JP3443514B2 - Actuator for operating exhaust valve of engine brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to the gas pressure of an internal combustion engine.
Control the braking force generated in the vehicle by adjusting
Engine braking systems, especially for internal combustion engines
The opening of the exhaust valve during the compression and expansion strokes is determined by the engine speed.
Exhaust valve operation of the engine brake device operated according to etc.
Related to actuators. [0002] 2. Description of the Related Art This type of exhaust valve operating actuator is
As an invention, Japanese Patent Application No. 8-182 filed by the present applicant earlier.
No. 577 (filed on Jul. 12, 1996) and drawings
There is what was described in. [0003] The outline will be described with reference to FIGS.
The actuator according to the earlier application of
The front part which operates the opening degree of the exhaust valve according to the advance position
The piston 2 and the front piston 2
The rear piston 3 is slidably housed, and
A stopper for restricting the rearward displacement of the rear piston 3 is provided in the cylinder 1.
The paring 4 is attached and the bottom wall of the cylinder 1
And the rear piston 3, the front piston 2 and the rear piston 3
A first working chamber 5 and a second working chamber 6 are respectively formed between each.
You. The bottom of the cylinder 1 facing the first working chamber 5
A first supply / discharge port 8 connected to the fluid supply / discharge means 7 is provided on the wall.
Are formed in the first working chamber 5 on the side wall of the cylinder 1.
A portion near the bottom wall facing, and a substantially central portion in the axial direction facing the second working chamber 6
Has a connection port 9 and a second supply / discharge port 10 respectively.
The connection port 9 and the second supply / discharge port 10 switch the flow path.
They are connected to one another via a valve 11. This flow path switching valve
In the normal state, the second supply / discharge port 10 is connected to the discharge passage 1.
When the signal hydraulic pressure is received, the second supply / discharge port
The communication between the port 10 and the discharge passage 12 is interrupted and the second supply / discharge port is opened.
The port 10 communicates with the connection port 9. When the accelerator pedal is depressed,
During normal operation, the fluid supply / discharge means 7 causes the first working chamber 5 to be on the discharge side.
To the rear piston 3 and the front as shown in FIG.
The piston 2 is maintained in the initial position where it has been retracted.
The accelerator pedal is turned off from this normal state,
When the engine brake operation is performed by the operator, the fluid supply
By the combination operation of the discharging means 7 and the flow path switching valve 11,
The advance position of the piston 2 is stepped according to the engine speed etc.
Adjustment operation. That is, when the engine speed is low, FIG.
As shown in the figure, the fluid supply / discharge means 7 operates in the first working chamber 5.
While supplying the fluid, the flow path switching valve 11
To the discharge passage 12 side, and the rear piston 3
It is stripped by the force of the working fluid introduced into the moving chamber 5.
The piston 2 to the first position.
Push up to the position. As a result, the front piston 2 is initially
Stroke S from position₁The exhaust valve opening.
Operate to the first stage opening (small opening). When the engine rotation speed is high, FIG.
As shown in the figure, the fluid supply / discharge means 7 operates in the first working chamber 5.
While supplying the fluid, the flow path switching valve 11
Is communicated with the first working chamber 5 side and the working flow is also supplied to the second working chamber 6.
Supply the body. This causes the front piston 2 to perform the second operation.
Receives the pressure of the working fluid in the chamber 6 and separates from the rear piston 3
To advance to the second stage position. This allows the front fixie
2 is S₁Stroke S larger than_TwoJust displace
The opening of the exhaust valve is adjusted to the second stage opening (large opening). [0008] However, as described above,
When the exhaust valve is set to a large opening,
The operation of the flow path switching valve 11 causes the first working chamber 5 and the second
When the moving chamber 6 is communicated, the front and back of the rear piston 3
And the same pressure acts on the rear piston 3 on the advance side and the retreat side.
The thrust is balanced and the rear piston 3 is within the stroke range.
It is possible to stop at any position. And this
When the rear piston 3 moves as shown by the broken line in FIG.
When stopped at the retraction control position, the peripheral wall of the rear piston 3 is connected
The port 9 is closed to allow the first working chamber 5 to move to the second working chamber 6.
The supply of the working fluid is cut off and the front piston 2 is moved to the second stage.
This causes a problem that the operation cannot be performed smoothly. Accordingly, the present invention provides a method for switching the opening degree of an exhaust valve.
So that it can be performed smoothly and always get reliable operation
Actuator for operating exhaust valve of engine brake device
Data. [0010] The present invention solves the above-mentioned problems.
As a solution to this, it is possible to move it back and forth inside the cylinder.
The opening of the exhaust valve of the internal combustion engine according to its advanced position
To operate the front piston and this front piston in the cylinder
Retractable to the back side of the ton and against the front piston
A rear piston that is housed detachably and this rear piston
Position that regulates the advance position of the tool to a predetermined position in the cylinder
Between the bottom wall of the cylinder and the rear piston.
A first working chamber formed in the front piston and the rear piston.
A second working chamber formed between the stons and the first working chamber
Fluid supply / discharge means for supplying / discharging the working fluid to / from the cylinder,
A connection port formed on a side wall on the bottom side of the first working chamber;
2 The working chamber is selectively connected to the connection port or the discharge passage.
A flow path switching valve through which the fluid supply / discharge means and the flow path
Combined operation of switching valves to the first and second working chambers
Control the supply and discharge of working fluid to the front piston
Exhaust of engine brake device that switches the advance position to multiple stages
In the valve operating actuator,The rear piston is
Adjust the cylinder so that it is located below the front piston
While being arranged along the vertical direction,The rear piston
When the piston is in the retraction restriction position,
Providing a conduction path for conducting the discharging means and the connection port,The first
Before the working fluid is supplied from the working chamber to the second working chamber.
The rear piston moves backward to the restricted position due to its weight.
Made to retreat. When moving the front piston to the maximum
When the working fluid is supplied to the first working chamber and the second working chamber,
The same pressure acts on the front and back of the rear piston, and the working fluid
The thrust on the advance side of the rear piston and the thrust on the reverse side due to
Meet each other.At this time, the rear piston is
The fluid suction / discharge means and the connection port
They will communicate through the passage. Therefore, the front
When making the maximum advance displacement of the stone,
Supply of working fluid to the second working chamber is performed by the rear piston
The rear piston always operates constantly without interruption
And there is little variation in the operation of the actuator.
Disappears. [0011] [0012] [0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.
A description will be given below. 1 to 3 show a first embodiment of the present invention.
In the figure, reference numeral 21 is formed in the cylinder head S of the engine.
An exhaust valve 22 for opening and closing the exhaust port E,
A driving means 23 for driving the opening and closing of the
The lift amount (opening degree) of the exhaust valve 21
Variable lift amount during the compression and expansion strokes of the fuel engine
4 is an actuator according to the present invention. The exhaust valve 21 has a stem 21a formed of a syringe.
Slides on an unillustrated tubular stem guide fixed to the dahead S
You will be guided. The driving means 22 is mounted on the cylinder head S.
Rocker shaft 24 extending along the longitudinal direction
And a rocker swingably supported by the rocker shaft 24.
The rocker arm 25 and the rocking center of the rocker arm 25
A swinging center variable mechanism 26 for displacing substantially vertically,
By operating the swing center variable mechanism 26, the exhaust valve 21 is reset.
The actuator 23 for variably operating the lift amount.
This is the schematic configuration. The rocker arm 25 swings substantially at its center.
Through a cam ring 27 described later of the center variable mechanism 26,
While being supported by the hook shaft 24, one extension end is
Valve actuation via push rod 28 and valve lifter 29
And the other extension end is above the stem 21a.
Directly engaged with the end. Valve cam 30 is a crankshaft
It rotates synchronously with the shaft (not shown).
Swing the arm 25 in synchronization with the rotation of the crankshaft.
It has become. The swing center variable mechanism 26 includes a rocker shaft
24 while being eccentrically supported while being rotatably supported by
The cam for rotatably fitting and supporting the rocker arm 25
The ring 27 and the cam ring 27 are extended integrally with the side of the cam ring 27.
The bending lever 31 is provided. Cam ring 27
The center of the circle formed by the outer peripheral surface is the rocking center of the rocker arm 25.
The rocking center of the rocker shaft 24 is
On the other hand, it is eccentric in a substantially horizontal direction by a predetermined amount. Because of this cam
Ring 27 is slightly centered on the axis of rocker shaft 24.
When rotated, the rocker arm 25 swings with the rotation.
The center is displaced substantially vertically. The rotation of this cam ring 27
The movement is performed by operating the bending lever 31, and the bending lever
The bar 31 is operated by the actuator 23
It has become. Here, the rocking center position of the rocker arm 25
Means that the valve lifter 29 is the base circle of the valve operating cam 30
(Hereinafter referred to as base circle contact state)
U. ) Specifies the lift amount (opening) of the exhaust valve 21.
At the initial position where the actuator 23 does not operate.
Of the exhaust valve 21 in the base circle contact state.
And the actuator 23 operates to swing
When the center is displaced, the
The lift amount of the air valve 21 changes according to the displacement of the swing center.
It is supposed to be. On the other hand, the actuator 23 is shown in FIGS.
Bolts on the upper end of the cylinder head S as shown in
A cylinder 33 is provided on the upper part of the
Front piston 34 and rear piston 3 in cylinder 33
5 are housed slidably and detachably from each other.
You. The cylinder 33 is vertically attached to the body 32.
The lid member 36 is fitted and fixed to the upper end of the circular hole recessed along
It is configured. Further, both pistons 34, 3
5 are arranged in series in the cylinder 33,
Between the bottom wall 33a and the rear piston 35, the front piston 3
4 and the rear piston 35 between the first working chamber 37 and the second working chamber, respectively.
The working chamber 38 is separated. Note that the front piston 34 and
Empty space formed between the upper wall (cover member 36) of the Linda 33
The space communicates with the discharge passage through the drain port 39
I have. Then, the rear piston 35 is
In the center of the upper surface of the piston body, against the back of the front piston 34
A small-diameter cylindrical portion 35a that can be separated and connected is integrally protruded.
You. On the other hand, the front piston 34
A piston slidably penetrating the lid member 36 at the center of the surface
A rod 40 is protruded, and its piston rod 40
Of the bending lever 31 of the swing center variable mechanism 26
The tip is engaged. Therefore, the bending lever 31
Is rotated in accordance with the advance position of the front piston 34.
You. Also, at the substantially central portion in the axial direction of the inner peripheral surface of the cylinder 33,
The stopper ring 41 is fitted and fixed, and the rear
When the motor 35 advances a set amount in the cylinder 33,
Outside the upper surface side of the rear piston 35 with respect to the stopper ring 41
The peripheral part comes into contact. This stopper ring
The plug 41 constitutes the advance position restricting means in the present invention. The first working chamber 37 is a cylinder.
33 via a first supply / discharge port 44 formed on the bottom wall 33a
The working fluid is supplied and discharged, and the second working chamber 38 is
Formed slightly above stopper ring 41 on side wall 33
Supply and discharge of the hydraulic fluid through the second supply / discharge port 45
It is supposed to be. The first supply / discharge port 44 is connected to a serial port of the body 32.
To the first flow path switching valve 46 disposed below the
The first passage switching valve 46 is connected to supply passage according to the operation of the first passage switching valve 46.
To selectively communicate with either the passage 47 or the discharge passage 48
Swelling. The first flow path switching valve 46 has one end of a valve hole 49.
When the other end communicates with the supply passage 47 and the discharge passage 48, respectively.
In both cases, the first supply and discharge
The port 44 is formed with an opening. And inside the valve hole 49
Has a spoon that moves forward and backward under the pressure of the supply passage 47.
The spool 50 is slidably housed and the spool 5
The spring 51 that urges 0 toward the supply passage 47 is housed.
Have been. The annular groove 52 is formed on the outer periphery of the spool 50.
And communicates with the peripheral wall the annular groove 52 and the inside.
A communication hole 53 is formed along the radial direction, and further, a supply passage
The end face on the side facing 47 communicates with the supply passage 47 and the inside.
The passage hole 54 is formed along the axial direction. And
Inside the spool 50, a passage hole 54 along the axial direction is provided.
Allows only flow in the direction of the communication hole 53 along the radial direction from
A check valve 55 is incorporated. The spool 50 advances into the valve hole 49.
A stopper 56 that regulates displacement in the outgoing direction is attached
As shown in FIGS. 2 and 3, the spool 50
When it comes into contact with the stopper 56
So that the annular groove 52 communicates with the first supply / discharge port 44
Has become. Note that the spool 50 is
The first supply / discharge port 44 is discharged at the initial position where the
It opens to the passage 48 side so that both can communicate with each other.
ing. Therefore, the first flow path switching valve 46 is
When high-pressure hydraulic fluid is introduced into the supply passage 47,
Therefore, the spool 50 advances to the maximum position, where it is supplied.
The check valve 55, the communication hole 53, and the annular
The first operation is sequentially performed through the groove 52 and the first supply / discharge port 44.
It is introduced into the moving chamber 37. And also in the supply passage 47
When the pressure drops, the pressure drops
The tool 50 retracts and supplies the first working fluid in the first working chamber 37 with the first fluid.
Outflow to the discharge passage 48 through the discharge port 44 and the valve hole 49
Let it. On the other hand, the second supply / discharge port 45 is
Flow path switching valve disposed on the side of the cylinder 33 portion
57 in accordance with the operation of the second flow path switching valve 57.
Selectively communicates with either the first working chamber 37 or the discharge passage 48.
Through. The second flow path switching valve 57 has a valve hole 63 in which
The valve hole 63 is formed in parallel with the
When the end (lower end in the figure) communicates with the signal pressure introducing passage 58
In both cases, the vicinity of the other end (the upper end in the figure) is connected to the discharge passage 48.
Through. The second supply / drainage is provided on the side wall of the valve hole 63.
The port 45 is opened and the first working chamber 37
An opening is formed in the connection port 59 communicating with the vicinity of the bottom wall 33a.
Have been. The signal pressure introducing passage is provided in the valve hole 63.
The spool 60 which moves forward and backward under the pressure of 58
And the spool 60 is introduced with signal pressure.
A spring 61 biasing in the direction of the passage 58 is housed.
You. The spool 60 is located outside the substantially central portion in the axial direction.
An annular groove 62 having a set width is formed around the circumference.
The width of 62 is between the second supply / discharge port 45 and the connection port 59.
It is set almost equal to the distance. In addition, in the valve hole 63
At the other end (upper end), a strike also serves as a spring retainer.
Hopper 64 is attached, and as shown in FIG.
When the tool 60 is maximally displaced and comes into contact with the stopper 64
In addition, the second supply / discharge port 45 and the connection port 59
0 to communicate with each other through an annular groove 62
You. Furthermore, the spool 60 is connected to the signal pressure introduction passage 58.
The second supply / drain port at the initial position where it is retracted to the maximum in the direction
45 is opened to the drain port 65 side, thereby connecting
When the communication between the port 59 and the second supply / discharge port 45 is cut off,
Then, the second supply / discharge port is communicated with the discharge passage 48 side. In the drawing, reference numeral 66 denotes a supply passage for supplying the hydraulic fluid to the supply passage 47.
An oil pump for sending pressure to the signal pressure introduction passage 58
The supply passage 47 and the signal pressure introduction passage 58
The oil pump is installed in the middle of each
66 side or drain port 67a, 68a side selectively
The three-way first and second solenoid valves 69 to communicate with each other are the driver
Brake signal and crank due to engine brake operation
The solenoid valve 67, based on the engine rotation signal from the angle sensor, etc.
68 is a controller for switching control. Of this embodiment
In this case, the fluid supply / discharge unit according to the present invention includes a first supply / discharge port
44, a first flow path switching valve 46, an oil pump 66, a first
It is constituted by a magnetic valve 67 and the like. Here, the rear piston 35 is provided at the bottom thereof.
A concave portion 70 having a set diameter is formed on the surface, and
An annular groove 71 is formed at a constant height position.
0 and the annular groove 71 are formed by a plurality of through holes 72 along the radial direction.
Are communicating with each other. The recess 70 is provided at the rear
Is in the retreat restriction position (contacts the bottom wall of the cylinder 33).
Position), the diameter communicating with the first supply / discharge port 44
The annular groove 71 is formed with a rear
When the ton 35 is in the retreat restriction position, the connection port 59
Is formed at a height position that communicates with. That is, the rear
When the stone 35 is in the retreat restriction position, the first supply / discharge port
Port 44 and connection port 59 are provided with a recess 70, a through hole 72,
In addition, conduction is provided through the annular groove 71.
The concave portion 70, the through hole 72, and the annular groove 71
It forms a conduction path in the light. The operation of this embodiment will be described below. First, when the accelerator pedal is depressed,
During the operation of
The first and second solenoid valves 67 and 68 are each provided with a drain port 67.
a, 68a. Therefore, as shown in FIG.
The hydraulic fluid pumped from the oil pump 66 to the drain
Outlets 67a, 68a and communicate with the supply passage 47.
No hydraulic fluid is supplied to each downstream side of the pressure introduction passage 58,
The first working chamber 37 and the second working chamber 38 are both supplied with working fluid.
It is in a state not to be able to. Therefore, the front piston 3
4 is the initial position where it has retracted to the maximum, and the swing center is possible.
The changing mechanism 26 is at the maximum ascending position at the rocking center of the rocker arm 25.
The exhaust valve 21 in the base circle contact state.
The shift amount is set to 0. At this time the engine brake
No braking force is generated by the device. Next, in the low to middle engine speed range,
The cell pedal is released and the driver
When the on-brake operation is performed, the controller 69
The switching signal is output only to the first solenoid valve 67. this
Thus, the oil pump 66 is located downstream of the supply passage 47.
High-pressure hydraulic fluid is supplied from the
As a result, as shown in FIG.
50 advances until it comes into contact with the stopper 56, and
The check valve 55, the communication hole 53, and the annular groove 5
2, and the first working chamber via the first supply / discharge port 44 in order.
37. As a result, the rear piston 35
Advances and displaces in a state of being integrated with the front piston 34,
When it hits the stopper ring 41, the displacement
Stop. Therefore, the front piston 34 is
It is held at the intermediate advance position in a state where it overlaps with the ton 35.
The rocking center variable mechanism 26
Slightly lower the swing center to abut the base circle
Change the lift amount of the exhaust valve 21 to the set small lift amount X
You. As a result, the generated engine braking force
It becomes suitable for the engine speed in the shift range. At this time, the supply flow from the first working chamber 37 is
The backflow of the hydraulic fluid to the side of the passage 47 is prevented by the flow of the first passage switching valve 46.
Blocked by check valve 55 installed in pool 50
As a result, the pressure in the first working chamber 37 does not move the spool 50.
As long as it is maintained by this check valve 55. On the other hand, in the high engine speed range,
When the engine brake operation is performed by the
Switch from the motor 69 to the second solenoid valve 68
A signal is output. Then, downstream of the signal pressure introduction passage 58
Side is supplied with high-pressure hydraulic fluid, and as a result,
As shown in FIG. 3, the spool 60 of the second flow path switching valve 57
Until it comes into contact with the stopper 64.
You. When the spool 60 advances in this way,
The second supply / drain port 45 that was in communication with the drain port 65 at
To the connection port 59 via the annular groove 62 of the spool 60
Communication, whereby the first working chamber 37 and the second working chamber 38
Communicate with each other. Thereby, the high pressure of the supply passage 47 is
Hydraulic fluid enters the second working chamber 38 via the first working chamber 37
Introduced and the front piston 34 is actuated by the action of the hydraulic fluid.
Further advanced, and the maximum advance against the lid member 36 is reached.
Stop the displacement at the exit position. As a result, the swing center variable mechanism 26 is
Lower the swing center of the arm 25 further, and
The lift amount of the exhaust valve 21 in the state where the vehicle is in contact with the small lift amount X
The lift amount is changed to the set lift amount Y which is larger than that. to this
Therefore, the generated engine braking force is
It becomes suitable for the rotation speed. Here, the first working chamber 37 to the second working chamber 3
8 when the hydraulic fluid is introduced into the rear piston 35
Since the same pressure acts on the front and back,
The thrust in the advance direction and the thrust in the reverse direction of the partial piston 35 are
At this time, the cylinder 33
Is formed along the vertical direction.
The ton 35 is restricted by its own weight as shown in FIG.
Retreat to position. And like this, the rear piston 3
5 moves back to the retreat restriction position, the rear piston 35
The annular groove 71 faces the connection port 59, and the
1 The supply / discharge port 44 passes through the recess 70 of the rear piston 35
The connection port 59 communicates with the connection port 59 through the hole 72 and the annular groove 71.
Pass. Therefore, at this time, the first working chamber 37 and the
2 The communication of the working chamber 38 is cut off by the rear piston 35.
And the first supply via the first working chamber 37
Supply of the hydraulic fluid from the discharge port 44 to the second working chamber 38 is confirmed.
You can continue. As a result, the front piston 34
It is quickly displaced to the advanced position and the controller 69
Until the next signal is input to the
Really retained. In the case of this actuator, the first operation
When the working fluid is introduced into the second working chamber 38 from the working chamber 37
The rear piston 35 stops at an unspecified position
Instead of stopping at the reverse control position due to its own weight.
The hydraulic fluid from the first supply / discharge port 44 to the second working chamber 38
Is always supplied to the concave portion 70, the through hole 72, and the annular groove 7.
It is done through 1. Therefore, the front piston 35
There is no variation in the advance operation, and a stable operation is always obtained.
It becomes possible. Further, when the engine rotation speed is in a high rotation range.
Again, the second solenoid valve 68 only
Is output to the drain port 68a.
Is opened, and the pressure on the downstream side of the signal pressure introduction passage 58 decreases.
You. Thereby, the spool 60 of the second flow path switching valve 57
Is retracted by the spring force of the spring 61 as shown in FIG.
To make the second supply / discharge port 45 communicate with the drain port 65.
Become so. Therefore, the hydraulic fluid in the second working chamber 38
Is discharged through the second supply / discharge port 45 and the drain port 65
Spills into passage 48, causing rear piston 35 to advance
The front piston 34 moves to the rear
Retreat until it hits the cylindrical portion 35a of the piston 35
It is held at the intermediate regulation position. This makes the swing center variable
The mechanism 26 raises the rocking center of the rocker arm 25 and ejects it.
The lift amount of the air valve 21 is changed again to the small lift amount X,
Engine suitable for low and middle engine speeds
Braking force can be obtained. Further, from this state, the engine brake
When the release operation is performed, the switching signal is also output to the first solenoid valve 67.
Output, the drain port 67a is opened, and
The pressure on the downstream side of the passage 47 decreases. Thereby, the first
The spool 50 of the flow path switching valve 46 has a spool 50 as shown in FIG.
Retracts with the spring force of the spring 51, and
The opening 44 communicates with the discharge passage 48 side. At this time, the first
The working fluid in the working chamber 37 is discharged through the first supply / discharge port 44.
Outflow passage 48, rear piston 35 is front piston
34 and is displaced backward until it reaches the retreat restriction position. This
As a result, the front piston 34 is returned to the initial position,
The center variable mechanism 26 sets the rocking center of the rocker arm 25 to the initial position.
And the lift amount of the exhaust valve 21 is set to zero. I
Therefore, the braking force generated by the engine braking device is generated.
Disappears. Next, a second embodiment of the present invention will be described with reference to FIGS.
6 will be described. In the following, FIGS.
The same reference numerals in the drawing denote the same parts as in the first embodiment shown in FIG.
And the description of the same parts as in the first embodiment is omitted.
And The engine brake device of this embodiment is
The structure of the air valve 21 and the swing center variable mechanism 26 is the first embodiment.
Has the same configuration as that of
The configuration of the operating actuator 73, in particular, its
The configuration of the one channel switching valve 74 according to the first embodiment
Is very different. That is, the actuator in this embodiment
In the case of 73, the supply port is provided on the bottom wall 33a of the first working chamber 37.
75 and a drain port 76 are provided in parallel,
75 communicates with the supply passage 47 via the check valve 77
Then, the drain port 76 side exhausts through the pressure control valve 78.
The first passage switching valve 74 communicates with the outlet passage 48.
It is constituted by a check valve 77 and a pressure control valve 78.
I have. Then, the check valve 77 is
1 The structure allows the flow of the working fluid in the working chamber 37 direction.
The pressure control valve 78 responds to the pressure in the supply passage 47.
Free piston 79 opens and closes drain port 76
Structure. More specifically, the pressure control valve 78
The valve hole 80 has one end (upper end) in the drain port 76,
The other ends (lower ends) communicate with the supply passages 47, respectively.
A discharge passage 48 is connected and connected in the vicinity of one end of the peripheral wall.
Free piston housed in valve hole 80
79 is a tape whose head can block the drain port 76.
And a supply passage 47 at the bottom thereof.
Pressure is applied. The pressure control valve 78 is connected to the supply passage 47
When the hydraulic fluid at a pressure is supplied, the free piston 79
Under the pressure, it moves upward and displaces, and the drain port 76
And shut off the first solenoid valve 67 from that state.
When the pressure in the supply passage 47 drops due to replacement,
The piston 79 is driven by the pressure of the working fluid in the first working chamber 37 and its own weight.
And the drain port 76 is connected to the discharge passage 48.
Let through. Further, the free piston 79 is provided with a drain port.
The pressure receiving surface on the upper side with the block 76 closed is the drain port.
Since only the top of the taper faces the gate 76,
After closing the port 76, the difference between the upper and lower pressure receiving areas
The drain port 76 can be tightly closed.
Therefore, this pressure control valve 78 is extremely simple.
Despite the simple structure, the pressure in the first working chamber 37 is reliably ensured.
Can be held. The actuator 73 in this embodiment
The other parts are the same as those of the first embodiment.
And a concave portion 70 and an annular shape on the bottom surface and the outer peripheral surface of the cylinder 33.
Grooves 71 are respectively formed, and the recess 70 and the annular groove 71 are formed as through holes.
It communicates by 72. These recesses 70, through holes
72 and the annular groove 71 constitute a conduction path in the present invention,
When the rear piston 35 is displaced to the retreat restriction position, the first
The supply / discharge port 44 and the connection port 59 are conducted. The actuator 73 switches the first flow path.
Although the structure of the valve 74 is different from that of the first embodiment,
First and second working chambers for operating the lift amount of the air valve 21
The supply and discharge of the hydraulic fluid to and from 37 and 38 are performed in exactly the same manner. This
About the lift amount operation of the exhaust valve 21 in the embodiment of FIG.
Although detailed description is omitted, the first embodiment is also used in this embodiment.
Like the embodiment, the first working chamber 37 and the second working chamber 38
When the hydraulic fluid is introduced, the first supply / discharge port is
The connection port 59 communicates with the connection port 59 through the through hole 72 and the annular groove 71.
Rear piston 35 which is retracted
Can reliably prevent the problem of shutting off the connection port 59.
Can be. The embodiment of the present invention has been described above.
Not limited to, for example, during the intake stroke of the internal combustion engine
Dedicated for engine brake control separately from the normal exhaust valve that opens
An exhaust valve is provided, and the exhaust valve is actuated according to the present invention.
It may be operated by data. [0053] As described above, the present invention provides:The rear piston is
Vertically position the cylinder below the front piston
Along with the rear piston.
When the piston is in the retreat restriction position,
And a connecting path for connecting the connecting port to the first working chamber.
When the working fluid is supplied to the second working chamber, the rear piston
Is retracted by its weight to the restricted position.
BecauseFirst action when the front piston is fully extended
Rear pipe whose supply of working fluid from the chamber to the second working chamber has receded.
It is no longer blocked by the surrounding wall of Ston,
As a result, the front piston always operates smoothly to the maximum extension position.
It is possible to secure it reliably.

[Brief description of the drawings] FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the embodiment. FIG. 3 is a longitudinal sectional view showing the embodiment. FIG. 4 is a longitudinal sectional view showing a second embodiment of the present invention. FIG. 5 is a longitudinal sectional view showing the embodiment. FIG. 6 is a longitudinal sectional view showing the same embodiment. FIG. 7 is a longitudinal sectional view showing a conventional technique. FIG. 8 is a longitudinal sectional view showing the same technology. FIG. 9 is a longitudinal sectional view showing the same technology. [Explanation of symbols] 21 ... exhaust valve, 23, 73 ... actuator, 33 ... cylinder, 34 ... front piston, 35 ... rear piston, 37 ... First working chamber, 38: second working chamber, 41 ... stopper ring (advance position restricting means), 44 ... first supply / discharge port (fluid supply / discharge means) 46 ... first flow path switching valve (fluid supply / discharge means) 48 ... discharge passage, 57: second flow path switching valve (flow path switching valve), 59 ... connection port, 66 ... oil pump (fluid supply / drainage means) 69 ... controller (fluid supply / discharge means) 70 ... recess (conduction path), 71 ... annular groove (conduction path), 72 ... through-hole (conduction path).

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-48-64504 (JP, A) JP-A-8-338215 (JP, A) JP-A 4-54907 (JP, U) JP-A 61-338 175511 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 13/06 F02D 13/02 F02D 13/04

Claims (1)

(1) A front piston which is housed in a cylinder so as to be able to advance and retreat, and controls an opening of an exhaust valve of an internal combustion engine in accordance with an advanced position thereof, and a front piston in the cylinder. A rear piston housed so as to be able to advance and retreat to the back side of the part piston, and to be detachable from the front piston; an advance position regulating means for regulating the advance position of the rear piston to a predetermined position in the cylinder; A first working chamber formed between a bottom wall of the first piston and the rear piston, a second working chamber formed between the front piston and the rear piston, and a working fluid supplied to and discharged from the first working chamber. A fluid supply / discharge means, a connection port formed on a side wall of the cylinder on the bottom side of the first working chamber, and a flow path switching valve for selectively communicating a second working chamber with the connection port or the discharge passage; The fluid supply / discharge means and the flow path switching valve Wherein the observed combined operation first, and controls the supply and discharge of hydraulic fluid to the second working chamber, the exhaust valve operating actuator of the engine braking device for switching the advanced position of the front piston in multiple stages, the rear piston is pre It is located below the piston
Thereby disposed along the sea urchin the cylinder in the vertical direction, the rear piston, when the piston is in the retracted restricting position, the guide passage to conduct a connection port fluid supply and discharge means is provided, the first working chamber The working fluid is supplied from the
When the rear piston moves back
An actuator for operating an exhaust valve of an engine brake device, characterized in that the actuator is retracted to the position of the engine.