US3532331A

US3532331A - Gas valve control

Info

Publication number: US3532331A
Authority: US
Inventors: Gerald J Kushner
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1968-09-12
Filing date: 1968-09-12
Publication date: 1970-10-06
Anticipated expiration: 1987-10-06

Description

Oct. 6, 1970 I G. J. KUSHNER 3,

GAS VALVE CONTROL Filed Sept. 12, 1968 2 Sheets-Sheet 2 INVENTOR. GERALD J. KUSHNER mww HIS ATTORNEY United States Patent O 3,532,331 GAS VALVE CONTROL Gerald J. Kushner, Louisville, Ky., assignor to General Electric Company, a corporation of New York Filed Sept. 12, 1968, Ser. No. 759,420 Int. Cl. F2719 7/00 US. Cl. 26333 6 Claims ABSTRACT OF THE DISCLOSURE A gas flow control arrangement includes a solenoid valve and a bimetal valve placed in series in the gas flow path to a burner. The heater for the bimetal valve and the operating coil for the solenoid valve are connected in the control circuit to be energized and de-energized simultaneously.

BACKGROUND OF THE INVENTION In many installations of gas fueled burners it is desirable that the flow control arrangement have two valves, arranged serially in the gas flow path, so that both valves must be open for gas to flow. In the event one of the "valves sticks open, the other one will still close and stop the gas flow. The normal approach in the past has been to use two solenoid-type valves. Such installations are very expensive. They also require complicated control circuits to insure that residual magnetism does not cause both valves to stick open simultaneously.

A general object of the present invention is to provide an improved gas flow control arrangement for a gas fueled burner which is not subject to the foregoing disadvantages; and a more specific object is to provide such an improved arrangement which uses one solenoid valve and one bimetal valve.

Another object of my invention is top rovide an improved gas flow control arrangement particularly suited for use in gas heated fabric dryers such as domestic clothes dryers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a fabric dryer suitable for incorporation of the present invention, the view being partly broken away and partly in section to illustrate details; and

FIG. 2 is a schematic electric circuit diagram of a basic or simplified control for the dryer of FIG. 1, incorporating one embodiment of the present invention and including a schematic representation of a series arrangement of a solenoid valve and a bimetal valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the machine illustrated is a domestic clothes dryer generally indicated by the numeral 1. The dryer 1 is provided, in the usual way, with a cabinet 2 having a front door 3 for access to the interior of the cabinet to load and unload fabrics. Provided on the top wall 4 of the cabinet 2 is a control panel 5 which may include a suitable manual control 6 connected to a control assembly 7 mounted in the panel 5. By manual presetting of control 6, the machine may be caused to start automatically and proceed through a cycle of operation.

Within cabinet 2 there is provided a clothes tumbling chamber, or drum, '8 mounted for rotation on a substantially horizontal axis. Drum 8 is generaly cylindrical in shape, having a first, center cylindrical Wall portion 9, and second and third, outer cylindrical wall portions 10 and 11, located respectfully adjacent an annular front wall 12 and a circular rear wall 13 of the drum. Wall 3,532,331 Patented Oct. 6, 1970 portions 9, 10 and 11 are imporforate so that the outer shell of the drum is imperforate. On the interior surface of wall portion 9, there are a plurality of clothes tumbling ribs 14 so that clothes are lifted up when the drum rotates, and then tumble back down to the botom of the drum. The front of drum .8 may be rotatably supported within outer casing 2 by suitable idler wheels, one of which is indicated at 15. These wheels are rotatably secured to the top of a member 16 which extends up from the base 17 of the machine. The wheels are disposed beneath the drum, in contact with portion 10 thereof so as to support portion 10 on each side.

The rear end of drum 8 receives its support by means of a stub draft 18 extending from the center of wall 13. Shaft 18 is secured within a bearing 19 formed in a battle like member 20 which, in turn, is rigidly secured to the back wall 21 of cabinet 2 by any suitable means such as by welding at a number of points 22. With the arangement shown, the drum may rotate about a horizontal axis with rollers 15 providing the front support and stub draft 18 within bearing 19 providing the rear support.

In order to provide for the flow of a stream of drying air through the dryer, the drum is provided with a central aperture 23 defined by the front wall 12 and with a plurality of perforations 24 in rear wall 13. The perforations 24 in the present case are formed to extend around the rear wall in an annulus. The air provided to the drum is heated by a gas flame which issues from the outlet 25 of a gas burner 26. Burner 26 receives a regulated supply of gas from a gas flow control or a valve assembly generally indicated at 27, the gas being supplied to the assembly 27 from a suitable source (not shown) connected to inlet connection 28.

Primary air is drawn into the burner 26 at the inlet and 29 thereof and combustion occurs as a result of the mixture of this primary air and gas being ignited by an appropriate igniter 30. The outlet end 25 of the burner 26 is positioned just within a combustion chamber 31 so that secondary air is drawn in through end 32 of chamber 21 and is heated to a high temperature. The outlet end 33 of chamber 31 communicates with an upwardly extending duct 34, which is provided with additional air openings 35 in order to reduce the temperature of the air and gas mixture to an appropriate extent. The heated mixture (hereinafter called heated air) flows up through duct 34 and enters a generally circular heat diffuser chamber 36 formed between the member 20 and a baffle 37, which is rigidly secured to the outer surface of wall 13. Bafile 37 has openings 38 formed therein so that the heated air may flow from chamber 36 through openings 38 and perforations 24 into the drum 8.

The front opening 23 of the drum is substantially closed by means of a stationary bulkhead generally indicated by the numeral 39. The bulkhead 39 is made up of a number of adjacent members; including the inner surface 40 of the access door 3; a stationary frame 41, formed as a flange of the front wall '42 of the cabinet; the inner surface member 43 of an exhaust duct formed by the cooperation of number 43 with the front wall 42 of the cabinet and an annular flange 44, formed on the frame 41 of front wall 42. It will be noted that a suitable clearance is provided between the inner edge of central aperture 23 and the edge of bulkhead 39 so that there is no rubbing between the drum and the bulkhead during rotation of the drum. In order to prevent a substantial air leakage through this clearance space, a suitable ring seal is secured to flange 44 in sealing relationship to the exterior surface of drum wall 12.

Central aperture 23, in addition to serving as part of the air flow path through the drum, also serves as a means whereby clothes may be loaded into and unloaded from the drum. Door 3 is mounted on cabinet 2 so that when the door is opened clothes may be inserted into and/or removed from the drum through the door frame 41. It will be noted that the door includes an outer, flat and imperforate section 46 and an inwardly extending, hollow section 47, mounted on the flat outer section. Hollow section 47 extends into the door frame 41 when the door is closed, and the door surface 40, which comprises part of the combination bulkhead 39, is actually the inner wall of the hollow section.

The air outlet from the drum is provided by a perforated opening 48 formed in the inner wall of hollow door section 47. The bottom wall section of door 3 and the adjacent wall of door frame 41 are provided with aligned

openings

49 and 50. Opening 50 provides an entrance to the duct 51 formed by the cooperation of member 43 with front wall 42. As shown, a lint trap 52 is positioned in the exhaust duct 51 and opening 50 and is supported by the door frame 41.

Bust 51 leads downwardly and communicates with a housing 53. Housing 53 contains a blower 54 which is directly driven by a motor 55. The blower draws the heated air in from duct 51 and then exhausts it from the cabinet 2 through an appropriate duct (not shown). In addition to driving blower 54, motor 55 constitutes the means for effecting rotation of drum 8. In order to effect this rotation, motor 55 is provided with a shaft 56 having a small pulley 57 formed at one end thereof. A belt 58 extends around pulley 5-7 and also entirely around the cylindrical wall section 9 of drum 8. The relative circumferences of pulley 57 and wall section 9 cause the drum to be driven by the motor at the speed suitable to effect tumbling of the clothes therein. For proper tensioning of belt 58 there is provided a suitable idler assembly 59, secured to the same support 60 which supports one end of the motor. Thus, the air is pulled through the drum and, at the same time, the fabrics in the drum are tumbled. The air is heated by the flame emitted by the burner 26 and the heated air passing through the drum causes vaporization of moisture from the clothes. The vapor is carried off with the air as it passes out of the machine.

Referring now to FIG. 2, there is shown therein a schematic electric circuit diagram illustrating a simplified or basic control arrangement for the dryer of FIG. 1 and incorporating one embodiment of the present invention. It will be understood that many refinements such as temperature selection means, multiple cycle selection means, etc., have not been shown in the circuit of FIG. 2 as they do not form a part of the present invention.

The control includes a pair of conductors and 66 adapted to be connected to a suitable source of electric energy. For domestic use this normally will be a 115 volt power supply. The main motor 55 of the machine is a single-phase, induction-type motor having a main winding 67 and a start winding 68, both connected at a common end through a conventional motor protector 69 to a conductor 70. The conductor 70 is connected to one side of a door switch 71, which has its other side connected to the supply conductor 66. The door switch is open when the door 3 is open and is closed when the door is closed.

The start winding 68 and the main winding 67 are connected in parallel under the control of the speed responsive device 72, which is responsive to the rotation of the rotor of motor 55. The speed responsive device 72 controls a switch 73 which is engageable with

contacts

74 and 75, being engaged with contact 74 when the machine is at rest and moving into engagement with contact 75 as the motor comes up to speed. Engagement with contact 74 connects start winding 68 in parallel with main winding 67, while movement of switch 73 away from this position opens the start winding. Thus, as the motor comes up to speed, the start winding is de-energized and the motor then continues to run on main winding 67 alone.

Starting of the motor is provided by a manually operable switch 76 which, for instance, in the structure of FIG. 1 may be moved to its closed position by pulling out on the manual control 6. Switch 76 connects the motor to a conductor 77 which, in turn, is connected to the supply conductor 65 through a switch 78. Switch 76 is normally biased to its open position as shown; however, when the manual control 6 is pulled out, and providing

switches

71 and 78 are closed, energization of the motor is provided. Within less than a second, under normal circumstances, the motor 55 comes up to speed so that switch 73 moves from contact 74 and engages contact 75. This forms a bypass around the switch 76 for the main winding 67 and the motor 55 continues to be energized when the manual control 6 is released and switch 76 opens.

As indicated by the dash line 79, the switch 78 is under the control of a timer motor 80. The timer motor may also be connected to the manual control 6 so that rotation of the manual control will cause the timer motor to rotate and thus close the switch 78 to provide power to the control circuit. The operation of the machine is terminated when the timer motor has rotated a sufiicient amount to open the switch 78. It will be noted that the timer motor is connected on one side to the conductor 77 and on the other side to the conductor 66 so that it is energized any time the switch 78 is closed.

The control of gas flow to the burner 26 and its ignition is accomplished by the following circuit. Starting at the conductor 77, the circuit proceeds to a conventional thermostat 81 which is normally closed and opens in response to an excessively high temperature in the machine so as to prevent overheating. From the thermostat 81 one branch circuit extends through the bimetal switch arm 82 of a warp switch, also having a bimetal heater 83, to a conductor 84. The conductor 84 is connected to the switch 85 of a relay, also having a coil 86. The outer side of the switch 85 is connected by a conductor 86 to one side of the coil 87 of a solenoid valve 88. The other side of the coil 87 is connected by a conductor 89 to a switch 90, which also is controlled by the timer motor 80. The switch 90 is connected to the conductor 70 through a switch 91, which is controlled by the speed responsive device 72 so that the switch 91 is closed only when the motor 55 is rotating at operational speed.

From the thermostat 81 another branch circuit extends through the warp switch heater 83, the relay coil 91a, a conductor 92, a flame sensor 93, and a conductor 94 to the conductor 89. As seen in FIG. 1 the flame sensor 93 is positioned to sense the ignition of the air and gas mixture being emitted by the burner 26. The flame sensor is normally closed, as illustrated in FIG. 2, so that current flows through the heater 83 and the coil 91a. However, upon ignition of the air and gas mixture, the flame sensor quickly opens so as to de-energize these two elements. The bimetal arm 82 of the warp switch is normally closed, as shown; however, after a predetermined period of heating caused by current flow through the heater 83, it will open to tie-energize the circuit. This period is designed to be substantially longer than ignition normally takes so that the warp switch serves as a safety device to turn off the flow of gas in the event of a malfunction which has prevented ignition.

From conductor 84 a branch circuit extends through a conductor 95 to the motor 96 and then the contacts 97 and 98 of the igniter 30. A conductor 99 connects contact 98 to conductor 92. With this branch circuit, so long as the warp switch arm 82 is closed and the flame sensor 93 is closed the igniter will be energized. The contacts 97 and 98 are biased closed and the motor 96 opens them. Since there is current flow through the contacts a spark is emitted. The opening of the contacts also de-energizes the motor 96 so that the contacts are returned to the closed position. This process is repeated to provide sparks at the burner 26 until the gas and air mixture is ignited to open the flame sensor 93 or until the bimetal arm 82 of the warp switch opens.

Another branch circuit is provided by a conductor 100 which extends from the conductor 84 to one side of a heater 101 for the arm 102 of a bimetal valve, generally indicated at 103. The other side of the heater 101 is connected by a conductor 104 to the conductor 89. A dropping resistor 105 is connected between the conductor 100 and the conductor 8-6.

The housing schematically illustrated at 106 provides a series arrangement for the solenoid valve 88 and the bimetal valve 103 in the path of flow for the gas for the burner 26. This housing defines a passage indicated generally at 107 which has an entrance 108 adapted for connection to a suitable source of a combustible gas. From 108 the passage extends past the seat 109 formed for cooperation with a plunger 110 of the solenoid valve 88. A spring 111 biases the plunger 110 to the closed position preventing gas flow past the seat 109. Energization of the coil 87 pulls the plunger upward, as seen in FIG. 2, against the force of the spring so that gas may flow past the seat 109.

From the solenoid valve, the passage extends to a seat 112 formed for cooperation with a valve head 113 mounted on the bimetal arm 102. The bimetal arm normally is in the position shown, so that the head 113 closes the seat 112. The heating effect of heater 101, when energized, causes the bimetal arm 102 to deflect upwardly, as seen in FIG. 2, so as to move away from the seat 112 and allow gas flow thereby. Downstream from the bimetal valve, the housing defines an outlet 114 including a control orifice 115, which controls the maximum rate of gas flow. The outlet 114 is adapted for connection to the gas burner 26. Thus, it will be seen that gas will flow to the burner 26 only when both the solenoid valve 88 and the bimetal valve 103 are energized.

Bimetal valves normally have a fairly uniform time constant for a complete cycle of operation. That is, the time that it takes them to open once the heater is energized plus the time it takes them to close once the heater is de-energized is constant. However, the components may be varied. It is possible to have the bimetal valve open in a very brief time, in which case it will require a longer time for it to close. On the other hand, the valve may be designed to open slowly, in which case it will close rapidly. For use with the present invention the bimetal valve should be designed so that it opens rapidly, resulting in a relatively slow closing time. The fast opening time is required for the bimetal valve to be used in the control arrangement so that it will open and the gas will begin to flow before the warp switch opens to de-energize the circuit. Under normal conditions de-energization of the circuit will cause the solenoid valve 88 to close to turn off the gas flow. The bimetal valve functions as a redundant or safety valve in the event the solenoid valve fails to function and its relatively slow closing time will still be fast enough to prevent emission of excess gas.

For a typical cycle of operation the user would open the door 3, load the fabrics desired to be dried in the drum 8, then close the door 3, which closes the switch 71. The user then would rotate the manual control 6, which rotates the timer 80 to close the

switches

78 and 90. Then, the user would pull out on the manual control 6, closing the switch 76. Initially the main motor 55 will start on both the main winding 67 and the start winding 68. When the motor comes up to speed, the speed responsive device 72 moves the switch arm 73 from contact 74 to contact 75 to disconnect the start winding 68 and to form a connection around switch 76 so that the motor continues to operate on the main winding alone when the manual control 6 is released. Until the main motor 55 comes up to speed there can be no gas provided to the machine because switch 91 must be closed by the speed responsive device to complete the circuit for the control arrangement.

Once the switch 91 is closed a circuit is completed through the thermostat 81, switch arm 82, switch 85, and conductor 86 to the solenoid coil 87, then from the coil 87 through the conductor 89, switch 90 and switch 91 to 6 conductor 70; and then through the door switch 71 back to the supply conductor 66. Thus, the coil 87 will be energized to move the plunger 110 upwardly against the force of the spring 111 so that gas may flow past the seat 109.

At the same time a circuit is forced from the conductor 77 through the thermostat 81 and bimetal switch arm 82 to the conductor 84, then through the conductor 100 to the bimetal heater 101 and then from the heater 101 through the conductor 104 to the conductor 89. Thus, the bimetal heater 101 is energized and very quickly the bimetal arm 102 deflects upwardly to move the valve head 113 away from the seat 112 so the gas may flow past the seat 112.

The gas is mixed with air in the burner 26 and this gas and air mixture flows from the end 25 of the burner. The circuit for the igniter 30 is complete from the conductor 84 to the igniter motor 96 and the igniter contacts 97 and 98 back to the conductor 102; then through the flame sensor 93 and conductor 94 to the conductor 89. The igniter causes a repeating spark to occur at the outlet end of the burner 26, which will ignite the air and gas mixture.

Until ignition occurs a circuit is completed from the thermostat 81 through the warp switch heater 83 and the relay coil 91a and the conductor 92 to the flame sensor 93. Once the igniter has caused the air and gas mixture to ignite, the flame sensor 93 quickly opens. This deenergizes the igniter, the heater 83 and the coil 91a. Deenergization of the coil 91a causes the switch to open so that the circuit for the solenoid valve now extends from the conductor 84 through the conductor 84 through the conductor 100, and the dropping resistor 105 to the coil 87. Solenoid valves normally require a relatively large voltage to be applied to their coil in order to initially overcome the biasing spring and open the valve, However, once the valve is opened a lower voltage will effectively hold it open and such lower voltage reduces the heating effect on the valve. By use of dropping resistor 105 such a lower holding voltage is provided.

The energizing circuit for the bimetal valve remains the same. Thus, the two valves remain open in series in the gas flow path and gas is provided to the burner.

This operation continues and gas is provided to the burner to heat the air which is drawn through the drum 8 as it is rotated, so that the fabrics in the drum are dried. After a pre-determined period of drying the timer motor 80 causes the switch to open. This completely deenergizes the circuit for the

valves

88 and 103 so that first the solenoid valve closes to turn off the gas supply, then shortly thereafter the bimetal valve closes.

The main motor continues to run for a relatively brief period thereafter so that the clothes are tumbled while a stream of cool air is drawn through the dryer to reduce the temperature of the fabrics to a comfortable handling level, then the timer motor causes switch 78 to open, completely de-energizing the control circuit and turning off the machine.

It will be understood that a very simple fabric drying control circuit has been illustrated and many elements such as automatic temperature controls, multiple cycle selection arrangements and fabric temperature or resistance responsive arrangements for turning off the machine have been omitted for the sake of clarity, since they form no part of the present invention.

Thus, while in accordance with the patent statutes, there has been described what at present is considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without depart ing from the invention, and it is applicants intention in the appended claims to cover all such variations as fall within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. For use with a device having a gas fueled burner, a gas flow control arrangement comprising:

(a) two valves connected in series in the path of flow of the gas for allowing gas to flow only when both valves are open;

(b) one of said valves being a normally closed solenoid valve and including a coil for opening the valve when connected to a source of electric energy;

(c) the other of said valves being a normally closed bimetal valve and including heating means for causing the valve to open when connected to a source of electric energy;

((1) a circuit including means for simultaneously connecting and disconnecting said coil and said heating means to and from a suitable source of electric energy; and

(e) said bimetal valve being constructed to have a fast opening time compared to its closing time.

2. For use with a device having a gas fueled burner, a

gas flow control arrangement comprising:

(a) two valves connected in series in the path of fiow of the gas for allowing gas to flow only when both valves are open;

((1) a circuit including means for simultaneously connecting and disconnecting said coil and said heating means to and from a suitable source of electric energy;

(e) said coil and said heating means being connected in parallel in said circuit; and

(f) said circuit also including means for connecting a droping resistance in series with said coil after said one valve is open to reduce the voltage applied thereto to a valve still sufiicient to maintain it open.

3. The invention as set forth in claim 2 wherein said control includes sensing means, responsive to a flame at the burner, to effectively connect said dropping resistance in series with said coil.

4. For use with a fabric dryer having a rotatable drum to receive fabrics to be dried, means for blowing a stream of drying air through the drum, and means including a gas fueled burner, for heating the stream of air; a gas flow control arrangement comprising:

(b) one of said valves being a normally closed sole- 8. noid valve and including a coil for opening the valve when connected to a source of electric energy;

(0) the other of said valves being a normally closed bimetal valve and including heating means for causing the valve to open when connected to a source of electric energy;

(d) a circuit including means for simultaneously connecting and disconnecting said coil and said heating means to and from a suitable source of electric energy; and

(c) said bimetal valve being constructed to have a fast opening time compared to its closing time.

5. For use with a fabric dryer having a rotable drum to receive fabrics to be dried, means for blowing a stream of drying air through the drum, and means, including a gas fueled burner, for heating the stream of air; a gas flow control arrangement comprising:

(e) the invention as set forth in claim 4 wherein said coil and said heating means are connected in parallel in said circuit; and

(f) said circuit also including for connecting a dropping resistance in series with said coil after said one valve is open to reduce the voltage applied thereto to valve still sufiicient to maintain it open.

6. The invention as set forth in claim 5 wherein said control includes sensing means, responsive to a flame at the burner, to effectively connect said dropping resistance in series with said coil.

References Cited UNITED STATES PATENTS 2,526,069 10/1950 Douglas 137-637 3,252,227 5/1966 Fleer 26333 3,338,228 8/1967 Walker 431-71 EDWARD G. FAVORS, Primary Examiner US. Cl. X.R. l37-637