JP2008106724A - Variable valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear of an internal combustion engine capable of setting any compression ratio, realizing a combustion with less exhaust gas, improving the controllability of the engine by stabilizing oil temperature, and enhancing the durability of a solenoid valve. <P>SOLUTION: In this variable valve gear of an internal combustion engine, a block 7 having a hydraulic piston 13 retaining a rocker arm 6 by a hydraulic pressure in a hydraulic chamber 12 to hold an engine valve 2 in the open state and an oil path 16 introducing a hydraulic oil into the hydraulic chamber 12 through a check valve 14 and discharging it from the hydraulic chamber 12 through the solenoid valve 15 is disposed above the rocker arm 6 opening the engine valve 2 against a valve spring 5 by rotating a camshaft 3. The valve opening timing of the engine valve 2 is controlled by holding or releasing the pressure in the hydraulic chamber 12 by the solenoid valve 15. In the block 7, a cylindrical oil chamber 20 surrounding the solenoid valve 15, a communication path 21 allowing the oil chamber 20 to communicate with the oil path 16, and a discharge port 22 for discharging the hydraulic oil from the oil chamber 20 are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that changes a compression ratio by controlling a closing timing of an engine valve.

  In recent years, demand for reducing harmful components in exhaust gas from diesel engines has increased, and research on uniform premixed combustion capable of simultaneously reducing NOx and smoke in the exhaust gas has been conducted. This uniform premixed combustion is the simultaneous and frequent occurrence by injecting fuel into the cylinder at a timing earlier than usual (a timing earlier than the piston top dead center by a predetermined time or more) to generate a uniform mixture in the cylinder. This causes combustion. In order to realize this, control of the ignition timing is important, and a system capable of significantly lowering (changing) the compression ratio than in the case of normal combustion (diffusion combustion) is required.

  That is, in uniform premixed combustion, the uniform premixed gas in the cylinder is gradually compressed as the piston rises. At this time, if the compression ratio is the same as in normal combustion, the piston is at top dead center. It is conceivable that spontaneous ignition will occur before it reaches, and negative work will be done on the crankshaft. In order to avoid this, it is necessary to lower the compression ratio so that the air-fuel mixture does not ignite before the piston reaches the top dead center, and the ignition timing is in the vicinity of the top dead center.

  Conventionally, as a technology for making the compression ratio variable, there are known a method in which the phase of the intake camshaft is made variable (phase variable method) and a method in which the lift of the engine valve (intake and exhaust valve) is made variable (cam switching method). However, it has been difficult to make the compression ratio significantly and arbitrarily variable.

  On the other hand, there is a variable valve operating system for an internal combustion engine that uses a hydraulic piston and a solenoid valve to maintain the open state of the engine valve and control the valve closing timing, thereby making it possible to make the compression ratio significantly variable. It has been proposed (see Patent Document 1 and Patent Document 2). As shown in FIG. 4, this variable valve operating apparatus is configured such that an engine valve such as an intake valve 2 is opened and closed against a valve spring 5 by rotation of a camshaft 3, and a rocker is driven by hydraulic pressure in a hydraulic chamber 12. A hydraulic piston 13 that holds the intake valve 2 in an open state by holding the arm 6, an introduction passage 26 that introduces hydraulic oil into the hydraulic chamber 12 via a check valve (not shown), and an electromagnetic valve from the hydraulic chamber 12 A block (actuator) 7 having a discharge passage 27 for discharging hydraulic oil via a (two-way solenoid valve) 15 is arranged.

  When the valve is opened, it is the same as a normal valve system, and the rocker arm 6 is pushed by the rotation of the camshaft 3, and the intake valve 2 is pushed down according to the movement to open the valve. At this time, since hydraulic pressure of hydraulic oil (for example, lubricating oil) is applied to the hydraulic chamber 12 of the hydraulic piston 13, the hydraulic piston 13 moves downward following the movement of the intake valve 2. With the movement, hydraulic oil flows into the hydraulic chamber 12 from the introduction passage 26.

  When the solenoid valve 15 is opened (opened) after the valve lift is maximized (fully opened), the hydraulic pressure in the hydraulic chamber 12 communicates with the discharge passage 27 and is released, so that the hydraulic pressure is adjusted in accordance with the movement of the camshaft 3. The piston 13 and the rocker arm 6 are raised and closed. When the opening timing of the electromagnetic valve 15 is delayed, the hydraulic oil in the hydraulic chamber 12 is held, and the intake valve 2 can be held down, that is, kept open without following the movement of the camshaft 3.

  When the electromagnetic valve 15 is opened after an arbitrary time, the hydraulic oil in the hydraulic chamber 12 is released and the intake valve 2 is closed. By changing the valve closing timing, the compression ratio can be changed significantly and arbitrarily. In this way, the hydraulic valve presser system can freely control the timing and time of closing the valve and can change the compression ratio significantly and arbitrarily, which is advantageous for measures against low emissions by uniform premixed combustion. It is.

Japanese Patent Laid-Open No. 7-233718 JP 2006-152943 A

  However, in the variable valve operating apparatus (variable compression ratio apparatus) using the hydraulic pressure and the electromagnetic valve as described above, the oil temperature of the hydraulic oil rises due to repeated insertion / extraction and compression of the hydraulic oil in the hydraulic chamber 12, so that the intake air The valve opening characteristic or controllability of the valve 2 may be reduced, or the electromagnetic valve 15 itself may generate heat, which may cause overheating damage to the electromagnetic valve 15 or decrease in durability.

  The present invention solves the above-described problems of the conventional technology, can set an arbitrary compression ratio, can realize combustion with less exhaust gas, improves controllability by stabilizing the oil temperature, and improves the solenoid valve. It is an object of the present invention to provide a variable valve operating apparatus for an internal combustion engine that can improve durability.

  Among the present inventions, the invention according to claim 1 is characterized in that the engine valve is held by pressing the rocker arm by the hydraulic pressure in the hydraulic chamber above the rocker arm that opens the engine valve against the valve spring by rotation of the camshaft. A block having a hydraulic piston that is held in an open state and an oil passage that introduces hydraulic oil into the hydraulic chamber via a check valve and discharges the hydraulic oil from the hydraulic chamber via a solenoid valve; In the variable valve operating apparatus for an internal combustion engine that controls the closing timing of the engine valve by holding or releasing the pressure of the hydraulic chamber by the electromagnetic valve, the block includes a cylindrical oil chamber surrounding the electromagnetic valve; A communication passage communicating the oil chamber and the oil passage, and a discharge port for discharging hydraulic oil from the oil chamber are provided.

  According to a second aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the first aspect, the oil passage includes an introduction passage for introducing hydraulic oil from the introduction port to the hydraulic chamber via a check valve, and a hydraulic chamber. The discharge passage is connected to the upstream side of the check valve of the introduction passage through a solenoid valve.

  According to a third aspect of the present invention, in the variable valve operating apparatus for an internal combustion engine according to the first aspect, a supply passage for supplying hydraulic oil to at least the camshaft and the rocker shaft is connected to the discharge port. And

  According to the present invention, it is possible to set an arbitrary compression ratio by adopting a variable valve system using hydraulic pressure and a solenoid valve, to realize combustion with less exhaust gas, and to distribute hydraulic oil around the solenoid valve. Thus, the solenoid valve is cooled and the oil temperature is stabilized, so that the controllability can be improved and the durability of the solenoid valve can be improved by stabilizing the oil temperature.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a variable valve operating apparatus for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the operation timing of an electromagnetic valve in normal operation and low compression ratio operation, and FIG. FIG.

  FIG. 1 shows a variable valve operating apparatus (variable compression ratio apparatus) 1 for an internal combustion engine according to the present embodiment, for example, an engine valve of a diesel engine capable of switching between a normal combustion (diffusion combustion) mode and a uniform premixed combustion mode. The example applied to the intake valve 2 is shown. In such a diesel engine, when switching from the normal combustion mode to the uniform premixed combustion mode, it is necessary to greatly reduce the compression ratio as described above. In order to achieve this, the variable valve operating apparatus 1 uses the camshaft. The intake valve 2 opened by the third cam 3a is kept open for a desired time regardless of the phase of the cam 3a, and a part of the air-fuel mixture in the cylinder flows back to the intake port 4 substantially. The compression ratio is lowered.

  The variable valve operating apparatus 1 includes a camshaft 3 that is rotated in synchronization with the rotation of a diesel engine, and a rocker that is driven by the camshaft 3 and opens the intake valve 2 of the diesel engine against a valve spring 5. An arm 6 and a block 7 constituting an actuator for holding the intake valve 2 by holding the rocker arm 6 to keep the intake valve 2 open and deactivating the pushing force to control the closing timing of the intake valve 2 are provided. Yes.

  The camshaft 3 is pivotally supported by a cylinder head or the like (not shown), and the rotation of the crankshaft of the diesel engine is transmitted via a chain, belt, gear, or the like. The camshaft 3 includes a cam 3a formed in a predetermined shape for opening and closing the intake valve 2.

  The rocker arm 6 is swingable around a rocker shaft 6a attached to a cylinder head or the like, and an input end which is one end portion of the rocker arm 6 extending leftward from the rocker shaft 6a. A bridge 10 is attached to the top of the intake valve 2 via an adjustment member 9 with an output end that is in contact with the cam 3a via a roller 8 and extends rightward from the rocker shaft 6a. It is in contact with. The adjusting member 9 is screwed from above into a screw hole formed in the rocker arm 6 and is fixed by a nut 9a. A slipper may be provided in place of the roller 8.

  The bridge 10 is mounted on the tops of the two intake valves 2 and is used to operate the two intake valves 2 together. Each intake valve 2 is urged in a valve closing direction (upward in the figure) by a valve spring 5, and a valve umbrella portion 2 a protruding into the cylinder is seated on a valve seat 4 a of the intake port 4. ing. When the bridge 10 is pushed downward against the valve spring 5, the valve head portion 2a is opened downwardly from the valve seat 4a. A guide hole 10a for guiding the vertical movement of the bridge 10 is formed in the bridge 10, and a guide rod 11 attached to a cylinder head or the like is inserted into the guide hole 10a.

  When the input end of the rocker arm 6 rides on the upslope of the cam 3a of the camshaft 3 through the roller 8 as the camshaft 3 rotates, the rocker arm 6 counterclockwise against the force of the valve spring 5 The intake valve 2 is pushed down against the force of the valve spring 5 and opened by the output end of the rocker arm 6 via the bridge 10. When the input end of the rocker arm 6 climbs over the top of the cam 3a, the intake valve 2 is in the maximum lift state (fully opened), and then the cam 3a further rotates so that the input end of the rocker arm 6 is connected to the cam 3a. When the apex is reached and the down slope is reached, each intake valve 2 is raised by the force of the valve spring 5, and finally each intake valve 2 is seated on the valve seat 4a and closed (fully closed).

  The block 7 is a component that characterizes the present embodiment, and includes a hydraulic chamber 12, and a hydraulic piston 13 that holds the intake valve 2 in an open state by pressing the rocker arm 6 by the hydraulic pressure of the hydraulic chamber 12. The hydraulic chamber 12 is provided with at least an oil passage 16 for introducing the hydraulic oil through the check valve 14 and discharging the hydraulic oil from the hydraulic chamber 12 through the electromagnetic valve 15. The block 7 is formed with a cylinder 17 into which a cylindrical hydraulic piston 13 is slidably inserted in an up-down direction, and is opened downward. An upper end of the hydraulic piston 13 in the upper part of the cylinder 17 is formed. The enclosed area is a hydraulic chamber 12. The lower end portion of the hydraulic piston 13 protrudes from the lower surface of the block 7 and is in contact with the upper portion of the output end of the rocker arm 6, that is, the upper end portion of the adjusting member 9 in the illustrated example. The block 7 is provided on, for example, a cylinder head cover.

  The oil passage 16 includes an introduction passage 16 a for introducing hydraulic oil from an introduction port 18 formed in the block 7 to the hydraulic chamber 12 through the check valve 14, and the introduction passage from the hydraulic chamber 12 through the electromagnetic valve 15. The exhaust passage 16b is connected mainly to the upstream side of the check valve 14 of 16a. An oil supply passage (not shown) for supplying hydraulic oil (lubricating oil) having a predetermined pressure from an oil pump is connected to the introduction port 18. The leading end portion of the introduction passage 16 a is connected to the side surface portion of the hydraulic chamber 12. The discharge passage 16b includes a first oil passage 16b1 that communicates the top of the hydraulic chamber 12 and a lower portion of the valve chamber 15a of the solenoid valve 15, and an annular second oil passage provided on the outer periphery of the lower portion of the valve chamber 15a. 16b2 and a second oil passage 16b2 and a third oil passage 16b3 communicating with the upstream side of the check valve 14 of the introduction passage 16a. The second oil passage 16b2 is preferably formed in a large volume so as to absorb and relieve high hydraulic pressure released from the hydraulic chamber 12.

  The solenoid valve 15 is composed of an on / off type two-way solenoid valve that opens and closes depending on the presence or absence of energization. The electromagnetic valve 15 includes a hollow cylindrical valve chamber 15a that is long in the vertical direction, a cylindrical valve body 15b that is slidably inserted in the vertical direction on the lower side of the valve chamber 15a, and the valve body. A spring 15c that constantly urges 15b in the valve closing direction (downward) and a solenoid 15d that urges and moves the valve body 15b in the opening direction (upward) against the spring 15c when energized (on). ing. The block 7 is preferably formed with a vent 15e that opens the upper side of the valve chamber 15a of the electromagnetic valve 15 to the atmosphere. The variable valve operating apparatus 1 includes a control unit 25 for controlling the opening and closing of the electromagnetic valve 15.

  The hydraulic oil supplied from the introduction port 18 to the introduction passage 16a is set to a pressure smaller than the force of the valve spring 5 of the intake valve 2 and actively resists the force of the valve spring 5 by the hydraulic piston 13. Although the intake valve 2 is not pushed down (opened), the pressure is such that the hydraulic piston 13 can be pushed down following the depression of the intake valve 2 by the rocker arm 6. In this case, hydraulic oil is introduced from the introduction passage 16a into the hydraulic chamber 12 via the check valve 14, whereby the hydraulic piston 13 is pushed downward in the cylinder 17 and the intake valve 2 reaches the fully open position. Even if the force of the valve spring 5 is applied to the hydraulic piston 13 after that, the hydraulic pressure in the hydraulic chamber 12 is sealed by the check valve 14 and the valve body 15b of the electromagnetic valve 15, so that the hydraulic piston 13 is pushed back. The rocker arm 6 and the intake valve 2 are held in the open position regardless of the rotation of the camshaft 3. When the solenoid valve 15 is turned on and opened after a predetermined time, the hydraulic pressure in the hydraulic chamber 12 is released through the discharge passage 16b, and the restriction of the hydraulic piston 13 is released. The valve is raised and closed, and the hydraulic piston 13 is also returned to its original position along with this. The excess hydraulic oil or hydraulic pressure released from the hydraulic chamber 12 to the discharge passage 16b by opening the electromagnetic valve 15 is pushed back from the inlet 18 to the oil supply passage.

  The block 7 surrounds the solenoid valve 15 in order to prevent the oil temperature of the hydraulic oil from rising and overheating due to heat generation of the solenoid valve 15 itself by repeatedly putting in and out of the hydraulic chamber 12 and repeated compression. A cylindrical cooling oil chamber (cooling chamber) 20, a communication passage 21 that connects the oil chamber 20 and the oil passage 16, and a discharge port 22 that discharges hydraulic oil from the oil chamber 20 are provided. Yes. In the illustrated example, the communication passage 21 is connected to the third oil passage 16b3, and the hydraulic oil released from the hydraulic chamber 12 passes through the oil chamber 20 for cooling the electromagnetic valve 15 from the third oil passage 16b3 and is discharged. Although it is discharged from the outlet 22 to the outside of the block 7, the communication passage 21 may be connected to the upstream side of the check valve 14 of the introduction passage 16a.

  The oil chamber 20 is formed in a vertically long and hollow annular or cylindrical shape so as to surround the solenoid 15d and the valve chamber 15a of the electromagnetic valve 15. One end of the communication passage 21 is connected to one side of the oil chamber 20, and a discharge port 22 is provided on the other side of the oil chamber 20. In this case, between the oil chamber 20 and the discharge port 22 in order to suppress the discharge amount of the hydraulic oil discharged or discharged from the discharge port 22 and to secure the oil amount or hydraulic pressure introduced into the hydraulic chamber 12. Is provided with a throttle (orifice) 23 for restricting the flow rate to a constant value. The discharge port 22 is connected to a supply passage (operating oil gallery) 24 that supplies hydraulic oil discharged from the outlet 22 to at least the camshaft 3 and the rocker shaft 6a.

  Next, the operation of the variable valve apparatus 1 having the above configuration will be described. When the diesel engine is normally burned using the variable valve operating apparatus 1, that is, when the engine is operated at a normal compression ratio, the input end of the rocker arm 6 becomes the upslope of the cam 3a as the camshaft 3 rotates. In the step of riding, the rocker arm 6 rotates clockwise to push down the intake valve 2 against the force of the valve spring 5 to open the valve. Here, since the lubricating oil is always supplied to the hydraulic chamber 12, and the electromagnetic valve 15 is closed at this time, the hydraulic piston 13 is rotated in response to the rocker arm 6 rotating clockwise as described above. Is moved downward by the pressure of the lubricating oil in the hydraulic chamber 12.

  Thereafter, when the rotation of the cam 3a advances and the input end of the rocker arm 6 passes over the apex of the cam 3a and approaches the down slope or immediately before reaching, the control unit 25 opens the solenoid valve 15 [see FIG. 2 (a). ], The hydraulic chamber 12 and the discharge passage 16b are connected to release the pressure of the lubricating oil in the hydraulic chamber 12. Then, the force that pushes down the hydraulic piston 13 is extinguished, so that the rocker arm 6 rotates counterclockwise as the input end of the rocker arm 6 moves down the down slope of the cam 3a as the cam 3a rotates. At the same time, the intake valve 2 is moved in the valve closing direction (upward) by the force of the valve spring 5, and the hydraulic piston 13 is pushed up accordingly, and the lubricating oil in the hydraulic chamber 12 is discharged from the discharge passage 16b.

  When the hydraulic piston 13 is fully raised, that is, when the input end of the rocker arm 6 has descended the down slope of the cam 3a and the intake valve 2 is completely closed, the control unit 25 closes the electromagnetic valve 15 [FIG. 2 (a)]. As a result, the pressure of the hydraulic oil in the hydraulic chamber 12 gradually increases and a force is generated in a direction to push down the hydraulic piston 13. At this time, this force rotates counterclockwise and becomes a valve closing posture. The rocker arm 6 is not so large as to rotate clockwise against the force of the valve spring 5, and the closed intake valve 2 is not opened.

  By repeating the opening / closing control of the solenoid valve 15 at the timing shown in FIG. 2A as described above, an operation at a normal compression ratio, that is, an operation by normal combustion becomes possible. Here, the timing of the opening / closing command of the solenoid valve 15 transmitted from the control unit 25 to the solenoid valve 15 is determined based on the rotation angle of the crankshaft or the camshaft 3. That is, the rotation angle of the crankshaft and / or camshaft 3 is always detected, and the detected value is applied to a map or the like stored in advance in the control unit 25, thereby determining the timing of the solenoid valve open / close command. It is done. Of course, during normal combustion operation, fuel is injected into the combustion chamber near the top dead center of the engine piston and ignited near the top dead center.

  Next, a case where the diesel engine is operated in a uniform premix combustion mode, that is, a case where the engine is operated at a compression ratio lower than that in a normal combustion mode will be described. Also in this case, when the input end of the rocker arm 6 rides on the up slope of the cam 3 a as the camshaft 3 rotates, the rocker arm 6 is rotated clockwise, and the intake valve 2 is forced by the valve spring 5. The intake valve 2 is finally pushed down to the maximum lift position at the top of the cam 3a. The operation until this operation is the same as that in the normal operation described above. Thereafter, as shown in FIG. 2B, the solenoid valve 15 is closed by the control unit 25 even after the intake valve 2 is pushed down to the maximum lift position. It has been.

  As a result, the lubricating oil in the hydraulic chamber 12 is continuously prevented from being discharged from the discharge passage 16b. Therefore, even if the input end of the rocker arm 6 reaches the down slope beyond the top of the cam 3a, the hydraulic piston 13 Is held down. That is, at this time, the force that pushes down the hydraulic piston 13 by the pressure of the hydraulic oil in the hydraulic chamber 12 counteracts the force of the valve spring 5 on the rocker arm 6 that rotates clockwise and is in the valve-opening posture. It is a force that can be held in that posture. As a result, regardless of the phase of the cam 3a, the rocker arm 6 is held in the valve-opening posture rotated clockwise, and the intake valve 2 is held in the state where it is pushed down to the maximum lift position. As a result, a part of the air-fuel mixture in the cylinder of the engine flows backward to the intake port 4 and the substantial compression ratio decreases.

  After that, if the intake valve 2 is held in the maximum lift state until the target compression ratio is lowered, the electromagnetic valve 15 is opened by the control unit 25, and the pressure of the hydraulic oil in the hydraulic chamber 12 is released to the discharge passage 16b. As a result, the pressure of the lubricating oil in the hydraulic chamber 12 decreases, and the force that pushes down the hydraulic piston 13 is the force of the valve spring 5 that rotates the rocker arm 6 in the valve-opening posture rotated clockwise. The intake valve 2 rises and closes, and the backflow ends. That is, the compression ratio can be arbitrarily changed by arbitrarily adjusting the valve opening timing A of the electromagnetic valve 15 shown in FIGS. The valve opening timing of the solenoid valve 15 varies depending on how much the compression ratio at the time of uniform premixed combustion is reduced relative to the compression ratio at the time of normal combustion. That is, the valve opening timing of the electromagnetic valve 15 is determined by always detecting the angle of the crankshaft and / or the camshaft 3 and applying the detected value to a map or the like stored in advance in the control unit 25. During uniform premixed combustion, fuel is injected into the engine cylinder at a timing earlier than that during normal combustion, and the uniform mixture generated by mixing with intake air in the cylinder is the top dead center of the piston. It will be ignited in the vicinity.

  On the other hand, a cylindrical oil chamber 20 is provided around the solenoid valve 15, and hydraulic oil is introduced into the oil chamber 20 from the oil passage 16 through the communication passage 21 and introduced into the oil chamber 20. Since the discharged hydraulic oil is discharged from the discharge port 22, even when the oil passage 16 is in a closed loop shape, the hydraulic oil continues to circulate through the oil passage 16 and is stored. However, the oil temperature of the hydraulic oil can be stabilized, and the electromagnetic valve 15 can be cooled by discharging the hydraulic oil through the oil chamber 20 on the outer periphery of the electromagnetic valve 15.

  According to the variable valve operating apparatus 1 of the diesel engine, an arbitrary compression ratio can be set by adopting the variable valve operating apparatus 1 using the hydraulic pressure and the electromagnetic valve 15, and combustion with less exhaust gas can be realized. Since the hydraulic oil is circulated around the valve 15 to cool the solenoid valve 15 and stabilize the oil temperature, the controllability can be improved and the durability of the solenoid valve 15 can be improved by stabilizing the oil temperature. .

  An oil passage 16 that introduces hydraulic oil into the hydraulic chamber 12 and discharges the hydraulic oil from the hydraulic chamber 12 includes an introduction passage 16 a that introduces the hydraulic oil from the introduction port 18 into the hydraulic chamber 12 via the check valve 14, and hydraulic pressure. The discharge passage 16b is connected from the chamber 12 through the electromagnetic valve 15 to the upstream side of the check valve 14 of the introduction passage 16a and is in a so-called closed loop shape, so that it is discharged from the hydraulic chamber 12. A part of the hydraulic oil can be supplied again to the hydraulic chamber 12 for circulation, and the amount of hydraulic oil discharged from the discharge port 22 can be suppressed.

  Further, since the discharge port 22 is provided with a throttle portion 23, the amount of hydraulic oil discharged from the discharge port 22 can be suppressed to be constant, and the hydraulic oil can be supplied to the hydraulic chamber 12. The amount of oil can be secured.

  Further, since the supply passage 24 for supplying the hydraulic oil to the camshaft 3 and the rocker shaft 6a is connected to the discharge port 22, the discharge port 22 is used for driving the hydraulic piston 13 in the variable valve operating apparatus 1, and the solenoid valve. The hydraulic oil used for cooling 15 can also be used for lubricating the camshaft 3 and the rocker shaft 6a, and the hydraulic oil can be effectively utilized.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the gist of the present invention. . For example, the exhaust valve may be controlled as an engine valve in the same manner as the intake valve.

  The variable valve operating apparatus 1 is not limited to application to a diesel engine that switches between normal operation and uniform premixed combustion operation, but is applied to a diesel engine that performs only normal operation or only uniform premixed combustion operation. Is also possible.

It is the schematic which shows the variable valve apparatus of the internal combustion engine which concerns on embodiment of this invention. It is explanatory drawing explaining the action | operation time of the solenoid valve in a normal driving | operation and a low compression ratio driving | operation. It is an engine valve opening / closing process diagram. It is the schematic which shows an example of the conventional variable valve apparatus.

Explanation of symbols

1 Variable valve gear 2 Intake valve (engine valve)
3 Camshaft 5 Valve Spring 6 Rocker Arm 7 Block 12 Hydraulic Chamber 13 Hydraulic Piston 14 Check Valve 15 Solenoid Valve 16 Oil Path 20 Oil Chamber 21 Communication Path 22 Discharge Port 23 Throttle Portion

Claims (3)

  A hydraulic piston that holds the engine valve in an open state by pressing the rocker arm by the hydraulic pressure of the hydraulic chamber above the rocker arm that opens the engine valve against the valve spring by rotation of the camshaft, and the hydraulic chamber A block having an oil passage for introducing hydraulic oil through a check valve and discharging hydraulic oil from the hydraulic chamber through a solenoid valve, and holding or releasing the pressure in the hydraulic chamber by the solenoid valve. In the variable valve operating apparatus for an internal combustion engine that controls the valve closing timing of the engine valve, the block includes a cylindrical oil chamber surrounding the solenoid valve, and a communication passage that communicates the oil chamber with the oil passage. A variable valve operating apparatus for an internal combustion engine, comprising: a discharge port for discharging hydraulic oil from the oil chamber.   The oil passage includes an introduction passage for introducing hydraulic oil into the hydraulic chamber from the introduction port via the check valve, and a discharge connected to the upstream side of the introduction passage from the hydraulic chamber via the solenoid valve. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, further comprising a passage.   2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a supply passage for supplying hydraulic oil to at least the camshaft and the rocker shaft is connected to the discharge port.

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