MXPA01002631A - Engine compression brake system - Google Patents

Abstract

An engine compression braking systemincludes an exhaust rocker arm pivotally supported on rocker shaft. One end of the rocker arm carries a roller which engages a camshaft which has a lost motion bump formed thereon. The other end of the rocker arm engages an exhaust valve stem assembly. A part of the rocker shaft engages a pressure operated piston. Extension of the piston moves the rocker shaft transversely to its axis, so that the rocker arm can selectively react to or ignore the lost motion portion bump. A pressure control system includes a solenoid operated valve controlled by an operator controlled switch, so that the piston selectively applies a light force or a very high force to the rocker arm rocker shaft, thus controlling the pivot point of the rocker arm.

Description

COMPRESSION BRAKE SYSTEM FOR ENGINE BACKGROUND OF THE INVENTION The invention relates to a compression braking system for a motor, and in particular, to a motor braking compression system of the type in which the pivot center of the oscillating exhaust arm is displaced.

Various types of compression braking system for motor are known. In a type of engine compression brake system, a lost motion device is included on one end of the swing arm or on the links that connect the swing arm to the cam lobe or valve (push lever or lifter) to allow a control mechanism by reacting or ignoring a part of the profile of the cam lobe. Another type of engine compression brake system is shown in U.S. Patent No. 5,647,319, issued in 1997 to Uehara et al. And in U.S. Patent No. 3,367,312, issued in 1966 to Jonsson Both of these systems have motor brake mechanisms in which the pivot center of the oscillating exhaust arm is displaced or changed by an eccentric which is connected to a hydraulic piston / actuator by means of a lever arm.

However, these mechanisms require an extra mechanical component between the hydraulic piston / actuator and the oscillating arm. Also, the various actuator arms and levers of these systems are subject to stress and bending loads, which increase the probability of voltage faults. These additional links, arms and actuators also increase the manufacturing tolerance requirements of many of the components. These systems also require intermediate arms, a second eccentric wobble arm hole, accessories at the small end of the pivot arm / actuator and accessories at the mechanical actuator end of the piston. All these parts and accessories increase the cost and complexity, and reduce the reliability of the system. Finally, these systems result in an assembly which is not as compact as desired, and will result in an increase in the height of the engine.

Synthesis of the invention Therefore, an object of this invention is to provide a compression brake mechanism for motor with few components.

A further object of the invention is to provide such a motor compression braking mechanism wherein the parts are not subject to tension and bending loads.

A further object of the invention is to provide such a motor compression brake mechanism which does not increase the manufacturing tolerance requirements for many of the components.

A further object of the invention is to provide such a motor compression brake mechanism with reduced complexity, low cost and an increase in the reliability of the system.

A further object of the invention is to provide such a motor compression brake mechanism which prevents an increase in the height of the motor.

These and other objects are achieved by the present invention, wherein a motor compression brake system includes an oscillating swing arm pivoted on an oscillating shaft. One end of the oscillating arm carries a roller which engages the camshaft which has a lost motion pump formed therein. The other end of the oscillating arm engages a set of exhaust valve stem. A part of the oscillating shaft engages a piston operated under pressure. The extension of the piston moves the oscillating shaft transversely to its axis, so that the oscillating arm can selectively react or ignore the part of the lost motion pump. A pressure control system includes a solenoid-operated valve controlled by an operator-controlled switch, so that the piston selectively applies a light force or high force to the oscillating shaft of the swing arm, thereby changing the pivot point of the arm. oscillating.

BRIEF DESCRIPTION OF THE DRAWINGS The only figure is a view of a motor compression brake system according to the present invention.

Detailed description Referring to the single figure, the engine compression brake system 10 includes an oscillating exhaust arm 12 pivoted by an oscillating shaft 14 which is received by the bore of the oscillating shaft 15. The oscillating shaft 14 has a diameter of which is smaller than that of the orifice of the oscillating shaft 15 by a small amount such as 0.030 inches. One end of the oscillating arm 12 carries a roller 16 which engages a camshaft 18 which has a lost motion pump 20 formed therein. The other end of the swing arm 12 engages an exhaust valve stem assembly 22. Due to the pressure of the springs the valve stem assembly 22, normally the swing arm 12 may be engaged with the underside of the oscillating shaft 14. , observing the figure. The swing arm 12 includes a tongue 24 which projects from it. The tongue 24 has a partially cylindrical convex outer surface 26. A piston 28 engages the tongue 24 and has a cylindrical concave surface 29 which engages the convex surface 26 of the tongue 24.

The piston 28 is slidably received in an orifice of the piston 30 formed in a box 32, which is preferably part of the piston box of a diesel engine (not shown). The piston 28 and an orifice wall 30 enclose a pressure chamber 34. The pressure in the chamber 34 is preferably controlled by a pressure control assembly 36, also preferably enclosed in the box 32, as it is known from "FAQs: Motor Brake Theory ", by Jacobs Vehicle Systems, 1996.

The pressure control assembly 36 preferably includes a solenoid-operated valve (not shown), and energization of the solenoid valve is controlled by a switch controlled by the operator 46, which is preferably connected to the vehicle battery 48 a through a fuel pump switch 50, the clutch switch 52 and the fuse 54. The pressurization of the pressure chamber 34 causes the piston 28 to move towards the oscillating shaft 14 and therefore move the central part of the arm oscillating 12 until the wall of the hole 15 engages an upper part of the oscillating shaft 14, thereby changing the pivot axis of the swing arm 12.

Therefore, this system 10 uses electronically controlled hydraulics to control the pivot that positions the oscillating exhaust arm 12 for braking or retarding the engine. Controlling the pivot position of the exhaust swing arm 12 allows the selective transfer of some or all of the movement / profile of the exhaust lobe of the camshaft 18 to be transferred to the exhaust valve stem assembly 22. The selective transfer of some or all movements of the cam lobe to the valves, together with the fuel level of the engine, determines the ability of the engines to generate a positive energy or absorb it (brake) energy.

The extension of the piston 28 moves the pivot point of the oscillating arm transversely to its axis, so that the oscillating arm 12 can selectively react or ignore the lost motion pump 20. The pressure in the piston 28 can be controlled so that the piston 28 selectively apply a light force or very high force to the swing arm 12, thereby controlling the pivot point of the swing arm 12. A light piston force allows the swing arm 12 to operate in its normal location, such as when the engine (not shown) is under load. This normal position prevents the swing arm 12 from reaching the lost movement pressure 20, and the forces that are transmitted to the exhaust valve assembly 22, since the lost movement pressure 20 is small enough to "get lost" in space of the valve set. A high piston force displaces and keeps the swing arm 12 down against the upper part of the oscillating shaft 14, causing the swing arm 12 to react to the lost motion pump 20, and to transmit forces to the exhaust valve assembly 22 , since the oscillating arm 12 has an effective zero valve clearance space.

The previous system does not have an extra mechanical component between the hydraulic piston actuator and the oscillating arm, which results in improved function, reliability and reduced cost. Because the piston 28 exerts a compression force on the oscillating arm 12, bending loads are avoided and the probability of failure is reduced. Few parts result in components of requirements under manufacturing tolerance other than the orifice, hydraulic piston and orifice of the oscillating arm. Finally, this design allows to have a compact motor of low height.

Although the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations may be apparent to those skilled in the art in light of the foregoing description. Therefore, this invention is intended to encompass all those alternatives, modifications and variations which fall within the spirit and scope of the appended claims.

Claims (6)

1. - A motor compression braking system having an oscillating arm held in pivot fashion on an oscillating shaft shaft, a piston responsive to the pressure operatively coupled to the oscillating arm and a pressure control system for controlling the pressure of fluid applied to the piston, the movement of the piston causes the movement of a pivot shaft of the oscillating arm, characterized in that: the piston has an end face which directly contacts a part of the swing arm.

2. - The engine compression braking system as claimed in clause 1, characterized in that: the oscillating arm includes an appendage which projects from it and makes contact with the end face of the piston:

3. - The motor compression arm system as claimed in clause 1, characterized in that: the oscillating arm includes an appendage projecting therefrom, the appendage having a convex and arcuate outer surface; Y the piston has an arcuate concave surface which coincidentally makes contact with the convex surface of the appendix.

4. - The engine compression braking system as claimed in clause 1, characterized in that: normally the oscillating arm will be in contact with a lower part of the oscillating axle, and pressurization of the pressure chamber causes the piston to move the piston. oscillating arm to make contact with the upper part of the oscillating shaft.

5. - In a motor compression braking system having an oscillating arm held in a pivot on an oscillating shaft, a piston responsive to the pressure operatively coupled to the oscillating arm, and a pressure control system for controlling the pressure of fluid applied to the piston, the movement of the piston causes the movement of a pivot shaft of the oscillating arm, characterized in that: the oscillating arm normally engages a first side of the oscillating shaft, and the piston can move in response to the fluid pressure to move the oscillating arm to contact a second side of the oscillating shaft, said second side is oriented essentially opposite to said first side.

6. - The engine compression braking system as claimed in clause 5, characterized in that: the oscillating arm includes an appendage projecting therefrom, the appendage having a convex and arcuate outer surface; Y the piston has an arcuate concave surface which engages coincidently with the convex surface of the appendix.