JP2781034B2 - Variable valve device for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) A variable valve device for an engine according to the present invention is incorporated in a driving engine of an automobile, and the opening / closing state of the valve is changed according to the rotation speed of the engine. This allows the engine to operate with high efficiency.

(Prior Art) Except for some two-stroke engines, an engine used for driving a car is provided with an intake valve and an exhaust valve that pass through the inside and outside of a cylinder, and synchronizes both valves with the movement of a crankshaft. Open and close.

Conventionally, the intake valve and the exhaust valve of such an engine are usually always opened at a fixed phase and by a fixed amount regardless of the rotational speed of the crankshaft. Depending on the speed, it is not always possible to obtain the highest efficiency, the engine output cannot be obtained sufficiently, or the fuel consumption rate is poor, and more harmful components are contained in the combustion gas. There was a problem.

For this reason, for example, as disclosed in Japanese Patent Application Laid-Open No. 63-201306, by changing the opening / closing state of valves such as an intake valve and an exhaust valve according to the rotation speed of a crankshaft, etc. It has been considered that the air-fuel mixture is efficiently burned, or the combustion gas generated in the cylinder chamber is efficiently discharged.

The variable valve device for an engine disclosed in the above publication,
It is configured as shown in FIG.

In FIG. 4, 1 is a guide hole formed in the fixed portion 2 of the engine, 3 is a port opened on the inner peripheral surface of the guide hole 1, and 4 is a port connected to a hydraulic source 5 and an oil pan A switching valve 6, which selectively communicates with an oil reservoir such as an oil reservoir, has a bottomed cylindrical shape fitted slidably in the axial direction (up and down direction in FIG. 4) inside the guide hole 1. Tappet body, 7
The piston 8 is slidably fitted in the lower part of the tappet body 6 in the axial direction. The piston 8 is a push rod receiver mounted on the upper part of the inside of the tappet body 6.
A compression spring 10 provided between the push rod receiver 8 and the piston 7 is a hydraulic passage for communicating the port 3 with a lower space of the piston 7.

An outer peripheral surface of a cam 11 fixed to a crankshaft is in sliding contact with the lower surface of the tappet body 6, and a lower end portion of the push rod 12 is abutted on an upper surface of the push rod receiver 8. The push rod 12 is provided with downward elasticity by the elasticity of a return spring or the like attached to a valve opened and closed by the push rod 12, but this elasticity is sufficiently greater than the elasticity of the compression spring 9. It is big.

On the other hand, a switching valve 4 for selectively communicating the port 3 with a hydraulic source 5 and an oil reservoir such as an oil pan, and a hydraulic proportional control valve 13 provided between the hydraulic source 5 and the switching valve 4 are used for fuel injection. The pressure is switched in response to a signal from the controller 14 that issues a command according to conditions such as the amount, temperature, pressure, load condition, engine speed, etc., and pressure oil of a predetermined pressure is fed into the tappet body 6 through the port 3. Alternatively, the inside of the tappet body 6 is communicated with an oil reservoir such as an oil pan.

In the conventional variable valve device for an engine configured as described above, when the lift amount of the valve is increased (when the amount of movement in the opening direction of the valve is increased), the switching valve 4 is used.
To a state in which the port 3 and the hydraulic pressure source 5 communicate with each other,
Pressurized oil is fed into the tappet body 6 to raise the piston 7 against the elasticity of the compression spring 9, and the upper edge of the piston 7 abuts against the lower edge of the push rod receiver 8.

In this state, the piston 7 is located inside the tappet body 6.
When the tappet body 6 is pushed up with the rotation of the cam 11, the movement of the tappet body 6 is directly transferred to the push rod receiving portion. It is transmitted to the gold 8, pushes up the push rod 12, and opens the valve widely.

When the lift amount of the valve is reduced, the switching valve 4 is switched to a state in which the port 3 communicates with the oil reservoir, so that the oil in the tappet body 6 can be discharged to the oil reservoir.

In this state, even if the tappet main body 6 is pushed up with the rotation of the cam 11, the push rod receiver 8 descends against the tappet main body 6 against the elasticity of the compression spring 9, so that the tappet main body 6 Movement of the push rod receiver 8
Not immediately transmitted. Since the push rod receiver 8 starts to rise after the upper edge of the piston 7 abuts against the lower edge of the push rod receiver 8, the upper edge of the piston 7 contacts the lower edge of the push rod receiver 8. The amount by which the valve is lifted is reduced by the amount by which the tappet body 6 is pushed up before it abuts.

(Problems to be Solved by the Invention) However, in the case of a conventional variable valve device for an engine configured and operated as described above, the following inconvenience occurs.

That is, in the case of the above-mentioned conventional device, a pipe having a switching valve 4 and a hydraulic proportional control valve 13 in the middle thereof is provided continuously with the port 3 for supplying and discharging pressure oil into the tappet body 6. It is inevitable that a relatively large amount of oil present in the oil will adversely affect the valve opening characteristics of the valve. In particular, when air is mixed into the oil, the amount of compression increases, and the above-mentioned adverse effects become significant.

The variable valve device for an engine according to the present invention solves the above-mentioned disadvantages.

(Means for Solving the Problems) A variable valve device for an engine according to the present invention comprises: a guide hole formed in a fixed portion of an engine; a first port opened on an inner peripheral surface of the guide hole; A switching valve for selectively communicating a port with an oil reservoir and a hydraulic pressure source, and an inner peripheral surface of the guide hole, which is opened at a position off the first port,
A second port communicating with the hydraulic pressure source, a cylindrical member slidably fitted axially inside the guide hole,
A piston member fitted slidably in the axial direction inside one half of the cylindrical member and having a hydraulic chamber therein; a valve seat member fixedly provided inside a middle portion of the cylindrical member; An on-off valve configured to control communication between the hydraulic chamber and a first hydraulic passage communicating with the second port, and a valve body of the on-off valve being biased in a closing direction. A pressing rod fitted inside the valve seat member slidably in the axial direction and having one end facing the valve element of the on-off valve;
A second piston fitted to the other half of the cylindrical member, one side of which is opposed to the other end of the pressing rod; and the other side of the pilot piston communicates with the first port. A hydraulic passage, a first cam portion fixed to an intermediate portion of a camshaft that rotates in synchronization with rotation of the crankshaft of the engine, and an outer peripheral surface of which is slidably contactable with one end surface of the cylindrical member; A second cam portion fixed to an intermediate portion of the camshaft and having an outer peripheral surface slidably contacting one end surface of the piston member, and a transmission member for transmitting movement of the other end of the cylindrical member to a valve. It is composed of

(Action) In the case of the variable valve device for an engine of the present invention configured as described above, the operation of the switching valve allows the first port to communicate with the oil reservoir or the hydraulic port,
The open / close state of the valve can be changed.

That is, when the first port is communicated with the oil reservoir based on the operation of the switching valve, the hydraulic pressure does not act on the other surface side of the pilot piston, and the on-off valve is closed by the force of the spring.

As a result, the pressure oil is kept sealed in the hydraulic chamber provided inside the piston member, so that the piston member is prevented from sliding with respect to the cylindrical member, and one end surface of the piston member is prevented. The movement of the second cam portion having its outer peripheral surface slidably contacted is transmitted to a valve via a piston member, pressurized oil sealed in a hydraulic chamber, a cylindrical member, and a transmission member. The second cam portion moves according to the outer peripheral surface shape.

Further, when the first port is communicated with a hydraulic pressure source based on the operation of the switching valve, hydraulic pressure acts on the other surface of the pilot piston, and the pilot piston causes the valve body of the on-off valve to move through the pressing rod. Push to open this on-off valve.

When the on-off valve opens, the hydraulic chamber provided inside the piston member communicates with the hydraulic source via the first hydraulic passage and the second port. As the hydraulic source, for example, an oil pump or the like built into the engine is used, and since only relatively low pressure oil is sent from this hydraulic source, the piston member is slidable with respect to the cylindrical member. It becomes a state.

As a result, even when the movement of the second cam portion is transmitted to the piston member, the movement of the piston member is not transmitted to the cylindrical member, and is based on the sliding contact with the outer peripheral surface of the first cam portion. Only the movement of the cylindrical member is transmitted to the valve via the transmission member.

In the case of the variable valve device for an engine of the present invention that operates as described above, when the valve is opened and closed, the oil that receives pressure in accordance with the movement of the second cam portion is only the oil sealed in the hydraulic chamber. For this reason, even when a strong pressure is applied, the amount by which this oil is compressed is so small that it does not pose a practical problem, and the operation of the valve device becomes stable.

(Example) Next, the present invention will be described in more detail while describing the illustrated example.

1 to 3 show an embodiment of the present invention. FIG. 1 is a cross-sectional view showing the overall structure, and FIG. 2 shows the relationship between a cylindrical member and a piston member, as viewed from below FIG. FIG. 3 is a diagram showing the relationship between the first cam portion and the second cam portion as viewed from the right side of FIG.

A first port 15 and a second port 16 are provided on the inner peripheral surface of the guide hole 1 formed in the fixed portion 2 of the engine so as to be shifted in the axial direction (vertical direction in FIG. 1).

Among them, a switching valve 18 is provided in the middle of a pipe 17 having one end connected to the first port 15, and the first port 15 is selectively used as an oil reservoir 19 and a discharge port of an oil pump 20 which is a hydraulic pressure source. Communication is possible. The other end of the pipe 21 having one end connected to the second port 16 communicates with the discharge port of the oil pump 20.

The cylindrical member 22 is slidably fitted in the axial direction inside the guide hole 1 having the first and second ports 15 and 16 opened in the inner peripheral surface as described above. .

One half (the lower half in FIG. 1) of this cylindrical member 22 includes
A bottomed cylindrical piston member 23 is slidably fitted in the axial direction. The interior of the piston member 23 is a hydraulic chamber
The opening / closing state of the valve can be changed by controlling the communication between the hydraulic chamber 24 and the outside by an on-off valve 25 described below.

In this way, the on-off valve 25 for changing the open / close state of the valve is
A valve seat member 26 is screwed and fixed inside the intermediate portion of the cylindrical member 22, and a steel ball 27, which is a valve body, is opposed to a lower end opening edge of the valve seat member 26. This steel ball
A compression spring 28 is provided between the lower surface of the
And presses the steel ball 27 toward the edge of the lower end opening. Therefore, the on-off valve 25 remains closed unless an external force is applied, and the pressure oil is kept sealed in the hydraulic chamber 24.

On the other hand, a pressing rod 29 is fitted inside the valve seat member 26 so as to be slidable in the axial direction. One end (the lower end in FIG. 1) of the pressing rod 29 is opposed to a steel ball 27 constituting the on-off valve 25 so that the on-off valve 25 is opened as the pressing rod 29 descends. I have.

The other end (the upper end in FIG. 1) of the pressing rod 29 is made to protrude from the end surface of the valve seat member 26 so that the cylindrical member 22
Abuts on one surface (the lower surface in FIG. 1) of the pilot piston 30 fitted to the other end of the pilot piston.

The other surface side (the upper surface side in FIG. 1) of the pilot piston 30 and the first port 15 are formed with a concave groove 31 formed on the upper outer peripheral surface of the cylindrical member 22 and one end of the concave groove 31. The inner surface of the cylindrical member 22 at the other end is communicated with the inner surface of the cylindrical member 22 through a second hydraulic passage 33 formed of a through hole 32 that is opened, and the pressure oil can be sent to the other surface. .

In addition, the second port 16 and the pressure oil chamber 24 have a concave groove 34 formed on the outer peripheral surface of the intermediate portion of the cylindrical member 22, one end on the inner surface of the concave groove 34, and the other end. On the inner peripheral surface of the cylindrical member 22, through holes 35 respectively opened, and through holes 36 formed in the valve seat member 26 in a state of being connected to the other end of the through holes 35,
The first hydraulic passage 42 including the center hole 37 of the valve seat member 26 communicates with the first hydraulic passage 42.

On the other hand, first cam portions 38 and 38 and a second cam portion 39 as shown in FIG. 3 are fixedly provided at an intermediate portion of the cam shaft 43 which rotates in synchronization with the rotation of the crankshaft of the engine. Have been.

Of these, the outer peripheral surfaces of the first cam portions 38, 38 formed at an interval from each other are freely slidable on one end surface (lower end surface in FIG. 1) of the cylindrical member 22, respectively. At times, the cylindrical member 22 may be fitted to the outer peripheral shape of the first cam portions 38, 38.
Are displaced in the axial direction.

Also, the first cam portion is provided at an intermediate portion of the camshaft.
A second cam portion 39 is fixed to a portion sandwiched between 38 and 38. The outer peripheral surface of the second cam portion 39 is brought into sliding contact with one end surface (the lower end surface in FIG. 1) of the piston member 23, and the piston member 23 is rotated in accordance with the outer peripheral shape of the second cam portion 39. It is made to displace in the direction.

Further, a lid attached to the other end opening of the cylindrical member 22
At the center of the outer surface of 40, a push rod 41 as a transmission member
, And the movement of the cylindrical member 22 can be freely transmitted to a valve such as an intake valve or an exhaust valve.

In the case of the engine variable valve device of the present invention configured as described above, the first port 15 is operated by operating the switching valve 18.
The open / close state of the valve can be changed by communicating the oil with the oil reservoir 19 or with the discharge port of the oil pump 20 as a hydraulic pressure source.

For example, when the engine is rotating at high speed, based on a command from a controller (not shown), the switching valve 18
The state is switched to the state shown in FIG. 1, and the first port 15 communicates with the oil reservoir 19.

As a result, the hydraulic pressure does not act on the other surface side of the pilot piston 30, and the pilot piston 30 does not press the pressing rod 29, so that the end of the pressing rod 29 faces the steel ball 27.
Is pressed against the valve seat member 26 by the elastic force of the compression spring 28, and the on-off valve 25 is held in a closed state.

As a result, the hydraulic chamber provided inside the piston member 23
The pressurized oil remains sealed in the inside 24, and the piston member 23 and the cylindrical member 22 are in a state where they are integrally connected. That is, in this state, the piston member 23 is prevented from sliding with respect to the cylindrical member 22, and the second cam portion having its outer peripheral surface slidably contacting one end surface of the piston member 23
The movement of 39 is transmitted to the valve via the piston member 23, the pressure oil sealed in the hydraulic chamber 24, the cylindrical member 22, the lid 40, and the push rod 41, and the valve is adapted for high-speed rotation. The second cam portion 39 moves according to the shape of the outer peripheral surface. That is, in this case, the lift amount of the valve increases, and each valve opens greatly.

Note that even if the pressure oil sealed in the hydraulic chamber 24 leaks, the hydraulic chamber 24 has a stroke in which the valve moves to the closed state (the cylindrical member 22 and the piston member 23 move downward in FIG. 1). Pressure oil is newly supplied through the first hydraulic passage 42 composed of the concave groove 34 and the through hole 36 at the end of the stroke of the hydraulic chamber 24. There will be sufficient pressure oil present.

That is, the engine variable valve device of the present invention also functions as a lash adjuster that always automatically performs proper tappet adjustment.

When the engine is rotating at a low speed, the switching valve 18 is also controlled based on a signal from a controller (not shown).
Is switched to the state opposite to that shown in FIG. 1, and the first port 15 is communicated with the discharge port of the oil pump 20, which is a hydraulic pressure source.

As a result, the pressurized oil flows from the first port 15 to the concave groove 31 and the through hole.
The pilot piston 30 is fed to the other surface side of the pilot piston 30 through a second hydraulic passage 33 constituted by 32 and the pilot piston 30 is pressed downward in FIG. When the pilot piston 30 is pressed downward, a steel ball 27, which is the valve element of the on-off valve 25, is pressed downward in FIG. Ball 27 is valve seat member 26
, The on-off valve 25 is opened.

When the on-off valve 25 is opened in this manner, the hydraulic chamber 24 provided inside the piston member 23 has a concave groove 34 and a through hole 35,
Through a first hydraulic passage 42 composed of 36 and a central hole 37, and a second port 16, it communicates with the discharge port of the oil pump 20 that is a hydraulic pressure source. The oil pump 20, which is a hydraulic pressure source, only receives relatively low pressure oil. In this state, the hydraulic pressure in the hydraulic chamber 24 increases the approach force between the second cam portion 39 and the push rod 41. (The force for narrowing the interval between the two members 39 and 41). Therefore, the piston member 23 is slidable with respect to the cylindrical member 22.

As a result, even when the movement of the second cam portion 39 is transmitted to the piston member 23, the piston member 23
, And the movement of the piston member 23 is not transmitted to the cylindrical member 22.

Along with this, the outer peripheral surfaces of the first cam portions 38, 38 and the end surface of the cylindrical member 22 come into sliding contact with each other, and both members 38, 22
Only the movement of the cylindrical member 22 based on the sliding contact is transmitted to the valve via the lid 40 and the push rod 41, which are transmission members.

The first cam portions 38, 38 are in contact with each other for the first time after the second cam portion 39 has pushed the piston member 23 to some extent inside the cylindrical member 22, so that the first cam portions 38, 38 The lift amount becomes small, and good combustion conditions can be obtained even when the engine is rotating at low speed.

In the case of the engine variable valve device of the present invention that operates as described above, when the valve is opened and closed, the second cam portion 39 is used.
The oil that receives pressure in accordance with the movement of the oil is only the oil sealed in the hydraulic chamber 24, so even if it is subjected to strong pressure, the amount of oil that is compressed is small enough to cause no practical problem. Also, the operation of the valve device becomes stable.

(Effect of the Invention) Since the variable valve device for an engine according to the present invention is configured and operates as described above, the amount of oil compression for switching the operation of the valve is suppressed to a very small amount, and the adverse effect due to the oil compression is suppressed. Can be almost eliminated, and the operation of the valve can be stabilized.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a cross-sectional view showing the overall structure, and FIG. 2 shows the relationship between a cylindrical member and a piston member, as viewed from below FIG. FIG. 3, FIG. 3 is a view showing the relationship between the first cam portion and the second cam portion, as viewed from the right side of FIG. 1, and FIG. 4 is a partial cross section showing a conventional variable valve device for an engine. FIG. 1: Guide hole, 2: Fixing member, 3: Port, 4: Switching valve, 5: Hydraulic source, 6: Tappet body, 7: Piston, 8: Push rod receiver, 9: Compression spring, 10: Hydraulic passage, 11: cam, 12: push rod, 13: hydraulic proportional control valve, 14: controller, 15: first port, 16: second port, 17: pipe, 18: switching valve, 19: oil reservoir,
20: oil pump, 21: pipe, 22: cylindrical member, 23: piston member, 24: hydraulic chamber, 25: open / close valve, 26: valve seat member, 27: steel ball,
28: compression spring, 29: pressing rod, 30: pilot piston, 31:
Groove, 32: Through hole, 33: Second hydraulic passage, 34: Groove, 35, 36:
Through hole, 37: center hole, 38: first cam portion, 39: second cam portion, 40: lid, 41: push rod, 42: first hydraulic passage, 43: cam shaft.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-54-49413 (JP, A) JP-A-59-182609 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F01L 13/00 301

Claims (1)

(57) [Claims] 1. A guide hole formed in a fixed portion of an engine, a first port opened on an inner peripheral surface of the guide hole,
A switching valve that selectively communicates the first port with the oil reservoir and the hydraulic pressure source, and a second valve that opens at a position outside the first port on the inner peripheral surface of the guide hole and communicates with the hydraulic pressure source. And a cylindrical member fitted slidably in the axial direction inside the guide hole, and slidably fitted in the axial direction inside one half of the cylindrical member. A piston member having a hydraulic chamber therein, a valve seat member fixedly provided inside the intermediate portion of the cylindrical member, and a valve body opposed to the valve seat member. An on-off valve for controlling communication with a first hydraulic passage communicating therewith, a spring for urging a valve body of the on-off valve in a closing direction, and a slidably fitted axially inside the valve seat member. A pressing rod having one end opposed to the valve element of the on-off valve, and fitted on the other end of the cylindrical member, with one surface facing upward. A pilot piston opposed to the other end of the pressing rod; a second hydraulic passage for communicating the other surface of the pilot piston with the first port; and a rotation in synchronization with rotation of a crankshaft of the engine. A first cam portion fixed to an intermediate portion of the camshaft and having an outer peripheral surface slidably contacting one end surface of the cylindrical member; and a first cam portion similarly fixed to an intermediate portion of the camshaft and an outer peripheral surface of the piston member. An engine variable valve device comprising: a second cam portion slidably contacting one end surface; and a transmission member for transmitting movement of the other end of the cylindrical member to a valve.