the valve closes, and the valve body is displaced and opened by the oil column against the spring force. In a hydraulic valve operating device for an internal combustion engine, a cam rotatably driven by a crankshaft of the internal combustion engine, a first plunger driven by the cam and having a recess formed along an axial direction, and slidably fitted in the recess. A second plunger having a convex portion that fits therein, the second plunger having a passage communicating the space between the first and second plungers and the space in the concave portion, and the first and second plungers. And a second plunger for driving the oil column, the sleeve having a first plunger along the axial direction.
A first communication hole is formed near the plunger, and a second communication hole is formed near the second plunger. The first communication hole communicates with the gap when the lift of the cam is small, and when the lift is large, Closed by the first plunger,
The second communication hole is closed by the second plunger when the lift is small, communicates with the gap when the lift is large, a hydraulic source, and a first passage for guiding hydraulic oil from the hydraulic source,
A check valve interposed in the first passage and guiding hydraulic oil from a hydraulic pressure source to the first communication hole, a second passage connected to the second communication hole,
A solenoid valve interposed in the second passage, which opens and closes, a discharge passage for discharging hydraulic oil from the solenoid valve, and means for controlling opening and closing of the solenoid valve to adjust the timing of closing the valve of the internal combustion engine. And a hydraulic valve train for an internal combustion engine.

The present invention also provides a pressure accumulator connected to a discharge passage, another check valve interposed in the first passage and guiding hydraulic oil from a hydraulic source, a discharge passage, and the two check valves. And a third passage connecting the first passage between the valves.

[0008]

[0009]

[0010]

According to the present invention, the cam driven by the crankshaft of the internal combustion engine drives the first plunger, and the projection of the second plunger is slidably fitted in the recess of the first plunger. When the cam lift is small,
Hydraulic oil from a hydraulic source is supplied from the first communication hole to the gaps of the first and second plungers via the first passage and the check valve, and the gap is increased. When the lift of the cam increases in this state, the oil column is driven by the second plunger in a direction to open the valve element of the valve of the internal combustion engine. At this time, the solenoid valve is kept closed. In this way, in the valve opening stroke, the working space is filled with the hydraulic oil, and the oil column moves while keeping the interval between the first and second plungers long, and the valve opening state is maintained as described above.

By opening the solenoid valve before the lift of the cam becomes small and enters the descending stroke, the hydraulic oil in the gap is discharged from the second communication hole through the second passage and the solenoid valve through the discharge passage, Accordingly, the second plunger is displaced toward the first plunger and descends, so that the valve of the internal combustion engine starts to close. Then, when the lift of the cam becomes small and the cam enters the descending stroke, the gap between the first and second plungers descends in a state shorter than the initial state, and thus the second plunger opens earlier by that much. Reach to previous position and return. Thus, the timing of closing the valve of the internal combustion engine can be advanced.

[0012]

[0013]

Further, according to the present invention, power loss can be prevented by accumulating hydraulic oil from the solenoid valve in the accumulator.

[0015]

FIG. 1 is an overall system diagram of an embodiment of the present invention. 2 or 4 cycle diesel engine 2
0 is provided with an exhaust valve 21, and a valve element 22 of the exhaust valve 21 can be seated on a valve seat 23, and an exhaust passage 24 is provided.
From the combustion exhaust gas. Exhaust valve 21
A piston 26 is fixed to a valve rod 25 formed integrally with the valve body 22 of this embodiment. The piston 26 is housed in a cylinder 27, and compressed air is supplied to a cylinder chamber 28. Is applied to the valve seat 23 in the direction in which it is seated. A hydraulic piston 29 is also fixed to the valve stem 25, and a pressure tube 31 forming an oil column is connected to a chamber 30 on the head side. A cam 33 is fixed to the crankshaft 32 of the diesel engine 20, and the cam 33 is driven to rotate. A roller 34, which is a follower, is in sliding contact with the cam surface of the cam 33.
A first plunger 36 is formed on the rod 35 to which the. In connection with the first plunger 36, a second plunger 37 is provided above the first plunger 36. These first
The second plungers 36 and 37 are housed in a sleeve 38. The spring 39 applies a spring force so that the roller 34 contacts the cam surface of the cam 33. Second plunger 37
The chamber 40 on the head side of the sleeve 38 facing the
1 and thus the second plunger 37 drives the oil column of the pressure tube 31.

FIG. 2 is a diagram for explaining the operation of FIG. FIG. 2A shows a lift diagram of the cam 33, and FIG.
(2) shows the open / closed state of the solenoid valve 53, and FIG. 2 (3) shows the open / closed state of the exhaust valve 21. In the second passage 52, a throttle 62 is provided between the second communication hole 47 and the electromagnetic valve 53, and suppresses a sudden change in the pressure of the hydraulic oil in the gap 43.

FIG. 3 shows the first and second plungers 36,
It is an expanded sectional view near 37. A recess 41 is formed in the first plunger 36 along the vertical axis of FIGS. 1 and 3. The second plunger 37 is provided in the recess 4
1 has a convex portion 42 slidably fitted thereto. This convex part 4
In 2, a passage 45 is formed that communicates a space 43 between the first and second plungers 36 and 37 and a space 44 in the recess 41. The enlarged portion 42a at the end of the convex portion 42 abuts on a flange-like portion 36b protruding inward in the radial direction of the first plunger 36, whereby the first and second plungers 36,
Maximum length L1 of gap 43 between 37 is regulated.

The sleeve 38 has a first
A first communication hole 46 is formed near the plunger 36, and a second communication hole 47 is formed near the second plunger 37. Before the first communication hole 46 at time t1 in FIG.
When the lift of the cam 33 is small as shown in (1), the cam 33 communicates with the gap 43 as shown in FIG.
When the lift is large as at times t2 to t3 in FIG.
It is closed by the first plunger 36 as shown in (2) and FIG. 3 (3). The second communication hole 47 is closed by the second plunger 37 when the lift of the cam 33 is small, and communicates with the gap 43 when the lift of the cam 33 is large.
The axial position of the sleeve 38 is determined.

Referring again to FIG. 1, hydraulic oil from a hydraulic source 48, which is a hydraulic pump, is guided from a first check valve 50 to a first communication hole 46 through a first passage 49. First check valve 5
The second check valve 51 is interposed on the upstream side of 0, that is, on the hydraulic pressure source 48 side.

A second passage 52 is connected to the second communication hole 47, and a two-position spring offset type solenoid valve 53 that opens and closes is interposed in the second passage 52. Solenoid valve 53
Is discharged through a discharge passage 54, and a pressure accumulator 55 is connected to the discharge passage 54. Accumulator 55
Presses the piston 57 by the spring 56 to accumulate the operating oil in the discharge passage 54. A third passage 5 is provided between the discharge passage 54 and the two check valves 50 and 51 of the first passage 49.
8 is connected.

The rotation angle of the crankshaft 32 of the diesel engine is detected by a rotation angle detecting means 59, and its output is given to a processing circuit 60 such as a microcomputer.
Thus, the switching operation of the solenoid valve 53 is controlled.

In operation, at time t1 in FIG. 2, the first plunger 36, and hence its upper surface 36a,
When the roller 34 is at the lower limit position A as shown in (1), that is, when the roller 34 is on the base circle 33a of the cam surface of the cam 33 as shown in FIG.
Opens into a gap 43, into which the hydraulic oil is supplied from a hydraulic pressure source 48 via a first passage 49 and first and second check valves 50, 51 to fill the space, so that the second plunger 37 is at a maximum. It is separated by a length L1 upward in FIG. In this state, the valve body 22 of the exhaust valve 21 causes the valve seat 2 to move by the spring force of the compressed air in the piston chamber 28.
3 and is in a valve closed state as shown in FIG.

In the valve opening stroke, at time t2 in FIG.
As shown in (2), the protrusion 33b on the cam surface of the cam 33
Is the roller 34 and thus the first plunger 36 in FIG.
When the hydraulic oil is pushed upward as shown in (2), the hydraulic oil in the gap 43 remains closed because the solenoid valve 53 remains closed.
The first and second plungers 36 and 37 are united to push the oil column in the pressure pipe 31 into the chamber 30 while the air gap 43 is kept in the maximum length L1 while being kept trapped in the sleeve 38. Put in.

Before reaching the maximum lift, the first communication hole 46
Is closed by the peripheral surface of the first plunger 36, and the second
The second communication hole 47 closed by the peripheral surface of the plunger 37 is, as clearly shown in FIG.
Open at 3. In this state, since the solenoid valve 53 is closed as described above, the gap 43 remains at the maximum length L1.

At the beginning of the valve closing stroke, at time t3 in FIG.
As shown in FIG. 4 (3), before the lift of the cam 33 enters the descending stroke which becomes smaller at time t3a in FIG. 2 (1), as shown in FIGS. 2 (2) and 3 (3). When the solenoid valve 53 is switched and opened, the cam 33 is as shown in FIG. 4C, the hydraulic oil in the gap 43 is discharged from the second communication hole 47 to the second passage 52, and the second plunger 37 is The discharged hydraulic oil is displaced downward in FIG. 3 (3) and descends. As a result, the valve body 22 is moved into the cylinder chamber 28.
As a result of the action of the spring force of the compressed air, the valve rises to start closing the valve.

As the second plunger 37 descends, the second
The communication hole 47 is closed by the peripheral surface of the second plunger 37 to be in the state shown in FIG. 3D, and at time t3a in FIG. 2, the lift of the cam 33 is reduced as shown in FIG. , The distance L2 of the gap 43 is reduced by ΔL (= L1−L2) by the amount of the hydraulic oil discharged from the gap 43, and the first and second plungers 36, 3
7 descends together. At this time, the hydraulic oil discharged from the second communication hole 47 is stored in the pressure accumulator 55 because the first communication hole 46 is closed by the peripheral surface of the first plunger 36.

In the latter half of the valve closing stroke, before the lift of the cam 33 is minimized, that is, before the descending stroke is finished, the top portion 37a of the second plunger 37
The position B of the second plunger 37 in FIG.
3 (5), whereby the valve body 22 of the exhaust valve 21 is seated on the valve seat 23 and closed.
In this way, the first plunger 36 descends and the cam 33
Before reaching the lower limit position A, the exhaust valve 21 is closed, and thus the valve closing timing can be advanced.

Immediately before the upper surface 37a of the second plunger 37 reaches the position B, the position of the first communication hole 46 is selected so that the first communication hole 46 opens into the gap 43, and thereby the accumulator 55 is opened. The hydraulic oil stored in the first plunger 37 flows from the discharge passage 54 through the third passage 58 and the first check valve 50 into the space 43 through the first communication hole 46, whereby the second plunger 37 is moved to the position shown in FIG. ) Is pushed up with respect to the first plunger 36. This can prevent the oil column in the pressure pipe 31 from becoming negative pressure.

In the state of FIG. 3 (5) showing the valve closed state, at time t4 in FIG. 2, the roller 34 exists on the base circle 33a of the cam 33 as shown in FIG.
Is separated by the maximum length L1 and the gap 43 is filled with hydraulic oil, the upper surface 36b of the first plunger 36 is at the position A,
The upper surface 37a of the second plunger 37 is located at positions A and B shown in FIG. In this state, the solenoid valve 53 is switched and closed.

In the embodiments shown in FIGS. 1 to 4, the accumulator 55 and the third passage 58 may be omitted, and the hydraulic oil from the solenoid valve 53 may be returned to the tank of the hydraulic power source 48 via the discharge passage 54.

[0031]

[0032]

The present invention can be implemented in connection with not only diesel engines but also other internal combustion engines, and can be implemented in connection with intake valves and other valves as well as exhaust valves.

[0034]

As described above, according to the present invention, the closing timing of the valve of the internal combustion engine can be directly controlled by controlling the opening and closing of the solenoid valve. , The timing of closing the valve can be achieved with high accuracy. Further, since the timing of closing such a valve can be controlled during operation of the internal combustion engine,
It is also possible to improve the operating performance of the internal combustion engine.

Further, according to the present invention, the hydraulic oil discharged through the solenoid valve can be collected in the pressure accumulator, returned to the first passage and recycled for use, thereby preventing power loss. it can.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment shown in FIG. 1;

FIG. 3 is a sectional view showing an operation state of first and second plungers 36 and 37.

FIG. 4 is a front view showing a rotation state of a cam 33.

FIG. 5 is a diagram showing a prior art.

FIG. 6 is a diagram showing another operation of the prior art shown in FIG. 5;

DESCRIPTION OF SYMBOLS 20 Diesel engine 21 Exhaust valve 22 Valve element 26 Piston 28 Cylinder chamber 29 Hydraulic piston 31 Pressure pipe 32 Crankshaft 33 Cam 34 Roller 35 Rod 36 First plunger 37 Second plunger 38 Sleeve 39 Spring 39 Spring 40 Head side Space 41 Concave part 42 Convex part 43 Air gap 44 Space 45 Passage 46 First communication hole 47 Second communication hole 48 Hydraulic power source 49 First passage 50 First check valve 51 Second check valve 52 Second passage 53 Electromagnetic valve 54 Discharge Passage 55 Accumulator 58 Third passage 62 Throttle

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-233116 (JP, A) JP-A-4-292506 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] 1. A hydraulic valve operating apparatus for an internal combustion engine, wherein a spring force acts on a valve body of a valve of the internal combustion engine in a direction in which the valve closes, and the valve body is displaced and opened by the oil column against the spring force. A cam rotatably driven by a crankshaft of the internal combustion engine; a first plunger driven by the cam and having a recess formed along the axial direction; and a second plunger having a protrusion slidably fitted in the recess. A plunger, comprising: a second plunger in which a passage communicating with a space between the first and second plungers, a space in the concave portion is formed; and a sleeve that houses the first and second plungers. The oil column is driven by two plungers, and a first communication hole is formed in the sleeve near the first plunger and a second communication hole is formed near the second plunger in the axial direction. The through hole communicates with the gap when the lift of the cam is small, and is closed by the first plunger when the lift is large. The second communication hole is closed by the second plunger when the lift is small. Is larger, a hydraulic pressure source, a first passage for guiding hydraulic oil from the hydraulic source, and a check valve interposed in the first passage for guiding hydraulic oil from the hydraulic source to the first communication hole. A second passage connected to the second communication hole, a solenoid valve interposed in the second passage and opening and closing, a discharge passage for discharging hydraulic oil from the solenoid valve, and closing a valve of the internal combustion engine Means for controlling the opening and closing of the solenoid valve to adjust the timing of the hydraulic valve actuation for the internal combustion engine. 2. An accumulator connected to a discharge passage, another check valve interposed in the first passage upstream of the check oil from the check valve, and guiding the check oil from a hydraulic pressure source; The hydraulic valve train for an internal combustion engine according to claim 1, further comprising a third passage connecting the discharge passage and a first passage between the two check valves.