JPH03182612A - Variable valve device for engine - Google Patents

Abstract

PURPOSE:To dissolve adverse effect based on the compression of oil on a valve opening characteristic almost completely by closing the oil pressure chamber of a piston member brought into sliding contact with a second cam part on the basis of the operation of a change over valve. CONSTITUTION:At the time of communicating a first port 15 with an oil sump 19 on the basis of the operation of a change over valve 18, oil pressure does not act upon the other face side of a pilot piston 30, so that a switching valve 25 is closed by the force of a compression spring 28. As a result, pressure oil remains sealed in an oil pressure chamber 24 provided inside a piston member 23 by a steel ball 27, and the piston member 23 is hindered from sliding against a cylindrical member 22. The movement of a second cam part 39 whose peripheral surface is in sliding contact with one end face of the piston member 23 is transmitted to the valve through the piston member 23, oil pressure sealed in the oil pressure chamber 24, the cylindrical member 22 and a push rod 41. Accordingly, adverse effect based on the compression of oil can be dissolved almost completely, and the action of the valve is therefore stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The variable valve device for an engine according to the present invention is incorporated into a driving engine of an automobile, and by changing the opening/closing state of the valve according to the rotational speed of the engine, etc. This allows the engine to operate with high efficiency.

(Prior art) Some engines used for driving automobiles, etc.
Except for cycle engines, engines are equipped with an intake valve and an exhaust valve that allow communication between the inside and outside of the cylinder, and both valves are opened and closed in synchronization with the movement of the crankshaft.

Conventionally, the intake and exhaust valves of such engines were usually always opened at a constant phase and by a constant amount, regardless of the rotational speed of the crankshaft, etc.
Depending on the rotational speed of the crankshaft, it may not always be possible to obtain the highest efficiency, resulting in insufficient engine output, poor fuel consumption, or even
There were problems such as an increase in harmful components contained in the combustion gas.

For this reason, as disclosed in Japanese Patent Application Laid-open No. 63-201306, for example, by changing the opening/closing status of intake valves, exhaust valves, etc. according to the rotational speed of the crankshaft, etc., it is possible to It has been considered to ensure that the air-fuel mixture is efficiently combusted, or that the combustion gas generated within the cylinder chamber is efficiently discharged.

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

In FIG. 4, 1 is a guide hole formed in a fixed part 2 of the engine, 3 is a port opened on the inner circumferential surface of this guide hole 1, and 4 is a port 3 connected to a hydraulic source 5 and an oil pan. The switching valve 6 selectively communicates with the oil reservoir, etc., is a bottomed cylindrical valve fitted inside the guide hole 1 so as to be slidable in the axial direction (vertical direction in FIG. 4). tappet body, 7
8 is a piston fitted to the inner lower part of the tappet main body 6 so as to be slidable in the axial direction; 8 is a bushing rod support mounted to the inner upper part of the tappet main body 6; 9 is a bushing rod holder;
A compression spring 10 provided between the bushing rod holder 8 and the piston 7 is a hydraulic passage for communicating the port 3 and the space below the piston 7.

The outer peripheral surface of a cam 11 fixed to the crankshaft is in sliding contact with the lower surface of the tappet body 6, and the lower end of the bushing rod 12 is abutted against the upper surface of the bushing rod receiver 8.

The bushing rod 12 is given downward elasticity by the elasticity of a return spring attached to the valve opened and closed by the bushing rod 12, but this elasticity is sufficiently larger than the elasticity of the compression spring 9. It becomes.

On the other hand, there is a switching valve 4 that selectively communicates the port 3 with the hydraulic source 5 and an oil reservoir such as an oil pan, and between the hydraulic source 5 and the switching valve 4.
The hydraulic proportional control valve 13 provided between is a controller that issues commands according to conditions such as fuel injection amount, temperature, pressure, load conditions, and engine rotation speed. It is switched in response to a signal from port 4 to send pressurized oil at a predetermined pressure into tappet body 5 through port 3, or to communicate the inside of tappet body 6 to an oil reservoir such as an oil pan.

In the conventional engine variable valve device configured as described above, when increasing the lift amount of the valve (when increasing the amount of movement of the valve in the opening direction), the switching valve 4 is connected to the port 3. Pressurized oil is fed into the tappet body 6, the piston 7 is raised against the elasticity of the compression spring 9, and the upper end edge of the piston 7 is connected to the bushing rod holder 8. Hit the bottom edge.

In this state, the lower space below the piston 7 inside the tappet body 6 is filled with pressure oil, so when the tappet body 6 is pushed up as the cam 11 rotates, , this movement of the tappet body 6 is directly transmitted to the bushing rod holder 8, and the movement of the bushing rod 12
Push up to open the valve wide.

In addition, when reducing the lift amount of the valve, selector valve 4
is switched to a state where the port 3 and the oil reservoir are communicated with each other, so that the oil in the tappet body 6 can be freely discharged to the oil reservoir.

In this state, even if the tappet body 6 is pushed up with the rotation of the cam 11, the bushing rod holder 8 descends against the tappet body 6 against the elasticity of the compression spring 9. The movement is to Butschrod receiver 8,
The bushing rod holder 8 starts to rise, which is not immediately transmitted, after the upper edge of the piston 7 hits the lower edge of the bushing rod holder 8. The lift amount of the valve decreases by the amount that the tappet body 6 is pushed up until it hits the edge.

(Problems to be Solved by the Invention) However, in the case of the conventional engine variable valve device configured and operated as described above, the following disadvantages occur.

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

The variable valve device for an engine of the present invention eliminates the above-mentioned disadvantages.

(Means for Solving the Problems) The variable valve device for an engine of the present invention includes a guide hole formed in a fixed part of the engine, a first port opened on the inner peripheral surface of the guide hole, and a first port opened on the inner circumferential surface of the guide hole. a switching valve that selectively communicates the port with the oil reservoir and the hydraulic source; a second port that opens at a position away from the first port on the inner peripheral surface of the guide hole and communicates with the hydraulic source; Inside the guide hole above,
a cylindrical member fitted so as to be slidable in the axial direction; a piston member fitted inside one half of the cylindrical member to be slidable in the axial direction and having a hydraulic chamber therein; Consists of a valve seat member fixedly installed inside the intermediate portion of the cylindrical member and a valve body facing the valve seat member, and controls communication between the hydraulic chamber and the first hydraulic passage leading to the second port. a spring that biases the valve body of the on-off valve in the closing direction; and a spring that is fitted inside the valve seat member so as to be slidable in the axial direction, with one end facing the valve body of the on-off valve. a pressing rod, a pilot piston fitted into the other end of the cylindrical member and having one side facing the other end of the pressing rod, and the other side of the pilot piston being connected to the first port. communicate,
It is fixed to the middle part of the second hydraulic passage and the camshaft that rotates in synchronization with the rotation of the engine crankshaft.
a first cam portion whose outer peripheral surface is slidably in contact with one end surface of the cylindrical member; and a second cam portion which is also fixed to the intermediate portion of the camshaft and whose outer peripheral surface is slidably in contact with one end surface of the piston member. and a transmission member for transmitting the movement of the other end of the cylindrical member to the valve.

(Function) In the case of the engine variable valve device of the present invention configured as described above, the operation of the switching valve determines whether the first port is communicated with the oil reservoir or with the hydraulic pressure source. , it is possible to change the open/closed state of the valve.

That is, when the first port is brought into communication with the oil reservoir based on the operation of the switching valve, no hydraulic pressure acts on the other surface of the pilot piston, and the on-off valve is closed by the force of the spring.

As a result, the pressure oil remains sealed in the hydraulic chamber provided inside the piston member, and the piston member is prevented from sliding with respect to the cylindrical member, and one end surface of the piston member is prevented from sliding against the cylindrical member. The movement of the second cam portion, the outer peripheral surface of which is in sliding contact with the second cam portion, is transmitted to the valve via the piston member, pressure oil sealed in the hydraulic chamber, the cylindrical member, and the transmission member,
This valve moves according to the shape of the outer peripheral surface of the second cam portion.

Furthermore, when the first port is connected to a hydraulic pressure source based on the operation of the switching valve, hydraulic pressure acts on the other side of the pilot piston, and this pilot piston presses the valve body of the on-off valve via the pressing rod. Press to open this on-off valve.

When the on-off valve opens, the hydraulic chamber provided inside the piston member is opened via the first hydraulic passage and the second port.
Connects to hydraulic power source. The hydraulic source used is, for example, an oil pump built into the engine, and only relatively low-pressure oil is sent from this hydraulic source, so the piston member can slide freely against the cylindrical member. It becomes a state.

As a result, even if the movement of the second cam part is transmitted to the piston member, the movement of this piston member will not be transmitted to the cylindrical member, and the movement of the piston member will not be transmitted to the cylindrical member. Only the movement of the cylindrical member is transmitted to the valve via the transmission member.

In the case of the engine variable valve device of the present invention, which operates as described above, when opening and closing the valve, the second cam portion !
Since the only oil that receives pressure according to the pressure is the oil sealed in the hydraulic chamber, even if it is subjected to strong pressure, the amount of oil compressed is small enough to cause no practical problems, and the valve The operation of the device also becomes stable.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view showing the overall configuration, and FIG. 2 is a view from below of FIG. 1 showing the relationship between the cylindrical member and the piston member. FIG. 3 is a view seen from the right side of FIG. 1, showing the relationship between the first cam part and the second cam part.

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

A switching valve 18 is provided in the middle of the pipe 17, one end of which is connected to the first port 15, to select the first port 15 as the oil reservoir 19 and the discharge port of the oil pump 20, which is the hydraulic pressure source. We are able to communicate freely. Also, the second port 16
The other end of the pipe 21 has one end connected to the oil pump 2.
It communicates with the discharge port 0.

A cylindrical member 22 is placed inside the guide hole l in which the first and second ports 15 and 16 as described above are opened on the inner peripheral surface.
The fitting device is slidable in the axial direction.

A bottomed cylindrical piston member 23 is fitted into one half of the cylindrical member 22 (lower half in Figure 's1) so as to be slidable in the axial direction. The interior of this piston member 23 is a hydraulic chamber 24, and by controlling the communication between this hydraulic chamber 24 and the outside by an on-off valve 25 that is delayed, the opening/closing state of the valve can be changed.

The on-off valve 25 for changing the open/closed state of the valve in this way is
It is composed of a valve seat member 26 screwed and fixed to the inside of the intermediate portion of the cylindrical member 22, and a steel ball 27, which is a valve body, facing the lower end edge of the valve seat member 26. Between the lower surface of the steel ball 27 and the back surface of the hydraulic chamber 24,
A compression spring 28 is provided to press the steel ball 27 against the lower end edge. For this reason, the on-off valve 25 remains closed unless an external force is applied, and the hydraulic pressure chamber 24 is maintained in a sealed state.

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

The other end of the pressing rod 29 (the upper end in FIG. 1) projects from the end surface of the valve seat member 26 and is connected to a pilot piston 30 fitted to the other end of the cylindrical member 22. It is pressed against one side (the bottom side in Figure 1).

The other surface side of the pilot piston 30 (the upper surface side in FIG. 1) and the first port 15 are connected to a groove 31 formed on the upper outer circumferential surface of the cylindrical member 22, and one end connected to the groove 31.
The inner surface of the cylindrical member 22 is connected to the inner surface of the cylindrical member 22 by a second hydraulic passage 33, which is composed of a through hole 32 whose other end is opened to the inner circumferential surface of the cylindrical member 22, so that pressure oil can be freely sent to the other surface side. There is.

The second port 16 and the hydraulic chamber 24 are connected to a concave groove 34 formed on the outer peripheral surface of the intermediate portion of the cylindrical member 22, and have one end on the inner surface of the concave groove 34 and the other end on the inner surface of the concave groove 34. shaped member 22
a through hole 35 opened in the inner peripheral surface of the valve seat member 26, a through hole 36 formed in the valve seat member 26 in a continuous state with the other end of the through hole 35, and a center hole 37 of the valve seat member 26. They are communicated by a first hydraulic passage 42 consisting of.

On the other hand, a first cam part 38, 38 and a second cam part 39 as shown in FIG. has been done.

Among these, the outer circumferential surfaces of the first cam portions 38 and 38, which are formed at intervals, can be slidably contacted with one end surface (lower end surface in FIG. 1) of the cylindrical member 22, respectively. In some cases, the cylindrical member 22 is axially displaced to match the outer circumferential shape of the first cam portion 38,38.

Further, the first cam portion 3 is located at the intermediate portion of the camshaft.
A second cam portion 39 is fixed to the portion sandwiched by 8.38. The outer circumferential surface of the second cam portion 39 is brought into sliding contact with one end surface of the piston member 23 (the lower end surface in FIG. It is designed to be displaced in the direction.

Further, one end of a bushing rod 41, which is a transmission member, is abutted against the center of the outer surface of the lid 40, which is attached to the other end opening C of the cylindrical member 22, so that the movement of the cylindrical member 22 is controlled by the intake valve or can be freely transmitted to valves such as exhaust valves.

In the case of the engine variable valve device of the present invention configured as described above, by operating the switching valve 18, the first port 1
The open/close state of the valve can be changed by communicating the valve 5 with the oil reservoir 19 or with the discharge port of the oil pump 20, which is a hydraulic pressure source.

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

As a result, no hydraulic pressure acts on the other side of the pilot piston 30, and the pilot piston 30 no longer pushes the pressing rod 29, so the steel ball 27, which the end of the pressing rod 29 faces, is pressed against the compression spring. Due to the elasticity of 28, the valve seat member 26
The on-off valve 25 is kept closed.

As a result, the pressure oil remains sealed in the hydraulic chamber 24 provided inside the piston member 23, and the piston member 23 and the cylindrical member 22 become as if they were integrally connected. . That is, in this state, the piston member 2
3 is prevented from sliding with respect to the cylindrical member 22, and the movement of the second cam portion 39 whose outer peripheral surface is in sliding contact with one end surface of the piston member 23 is prevented from sliding against the piston member 23 and the hydraulic chamber 24. Pressure oil sealed inside, the cylindrical member 22, and the lid 40.
The information is transmitted to the valve via the bushing rod 41, and this valve moves in accordance with the outer peripheral surface shape C of the second cam portion 39 for high-speed rotation (that is, in this case, The lift amount of the valve increases, and each valve opens wide.

In addition, even if the pressure oil sealed in the hydraulic chamber 24 leaks, the valve will move to the closed state (the cylindrical member 22 and the piston member 23 descend in FIG. 1). At the end of the stroke), new pressure oil is supplied through the first hydraulic passage 42 consisting of the groove 34 and the through hole 36, so when the valve is opened next time, the inside of the hydraulic chamber 24 is There will be sufficient pressure oil.

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

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

As a result, pressure oil is sent from the first port 15 to the other side of the pilot piston 30 via the second hydraulic passage 33 constituted by the groove 31 and the through hole 32. is pressed downward in FIG. Based on the downward pressure of the pilot piston 30, the steel ball 27, which is the valve body of the on-off valve 25, is
Pushed downward in FIG. 1 against the elasticity of the compression spring 28, the steel ball 27 is separated from the valve seat member 26, and 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 opens into the first hydraulic passage 4 consisting of the groove 34, the through hole 35, 36, and the center hole 37.
2. It communicates with the discharge port of the oil pump 20, which is a hydraulic pressure source, through the second port 16. The oil pump 20, which is a hydraulic pressure source, only receives relatively low-pressure oil, and in this state, the hydraulic pressure in the hydraulic chamber 24 is caused by the approaching force ( Both members 39.
For this reason, the piston member 23 is in a slidable state with respect to the cylindrical member 22.

As a result, the movement of the second cam portion 39 is caused by the movement of the piston member 23.
Even if the piston member 23 is transmitted to
The movement will not be transmitted to the cylindrical member 22.

Along with this, the outer circumferential surface of the first cam portion 38.38 and the end surface of the cylindrical member 22 come into sliding contact, and both members 3
8. Only the movement of the cylindrical member 22 based on the sliding contact in 22 is
It comes to be transmitted to the valve via the lid body 4o and the bushing rod 41, which are transmission members.

The first cam part 38.38 comes into sliding contact only after the second cam part 39 pushes the piston member 23 to the inside of the cylindrical member 22. The amount of lift is reduced, making it possible to obtain good combustion conditions even when the engine is rotating at low speeds.

In the case of the engine variable valve device of the present invention that operates as described above, when opening and closing the valve, the second cam portion 39
The only oil that is subjected to pressure depending on the movement is the oil sealed in the hydraulic chamber 24, so even if it is subjected to strong pressure, the amount of compressed oil is small enough to not cause any practical problems. , the operation of the valve device also becomes stable.

(Effects of the Invention) The variable valve device for engines of the present invention is constructed and operates as described above, so that the amount of oil compression required for switching the valve operation by 4 degrees is kept to a minimum, and the amount of oil compression is reduced to a minimum. It is possible to almost eliminate the negative effects caused by this, making it possible to stabilize the operation of the valve.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view showing the overall configuration, and FIG. 2 is a view from below of FIG. 1 showing the relationship between the cylindrical member and the piston member. Figure 3 is a view from the right side of Figure 1 showing the relationship between the first cam part and the second cam part, and Figure 4 is a partial cross-section showing a conventional variable valve device for engines. It is a diagram. 1: Guide hole, 2: Fixed part, 3: Port, 4: Switching valve, 5: Hydraulic source, 6: Tappet body, 7: Piston, 8:
push rod holder, 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 sump, 20
oil pump, 21: pipe, 22: cylindrical member, 23:
Piston member, 24: Hydraulic chamber, 25: Open/close valve, 28: $
Seat member, 27: Steel ball, 28: Compression spring, 29: Pressing rod,
30: Pilot piston, 31: Concave groove, 32: Through hole,
33: Second hydraulic passage, 34: Concave groove, 35.36: Through hole, 37: Center hole, 38: First cam part, 39: Second cam part, 40: Lid body, 41: Push rod , 42: first hydraulic passage, 43: camshaft.

Claims (1)

[Claims] (1) A guide hole formed in a fixed part of the engine, a first port opened on the inner peripheral surface of this guide hole, and a switching valve that selectively communicates this first port with an oil reservoir and a hydraulic source. and a second port that opens on the inner circumferential surface of the guide hole at a position away from the first port and communicates with the hydraulic source, and is slidably fitted in the guide hole in the axial direction. a cylindrical member mounted thereon; a piston member fitted inside one half of the cylindrical member so as to be slidable in the axial direction and having a hydraulic chamber therein; Consisting of a fixedly installed valve seat member and a valve body facing the valve seat member,
An on-off valve that controls communication between the hydraulic chamber and the first hydraulic passage leading to the second port, a spring that biases the valve body of the on-off valve in the closing direction, and a shaft inside the valve seat member. a pressing rod that is fitted so as to be slidable in any direction and has one end facing the valve body of the on-off valve, and the other end of the cylindrical member;
A pilot piston with one side facing the other end of the pressing rod, a second hydraulic passage communicating the other side of the pilot piston with the first port, and a second hydraulic passage synchronized with the rotation of the engine crankshaft. A first cam part is fixed to the middle part of the camshaft which rotates, and has an outer circumferential surface slidably in contact with one end face of the cylindrical member; A variable valve device for an engine, comprising a second cam portion slidably contacted with one end surface of a piston member, and a transmission member for transmitting movement of the other end portion of the cylindrical member to the valve.