JPH1030415A - Engine brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve mountability onto an engine by providing in a variable means a stopper member for regulating the maximum advancing position of a piston and a stopper mechanism going in and out of a cylinder to regulate the intermediate advancing position of the piston. SOLUTION: A variable means 23 provided in the upper part of an opening of a cylinder 31 is formed of a stopper member 46 for regulating the maximam advancing position of a piston 32 and a stopper mechanism 47 moving radially in and out of the cylinder 31 to regulate the intermediate moving position of the piston 12. The stopper member 46 consists of a flange part and tubular part 46a and the inner circumference of the upper surface of the piston 32 abuts against the lower end edge of the tubular part 46a to regulate the upward move more than a predetermined one. The stopper mechanism 47 is constituted from a sliding hole 49, a plunger 50 and oil pressure path 52, so that the whole device is simplified and compacted to improve the mountability on to an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine brake device mounted on a large vehicle such as a truck or a bus and utilizing an engine braking capability (compressor).

[0002]

2. Description of the Related Art As is well known, a large vehicle is provided with an engine brake device utilizing a braking ability of an engine such as a compression brake in addition to a service brake and a parking brake.
As this conventional engine brake device, for example, a variable valve lift compression brake described in Japanese Utility Model Laid-Open No. 4-54907 is known.

[0003] Referring to FIG. 8, this engine brake device comprises a power tard valve 1 supported by a cylinder head S of an engine to open and close a combustion chamber.
An opening / closing drive mechanism 2 arranged on the cylinder head S for opening and closing the power tard valve 1, a lift amount variable mechanism provided on the open / close drive mechanism 2 for varying the valve lift amount of the power tard valve 1, It has.

The power tard valve 1 includes a block 3
Is normally urged in the closing direction by the valve spring 4.

The opening / closing drive mechanism 2 includes a tapered block 6 slidably in contact with a tappet 5 engaged with an upper end of the power tard valve 1 and an air cylinder 7 for driving the tapered block 6 in the longitudinal direction within the elongated hole 3a. The taper block 6 and the air cylinder 7 also constitute the lift variable mechanism.

The tapered block 6 has a long plate shape,
The opening degree adjusting surfaces 6a to 6c are formed on the lower surface and extend in the front-rear direction. On the other hand, the air cylinder 7 has two pistons 8 and 9 linked in series from the axial direction in the cylinder 7a, and supplies and discharges air to and from the pressure receiving chambers 7b and 7c at the rear of the pistons 8 and 9. 10 is provided.

During normal operation when the accelerator pedal is depressed, the air circuit 10 does not operate and each pressure receiving chamber 7 does not operate.
No air is supplied into b and 7c, the pistons 8 and 9 are urged to the retracted position by the spring force of the spring 11, and the tapered block 6 is also held at the retracted position. Accordingly, the power tard valve 1 is closed.

When the accelerator pedal is turned off and a compression brake operation signal is output from the controller 12 by a manual operation of the driver, the air circuit 10 sends the signal to the first pressure receiving chamber 7b or the second pressure receiving chamber 7c according to the vehicle speed. Air is supplied.

That is, at low speed, air is supplied to the first pressure receiving chamber 7b via the pump 13, and the first piston 8 and the second piston 9 are driven to the first forward position (the first fixed stopper 14). The taper block 6 moves from the first opening adjustment surface 6a to the second opening adjustment surface 6b via the taper surface. As a result, the power tard valve 1 gradually opens to a small valve lift opening amount. As a result, a small amount of exhaust is performed, and a braking force corresponding to low-speed operation is obtained.

On the other hand, at high speed, air is also supplied to the second pressure receiving chamber 7c by the air circuit 10, so that the second piston 9 separates from the first piston 8 and further moves to the second forward position (second position).
The tapered block 6 is driven to the fixed stopper 15), and moves to the third opening adjustment surface 6c. As a result, the power tard valve 1 is gradually further opened to a large valve lift opening amount. As a result, a relatively large amount of exhaust is performed, and a braking force corresponding to high-speed operation is obtained.

[0011]

However, in the conventional engine brake device, the opening / closing drive mechanism 2
The variable lift mechanism is mainly composed of a tapered block 6 extending long in the front-rear direction and two first and second pistons 8 and 9 arranged in series at the longitudinal position of the tapered block 6. Therefore, the lengths of the opening / closing drive mechanism and the lift variable mechanism including the block 3 and the air cylinder 7 are increased, and the size and weight are inevitably increased. As a result, the mountability on the engine deteriorates.

Further, since two relatively large pistons 8 and 9 having the same diameter are used, air is relatively supplied to the respective pressure receiving chambers 7b and 7c via the air circuit 10. In addition, the structure becomes complicated, the manufacturing operation efficiency is reduced, and the cost is increased.

[0013]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional problems.
A drive means for opening and closing an exhaust valve of an engine by advancing and retreating a piston sliding in a cylinder; and a variable means provided in the drive means for regulating a movement position of the piston and varying a lift amount of the exhaust valve. The variable means includes a stopper member for regulating a maximum advance position of the piston, and a stopper mechanism for extending and retracting in the cylinder to regulate an intermediate advance position of the piston. It is characterized by.

According to a second aspect of the present invention, the driving means includes:
A hydraulic circuit for supplying and discharging hydraulic pressure to the cylinder to move the piston forward and backward is provided, and a check valve for supplying hydraulic pressure only in the cylinder direction is provided in a supply passage of the hydraulic circuit,
A free piston is provided which opens and closes a discharge passage for discharging the hydraulic pressure in the cylinder in accordance with a signal oil pressure in a supply passage.

According to a third aspect of the present invention, the stopper mechanism includes a sliding hole formed in a circumferential wall of the cylinder along a radial direction of the cylinder, and the stopper mechanism is slidably housed in the sliding hole. It is characterized in that a plunger having a stopper pin at the tip protrudes and retracts in the cylinder, and a hydraulic passage for supplying and discharging hydraulic pressure to the oil chamber in the sliding hole to operate the plunger.

According to a fourth aspect of the present invention, the driving means includes:
A rocker arm having one end pressing down the end of the exhaust valve, a rocker shaft rotatably supporting the other end of the rocker arm via a cam ring, one end connected to the rocker shaft, and the other end being the piston And a lever portion linked to the piston rod.

According to the present invention, the valve lift of the exhaust valve can be made variable by the variable means according to, for example, the engine speed.
The linear motion of the two pistons is converted into a rotary motion via a lever portion, a cam ring, and the like to open and close the exhaust valve, and the variable means particularly adjusts the advance stroke position of the piston into and out of the cylinder of the stopper mechanism. Therefore, the valve lift can be varied by one piston.

[0018]

FIG. 1 shows a first embodiment of an engine brake system according to the present invention. In FIG. 1, reference numeral 21 denotes an exhaust valve for opening and closing an exhaust port E formed in a cylinder head S of the engine. Driving means 23 for opening and closing the exhaust valve 21 is a variable means provided in the driving means 22 for varying the lift amount of the exhaust valve 21.

The exhaust valve 21 is slidably guided by a tubular stem guide (not shown) in which a stem 21a is fixed to the cylinder head S.

The drive means 22 includes a rocker shaft 24 extending along the longitudinal direction above the cylinder head S.
And one end 25a is rotatably supported by the rocker shaft 24 via a cam ring 26, and the other end 25b is disposed on the rocker arm 25 pressing the upper end of the stem 21a, and on the side of the rocker arm 25. One end 27a includes a lever 27 fixed to the rocker shaft 24, and an actuator 29 for pushing up and operating the other bent end 27b of the lever 27.

The actuator 29 is shown in FIGS.
As shown in FIG. 4, a body 30 bolted to the upper end of the cylinder head S and a cylinder 31 formed in a cylindrical cylinder wall 30b constituting a part of the body 30 are slidable up and down. And a hydraulic circuit 34 for supplying and discharging hydraulic pressure to a hydraulic chamber 33 located below the cylinder 31 to move the piston 32 forward and backward.

The body 30 has a flat base portion 30.
a, the cylinder wall 30b is erected on
A cylindrical boss portion 30c is integrally fixed to the side of the cylinder wall 30b along the horizontal direction.

The cylinder 31 is provided with a lower hydraulic chamber 33.
Is closed by a bottom wall 30d, while the upper end is formed with an opening, and the upper part of the opening is closed by a stopper member 46 described later. Further, the piston 32
Has a seal ring 35 fitted around the outer periphery,
At the center of the upper surface, a piston rod 32a that abuts on the lower surface of the other end portion 27b of the lever portion 27 is integrally erected.

As shown in FIG. 1, the hydraulic circuit 34 includes a supply passage 36 formed in the cylinder head S and a cylinder block (not shown), and a hydraulic chamber 3 formed in the bottom wall 30d.
3, a discharge passage 37 for discharging the hydraulic pressure in the outside, an oil pump 38 provided at an upstream end of the supply passage 36, and a three-way first solenoid valve 39 provided downstream of the oil pump 38. It has.

In the supply passage 36, the base 3
0a and a vertical hole 3 formed in the bottom wall 30d in a substantially crank-shaped manner and formed in the base portion 30a in a vertical direction.
6a, a horizontal passage 36b extending horizontally from the upper end of the vertical hole 36a, and a downstream end 36c of the horizontal passage 36b.
And a vertical passage portion 36d extending vertically upward in the bottom wall 30d and communicating with the hydraulic chamber 33.

A check valve 40 for circulating the hydraulic pressure only in the direction of the hydraulic chamber 33 is provided in a large-diameter hole provided at the upper end of the vertical passage portion 36d.
Reference numeral 0 denotes a check ball 40a that opens and closes the open end of the vertical passage portion 36d, and a check spring 40c that has one end elastically held by the retainer 40b and urges the check ball 40a in the closing direction.

A free piston 42 for opening and closing the discharge passage 37 is vertically slidable in a piston hole 41 formed in parallel with a side of the vertical passage portion 36d. The piston hole 41 communicates with the downstream end 36c of the horizontal passage portion 36b so that the free piston 42 is slid in the vertical direction, that is, in the opening and closing direction by the signal oil pressure from the supply passage 36.

The free piston 42 has an upper end 42a formed in a truncated conical shape, and has a tapered upper peripheral surface for opening and closing a through hole 37a formed in the upper wall of the piston hole 41. The maximum lowering position is regulated by a plug 43 closing the lower opening of the piston hole 41.

The first solenoid valve 39 includes a controller 44
Accordingly, the supply passage 36 and the first drain passage 45 are appropriately switched to operate, and the controller 44 outputs a switching signal to the first solenoid valve 39 in accordance with the engine speed detected by the crank angle sensor. I have.

On the other hand, the variable means 23 is provided in FIG.
The stopper member 46 is provided above the opening of the cylinder 31 and regulates the maximum advance position of the piston 32, and the stopper is formed in the cylinder 31 from the radial direction to regulate the intermediate movement position of the piston 32. And a mechanism 47.

The stopper member 46 has a substantially T-shaped cross section, has a flange portion fixed to the inner peripheral surface of the cylinder 31 via a stopper ring 48, and is integrally provided on the lower surface at the center of the flange portion. A cylindrical portion 46a that slides and guides the piston rod 32a is provided. The inner periphery of the upper surface of the piston 32 abuts on the lower end edge of the cylindrical portion 46a to restrict upward movement of a predetermined amount or more.

The stopper mechanism 47 has a cylindrical sliding hole 49 formed in the boss 30c along the horizontal direction.
, A plunger 50 that slides in the sliding hole 49, and a hydraulic passage 52 that supplies and discharges hydraulic pressure to an oil chamber 51 formed on the front end side of the plunger 50. The plunger 50 is integrally provided with a stopper pin 50a that protrudes into and out of the cylinder 31 from a through hole 53 formed in the cylinder wall 30b at the center of the distal end surface, and closes a rear end opening of the sliding hole 49. It is urged in the advance direction by a spring 55 held by the plug 54. Further, an annular seal for sealing the inside of the oil chamber 51 is fitted and fixed to the outer peripheral surface of the plunger 50.

The hydraulic passage 52 has an upstream end connected to the oil pump 38 via a three-way second solenoid valve 56 as shown in the figure, and a downstream end communicating with the oil chamber 51. I have. The second solenoid valve 56 switches between the hydraulic passage 52 and the second drain passage 57 in response to a switching signal from the controller 44, similarly to the first solenoid valve 39.

The rocker arm 25 swings by receiving a cam lift force of a cam via a valve lifter and a push rod (not shown) to open and close the exhaust valve 21.

The operation of this embodiment will be described below.
First, during normal operation with the accelerator pedal depressed, the controller 44 sends the first and second solenoid valves 39, 56
Control signals are output to the respective drain passages 45 and 57.
Is switched to open. Therefore, as shown in FIG. 1, the hydraulic pressure fed from the oil pump 38 is discharged from the drain passages 45 and 57, and no hydraulic pressure is supplied to the hydraulic chamber 33 and the oil chamber 51.
Is kept closed. Therefore, no braking force of the engine brake is generated.

Next, when the driver depresses the accelerator pedal in the low-medium rotation range of the engine and operates the engine brake by the driver, as shown in FIG. A switching signal is output to only one solenoid valve 39 and the drain passage 45
To the supply passage 36. Accordingly, the plunger 50 is maintained in the advanced state by the spring force of the spring 55, and the stopper pin 50a is in a state of protruding into the cylinder 31. On the other hand, the hydraulic pressure fed from the oil pump 38 passes through the supply passage 36 The check ball 40a is supplied into the hydraulic chamber 33 while being pushed open.
At the same time, a signal oil pressure is supplied from the horizontal passage portion 36b to the piston hole 41, the large-diameter lower pressure receiving surface is pushed, the free piston 42 moves upward, and the through hole 37a is closed on the upper peripheral surface.

Therefore, the piston 32 is
Is moved upward by the hydraulic pressure inside the stopper pin 50a.
Further upward movement is restricted at the position where
It is held at a predetermined intermediate position.

For this reason, as the piston rod 32a advances to the intermediate position, the lever portion 27 rotates by a predetermined amount to swing the other end portion 25b of the rocker arm 25 downward through the cam ring 36, and thereby the exhaust valve 21 is opened with a slight opening X as shown. Therefore, an optimal braking force by the engine according to the low to middle rotation range can be obtained.

On the other hand, when the engine brake operation is performed in the high speed range, a switching signal is also output from the controller 47 to the second solenoid valve 56 during the compression and expansion strokes of the engine as shown in FIG. The hydraulic passage 52 is switched from the second drain passage 57 to the hydraulic passage 52.
Is supplied to the oil chamber 51 from the oil pressure. Accordingly, the plunger 50 moves backward against the spring force of the spring 55, and the stopper pin 50a moves backward into the through hole 53. Therefore, the piston 32 is allowed to further move upward and moves up until the upper surface contacts the lower end edge of the cylindrical portion 46 a of the stopper member 46.

For this reason, the lever 27, the cam ring 2
6, the exhaust valve 21 is further opened via the rocker arm 25 to have a relatively large opening amount Y. Therefore, an optimal braking force by the engine according to the high rotation range can be obtained.

Further, when shifting from the high speed range to the low / medium speed range, a switching signal is output to the first solenoid valve 39 once, the first drain passage 45 is opened, and the supply of the hydraulic pressure to the hydraulic chamber 33 is performed. Stopped. Then, the signal oil pressure from the horizontal passage portion 36b to the piston hole 41 is also stopped, the oil pressure in the piston hole 41 decreases, and the free piston 42 descends to open the through hole 37a. Therefore, the oil pressure in the hydraulic chamber 51 is returned to the oil pan through the discharge passage 37 including the through hole 37a, whereby the oil pressure in the hydraulic chamber 33 decreases and the piston 32 descends.

At this point, since the high pressure is maintained in the oil chamber 51 via the second solenoid valve 56, the stopper pin 5
0a is a state in which the piston 3 is retracted into the through hole 53, and the piston 3
2 downward movement is allowed.

Then, the piston 32 descends and the through hole 5
When passing through the front of the stopper pin 50a existing in the third, a switching signal is simultaneously output to the first and second solenoid valves 39 and 56, the hydraulic pressure is again supplied into the hydraulic chamber 33, and the second drain passage 57 is opened. Then, the oil pressure in the oil chamber 51 is discharged. Therefore, as shown in FIG.
Rises, the plunger 50 advances, and the stopper pin 50a protrudes into the cylinder 31, restricting the piston 32 from further ascending and holding it at the intermediate position. As a result, the exhaust valve 21 is held at the slight opening amount shown in FIG. 3, and the optimum braking force in the low-to-medium rotation region can be secured.

When the engine brake is released, a switching signal is output to the first solenoid valve 39, and the hydraulic pressure in the hydraulic chamber 33 is discharged from the discharge passage 37 to a low pressure. As shown, it moves to the lowest position to close the exhaust valve 21.

As described above, in this embodiment, the variable means 23 can variably control the braking force of the engine brake in three stages with high accuracy in accordance with the engine speed. Moreover, the driving means 2
2 converts the linear motion of the piston 32 into a rotary motion via the rocker arm 25, the cam ring 26, and the lever portion 27, so that the entire configuration of the driving means 22 becomes compact.

Also, as for the variable means 23, a double piston is provided in series as in the prior art, and the movement of each piston is restricted by fixed front and rear stoppers. In particular, since the stopper pin 50a of the stopper mechanism 47 can be arbitrarily converted by the action of the stopper pin 50a protruding and retracting into the cylinder 31, the structure of the variable means 47 can be simplified and made compact.

In addition, when the engine brake is released or the like, the holding and discharging of the hydraulic pressure in the hydraulic chamber 33 is performed by the free piston 42 which is opened and closed by the signal hydraulic pressure, so that high hydraulic pressure retaining and hydraulic discharging properties can be obtained.
That is, the free piston 42 can obtain high hydraulic pressure retention with a low supply hydraulic pressure (signal hydraulic pressure) by giving an optimal ratio to the upper and lower pressure receiving areas. On the other hand, when the supply hydraulic pressure (signal hydraulic pressure) is cut, the free piston 4
2 is lowered and the hydraulic pressure is discharged from the through hole 37a, so that the hydraulic discharge performance, that is, the responsiveness is greatly improved. Further, since the through hole 37a is closed by the tapered surface of the upper end 42a of the free piston 42, a stable sealing property is obtained.
Furthermore, since the inside of the hydraulic chamber 33 is sealed by the check valve 40 in addition to the free piston 42 having a high receiving pressure, the hydraulic pressure retention is further promoted.

FIG. 5 shows a second embodiment of the present invention. In this embodiment, a valve hole 60 is formed in a horizontal passage portion 36b of a supply passage 36, and a spool valve 61 and a check valve 62 are provided in the valve hole 60. The free piston of the first embodiment is eliminated by assembling. More specifically, the valve hole 60 is formed in the base portion 30a, and the front end portion is formed in the horizontal passage portion 36b.
And an upper portion thereof communicates with the hydraulic chamber 33 through a vertical passage portion 36d. A bolt-shaped spring receiving portion 63 is press-fitted and fixed to the rear end of the valve hole 60, and a discharge passage 37 is formed through the rear portion of the spring receiving portion 63. Further, the spring receiving portion 6
3 communicates with the discharge passage 37 via a through passage 63a formed through the center.

The spool valve 61 sliding in the valve hole 60
An annular groove 64 is formed on the outer periphery, and a communication hole 65 communicating the inside with the annular groove 64 is formed in the peripheral wall in the radial direction. The spool valve 61 has a passage hole 66 formed in the center of the front end wall and a valve spring 67 elastically held between the front end wall and the rear end flange of the spring receiving portion 63, that is, a vertical passage portion 36d. And valve hole 6
It is urged to a position that communicates with zero. Further, the inside of the spool valve 61 is liquid-tightly sealed by a rear end plate 68.

The check valve 62 is housed inside the spool valve 61, and the check ball 62a is
b is biased in a direction to close the passage hole 66 by the spring force of the spring 62c held between the spring 62b and the spring b.

The structure of the stopper mechanism 47 of the variable means 23 and the hydraulic circuit 34 are the same as those of the first embodiment. Therefore, according to this embodiment, during normal operation, since the solenoid valves 39 and 56 open the drain passages 45 and 57 by the controller as in the first embodiment, as shown in FIG. The oil pressure is not supplied to the oil chamber 51, the piston 32 is held at the lowest position, and the stopper pin 50a also projects into the cylinder 31. Therefore, no braking force of the engine brake is generated.

When the engine brake device is operated in the low / medium rotation range, a switching signal is output only to the first solenoid valve 39, hydraulic pressure flows into the supply passage 36, and acts on the valve hole 60. As shown in FIG. 6, the spool valve 61 is retracted against the spring force of the valve spring 67 so that the annular groove 64 communicates with the vertical passage 36d, and at the same time, the check ball 62a also resists the spring force of the spring 62c. To open the passage hole 66. For this reason, the hydraulic pressure flowing into the valve hole 60 is supplied to the hydraulic chamber 33 through the passage hole 66, the inside of the spool valve 61, the communication hole 65, the annular groove 64, and the vertical passage portion 36d. Therefore, the piston 32
Rises until it hits the stopper pin 50a. As a result, the exhaust valve 21 is slightly opened via a lever unit, a rocker arm, and the like (not shown) to generate an engine brake corresponding to the low and middle rotation range.

When the engine brake device is operated in the high speed range, a switching signal is also output to the second solenoid valve 56, as shown in FIG. The plunger 50 is retracted to move the stopper pin 50 into the through hole 53. Therefore, the piston 32 further moves upward, hits the lower end edge of the cylindrical portion 46a of the stopper member 46, and is held at the maximum raised position. Thereby, the exhaust valve 21
Relatively wide open to generate a braking force suitable for a high rotation range during the compression and expansion strokes.

Next, when shifting from the high speed range to the low / medium speed range, a switching signal is output to the first and second solenoid valves 39 and 56 once. The vertical passage portion 3 is moved forward by the spring force.
6d communicates with the valve hole 60. Therefore, the hydraulic pressure in the hydraulic chamber 33 is returned from the valve hole 60 to the oil pan through the through passage 63a and the discharge passage 37. Therefore, piston 3
2, the switching signal is output to each of the solenoid valves 39 and 56 immediately after that, hydraulic pressure is supplied to the hydraulic chamber 33 and the oil chamber 51, and the plunger 50 advances as shown in FIG. , And rises until the piston 32 hits the stopper pin 50a, and is held at the intermediate position. As a result, the exhaust valve 21 is slightly opened in the same manner as described above to generate an optimal braking force.

As described above, in this embodiment, the driving means 22
In addition to the fact that the optimum braking force corresponding to the engine speed can be obtained by the variable means 23 and the variable means 23, the spool valve 61 and the check valve 62 are combined, so that the structure can be made compact.

The present invention is not limited to the configuration of the above embodiment.

[0057]

As is apparent from the above description, according to the engine brake device of the present invention, it is possible to obtain an optimal and high-precision braking force in accordance with the engine speed, as well as the overall device. The structure can be simplified and made compact.
As a result, the mountability on the engine is improved.

Further, according to the second aspect of the present invention, since the holding and discharging of the hydraulic pressure in the hydraulic chamber is performed by using the free piston, a high hydraulic pressure retaining property and a high hydraulic pressure discharging response can be obtained.

According to the third aspect of the present invention, the sliding position of the piston can be reliably regulated, and the regulation control accuracy can be improved.

Further, according to the fourth aspect of the present invention, the driving means can be made compact.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an engine brake device showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a part of a driving mechanism provided in the embodiment.

FIG. 3 is a longitudinal sectional view of an apparatus showing the operation of the present embodiment.

FIG. 4 is a longitudinal sectional view of an apparatus showing the operation of the present embodiment.

FIG. 5 is a longitudinal sectional view of an apparatus showing a second embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of an apparatus showing the operation of the present embodiment.

FIG. 7 is a longitudinal sectional view of an apparatus showing the operation of the present embodiment.

FIG. 8 is a longitudinal sectional view showing a conventional engine brake device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Exhaust valve 22 ... Driving means 23 ... Variable means 24 ... Rocker shaft 25 ... Rocker arm 26 ... Cam ring 27 ... Lever part 30 ... Body 31 ... Cylinder 32 ... Piston 33 ... Hydraulic chamber 34 ... Hydraulic circuit 36 ... Supply passage 37 ... Discharge Passages 40, 62 Check valve 42 Free piston 46 Stopper member 47 Stopper mechanism 50 Plunger 50a Stopper pin 51 Oil chamber 52 Hydraulic passage

Claims (4)

[Claims] 1. A drive means for opening and closing an exhaust valve of an engine by advancing and retreating a piston sliding in a cylinder, and a lift amount of the exhaust valve provided in the drive means for regulating a moving position of the piston. An engine brake device comprising: a stopper member that regulates a maximum advance position of the piston; and a stopper mechanism that regulates an intermediate advance position of the piston by moving in and out of the cylinder. An engine brake device comprising: 2. The drive means includes a hydraulic circuit for supplying and discharging hydraulic pressure to and from the cylinder to move the piston forward and backward, and a check valve for supplying hydraulic pressure only in the cylinder direction to a supply passage of the hydraulic circuit. A free piston that opens and closes a discharge passage for discharging oil pressure in the cylinder in accordance with a signal oil pressure in a supply passage.
The described engine brake device. 3. The stopper mechanism includes a sliding hole formed in a circumferential wall of the cylinder along a radial direction of the cylinder.
The plunger is slidably housed in the sliding hole, and the stopper pin at the tip projects in and out of the cylinder, and a hydraulic passage for supplying and discharging hydraulic pressure to the oil chamber in the sliding hole to operate the plunger. The engine brake device according to claim 1 or 2, further comprising: 4. The rocker arm having one end for pushing down an end of an exhaust valve, a rocker shaft for rotatably supporting the other end of the rocker arm via a cam ring, and one end for the rocker shaft. 4. The engine brake device according to claim 3, further comprising a lever connected to the other end of the piston and connected to a piston rod of the piston.