Internal-combustion engines – Engine speed regulator – Responsive to deceleration mode
Patent
1996-10-18
1997-10-14
Nelli, Raymond A.
Internal-combustion engines
Engine speed regulator
Responsive to deceleration mode
F02D 1304
Patent
active
056761090
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention is based on a hydraulic system which can be used, in particular, as an engine brake for an internal combustion engine.
Such a hydraulic system is known in its use as engine brake from Federal Republic of Germany 41 21 435 A1. In that case, a so-called decompression valve is associated with each cylinder of the internal combustion engine, the valve being actuated outside the exhaust cycle of the working piston of a cylinder and in particular at the end of the compression cycle, by the action of pressure on a hydraulic piston serving as actuating member. The source of pressurized fluid for the system is a positive-displacement pump, in particular a radial piston pump, by which pressurized fluid can be pumped from a low-pressure region into a high pressure region. A distributor unit has a number of control outputs which corresponds to the number of decompression valves, each of said control outputs being connected by a control line to a hydraulic piston. When operated as a brake, the control outputs are pressurized via the distributor unit from the high pressure and connected to the low pressure with a cycle time which is linearly dependent on the speed of rotation of the internal combustion engine. The dependence of the cycle time on the speed of rotation of the internal combustion engine is obtained, for example, in simple fashion in the manner that the distributor unit has a distributor rotor which is turnable with respect to the control outputs and is driven, via a step-down transmission, directly by the internal combustion engine with half the speed of rotation of the latter.
In practical tests on a model, it was found that the desired intensity of the braking action is not obtained at all speeds of rotation of the internal combustion engine. Within these speed ranges, the amount of pressurized fluid pumped by the positive displacement pump used is not sufficient to maintain the desired pressure in the high-pressure region. In principle, it is possible to use a positive displacement pump of greater displacement. This, however, has the result that, upon normal operation of the internal combustion engine, and therefore when braking is not to be effected, and the high-pressure region is relieved of pressure, the positive displacement pump absorbs a high motoring power which reduces the useful output of the internal combustion engine. On the other hand, within speed ranges in which previously the amount of pressurized fluid pumped by a smaller positive displacement pump had been sufficient, a large amount of oil flows off via the pressure-limiting valve which controls the pressure in the high-pressure region and is strongly heated thereby. New problems can result from this.
SUMMARY OF THE INVENTION
The object of the present invention, therefore, is to improve a hydraulic system which is used, in particular, as engine brake for an internal combustion engine and has the features set forth in the preamble to claim 1, in such a manner that, while retaining a positive displacement pump of relatively small displacement over the entire range of the cycle times in which the control outputs are acted on by pressure and relieved of pressure, the desired control of the actuating elements is retained and, therefore, the desired braking action can be obtained over the entire speed range of the internal combustion engine when the hydraulic system is used as engine brake.
This object is achieved in accordance with the invention by a hydraulic system which has the features set forth in the preamble to claim 1 and, in addition, in accordance with the body of claim 1 has a return valve which opens towards the high-pressure region and via which the control line leading from a control output to an actuating element can be disconnected from the high-pressure region upon the end of its pressurization and connected to the high-pressure region before its connection to the low-pressure region.
The invention first of all is based on the idea that a control line is pressu
REFERENCES:
patent: 4936273 (1990-06-01), Myers
patent: 5495838 (1996-03-01), Johnson, Jr.
patent: 5595158 (1997-01-01), Faletti et al.
patent: 5603300 (1997-02-01), Feucht et al.
patent: 5609134 (1997-03-01), Schmidt et al.
Eisenbacher Egon
Unger Manfred
Willig Burkhard
Farber Martin A.
Mannesmann Rexroth GmbH
Nelli Raymond A.
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