Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2000-02-28
2001-09-04
Shaver, Kevin (Department: 3754)
Fluid handling
Systems
Multi-way valve unit
C137S630000, C251S129160, C251S129190
Reexamination Certificate
active
06283154
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a control valve for a reservoir injection system for diesel engines. The control valve has a housing with a valve chamber, an inlet connection, an outlet connection, a return connection and a first valve body disposed in the valve chamber. Such a configuration is known from U.S. Pat. No. 5,407,131.
A diesel engine with direct injection is the internal combustion engine with the highest thermodynamic efficiency. With respect to the fuel injection, different technologies are employed for various engines. Systems with pressure intensification in the fuel injector are used, particularly in the commercial vehicle sector. An example of a fuel injector with pressure-intensifying transmission is described in U.S. Pat. No. 5,460,329. In this publication, the fuel reaches the pressure intensifier in the injector via an electromagnetic control valve configured as a spool valve. The fuel is put under high pressure by the pressure intensifier at fixed times or crank angles by use of electromagnetic activation of the control valve. In the conventional manner, the fuel put under high pressure then acts in such a way that the valve needle of the injector is raised from its seat and frees the path for the fuel to the injection nozzle so that the fuel is injected into the combustion chamber of the diesel engine.
Another type of control valve for a fuel injector with a cam-operated pressure intensifier is described in U.S. Pat. No. 5,407,131. In this case, the control valve is a seat valve, which is normally open and which can be closed with the aid of an electromagnet. In the open condition, the fuel supplied from the tank by a low-pressure fuel feed pump flows back through the control valve to the tank.
Fuel injection into the combustion chamber of a cylinder of the diesel engine is initiated by an electrical or electronic engine control activating the electromagnet of the control valve. The magnetic force generated by the electromagnet causes the control valve to close. The fuel in the injector, which can no longer drain away, is consequently put under pressure by the cam-actuated piston of the pressure intensifier. The injection begins when the pressure has reached the specified nozzle needle opening pressure. The fuel injection is ended by the electromagnet no longer being supplied with current. After the collapse of the electromagnetic field, the seat valve opens again so that the fuel can again drain away and the pressure in the injector falls.
The opening and closing of the seat valve naturally takes place in correlation with the positions and movements of the piston in the cylinder of the engine and of the pressure intensifier piston of the injector, which is in mechanical connection with the crankshaft.
An injection pump appliance is known from British Patent Specification GB 1 470 166, which describes a control valve for use in a fuel reservoir injection system with a fuel injector, upstream of which is fitted the control valve. The control valve has a housing with a valve chamber, in which an inlet connection and an outlet connection and a return connection are provided. An axially movable, first valve body, which forms a first seat valve (which selectively creates a fluid connection between the outlet connection and the return connection), is disposed in the valve chamber. In addition, a second valve body, which forms a second seat valve, is provided in the valve chamber of the control valve. The first seat valve is disposed between the outlet connection and the return connection and is normally closed. The second seat valve is disposed between the inlet connection and the outlet connection and is normally open.
The known configurations have the disadvantage that in the case of both the spool valves and the seat valves, the sealing function is insufficient. The spool valves are only insufficiently sealed over the sealing gap and, in the case of the seat valves, the sealing function is undertaken by the seat in one direction only.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a control valve for use in a reservoir injection system for a diesel engine which overcomes the above-mentioned disadvantages of the prior art devices of this general type, in which the sealing function is improved.
With the foregoing and other objects in view there is provided, in accordance with the invention, a control valve for use in a fuel reservoir injection system having a fuel injector with a pressure intensifier fitted upstream of the control valve, the control valve including:
a housing having a valve chamber formed therein, an inlet connection, an outlet connection, and a return connection;
a first valve body disposed and axially movable in the valve chamber, the first valve body forming a first seat valve which can selectively create a fluid connection between, the outlet connection and the return connection; and
a second valve body disposed in the valve chamber and forming a second seat valve, the first seat valve disposed between the outlet connection and the return connection and being normally closed, the second seat valve disposed between the inlet connection and the outlet connection and being normally open.
The above object is consequently achieved, in accordance with the invention, in that in the case of the control valve, which contains the housing with the valve chamber, the inlet connection, the outlet connection, the return connection and the first valve body which is axially movable in the valve chamber. The valve body forms a first seat valve that can selectively create a fluid connection between the inlet connection and the outlet connection or between the outlet connection and the return connection. The second valve body is provided and forms the second seat valve, the first seat valve is disposed between the outlet connection and the return connection and being normally closed and the second seat valve is disposed between the inlet connection and the outlet connection and being normally open.
The second valve body is advantageously configured coaxially in the first valve body. The second valve body can be connected to an armature plate, which is opposite to a magnet unit. In the case of an activation of the magnet unit, the second valve body moves first and closes the second seat valve before the first valve body, entrained by the second valve body, moves and opens the first seat valve.
The control valve according to the invention is, therefore, a pressure-balancing valve with two seat valves disposed one within the other. The two seat valves can be manufactured independently of one another. When the control valve is assembled, the two seat valves are then disposed in pairs and adjusted. The configuration provides the advantage of a functional improvement by pressure balance in each position of the valve. This minimizes the adjustment forces necessary. In addition, the two seat valves of the control valve according to the invention can be manufactured and adjusted independently of one another, so that the manufacture of the control valve is simple. The valve opening is variable, the two seat valves open and close one after the other and not together so that it is not necessary to take account of complex transition functions.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a control valve for use in a reservoir injection system for a diesel engine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying d
Augustin Ulrich
Giavi Raimondo
Rizk Reda
Greenberg Laurence A.
Keasel Eric
Lerner Herbert L.
Shaver Kevin
Siemens Aktiengesellschaft AG
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