Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Utility Patent
1999-08-23
2001-01-02
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
C251S030010, C123S467000, C123S496000, C239S096000, C239S124000, C239S533700, C239S533900
Utility Patent
active
06168132
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the mechanical arts. Specifically, the invention relates to a valve operated with a control valve and, more particularly, to an injection valve with a control valve. The injection valve has a housing formed with a control chamber and a control piston which bounds the control chamber and is displaceable within the housing. A feed supplies the control chamber with pressure medium, in particular fuel, and the pressure medium flows out of the control chamber via a drain. A closing member is associated with a sealing seat of the drain and opens or closes the drain. A control device is arranged outside the control chamber and is operatively connected with the closing member. The sealing seat is formed on the high-pressure side and the closing member is disposed on the high-pressure side. The closing member is connected to a valve rod, which is passed through the drain, and which is operatively connected with the control device. The closing member is disposed in the control chamber, and the closing member is preloaded against the sealing seat with a spring means arranged outside the control chamber.
Injection valves with a control valve are used, for example, in a common rail injection system in order to control the pressure in a control chamber. The pressure in the control chamber acts via a control piston on an injection needle which rises from a valve seat as a function of the pressure, with the result that fuel is injected into an internal combustion engine.
U.S. Pat. No. 5,381,999 to Ricco (EP 0 604 915 A1) discloses an injection valve with a control valve in which a control chamber is connected via a restrictor to a drain controlled by a control valve. The control valve has a closing member which is associated with a valve seat formed at the end of the restrictor. The closing member is pressed onto the valve seat from the low-pressure side by spring elements. An electromagnet is provided to raise the closing member from the associated valve seat, thereby starting an injection process. However, that prior art injection valve is subject to the disadvantage that the restrictor is opened if the spring elements break.
European published patent application EP 0 826 876 A1, which is the most closely related prior art, describes an injection valve with a control valve which has a closing member that is associated with a valve seat and is connected to a piston which in operative connection with an actuator. The piston is partially enclosed by an annular spring holder with which a spring element is in operative connection in such a way that the closing member is pressed onto the valve seat from the low-pressure side via the piston. The closing member and the valve seat are mounted on the high-pressure side.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an injection valve with a control valve, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which reliably closes the drain restrictor of the control chamber.
With the foregoing and other objects in view there is provided, in accordance with the invention, an injection valve, comprising:
a housing formed with a control chamber;
a control piston bounding the control chamber and being displaceably disposed in the housing;
a feed conduit communicating with the control chamber for supplying the control chamber with a pressure medium;
a drain communicating with the control chamber for draining pressure medium out of the control chamber, the drain being formed with a sealing seat on a high-pressure side;
a closing member disposed in the control chamber on the high-pressure side and being operatively associated with the sealing seat of the drain for selectively opening and closing the drain;
a control device outside the control chamber and operatively connected with the closing member;
a valve rod connected to the closing member, passing through the drain, and being operatively connected with the control device;
a spring holder connected to the valve rod on the low-pressure side, the spring holder being formed as a sleeve with a hollow space and a bottom plate at one end thereof, the bottom plate being connected to the valve rod and being associated with the drain;
a spring member clamped outside the control chamber between the spring holder and the housing for preloading the closing member against the sealing seat; and
an actuator piston operatively connected with the control device and inserted into the hollow space of the sleeve.
It is a primary advantage of the invention that the closing member of the control valve is arranged on the high-pressure side and is pressed against the valve seat by the pressure in the control chamber. A further advantage resides in the fact that the closing member reliably closes the drain even if the preloading system are damaged.
In accordance with an added feature of the invention, the bottom plate is formed with an opening, the valve rod passes into the opening, and the valve rod is connected to the bottom plate in an upper region of the bottom plate.
In accordance with an additional feature of the invention, the drain is formed as a flow restrictor.
In accordance with another feature of the invention, there is provided a plate formed with an opening defining the drain, formed with a second recess adapted to partially accommodate the spring holder, and formed with a first recess at least partially forming the control chamber and defining the sealing seat.
In accordance with a further feature of the invention, a shape of the closing member is matched to a shape of the control chamber for minimizing a control volume of the control chamber.
In accordance with a concomitant feature of the invention, there is provided a control-valve unit that comprises the following elements:
a plate having the drain formed therein;
the closing member and the valve rod extending through the drain;
the spring holder with the valve rod connected thereto;
the spring element clamped between the spring holder and the plate and preloading the closing member against the sealing seat, wherein a spacing distance between the closing member and the spring holder is fixed at a predetermined value for setting a maximum stroke of the closing member.
It is a further advantage of the invention that the closing member is connected by a small diameter valve tappet to an actuator piston which has a larger diameter. The valve tappet is passed through a drain conduit which has a correspondingly small diameter. Owing to its large diameter, the actuator piston has a high rigidity, allowing the closing member to be moved precisely and rapidly by an actuator which controls the actuator piston. Since the drain hole has a small diameter, the closing member can also be of correspondingly small design, so that only a small force is necessary to move the closing member against the pressure in the control chamber and to thereby open or close the drain hole.
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 an injection valve with control valve, 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 drawings.
REFERENCES:
patent: 4544128 (1985-10-01), Kolchinsky et al.
patent: 4674688 (1987-06-01), Kanesaka
patent: 4993637 (1991-02-01), Kanesaka
patent: 5271599 (1993-12-01), Kolchinsky et al.
patent: 5526791 (1996-06-01), Timmer et al.
patent: 5538187 (1996-07-01), Mueller et al.
patent: 5664545 (1997-09-01), Kato et al.
Frank Wilhelm
Lewentz G{umlaut over (u)}nter
Rink J{umlaut over (u)}rgen
Schmutzler Gerd
Vendulet Joachim
Bastianelli John
Greenberg Laurence A.
Lerner Herbert L.
Shaver Kevin
Siemens Aktiengesellschaft
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