JPH05163916A - Valve mechanism - Google Patents

Abstract

(57) [Summary] [Objective] The object of the present invention is to improve the fuel consumption rate at low speed running by setting the intake / exhaust efficiency corresponding to the operating state of the engine, and to output at high speed under high load operation. It is to obtain a valve mechanism having a structure capable of obtaining an increase. According to the present invention, a first oil passage 5 for supplying oil to a space between a bottom surface of a lash adjuster 3 provided on a cylinder head and the cylinder head is provided.
The 2nd which constitutes the drain which drains oil from this space
Oil passage 6, a check valve 7 arranged at the connecting portion between the first oil passage 5 and the mounting portion and allowing the flow of oil to the bottom side, and the first and second oil passages 5, 6 To the rocker arm 2 by setting the open / closed position of each of the first and second on-off valves 8 and 9. It is characterized in that the position of the rocker arm 2 and the valve opening / closing cam 10 is changed by changing the position of the lash adjuster 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve mechanism, and more particularly to a variable valve lift mechanism.

[0002]

As is well known, in a valve mechanism used for an automobile engine, one end of a rocker arm is used as a fulcrum, and the other end is pressurized by a valve opening / closing cam to slide a valve stem. There is a structure that opens and closes the valve. Then, at one end of the rocker arm in the above-described valve mechanism, a lash adjuster that doubles as a fulcrum and automatically adjusts the valve clearance is provided. The structure of the lash adjuster described above is, for example, the structure shown in FIG. That is, the lash adjuster A shown in FIG. 4 includes an adjuster body B fixed in a cylinder head and a slidable plunger having an oil chamber formed therein, which is inserted into the adjuster body B. C, a spring D that abuts the bottom surface of the plunger C and urges the plunger C in a direction to project from the inside of the adjuster body B, the adjuster body B in which the spring D is located, and the plunger C. And a check valve E arranged in an oil passage provided between the oil chamber and the oil chamber and having a habit of allowing only the oil to flow toward the bottom surface of the plunger C. The lash adjuster A has a habit of lowering the plunger C when the rocker arm G moves in the direction of opening the valve by the cam F due to the oil filled in the adjuster body B and the plunger C. Is blocked by shutting off the oil passage with the check valve E, the rocker am G with the plunger C as a fulcrum can be swung, and the valve is opened. When the base circle of the cam F corresponds to the valve stem and the valve is closed, the plunger C is pushed up by the spring D, so that the oil in the plunger C opens the check valve E and flows out to the outside. Along with this, the plunger C is swung, so that the other end of the rocker arm G is brought into contact with the head portion of the valve stem to eliminate the valve clearance.

[0003]

However, in the above-mentioned valve mechanism, although the valve clearance can be automatically adjusted, the maximum opening amount of the valve corresponds to the maximum lift amount from the cam profile. In addition, since this amount is always constant, it is not possible to set the intake / exhaust efficiency according to the engine speed and the load from the accelerator opening. In other words, the cam profile described above, for example, in the case of an engine that requires high speed rotation,
Since it is set in consideration of increasing the intake rate of the air-fuel mixture and the exhaust efficiency, the fuel consumption rate at low speed rotation tends to be sacrificed. On the contrary to the above case, when the cam profile is set in consideration of the fuel consumption rate, there is a possibility that the output at the time of high speed rotation or high load operation may not be sufficiently obtained.

Therefore, in view of the above-mentioned problems in the conventional valve mechanism, an object of the present invention is to improve the fuel consumption rate at low speed and to increase the high speed by setting intake and exhaust efficiencies corresponding to the operating state of the engine. It is to obtain a valve mechanism having a structure capable of increasing output during high load operation.

[0005]

In order to achieve this object, the present invention is a valve mechanism including a lash adjuster arranged at a rocking fulcrum position of a rocker arm, the bottom surface of the lash adjuster and a cylinder. A first oil passage connected to the space between the head and supplying the oil to the space, a second oil passage for draining the oil from the space, the first oil passage, and the mounting portion. A check valve which is arranged at a connection portion with the bottom surface side and allows a flow of oil to the bottom surface side; and first and second opening / closing valves which are respectively arranged in the first and second oil passages. By setting the open / closed states of the first and second opening / closing valves,
It is characterized in that the position of the lash adjuster with respect to the rocker arm is changed to change the facing position of the rocker arm and the valve opening / closing cam.

The present invention is also characterized in that the lash adjuster is slidable by the cylinder head.

Further, according to the present invention, when the first opening / closing valve is closed and the second opening / closing valve is opened, the position where the lash adjuster faces the rocker arm is lowered according to the opening amount, and the rocker arm is moved. The valve lift obtained by the contact between the valve opening and closing cam and the valve opening and closing cam is made small.

According to the present invention, when the first opening / closing valve is opened and the second opening / closing valve is closed, the position where the lash adjuster faces the rocker arm is raised in accordance with the opening amount of the rocker arm and the valve. It is characterized in that the valve lift obtained by contact with the opening / closing cam is set to a large state.

[0009]

According to the present invention, the position of the lash adjuster due to the sliding displacement can be changed by setting the opening amounts of the first and second opening / closing valves.

Further, according to the present invention, by setting the opening of the first or second opening / closing valve, the facing position between the lash adjuster and the rocker arm is changed to change the facing relationship between the rocker arm and the valve opening / closing cam. The valve lift can be changed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic sectional view for explaining the structure of a valve mechanism according to an embodiment of the present invention. The valve mechanism 1 shown in FIG. 1 is characterized by having a structure for sliding a lash adjuster on a cylinder head.

In FIG. 1, the valve mechanism 1 is equipped with a lash adjuster 3 arranged at the end corresponding to the rocking fulcrum of the rocker arm 2. The lash adjuster 3 is slidably mounted on the cylinder head. Has been.

On the other hand, in the cylinder head, in addition to the oil passage 4 for supplying oil to the lash adjuster 3 which is usually provided, there is provided an opening between the bottom surface of the adjuster body of the lash adjuster 3 and the cylinder head. The oil passage 5 and the second oil passage 6 are provided. Therefore, on the bottom surface side of the adjuster body of the lash adjuster 3 in the cylinder head, a space portion is formed for storing oil when oil flows in. The first oil passage 5 is an oil supply oil passage branched from the oil passage 4 and connected to a space between the bottom surface of the adjuster body of the lash adjuster 3 and the cylinder head.
A check valve 7 that allows only the flow of oil toward the bottom surface side of the lash adjuster 3 is arranged at this connection portion. The second oil passage 6 serves as a drain for collecting the oil accumulated in the space between the bottom surface of the adjuster body of the lash adjuster 3 and the cylinder head.

In each oil passage, there are provided, for example, first and second opening / closing valves 8 and 9 which are electromagnetic valves, and these opening / closing valves 8 and 9 are opened / closed by a control unit (not shown). It is supposed to be done. The first and second on-off valves 8 and 9 change the contact position between the lash adjuster 3 and the rocker arm 2 by setting oil supply / discharge to the first and second oil passages 5 and 6. Therefore, the control unit closes the first opening / closing valve 8 and opens the second opening / closing valve 9 in the first position, and opens the first opening / closing valve 8 in the second position. The on-off valve 9 is closed and the second position is switched to be selected.

In the first position among the above-mentioned respective positions of the on-off valve, the flow of oil in each oil passage is set to the state shown in FIG. In this position, the second oil passage 6 is opened so that the oil accumulated in the space between the bottom surface side of the lash adjuster 3 and the cylinder head can be discharged. Therefore, the lash adjuster 3 can descend, and when descending, the position of the rocking fulcrum of the rocker arm 2 is set to the lowest position.
Is not in contact with the valve opening / closing cam 10, a so-called valve resting state, or a minimum swing amount with respect to the cam profile, in other words, an interval at which the smallest valve lift is obtained, is defined as the valve opening / closing cam 10. Is set during the period. Also, in this position, for example,
If the interval at which the smallest valve lift is obtained is set between the valve opening / closing cam 10 and the valve opening / closing cam 10, the operating angle for rocking the rocker arm 2 with respect to the rotation angle of the valve opening / closing cam 10 becomes small. The rocking time of the rocker arm 2 obtained when the maximum diameter portion of the valve opening / closing cam 10 and the rocker arm 2 correspond to each other within the angle range is reduced. In the first position, the contact state between the rocker arm 2 and the valve opening / closing cam 10, specifically,
It goes without saying that the non-contact state and the state in which the interval at which the minimum swing amount is obtained is set are appropriately selected depending on the design conditions. Further, when the first position is set, it is necessary that the rocker arm 2 is also swingably displaced in accordance with the displacement of the lash adjuster 3, and further, when the lash adjuster 3 descends. It is necessary to avoid the risk of the 2 falling off. Therefore, a connecting member 11 such as a clip member is provided at a position where the lash adjuster 3 side and the rocker arm 2 side face each other, and the connecting member 11 is provided at a position where the rocker arm 2 and the valve stem face each other. Is also provided.

On the other hand, in the second position among the positions of each on-off valve, the oil flow in each oil passage is set to the state shown in FIG. In this position, the oil from the first oil passage 7 is supplied through the check valve 6 to collect and fill the space between the bottom surface of the adjuster body of the lash adjuster 3 and the cylinder head. The pressure of that part rises as it goes. Therefore, the lash adjuster 3 is pushed up. For example, when the push-up amount is the largest, the rocking fulcrum of the rocker arm 2 is located at the highest position, and when the valve opening / closing cam 10 rotates, the rocker arm 3 moves. The second cam follower is brought into contact with the base circle in the cam profile. In other words,
The operating angle for rocking the rocker arm 2 with respect to the rotation angle of the valve opening / closing cam 10 is increased, and the contact between the peripheral portion of the valve opening / closing cam 10 and the rocker arm 2 is within that angle range. A state in which the contact time becomes long is set, and swinging on the rocker arm 2 side obtained until reaching the maximum diameter portion of the valve opening / closing cam 10 and from this position to the base circle within this contact time It is designed to lengthen the time. Therefore, when the push-up amount of the lash adjuster 3 is maximized, the maximum rocking amount of the rocker arm 2 is obtained according to the cam profile, and the valve lift is also set to the maximum amount. Will be done. In this position, since the lash adjuster 3 is pushed up with the maximum amount of protrusion, the adjuster body is positioned at the position of the cylinder head facing the upper end of the adjuster body by hitting. The stopper 12 is provided. Further, the positioning when the lash adjuster 3 is pushed up is not limited to using the stopper described above, and for example, instead of the stopper 12, a stroke corresponding to the maximum pushing up amount of the lash adjuster 3 is determined, This stroke may be performed by adjusting the opening / closing of the first and second opening / closing valves 8 and 9,
Specifically, when the amount by which the lash adjuster 3 is pushed up by opening the first on-off valve 8 corresponds to the stroke described above, the first and second on-off valves 8 and 9 are closed and the lash adjuster 3 is placed at that position. You may make it hold | maintain.

The positions of the on-off valves described above are selectively set according to the rotational speed information and the load information based on the accelerator opening which are input to the control unit, and the plunger 3B in the set positions is set. The amount of oil supply and the amount of oil discharge that set the displacement amount are set at the same time.

Since this embodiment has the above-mentioned structure,
In the control unit to which the engine speed information and the load information are respectively input, the position of each on-off valve is selected in order to set the valve lift amount according to each information. That is, the first position is set for each on-off valve when the engine is rotating at a low speed or at a low load operation.
In the first position, as described with reference to FIG. 2, the position of the lash adjuster 3 facing the rocker arm 2, that is, the position of the rocking fulcrum of the rocker arm 2 is the lowest, and the valve opening / closing is performed. The position where the rocker arm 2 is most distant from the working cam 10, and the rocking amount of the rocker arm 2 obtained when the valve opening / closing cam 10 is rotated cannot be obtained or is the smallest. The operation is performed in a state where the intake amount of the air-fuel mixture is reduced in the state where the valve lift is the smallest.

On the other hand, when the engine is rotating at high speed or under high load, the second position is set for each on-off valve. In the second position, as described with reference to FIG. 3, the position of the lash adjuster 3 facing the rocker arm 2, that is, the position of the rocking fulcrum of the rocker arm 2 is the highest and the valve opening / closing cam is the highest. An operation in which the rocker arm 2 is brought into contact with the base circle of 10 to maximize the valve lift, thereby maximizing the intake amount and exhaust efficiency of the air-fuel mixture. Is done.

Even when the position of each on-off valve is set, since the lash adjuster 3 itself is lifted, it is of course possible to adjust the valve clearance like a normal lash adjuster. There is.

According to the above-described embodiment, for example, in the first position with respect to each opening / closing valve, the contact between the rocker arm 2 and the valve opening / closing cam 10 is released, and the so-called valve is stopped. In this case, for example, in a DOHC type engine, it is possible to switch to the SOHC type, so the valve opening / closing cam and rocker arm due to the pressure from the return spring on the valve side are reduced by the number of driven valves. The contact pressure between the two can be eliminated, and the friction resistance generated during this can be reduced. Therefore, it is possible to improve the low speed torque by reducing the torque spent for driving the cam shaft during the low speed rotation. In this case, the valve operating angle for the rotation of the valve opening / closing cam can be controlled by setting the lift amount of the valve in the non-rest state and the displacement position of the lash adjuster. It is possible to secure the required torque at low speed even if the number of is small, and further to improve the torque at low speed.

Further, according to this embodiment, for example, DOH
In the C type, if one cam profile is set for high speed and high load, and the other cam profile is set for low speed and low load, it is possible to use different cams, for example, by the low speed and low load cams. In the case of valve drive, improve fuel efficiency and, at high speed and high load, drive the valve with a cam that has a cam profile set for this purpose, so that the required engine output can be easily obtained. You can

Further, according to the present embodiment, when the cams having different profiles are used as described above, the position of the lash adjuster is simply slid and displaced in the cylinder head, so that it is provided in, for example, the rocker arm. Compared to the structure in which the valve lift is changed by inserting and removing the built-in piston with respect to the rocker arm corresponding to each cam for high-speed performance and low-speed performance, the parts that generate mechanical shock and It is possible to eliminate the need for a mechanical connecting part, and it is unlikely that the positioning accuracy will change or the operation that cannot be performed due to dust mixed in the insertion / removal part will not occur. This is advantageous in terms of the service life of the drive unit, including maintaining the positioning accuracy of the unit.

Although the positions of the on-off valves in FIGS. 2 and 3 described above are described in the most extreme cases only when the engine is running at low speed and high speed, the positions are set at these positions. By controlling the opening / closing amount of the on-off valve together, it is of course possible to obtain the valve lift according to the entire operation range including the above-described setting of the minimum lift and the maximum lift.

[0026]

As described above, according to the present invention, the structure of the lash adjuster provided for adjusting the valve clearance can be changed with respect to the lash adjuster in the normally used valve mechanism. The valve lift can be changed according to the operating state of the engine. Therefore, it is possible to optimize the intake / exhaust efficiency in each operation range, which easily reduces the fuel consumption at low speed rotation and low load, and easily obtains the required output at high speed rotation and high load. Will be able to.

Further, according to the present invention, the above-mentioned effect can be easily obtained by a simple structure in which a hydraulic circuit is attached to the inside of the cylinder head for a normally used lash adjuster.

[Brief description of drawings]

FIG. 1 is a schematic sectional view for explaining a configuration of a valve mechanism according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining an example of operating states of the valve mechanism shown in FIG.

FIG. 3 is a schematic diagram for explaining another example of the operating state of the valve mechanism shown in FIG.

FIG. 4 is a schematic sectional view for explaining a conventional structure of a lash adjuster used for a valve mechanism.

[Explanation of symbols]

 1 valve mechanism 2 rocker arm 3 lash adjuster 5 first oil supply oil passage 6 second oil supply oil passage 7 check valve 8 first opening / closing valve 9 second opening / closing valve

Claims (4)

[Claims] 1. A valve mechanism comprising a lash adjuster arranged at a rocking fulcrum position of a rocker arm, wherein the valve mechanism is connected to a space between a bottom surface of the lash adjuster and a cylinder head, and oil is provided in this space. Supply first
Of the oil passage, a second oil passage for draining oil from the space, and a connection portion between the first oil passage and the mounting portion, and allows the oil flow to the bottom surface side. A check valve and first and second opening / closing valves respectively arranged in the first and second oil passages are provided, and the opening and closing states of the first and second opening / closing valves are set. By so doing, the position of the lash adjuster with respect to the rocker arm is changed to change the facing position of the rocker arm and the valve opening / closing cam. 2. The valve mechanism according to claim 1, wherein the lash adjuster is provided slidably on the cylinder head. 3. The valve mechanism according to claim 1, wherein the lash adjuster faces the rocker arm according to the opening amount when the first opening / closing valve is closed and the second opening / closing valve is opened. A valve mechanism that lowers the position to reduce the valve lift obtained by contact between the rocker arm and the valve opening / closing cam. 4. The valve mechanism according to claim 1, wherein the lash adjuster has a position facing the rocker arm according to the opening amount when the first opening / closing valve is opened and the second opening / closing valve is closed. A valve mechanism that is raised to increase the valve lift obtained by the contact between the rocker arm and the valve opening / closing cam.