JPH10231715A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine to properly vary the lift of an exhaust valve according to an operation state when the opening of an exhaust valve is controlled for an engine brake or re-circulation of exhaust gas at other than an ordinary exhaust process. SOLUTION: An internal combustion engine comprises a lifter body 17 to slide at least one of a master piston 2a (2b) and a slave piston in a state to front on oil passages 5a and 5b; a bush pin 20 retractably arranged on the opposite oil passage side of the body 17; a spring 19 disposed in a body 17 to hold the pin 20 in a given extension position; and lock mechanisms 22, 23, 24, and 25 to properly fix and release protrusion and retraction operation of the pin 20 in the extension position. By fixing and releasing protrusion and retraction operation of the pin 20, an operation stroke is variable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which an exhaust valve is opened near a compression top dead center when an engine brake is operated to release compressed air to secure a braking force, or an exhaust gas is discharged in an intake stroke. The combustion temperature is lowered by opening the valve and allowing exhaust gas to flow back into the combustion chamber, thereby reducing the combustion temperature.
The present invention relates to an internal combustion engine designed to reduce Ox (nitrogen oxide), and more particularly to an internal combustion engine having both former and latter functions.

[0002]

2. Description of the Related Art When an engine brake is operated, an exhaust valve is opened near a compression top dead center to release compressed air to release a compressed air. Japanese Patent Application No. 6-108 filed by the present applicant as an internal combustion engine that also enables circulation.
No. 406 (Japanese Patent Application Laid-Open No. 7-97959) exists, and has a configuration as shown in FIG.

[0005] In the figure, reference numeral 5 denotes an oil passage.
Solenoid valve 3 for switching between holding and releasing hydraulic pressure
And oil (engine oil) is supplied via a control valve 4. The solenoid valve 3 supplies and shuts off oil, and the control valve 4 supplies an oil supply port by the solenoid valve 3. Functions as a check valve so that the oil pressure in the oil passage 5 is maintained when the oil supply port is open, and is pushed down by a spring (not shown) when the oil supply port is closed by the solenoid valve 3 so that the oil is pressed down. It functions so as to release the hydraulic pressure in the passage 5.

A slave piston 6 is pushed down by the pressure generated in the oil passage 5 and opens an exhaust valve 8 of a cylinder 7 via an actuator pin 10.

[0005] 1a is an inlet push rod of another cylinder, and 1b is an exhaust push rod of another cylinder. 2a is the inlet push rod 1
a is a master piston for engine brakes operated by the rocker arm 19a operated by a, and 2b is a master piston for exhaust gas recirculation operated by the rocker arm 19b operated by the exhaust push rod 1b. The engine brake master piston 2a and the exhaust gas recirculation master piston 2b function to generate pressure in the oil supplied to the oil passage 5 of the cylinder 7.

Reference numeral 11 denotes an oil passage switching valve for selectively switching the hydraulic pressure generated by the engine brake master piston 2a and the exhaust gas recirculation master piston 2b to the oil passage 5. The oil passage switching valve 11 includes an oil passage 5 a on the engine brake master piston 2 a side and the oil passage 5.
12a that communicates and shuts off the oil passage, an oil passage 5b on the master piston 2b side for exhaust gas recirculation, and the oil passage 5
A spool 12b for communicating and shutting off the
2c.

A switching operation mechanism of the oil passage switching valve 11 has a spring 14 interposed at one end of the spool valve shaft 12 and electromagnetically switches to a chamber 15 formed at the other end on the top surface side of a piston portion 12c. A pressure source is connected via the valve 16 and the spool valve shaft 12 is axially moved by switching the electromagnetic switching valve 16 to open and close the oil passages 5a and 5b. 13a and 13b are discharge passages.

FIG. 7 shows an example of a related arrangement of the above-described device in an in-line six-cylinder engine.
(7) The opening control of the exhaust valve 8 is performed by the inlet push rod 1a and the exhaust push rod 1b of the second cylinder # 2, and the opening control of the exhaust valve 8 of the second cylinder # 2 is controlled by the third cylinder # 3. Inlet push rod 1a and exhaust push rod 1b are responsible,
The opening control of the exhaust valve 8 of the third cylinder # 3 is performed by the inlet push rod 1a and the exhaust push rod 1b of the first cylinder # 1 (7).

Regarding the operation of the above-mentioned device, the first cylinder # 1
An example in which the opening control of the exhaust valve 8 of (7) is performed by the inlet push rod 1a and the exhaust push rod 1b of the second cylinder # 2 will be described with reference to FIGS.

First, when the engine brake is operated, that is, while the vehicle is running, the exhaust brake switch (not shown) is on and the foot is released from the accelerator pedal, the electromagnetic switching valve 16 is switched to the chamber 15. Pressure oil is supplied, the oil passage 5b on the exhaust gas recirculation master piston 2b side is closed, and the oil passage 5a on the engine brake master piston 2a side communicates with the oil passage 5 as shown in FIG. The switching valve 11 is switched.

In this state, the operation of the master piston 2 for the engine brake through the rocker arm 19a by the operation of the inlet push rod 1a of the second cylinder # 2 during the intake stroke.
When a is pushed up, pressure is generated in the oil supplied from the rocker shaft bracket to the oil passage 5 through the solenoid valve 3 and the control valve 4, and the generated oil pressure causes the cylinder 7 in the expansion stroke to move through the slave piston 6. The exhaust valve 8 of the (first cylinder # 1) is opened, compressed air is released from the exhaust port 9 and no force is generated to push down the piston, so that the braking force obtained in the compression stroke is effectively lost. Will be used.

At the time of exhaust gas recirculation (EGR), that is, when the accelerator pedal is depressed to some extent during running and the engine is not idling and not under a high load, the electromagnetic switching valve 16 is switched and the spring 14 is turned on.
The pressure oil in the chamber 15 is discharged by the urging force, the oil passage 5a on the engine piston master piston 2a side is closed, and the oil passage 5b on the exhaust gas recirculation master piston 2b side and the oil passage 5 communicate with each other. The switching valve 11 is switched.

In this state, the exhaust gas recirculation master piston 2 is driven via the rocker arm 19b by the operation of the exhaust push rod 1b of the second cylinder # 2 in the exhaust stroke.
When b is pushed up, pressure is generated in the oil supplied from the rocker shaft bracket to the oil passage 5 through the solenoid valve 3 and the control valve 4, and the generated oil pressure causes the cylinder 7 to move through the slave piston 6 in the intake stroke. The exhaust valve 8 of the (first cylinder # 1) is opened.

At this time, since the internal pressure of the exhaust pipe of the second cylinder # 2 is high during the exhaust stroke, part of the exhaust gas of the second cylinder # 2 is transferred to the cylinder 7 (first cylinder # 1) due to the pressure difference. As a result, the combustion temperature in the combustion chamber in the next explosion stroke of the cylinder 7 (the first cylinder # 1) is reduced, and NOx (nitrogen oxide) is reduced.

If the oil supply port is closed by the solenoid valve 3, the oil passage 5 is controlled by the control valve 4.
Is released, and no pressure is generated in the oil passage 5, so that the slave piston 6 is not driven, and the exhaust valve 8 is controlled to open for engine braking or exhaust gas recirculation other than the normal exhaust stroke. No more.

[0016]

However, in the above-described internal combustion engine, when opening the exhaust valve 8 for engine braking or recirculation of exhaust gas during a period other than the normal exhaust stroke, a predetermined lift (lift) is required. ) To open the exhaust valve 8 or release the oil pressure in the oil passage 5 to control the opening of the exhaust valve 8 other than during the normal exhaust stroke. However, there was a problem as described in detail below.

That is, when controlling the opening of the exhaust valve 8 for engine braking, the larger the lift of the exhaust valve 8 is, the better the braking performance is. However, the larger the lift of the exhaust valve 8 is, the longer the opening time is. As a result, the seating time with respect to the valve seat is shortened, and the cooling efficiency of the exhaust valve 8 configured to cool by heat transfer to the water-cooled cylinder head is reduced. There was a problem that the cooling of the valve 8 was insufficient and durability was deteriorated.

For this reason, the lift must be set relatively small so that the exhaust valve 8 can be cooled well even in a region where the engine speed is high, and in a region where the engine speed is relatively low. Although there was room for improving the braking performance by increasing the lift, it was not possible to achieve it.

Further, when the opening of the exhaust valve 8 is controlled to recirculate the exhaust gas, the exhaust gas is taken into the combustion chamber during the intake stroke and the lean combustion is performed. Even if a good combustion state can be obtained without hindrance in the light load operation region, the combustion state becomes poor in the high load operation region where the ratio of air to fuel is small, and soot-rich black smoke is easily generated.

For this reason, effective NOx in the light load operation region
If the lift is set relatively large so that the amount of exhaust gas can be reduced, the upper limit of the load operation area where exhaust gas can be recirculated due to the regulation of particulates (particulate matter in engine exhaust) is set relatively low. Even in a relatively high load operation range, the lift of the exhaust valve 8 is reduced to suppress the recirculation amount of the exhaust gas, and there is a room for reducing the NOx. I couldn't.

The present invention has been made in view of the above-mentioned circumstances, and operates the lift of the exhaust valve when controlling the opening of the exhaust valve for engine braking or exhaust gas recirculation other than the normal exhaust stroke. An object of the present invention is to provide an internal combustion engine that can be appropriately changed according to a state.

[0022]

SUMMARY OF THE INVENTION The present invention is directed to a master piston operated by a rocker arm and connected to the master piston via an oil passage, and when pressure is generated in the oil passage by the operation of the master piston. , A lifter body sliding at least one of the master piston and the slave piston facing the oil passage, and an anti-oil passage of the lifter body. A push pin provided to be able to protrude and retract on the side, and a first elastic body disposed in the lifter body so as to be able to hold the push pin at a predetermined overhang position,
The present invention relates to an internal combustion engine, characterized by comprising a lock mechanism for appropriately fixing / releasing the push-in / out operation of the push pin at the extended position.

When such a configuration is applied to a master piston, the lifter body is pushed up by a rocker arm via a push pin, and when applied to a slave piston, an exhaust valve is connected to a push pin. Since it will be pushed down by the lifter body via
In either case, if the locking mechanism prevents the push pin from moving in and out, the operation stroke of the push pin is kept relatively large, and if the locking mechanism releases the push pin from moving in and out, the push pin is released. The operating stroke is reduced by the stroke of the pin retreating against the restoring force of the first elastic body, and by changing the operating stroke of the master piston or the slave piston in this way, the lift of the exhaust valve is reduced. Can be changed as appropriate.

Further, according to the present invention, the lock mechanism is provided so that the lock mechanism is loosely fitted to the push pin so as not to hinder the retracting operation and can be displaced only in a direction substantially perpendicular to the operation direction of the push pin. A lock plate accommodated in the lifter body, a second resilient body disposed in the lifter body so as to hold the lock plate at a position where the lock plate is loosely fitted to the push pin, and a loosely fitted position of the lock plate to the push pin. A lock hydraulic path for applying a hydraulic pressure so as to displace the second elastic body against the restoring force of the second elastic body, and an engagement recessed at an appropriate position of a push pin so as to engage the lock plate. It is possible to form with a groove.

With this arrangement, when the lock plate is displaced from the loosely-fitted position on the push pin against the restoring force of the second elastic body by applying a hydraulic pressure to the lock hydraulic path, the lock plate is disengaged. The plate is engaged with the engagement groove of the push pin, and the push-in / out operation of the push pin with respect to the lifter main body is fixed, and the hydraulic pressure of the lock hydraulic path is released to release the lock plate by the restoring force of the second elastic body. When the push pin is returned to the position where the push pin is loosely fitted, the fixing of the push-out operation of the push pin is released.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an example of an embodiment of the present invention, in which the same reference numerals as in FIG. 6 denote the same parts, and the basic configuration is shown in FIG. This embodiment is the same as the conventional one, but the feature of the present embodiment is that the master piston 2a for engine braking, the master piston 2b for exhaust gas recirculation, and the slave piston 6 are configured to be able to change the operation stroke. It is in.

That is, as shown in FIG. 1, the engine piston master piston 2a and the exhaust gas recirculation master piston 2b according to the present embodiment are provided on the lifter body 17 which slides toward the oil passage 5a or 5b. Pin hole 18 on passage side
And a spring 19 (first elastic body) is disposed at the deepest portion of the pin hole 18, and a push pin 20 is disposed in the pin hole 18 so as to be freely retractable. Can be held at a predetermined overhang position, and the lifter body 17 is pushed up by a rocker arm 19a or 19b (see FIG. 6) via a push pin 20.

Further, the push-in / out operation of the push pin 20 is configured so that it can be appropriately fixed / released (fixed state in FIG. 1) at a predetermined overhang position by a lock mechanism. A lock plate 22 accommodated in the slide chamber 21 in the lifter main body 17 so as to be loosely fitted to the pin 20 so as not to hinder the retracting operation and to be displaceable only in a direction substantially perpendicular to the operation direction of the push pin 20; A spring 23 (a second elastic body) disposed on one side of the slide chamber 21 so as to hold the lock plate 22 at a position where the lock plate 22 is loosely fitted to the push pin 20. A lock hydraulic path 24 for applying a hydraulic pressure so as to displace the pin 23 from the play-fitting position against the restoring force of the spring 23; Engaging groove is recessed in the appropriate position of the push pins 20 so as to engage the lock plate 22 2
5.

Here, the lock hydraulic passage 24 is formed near the insertion position of the master piston 2a for engine brake and the master piston 2b for exhaust gas recirculation, and slidably contacts the outer peripheral surfaces of the respective lifter bodies 17. An oil supply hole 26 that opens widely on the wall surface, and a slide chamber 21 in the lifter body 17 that communicates with the opening of the oil supply hole 26.
And a communication hole 27 opened on the other side.

The structure of the slave piston 6 in this embodiment is substantially the same as that of the master piston 2a for engine brake and the master piston 2 for exhaust gas recirculation described above.
As shown in FIG. 2, a pin hole 2 is formed in the lifter body 28 on the side opposite to the oil passage, which slides toward the oil passage 5 as shown in FIG.
9 is recessed, and a spring 30 is provided at the deepest portion of the pin hole 29.
(First elastic body), and a push pin 31 is disposed in the pin hole 29 so as to be able to come and go.
1 can be held in a predetermined overhang position,
The exhaust valve 8 (see FIG. 6) is pushed down by the lifter body 28 via the push pin 31.

That is, the push pin 31 of the slave piston 6 can be also used as having the same function as the conventional actuator pin 10 (see FIG. 6).

Further, the push-in / out operation of the push pin 31 is configured so as to be able to be appropriately fixed / released (fixed state in FIG. 2) at a predetermined overhang position by a lock mechanism. A lock plate 33 accommodated in the slide chamber 32 in the lifter main body 28 so as to be loosely fitted to the pin 31 so as not to hinder the retracting operation and to be displaceable only in a direction substantially perpendicular to the operation direction of the push pin 31; A spring 34 (second elastic body) disposed on one side of the slide chamber 32 so as to be able to hold the lock plate 33 at a position where the lock plate 33 is loosely fitted to the push pin 31.
The lock hydraulic path 35 for applying a hydraulic pressure so as to displace the spring 34 from the play-fitting position against the restoring force of the spring 34, and the push pin 31 is recessed at an appropriate position to be able to engage the lock plate 33. And the engagement groove 36.

Here, the lock hydraulic passage 35 has an oil supply hole 37 formed in the vicinity of the insertion position of the slave piston 6 so as to open widely on a wall surface which is in sliding contact with the outer peripheral surface of the lifter body 28. A communication hole 38 is formed on the other side of the slide chamber 32 in the lifter main body 28 so as to communicate with the opening of the oil supply hole 37.

In each of the master piston 2a for engine brake, the master piston 2b for exhaust gas recirculation, and the slave piston 6, as shown in FIG. 1 and FIG. To push the lock plates 22, 33 to the push pins 20, 31.
The lock plates 22, 33 are engaged with the engagement grooves 25, 36 of the push pins 20, 31 when the springs 19, 30 are displaced against the restoring forces of the springs 19, 30 from the loosely fitted position with respect to the lifter bodies 17, 28. Push pins 20, 31 for
3 and 4, the lock plates 22 and 33 are pushed by the restoring force of the springs 23 and 34 by releasing the hydraulic pressure of the lock hydraulic paths 24 and 35, as shown in FIGS. When the push pins 20 and 31 are returned to the positions where they are loosely fitted, the locking of the push pins 20 and 31 out of the way is released.

Therefore, if the lock mechanism is turned on to fix the push-in / out operation of the push pins 20 and 31, the operation stroke is kept relatively large, and if the lock mechanism is turned off, the push pin 20 and 31 are turned off. , 31
Is released, the push pin 20,
The operation stroke is reduced by the stroke (x, y in FIGS. 3 and 4) in which the spring 31 retreats against the restoring force of the springs 19, 30, and thus the master piston 2a, 2b or the slave piston 6 is reduced. The lift of the exhaust valve 8 can be changed as appropriate by changing the operation stroke of.

In particular, as shown in this embodiment, if both the master piston 2a for engine braking and the master piston 2b for exhaust gas recirculation and the slave piston 6 can change the working stroke, FIG. As shown, the master piston 2a, 2b side and the slave piston 6
A when the lock mechanisms on both sides of the master pistons 2a and 2b are turned on and the lock mechanism on the side of the slave piston 6 is turned off and B when the lock mechanisms on the master pistons 2a and 2b are turned off. When the lock mechanism on the slave piston 6 side is turned on, C when the lock mechanisms on both the master pistons 2a, 2b and the slave piston 6 are turned off D, the oil pressure in the oil passage 5 is released and the normal exhaust is performed. When the opening control of the exhaust valve 8 is not performed except during the stroke, a five-stage lift pattern such as E can be realized.

Therefore, according to the above embodiment, when controlling the opening of the exhaust valve 8 for the purpose of engine braking or exhaust gas recirculation other than the normal exhaust stroke, the lift of the exhaust valve 8 is appropriately adjusted according to the operating state. When the engine brake is operated, the lift is reduced to ensure good cooling of the exhaust valve 8 in a region where the engine speed is high, and the durability of the exhaust valve 8 is ensured. The brake performance can be improved by maintaining the performance and increasing the lift of the exhaust valve 8 in a region where the engine speed is relatively low.

At the time of exhaust gas recirculation, the lift is increased in the light load operation range to effectively reduce NOx, and the exhaust valve 8 is operated in the relatively high load operation range.
By reducing the lift, the amount of exhaust gas recirculation can be suppressed to reduce the amount of NOx while preventing the generation of soot-rich black smoke.

It should be noted that the internal combustion engine of the present invention is not limited to the above-described embodiment, but may be any other than the internal combustion engine having both the function of the compression pressure release type engine brake and the function of the exhaust gas recirculation. It can be applied to an internal combustion engine equipped with a master piston and a slave piston so that only one function can be exhibited.When opening the exhaust valve for engine braking, the effectiveness of the brake is simply reduced to the slope of downhill etc. It is needless to say that the lift may be changed for the purpose of adjusting accordingly, and that various changes may be made without departing from the scope of the present invention.

[0041]

According to the internal combustion engine of the present invention described above, when the opening of the exhaust valve is controlled for the purpose of engine braking or exhaust gas recirculation other than the normal exhaust stroke, the lift of the exhaust valve is changed according to the operating state. For example, when controlling the opening of the exhaust valve for engine braking, the lift is reduced so that the exhaust valve can be cooled well in a region where the engine speed is high. While maintaining the same braking performance as before while maintaining the durability of the engine, it is possible to improve the braking performance by increasing the lift of the exhaust valve in a region where the engine speed is relatively low, and to improve the exhaust gas recycle. When controlling the opening of the exhaust valve for circulation, the lift is increased in the light load operation range to achieve effective reduction of NOx, and exhaust is performed in the relatively high load operation range. By reducing the lift of the gas valve, the recirculation amount of the exhaust gas can be suppressed, and an excellent effect that NOx can be reduced while preventing generation of soot-rich black smoke can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a master piston according to an example of an embodiment of the present invention.

FIG. 2 is a sectional view of a slave piston according to an example of an embodiment of the present invention.

FIG. 3 is an operation explanatory view of the master piston of FIG. 1;

FIG. 4 is a diagram illustrating the operation of the slave piston of FIG. 2;

FIG. 5 is a diagram showing a lift pattern in an example of an embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional example.

FIG. 7 is a diagram showing the arrangement of devices for a plurality of cylinders in a conventional example.

[Description of Signs] 2a Master piston for engine brake 2b Master piston for exhaust gas recirculation 5 Oil passage 5a Oil passage 5b Oil passage 6 Slave piston 8 Exhaust valve 17 Lifter body 19 Spring (first elastic body) 19a Rocker arm 19b Rocker arm 20 Push pin 22 Lock plate 23 Spring (second elastic body) 24 Hydraulic path for locking 25 Engagement groove 28 Lifter body 30 Spring (First elastic body) 31 Push pin 33 Lock plate 34 Spring (Second spring) Resilient body) 35 Lock hydraulic path 36 Engagement groove

Claims (2)

[Claims] 1. A master piston operated by a rocker arm, and a slave connected to the master piston via an oil passage and opening an exhaust valve when a pressure is generated in the oil passage by the operation of the master piston. In an internal combustion engine having a piston, at least one of a master piston and a slave piston is provided so as to be able to protrude and retract from a lifter main body which slides toward an oil passage on a side opposite to the oil passage of the lifter main body. A push pin, a first elastic body disposed in the lifter body so as to hold the push pin at a predetermined overhang position, and a lock for appropriately fixing / releasing the push-in / out operation of the push pin at the overhang position An internal combustion engine characterized by comprising a mechanism. 2. A lock plate, which is loosely fitted to the push pin so as not to hinder the retracting operation and is accommodated in the lifter body so as to be displaceable only in a direction substantially perpendicular to the operation direction of the push pin, and the lock plate. A second elastic body disposed in the lifter body so as to hold the plate at a position where the second elastic body is loosely fitted to the push pin; and a restoring force of the second elastic body from the loosely fitted position of the lock plate to the push pin. The lock mechanism is constituted by a lock hydraulic path for applying a hydraulic pressure so as to displace the lock plate, and an engagement groove recessed at an appropriate position of the push pin so as to be able to engage the lock plate. The internal combustion engine according to claim 1, wherein: