JP2001234723A - Actuator of engine brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve exhaust performance and stabilize engine rotation by heightening oil pressure discharge efficiency from an oil pressure chamber to the outside, and obtaining high lowering speed of a piston to secure favorable operation release responsiveness of an engine brake. SOLUTION: This actuator is provided with a cylinder 31 containing a piston 32 interlocking with an exhaust valve 21 in the interior, a hydraulic circuit 34 for supplying and discharging oil pressure to and from hydraulic chamber 33 of the cylinder through a supply passage 36 and a discharge passage 37 to slide the piston, and a valve mechanism 29 for controlling the discharge passage to be opened and closed. A bypass passage 50 bypassing the discharge passage and bent substantially L-shaped is separately provided to increase the whole passage sectional area, and both passage are opened by a free piston 42 to efficiently discharge oil pressure in the hydraulic chamber to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for 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, one described in Japanese Patent Application Laid-Open No. 7-259589 is known.

[0005] Referring to FIGS. 5 and 6, a rocker arm 1 for opening and closing an exhaust valve 2 is supported by a rocker shaft 4 via an eccentric bush 3.

The eccentric bush 3 is provided with a hydraulic actuator 5 disposed in a rocker cover of the cylinder head S.
When the piston rod 6a of the hydraulic actuator 5 extends upward due to the rise of the piston 6, the rotation center of the rocker arm 1 is lowered and the exhaust valve 2 is opened by a predetermined lift amount. Has become. The hydraulic actuator 5 is connected to an oil pump 8 via a hydraulic supply passage 7 having a branch passage and a merging passage (not shown), and an electromagnetic valve 9 for operating pressure is interposed in the middle of these passages.

The solenoid valve 9 is controlled by a controller 10 to supply hydraulic pressure from the oil pump 8 to each hydraulic actuator 5 when a brake is operated, and when the brake is released, the rocker arm 1 and the eccentric bush 3 return to the initial position. The hydraulic pressure in the hydraulic actuator 5 is released to the oil pan side so as to be returned.

As shown in FIG. 6, the hydraulic actuator 5 has a hydraulic chamber A separated below a piston 6 slidably housed in a cylinder 5a. And a hydraulic introduction passage 13 provided with a check valve 11 that allows only supply of hydraulic pressure to the hydraulic chamber A.
And a discharge passage 14 for releasing the hydraulic pressure in the hydraulic chamber A to the low pressure side.
A valve mechanism 15 for controlling the opening and closing of the valve is provided.

The discharge passage 14 includes a discharge hole 14a for communicating the hydraulic chamber A with a piston hole 16 described later, and a discharge passage 14b formed substantially horizontally through an outer wall of the piston hole 16. I have.

The valve mechanism 15 includes a piston hole 16 formed in parallel with the hydraulic pressure introduction path 13, and a free piston 17 slidably provided in the piston hole 16.
The free piston 17 has a hydraulic pressure introduced into the upper part of the piston hole 16 from the hydraulic chamber A through the discharge hole 14a, and a piston hole 16 from the hydraulic pressure supply passage 7 through the communication passage 18. The communication between the discharge hole 14a and the discharge path 14b is established or interrupted by a pressure difference between the hydraulic pressure introduced into the lower part and the discharge hole 14a.

When the pressure difference between the hydraulic chamber A and the hydraulic pressure supply passage 7 becomes larger than a predetermined value, the free piston 17 moves downward to release the discharge hole 14a and the discharge passage 14b.
And the operating oil in the hydraulic chamber A is discharged to the oil pan to be in a low pressure state.

Therefore, when the operating oil pressure is supplied from the oil pump 8 via the solenoid valve 9, this pressure becomes
The check valve 11 is opened, and the hydraulic chamber A is
Supplied to At this time, the pressure acting on the upper surface of the free piston 17 of the valve mechanism 15 is higher than the pressure acting on the lower surface, so that the discharge hole 14a is kept closed. Thus, the pressure rises in the hydraulic chamber A, the piston 6 rises, and the exhaust valve 2 is slightly opened to function as an engine brake.

On the other hand, when the electromagnetic valve 9 is closed and the supply of hydraulic pressure from the oil pump 8 is stopped, the pressure on the hydraulic supply passage 7 decreases, and when the reaction force of the valve train acts, , The load in the compression direction acts on the piston 6 and the hydraulic chamber A
Side rises relatively, the free piston 17
Moves downward to open the discharge path 14b. This allows
The hydraulic pressure in the hydraulic chamber A flows from the discharge hole 14a to the discharge path 14b to be in a low pressure state. As a result, the piston 6 is lowered, the exhaust valve 2 is closed, and the function as the engine brake is released.

[0012]

By the way, in this engine brake device, the size of the actuator 5, that is, the capacity of the cylinder 5a is made different depending on the size of the engine on which the engine brake device is mounted. However, since the capacity of the internal hydraulic pressure increases as the volume of the cylinder 5a increases, the speed at which the cylinder 5a is discharged to the outside via the discharge passage 14 when the operation of the engine brake is released is reduced. .

Similarly, when the input load in the compression direction acting on the piston 6 from the valve train of the engine at the time of releasing the operation of the engine brake is small, the cylinder 5a
There is a tendency that the discharge speed in the inside becomes slow.

As a result, the response to release of the engine brake is deteriorated, and the closing operation of the exhaust valve 2 immediately after the release of the operation is slowed down, so that the exhaust emission performance may be reduced.

In particular, since the discharge hole 14a of the discharge passage 14 has a relatively small cross-sectional area, the discharge hole 14a deteriorates the efficiency of discharging the hydraulic pressure in the cylinder 5a.

[0016]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned conventional problems, and the invention according to claim 1 has a piston connected to an exhaust valve of an engine, and the piston is provided inside the piston. A cylinder slidably accommodated in the cylinder, a hydraulic circuit that slides the piston by supplying and discharging hydraulic pressure to and from a hydraulic chamber in the cylinder through a supply passage and a discharge passage, and slides in the piston hole. An actuator of an engine brake device including a valve mechanism that freely opens and closes the discharge passage in accordance with a pressure difference between a hydraulic pressure in the hydraulic chamber and a hydraulic pressure flowing in a supply passage.
A bypass passage that bypasses the discharge passage and discharges the hydraulic pressure in the hydraulic chamber to the outside is provided.

Therefore, according to the present invention, when the operation of the engine brake is released, first, the supply of the hydraulic pressure to the supply passage is cut off, and the pressure receiving chamber below the free piston communicating with the supply passage has a low pressure. On the other hand, the pressure in the hydraulic chamber becomes relatively high due to the pressure in the compression direction from the valve train. The differential pressure between the two hydraulic pressures causes the free piston to move downward to open the discharge passage, and the free passage also causes the bypass passage to open. Therefore, the hydraulic pressure (hydraulic oil) in the hydraulic chamber is quickly discharged to the outside through both the discharge passage and the bypass passage. For this reason, the response to release of the engine brake operation is improved.

According to a second aspect of the present invention, the bypass passage is formed so as to cross the piston hole from the hydraulic chamber substantially in the radial direction, and the opening end of the bypass passage is slid to the sliding position of the free piston. The opening / closing control is performed according to the following.

According to a third aspect of the present invention, the discharge passage extends through an upper wall of the piston hole and communicates with the hydraulic chamber and the piston hole. The bypass passage is formed substantially in the side wall of the piston hole, and has an upstream portion opened at a substantially central position of the hydraulic chamber. It is characterized in that a piston hole is formed in the horizontal downstream portion so as to penetrate the piston hole in the diametrical direction.

According to a fourth aspect of the present invention, a groove is formed in the outer periphery of the free piston so as to coincide with the opening end of the bypass passage at a predetermined downward movement position of the free piston.

According to a fifth aspect of the present invention, there is provided a piston linked to an exhaust valve of an engine, a cylinder in which the piston is slidably housed, and a supply passage and a discharge passage for a hydraulic chamber in the cylinder. And a hydraulic circuit that slides the piston by supplying and discharging hydraulic pressure via a hydraulic pump, and a difference between the hydraulic pressure in the hydraulic chamber and the hydraulic pressure flowing through the supply passage between the free piston slidably provided in the piston hole. An actuator for an engine brake device having a valve mechanism for controlling the opening and closing of the discharge passage in accordance with a pressure, wherein a spring member for urging the free piston in a direction to close the discharge hole is provided below the piston hole. It is characterized by that.

[0022]

FIG. 1 shows an embodiment of an actuator of an engine brake device according to the first aspect of the present invention.

First, the overall structure of the engine brake device will be briefly described. An exhaust valve 21 for opening and closing an exhaust port formed in a cylinder head S of an engine, and a driving means 22 for opening and closing the exhaust valve 21 are provided. ing.

The exhaust valve 21 has a valve stem slidably guided by a cylindrical stem guide (not shown) fixed to the cylinder head S, and an umbrella portion below the valve stem has an exhaust port opening. The valve seat provided at the end is detached and seated to open and close the open end.

The drive means 22 includes a rocker shaft 24 extending longitudinally above the cylinder head S.
And a rocker arm 25 that is rotatably supported at one end 25a side by a rocker shaft 24 via an eccentric bush 26, and the other end 25b presses the upper end of the valve stem of the exhaust valve 21, and a side of the rocker arm 25. The lever 27 includes one end 27a fixed to the rocker shaft 24 and one end 27a fixed to the rocker shaft 24, and an actuator 28 that pushes up the other bent end 27b of the lever 27. The rocker arm 25 is configured to swing by a drive cam 23 linked to one end 25a via a push rod 23a.

The actuator 28 is shown in FIGS.
As shown in the figure, a body 30 fixed to the upper end of the cylinder head S by bolts, a cylinder 31 formed in a cylindrical cylinder wall 30b constituting a part of the body 30, and a vertical A hydraulic circuit 34 for supplying and discharging hydraulic pressure to a piston 32 housed slidably and a hydraulic chamber 33 located below the cylinder 31 to move the piston 32 forward and backward.
And a valve mechanism 29 for controlling opening and closing of a later-described discharge passage 37 of the hydraulic circuit 34.

The body 30 has a flat base portion 30.
The cylinder wall 30b is erected on the cylinder wall 30a, and the cylinder 31 in the cylinder wall 30b has a lower hydraulic chamber 33 closed, while an upper end formed with an opening is closed by a stopper member 46. ing. Further, the piston 32 has a seal ring fitted on the outer periphery thereof, and a piston rod 32a which is engaged with the other end portion 27b of the lever portion 27 via a pin 35 at the center of the upper surface and is integrally provided upright. .

The hydraulic circuit 34 includes a supply passage 36 formed in the cylinder head S and a cylinder block (not shown) as shown in FIG. 1, and a hydraulic passage 33 formed in the lower wall of the body 30 and in the hydraulic chamber 33. , An oil pump 38 provided at the upstream end of the supply passage 36, and a two-way solenoid valve 39 provided downstream of the oil pump 38. Have. In the lower wall of the body 30, there is formed a bypass passage 50 that bypasses the discharge passage 37 and discharges the oil pressure in the hydraulic chamber 33 to the oil pan.

The supply passage 36 has a base portion 3 on the downstream side.
0a and a vertical hole 36 formed substantially in the shape of a crank inside the lower wall and bored vertically in the base portion 30a.
a, and a horizontal passage portion 3 extending horizontally from the vertical hole 36a.
6b and a vertical passage portion 36c extending vertically upward in the lower wall from the vertical hole 36a and communicating with the hydraulic chamber 33.

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

The discharge passage 37 is formed through the lower part of the body 30 in the vertical direction, and communicates with a hydraulic chamber 33 and an oil chamber 41a provided above a piston hole 41 described later. An oil passage 41b is formed substantially at the upper part of the side wall of the piston hole 41 along the horizontal direction and communicates the oil chamber 41a with an oil pan (not shown). The discharge hole 37a has a passage cross-sectional area set relatively small so as to introduce pilot pressure into the oil chamber 41a.

The bypass passage 50 is formed in a substantially L-shape in the lower wall of the body 30, and the upstream opening end of the vertical upstream portion 50 a is formed at the center of the bottom surface of the hydraulic chamber 33. On the other hand, a horizontal downstream portion 50b, which crosses substantially the center of the piston hole 41, has a downstream open end formed on the outer surface of the body 30, and communicates therefrom with an oil pan (not shown). The downstream portion 50b is connected to the discharge path 3
7b are formed in parallel at the lower part. Further, the cross-sectional area of the bypass passage 50 is formed to have a relatively large uniform diameter, and the discharge hole 37a of the discharge passage 37 and the discharge passage 3 are formed.
7b.

The valve mechanism 29 has a piston hole 41 formed vertically in a boss portion provided on the side of the vertical passage portion 36d, and a free piston 42 housed in the piston hole 41 so as to be vertically slidable. It is mainly composed of

The piston hole 41 is formed in the lower wall portion of the body 30 so as to vertically penetrate therethrough. The upper oil chamber 41a communicates with the hydraulic chamber 33 through the aforementioned discharge hole 37a, The pressure receiving chamber 41b communicates with the horizontal passage portion 36b.

The free piston 42 has an upper end 42a.
Is formed in a truncated conical shape, and the oil pressure in the hydraulic chamber 33 acts as pilot pressure from the discharge hole 37a on the flat upper surface and the tapered upper peripheral surface of the upper end portion 42a. Open end 50 whose outer peripheral surface of the cylindrical portion 42b faces substantially the center of the piston hole 41 in the vertical direction.
c is controlled to open and close. The free piston 42 is connected to a signal oil pressure supplied / discharged from the supply passage 36 into the pressure receiving chamber 41b, and from the discharge hole 37a to the oil chamber 4
A plug 43 for closing the lower opening of the piston hole 41 in the vertical direction, that is, the opening end of the discharge hole 37a, by a differential pressure from the pilot pressure supplied to the inside of the piston hole 41a.
The opening end 50c is maximally opened by the outer peripheral surface of the upper end portion 42a at the maximum lowering position where the upper end portion 42a abuts.

The solenoid valve 39 is adapted to appropriately switch the supply passage 36 and the drain passage 45 by a controller 44. The controller 44 operates the solenoid valve 39 according to the engine speed detected by a crank angle sensor. Output the switching signal.

The operation of this embodiment will be described below.
First, during a normal operation in which the accelerator pedal is depressed, a control signal is output from the controller 44 to the solenoid valve 39, and switching is performed so as to open the drain passage 45. Accordingly, the hydraulic pressure fed from the oil pump 38 is discharged from the drain passage 45 and the hydraulic pressure is not supplied to the hydraulic chamber 33, so that the exhaust valve 21 opens and closes normally according to the lift of the drive cam 23. The operation is performed, and the braking force of the engine brake is not generated.

Next, when the depression of the accelerator pedal is released during normal operation of the vehicle and the engine brake is operated, a switching signal is output from the controller 44 to the solenoid valve 39, and the switching signal is output from the drain passage 45 to the supply passage 36. Can be switched. Therefore, the hydraulic pressure pumped from the oil pump 38 passes through the supply passage 36 to the check ball 40a.
While being opened, is supplied into the hydraulic chamber 33. At the same time, the pressure receiving chamber 41 of the piston hole 41 extends from the horizontal passage portion 36b.
The signal hydraulic pressure is supplied to b, the lower pressure receiving surface of the free piston 42 is pressed, and the free piston 42 moves upward to close the lower end opening of the discharge hole 37a at the upper surface of the upper end portion 42a.

Therefore, as shown in FIG. 2, the piston 32 moves upward due to the rising hydraulic pressure in the hydraulic chamber 33, and further upward movement is restricted at a position where the upper surface abuts against the stopper member 46. Is held.

For this reason, the lever portion 27 rotates by a predetermined amount in accordance with the upward stroke movement of the piston rod 32a, and the other end 2 of the rocker arm 25 passes through the eccentric bush 26.
5b is swung downward, whereby the exhaust valve 21 is opened with a predetermined opening amount. Therefore, an optimal braking force by the engine can be obtained.

Next, when the operation of the engine brake is released, a switching signal is output to the solenoid valve 39, and the hydraulic oil in the supply passage 36 is discharged from the drain hole 45 of the solenoid valve 39, so that the pressure receiving chamber 41b Becomes low pressure state. Accordingly, the free piston 42 moves down quickly by the pressure because the oil pressure in the hydraulic chamber 33 acts on the oil chamber 42a through the discharge hole 37a together with the pressure reduction of the pressure receiving chamber 41b, and the free piston 42 moves to the dashed line in FIG. As shown, the discharge hole 37a communicates with the discharge path 37b. Therefore, first, the hydraulic pressure in the hydraulic chamber 33 is discharged from the discharge passage 37 into the oil pan.

Subsequently, when the free piston 42 moves further downward, the tapered outer peripheral surface of the upper end portion 42a opens the open end 50c of the bypass passage 50, and the free piston 42 moves downward by the pressure acting on the upper end portion 42a. It moves promptly, and the bypass passage 50 is fully opened. As a result, the hydraulic pressure (hydraulic oil) in the hydraulic chamber 33 is
The fluid flows into the oil chamber 41a from 0 and merges with the hydraulic oil from the discharge hole 37a, and is discharged to the outside from each of the discharge paths 37a and the downstream portion 50b, so that the pressure inside the hydraulic chamber 33 quickly becomes low. For this reason, the piston 32 moves to the lowest position as shown in FIG. 1 and closes the exhaust valve 21 to release the operation of the engine brake, thereby permitting the drive cam 23 to perform a normal opening / closing operation.

As described above, according to this embodiment, when the operation of the engine brake is released, the discharge passage 37 and the bypass passage 50 are opened almost simultaneously with the discharge passage 37, so that the entire passage cross-sectional area becomes large, and the hydraulic chamber 33 is opened. The hydraulic pressure in the hydraulic chamber 33 is discharged from the two passages 37 and 50 almost at the same time.
2, the descending speed becomes faster. As a result, the response to release of the engine brake operation is improved, and the closing operation of the exhaust valve 22 is quickened, thereby improving the exhaust emission performance, that is, preventing generation of white smoke of the exhaust gas and instability of the engine rotation. it can.

In addition, since the pressure in the hydraulic chamber 33 can be quickly reduced when the engine brake operation is released, simply by providing the bypass passage 50 in addition to the discharge passage 37, the device is prevented from becoming complicated and large. As well as
An increase in manufacturing cost can also be suppressed.

The bypass passage 50 is merely opened and closed without greatly affecting the sliding of the free piston 42, so that the passage cross-sectional area can be set large. As a result, the performance of discharging the hydraulic pressure from the hydraulic chamber 33 is improved, and the responsiveness of the operation release of the engine brake is further improved.

FIG. 3 shows a second embodiment of the present invention, in which the position of the downstream portion 50b of the bypass passage 50 is located slightly below, and the free piston 42 descends to the upper outer peripheral surface of the free piston 42 at the maximum. When the bypass passage 5
An annular groove groove 51 is formed in which the opening end 50c of the zero coincides.

Therefore, according to this embodiment, the oil pressure in the hydraulic chamber 33 can be discharged from both the discharge passage 37 and the bypass passage 50, so that the pressure can be promptly reduced. Since the flow passages of the passages 50 can be formed separately, the upper part of the piston hole 41 is divided into the two passages 37, 5 as in the previous embodiment.
Since the entire passage cross-sectional area can be set larger than in the case where the common passage is 0, the hydraulic discharge speed can be further increased. As a result, the engine brake operation release responsiveness can be further improved.

FIG. 4 shows an embodiment corresponding to claim 5, wherein the basic structure is the same as that of each of the above-mentioned embodiments, except that the bypass passage is eliminated and the piston hole 4 is omitted.
A return spring 52, which is a spring member that urges the free piston 42 downward, that is, urges the discharge hole 37a in the opening direction, is provided in the upper oil chamber 41a.

That is, the return spring 52
Is formed in a substantially conical shape, and the upper end 52a has an oil chamber 41a.
The lower end 52b is elastically disposed on the tapered surface of the upper end 42a of the free piston 42 while being elastically contacting the lower surface of the upper wall. The return spring 52 is easily compressed and deformed by the hydraulic pressure introduced from the supply passage 36 into the pressure receiving chamber 41b, closes the discharge hole 37a by the rise of the free piston 42, and releases the free piston 42 when the hydraulic pressure of the pressure receiving chamber 41b is released. Is set to such a degree as to lower the pressure.

Therefore, according to this embodiment, when the supply of the hydraulic pressure to the hydraulic chamber 33 is interrupted when the operation of the engine brake is released, the hydraulic pressure supplied from the hydraulic chamber 33 into the oil chamber 41a is reduced. And the combined force of this differential pressure and the spring force of the return spring 52 acts on the upper end 42 a of the free piston 42. For this reason, the free piston has a lower descending speed, so that the discharge hole 37a and the discharge path 37b are quickly communicated. As a result, the downward movement speed of the piston 32 is increased, and the responsiveness of releasing the operation of the engine brake is improved. As a result, such as improved exhaust emission performance,
The same excellent operational effects as those of the above embodiments can be obtained.

The present invention is not limited to the configuration of each of the above embodiments. For example, the structure of the free piston 42 can be changed as appropriate according to the application. Also,
In the second embodiment, only the discharge passage 37 is provided.
If this is combined with a bypass passage, the hydraulic pressure in the hydraulic chamber 33 can be discharged at a higher speed.

[0052]

As is apparent from the above description, claim 1
According to the inventions described in (1) to (3), when the operation of the engine brake is released, the discharge passage and the bypass passage are opened, and the hydraulic pressure in the hydraulic chamber is discharged to the outside from both the passages. As a result, the lowering speed of the piston increases. As a result, the response to release of the engine brake is improved, and the closing operation of the exhaust valve is quickened, so that the exhaust emission performance can be improved, that is, generation of white smoke of the exhaust gas and instability of the engine rotation can be prevented. .

Further, since the pressure in the hydraulic chamber can be quickly reduced when the engine brake operation is released, simply by providing a bypass passage in addition to the discharge passage, the device is prevented from becoming complicated and large. In addition, an increase in manufacturing cost can be suppressed.

According to the fourth aspect of the present invention, since the discharge passage and the bypass passage can be formed separately by forming the groove, the entire cross-sectional area of each passage can be set large. Will be possible. Therefore, the efficiency of discharging the hydraulic pressure from the hydraulic chamber is further improved, and the responsiveness of releasing the operation of the engine brake is further improved.

According to the fifth aspect of the invention, the free piston is moved downward when the operation of the engine brake is released by the combined force of the differential pressure at both ends of the piston hole and the return spring. The descending movement speed is increased, and the discharge passage is opened by the free piston, thereby increasing the speed. As a result, the descending movement speed of the piston is also increased, and the response to canceling the engine brake operation is improved.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing the actuator of the embodiment.

FIG. 3 is an essential part cross-sectional view showing an actuator according to a second embodiment of the present invention.

FIG. 4 is an essential part cross-sectional view of an actuator showing an embodiment corresponding to claim 5;

FIG. 5 is a longitudinal sectional view showing an engine brake device to which a conventional actuator is applied.

FIG. 6 is a sectional view showing the conventional actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Exhaust valve 22 ... Driving means 23 ... Variable means 24 ... Rocker shaft 25 ... Rocker arm 26 ... Eccentric bush 27 ... Lever part 28 ... Actuator 29 ... Valve mechanism 30 ... Body 31 ... Cylinder 32 ... Piston 33 ... Hydraulic chamber 34 ... Hydraulic pressure Circuit 36 Supply passage 37 Discharge passage 42 Free piston 50 Bypass passage 51 Groove groove 52 Return spring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Shibukawa 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. (72) Inventor Seiji Tsuruta 1370 Onna, Atsugi-shi, Kanagawa Prefecture F-term in Unisia Gex Co., Ltd. FA15 FA34 HE01Z

Claims (5)

[Claims] A piston connected to an exhaust valve of an engine, a cylinder accommodating the piston in a slidable manner, and supplying and discharging hydraulic pressure to a hydraulic chamber in the cylinder via a supply passage and a discharge passage. A hydraulic circuit that slides the piston and a free piston slidably provided in the piston hole, the discharge passage is provided in accordance with a differential pressure between the hydraulic pressure in the hydraulic chamber and the hydraulic pressure flowing through the supply passage. An actuator for an engine brake device, comprising: a valve mechanism for controlling the opening and closing of the engine, wherein a bypass passage that bypasses the discharge passage and discharges the hydraulic pressure in the hydraulic chamber to the outside is provided. 2. The method according to claim 2, wherein the bypass passage is formed so as to substantially cross the piston hole from the hydraulic chamber in the radial direction, and the opening end of the bypass passage is controlled to open and close according to the sliding position of the free piston. The actuator for an engine brake device according to claim 1, wherein: 3. A discharge hole penetrating the upper wall of the piston hole to communicate the hydraulic chamber with the piston hole, and a discharge hole penetrating the upper end of the side wall of the piston hole to communicate with the piston hole. The bypass passage is formed in a substantially bent shape in the side wall of the piston hole, has an upstream portion opened at a substantially central position of the hydraulic chamber, and has a downstream portion formed with a piston. The actuator for an engine brake device according to claim 2, wherein the hole is formed so as to penetrate the hole from a diametric direction. 4. The free piston according to claim 1, wherein a groove is formed on an outer periphery of the free piston so as to coincide with an opening end of the bypass passage at a predetermined downward movement position of the free piston. The actuator of the engine brake device according to claim 1. 5. A piston connected to an exhaust valve of an engine, a cylinder accommodating the piston slidably therein, and supplying and discharging hydraulic pressure to a hydraulic chamber in the cylinder via a supply passage and a discharge passage. A hydraulic circuit that slides the piston and a free piston slidably provided in the piston hole, the discharge passage is provided in accordance with a differential pressure between the hydraulic pressure in the hydraulic chamber and the hydraulic pressure flowing through the supply passage. An engine brake device having a valve mechanism for controlling the opening and closing of the engine, wherein a spring member for urging the free piston in a direction to close the discharge hole is provided below the piston hole. Actuator of brake device.