JPH09264114A - Compression pressure release-type brake device in engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a connecting structure between an eccentric bush and an actuator by preventing the associative rotation of the eccentric bush during the swinging of a locker arm following the opening/closing of a valve in a compression pressure release-type brake device. SOLUTION: By providing a preset spring 7 for adding a specified preset load in an operation direction corresponding to the valve closing direction of an arm section 2A in the arm section 2A of an eccentric bush 2, the associative rotation of the eccentric bush 2 caused by a friction force between a locker arm swung along the peripheral surface of the eccentric bush 2 and the eccentric bush 2 is prevented during the opening/closing of an exhaust valve. In particular, during the OFF time of a compression pressure open-type brake device, by softening an impact force caused by the repetition of the cycle of an associative rotation and the seating of the exhaust valve, the durability of a connecting structure between the eccentric bush 2 and a hydraulic cylinder device is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression pressure release type brake device which obtains a braking force by opening an exhaust valve to release the compression pressure for the purpose of assisting an engine braking force and the like, and particularly to an operating mechanism thereof. Related to improved technology.

[0002]

2. Description of the Related Art Conventionally, as a compression pressure release type brake device (decompression brake device) of this type, one disclosed in Japanese Patent Laid-Open No. 6-193416 has been known. For example, FIGS. It is configured as shown.
That is, an eccentric bush 2 which is integrally rotatably fixed to a rocker shaft 1 which is rotatably supported and has a rotation center Y which is eccentric from a rotation center X of the rocker shaft 1.
The rocker arm 3 for operating the exhaust valve is rotatably supported on the outer peripheral surface of the eccentric bush 2 and swings about the rotation center Y of the eccentric bush 2.

Further, the eccentric bush 2 is provided with an arm portion 2A extending from an outer peripheral portion of the eccentric bush 2, and an actuator which is connected to a tip end portion of the arm portion 2A and swings the arm portion 2A. Is provided as a hydraulic cylinder device 4. Then, by swinging the arm portion 2A by the hydraulic cylinder device 4,
The eccentric bush 2 is rotated so that its rotation center Y position moves and changes with respect to the rotation center X of the rocker shaft 1.
The exhaust valve of the engine is opened via the rocker arm 3.

[0004]

In the rotating mechanism of the eccentric bush in such a conventional device, the rocker arm 3 is turned on when the exhaust opening type brake device is activated (ON).
), It swings when the exhaust valve opens and closes, regardless of whether it is inactive (OFF). As a result of the rocker arm 3 swinging along the peripheral surface of the eccentric bush 2, as a result of the frictional force between the rocker arm 3 and the eccentric bush 2, the eccentric bush 2 is rotated, so that a proper valve lift is obtained. Cause trouble.

Therefore, the arm portion 2A of the eccentric bush 2 is
The linking structure between the hydraulic cylinder device 4 and the hydraulic cylinder device 4 as an actuator is important. For example, as a conventional linking structure between the arm portion 2A of the eccentric bush 2 and the hydraulic cylinder device 4,
The pin 6 fixed so as to traverse the groove 5 provided at the tip portion of the actuating rod 4A of the hydraulic cylinder device 4 and the groove 2a formed at the tip portion of the arm portion 2A are engaged with each other to form the arm portion 2A. There is a system in which the hydraulic cylinder device 4 and the hydraulic cylinder device 4 are linked.

In such a structure, when the compression pressure release type brake device is turned on, the piston 4 of the hydraulic cylinder device 4 is turned on.
The upward movement of B raises the operating rod 4A, and the eccentric bush 2 rotates in the direction of arrow A in FIG. At this time, the force to rotate the eccentric bush 2 is caused by the arrow B in FIG.
Direction is applied, the piston 4B is pressed upward by the application of the hydraulic pressure, and the piston 4B moves in the cylinder body 4
Since the end wall 4a comes into contact with the inner surface of the end wall 4a of C, that is, the end wall 4a serves as a stopper, the eccentric bush 2 having the arm portion 2A pin-connected to the piston 4B is prevented from rotating together, so that there is no problem.

However, the OF of the compression pressure release type brake device
At the time of F, as shown in FIG. 8, the operating rod 4A descends due to the downward movement of the piston 4B of the hydraulic cylinder device 4, and the eccentric bush 2 rotates in the direction of arrow C in the figure. At this time, when the force to rotate the piston 4 is applied to the eccentric bush 2 in the direction of arrow D in FIG.
Since there is no stopper to prevent the upward movement of B, the eccentric bush 2 is rotated with the arm portion 2A,
This is particularly noticeable in the high engine speed range.

When an urging force such as a valve spring is applied to the rocker arm 3, a force for returning the eccentric bush 2 by the amount of the eccentricity is generated. This force is the hydraulic cylinder device in the direction of arrow E in FIG. It becomes the force to push 4. And
When this force is applied when the entrainment described above occurs, the exhaust valve tries to seat rapidly, and the impact force generated at that time causes the structure of linkage between the eccentric bush 2 and the hydraulic cylinder device 4 (arm). Part 2A, cylinder body 4C,
There is a problem in that the durability of this linkage structure is greatly adversely affected by the repetition of the cycle of being rotated, seated, and added to the connecting pin 6, groove 2a, etc.).

In view of the conventional problems described above, the present invention rotates the eccentric bush so that the position of the center of rotation of the eccentric bush moves and changes with respect to the center of rotation of the rocker shaft.
In the compression pressure release type brake device in the engine, which is configured to open the valve of the engine through the rocker arm,
An object of the present invention is to prevent the eccentric bush from rotating along with the rocker arm swinging when the valve is opened / closed, and to improve the durability of the structure for linking the eccentric bush and the actuator.

[0010]

Therefore, the invention according to claim 1 is to provide a rocker shaft rotatably supported,
An eccentric bush that is rotatably fixed to the rocker shaft integrally and that has a center of rotation that is eccentric from the center of rotation of the rocker shaft; A rocker arm that oscillates as a body, an eccentric bush, an arm portion provided so as to extend from an outer peripheral portion of the eccentric bush, and an actuator that oscillates the arm in cooperation with the arm portion. By swinging the arm portion by the actuator, the eccentric bush is rotated so that the rotation center position moves and changes with respect to the rocker shaft rotation center, and the engine valve is opened via the rocker arm. In the compression pressure release type brake device in the engine, the arm portion of the eccentric bush is A preset spring that applies a predetermined preset load in the operation direction corresponding to the valve closing direction of the arm portion is provided, and the preset spring is engaged with the outer peripheral portion of the arm portion distal end side opposite to the actuator coupling portion. And a rocker that extends from the engaging portion along the outer peripheral surface of the arm portion and curvedly extends along the outer peripheral surface of the eccentric bush, and the other end portion is formed on a fixing portion provided on the side of the eccentric bush. It is formed in a substantially J-shaped linear shape which is rotatably supported in a support hole extending in the shaft direction.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 to 4, a compression pressure release type brake device in an engine is provided with a rocker shaft 1 that is rotatably supported, and a rocker shaft 1 that is integrally and rotatably fixed to the rocker shaft 1 and has a center of rotation of the rocker shaft 1. Is an eccentric bush 2 having an eccentric center of rotation,
A rocker arm 3 which is rotatably supported on the outer peripheral surface of the eccentric bush 2 and swings around the center of rotation of the eccentric bush 2, and the eccentric bush 2 is provided so as to extend from the outer peripheral portion of the eccentric bush 2. 2A, and a hydraulic cylinder device 4 as an actuator that cooperates with the arm portion 2A to swing the arm portion 2A. The hydraulic cylinder device 4 serves to move the arm portion 2A. By swinging the eccentric bush 2, the eccentric bush 2 is rotated so that its rotation center position moves and changes with respect to the rotation center of the rocker shaft 1.
It is the same as the conventional one in that the exhaust valve of the engine is opened via the.

Further, the operating rod 4A of the hydraulic cylinder device 4
The pin 6 fixed so as to traverse the groove 5 provided at the tip portion and the groove 2a formed at the tip portion of the arm portion 2A are engaged with each other to link the arm portion 2A and the hydraulic cylinder device 4. This is also the same as the conventional one. Here, a preset spring 7 that applies a predetermined preset load to the arm portion 2A of the eccentric bush 2 in the operation direction corresponding to the valve closing direction of the arm portion 2A is provided.

One end of the preset spring 7 is engaged with the outer peripheral portion of the arm portion 2A opposite to the connecting portion of the hydraulic cylinder device 4 on the tip end side, and the arm portion 2 extends from the engaging portion.
A support hole extending along the outer peripheral surface and curved along the outer peripheral surface of the eccentric bush 2 and having the other end extending in the direction of the rocker shaft 1 formed in the fixed portion provided on the side of the eccentric bush 2 It is formed in a substantially J-shaped linear shape that is rotatably supported by the.

In this case, the preset spring 7
Is arranged in a space formed by the eccentric bush 2, the boss portion 3A of the rocker arm 3, and the rocker bracket 8. And, one end of the preset spring 7 is
The engaging shaft portion 7A is bent into a substantially L shape to form an engaging shaft portion 7A. The engaging shaft portion 7A is a hole formed in an outer peripheral portion of the arm portion 2A opposite to the hydraulic cylinder device 4 connecting portion. 2b, the other end of which is bent and formed into a substantially L shape to form a rotation support shaft portion 7B. The rotation support shaft portion 7B serves as a fixed portion provided on the side of the eccentric bush 2. It is rotatably supported by a support hole 8A formed in the rocker bracket 8 and extending in the direction of the rocker shaft 1.

Next, the operation and effect based on this structure will be described. In this configuration, the arm portion 2A is
A predetermined preset load is applied by the preset spring 7 in the operation direction (direction of arrow F in FIG. 1) corresponding to the valve closing direction, and when the compression pressure release type brake device is turned off, the position is set to the position G in FIG. The preset spring 7 is activated when the compression pressure release type brake device is turned on.
It is rotated against the preset load by and is positioned at the position H in FIG. ON of this compression pressure release type brake device
At times, the rotation support shaft portion 7B of the preset spring 7 is
Since it rotates in the support hole 8A of the rocker bracket 8,
The displacement of the preset spring 7 is small.

As described above, the preset load is applied to the arm portion 2A of the eccentric bush 2 by the preset spring 7. As a result, the rocker arm 3 and the eccentric bush 2 which swing along the peripheral surface of the eccentric bush 2 when the exhaust valve is opened and closed. It is possible to prevent the eccentric bush 2 from rotating with the frictional force between them. In particular, when the compression pressure release type brake device is OFF, the piston 4B of the hydraulic cylinder device 4 (see FIG. 5 etc.)
The downward movement lowers the operating rod 4A (see FIG. 5, etc.), and the eccentric bush 2 rotates. At this time, even if the force to rotate the eccentric bush is applied to the eccentric bush 2, the preset load of the preset spring 7 is applied in the direction of arrow F in FIG. It is possible to prevent the accompanying rotation of 2.

As a result, it is possible to alleviate the impact force due to the repetition of the cycle of entrainment and seating of the exhaust valve, and it is possible to improve the durability of the linkage structure of the eccentric bush 2 and the hydraulic cylinder device 4. Further, as described above, when the compression pressure release type brake device is turned on, that is, when the hydraulic cylinder device 4 is lifted, the rotation support shaft portion 7B of the preset spring 7 has the support hole 8A of the rocker bracket 8.
The preset spring 7 has a small amount of displacement because it rotates. Therefore, the change in stress of the preset spring 7 is small, the durability of the preset spring 7 can be improved, and the load applied to the hydraulic cylinder device 4 at the time of lifting the hydraulic cylinder device 4 can be reduced. The influence on the responsiveness of the operation can be suppressed as much as possible.

Further, according to this structure, since the preset spring 7 can be disposed in the space formed by the eccentric bush 2, the boss portion 3A of the rocker arm 3 and the rocker bracket 8, the mountability can be improved. Are better. Incidentally, as a spring for applying a preset load to the eccentric bush 2, the leaf spring 9 as shown in FIG. 9 has good mountability, but when the compression pressure release type brake device is turned on, that is, the lift of the hydraulic cylinder device. At this time, since the amount of displacement of the leaf spring 9 is large and the stress change is large, the leaf spring 9 is inferior in durability, and the lift operation response of the hydraulic cylinder device is greatly affected.

A coil spring 11 as shown in FIG.
Then, when the compression pressure release type brake device is turned on, that is, when the hydraulic cylinder device is lifted, the coil spring 1
The stress change of 1 is small, but the mountability is poor. The pin 6 on the tip end side of the actuating rod 4A of the hydraulic cylinder device 4 and the groove 2a on the tip end side of the arm 2A are engaged to form the arm 2A.
The configuration in which the hydraulic cylinder device 4 and the hydraulic cylinder device 4 are linked to each other may be omitted, which eliminates the need for forming the notches in the pin 6 and the groove 2a, thereby reducing the cost.

[0020]

As described above, according to the invention of claim 1, as a result of applying a preset load to the arm portion of the eccentric bush by the preset spring, the preset load is applied along the peripheral surface of the eccentric bush when the exhaust valve is opened and closed. The rotation of the eccentric bush due to the frictional force between the rocker shaft and the eccentric bush, which swings, is prevented.In particular, when the compression pressure release type brake device is not in operation, the impact caused by repeating the cycle of rotation and exhaust valve seating The force can be relieved, and the durability of the linkage structure between the eccentric bush and the actuator can be improved. Further, when the compression pressure release type brake device is activated, the stress of the preset spring is less changed, the durability of the preset spring can be improved, and the load applied to the hydraulic cylinder device can be reduced. The effect on the performance can be suppressed as much as possible, and the mountability of the preset spring is also excellent.

[Brief description of drawings]

FIG. 1 is a schematic front view of an embodiment of the device of the present invention.

FIG. 2 is a view on arrow a in FIG.

FIG. 3 is a detailed plan view of the above embodiment.

FIG. 4 is a view on arrow b in FIG.

FIG. 5 is a schematic front view of a conventional device.

FIG. 6 is a view on arrow c in FIG.

7 is a view on arrow d in FIG.

FIG. 8 is a schematic front view of the conventional device.

FIG. 9 is a front view showing an example of taking out another preset spring having a problem.

FIG. 10 is a front view showing an example of taking out another preset spring having a problem.

[Explanation of symbols]

 1 Rocker Shaft 2 Eccentric Bushing 2A Arm 2b Hole 3 Rocker Arm 4 Hydraulic Cylinder Device 7 Preset Spring 7A Engagement Shaft 7B Rotation Support Shaft 8 Rocker Bracket 8A Support Hole

Claims (1)

[Claims] 1. A rocker shaft that is rotatably supported, an eccentric bush that is rotatably fixed to the rocker shaft integrally, and has a rotation center that is eccentric to the rocker shaft rotation center, and an eccentric bush outer peripheral surface. A rocker arm that is rotatably supported by the eccentric bush and swings around the center of rotation of the eccentric bush; an arm portion provided on the eccentric bush so as to extend from an outer peripheral portion of the eccentric bush; And an actuator that swings the arm to swing the arm portion. By swinging the arm portion by the actuator, the rotation center position of the eccentric bush moves and changes with respect to the rocker shaft rotation center. A compression pressure release type breaker in an engine that is rotated to open the valve of the engine through a rocker arm. In the device, a preset spring that applies a predetermined preset load to an arm portion of the eccentric bush in an operation direction corresponding to a valve closing direction of the arm portion is provided, and one end of the preset spring is a tip of the arm portion. Engages with the outer peripheral portion on the side opposite to the actuator connecting portion on the side of the portion, extends from the engaging portion along the outer peripheral surface of the arm portion, and extends curved along the outer peripheral surface of the eccentric bush, and the other end portion is eccentric. A compression pressure in an engine, which is formed into a substantially J-shaped linear shape that is rotatably supported in a support hole that is formed in a fixed portion that is provided on the side of the bush and that extends in the rocker shaft direction. Open brake device.