JP2009079475A - Variable valve train for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology capable of improving startability of a variable valve train at engine start in an internal combustion engine provided with a vane type variable valve train. <P>SOLUTION: Air residing in either a retarding passage L3 or an advancing passage L4 and flowing into either a retarding oil pressure chamber 35 or an advancing oil pressure chamber 36 before working oil is discharged to another via a bypass passage L5 keeping communication between the retarding oil pressure chamber 35 and the advancing oil pressure chamber 36. Continuity of the bypass passage L5 is maintained by keeping a second spool 52 at a continue position while the air is discharged via the bypass passage L5. The second spool 52 is moved to a shut off position to shut off the bypass passage L5 at timing when discharge of the air via the bypass passage L5 is almost completed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vane variable valve mechanism for an internal combustion engine.

  In recent years, a variable valve mechanism that can change the opening / closing timing of at least one of an intake valve and an exhaust valve has been proposed as a valve mechanism of an internal combustion engine mounted on an automobile or the like.

  As the variable valve mechanism, for example, a housing that is connected to one of an output shaft of an internal combustion engine or a cam shaft that opens and closes at least one of an intake valve and an exhaust valve of the internal combustion engine and has a recess inside. And an inner rotor connected to the other of the output shaft and the cam shaft and rotatably disposed in the housing and having a vane that divides the recess into a retarded hydraulic chamber and an advanced hydraulic chamber. A variable valve mechanism is known.

  In this vane type variable valve mechanism, the hydraulic oil is supplied to and discharged from at least one of the retarded hydraulic chamber or the advanced hydraulic chamber and the relative hydraulic fluid pressure applied to the vane from the retarded hydraulic chamber and the advanced hydraulic chamber is increased. The opening / closing timing of the valve is changed by changing the height and rotating the inner rotor relative to the housing. That is, when the inner rotor is rotated in the rotation direction of the output shaft with respect to the housing, the rotation phase of the cam shaft relative to the output shaft advances, and the inner rotor rotates in the direction opposite to the rotation direction of the output shaft with respect to the housing. When it is moved, the rotational phase of the cam shaft relative to the output shaft is retarded.

  By the way, the vane rotation drive with respect to the housing in the vane type variable valve apparatus is generally performed by using the hydraulic pressure of the lubricating oil of the internal combustion engine (hereinafter, the oil for driving the vane is also referred to as “operating oil”). . That is, when the hydraulic pressure in the retarded hydraulic chamber or the advanced hydraulic chamber is increased, the hydraulic oil is pumped up from the oil pan by the oil pump that uses the rotational force of the output shaft of the internal combustion engine as a drive source, and is transferred to the retarded hydraulic chamber. The hydraulic oil is supplied to the advance hydraulic chamber and the retard hydraulic chamber via the retard oil passage and the advance oil passage which are the routes to the advance hydraulic chamber. On the other hand, when lowering the hydraulic pressure in the retarded hydraulic chamber or advanced hydraulic chamber, the hydraulic oil is discharged from the advanced hydraulic chamber or retarded hydraulic chamber via the retarded oil pathway or advanced hydraulic pathway, and this operation is performed. Oil is collected in an oil pan.

  Here, since the hydraulic oil in the retarded hydraulic chamber and the advanced hydraulic chamber is generally discharged when the internal combustion engine is stopped, the hydraulic oil is quickly supplied to the advanced hydraulic chamber or the retarded hydraulic chamber after restart. It is necessary to supply and fill, and to adapt the valve opening and closing timing to the operating conditions.

  By the way, a torque is applied to the camshaft to prevent rotation of the camshaft by friction such as a valve spring. Therefore, when the engine speed is low and the driving force of the oil pump is small, such as when the internal combustion engine is started, it is difficult to apply sufficient hydraulic pressure to the vane variable valve mechanism, and the camshaft receives the camshaft. There is a case where the responsiveness of the variable valve mechanism decreases due to fluctuations in the vanes of the internal rotor with respect to the housing due to the fluctuating torque.

In this regard, Patent Document 1 includes a communication path that communicates an advance hydraulic chamber and a retard hydraulic chamber formed in a housing, and fluctuating torque is applied to the camshaft in the direction of changing the rotational phase of the housing and the vane. A variable valve mechanism that changes the advance hydraulic chamber and the retard hydraulic chamber from the shut-off state to the conductive state only when acting is disclosed. In this technique, when the internal rotor is advanced with respect to the housing, the hydraulic oil is moved from the retarded hydraulic chamber to the advanced hydraulic chamber, and when the internal rotor is retarded with respect to the housing, the advanced hydraulic chamber is The responsiveness of the variable valve mechanism is improved by moving the hydraulic oil from the hydraulic pressure chamber to the retarded hydraulic chamber.
JP 2005-330892 A JP 2002-227617 A Japanese Patent Laid-Open No. 11-229828

  However, when the internal combustion engine is stopped, the hydraulic oil is discharged from the retarded hydraulic chamber and the advanced hydraulic chamber as described above, and air may remain in the retarded oil path or the advanced oil path. is there. Therefore, when supplying hydraulic oil to the advance hydraulic chamber or retard hydraulic chamber to operate the variable valve mechanism at the start of the internal combustion engine, the hydraulic oil is supplied while pushing out the accumulated air. Prior to the oil, air flows into the advance hydraulic chamber or the retard hydraulic chamber.

  Accordingly, the start timing of the variable valve mechanism may be delayed unless air is quickly discharged from the hydraulic chamber to which hydraulic oil is supplied. As a result, the startability of the variable valve mechanism at the time of engine start may deteriorate, leading to deterioration of emissions or drivability. However, in the above-mentioned patent documents and the like, air that stays in the retard oil passage or advance oil passage and flows in before hydraulic oil at the time of engine start or air that stays in the hydraulic chamber There is no disclosure about the technology for discharging from the room.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the startability of the variable valve mechanism at the time of engine start in an internal combustion engine having a vane variable valve mechanism. Is to provide.

In order to achieve the above object, the variable valve mechanism for an internal combustion engine according to the present invention employs the following means. That is,
A housing connected to one of the output shaft of the internal combustion engine or at least one of the intake valve and the exhaust valve of the internal combustion engine and having a recess therein, and the other of the output shaft and the cam shaft And an internal rotor having a vane that is rotatably arranged in the housing and partitions the recess into a retarded hydraulic chamber and an advanced hydraulic chamber, and at least the retarded hydraulic chamber or the advanced angle Supplying / exhausting hydraulic oil to / from one of the hydraulic chambers, changing the relative magnitude of the hydraulic pressure applied to the vanes from the retard hydraulic chamber and the advance hydraulic chamber, and changing the internal rotor to the housing In a variable valve mechanism for an internal combustion engine that changes the opening and closing timing of the valve by relative rotation,
An air vent communication passage that is formed in the vane and communicates with the retard hydraulic chamber and the advance hydraulic chamber, and discharges air that flows into one of the retard hydraulic chamber or the advance hydraulic chamber to the other;
A valve mechanism that shuts off the air vent communication passage at a timing when the discharge of air through the air vent communication passage is substantially completed;
Is further provided.

  In the above configuration, the hydraulic oil is supplied via the retard oil path that is the hydraulic oil supply / discharge path to the retard hydraulic chamber and the advance oil path that is the hydraulic oil supply / discharge path to the advance hydraulic chamber. Excretion is performed. Further, since the hydraulic oil supplied to the retard hydraulic chamber and the advance hydraulic chamber is once discharged when the engine stops, when the engine is started, the advance hydraulic chamber or the retard hydraulic chamber is started to start the variable valve mechanism. Hydraulic oil is supplied to one of the angular hydraulic chambers. For example, when the internal rotor is retarded with respect to the housing, hydraulic oil is supplied to the retarded hydraulic chamber via the retarded oil path, and when advanced, the advanced hydraulic chamber is communicated via the advanced oil path. Is supplied with hydraulic oil.

In the present invention, the hydraulic pressure of the retarded hydraulic chamber or the advanced hydraulic chamber to which the hydraulic oil is supplied via the air vent communication passage formed in the vane and communicating with the retarded hydraulic chamber and the advanced hydraulic chamber. The air flowing into the chamber was discharged to the other side.

  Here, the air that has flowed into the retarded hydraulic chamber or the advanced hydraulic chamber is the air that has stayed in the retarded oil passage or the advanced hydraulic pathway, and is the retarded hydraulic chamber prior to the hydraulic oil after the engine is started. In addition to the air flowing into the advance hydraulic chamber, the air staying in the retard hydraulic chamber or the advance hydraulic chamber while the engine is stopped is also included. As a result, when the hydraulic oil is supplied to the retard hydraulic chamber or the advanced hydraulic chamber when the engine is started, the air in the hydraulic chamber to which the hydraulic oil is supplied can be discharged to the other hydraulic chamber. Air discharged to the other of the retarded hydraulic chamber or the advanced hydraulic chamber via the air vent communication passage is discharged to the hydraulic oil storage tank (for example, an oil pan) from the advanced oil channel or the retarded oil channel. You may do it.

  Further, the valve mechanism in the present invention shuts off the air vent communication passage at the timing when the discharge of air through the air vent communication passage is almost completed. That is, after the discharge of air through the air vent communication passage is finished, hydraulic oil is supplied to the retarded hydraulic chamber or the advance hydraulic chamber, so by blocking the air vent communication passage, The hydraulic oil supplied to the hydraulic chamber is prevented from flowing into the other hydraulic chamber.

  Note that the “timing at which the discharge of air through the air vent communication passage substantially ends” is a concept including the timing at which the discharge of air from the retarded hydraulic chamber or the advanced hydraulic chamber ends, and the timing before and after that timing. is there. For example, the valve mechanism according to the present invention may block the air vent communication passage at the timing when the inflow of air into the retarded hydraulic chamber or the advanced hydraulic chamber is completed and the supply of hydraulic oil is started. Even in this case, the discharge of air through the air vent communication passage is almost completed, and the filling of the hydraulic oil at the time of starting the engine can be completed earlier than in the case where the present invention is not applied. Further, in order to ensure the reliable discharge of air, the timing at which the air vent communication path is blocked may be slightly later than the timing at which the discharge of air ends.

  As described above, according to the present invention, when hydraulic oil is supplied to one of the retarded hydraulic chamber or the advanced hydraulic chamber at the start of the internal combustion engine, the air that has flowed into the hydraulic chamber to which hydraulic fluid is supplied. The start of the variable valve mechanism can be realized at an early stage by discharging the air or the air staying in the hydraulic chamber. That is, it is possible to improve the startability of the variable valve mechanism when starting the engine. Further, since the opening / closing timing of the intake valve or the exhaust valve can be quickly adapted to the operating state of the internal combustion engine when the engine is started, exhaust emission and drivability can be improved.

  In addition, the valve mechanism in the present invention cuts off the storage chamber formed in the vane to which the air vent communication passage is connected and the conduction position that is accommodated in the storage chamber so as to be slidable back and forth and that conducts the flow path of the air vent communication passage. You may have a valve member which can move between the interruption | blocking positions, and the urging member which urges | biases a valve member to one side of a reciprocating direction, and hold | maintains this valve member in a conduction | electrical_connection position. An oil path for a valve mechanism is supplied to the storage chamber to supply hydraulic oil for pressing the valve member to the other side in the reciprocating direction and holding the valve member in a blocking position against the urging force of the urging member. The valve member may be formed with a small-diameter passage that electrically connects the valve mechanism oil passage and the air vent communication passage when the valve member is held at least in the conduction position.

  In the variable valve mechanism having the valve mechanism configured as described above, the timing at which the discharge of air through the air vent communication passage ends and the discharge of the air remaining in the valve mechanism oil passage through the small diameter passage are reduced. The hydraulic oil may be supplied to the valve mechanism from the valve mechanism oil path so that the timing of the completion substantially matches.

In the above configuration, air stays in the valve mechanism oil passage in the same manner as the retard oil passage or the advance oil passage. Therefore, when hydraulic oil is supplied to the valve mechanism from the valve mechanism oil path, air pressure first acts on the valve member. By the way, the air pressure acting on the valve member becomes higher than the urging force of the urging member while the air flowing into one of the retarded hydraulic chamber or the advanced hydraulic chamber is discharged from the air vent communication passage. As a result, the valve member may move from the conducting position to the blocking position. As a result, the air vent communication passage is blocked before the discharge of air from the retard hydraulic chamber or the advance hydraulic chamber via the air vent communication passage is completed.

  Therefore, in the present invention, the air staying in the oil passage for the valve mechanism is discharged to the air vent communication passage through the small diameter passage to suppress an excessive increase in air pressure acting on the valve member. Thereby, it is possible to suitably prevent the air vent communication path from being blocked before the discharge of air from the retard hydraulic chamber or the advance hydraulic chamber is completed.

  On the other hand, when the discharge of the air staying in the valve mechanism oil path through the small diameter passage is completed, the operation is switched to air and the hydraulic oil is supplied from the valve mechanism oil path, so that the hydraulic pressure acts on the valve member. To do. Since hydraulic oil has a very high viscosity compared to air and is difficult to circulate through a small diameter passage, pressure loss increases. As a result, the pressing force that presses the valve member becomes larger than the biasing force of the biasing member, whereby the valve member moves from the conducting position to the blocking position.

  In the present invention, the valve mechanism is configured so that the timing at which the discharge of air through the air vent communication passage is completed and the timing at which the discharge of the air staying in the valve mechanism oil passage through the small-diameter passage is completed substantially coincide. Hydraulic oil is supplied from the oil passage. Therefore, before the discharge of air through the air vent communication passage is completed, the valve member can be held at the conduction position by applying air pressure to the valve member. Further, after the discharge of air through the air vent communication passage is completed, the valve member can be switched to the shut-off position. Further, according to the above configuration, it is advantageous in terms of cost because it is possible to switch between conduction and blocking of the air vent communication passage with a simple configuration and timing by using the difference in viscosity between air and hydraulic oil.

  Further, according to the variable valve mechanism having the above-described configuration, the air vent communication path is held in a blocked state by maintaining the hydraulic pressure acting on the valve member even after the valve member is switched to the blocking position. Can do. Thereby, it is possible to suppress the hydraulic oil in the retarded hydraulic chamber or the advanced hydraulic chamber from flowing out to the other through the air vent communication passage.

  Here, if the urging force of the urging member is constant, the timing at which the valve member switches from the conducting position to the blocking position is delayed as the flow path cross-sectional area of the small-diameter passage increases, and the timing decreases as the flow cross-sectional area decreases. Becomes early. Further, if the cross-sectional area of the small-diameter passage is constant, the timing at which the valve member switches from the conducting position to the blocking position is delayed as the urging force of the urging member is increased, and the timing is earlier as the urging force is decreased. .

  Therefore, in the present invention, the flow path cross-sectional area of the small diameter passage is maintained so that the pressing force acting on the valve member is less than the urging force of the urging member while the air is being discharged through the small diameter passage. It may be set so that the pressing force is kept higher than the urging force after the air discharge is completed. According to this, by adjusting the cross-sectional area of the small-diameter passage and the urging force of the urging member, it is ensured that the air that has flowed into the retarded hydraulic chamber or the advanced hydraulic chamber is almost completely discharged at the timing. The extraction communication path can be blocked. Even when the cross-sectional area of the small-diameter passage is the same, if the air viscosity or the hydraulic oil viscosity is different, it may affect the pressing force acting on the valve member. It is more preferable to set the channel cross-sectional area of the small-diameter passage in consideration of the above.

In the present invention, the small diameter passage may allow only a fluid having a viscosity lower than a predetermined value to flow therethrough. Here, the predetermined value may be higher than the viscosity of the air staying in the valve mechanism oil path and lower than the viscosity of the hydraulic oil. According to this, air can be allowed to flow through the small-diameter passage, and the working oil can be reliably prohibited from flowing. Therefore, according to the present invention, the air vent communication passage can be reliably shut off at a suitable timing.

  Moreover, the viscosity of air and the viscosity of hydraulic fluid change with the temperature. Therefore, the above predetermined value is higher than the viscosity of air at the time of cold start of the engine, and the hydraulic oil at the time when the temperature is raised by heat received from the constituent members of the internal combustion engine (for example, the valve system, piston, etc.). It is more suitable that it is below the viscosity.

  According to this, it is possible to smoothly circulate the small-diameter passage even at the cold start when the viscosity of the air is likely to be high, and to reliably hold the valve member at the conduction position. Accordingly, it is possible to reliably prevent the air vent communication path from being blocked while air is being discharged from the retard hydraulic chamber or the advance hydraulic chamber at the time of engine start.

  Further, even when the hydraulic oil becomes hot while the valve member is held at the shut-off position, the hydraulic oil is prevented from flowing through the small diameter passage, and the valve member does not move from the shut-off position to the conduction position again. . As a result, it is possible to reliably suppress the hydraulic oil filled in the retarded hydraulic chamber or the advanced hydraulic chamber from flowing into the other hydraulic chamber.

  The means for solving the problems in the present invention can be employed in combination as much as possible.

  In an internal combustion engine equipped with a vane type variable valve mechanism, the startability of the variable valve mechanism when the engine is started can be improved.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are intended to limit the technical scope of the invention only to those unless otherwise specified. is not.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 1 to which a variable valve mechanism according to the present embodiment is applied. In the present embodiment, the display of some components in the internal combustion engine 1 is omitted. An intake pipe 19 is connected to the combustion chamber in the cylinder 2 via an intake port 18 provided in the cylinder head 10. Inflow of intake air into the cylinder 2 is controlled by an intake valve 5. A fuel injection valve 17 is provided at the intake port 18, and a spark plug 16 is provided at the top of the cylinder 2. A piston 15 connected to a crankshaft 13 as an engine output shaft of the internal combustion engine 1 via a connecting rod 14 reciprocates in the cylinder 2.

  Here, the opening / closing operation of the intake valve 5 is performed by the intake side cam 7. The intake side cam 7 is attached to the intake side camshaft 22, and an intake side pulley 24 is provided at the end of the intake side camshaft 22. Further, a variable valve mechanism 30 that can change the relative rotational phase between the intake camshaft 22 and the intake pulley 24 is provided. The variable valve mechanism 30 operates by hydraulic control based on a command signal from the ECU 29, and controls the relative rotation phase between the intake side camshaft 22 and the intake side pulley 24. That is, the valve timing of the intake valve 5 is controlled.

An exhaust pipe 21 is connected via an exhaust port 20 provided in the cylinder head 10. Exhaust exhaust to the outside of the cylinder 2 is controlled by an exhaust valve 6. The opening / closing operation of the exhaust valve 6 is performed by the exhaust side cam 8. The exhaust side cam 8 is attached to the exhaust side cam shaft 25, and an exhaust side pulley 27 is provided at the end of the exhaust side cam shaft 25. The intake pulley 24 and the exhaust pulley 27 are connected to a crank pulley (not shown) attached to the end of the crankshaft 13 by a timing belt (not shown), and the driving force of the crankshaft 13 is transmitted via the timing belt. This is transmitted to the intake side camshaft 22 and the exhaust side camshaft 25.

  In this embodiment, the intake valve 5 and the exhaust valve 6 correspond to the valves of the internal combustion engine in the present invention, and the intake side camshaft 22 and the exhaust side camshaft 25 correspond to the camshaft that drives the valves to open and close.

  The internal combustion engine 1 is provided with an electronic control unit (hereinafter referred to as “ECU”) 29 for controlling the internal combustion engine 1. The ECU 29 includes a CPU, a ROM, a RAM, and the like for storing various programs and maps to be described later, and controls the operating conditions of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's request. In addition, it is a unit that controls the valve timing of the intake valve 5 by controlling the hydraulic pressure of the variable valve mechanism 30.

  FIG. 2 is a diagram illustrating a front sectional structure of the variable valve mechanism 30 and a schematic configuration of various peripheral members of the mechanism 30 in the present embodiment. As shown in FIG. 2, the internal rotor 31 provided inside the variable valve mechanism 30 can be rotated integrally with the intake camshaft 22 by being fastened to the tip of the intake camshaft 22 with a bolt or the like. Is done. Four blade bodies (vanes) 31 a are radially formed on the outer periphery of the inner rotor 31.

  A housing 32 is provided so as to cover the outer periphery of the inner rotor 31. These housings 32 are fixed to the intake pulley 24 with bolts or the like, so that they can rotate integrally with the intake pulley 24. Note that the same number (four) of convex portions 32a as the vanes 31a of the internal rotor 31 are formed on the inner periphery of the housing 32, and each vane 31a is in a concave portion 32b formed between adjacent convex portions 32a. Is housed.

  The tip of the vane 31a is in sliding contact with the inner periphery of the recess 32b, and the tip of the protrusion 32a is in sliding contact with the outer periphery of the internal rotor 31. As a result, the internal rotor 31 and the intake side camshaft 22, the intake side pulley 24, and the housing 32 can be relatively rotated around the same axis.

  In addition, the recess 32b is partitioned into two spaces 35 and 36 by being partitioned by the vane 31a. Thereafter, of these two spaces 35 and 36, the space 35 on the rotation direction (arrow α direction) side of the intake camshaft 22 with respect to the vane 31a is the retard hydraulic chamber, and the space 36 on the opposite side is the advance hydraulic pressure. A room. The hydraulic oil is supplied to and discharged from the retard hydraulic chamber 35 and the advance hydraulic chamber 36 by a hydraulic control system described later. By changing the hydraulic pressure difference between the retard hydraulic chamber 35 and the advance hydraulic chamber 36, the balance of the forces acting on both sides of the vane 31a is changed, and the internal rotor 31 is rotated relative to the housing 32. Drive torque is generated. By this driving torque, the intake side camshaft 22 to which the internal rotor 31 is fixed and the intake side pulley 24 to which the housing 32 is fixed are relatively rotated.

Further, a through hole (accommodating hole) 37 is formed through one vane 31 a provided in the internal rotor 31 along the axial direction of the intake camshaft 22. A lock pin 38 is accommodated in the accommodation hole 37. The lock pin 38 has a function of fixing the inner rotor 31 and the housing 32 to a specific relative phase. Here, the lock pin 38 is a well-known technique and will not be described in detail. However, as a general rule, the housing 32 has an engagement hole (in which the inner rotor 31 engages with the tip of the lock pin 38 at the most retarded position). The lock pin 38 is spring-biased so as to be fitted into the engagement hole.

  When the hydraulic pressure in the retard hydraulic chamber 35 and the advance hydraulic chamber 36 is released and the internal rotor 31 shifts to the most retarded position, such as when the internal combustion engine is stopped, the lock pin 38 is fitted into the engagement hole, and the internal rotor 31 is locked in the most retarded position with respect to the housing 32. Accordingly, the position of the vane 31a is fixed even when the hydraulic pressure in the retard hydraulic chamber 35 and the advanced hydraulic chamber 36 is released. Therefore, fluctuations in the valve timing of the intake valve 5 when the engine is started are suppressed. Further, as the hydraulic pressure in the retard hydraulic chamber 35 or the advanced hydraulic chamber 36 increases, the lock pin 38 is pushed out of the engagement hole, and the vane 31a is released.

  Next, a hydraulic control system that controls the hydraulic pressure supplied to each part of the variable valve mechanism 30 will be described. FIG. 3 is a diagram showing a schematic configuration of a hydraulic control system of the variable valve mechanism 30 in the present embodiment. The oil pump 39 is mechanically driven based on the rotational force of the crankshaft 13, sucks and pumps the hydraulic oil in the oil pan 4, and supplies the hydraulic oil to the oil control valve (OCV) 40 through the oil supply passage L1. To do.

  The OCV 40 employs a 5-port type electromagnetically driven valve. As shown in the drawing, each port of the OCV 40 has an oil supply passage L1, a drain oil passage L2 for collecting the hydraulic oil in the oil pan 4, a retard oil passage L3 connected to the retard hydraulic chamber 35 of the variable valve mechanism 30, The advance oil passage L4 connected to the advance oil pressure chamber 36 is connected.

  Inside the OCV 40, there are disposed a spool 40a disposed so as to be slidable back and forth, and a spring 40b for urging the spool 40a in the left direction in the drawing. Furthermore, the OCV 40 is provided with an electromagnetic solenoid 40c that generates an electromagnetic force that attracts the spool 40a against the biasing force of the spring 40b in response to the application of a voltage. The OCV 40 is connected to the ECU 29 via electrical wiring, and the voltage applied to the electromagnetic solenoid 40c is controlled based on a control signal from the ECU 29. Thereby, the magnitude of the electromagnetic force generated by the electromagnetic solenoid 40c is controlled.

  Here, the position of the spool 40a inside the OCV 40 is determined according to the balance between the biasing force of the spring 40b and the electromagnetic force of the electromagnetic solenoid 40c. That is, the displacement state of the spool 40a changes the connection state between the ports within the OCV 40, that is, the connection state of the oil passages. More specifically, the retarded oil passage L3 connected to the retarded hydraulic chamber 35 of the variable valve mechanism 30 is connected to either the oil supply passage L1 or the drain oil passage L2 according to the displacement of the spool 40a. When the retard oil passage L3 and the oil supply passage L1 are connected, the hydraulic oil is supplied to the retard hydraulic chamber 35 to increase the internal hydraulic pressure, and the retard oil passage L3 and the drain oil passage L2 are connected. Then, the hydraulic oil is discharged from the retarded hydraulic chamber 35 and the internal hydraulic pressure is lowered.

  Further, the advance oil passage L4 connected to the advance oil pressure chamber 36 of the variable valve mechanism 30 is connected to either the oil supply passage L1 or the drain oil passage L2 according to the displacement of the spool 40a. When the advance oil passage L4 and the oil supply passage L1 are connected, the hydraulic oil is supplied to the advance oil pressure chamber 36 to increase the internal hydraulic pressure, and the advance oil passage L4 and the drain oil passage L2 are connected. Then, the hydraulic oil is discharged from the advance hydraulic chamber 36 and the internal hydraulic pressure is reduced.

  When the hydraulic pressure in the retarded hydraulic chamber 35 is higher than the hydraulic pressure in the advanced hydraulic chamber 36, the internal rotor 31 is in a direction opposite to the rotation direction of the intake camshaft 22 (arrow α direction) with respect to the housing 32. Therefore, the valve timing of the intake valve 5 is changed to the retard side. On the other hand, when the hydraulic pressure in the retard hydraulic chamber 35 is lower than the hydraulic pressure in the advance hydraulic chamber 36, the internal rotor 31 rotates relative to the housing 32 in the rotation direction of the intake camshaft 22 (arrow α direction). Therefore, the valve timing of the intake valve 5 is changed to the advance side.

  Further, when the displacement of the spool 40a is in the neutral position as shown in the drawing, all of the oil supply passage L1, the drain oil passage L2, the retard oil passage L3, and the advance oil passage L4 are blocked, so the retard hydraulic chamber 35 The hydraulic pressure inside and the advance hydraulic chamber 36 is maintained. For example, when the hydraulic pressure in the retard hydraulic chamber 35 and the advanced hydraulic chamber 36 are equal, the valve timing of the intake valve 5 is maintained.

  By adjusting the displacement of the spool 40a as described above, the communication amount (flow passage cross-sectional area) between the connected oil passages is changed, and the hydraulic oil supply flow rate in the retard hydraulic chamber 35 and the advance hydraulic chamber 36 is changed. And the discharge flow rate is adjusted. As a result, the variable valve mechanism 30 is controlled, and the valve timing of the intake valve 5 can be adjusted.

  By the way, when the engine stops, such as when the ignition of the internal combustion engine 1 is turned off, the hydraulic pressure in the retard hydraulic chamber 35 and the advanced hydraulic chamber 36 is released by the ECU 29. That is, the hydraulic oil in the retard hydraulic chamber 35 and the advance hydraulic chamber 36 is collected in the oil pan 4. Here, a force is applied to the internal rotor 31 to prevent its rotation by friction of a valve spring (not shown) of the intake valve 5. As a result, the internal rotor 31 rotates relative to the housing 32 in the retarded direction, and the internal rotor 31 is locked to the housing 32 by the lock pin 38.

  On the other hand, when the internal combustion engine 1 is started, hydraulic control related to the variable valve mechanism 30 is performed in order to adapt the valve timing of the intake valve 5 to the operating state of the internal combustion engine 1. However, since the hydraulic pressure in the retard hydraulic chamber 35 and the advance hydraulic chamber 36 is released when the engine is stopped, air accumulates in the oil supply passage L1, the retard oil passage L3, and the advance oil passage L4. In some cases, air stays inside the retarded hydraulic chamber 35 or the advanced hydraulic chamber 36.

  Accordingly, when hydraulic fluid is supplied to the retarded hydraulic chamber 35 or the advanced hydraulic chamber 36 to operate the variable valve mechanism 30 immediately after the engine is started, the air accumulated in the oil passage is pushed out to the hydraulic fluid. As a result, it flows into the retarded hydraulic chamber 35 and the advanced hydraulic chamber 36. As a result, the hydraulic oil filling time for the retarded hydraulic chamber 35 or the advanced hydraulic chamber 36 becomes longer, and the timing for starting the variable valve mechanism 30 may be delayed. As a result, the startability of the variable valve mechanism 30 at the time of engine start may deteriorate, and the emission and drivability may deteriorate.

  Therefore, in order to suppress the above problems, the variable valve mechanism 30 according to the present embodiment supplies hydraulic oil to one of the retarded hydraulic chamber 35 or the advanced hydraulic chamber 36 when the internal combustion engine 1 is started, The air flowing into the hydraulic chamber to which hydraulic fluid is supplied or the air staying in the hydraulic chamber to which hydraulic fluid is supplied is discharged to the other hydraulic chamber (this control is hereinafter referred to as “ Also referred to as “air discharge control at start-up”.

  Referring now to FIG. 2, in the variable valve mechanism 30 in the present embodiment, a bypass oil passage L5 that communicates the retard hydraulic chamber 35 and the advance hydraulic chamber 36 is provided inside each vane 31a. A valve mechanism 50 capable of switching between conduction and blocking of the bypass oil passage L5 is provided in the middle of the bypass oil passage L5 in each vane 31a, and the bypass oil passage L5 is retarded by the valve mechanism 50. It is divided into a retard side bypass oil passage L5a on the 35 side and an advance side bypass oil passage L5b on the advance hydraulic chamber 36 side. In this embodiment, the bypass oil passage L5 corresponds to the air vent communication passage in the present invention.

Hereinafter, the configuration and operation of the valve mechanism 50 will be described in detail with reference to FIGS. Here, FIG. 4 is a diagram showing a partial cross-sectional structure near the valve mechanism 50 in the present embodiment. The valve mechanism 50 in this embodiment employs a 2-port spool valve. A storage chamber 51 having a substantially cylindrical shape for storing the main components of the valve mechanism 50 is formed in the vane 31a, and a retard side communication passage L5a and an advance side communication channel are formed on the outer periphery of the storage chamber 51. A passage L5b is connected. The storage chamber 51 is formed in a cylindrical shape having a central axis substantially orthogonal to the axis of the bypass oil passage L5.

  Inside the storage chamber 51, a second spool 52 is disposed as a valve member that is disposed so as to be slidable on the inner peripheral surface of the storage chamber 51. Further, a second spring 53 as a biasing member is disposed on one inner bottom of the storage chamber 51, and biases one end of the second spool 52 in one of the reciprocating directions. Further, one end of a spool oil supply path L6 to which hydraulic oil for pressing the second spool 52 in the other direction in the reciprocating direction is supplied is connected to the other inner bottom portion of the storage chamber 51. Further, the other end of the spool oil supply passage L6 is connected between the oil pump 39 and the OCV 40 in the oil supply passage L1, as shown in FIG. Thereby, when the internal combustion engine 1 is started and the oil pump 39 is driven, the hydraulic oil is supplied to the valve mechanism 50 through the oil supply passage L1 and the spool oil supply passage L6.

  Here, the position of the second spool 52 inside the storage chamber 51 is determined according to the balance between the pressing force Pp acting on the second spool 52 and the urging force Ps of the second spring 53. Specifically, when the pressing force Pp is equal to or less than the urging force Ps, the second spool 52 comes into contact with the other inner bottom portion in the storage chamber 51 as illustrated. In this case, the retard side bypass oil passage L5a and the advance side bypass oil passage L5b are not blocked by the second spool 52. That is, the retard side bypass oil passage L5a and the advance side bypass oil passage L5b are conducted. The position of the second spool 52 at this time is referred to as a “conduction position”. In this embodiment, the conduction position corresponds to the conduction position in the present invention.

  On the other hand, when the pressing force Pp becomes higher than the urging force Ps, the second spool 52 moves in a direction away from the inner bottom portion of the storage chamber 51 against the urging force Ps. As a result, the flow paths of the retard side bypass oil passage L5a and the advance side bypass oil passage L5b are blocked by the second spool 52. The position of the second spool 52 at this time is referred to as a “cut-off position”. In this embodiment, the cutoff position corresponds to the cutoff position in the present invention.

  Further, the second spool 52 in this embodiment is electrically connected to the spool oil supply passage L6, the retard side bypass oil passage L5a, and the advance side bypass oil passage L5b when the second spool 52 is held at the conduction position. A small-diameter air discharge hole 55 is formed. A detailed description of the air discharge hole 55 will be described later. In this embodiment, the air discharge hole 55 corresponds to a small diameter passage in the present invention.

  Next, start-up air discharge control for the variable valve mechanism 30 in this embodiment will be described. Here, a case where hydraulic oil is supplied to the retarded hydraulic chamber 35 when the internal combustion engine 1 is started will be described as an example. In this embodiment, when the ignition of the internal combustion engine 1 is turned on, the oil pump 39 is driven by the rotational force of the crankshaft 13, and the hydraulic oil stored in the oil pan 4 is supplied to the OCV 40 via the oil supply passage L1. Supplied. Here, the ECU 29 issues a command to the OCV 40, and controls the displacement of the spool 40a so that the oil supply passage L1 is connected to the retard oil passage L3 and the drain oil passage L2 is connected to the advance oil passage L4. To do. Then, the air staying in the retarded oil passage L3 flows into the retarded hydraulic chamber 35 by the hydraulic oil flowing through the retarded oil passage L3.

In this embodiment, the air staying in the retarded hydraulic chamber 35 and the air flowing into the retarded hydraulic chamber 35 are discharged to the advanced hydraulic chamber 36 by the bypass oil passage L5, and then the advanced oil passage L4. And finally drain into the oil pan. More specifically, the air in the retarded hydraulic chamber 35 flows into the retarded-side bypass oil passage L5a. Here, the position of the second spool 52 is the second spring 5.
3 is held in the “conduction position” by the urging force Ps 3, the air flowing through the retard side bypass oil passage L5a flows in the order of the accommodation chamber 51 and the advance side bypass oil passage L5b, and the advance hydraulic chamber 36 is discharged. Since the advance oil passage L4 is connected to the drain oil passage L2, the air in the advance oil pressure chamber 36 is discharged to the oil pan 4 through the advance oil passage L4 and the drain oil passage L2.

  On the other hand, in this embodiment, the hydraulic oil is also supplied to the valve mechanism 50 from the spool oil supply passage L6. Here, air stays in the spool oil supply passage L6 as in the case of the retard oil passage L3. In view of this, the flow passage cross-sectional area of the air discharge hole 55 in the present embodiment is formed to such an extent that air with low viscosity can be smoothly circulated. Thus, the air flowing from the spool oil supply passage L6 flows through the air discharge hole 55 and the advance side bypass oil passage L5b and is discharged to the advance angle hydraulic chamber 36. Here, if the pressing force resulting from the air pressure acting on the second spool 52 is referred to as an air pressing force Ppa, the air pressing force Ppa acting on the second spool 52 is discharged through the air discharge hole 55. Is kept small.

  When the discharge of the air staying in the spool oil supply passage L6 through the air discharge hole 55 is completed, the hydraulic oil flows from the spool oil supply passage L6, so that the hydraulic pressure is applied to the second spool 52. Comes to work. Here, the flow passage cross-sectional area of the air discharge hole 55 is set to a size that makes it difficult for hydraulic oil with high viscosity to flow. According to this, even if the hydraulic oil tries to flow through the air discharge hole 55, the pressure loss becomes very large, so that a large hydraulic pressure acts on the second spool 52. That is, when the pressing force resulting from the hydraulic pressure acting on the second spool 52 is referred to as an oil pressing force Ppo, the oil pressing force Ppo can be increased compared to the air pressing force Ppa.

  As described above, in this embodiment, paying attention to the difference between the viscosity of air and the viscosity of hydraulic oil, the air pressing force Ppa is maintained below the biasing force Ps of the second spring 53, and the oil pressing force Ppo is biased. The flow passage cross-sectional area of the air discharge hole 55 is set to be larger than Ps. According to this, while the air is being discharged through the air discharge hole 55, the second spool 52 is held at the conduction position, whereby the bypass oil passage L5 is held in the conduction state. After the air discharge through the air discharge hole 55 is completed, the bypass spool L5 is blocked by the second spool 52 moving to the blocking position.

Here, the timing at which the discharge of air through the air discharge hole 55 ends, that is, the timing at which the pressing force Pp acting on the second spool 52 is switched from the air pressing force Ppa to the oil pressing force Ppo is from the retard hydraulic chamber 35. This generally corresponds to the timing when the discharge of air through the bypass oil passage L5 ends. In the present embodiment, the timing at which the pressing force Pp is switched and the timing at which the discharge of air from the retarded hydraulic chamber 35 through the bypass oil passage L5 substantially coincides with each other via the spool oil supply passage L6. Therefore, hydraulic oil is supplied to the valve mechanism 50.

  Specifically, for example, the amount of air staying in the retarded oil passage L3 when the engine is stopped is obtained in advance from the oil path length of the retarded oil passage L3 or the flow passage cross-sectional area, The oil path length of the spool oil supply path L6 and the flow path cross-sectional area may be determined according to the air retention amount.

  As described above, according to the start-up air discharge control of this embodiment, the second spool 52 is held in the conduction position before the discharge of air from the retarded hydraulic chamber 35 through the bypass oil passage L5 is completed. Therefore, substantially all the air that has flowed into the retarded hydraulic chamber 35 can be suitably discharged.

When the discharge of air through the bypass oil passage L5 is completed, the second spool 52 is switched to the shut-off position, and the second spool 52 is held at the shut-off position by continuous supply of hydraulic oil from the spool oil feed passage L6. Is done. As a result, it is possible to suppress the hydraulic oil supplied to the retarded hydraulic chamber 35 from flowing out to the advanced hydraulic pressure 36 via the bypass oil passage L5, and to quickly fill the retarded hydraulic chamber 35 with the hydraulic oil. it can.

  As a result, the start of the variable valve mechanism 30 can be started early, and the startability of the variable valve mechanism 30 when the engine is started can be improved. That is, the valve timing of the intake valve 5 can be adapted to the operating state of the internal combustion engine 1 immediately after the engine is started, and exhaust emission and drivability can be improved.

  Note that the air discharge hole 55 in the present embodiment may be formed so that only a fluid whose viscosity is lower than the reference viscosity can flow. This reference viscosity is a value that is higher than the viscosity of the air staying in the spool oil supply passage L6 and less than the viscosity of the hydraulic oil supplied through the spool oil supply passage L6. In this case, the reference viscosity corresponds to the predetermined value in the present invention. According to this, since air can be reliably circulated and hydraulic oil can be reliably circulated, switching between conduction and interruption of the bypass oil passage L5 can be performed easily and reliably.

  Furthermore, the viscosity of air and hydraulic oil changes with the temperature. Accordingly, the air discharge hole 55 allows air to flow even when the internal combustion engine 1 is cold-started, and the flow of the hydraulic oil whose viscosity has been lowered by the heat received by the piston 15 or the like cannot flow. It is more preferable to set the road cross-sectional area.

  According to this, air can be smoothly circulated through the air discharge hole 55 and the second spool 52 can be reliably held at the conduction position even during cold start when the viscosity of the air tends to increase. And even if hydraulic fluid becomes high temperature while holding the 2nd spool 52 in the interruption | blocking position, it can suppress reliably that the 2nd spool 52 moves to a conduction | electrical_connection position again from the interruption | blocking position.

  Further, the start-up air discharge control of the present embodiment has been described as an example in which the hydraulic oil is supplied to the retard hydraulic chamber 35, but may be applied when the hydraulic oil is supplied to the advance hydraulic chamber 36. Of course it is good. In that case, since the air retained in the advance oil passage L4 is supplied to the advance oil pressure chamber 36 prior to the hydraulic oil, after being discharged to the retard oil pressure chamber 35 via the bypass oil passage L5, Further, it may be discharged to the oil pan 4 through the retarded oil passage L3.

  In the present embodiment, the case where the variable valve mechanism according to the present invention is applied to the intake valve 5 has been described, but it goes without saying that the variable valve mechanism may be applied to the exhaust valve 6. The spool oil supply passage L6 for supplying the hydraulic oil supplied to the valve mechanism 50 is branched from the middle of the oil supply passage L1, and a spool valve is adopted for the valve mechanism 50. It is an example for description, and various modifications can be made without departing from the spirit of the present invention.

1 is a diagram illustrating a schematic configuration of an internal combustion engine to which a variable valve mechanism according to a first embodiment is applied. It is a figure which shows schematic structure of the front sectional structure of the variable valve mechanism in Example 1, and the various peripheral members of the mechanism. It is a figure which shows schematic structure of the hydraulic control system of the variable valve mechanism in Example 1. FIG. It is a figure which shows the partial cross section structure of the valve mechanism vicinity in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 4 ... Oil pan 5 ... Intake valve 6 ... Exhaust valve 13 ... Crankshaft 22 ... Intake side camshaft 29 ... ECU
30..Variable valve mechanism 31..Internal rotor 31a.Vane 32..Housing 31b.Recess 35..Delay hydraulic chamber 36..Advanced hydraulic chamber 40..Oil control valve L1..Oil supply path L2. Drain oil passage L3, ... retard oil passage L4, advance oil passage L5, bypass oil passage L6, spool oil supply passage 50, valve mechanism 51, storage chamber 52, second spool 53, second Spring 55 ・ Air discharge hole

Claims (4)

A housing connected to one of the output shaft of the internal combustion engine or at least one of the intake valve and the exhaust valve of the internal combustion engine and having a recess therein, and the other of the output shaft and the cam shaft And an internal rotor having a vane that is rotatably arranged in the housing and partitions the recess into a retarded hydraulic chamber and an advanced hydraulic chamber, and at least the retarded hydraulic chamber or the advanced angle Supplying / exhausting hydraulic oil to / from one of the hydraulic chambers, changing the relative magnitude of the hydraulic pressure applied to the vanes from the retard hydraulic chamber and the advance hydraulic chamber, and changing the internal rotor to the housing In a variable valve mechanism for an internal combustion engine that changes the opening and closing timing of the valve by relative rotation,
An air vent communication passage that is formed in the vane and communicates with the retard hydraulic chamber and the advance hydraulic chamber, and discharges air that flows into one of the retard hydraulic chamber or the advance hydraulic chamber to the other;
A valve mechanism that shuts off the air vent communication passage at a timing when the discharge of air through the air vent communication passage is substantially completed;
A variable valve mechanism for an internal combustion engine, further comprising: The valve mechanism is
A storage chamber formed in the vane to which the air vent communication passage is connected, and a conduction position that is slidably reciprocated in the storage chamber and conducts the flow path of the air vent communication passage, and a blocking position that shuts off the passage. And a biasing member that biases the valve member in one of the reciprocating directions to hold the valve member in the conduction position.
An oil path for a valve mechanism that is supplied with hydraulic oil for pressing the valve member in the other direction in the reciprocating direction and holding the valve member in a blocking position against the urging force of the urging member. Is connected,
The valve member is formed with a small-diameter passage that electrically connects the valve mechanism oil passage and the air vent communication passage when the valve member is held at least in the conduction position.
The valve mechanism so that the timing at which the discharge of air through the air vent communication passage ends and the timing at which the discharge of the air staying in the oil passage for the valve mechanism through the small diameter passage ends substantially coincide. The variable valve mechanism for an internal combustion engine according to claim 1, wherein hydraulic oil is supplied to the valve mechanism from an oil passage.   The cross-sectional area of the small-diameter passage is such that the pressing force acting on the valve member is maintained below the urging force of the urging member while air is being discharged through the small-diameter passage, The variable valve mechanism for an internal combustion engine according to claim 2, wherein the pressing force is set to be higher than the urging force after the discharge is finished.   4. The variable valve mechanism for an internal combustion engine according to claim 2, wherein only the fluid whose viscosity is lower than a predetermined value can flow through the small diameter passage.

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