Valves and valve actuation – Fluid actuated or retarded – Dashpot or fluid controlled retarder or timer
Reexamination Certificate
1999-10-19
2001-12-11
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
Dashpot or fluid controlled retarder or timer
C251S129190
Reexamination Certificate
active
06328276
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is based on a magnetic valve for a fluid-controlled heating and/or cooling installation.
Such magnetic valves are used particularly in fluid-controlled heat exchangers for heating and/or air conditioning systems of motor vehicles. They can be triggered in clocked fashion as a function of the temperatures in the kg or in a passenger compartment, and the flow is determined substantially by the mean time cross section. By means of the fluid pressure and/or a valve spring, the valve member of the magnetic valve is opened, and it is closed by an excited coil of the magnetic valve by acting on an armature connected to the valve shaft. The chamber in which the armature is disposed is not hermetically sealed but instead is filled with fluid. This is intended to damp the motion of the armature hydraulically, in order to avert an abrupt closure and attendant pressure surges in the fluid system. This also prevents both noise and wear that occur when the valve member strikes the valve seat without damping. The damping action is severely impaired, however, by gas and particularly air bubbles that collect in the armature chamber, for instance when the system is filled. The magnetic valves can also be used as reversing valves, which short-circuit the coolant flow from the internal combustion engine in a first switching position and in a second switching position cause it to flow via a heat exchanger.
From German Patent DE 195 370 67 C1, in a magnetic valve disposed in a forward flow line of a heat exchanger of a heating system, it is known, by using the pressure drop between the forward flow line and the return line, to cause a flow through the armature chamber of the magnetic valve, in order to remove the air bubbles from the armature chamber and to avert the attendant disadvantages. To that end, a venting line is provided between the armature chamber and the return line, while by way of an annular gap between the armature and the coil of the magnetic valve, fluid from a forward flow line flows into the venting line and prevents air bubbles from collecting in the armature chamber.
From German Patent DE 34 164 65, in a magnetic valve, it is also known to connect an armature chamber to a line segment located on the side of the valve member toward the armature chamber by way of an axial conduit in an armature shaft. The pumping action of the armature during the valve actuation is intended to positively displace air from the armature chamber and to aspirate fluid. Because of the compressibility of the air, however, a sufficient exchange of fluid does not always take place between the armature chamber and the line segment, and under some circumstances the air can remain trapped in the upper, annular portion of the armature chamber.
The valve member is guided axially limitedly displaceably in the valve shaft. By means of the fluid pressure, it is pressed in the opening position against a stop on the valve shaft. If the coil of the magnetic valve is excited, then the armature secured to the valve shaft is attracted, and the valve shaft presses the valve member against a valve seat. If the valve member strikes the valve seat undamped, it causes noise because of the impulse of the impact and increases wear.
SUMMARY OF THE INVENTION
According to the invention, on the side of the valve shaft toward the valve member, means are provided that slow down the speed of the valve shaft upon closure of the valve member. These may be elastic elements, which are connected between the valve member and the valve shaft and which decouple the mass of the valve shaft and the armature from the mass of the valve member. As a result, the impulse of impact of the valve member and thus wear as well as the closing noise are greatly reduced.
As elastic elements, springs of suitable design may be used, such as helical springs, leaf springs, cup springs, and springs of rubber, plastic, etc. They are simple, functionally reliable, and require no maintenance.
The valve member is guided axially limitedly displaceably relative to the valve shaft, in accordance with the spring travel. By means of the elastic element, the kinetic energy of the valve shaft and of the armature is stored and is then dissipated by the intrinsic damping behavior of the magnetic valve.
The valve member is pressed firmly against the valve seat by the valve shaft in the closing position, so that the closing function is assured, while in the opening position the valve member is lifted from the valve seat by the valve spring. However, the elastic element can also be designed as strong enough that the valve member is pressed securely against the valve seat by the elastic element in the closing position. In another variant, the elastic element can be designed so that the closing member is moved by the fluid pressure into the opening position and is pressed against the valve seat only when the magnet coil is excited. A further variant provides that the elastic element does not come into action until after a predetermined travel of the valve member and thus is opened by the fluid flow when the magnet coil is not excited, but is pressed against the valve seat by the elastic element as soon as the magnet coil is excited.
The speed of the valve shaft can also be reduced by a damping device that engages the valve shaft or the valve member. This damping device not only prevents the valve member or valve shaft from continuing to vibrate after the seating of the valve member but also already brakes the speed of the armature, valve shaft and valve member during the valve motion.
Since the means for slowing down the valve shaft are disposed on the side toward the valve member, the damping action in the armature chamber and the flow through the armature chamber can be largely dispensed with. If coolant does not flow through the armature chamber, then there is no risk of depositing abraded material and dust in the armature chamber and on the armature and the electromagnet, which would impair both the magnetic and the mechanical properties of the magnetic valve.
The damping device is formed in a simple way by a disk secured to the valve shaft that is moved in a fluid-filled part of the valve housing. In some cases, it may suffice for the damping disk to be disposed in a flow conduit, but the action can be improved if it is guided with a slight play from a separate damping chamber that is sealed off from the outlet conduit by a diaphragm seal. Upon the motion of the damping disk, fluid is positively displaced from one side of the damping disk to the other via an annular gap. The damping performance can be adapted by means of additional throttle bores in the damping disk.
In order not to substantially increase the masses in motion of the magnetic valve by means of the mass of the damping disk, it is expedient for the disk to be thin and made from a lightweight material, such as lightweight metal or plastic. These materials furthermore have no effect on the magnetic performance of the magnetic valve.
In order to assure that the damping chamber is always filled with fluid, in a feature of the invention fluid can be exchanged between the damping chamber and the outlet conduit via a throttle restriction.
REFERENCES:
patent: 2621015 (1952-12-01), MacGregor
patent: 3737141 (1973-06-01), Zeuner
patent: 4114125 (1978-09-01), Komatsu
patent: 4364541 (1982-12-01), Chabat-Courrede et al.
patent: 4878650 (1989-11-01), Daly et al.
patent: 4932434 (1990-06-01), Taylor
patent: 5443241 (1995-08-01), Odaira et al.
patent: 5791630 (1998-08-01), Nakao et al.
patent: 5810330 (1998-09-01), Eith et al.
patent: 195 37 067 C1 (1996-08-01), None
patent: 34 16 465 C2 (1996-09-01), None
patent: 2 580 557 (1986-10-01), None
Falch Peter
Fellmann Heinrich
Heier Christoph
Hess Juergen
Pfetzer Johannes
Keasel Eric
Robert & Bosch GmbH
Senn Jeanette
Shaver Kevin
Striker Michael J.
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