US 3625476 A
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United States Patent Inventor Hans Meier Remscheid, Germany Appl. No. 868,41 1 Filed Oct. 22, 1969 Patented Dec. 7, 1971 Assignee Joh. Vaillant KG.
Remscheid, Germany Priority Dec. 23, 1968 Germany P 18 16 558.7
VALVING ARRANGEMENT 1 Claim, 3 Drawing Figs.
US. Cl 251/129, 25 Ill l, 236/75, 236/46 F Int. Cl F26k 31/02 Field of Search 236/68, 46 F, 75, 78, 68 A, 68 B, 68 C, 68 D, 68 R, 78 A, 78 B, 78 C References Cited UNITED STATES PATENTS 3/1969 Yoder 25l/l29 X Primary Examiner-Meyer Perlin Assistant Examiner-W. C. Anderson Auorney- Darbo, Robertson & Vandenburgh ABSTRACT: A valve operator includes an electric motor moving the valve in one direction and working against a spring which moves the valve in the other direction. The energizing circuit for the motor includes an on-off switch and a temperature-dependent semiconductor. The semiconductor is connected to provide graduated energization of the motor during one of the valve movements. In one embodiment the semiconductor is in parallel with the switch and has a positive temperature coefficient. in another embodiment the semiconductor is in series with the switch and has a negative temperature coefficient. In the latter embodiment a second switch is in parallel with the semiconductor and this switch is normally open, but is closed after the motor is energized and upon its moving the valve to the fully open position.
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' fi zva M51512 017% m VALVING ARRANGEMENT BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to a valving arrangement comprising a valve operable by means of an electromechanic motor against a restoring force and a switch in the electric circuit of the electric motor of the valve.
Frequently, it is necessary to retard the changeover movement of the valve upon closing or opening of the switch in order to avoid valve impacts and disturbing noise. For this purpose braking devices or speed controllers are known to be provided. Arrangements of this type are, however, quite expensive.
It is an object of the present invention, in a valving arrangement of the type mentioned hereinbefore to effect a nonimpacting changeover of the valve by simple means.
According to the present invention this object is attained by providing a temperature-dependent semiconductor resistor in the electric circuit of the motor with respect to the switch contact in a manner retarding the switching movement of the motor and such that its current-defined temperature changes in a manner reducing the retarding effect.
Temperature-dependent semiconductor resistors of the type indicated are known per se. They are characterized by either a substantial increase (positive temperature coefficient, PTC, resistors) or very substantial decrease (negative temperature coefiicient, NTC, resistors) in their electric resistance with a rising temperature. The temperature increase is occasioned by current flow through the resistor. Such resistors are arranged in the electric circuit of the motor in such a manner that they first tend to counteract the effect intended by the actuation of the switch contact, that is switching-oh or switching-on of the motor. However, they are connected so that in one of the switch positions of the switch contact a current flows through the semiconductor resistors and thus the temperature of the respective semiconductor resistor changes in a manner reducing the retarding client.
In one embodiment of the present invention, the circuit arrangement is such that a valve can be changed over from a first into a second position by an electric motor against the action of a spring and when the motor is switched off, it and the valve return into the first position, and that a PTC-resistor is connected in parallel with the switch. With such an arrangement a radiator may, for instance, be disconnected from a heating water circuit by the valve and be bridged by a short circuit line. This is accomplished by means of a valve controlled by a room thermostat. When the thermostat contact is opened, the motor initially continues to be supplied with cur rent through the FTC-resistor since the resistance value of the PTC-resistor is relatively small when cold. However, as soon as current flows through the FTC-resistor, the latter is heated, and its resistance value is thereby increased. Accordingly, the power to the motor is slowly reduced. As the power of the motor decreases in relation to the force of the restoring spring, the valve is slowly changed over by the restoring spring. When the surplus of force of the restoring spring is sufficient, the valve slowly assumes the operating position corresponding to the deenergized state of the motor.
The FTC-resistor further increases its internal resistance up to a value which only permits an inconsequential residual current to flow through the motor. When the valve is to be again changed over, the switch contact isagain closed. In the closed position, the switch serves as a shunt across the FTC-resistor robbing the resistor of current. The FTC-resistor thereupon cools off and reassumes its initial low-resistance state.
Such an arrangement may also be utilized to effect a changeover from heating circuit to domestic water circuit in a circulation heating system with domestic water supply.
In another embodiment, the resistor (in this instance an NTC-resistor) is connected in series with the solenoid (motor) of a solenoid valve which valve also actuates a second switch in parallel with the solenoid. The purpose is to achieve a gradual movement of the solenoid armature and therewith a constant actuation of the solenoid valve. Upon the initial closing of the motor control switch, there is a relatively high resistance (of the NTC-resistor) in series with the motor and motor control switch. With the current flow occurring after the closing of the switch, the NTC-resistor is heated and its resistance value reduced. Thereby, a steady increase in the current through the solenoid coil (motor) of the solenoid valve is obtained.
In a further modification of the invention, the NTC-resistor is bridged by an auxiliary contact closing upon full excitation of the solenoid coil. Thus, when the solenoid valve is actuated, the NT C-resistor will be shunted and will again cool off. Thereby it is ready to produce the same effect upon the next following actuation.
If necessary, the invention permits the use of a solenoid valve without a braking device, with a restoring spring or restoring springs providing a nonlinear characteristic of the restoring force. Thereby, it is possible to achieve a temporary retention of the opening movement of the valve, after a first stage of the characteristic has been passed through, and thereafter provide full opening of the valve.
DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates schematically a first embodiment of the invention including a radiator connected to the flow and return of a heating system;
FIG. 2 represents another state of setting of the valve of FIG. 1; and
FIG. 3 illustrates another embodiment of the invention including a solenoid valve.
DESCRIPTION OF SPECIFIC EMBODIMENTS The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.
A radiator l is connected to the flow and return conduits Vf and Rf, respectively, of a heating circuit through a three-way valve 3. The three-way valve 3 is controlled by a room thermostat switch 2 by means of a motor 4 working against the action of a spring 5. In a first state of the solenoid valve (FIG. 2) the radiator l is disconnected from the heating circuit and bridged by a sport-circuit conduit K. When the switch 2 of the thermostat closes, the motor 4 causes the valve 3 to change from the first into the second state against the action of the spring 5. A FTC-resistor is connected in parallel with the switch 2 of the thermostat. When contact 2 is closed, the resistor is shunted and has inconsequential current flowing through it. Therefore, it is relatively cold. When the switch opens, a flow of current to the motor 4 through the FTC-resistor will be obtained. Initially, this flow of current is relatively large, as the PTC-resister has a relatively low resistance value at low temperature. However, as the PTC-resistor is heated by the flow of current through it, its resistance value will increase. The flow of current decreases accordingly. To the extent that the flow of current through the motor 4 decreases, the spring 5 overcomes the power of the motor 4 and gradually changes the valve 3.
While with the embodied form according to the FIGS. 1 and 2 the operating voltage of a considerable is slowly reduced by means of a FTC-resistor, thus, the motor power slowly decreases until the restoring force of the spring changes over the valve, in the embodied form according to FIG. 3 the operating voltage of a solenoid valve motor 6 is slowly built up against the force of a retarding device 9. This is accomplished in that the resistance of the NTC-resistor connected in series with the solenoid constantly decreases due to self-heating, until the motor force overcomes the forces counteracting the opening stroke. The retarding forces are primarily provided by the closing spring of the valve and the braking device 9. For solenoid valves with delay in starting it is desired that a specific working stroke is passed through during a preestablished period of time, whereby a certain dosage of the medium flowing through the valve 8 will be obtained. It is known to achieve this delay in starting through the use of a brake piston. Thereby, relatively large variations result. This is due to the fact that the magnetic force is dependent, to a considerable extent, on the temperature of the solenoid coil and on the voltage. However, since the braking device must effect the desired retention also for maximum magnetic force, a correspondingly large braking device is required. With the control according to the present invention, including an NTC-resistor, the operating voltage and therewith the magnetic force are built up slowly. Thereby, the working range of the braking device is considerably reduced. The braking device 9 can be smaller and less expensive. It may possibly be omitted altogether, if either the valve spring has a suitable characteristic, or is comprised of two springs becoming active one after the other, so that the opening movement of the valve is temporarily retained, after the first spring stage has been passed through, and only thereafter full opening of the valve is caused.
In parallel connection to the NTC-resistor is a switch 7 which is closed, when the solenoid valve 8 is fully open. When closed, switch 7 shunts the NTC-resistor allowing it to cool off.
When the switch 2, perhaps the switch of a thermostat, is closed, an electric current flows from the terminal R through the NTC-resistor and the solenoid coil 6 to the terminal Mp. At the start the resistor is cold and its resistance is relatively high. As a result, initial voltage at the solenoid 6 is so low that the magnetic field is not yet sufficient to overcome the counterforce provided by the closing spring (not shown in F IG. 3) of the valve 8 and the braking device 9. The electric current, however, heats the NTC-resistor so that its internal resistance is continuously reduced. Hence, the electric current flowing through the solenoid coil 6 correspondingly increases and therewith the magnetic field, until the magnetic field is sufficient to overcome the counterforces and the valve is slowly opened. When fully open, the solenoid armature closes switch 7 to shunt the NTC-resistor so that the latter cools off and is ready for another switch-on in the same manner.
1. In an apparatus comprising a valve actuated by an electric motor working against a spring and an energizing circuit connected to said motor with a switch in said circuit in series with the motor so that when said switch is actuated to the closed position, after being open, said motor is energized to move the valve in one direction and when said switch is actuated to the open position, after being closed, said valve is moved in the other direction by the spring the improvement comprising:
means connected in said circuit for retarding the valve movement upon the opening of said switch, said means comprising a temperature-dependent semiconductor having a positive temperature coefficient connected in parallel with said switch whereby when the switch is closed the semiconductor carries little current due to the switch forming a short circuit across it and the semiconductor develops a relatively low resistance and when the switch is thereafter opened the semiconductor increases in temperature and resistance from its initially low resistance as a consequence of the current flow through it.
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