JP2011157843A - Solenoid valve used for valve operating characteristic changing device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve responsiveness by preventing a delay when performing a change and control, in a valve operating characteristic changing device changing the valve operating characteristic of an engine by controlling a dual oil supply passage by a solenoid valve. <P>SOLUTION: The rocker arm 6 of the engine is attached with a lash adjuster 10 adjusting a valve clearance by opening/closing a ball check valve 102, and the first oil supply passage 21 and second oil supply passage 22 are respectively connected to the lower side and upper side of a needle piston 103. The solenoid valve 24 placed on a communication portion for both the supply passages is formed with an upper opening 24U, a lower opening 24L and a spill port 24S communicating with the atmosphere. A valve element 241 is formed with a through hole 241H. When the solenoid valve 24 is opened, the second oil supply passage 22 temporarily communicates with the spill port 24S through the upper opening 24U and through hole 241H. Therefore, hydraulic pressure on the upper side of the needle piston 103 is immediately reduced, and the delay at the time when changing the valve operating characteristic is prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for changing the valve operating characteristics of an engine, for example, an apparatus for changing the operating characteristics of a valve for a so-called compression release brake that opens the exhaust valve at the end of the compression stroke to obtain a powerful braking effect of the engine brake. The present invention relates to the structure of a solenoid valve used in, for example.

  In a vehicle equipped with a diesel engine or a gasoline engine, it is desirable to apply a braking force to the vehicle by applying an engine brake while the vehicle is decelerating or traveling downhill. Normally, engine braking uses pumping loss, friction loss, etc. when the engine is driven backward from the vehicle wheel, but the exhaust valve is opened at the end of the compression stroke to obtain a stronger braking effect. Compression release brakes are known. This discharges compressed air in the cylinder at the end of the compression stroke, and generates negative work as a compressor, that is, an engine. By adopting the compression release brake, especially on a heavy-duty truck equipped with a diesel engine, avoid excessive use of the brake system equipped on the wheel during downhill driving, etc. It is possible to reduce and prevent a reduction in braking force of the brake system due to occurrence of a fade phenomenon.

  There are various types of compression release brakes (see, for example, Japanese Patent No. 4129490), but a hydraulic system that controls the opening and closing of the exhaust valve is installed to release the compressed air in the cylinder at the end of the compression stroke. Many. In addition to the cam lobe (cam crest) that normally opens and closes the exhaust valve cam that operates the exhaust valve, a compression release cam lobe that slightly opens the exhaust valve from the end of the compression stroke is formed, and the exhaust valve There is a method of adjusting a clearance (gap) between the valve and a valve operating mechanism (such as a rocker arm) using a hydraulic mechanism (lash adjuster). In this system, a gap is provided during normal operation of the engine to disable the opening of the exhaust valve by the compression release cam lobe. On the other hand, when the compression release brake is applied, the clearance is set to 0 and the exhaust valve is opened by the compression release cam lobe. , Release compressed air.

An example of the above-described compression release brake is disclosed in U.S. Pat. No. 3,867,792, which will be described with reference to FIGS.
FIG. 4 schematically shows a main part of a diesel engine provided with the above-described compression release brake. A cylinder head 3 is placed above the cylinder 2 where the piston 1 reciprocates. The cylinder head 3 is provided with an exhaust valve 5 that opens and closes in synchronization with the rotation of the crankshaft 4. The exhaust valve 5 is opened and closed by a valve mechanism such as a rocker arm 6, push rod 7, tappet 8 and the like. Although not shown, the cylinder head 3 is provided with an intake valve in parallel with the exhaust valve 5, and similarly to the exhaust valve 5, it is also opened and closed by a valve mechanism.

  An exhaust valve cam 9 that drives the exhaust valve 5 while rotating at half the rotational speed of the crankshaft 4 is disposed on the side of the cylinder 2. As shown in the enlarged view on the left side, the exhaust valve cam 9 slightly displaces the exhaust valve 5 between a normal cam lobe portion 91 that opens the exhaust valve 5 and a so-called base circle portion 92 where the exhaust valve 5 is closed. A compression release cam lobe 93 for lifting (about 1 mm) is provided. A hydraulic lash adjuster 10 is installed at the end of the rocker arm 6 that engages with the push rod 7. The lash adjuster 10 adjusts the clearance between the exhaust valve 5 and the exhaust valve cam 9. As shown in FIG. 5, the lash adjuster 10 is disposed above the hydraulic piston 101 and the hydraulic piston 101 with which the push rod 7 is engaged. A ball check valve 102 for forming a hydraulic chamber, a needle piston 103 formed with a needle abutting on the ball check valve 102, and the like are configured.

  Pressure oil of engine lubricating oil can be introduced above and below the needle piston 103 through an inlet provided in the casing of the lash adjuster 10. As shown in FIGS. 5 and 6, the rocker shaft 11 fixed to the cylinder head 3 is provided with a first oil supply passage 21, and engine lubricating oil is supplied from the lubricating oil pump 12 (FIG. 4) to the first oil supply passage. 21, and then introduced into the lower chamber 103 </ b> L below the needle piston 103. The rocker shaft 11 is also provided with a second oil supply passage 22 for introducing pressure oil into the upper chamber 103U above the needle piston 103, and is connected to a connecting portion 23 for connecting the two oil supply passages 21 and 22. As shown in FIG. 6, an electromagnetic valve 24 for opening and closing the connecting portion 23 by a ball-shaped valve body 24V is provided.

  When the compression release brake is applied to the diesel engine, the solenoid valve 24 is closed (at the same time, the fuel injection is cut), and the pressure oil of the lubricating oil supplied to the first oil supply passage 21 is provided to the rocker arm 6 in the first pipe. It introduces only into the lower chamber 103L of the needle piston 103 through the passage. As shown in FIG. 5B, the pressure oil is pushed up against the spring 104 to push the needle piston 103 against the spring 104 so that the ball type check valve 102 is seated on the valve seat. Thus, the hydraulic chamber 105 having a small height is formed. The hydraulic chamber 105 acts as a “liquid column” that eliminates the clearance between the exhaust valve 5 and the exhaust valve cam 9, and the rocker arm 6 swings accurately following the cam profile of the exhaust valve cam 9. . That is, the exhaust valve 5 performs a slight lift even by the compression release cam lobe 93 as shown by the solid line of the valve lift characteristic in FIG. The braking force is applied.

  During normal operation of the diesel engine, the pressure oil in the first oil supply passage 21 is supplied to the lower chamber 103L of the needle piston 103 and the electromagnetic valve 24 is opened, so that the communication portion 23, the second oil supply passage 22 and the rocker arm 6 are opened. It is also introduced into the upper chamber 103U via the second pipe line provided in. As shown in FIG. 5A, the needle piston 103 on which the hydraulic pressure of the same pressure is applied vertically is pushed down by the spring 104 to separate the ball check valve 102 from the valve seat. As a result, even if the upper chamber of the hydraulic piston 101 communicates with the first oil supply passage 21 and the liquid column function of the hydraulic chamber 105 disappears and the exhaust valve cam 9 is pushed up by the push rod 7, the upper surface of the hydraulic piston 101 is maintained. The exhaust valve 5 does not lift until it comes into mechanical contact. That is, a substantial clearance is generated between the exhaust valve cam 9 and the exhaust valve 5, and the exhaust valve 5 is not lifted by the compression release cam lobe 93 as shown by the broken line of the valve lift characteristic in FIG. It operates like a normal engine exhaust valve.

In this way, a system in which a hydraulic lash adjuster is interposed between the exhaust valve and the valve operating mechanism and the operation of the compression release brake is controlled by the two oil supply passages is hereinafter referred to as “two-system oil supply type compression release brake”. Call. This type of compression release brake has the advantage that it can be installed without significantly changing the engine layout and the like, and the cost is relatively low. In the above-described example, in the valve operating mechanism using the push rod, the lash adjuster is disposed between the push rod and the rocker arm. However, the lash adjuster is disposed between the exhaust valve cam and the push rod. It can also be provided on the tappet. In addition, for a so-called OHC engine in which the push rod is eliminated and the camshaft is provided above the cylinder head and the rocker arm is directly swung by the exhaust valve cam to drive the exhaust valve, the lash adjuster is connected between the rocker arm and the exhaust valve. It is obvious that the dual oil supply type compression release brake can be adopted by means such as being disposed between them.
The method of interposing a hydraulic lash adjuster between the valve and the valve operating mechanism is not limited to the compression release brake, and can be applied to various valve operating characteristic changing devices. For example, a device that changes the lift and open / close timing of the intake / exhaust valve according to the low-speed rotation and high-speed rotation of the engine, or a small cam lobe in the exhaust valve cam that opens the exhaust valve by a small amount during the intake stroke and sucks the exhaust gas. In a so-called engine with internal EGR to be returned, the engine can be used as a control device that controls the operation and inactivity of the internal EGR.

Japanese Patent No. 4129490 US Pat. No. 3,786,792

  In a valve operating characteristic changing device with a lash adjuster interposed, for example, a two-system oil supply type compression release brake, the solenoid valve is used to switch the communication state of the two system oil supply paths, and the hydraulic pressure acting on the top and bottom of the needle piston of the lash adjuster is changed. Change to control the operation and non-operation of the compression release brake. Since this control method is only an operation of switching the opening and closing of the solenoid valve, stable and reliable control can be executed, and there are few operation parts and it is economically excellent. However, with this type of compression release brake, it has been found that the following problems occur particularly when the engine speed increases.

In the two-system oil supply type compression release brake, a first oil supply passage 21 connected to the lower chamber 103L of the needle piston 103 and a second oil supply passage 22 connected to the upper chamber 103U are provided, and the solenoid valve 24 is provided during normal operation of the engine. When is opened, pressure oil is also supplied to the second oil supply passage 22 connected to the upper chamber 103U, and the hydraulic pressure in the upper chamber 103U is maintained at a constant value. When the solenoid valve 24 is closed to operate the compression release brake, the hydraulic pressure in the upper chamber 103U does not decrease instantaneously, and the needle piston 103 for moving the ball check valve 102 moves upward. It will be late. In other words, even if the solenoid valve is switched to apply a strong engine brake, a delay occurs in the actual start of operation of the compression release brake, and this delay increases the engine speed and the inertial force acting on the needle piston. It becomes more prominent as it grows larger. Such operation delay is a problem common to the valve operation characteristic changing device that switches the communication state of the two oil supply passages using the electromagnetic valve.
The present invention eliminates the above-described operation delay in a control device that controls a valve operating characteristic changing device using a lash adjuster with two oil supply passages, and improves responsiveness when switching the opening and closing of a solenoid valve. Let it be an issue.

In view of the above problems, the present invention is to provide a spill port opened to atmospheric pressure in a solenoid valve that switches the communication state of two oil supply passages, and to form a hydraulic chamber in which pressure oil is sealed in a lash adjuster. When closing the solenoid valve, the second oil supply passage connected to the upper chamber of the needle piston is temporarily connected to the spill port, so that the pressure in the upper chamber is immediately reduced and the operation delay of the valve operating characteristic changing device is prevented. To do. That is, the present invention
“A valve operating characteristic changing device for an engine in which a hydraulic lash adjuster is interposed between a valve arranged in a cylinder head and a cam for opening and closing the valve,
The lash adjuster includes a check valve that forms a hydraulic chamber filled with pressure oil, and a needle piston that releases the check valve to eliminate the hydraulic chamber,
A first oil supply passage for supplying pressure oil to one side of the needle piston, and a second oil supply passage for introducing the pressure oil of the first oil supply passage to the other side of the needle piston, and A solenoid valve is placed at the communication portion between the first oil supply passage and the second oil supply passage,
When the electromagnetic valve is closed, the first oil supply passage and the second oil supply passage are shut off to form the hydraulic chamber of the lash adjuster, and when the electromagnetic valve is opened, the first oil supply passage is formed. An oil supply passage is communicated with the second oil supply passage, and the check valve of the lash adjuster is opened by the needle piston.
The solenoid valve is provided with a spill port opened to atmospheric pressure, and when the solenoid valve is closed, the second oil supply passage is temporarily connected to the spill port.
This is an engine valve operating characteristic changing device.

  According to a second aspect of the present invention, there is provided a valve operating characteristic changing device for a compression release brake, that is, “a valve disposed in the cylinder head is an exhaust valve, and the exhaust valve is driven to open and close. The cam has a compression release cam lobe that slightly opens the exhaust valve at the end of the compression stroke for the compression release brake. When the solenoid valve is closed, the hydraulic chamber is formed in the lash adjuster, This is suitable for an engine valve operating characteristic changing device in which a release brake is operated.

  As the electromagnetic valve for temporarily communicating the second oil supply passage with the spill port, as described in claim 3, "a through hole is formed in the valve body of the electromagnetic valve, and the casing of the electromagnetic valve A side wall on which the valve body slides is provided, and an opening of the second oil supply passage and the spill port is formed on the side wall. When the electromagnetic valve is closed, the side wall is formed through the through hole. 2 oil supply passages may be temporarily communicated with the spill port. " Further, as described in claim 4, "the valve body of the solenoid valve is a sphere, and two valve seats are provided at opposing positions on the casing of the solenoid valve, and one valve seat is When the solenoid valve is closed, the second oil supply passage is temporarily communicated with the spill port via the one valve seat when the solenoid valve is closed.

The intake / exhaust valve and the valve mechanism of the engine perform high-speed motion such as reciprocation while synchronizing with rotation of the crankshaft. For this reason, a valve operating characteristic changing device that changes the operating characteristic of the valve is required to have rapid response that changes the operating characteristic in response to a change in the situation quickly. In the valve operating characteristic changing device to which the present invention is applied, that is, in the valve operating characteristic changing device that controls the formation of the hydraulic chamber in the lash adjuster by switching the two oil supply passages by the electromagnetic valve, the electromagnetic valve is particularly closed. When this occurs, the hydraulic pressure in the upper chamber (the other side) of the needle piston must be instantaneously reduced to immediately close the ball check valve to form a hydraulic chamber.
In the present invention, the spill port opened to the atmospheric pressure is provided in the electromagnetic valve placed in the communication part of the two oil supply passages. When the electromagnetic valve is closed, the spill port is connected to the upper chamber of the needle piston. The second oil supply passage is temporarily communicated with the spill port, and a part of the pressure oil is allowed to flow out. As a result, the hydraulic pressure in the upper chamber of the needle piston drops instantaneously in the process of closing the solenoid valve, the needle piston rises due to the pressure difference generated between the upper chamber and the lower chamber, and the ball check valve Close promptly. When the closed solenoid valve is opened, the second oil supply passage communicates with the spill port. However, since the hydraulic pressure of the second oil supply passage when the solenoid valve is closed is very low, the second oil supply passage communicates with the spill port. However, the pressure oil hardly flows out, and there is no adverse effect such as a delay in the lowering of the needle piston.

  As in the invention of claim 2, the present invention is a valve operating characteristic changing device for a compression releasing brake, that is, a valve operating characteristic changing device in which a compression releasing cam lobe that slightly opens an exhaust valve at the end of the compression stroke is formed. When this is applied to, the operation delay is prevented when the compression release brake is operated by forming the hydraulic chamber of the lash adjuster by closing the electromagnetic valve. Therefore, when the driver intends to operate the compression release brake, it is possible to immediately increase the braking force of the vehicle, and it is possible to avoid a danger associated with a delay in the vehicle speed reduction.

  According to a third aspect of the present invention, a side wall on which the valve body slides is provided in the casing of the electromagnetic valve to open the spill port, and a through hole is formed in the valve body of the electromagnetic valve. The oil supply passage communicates with the spill port. According to this, for example, when the present invention is applied to an engine with a different displacement, the opening area of the spill port or the shape of the through hole can be adjusted to obtain a response with desired characteristics. In the invention of claim 4, the valve body of the electromagnetic valve is a spherical body, and two valve seats are provided at positions facing the casing of the electromagnetic valve, and one valve seat communicates with the spill port. Also by this, the same effect as the above can be achieved with a simple configuration.

It is a figure which shows roughly the valve operation characteristic change apparatus using the solenoid valve of this invention. It is a figure which shows the action | operation of the solenoid valve body in the Example of FIG. It is a figure which shows the modification of the solenoid valve of this invention. 1 is an overall view schematically showing a conventional engine equipped with a compression release brake. It is a figure which shows the principal part of the valve action characteristic change apparatus in the engine of FIG. It is a figure which shows the solenoid valve used for the valve action characteristic change apparatus of FIG.

  The present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the electromagnetic valve of the present invention is applied to a two-system oil supply type compression release brake which is an example of a valve operating characteristic changing device. However, the basic structure of the compression release brake that controls the lash adjuster with the two oil supply passages is not different from the conventional one shown in FIGS. 4 to 6, so FIG. 1 shows the components shown in FIGS. Corresponding parts are denoted by the same reference numerals, and the basic structure other than necessary parts is schematically illustrated.

  A lash adjuster 10 that adjusts the clearance of the valve mechanism to control the operation and non-operation of the compression release brake is installed at the end of the rocker arm 6 that engages with the push rod 7, as shown in FIG. ing. The lash adjuster 10 includes a needle piston 103 in which a needle for controlling opening and closing of the ball check valve 102 is formed. In the state of FIG. 1 (corresponding to FIG. 5A), the lower chamber 103L of the needle piston 103 is provided. At the same time, hydraulic pressure is also introduced into the upper chamber 103U, and the needle piston 103 is pushed by the spring 104 to open the ball check valve 102. As a result, the hydraulic chamber above the hydraulic piston 101 disappears, and the compression release brake is inoperative (the engine is normally operated).

  The solenoid valve 24 of the present invention is placed in a communication portion between the first oil supply passage 21 for introducing pressure oil into the lower chamber 103L of the needle piston 103 and the second oil supply passage 22 for introducing pressure oil into the upper chamber 103U. Yes. Although the details of the structure of the electromagnetic valve 24 will be described later, in the state of FIG. 1, the valve body 241 of the electromagnetic valve 24 is pushed up by the push-up spring 242 and separated from the valve seat 243, and the electromagnetic valve 24 is opened. The engine lubricating oil is introduced from the lubricating oil pump 12 into the lower chamber 103L through the first oil supply passage 21 and simultaneously into the upper chamber 103U through the electromagnetic valve 24 and the second oil supply passage 22. The In this embodiment, the second oil supply path 22 is connected to a return pipe 25 that returns the lubricating oil to the oil pan, and in the middle of the return pipe 25 so as to keep the hydraulic pressure of the lubricating oil introduced into the upper chamber 103U at a constant value. Is provided with an orifice 26.

Next, the detailed structure and operation of the electromagnetic valve 24 of the present invention shown in FIG. 1 will be described with reference to FIG.
The electromagnetic valve 24 includes a coil 244 through which a current is applied, a fixed iron core 245 that generates a magnetic force when the coil 244 is energized, and a movable iron core 246 that is attracted to the fixed iron core 245, and the valve body 241 is moved by a rod 247. It is connected to the iron core 246. The peripheral portion of the lower end surface of the valve body 241 is in contact with the valve seat 243 to form a seal surface, and a push-up spring 242 for raising the valve body 241 is in contact with the lower end surface. The valve body 241 slides in a hole formed in the valve casing 248 below the fixed iron core 245 to control opening and closing of the valve seat 243.

  An opening communicating with the first oil supply passage 21 is provided at the lower part of the valve casing 248, and an upper opening 24U and a lower opening 24L communicating with the second oil supply passage 22 are provided at the side of the valve casing 248. A spill port 24S is provided at an intermediate position between the opening 24U and the lower opening 24L. The spill port 24S is connected to an oil pan by a drain pipe 27 and is substantially opened to atmospheric pressure. The upper opening 24U, the lower opening 24L, and the spill port 24S are opened in the side walls of the hole of the valve casing 248 on which the valve body 241 slides, and the valve body 241 is formed with a through hole 241H penetrating therethrough. The

In the state of FIG. 1, the energization to the coil 244 is interrupted, the valve body 241 of the electromagnetic valve 24 is separated from the valve seat 243 by the push-up spring 242, and the second oil supply path 22 is connected to the first oil supply path 21 via the lower opening 24L. Communicating with the compression release brake is disabled. At this time, the spill port 24S is blocked by the side surface of the valve body 241, and the upper opening 24U communicates with the through hole 241H, but is also blocked by the side wall of the hole of the valve casing 248. is there.
When the coil 244 is energized to operate the compression release brake, the movable iron core 246 is attracted to the fixed iron core 245, and the valve body 241 moves downward while compressing the push-up spring 242. In the process, as shown in FIG. 2B, the second oil supply passage 22 temporarily opens to the spill port 24S via the upper opening 24U and the through hole 241H. Since the spill port 24S is substantially in communication with the atmospheric pressure, the hydraulic pressure in the second oil supply passage 22 (when the compression release brake in which the electromagnetic valve 24 is open) is not operated due to this opening, the first oil supply passage 21 is almost the same. (Equal to the hydraulic pressure inside) decreases instantaneously and lowers the hydraulic pressure in the upper chamber 103U of the needle piston 103. Therefore, the needle piston 103 is immediately raised by the hydraulic pressure in the lower chamber 103L, and the ball check valve 102 is closed.

  Thus, when the compression release brake is operated, the ball check valve 102 is closed immediately in response to the energization of the coil 244, and the exhaust valve is lifted at the end of the compression stroke to increase the braking force. . When the valve body 241 is lowered to a position where the valve seat 243 is closed, as shown in FIG. 2C, the upper opening 24U and the through hole 241H are blocked, and the second oil supply path 22 is connected to the first oil supply path 21. Is disconnected and the spill port 24S is also disconnected. Even when the solenoid valve 24 is opened and the engine is operated normally, the spill port 24S is temporarily connected to the upper opening 24U. At this time, the hydraulic pressure of the second oil supply path 22 is very low. , There is no substantial adverse effect due to temporary communication.

A modification of the solenoid valve of the present invention is shown in FIG. In FIG. 3, the same reference numerals are given to the components corresponding to the components in FIG. 1.
The electromagnetic valve of the modified example is placed in a communicating portion between the first oil supply passage 21 and the second oil supply passage 22 like the electromagnetic valve of FIG. 1, and the first oil supply passage 21 is provided on the lower surface of the valve casing 248. Is provided with an opening 21 </ b> P that is continuous with the second oil supply passage 22. The valve body 241 is a spherical body, and two valve seats 243U and 243L are formed in the valve casing 248 at upper and lower positions facing each other. A lower end portion of a rod 247 connected to a movable iron core (not shown) is provided at the upper end of the valve body 241, and a push-up spring 242 for raising the valve body 241 is provided at the lower end of the valve body 241. It touches. An enlarged diameter portion 247D is formed at an intermediate portion of the rod 247, and the enlarged diameter portion 247D controls opening and closing of a spill port 24S provided on the side surface of the valve casing 248 above the upper valve seat 243U.

The state of FIG. 3A corresponds to the state of FIG. 1 in which the compression release brake is inoperative. The valve body 241 of the electromagnetic valve is separated from the lower valve seat 243L by the push-up spring 242 and the second oil supply path 22 communicates with the first oil supply passage 21 through the openings 21P and 22P. At this time, since the valve body 241 closes the upper valve seat 243U, the spill port 24S is cut off from the first oil supply passage 21 and the second oil supply passage 22.
When the solenoid valve coil is energized to operate the compression release brake and the rod 247 is lowered together with the movable iron core, the spherical valve body 241 is separated from the upper valve seat 243U, and the second oil supply path 22 is connected via the valve seat 243U. The spill port 24S is temporarily opened. Since the spill port 24S is substantially in communication with the atmospheric pressure, the hydraulic pressure in the second oil supply passage 22 is instantaneously lowered by this opening, and a ball type check valve (not shown) is closed and compressed and released. The brake works without delay. When the rod 247 is completely lowered and the valve body 241 closes the lower valve seat 243L, the enlarged diameter portion 247D closes the spill port 24S, as shown in FIG. Block communication with 24S.

  As described above in detail, the present invention relates to a solenoid valve used in a valve operating characteristic changing device that controls a lash adjuster with two oil supply passages. The solenoid valve is provided with a spill port opened to atmospheric pressure. When closing the solenoid valve, the oil supply passage connected to the upper chamber of the needle piston is temporarily connected to the spill port, thereby immediately reducing the pressure in the upper chamber and preventing the operation delay of the valve operating characteristic changing device. It is. In the above embodiment, an example is described in which the valve operating characteristic changing device for operating the compression release brake is described. However, the electromagnetic valve used in the device for changing the valve operating characteristic for the purpose of improving other engine performances. It is clear that this can also be applied. In the above embodiment, the pressure oil of the engine lubricating oil system is supplied to the lash adjuster or the like, but various modifications can be made to the above embodiment, such as supplying the pressure oil from another hydraulic system. It is clear that there is.

DESCRIPTION OF SYMBOLS 5 Exhaust valve 6 Rocker arm 7 Push rod 9 Exhaust valve cam 10 Rush adjuster 101 Hydraulic piston 102 Ball type check valve 103 Needle piston 12 Lubricating oil pump 21 1st oil supply path 22 2nd oil supply path 24 Electromagnetic valve 241 Valve body 241H Through-hole 242 Push-up spring 243 Valve seat 24U Upper opening 24L Lower opening 24S Spill port 244 Coil 245 Fixed iron core 246 Movable iron core

Claims (4)

A device for changing valve operating characteristics of an engine in which a hydraulic lash adjuster is interposed between a valve disposed on a cylinder head and a cam for driving to open and close the valve,
The lash adjuster includes a check valve that forms a hydraulic chamber filled with pressure oil, and a needle piston that opens the check valve and causes the hydraulic chamber to disappear.
A first oil supply passage for supplying pressure oil to one side of the needle piston, and a second oil supply passage for introducing the pressure oil of the first oil supply passage to the other side of the needle piston, and A solenoid valve is placed at the communication portion between the first oil supply passage and the second oil supply passage,
When the electromagnetic valve is closed, the first oil supply passage and the second oil supply passage are shut off to form the hydraulic chamber of the lash adjuster, and when the electromagnetic valve is opened, the first oil supply passage is formed. An oil supply passage is communicated with the second oil supply passage, and the check valve of the lash adjuster is opened by the needle piston.
The solenoid valve is provided with a spill port that is open to atmospheric pressure, and when the solenoid valve is closed, the second oil supply passage is temporarily communicated with the spill port. Valve operating characteristic changing device. The valve disposed in the cylinder head is an exhaust valve, and the cam that opens and closes the exhaust valve is formed with a compression release cam lobe that slightly opens the exhaust valve at the end of the compression stroke for the compression release brake. And
2. The engine valve operation characteristic changing device according to claim 1, wherein when the electromagnetic valve is closed, the hydraulic chamber is formed in the lash adjuster and a compression release brake is operated. A through hole is formed in the valve body of the solenoid valve, and a side wall on which the valve body slides is provided in the casing of the solenoid valve, and the second oil supply passage and the opening of the spill port are formed in the side wall. Is formed,
3. The engine valve operating characteristic changing device according to claim 1, wherein, when the electromagnetic valve is closed, the second oil supply passage is temporarily communicated with the spill port through the through hole. The valve body of the electromagnetic valve is a sphere, and two valve seats are provided at opposing positions on the casing of the electromagnetic valve, and one valve seat is communicated with the spill port,
3. The engine valve operating characteristic changing device according to claim 1, wherein when closing the electromagnetic valve, the second oil supply passage is temporarily communicated with the spill port via the one valve seat. 4. .

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