JP2001263017A - Actuator for engine brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness of an operation of an engine brake and hold stability by suppressing instability of a behavior at the time of the maximum raising as well as restricting descent return phenomenon of a piston when the piston is risen. SOLUTION: This device is provided with a cylinder 31 in which a piston 32 coupled with an exhaust valve 21 is housed inside, a hydraulic circuit 34 for sliding the piston by supplying/delivering oil pressure to/from the inside of a hydraulic chamber 33 of the cylinder through a supplying passage 36 and a delivery passage 37, and a valve mechanism 29 for openingly/closingly controlling the delivery passage. In this valve mechanism, an opening end 37c of the delivery passage is openingly/closingly controlled sliding a free piston slidably disposed in the piston hole 41 by relative pressure between oil pressure in a pressure receiving chamber 41b and pilot oil pressure from an orifice 47 for communicating the hydraulic chamber and the piston hole with each other.

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, one described in, for example, Japanese Patent Application Laid-Open Publication No. HEI 9-213 is known.

Referring to FIGS. 12 and 13, a rocker arm 1 for opening and closing an exhaust valve 2 is supported by a rocker shaft 4 with an eccentric bush 3 interposed therebetween.

The eccentric bush 3 is provided with a hydraulic actuator 5 disposed in a rocker cover of a cylinder head 6.
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. 13, the hydraulic actuator 5 has a hydraulic chamber A separated below a piston 6 slidably housed in a cylinder 9. 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 valve mechanism 14 for releasing the hydraulic pressure in the hydraulic chamber A to the low pressure side.

The valve mechanism 14 includes a piston hole 15 formed in parallel with the hydraulic pressure introduction path 13,
A discharge hole 16 communicating with the upper end of the oil pressure chamber A, a discharge passage 17 formed on the side of the piston hole 15, and a communication passage 18 communicating the lower end of the piston hole 15 with the hydraulic supply passage 7. A free piston 19 is provided in the piston hole 15 so as to be slidable up and down, and communicates or shuts off the discharge passage 17 and the discharge hole 16.

When the pressure difference between the hydraulic pressure chamber A and the hydraulic pressure supply passage 7 becomes larger than a predetermined value, the free piston 19 moves to the communication passage 18 so that the discharge passage 17 is moved through the discharge hole. The hydraulic chamber A is configured to be opened by communicating with the hydraulic chamber A via the control valve 16.

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, since the pressure acting on the upper surface of the free piston 19 of the valve mechanism 14 is larger than the pressure acting on the lower surface, the discharge hole 16 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 solenoid valve 9 is closed and the supply of the hydraulic pressure from the oil pump 8 is stopped, the pressure on the hydraulic supply passage 7 decreases, and the piston 6 on which the reaction force of the valve system acts. Is compressed and the pressure on the hydraulic chamber A side rises relatively, so that the free piston 19 descends toward the communication passage 18 and the discharge passage 17 is opened. As a result, the hydraulic pressure in the hydraulic chamber A flows from the discharge hole 16 to the discharge passage 1717 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.

[0011]

By the way, in this engine brake device, when the engine brake is operated, the exhaust valve 2 is naturally brought into the lift state (open state) even during the compression stroke of the engine. Therefore, a large compression load during the compression stroke acts on the eccentric bush 3 via the exhaust valve 2 and the rocker arm 1, and further acts on the piston 6 from the piston rod 6 a of the hydraulic actuator 5, and the inside of the hydraulic chamber A is changed. Where the high pressure state
In the conventional engine brake device, since the passage cross-sectional area of the discharge hole 16 in the valve mechanism 14 is relatively large, high hydraulic pressure in the hydraulic chamber A flows into the piston hole 15 from the discharge hole 16. As a result, the free piston 19 is pressed and moved downward. As a result, the hydraulic pressure in the hydraulic chamber A is discharged from the discharge passage 17 to the outside, and the piston 6 instantaneously descends and the behavior becomes unstable.
As a result, it becomes difficult to maintain the lift state of the exhaust valve 2 stably, and the operation responsiveness from the start of operation of the engine brake to the peak is deteriorated.

That is, when the operation of the engine brake is started and the hydraulic pressure is supplied from the hydraulic pressure supply passage 7 into the hydraulic chamber A via the check valve 11 and the piston 6 tries to rise, it acts on the piston 6 during the compression stroke. Since the supply oil pressure in the hydraulic chamber A is discharged from the discharge hole 16 due to the large downward pressure, the piston 6 gradually rises while temporarily returning once within the range of the arrow in the drawing as shown in FIG. It will go. Therefore, the lift operation responsiveness of the exhaust valve 2 is reduced, and the engine brake cannot be quickly operated.

Therefore, it is conceivable to restrict the flow of the hydraulic pressure from the hydraulic chamber A to the discharge hole 16 by making the passage cross-sectional area of the discharge hole 16 sufficiently small. In this case, the operation of discharging the hydraulic pressure from the hydraulic chamber A when the engine brake is released is deteriorated, and the operation responsiveness of the release is reduced.

Although it is possible to increase the volume of the hydraulic chamber A without changing the size of the discharge hole 16, it is possible to increase the volume of the hydraulic chamber A. This leads to another technical problem that the weight is increased and the degree of freedom of layout is restricted.

[0015]

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 of the cylinder through a supply passage and a discharge passage, and a valve mechanism that controls opening and closing of the discharge passage In the actuator of the engine brake device comprising:
The opening and closing of the discharge passage is controlled by a pilot pressure taken out of the hydraulic chamber through an orifice.

Therefore, according to the present invention, when the hydraulic pressure in the hydraulic chamber is increased by operating the engine brake, the high hydraulic pressure in the hydraulic chamber directly acts on the free piston from a relatively large discharge hole as in the prior art. Instead, it acts as the pilot pressure taken out through the orifice, so that the free sliding of the free piston is prevented, and the behavior of the actuator can be prevented from becoming unstable.

According to a second aspect of the present invention, the valve mechanism comprises:
The orifice, a piston hole communicating with the hydraulic chamber via the orifice, and a free piston slidably provided in the piston hole, while the discharge passage is formed from the hydraulic chamber to the piston. The hole is formed so as to cross substantially from the radial direction, and the supply passage is communicated with the piston hole on the opposite side of the orifice forming position with the free piston interposed therebetween.

According to a third aspect of the present invention, the orifice-side tip portion of the free piston is formed to be tapered, and the discharge passage is formed so as to cross a substantially central position in the axial direction of the piston hole. After the free piston strokes to a predetermined position by the pilot pressure and the discharge passage is slightly opened by the distal end, the free piston is further stroke-moved in the same direction according to the magnitude of the oil pressure in the discharge passage. The opening area of the discharge passage is controlled to be enlarged.

According to a fourth aspect of the present invention, there is provided a piston linked to an exhaust valve of an engine, a cylinder accommodating the piston slidably therein, and a supply passage and a discharge passage in a hydraulic chamber of the cylinder. In an actuator of an engine brake device including a hydraulic circuit that slides the piston by supplying and discharging hydraulic pressure, and a valve mechanism that controls opening and closing of the discharge passage, the valve mechanism is provided near the hydraulic chamber. A piston hole, a check hole communicating between the hydraulic chamber and the piston hole, a free piston slidably provided in the piston hole, and a free piston slidably provided in the check hole. And a check pin that opens and closes the check hole in accordance with the pressure of the hydraulic piston and presses and moves the free piston. To form a et said piston bore so as to cross approximately the radial direction, characterized in that the free piston sandwiching the check hole opposite side of the piston bore and communicates with the supply passage.

According to a fifth aspect of the present invention, there is provided a piston linked to an exhaust valve of an engine, a cylinder accommodating the piston slidably therein, and a hydraulic pressure chamber in a hydraulic chamber of the cylinder via a supply passage and a discharge passage. A hydraulic circuit that slides the piston by supplying and discharging the fluid, and a valve mechanism that controls the opening and closing of the discharge passage by a free piston slidably provided in the piston hole. The tip of the free piston at the one end of the piston hole is formed to have a small diameter, and the free piston is introduced to the one end of the piston hole via a communication hole formed between the hydraulic chamber and the piston hole. The piston is slid by the relative pressure between the hydraulic pressure and the hydraulic pressure introduced from the supply passage side to the other end side of the piston hole, and the outer diameter of the piston is D1, When the outer diameter of the front end portion of the piston is D2, the outer diameter of the rear end portion of the free piston is D3, the input load of the piston in the compression direction is F, and the hydraulic pressure from the supply passage is P, the respective outer diameters D1, D2, D3,

[0021]

(Equation 2)

It is characterized in that it is set as follows.

[0023]

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 opening of an exhaust port. The valve seat provided at the end is detached and seated to open and close the open end.

The driving means 22 includes a rocker shaft 24 extending along the longitudinal direction 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. , 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.

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 allowing hydraulic pressure to flow 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 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 in a substantially L-shape in the lower wall of the body 30. An upper end 37a is formed at the center of the bottom surface of the hydraulic chamber 33, while a lower end 37b is formed. An opening is formed in the outer surface of the body 30 and communicates therefrom with an oil pan (not shown). The passage cross-sectional area of the discharge passage 37 is formed relatively large,
It is formed larger than the conventional discharge hole 16.

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 so as to vertically penetrate an axial center of a downstream portion of the discharge passage 37 extending in the horizontal direction, and has a small diameter whose upper portion is formed to penetrate the lower wall in the vertical direction. The orifice 47 communicates with the hydraulic chamber 33, and the lower pressure receiving chamber 41b communicates with the horizontal passage 36b.

The free piston 42 has an upper end 42a.
Is formed in the shape of a truncated cone, and the oil pressure of the hydraulic chamber 33 acts as pilot pressure through the orifice 47 on the flat upper surface and the tapered upper peripheral surface of the upper end portion 42a. The outer peripheral surface of the lower cylindrical portion 42b controls opening and closing of an open end 37c of the discharge passage 37 facing the piston hole 41. The free piston 42 opens and closes the opening end 37c of the discharge passage 37 in the vertical direction by a relative pressure between a signal oil pressure supplied and discharged from the supply passage 36 into the pressure receiving chamber 41b and a pilot pressure from the orifice 47. And a plug 43 for closing the lower opening of the piston hole 41.
The open end 37c is maximally opened by the outer peripheral surface of the upper end portion 42a at the maximum descending position where the upper end 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 accelerator pedal is released during normal operation of the vehicle and the driver operates the engine brake, a switching signal is output from the controller 44 to the solenoid valve 39 and supplied from the drain passage 45. The passage is switched to the passage 36. Therefore, the oil pump 38
Is supplied into the hydraulic chamber 33 while pushing and opening the check ball 40a through the supply passage 36. At the same time, signal hydraulic pressure is supplied from the horizontal passage portion 36b to the pressure receiving chamber 41b of the piston hole 41, and the free piston 42
Of the orifice 47 is closed by 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.

When the piston 32 moves upward and is held at the maximum raised position, the piston 32 is moved from the exhaust valve 21 to the piston 32 via the eccentric bush 26 and the rocker arm 25 during the compression stroke of the engine. A large load acts downward, and a high pressure is generated in the hydraulic chamber 33. Therefore, a large pressure is applied to the discharge passage 37 in the discharge direction, but only the hydraulic pressure acts on the upper end 42a of the free piston 42 through the small-diameter orifice 47. At this time, the pressure from the orifice 47 Since the hydraulic pressure in the pressure receiving chamber 41b is sufficiently larger than the pressure, the free piston 42 is held at the raised position. Therefore, the discharge passage 3 is formed by the outer peripheral surface of the free piston 42.
7 is maintained in a closed state, and the discharge passage 3 is closed.
The discharge of hydraulic pressure from the outside to the outside is reliably restricted.

As a result, the free sliding of the piston 32 in the vertical direction is suppressed, and the occurrence of the return phenomenon (down phenomenon) during the upward movement as in the prior art is sufficiently suppressed. For this reason, the ascending movement speed of the piston 32 is improved, and the operation response of the engine brake is improved. Further, since the downward movement is suppressed at the maximum rising position of the piston 32, the piston 32 can be stably maintained at the maximum rising position.

Next, when 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. State. For this reason,
The free piston 42 lowers the pressure in the pressure receiving chamber 41 b and the hydraulic pressure in the hydraulic chamber 33 is increased through the orifice 47.
2a, the pressure lowers quickly due to this pressure, and as shown by the dashed line in FIG.
The opening end 37c of the discharge passage 37 is opened at the tapered outer peripheral surface of the above. As a result, the hydraulic pressure in the hydraulic chamber 33 is quickly discharged from the discharge passage 37, and the internal pressure is reduced. 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, in the present embodiment, a small-diameter orifice 47 for generating a pilot pressure is used instead of having a relatively large-diameter discharge hole directly facing the upper end portion 42a of the free piston 42 as in the related art. As a result, even if a high pressure due to the compression input load applied to the piston 32 acts on the hydraulic chamber 33, the free downward movement of the free piston 42 can be sufficiently suppressed, thereby improving the operation responsiveness of the engine brake and improving the operation. Stabilization can be achieved.

In addition, since the above-described free downward movement of the piston 32 can be restricted without increasing the cross-sectional area of the cylinder 31, the size and weight of the apparatus can be suppressed.

Further, the discharge passage 37 is merely opened and closed without the hydraulic pressure flowing therethrough directly contributing to the opening and closing operation of the free piston 42. Therefore, the passage cross-sectional area may be set large. it can. As a result, the performance of discharging the hydraulic pressure from the hydraulic chamber 33 is improved, and the responsiveness of releasing the operation of the engine brake is also improved.

The shape of the upper end 42a of the free piston 42 can be changed arbitrarily.
For example, as shown in FIG. 3, the upper end portion 42 a is formed in a hemispherical shape, or as shown in FIG. 4, is formed in a substantially triangular pyramid shape, and the leading edge 42 c is engaged with the lower end opening of the orifice 47. It is also possible to close it.

FIGS. 5 and 6 show an embodiment corresponding to claim 4 of the present invention. The basic structure of the piston hole 41, the discharge passage 37, the free piston 42, etc. is the same as that of the above-described embodiment. The orifice 4 is particularly different.
7 is provided with a check hole 60 communicating the hydraulic chamber 33 and the piston hole 41 and a check pin 61 sliding in the check hole 60.

More specifically, the check hole 60
Is formed in the upper wall of the piston hole 41 in the vertical direction, is formed in a substantially T-shaped vertical cross section, and has a large-diameter upper portion 60.
a faces the hydraulic chamber 33, and a small diameter lower portion 60 b faces the piston hole 41.

On the other hand, the check pin 61 is formed in a substantially T-shape having the same shape as the check hole 60, and has an outer peripheral surface of an upper large-diameter flange portion 61a and a lower small-diameter shaft portion 61b. A minute gap is formed between each inner peripheral surface of the upper part 60a and the inner peripheral surface of the lower part 60b, and the inside of the check hole 60 is slidable up and down. Also,
The maximum lowering position of the check pin 61 is regulated at a position where the lower surface of the flange portion 61a is in contact with the step surface 62 between the upper and lower portions 60a and 60b, and the distal end of the shaft portion 61b is moved to the maximum lowering position. Presses the top of the triangular pyramid upper end 42a of the free piston 42. Further, the length of the shaft portion 61b is
2 is pressed to the maximum descending position as described above, the peripheral edge 42c between the upper end 42a and the lower end 42b of the free piston 42 is slightly smaller than the upper edge of the open end 37c of the discharge passage 37. It is set to be in the lowered position.

Therefore, according to this embodiment, when the driver depresses the brake pedal and activates the engine brake, the hydraulic pressure pumped from the oil pump 38 is supplied from the supply passage 36 through the solenoid valve 39 as described above. It is supplied into the hydraulic chamber 33 through the check valve 40, whereby the piston 32 moves upward. At this time, when the input load at the time of the compression stroke acts on the hydraulic chamber 33 and becomes high pressure,
A pressure greater than the supply oil pressure applied to the lower surface of the free piston 42 acts on the upper surface of the flange portion 61a, and the check pin 61 slides down in the check hole 60. Therefore, the free piston 42 is connected to the shaft 6 of the check pin 61.
At this time, since the discharge passage 37 is still held in the fully closed state by the free piston 42, the discharge operation from the discharge passage 37 is not performed, and the check pin 61 is slightly moved. Only leaks from the minute gap between the hole and the check hole 60. Therefore, the return phenomenon of the piston 32 is sufficiently prevented, and the piston 3
2 can be quickly moved upward.

When the check pin 61 hits the step surface 62 and descends to the maximum descending position, the outer peripheral edge 42c of the free piston 42 is moved to the open end 37c of the discharge passage 37.
By moving to a position below the upper edge, the discharge passage 37 is slightly opened. However, since the opening area is extremely small, the discharge amount from the discharge passage 37 is very small. Accordingly, the piston 32 slightly descends due to a small fluctuation in the hydraulic pressure in the hydraulic chamber 33, but does not generate a large return phenomenon as in the conventional example, but rises at a high speed, so that a good operation response of the engine brake is achieved. Performance can be ensured, and a stable holding state can be obtained at the maximum rising position of the piston 32.

When the operation of the engine brake is released, the supply of the hydraulic pressure from the supply passage 36 to the pressure receiving chamber 41b is stopped, and the internal pressure of the pressure receiving chamber 41b decreases. Moves quickly from the state where the free piston 42 is pressed at the maximum lowering position to the maximum lowering position by the hydraulic pressure in the discharge passage 37. For this reason, the passage cross-sectional area of the discharge passage 37 is maximized, the hydraulic pressure in the hydraulic chamber 33 is quickly discharged to the outside, and the piston 32 can be quickly moved downward. As a result, the engine brake release operation responsiveness is also improved.

The shapes of the check hole 60 and the check pin 61 can be variously changed. For example, as shown in FIG. 7, the check hole 60 is formed in a substantially columnar shape, and the lower end edge is reduced in diameter. On the other hand, the head 61a of the check pin 61 may be formed in a ball shape. Also,
As shown in FIG. 8, the step surface 62 of the check hole 60 is formed in a conical taper shape, while the head 61a of the check pin 61 is formed.
May be formed in a trumpet shape corresponding to the stepped surface 62.

FIGS. 9 and 10 show an embodiment corresponding to claim 5 of the present invention. The constructions of the piston hole 41 and the discharge passage 37 are the same as those of the above-described embodiment. The orifice 41 is not an orifice, but is formed by a communication hole 70 having a relatively larger cross-sectional area than the orifice. Further, the free piston 42 has an upper end portion 42a, which is a tip end portion, formed in a truncated cone shape. The outer diameter D1 of the piston 32 and the free piston 4
The outer diameter D2 of the upper end 42a and the outer diameter D3 of the lower end 42b of the free piston 42 are set as follows.

That is, when the engine brake is actuated, the input load in the compression direction acting on the piston 32 during the compression stroke as described above is applied to the F, the supply passage 36 to the hydraulic chamber 33 and the pressure receiving chamber 41b of the piston hole 41. If the acting hydraulic pressure is P,

[0057]

(Equation 3)

The inner and outer diameters D1 to D3 are set such that

The reason for setting the inner and outer diameters D1 to D3 is to hold the free piston 42 at the raised position by the following equation. That is, P1 × π / 4 × D
² = force to drop the free piston 42... 1 P × π / 4 × D3 ² = force to lift the free piston 42. Reference numeral 42 holds the raised position without falling.

Therefore, according to this embodiment, by setting the input load F acting on the piston 32 in the compression direction as a high input in the transient state, it is possible to effectively prevent the return phenomenon during the upward movement of the piston 32. Can be prevented.

As another example, the outer diameters D1, D2, D
3 is set in the same manner as described above, and the configuration of the free piston 42 and the like is formed as shown in FIG.
It is also possible to control the opening area of the opening end 37c of the discharge passage 37 by a and 71b.

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.

[0063]

As is apparent from the above description, claim 1
According to the actuators of the engine brake devices according to the inventions described in any of the first to fifth aspects, even if a large input load in the compression direction acts on the piston during the compression stroke of the engine, the hydraulic pressure in the hydraulic chamber is discharged to the outside from the discharge passage. Can be regulated,
The return phenomenon during the upward movement of the piston can be effectively prevented. As a result, the responsiveness of the operation of the engine brake by the actuator is improved, and the behavior of the piston at the time of maximum rise can be prevented from becoming unstable, so that the stable operation of the engine brake can be obtained.

Further, since the discharge passage is not formed at a position which affects the sliding action of the free piston, but is formed at a position which is simply opened and closed by the free piston, the passage cross-sectional area of the discharge passage is set as large as possible. It becomes possible to do. As a result, the operation of discharging the hydraulic pressure in the hydraulic chamber when the engine brake is released can be quickly performed, and the response to release of the engine brake can be improved.

In addition, the present invention merely changes the configuration of the discharge passage and the orifice, so that the above-mentioned excellent effects can be obtained without causing problems such as an increase in the size and weight of the apparatus.

[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 a longitudinal sectional view of an actuator showing another example of a free piston.

FIG. 4 is a longitudinal sectional view of an actuator showing still another example of a free piston.

FIG. 5 is a longitudinal sectional view of an actuator showing an embodiment corresponding to claim 4;

FIG. 6 is an enlarged sectional view of the same embodiment.

FIG. 7 is an essential part cross-sectional view of the actuator showing another example of the check holes and the check pins provided in the embodiment.

FIG. 8 is an essential part cross-sectional view of an actuator showing another example of the check hole and the check pin.

FIG. 9 is a longitudinal sectional view showing an embodiment of an actuator corresponding to the invention described in claim 5;

FIG. 10 is an enlarged sectional view of a main part of the embodiment.

FIG. 11 is an essential part cross-sectional view of an actuator showing another example of the free piston provided in the invention.

FIG. 12 is a longitudinal sectional view showing an engine brake device to which a conventional actuator is applied.

FIG. 13 is a sectional view showing the conventional actuator.

FIG. 14 is a graph showing an operation of a piston by 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 40, 62 Check valve 42 Free piston 47 Orifice

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Shibukawa 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. F term (reference) 3G018 AB06 AB19 BA38 CA19 DA31 DA53 DA57 FA20 GA04 GA12 GA33 GA38 3G092 AC01 DA02 DA06 DA15 DF04 DF09 DF10 DG05 DG09 EA11 EA13 EA15 EA28 EA29 FA06 FA34 FA50 GB08 HE01Z HE03Z

Claims (5)

[Claims] 1. 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 of the cylinder via a supply passage and a discharge passage. An actuator of an engine brake device including a hydraulic circuit that slides the piston and a valve mechanism that controls opening and closing of the discharge passage, wherein the valve mechanism is configured to operate by a pilot pressure taken out of the hydraulic chamber through an orifice. An actuator for an engine brake device, which controls opening and closing of a discharge passage. 2. The valve mechanism, comprising: the orifice; a piston hole communicating with the hydraulic chamber via the orifice;
A free piston slidably provided in the piston hole, the discharge passage is formed so as to substantially cross the piston hole from the hydraulic chamber in the radial direction, and sandwiches the free piston. 2. The actuator according to claim 1, wherein the supply passage communicates with a piston hole opposite to a position where the orifice is formed. 3. The orifice-side tip of the free piston is tapered, and the discharge passage is formed so as to traverse an axially central position of the piston hole. After the stroke is moved to a predetermined position by the pressure and the discharge passage is slightly opened by the distal end, the free piston is further stroke-moved in the same direction according to the magnitude of the oil pressure in the discharge passage to reduce the opening area of the discharge passage. The actuator of the engine brake device according to claim 2, wherein the enlargement control is performed. 4. A piston linked to an exhaust valve of an engine, a cylinder accommodating the piston slidably therein, and supplying and discharging hydraulic pressure to a hydraulic chamber of the cylinder via a supply passage and a discharge passage. In an actuator of an engine brake device including a hydraulic circuit that slides the piston and a valve mechanism that controls opening and closing of the discharge passage,
The valve mechanism includes a piston hole provided in the vicinity of the hydraulic chamber, a check hole communicating the hydraulic chamber with the piston hole, a free piston slidably provided in the piston hole, A check pin, which is slidably provided in the hole, opens and closes the check hole according to the pressure in the hydraulic chamber and presses and moves the free piston, while the discharge passage extends from the hydraulic chamber to the piston. An actuator for an engine brake device, characterized in that the hole is formed so as to cross substantially from the radial direction, and the inside of the piston hole opposite to the check hole across the free piston communicates with the supply passage. 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 of the cylinder via a supply passage and a discharge passage. An actuator for an engine brake device comprising: a hydraulic circuit for sliding the piston; and a valve mechanism for opening and closing the discharge passage by a free piston slidably provided in the piston hole. An oil pressure introduced into one end of the piston hole through a communication hole formed between the hydraulic chamber and the piston hole, the oil pressure being supplied to the supply passage; The piston is slid at a relative pressure with the hydraulic pressure introduced into the other end of the piston hole from the side, and the outer diameter of the piston is D1, and the outer diameter of the tip of the free piston is D1. 2. When the outer diameter of the rear end of the free piston is D3, the input load of the piston in the compression direction is F, and the oil pressure from the supply passage is P, the respective outer diameters D
1, D2 and D3 are given by An actuator for an engine brake device, wherein the actuator is set as follows.