Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Patent
1998-06-09
2000-07-11
Kamen, Noah P.
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
123323, F02D 2300
Patent
active
06085524&
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for controlling the engine braking effect in an internal combustion engine in a motor vehicle, which is equipped with a compression braking device, means for varying the degree or charge in brake mode, comprising, firstly, an exhaust-driven turbocompressor unit with a turbine portion and a compressor portion, and secondly, valve means disposed in engine exhaust conduit, and means actuatable by the driver of the vehicle for activating the compression braking device and the means for varying the degree charge.
BACKGROUND OF THE INVENTION
It is known that the engine braking power of a vehicle can be increased with the aid of a device or the above described type, by means of which the engine combustion chambers in brake mode during the latter portion of the compression stroke is connected to the exhaust system, for example by opening the regular exhaust valve. The result will be that the air compressed during the compression stroke flows out of the cylinders and that the compression work carried out during the compression stroke will not be recovered during the expansion stroke, and this will result in an increase in the engine braking power. An additional increase in the braking power can be achieved in this case in a known manner by connecting the exhaust system to the cylinders during the latter portion of the induction stroke, so that gas from the exhaust system can flow into the cylinders. This results in an increase in pressure in the cylinder and an inner charging so that the compression work after breaking off the communication between the cylinders and the exhaust system will be increased.
In a device known by SE-A-9401059 of the type described by way of introduction, said valve means are formed of an exhaust pressure regulator (EP regulator), i.e. a damper in the exhaust line downstream of the turbine portion of the turbocompressor unit. By varying the degree of opening of the damper, the driver can control the degree of inner charging and thus increase or reduce the braking power. The damper is controlled by a control unit into which the driver feeds a desired value of the vehicle retardation and into which engine data is fed via sensors such as the degree vehicle retardation and into which engine data is fed via sensors such as the degree of charge and the rpm, and vehicle data such as vehicle speed, accelerator position and clutch pedal position.
SUMMARY OF THE INVENTION
The purpose of the present invention is in general to achieve a device of the type described by way of introduction which makes it possible to achieve higher braking power in the engine than what could be achieved with the described device. The particular purpose is to achieve a device in which the turbocompressor unit can be utilized in a better manner together with the valve means in the exhaust line to vary the braking power of the engine.
This is achieved according to the invention by virtue of the fact that the valve means are restrictor valve means arranged in the engine exhaust conduit upstream of the turbine portion of the turbocompressor unit.
By placing the valve means closer to the exhaust outlet from the cylinders, there is a reduction in the volume of the exhaust conduit between the exhaust valves and the valve means in the exhaust conduit, which means that the pistons will not need to exhaust as much gas as previously in order to create a certain counter-pressure. High counter-pressure can therefore be obtained more rapidly.
In a turbocharged engine with an exhaust pressure regulator downstream of the turbine, the pressure drop required over the turbine, so that the turbine will be able to drive the compressor, cannot be obtained in brake mode. By instead placing the restrictor valve means prior to the turbine portion and adapting the restriction area to the turbine area, the turbocompressor unit can provide supercharging even in brake mode. It is true that the pistons are imparted energy from the gas during the induction stroke, but the work whi
REFERENCES:
patent: 4474006 (1984-10-01), Price et al.
AB Volvo
Kamen Noah P.
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