JP3424306B2 - Variable valve train for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake valve or an exhaust valve of an internal combustion engine (hereinafter, both are collectively referred to as intake and exhaust valves).
The present invention relates to a variable valve operating device for an internal combustion engine that variably controls the lift amount of the engine.

[0002]

2. Description of the Related Art A hydraulic variable valve operating device for variably controlling the lift amount of intake and exhaust valves of an internal combustion engine is disclosed in, for example, Japanese Patent Laid-Open No. 58-5.
It is disclosed in Japanese Patent No. 3615. This device pressurizes the hydraulic oil along the cam lift by reciprocating the cam side plunger by the cam shaft, and hydraulically drives the intake / exhaust valve by the pressurized hydraulic oil. A release valve that releases the pressurized hydraulic oil to the low pressure side is provided in the hydraulic oil supply path. When the release valve is opened during the lift of the intake / exhaust valve, the pressure of the hydraulic oil decreases, so that the intake / exhaust valve is switched to the seating operation from the middle of the lift by the urging force of the valve spring. That is, the lift amount of the intake / exhaust valve can be variably controlled by the opening timing of the release valve.

A structure in which hydraulic energy released by the release valve is absorbed by an accumulator to recover hydraulic energy is shown in, for example, SAE paper 930820. FIG. 4 shows the configuration of this conventional variable valve operating device. A cam side plunger 40 driven by a cam 43 pressurizes the hydraulic oil in a hydraulic chamber 41, and the pressurized hydraulic oil causes the valve side plunger 40 to move. The intake / exhaust valve 45 is lifted via 44. The hydraulic chamber 41 and the accumulator 48 are connected via a hydraulic pressure release passage 49, and the release valve 4 is connected to the hydraulic pressure release passage 49.
6 is interposed. The release valve 46 is opened by a pressure balance between the hydraulic chamber 41 and the back pressure chamber 46a, and a pilot valve 47, which is an electromagnetic valve, is provided to release the hydraulic pressure in the back pressure chamber 46a. Further, the accumulator 48 and the hydraulic chamber 41 are connected in parallel to the hydraulic pressure release passage 49 via a hydraulic pressure introducing passage 50, and the hydraulic introducing passage 50 is provided with a reverse flow that allows only the inflow from the accumulator 48 to the hydraulic chamber 41. A stop valve 51 is provided. Further, hydraulic oil is supplied to the accumulator 48 from the oil pump 52 via the check valve 53. In such a configuration, the high-pressure hydraulic oil discharged via the release valve 46 is introduced into the accumulator 48, and thereafter, when the lift amount of the cam 43 decreases,
It is fed back from the accumulator 48 to the hydraulic chamber 41 via the hydraulic pressure introducing passage 50. Therefore, the energy once collected by the accumulator 48 is added to the driving force of the cam 43, and the energy can be effectively used as a whole.

[0004]

However, in such a conventional structure, when the hydraulic oil reciprocates between the accumulator 48 and the hydraulic chamber 41, it passes through the release valve 46 and the check valve 51. Energy loss due to passage resistance occurs and the energy recovered is reduced. In order to reduce such energy loss, the release valve 4
6 and the opening area of the check valve 51 need to be set large, but this is not preferable in terms of weight reduction and installation space of the device as the release valve 46 and the check valve 51 increase in size.

Further, in order to reduce the above-mentioned energy loss, Japanese Patent Laid-Open No. 1-315605 discloses a structure in which a check valve is omitted by integrating a solenoid valve serving as a release valve and an accumulator. However, if the solenoid valve and accumulator are integrated in this way, the structure of the solenoid valve becomes large and complicated, and large parts including the accumulator will be driven by the magnetic force of the solenoid. There is a drawback that the responsiveness, which is important in control, deteriorates.

An object of the present invention is to eliminate the check valve between the accumulator and the hydraulic chamber without complicating the structure and deteriorating the responsiveness, and to reduce energy loss.

[0007]

A variable valve operating system for an internal combustion engine according to the present invention is an intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring and a camshaft to drive the valve. A cam side plunger that pressurizes the hydraulic oil, a valve side plunger that moves to one side by the hydraulic pressure in the pressurized hydraulic chamber and lifts the intake valve or the exhaust valve, and a slidable piston define an accumulator chamber. an accumulator to comprising, by connecting the hydraulic chamber and the accumulator chamber, above the said hydraulic chamber
The pilot pressure passage for introducing the pilot pressure into the accumulator chamber and the accumulator are configured separately.
And a pilot valve that opens and closes the pilot pressure passage,
An accumulator configured to urge the piston of the accumulator in the direction of contraction of the accumulator chamber and to have the urging force set so that the piston is displaced by the hydraulic pressure introduced from the hydraulic chamber to the accumulator chamber via the pilot valve. A spring and a hydraulic pressure release passage that opens when the piston of the accumulator is displaced and connects the hydraulic chamber and the accumulator chamber are provided.

According to the second aspect of the invention, the piston or casing of the accumulator is provided with a seal member for preventing leakage of hydraulic oil from the hydraulic pressure release passage to the accumulator chamber when the piston is in the non-displacement position.

Further, according to the invention of claim 3, a drain passage having an orifice is connected to the accumulator chamber.

Further, in the invention of claim 4, the pilot valve comprises an electromagnetic valve which opens and closes depending on whether or not the power is supplied, and in the closed state, the valve body does not receive the hydraulic pressure from the hydraulic chamber in the valve opening direction. Is configured.

Further, in the invention of claim 5, the pilot valve has a valve body which receives the hydraulic pressure from the hydraulic chamber in a valve opening direction, and the hydraulic pressure in the hydraulic chamber reaches a hydraulic pressure corresponding to a desired valve lift amount. Sometimes the valve body lifts,
The solenoid relief valve includes a solenoid that variably applies a pressing force to the valve body in the valve closing direction.

[0012]

When the cam shaft presses the cam side plunger, the hydraulic pressure in the hydraulic chamber increases, and the valve side plunger moves accordingly. In other words, the intake / exhaust valve lifts in a form corresponding to the hydraulic pressure. When the pilot valve opens during this lift, the pressure in the accumulator chamber rises and the piston displaces. As a result, the pressure in the hydraulic chamber is released to the accumulator chamber in the low pressure state, so that the intake / exhaust valve turns to the seating operation during the lift. Therefore, the lift amount changes by changing the valve opening timing of the pilot valve.

The high-pressure hydraulic fluid flowing into the accumulator chamber displaces the accumulator spring and accumulates pressure in the accumulator. Therefore, when the lift of the cam decreases thereafter, the hydraulic oil flows from the accumulator chamber into the hydraulic chamber. Pushed back. This makes it possible to recover energy. When the piston of the accumulator is displaced, the hydraulic release passage communicates with the accumulator chamber with a sufficiently large passage opening area, and there is no check valve in the passage, so the hydraulic chamber and the accumulator chamber are not connected. energy loss due to the reciprocating of the hydraulic oil between the small.

According to the second aspect of the invention, when the piston is at the non-displacement position, that is, when the intake / exhaust valve is lifted, leakage of hydraulic oil from the hydraulic pressure release passage is prevented,
It is possible to prevent abnormal operation of the accumulator due to a rise in pressure in the accumulator chamber.

According to the third aspect of the present invention, the accumulator chamber is reliably kept in the low pressure state when the pilot valve is closed.

When the pilot valve is a solenoid valve as in claim 4, the energization is turned on and off from the outside.
Control is performed to control the operation of the piston of the accumulator that functions as a release valve. In particular, by configuring the valve body so that the hydraulic pressure does not act in the valve opening direction, the valve opening due to surge pressure in the hydraulic chamber at the initial stage of the cam lift is prevented.

On the other hand, according to the fifth aspect of the invention, the pilot valve is opened by the hydraulic pressure itself in the hydraulic chamber.
That is, when the hydraulic pressure of the hydraulic oil increases with the lift of the intake / exhaust valve, the pressing force that acts on the valve body of the pilot valve in the valve opening direction also increases. When the pressing force in the valve closing direction that is variably set by the solenoid exceeds the pressing force in the valve opening direction due to the hydraulic pressure, the valve body lifts and supplies the hydraulic pressure to the accumulator chamber. Along with this, the piston of the accumulator is displaced, and the hydraulic pressure releasing operation is performed as described above. Therefore, if the pressing force of the solenoid is changed, the opening timing of the pilot valve changes, that is, the lift amount of the intake / exhaust valve changes.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an essential part of an internal combustion engine showing a first embodiment of the present invention. An intake / exhaust valve 2 is slidably mounted on a cylinder head 1 and a valve spring 3 is used. Always biased in the closing direction. A housing 4 of the lift control unit is superposed on the upper surface of the cylinder head 1, and a valve side plunger 6 is slidably fitted in a cylinder hole 5 formed in the lower surface of the housing 4. . The tip of this valve side plunger 6 is
The intake / exhaust valve 2 is pushed open by contacting the stem end of the intake / exhaust valve 2 and moving the plunger 6 by hydraulic pressure.

A cam side plunger 7 is slidably arranged in a cylinder hole 8 on the upper surface of the housing 4. The cam side plunger 7 and the valve side plunger 6
Share the main hydraulic chamber 9 as a hydraulic chamber. That is,
The cam side plunger 7 is a cam 10a of a cam shaft 10 that rotates in synchronization with a crankshaft (not shown) of the internal combustion engine.
Further, it is driven via the rocker arm 11, and reciprocates when the cam shaft 10 rotates to pressurize the hydraulic oil in the main hydraulic chamber 9. The valve side plunger 6 is pressed by the hydraulic pressure in the lift direction of the intake / exhaust valve 2.

The working oil is supplied to the main hydraulic chamber 9 through a working oil supply passage 12 having a check valve 13. The working oil supply passage 12 has a working oil introduction hole. It communicates with the discharge side of an oil pump (not shown) via 14. This hydraulic oil supply system is integrated with the engine lubricating system, and the engine lubricating oil is used as the hydraulic oil, and the lubricating oil pump mechanically driven by the engine output is also used as it is.

The housing 4 has an intake / exhaust valve 2
In order to variably control the lift amount of
An accumulator 16 that functions as a release valve and a pilot valve 17 that supplies pilot pressure to the accumulator 16 are provided.

The accumulator 16 is a piston 1 slidably arranged in an accumulator casing 19.
8 and the piston 18 defines an accumulator chamber 21. The piston 18 is biased by an accumulator spring 20 in a direction in which the accumulator chamber 21 contracts. The back pressure chamber 22 accommodating the accumulator spring 20 is open to the atmosphere via a communication hole 23.

The accumulator 16 has a main hydraulic chamber 9
To the hydraulic pressure release passage 24. The tip of the hydraulic pressure release passage 24 opens toward the outer peripheral surface of the piston 18, and is closed by the piston 18 when the piston 18 is not displaced and the piston 18
When is displaced, it communicates with the accumulator chamber 21. The piston 18 has a taper portion 18a on the side of the accumulator chamber 21 and receives the biasing force of the accumulator spring 20 to press the taper portion 18a against the taper surface of the accumulator casing 19 to close the hydraulic pressure release passage 24. The time is sealed.

A drain passage 26 having an orifice 25 is connected to the accumulator chamber 21.
The accumulator chamber 21 is opened to the oil pan 27 via the drain passage 26. The tip 26a of the drain passage 26 extends to the bottom of the oil pan 27,
There is no intake of air. Therefore, for example, even if the hydraulic oil slightly leaks from the hydraulic pressure release passage 24 through the contact surface between the piston 18 and the accumulator casing 19, the inside of the accumulator chamber 21 is reliably kept at a low pressure state.

On the other hand, in this embodiment, the pilot valve 17 is an ON / OFF type solenoid valve which opens and closes depending on the presence or absence of energization. That is, the pilot valve 17 is a needle-shaped valve body 2 slidably supported.
9, the valve body 29 is constantly urged in the valve closing direction by the spring 28, and the valve body 29 is opened in the valve opening direction.
A solenoid 30 is provided to urge the solenoid. The pilot valve 17 opens and closes a pilot pressure passage 31 that connects the main hydraulic chamber 9 and the accumulator chamber 21. In particular, in order to prevent the high hydraulic pressure from the main hydraulic chamber 9 from acting on the valve element 29 in the valve opening direction, the portion of the pilot pressure passage 31 on the main hydraulic chamber 9 side is opened toward the side surface of the valve element 29. Also, the accumulator chamber 21 side portion is the valve body 29.
It opens toward the tip. Therefore, even if a high surge pressure occurs in the main hydraulic chamber 9 when the cam lift rises, the pilot valve 17 will not open due to the influence of the surge pressure.

The valve body 29 receives a pressing force in the valve opening direction due to the hydraulic pressure in the accumulator chamber 21, and is pressed in the seating direction by the urging force of the spring 28 so as to oppose the pressing force. The biasing force of this spring 28 is
It is set to always exceed the pressing force in the lift direction by the hydraulic pressure of the accumulator chamber 21, and the solenoid 30
When the energization is stopped, the valve element 29 is securely held in the seated state. When the solenoid 30 is energized, the valve body 29 is attracted in the lift direction by the magnetic force, and the valve body 29 is lifted by exceeding the biasing force of the spring 28.

Next, the operation of the above embodiment will be described. When the cam side plunger 7 is pressed along with the lift of the cam 10a, the hydraulic pressure in the main hydraulic chamber 9 rises, whereby the valve side plunger 6 moves. That is, the lift of the intake / exhaust valve 2 is started. When the solenoid 30 of the pilot valve 17 is energized while the intake / exhaust valve 2 is being lifted by the pressurized hydraulic oil in the main hydraulic chamber 9 as described above, the pilot valve 1
7 is opened, the oil pressure in the main oil pressure chamber 9 changes to the pilot pressure passage 3
1 is introduced as a pilot pressure into the accumulator chamber 21. With this pilot pressure introduced,
Since the spring force and the pressure receiving area are set so that the pressing force due to the hydraulic pressure in the accumulator chamber 21 exceeds the urging force of the accumulator spring 20, the piston 18 moves upward while pressing the accumulator spring 20. As a result, the hydraulic pressure release passage 24 is opened. That is, the tip of the hydraulic pressure release passage 24 and the accumulator chamber 21 are in communication with each other, and the hydraulic pressure in the main hydraulic chamber 9 is released to the accumulator chamber 21 in the low pressure state. Therefore, the intake / exhaust valve 2 switches to a seating operation during the lift. Here, the piston 18 has a relatively large size in order to secure a capacity necessary for the accumulator 16, so that the hydraulic pressure release passage 24 in the displaced state of the piston 18 is used.
A sufficiently large passage opening area can be secured. Therefore, the energy loss when the hydraulic oil moves from the main hydraulic chamber 9 to the accumulator chamber 21 is very small.

After that, when the lift of the cam 10a gradually decreases, the hydraulic oil stored in the accumulator chamber 21 is pushed back into the main hydraulic chamber 9 through the hydraulic pressure release passage 24. This hydraulic energy is supplied to the camshaft 10
Of energy, which results in energy recovery. In this way, when the hydraulic oil returns from the accumulator chamber 21 to the main hydraulic chamber 9, the check valve is not present in the path, so that the energy loss becomes very small.
Since a part of the hydraulic oil is discharged from the accumulator chamber 21 to the oil pan 27 via the drain passage 26, the same amount of hydraulic oil is replenished via the hydraulic oil supply passage 12.

As described above, according to the above-described embodiment, the energy loss can be made extremely small when the working oil reciprocates between the main hydraulic chamber 9 and the accumulator chamber 21, and the fuel consumption rate of the internal combustion engine is correspondingly reduced. Can be improved.
Further, the pilot valve 17 is configured separately from the accumulator 16, and only opens and closes the pilot pressure passage 31 having a relatively small passage area, so that the responsiveness does not deteriorate.

Next, FIG. 2 shows a second embodiment in which a seal member 33 is provided between the piston 18 of the accumulator 16 and the accumulator casing 19. The seal member 33 has an annular shape and serves as a seal surface for the piston 1.
It is interposed between the tapered portion 18 a of No. 8 and the tapered surface of the accumulator casing 19. Although the seal member 33 is attached to the accumulator casing 19 side in the illustrated example, it may be attached to the piston 18 side conversely.

According to the structure in which the seal member 33 is provided as described above, the hydraulic pressure release passage 24 and the accumulator chamber 21 are more reliably shut off when the piston 18 is in the non-displacement position, and the pressurized hydraulic oil Leakage is prevented. Therefore, it is possible to prevent a decrease in the hydraulic pressure of the main hydraulic chamber 9 during the lift of the intake / exhaust valve 2, and it is possible to reliably secure a desired lift amount. The seal member 33 also functions as a cushioning material when the piston 18 and the accumulator casing 19 collide with each other, and also has an effect of reducing the sound generated due to the collision.

Next, FIG. 3 shows a third embodiment in which the pilot valve 17 is a pressure balance type electromagnetic relief valve. The parts other than the pilot valve 17 have basically the same structure as those of the first and second embodiments.

The pilot valve of this embodiment includes a needle-shaped valve body 35 that opens and closes the pilot pressure passage 31, and a spring 34 that biases the valve body 35 in the valve closing direction with a relatively small biasing force. , The valve 35 depending on the current
Is also provided with a solenoid 36 for pressing in the valve closing direction. The valve element 35 blocks the pilot pressure passage 31 while seated on the valve seat.
A portion of the pilot pressure passage 31 on the main hydraulic chamber 9 side is open toward the tip of the valve body 35. That is, in the valve closed state in which the valve body 35 is seated on the valve seat, the valve body 35 does not have the main hydraulic chamber 9
The hydraulic pressure inside acts in the valve opening direction. Then, in opposition to this, the pressing force of the solenoid 36 (actually, the sum of the pressing force of the solenoid 36 and the urging force of the spring 34) acts in the valve closing direction. Since the hydraulic pressure in the main hydraulic chamber 9 and the lift amount of the intake / exhaust valve 2 have a constant correspondence relationship, the intake / exhaust valve 2 reaches a certain lift amount and reaches a predetermined hydraulic pressure value corresponding thereto within the main hydraulic chamber 9. When the pressure increases, the valve body 35 automatically opens. As a result, similarly to each of the above-described embodiments, the pilot pressure is introduced into the accumulator chamber 21 and the hydraulic pressure in the main hydraulic chamber 9 is released.

Since the magnetic force of the solenoid 36 that presses the valve element 35 in the valve closing direction is proportional to the current supplied to the solenoid 36, the current can be variably controlled so that the pilot valve 17 can be opened. The hydraulic pressure in the main hydraulic chamber 9, and thus the lift amount of the intake / exhaust valve 2, can be variably controlled.

Therefore, in the variable valve operating apparatus according to the third embodiment, the intake / exhaust valve 2 automatically starts the seating operation after being lifted by the desired amount, and the solenoid 36
There is no need to control ON and OFF for each cycle. Therefore, there is an advantage that the configuration of the control circuit becomes very simple and requirements for responsiveness of calculation and control are relaxed.

The pilot valve 17 is not limited to the electromagnetic construction as shown in each of the above embodiments as long as it can simply apply the pilot pressure to the accumulator chamber 21 in a pulsed manner.

[0038]

As is apparent from the above description, in the variable valve operating system for an internal combustion engine according to the present invention, when the hydraulic oil reciprocates between the hydraulic chamber pressurized by the cam side plunger and the accumulator chamber. The energy loss can be greatly reduced, and the fuel consumption rate can be improved. Further, since the pilot valve and the accumulator have separate configurations, the configuration is not complicated and the responsiveness is not deteriorated.

If the accumulator is provided with the seal member as in the second aspect, the leakage of the hydraulic oil from the hydraulic pressure release passage can be prevented, and the abnormal operation of the accumulator due to the pressure increase in the accumulator chamber can be prevented.

Further, by providing the drain passage as in claim 3, it is possible to prevent the pressure in the accumulator chamber from rising due to leakage of hydraulic pressure.

Furthermore, if a solenoid valve that opens and closes depending on the presence or absence of energization is used as the pilot valve as in the fourth aspect, variable control of the lift amount can be reliably performed without variation among the cylinders. Moreover, by preventing the hydraulic pressure from the hydraulic chamber from being received in the valve opening direction, it is possible to prevent a malfunction due to a surge pressure that is noticeable at a high rotation speed.

Further, when the pilot valve is constructed as the electromagnetic relief valve as in claim 5, the seating operation is automatically started when the intake / exhaust valve is lifted by a desired amount. ON from outside every cycle,
There is no need to control OFF. Therefore, the load of calculation and control in the control circuit is significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a variable valve operating device according to the present invention.

FIG. 2 is a sectional view showing a second embodiment.

FIG. 3 is a sectional view showing a third embodiment.

FIG. 4 is a structural explanatory view showing a structure of a conventional variable valve operating device.

[Explanation of symbols]

2 ... Intake and exhaust valves 6 ... Valve side plunger 7 ... Plunger on the cam side 9 ... Main hydraulic chamber 16 ... Accumulator 17 ... Pilot valve 18 ... Piston 20 ... Accumulator spring 21 ... Accumulator room 24 ... Hydraulic release passage 26 ... Drain passage 31 ... Pilot pressure passage 33 ... Seal member

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01L 13/00 301 F01L 9/02 F16K 41/42

Claims (5)

(57) [Claims] 1. An intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring, a cam side plunger which is driven by a cam shaft and pressurizes hydraulic oil in a hydraulic chamber, and the pressurized hydraulic chamber. It moves to one side by the hydraulic pressure of
A valve-side plunger that lifts the intake valve or the exhaust valve, an accumulator that defines an accumulator chamber by a slidable piston, the hydraulic chamber and the accumulator chamber are connected, and the oil
Introduce pilot pressure from the pressure chamber to the accumulator chamber.
A pilot pressure passage that is constructed separately from the above accumulator, and a pilot valve for opening and closing the pilot pressure passage, biasing the piston of the accumulator to the reduction direction of the accumulator chamber, and hydraulic pressure via the pilot valve So that the piston is displaced by the hydraulic pressure introduced into the accumulator chamber from the chamber, the accumulator spring having its urging force set, and the piston of the accumulator opened in the displaced state, the hydraulic chamber and the accumulator chamber A variable valve operating device for an internal combustion engine, comprising: a hydraulic pressure release passage that communicates with each other. 2. The piston or casing of the accumulator is provided with a seal member for preventing leakage of hydraulic oil from the hydraulic pressure release passage to the accumulator chamber when the piston is in the non-displacement position. 1. A variable valve operating device for an internal combustion engine according to 1. 3. A variable valve operating system for an internal combustion engine according to claim 1, wherein a drain passage having an orifice is connected to the accumulator chamber. 4. The pilot valve is a solenoid valve that opens and closes depending on the presence or absence of energization, and in the closed state, the valve body is configured not to receive the hydraulic pressure from the hydraulic chamber in the valve opening direction. The variable valve operating system for an internal combustion engine according to any one of claims 1 to 3, which is characterized in that. 5. The pilot valve includes: a valve body that receives a hydraulic pressure from the hydraulic chamber in a valve opening direction; and a valve body that receives a hydraulic pressure in the hydraulic chamber that corresponds to a desired valve lift amount. 2. An electromagnetic relief valve comprising: a solenoid that variably applies a pressing force to the valve body in a valve closing direction so as to lift the valve body.
4. A variable valve operating device for an internal combustion engine according to any one of 3 to 3.