JPH09256828A - Decompression brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always provide optimum decompression brake effect by arranging a lever member provided with an eccentric bush between a rocker arm and a rocker shaft in an exhaust valve and deflecting the lever member by means of a deflection actuator. SOLUTION: A lever member 6 provided with an eccentric bush 5 is arranged between a rocker arm 4 and a rocker shaft 2. When the lever member 6 is rotated around the rocker shaft 2, a valve opening quantity in a valve closing action can be varied by means of the rocker arm 4. In the vicinity of a final process of the valve closing action, a valve opening quantity of the exhaust valve is maintained, so that decompression brake effect can be exhibited. For holding the lever member 6 in the displaced condition to an eccentric cam 7, an actuator 8 is arranged, and an eccentric cam shaft 9 for rotating the eccentric cam 7 is rotated by means of a cam shaft driving actuator in compliance with an engine rotational speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decompression brake device, and more specifically, it is applied to a diesel engine mounted on a vehicle during engine braking,
The present invention relates to a decompression brake device that can be appropriately controlled according to the engine speed.

[0002]

2. Description of the Related Art A conventional decompression brake device is disclosed in, for example, Japanese Utility Model Laid-Open No. 4-19637. In this conventional example, a cylinder head of the engine is equipped with a power tard valve which is connected to an exhaust port in addition to an intake / exhaust valve. A possible cam member and a spring that biases the stopper member toward the cam member are provided, and the position of the stopper member in the stroke direction is displaced by driving the cam member according to high speed rotation and low speed rotation of the engine. It is a thing. Therefore, due to such displacement of the stopper member in the stroke direction in the working chamber, the valve lift, that is, the valve opening amount during decompression braking of the power-tard valve at high speed rotation and low speed rotation of the engine becomes appropriate. I try to keep it.

[0003]

However, in the above-mentioned conventional example, since the cam member for displacing the stopper member comes into contact with the annular stopper member at its eccentric position, the stopper member tends to be inclined with respect to the stroke direction. It is easy to cause malfunctions. Further, since the spring, the stopper member and the cam member are incorporated in the working chamber of the actuator, and the stroke direction of the actuator and the stroll direction of the power tard valve are in series, the length of the actuator main body becomes long and the device itself The height becomes bulky.

Further, the control of the valve lift of the power-tard valve is almost limited to two types, that is, high speed operation and low speed operation, and it is constructed so as to be controlled in multiple stages or continuously according to the engine speed. It has not been.

It is an object of the present invention to pay attention to the above-mentioned conventional problems and to solve them, there is no possibility of malfunction occurring,
An object of the present invention is to provide a decompression brake device that is compact and that is controlled so that an optimum decompression brake effect is always obtained according to the engine speed.

[0006]

In order to achieve the above object, the present invention provides a decompression brake device for maintaining an opening amount in a closed state of an exhaust valve, the rocker arm and the rocker shaft of the exhaust valve. And a lever member having an eccentric bush capable of displacing the rocking center of the rocker arm, and a cam member that is rotatably held by a cam shaft and that keeps contact between the lever member and the cam surface. A lever actuator that biases the lever member toward the cam surface, and a cam shaft drive actuator that rotates the cam shaft. The cam shaft drive actuator rotates the cam shaft to rotate the lever member. By rotating the rocker arm around the rocker arm and displacing the rocking center of the rocker arm through the eccentric bush. It is characterized in that the amount of opening of the optimum in accordance with the number of revolutions was obtained.

Further, according to the present invention, for continuous control according to the number of revolutions of the engine, the cam shaft drive actuator is rotated by hydraulic pressure, and a hollow cylindrical rotary vane member for rotating the cam shaft, A rotary valve that is rotatably fitted in the hollow portion of the rotary vane member and is related to the supply of the hydraulic pressure, and a pulse motor that rotates the rotary valve. The pulse motor is driven to rotate the engine. It is characterized in that the valve opening amount can be continuously changed by controlling according to the number.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the present invention, a lever member having an eccentric bush is rotated around a rocker shaft by a cam, whereby the rocking center of the rocker arm is displaced and driven by the rocker arm. By changing the regulation amount of the closing stroke of the exhaust valve, it becomes possible to easily and stably perform continuous control according to the engine speed when the decompression brake is used.

Embodiments of the present invention will be described in detail and specifically below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment according to the present invention.
Note that this example is an example of application to an internal combustion engine having two exhaust valves for each cylinder, and in FIG. 1A, reference numeral 1 denotes a rocker shaft 2 supported by a cylinder head 10 shown in FIG. 1B. The support brackets 3 and 4 are rocker arms swinging around the rocker shaft 2, 3A and 4A are abutted on the top of the valve rod, respectively, and arm portions involved in opening and closing an exhaust valve (not shown), 3B and 4B are valve clearances. It is an adjusting screw that is involved in adjustment.
Of the rocker arms 3 and 4, 4 is a rocker arm involved in the decompression brake device of the present invention, and the rocker arm 4 is provided between the rocker arm 2 and the rocker shaft 2 with respect to the rocker shaft 2 as shown in FIG. A lever member 6 having an eccentric bush 5 which is eccentric and is rotatable about the lever is interposed.

6A is the lever portion, 7 is an eccentric cam that keeps contact with the upper surface of the lever portion 6A, and 8 is the plunger portion 8A that abuts on the lower surface of the lever portion 6A so that the lever portion 6A faces the eccentric cam 7. It is an actuator that keeps it displaced. Reference numeral 9 denotes an eccentric cam shaft for rotating the eccentric cam 7, and the eccentric cam shaft 9 is rotatably supported by the shaft supporting portion 1A of the support bracket 1.

In the decompression brake device having such a structure, by rotating the lever member 6 around the rocker shaft 2, the rocker arm is fitted concentrically with the lever member 6 and is kept swingable. The valve opening amount at the time of valve closing operation by 4 can be made different. By the way, in the vicinity of the final stroke of the valve closing operation, the decompression brake action is known in which the exhaust valve is not brought into the completely closed state and the valve opening amount is maintained to contribute to the deceleration of the engine. It is known that the optimum valve opening amount and the engine speed in such a case have a relationship as shown in FIG. Therefore, in the present embodiment, the eccentric cam shaft 9 is rotated by a cam shaft drive actuator (not shown) in accordance with the engine speed to maintain the minimum valve opening amount in the state shown in FIG. The amount of opening of the exhaust valve by the rocker arm 4 is maximized by keeping the rocking position of the lever member 6 by the eccentric cam 7 at a maximum while the eccentric cam shaft 9 is rotated approximately 180 ° from this state. It can be controlled to be kept.

Next, referring to FIGS. 3 and 4, the eccentric cam 7 is shown.
A configuration example of a cam shaft drive actuator that drives the motor will be described.

The cam shaft drive actuator described below is a rotary valve type electromagnetic actuator. Specifically, by controlling the rotary drive of a pulse motor according to the rotation speed of the engine, the cam shaft drive actuator is driven according to the rotation of the rotary valve directly connected to the motor. Is to be rotated to a free rotation angle. In FIG. 3, 21 is a step motor, 22 is a direct connection to the step motor 21, and is a hollow rotary valve rotated by the motor 21, and 23 is fitted on the outer peripheral surface of the rotary valve 22 and is rotatably held. Sagging, 2 radially formed on the outer periphery of itself
A rotary vane member having a single vane 23A, and 24 is a valve housing.

Both ends of the valve housing 24 are closed by covers 25A and 25B, and partition members 24A and 24A fixed to the inner peripheral wall of the housing 24 are attached to the inner surface of the valve housing 24. The facing space in the valve housing 24 defined by the partition members 24A, 24A further has a vane 23 in which the peripheral portion of the rotary valve 23 is sealed.
As shown in FIG. 4, the oil chambers A and 23A are separated into two oil chambers D and E whose volumes change. Also,
As shown in FIG. 4, the rotary valve 22 is provided with a first oil passage 22A and a second oil passage 22B, while the rotary vane member 23 has a first oil hole 26A and a second oil hole in both side cylinders of the vane 23A. 26B is provided. Further, in FIG. 1, 27 is a support member for fixedly supporting the rotary valve type electromagnetic actuator having the above-mentioned structure on the engine body side together with the valve housing 24 and the covers 25A and 25B, and 28 is a support member for supporting the eccentric cam shaft 11 on the actuator side. Bearing member.

The rotating operation of the eccentric cam shaft 11 by the electromagnetic actuator will be described with reference to FIGS. 4 (A) and 4 (B).

Here, assuming that FIG. 4A is an operation for controlling the valve opening amount at low engine speed, for example, FIG. 4B shows the valve opening amount at high engine speed. This means that the operation for control is in progress. Further, the oil chambers D, D and E, E, which are located at mutually opposite positions, communicate with each other, and in the rotary valve 22, the suction side chamber and the discharge side chamber are separated by a wall in a direction orthogonal to the plane of the drawing. Oil is supplied to and discharged from the suction-side chamber and the discharge-side chamber via a hydraulic pressure supply system and a discharge system (not shown), respectively.

Now, when the rotary valve 22 is rotated by the step motor 21 shown in FIG. 3 in the direction shown by the dashed arrow in FIG. 4A, the rotation of the rotary valve 22 causes the first oil passage 22A to rotate. Vane member 23
The hydraulic pressure introduced into the rotary valve 22 from the state where it first coincides with the first oil hole 26A is introduced into the oil chamber D, and as shown by the white arrow, the hydraulic pressure drives the rotary vane member 23 via the vane 23A. Rotate in the counterclockwise direction. Further, when the oil pressure is supplied to the oil chamber D as described above, the second oil hole 26B of the rotary vane member 23 is aligned with the second oil passage 22B of the rotary valve 22, so that the oil chamber E inside the rotary valve 22 is provided. The oil is discharged to the discharge side chamber and further discharged to the outside of the actuator. Then, when the rotary vane member 23 is rotated, the eccentric cam shaft 9 directly connected thereto is rotated.

If the rotary valve 22 is kept in the position shown in FIG. 4A, for example, the rotation of the rotary vane member 23 by hydraulic pressure causes the first oil passage 22A and the second oil passage 22A to rotate.
The rotary vane member 2 is configured such that the position of the oil passage 22B and the positions of the first oil hole 26A and the second oil hole 26B are cut off from each other, for example, at a position where the vane 23A is indicated by a broken line.
The rotation of the eccentric cam shaft 9 can be maintained as it is.

Furthermore, when it is desired to rotate the eccentric cam shaft 9 in the opposite direction, the rotary valve 22 is rotated clockwise by the step motor 21 (see FIG. 3) as indicated by the broken line arrow in FIG. 4B. It may be rotated in the direction. By such a rotating operation, the first oil passage 22A and the second oil passage 22B of the rotary valve 22 are moved to the first oil hole 26A and the second oil hole 26B of the rotary vane member 23.
The hydraulic pressure can be supplied to the oil chamber E from the time when it starts to coincide with, and the rotary vane member 23 can be rotated as shown by the white arrow. In addition, the rotary valve 22 is, for example, as shown in FIG.
Rotating vane member 2 that rotates when it remains in the position shown in
The rotation operation of the vane 3 can be stopped when the vane 23A reaches the position shown by the broken line.

As described above, by controlling the rotation of the step motor 21 in accordance with the number of revolutions of the engine, the valve opening amount of the exhaust valve related to the decompression brake can be freely controlled, and It is also possible to control the valve opening amount as an example when the compression brake is not required.

Further, it goes without saying that the rotary valve type electromagnetic actuator and the eccentric cam shaft as described above do not necessarily have to be directly connected, and for example, a gear or a clutch may be interposed therebetween. . Furthermore,
By appropriately setting the positions and sizes of the oil passages and the oil holes provided in the rotary valve 22 and the rotary vane member 23, it is possible to freely select the responsiveness and speed during brake operation.

Further, according to this embodiment, the torque fluctuations transmitted to the rotary vane member 23 and the drive shaft of the step motor 21 via the cam shaft 9 are received by the hydraulic pressures supplied to both oil chambers D and E. The camshaft 9 can always be kept in a stable state.

In the above embodiment, the rotary valve type electromagnetic actuator is described as a preferred example of the actuator for rotating the cam shaft 9, but the actuator is not limited to this, and the cam shaft is of course not limited thereto. The rotary solenoid or the step motor may be directly used as long as it is configured to sufficiently receive the reaction from the rotary solenoid.

The hydraulic pressure used for driving the cam shaft and for holding the lever member may be the hydraulic pressure generated for circulating the engine lubricating oil, and a hydraulic pressure generating means is specially provided for the actuator itself. You don't have to.

[0026]

As described above, according to the present invention, a lever member which is interposed between a rocker arm and a rocker shaft of an exhaust valve and which has an eccentric bush capable of displacing the rocking center of the rocker arm, is provided. A cam member that is rotatably held by a cam shaft and that keeps the lever member and cam surface in contact with each other; a bias actuator that biases the lever member toward the cam surface; and a cam that rotates the cam shaft. A shaft drive actuator, wherein the cam shaft is rotated by the cam shaft drive actuator to rotate the lever member around the rocker arm, and the rocking center of the rocker arm is displaced through the eccentric bush. As a result, the optimal valve opening amount can be obtained according to the engine speed, so the valve opening amount during decompression braking can be adjusted. It is possible to obtain a high engine braking force over speed range general engine it is possible to optimally control according to the rotation speed of the gin. Also,
The entire device is compact, and the stable braking operation is guaranteed with less risk of malfunction.

Furthermore, by using a rotary valve type electromagnetic actuator as the actuator for driving the cam shaft, more stable control of the apparatus is guaranteed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a configuration according to the present invention by a top view (A) and a side view (B).

FIG. 2 is a characteristic curve diagram showing a relationship between an engine speed and an optimum opening amount of an exhaust valve related to a decompression brake.

FIG. 3 is an exploded perspective view showing a configuration example of an actuator for a decompression brake device according to the present invention.

4A and 4B are explanatory views showing a rotating operation in two directions by the actuator shown in FIG. 3 by sectional views of FIGS.

[Explanation of symbols]

 2 rocker shaft 3,4 rocker arm 3A, 4A arm part 5 eccentric bush 6 lever member 6A lever part 7 eccentric cam 8 actuator 8A plunger part 9 (eccentric) cam shaft 10 cylinder head 21 step motor 22 rotary valve 22A, 22B oil passage 23 Rotating vane member 23A vane 24 Valve housing 24A Partition member 26A, 26B Oil hole D, E Oil chamber

Claims (3)

[Claims] 1. A decompression brake device for maintaining a valve opening amount in a closed state of an exhaust valve, wherein the decompression brake device is interposed between a rocker arm and a rocker shaft of the exhaust valve to displace a rocking center of the rocker arm. A lever member having a possible eccentric bush, a cam member that is rotatably held by a cam shaft and that keeps the lever member and the cam surface in contact, and a bias actuator that biases the lever member toward the cam surface. A cam shaft drive actuator for rotating the cam shaft, wherein the cam shaft is rotated by the cam shaft drive actuator to rotate the lever member around the rocker arm, and through the eccentric bush. By displacing the rocking center of the rocker arm, the optimum valve opening amount can be obtained according to the engine speed. Decompression braking device comprising and. 2. The decompression brake device according to claim 1, wherein the cam member is an eccentric cam. 3. The camshaft drive actuator is rotated by hydraulic pressure to rotatably fit into a hollow cylindrical rotary vane member that rotates the camshaft, and a hollow portion of the rotary vane member. A rotary valve relating to the supply of the hydraulic pressure and a pulse motor for rotating the rotary valve are provided, and the valve opening amount is continuously controlled by controlling the drive of the pulse motor according to the rotation speed of the engine. The decompression brake device according to claim 1, wherein the decompression brake device is changeable.