US3810249A

US3810249A - Gas/electric control mechanism

Info

Publication number: US3810249A
Application number: US00226046A
Authority: US
Inventors: Gowan E Mc
Original assignee: United Gas Industries Ltd
Current assignee: United Gas Industries Ltd
Priority date: 1971-03-05
Filing date: 1972-02-14
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: JPS5036902B1; DE2206854A1; GB1375550A

Abstract

A control mechanism particularly for use with an absorption-type refrigerator of the kind which has provision for heating powered both by gas and by electricity, either of which may be used to the exclusion of the other. The control mechanism operates both an electrical switch for the electricity power and a gas valve for the gas supply by a common mechanical linkage under the influence of a temperature sensor, so that whichever heating method is selected the control mechanism needs no adjustment.

Description

United States 1 Patent 2 [191 2,228,343 I 1/1941 COOiiS 236 99 BX McGowan May 7, 1974 Q [54] GAS/ELECTRIC CONTROL MECHANISM 2,463,712 3/1949 Newell 236/15 A X 3,295,334 l/l967 Hult [75] inventor: Em MCGWM shepperton, 3,284,610 11/1966 01011 g I land 3,105,363 l0/l963 V011 Der Sher 62/148 [73] Assignee: United Gas Industries Limited,

London England Primary Examiner-C. L. Albritton [22] Filed; 1 72 Attorney, Agent, or Firm-Roberts B. Larson et al.

[211' App]. No.: 226,046

v v [57] ABSTRACT 30 F A heat P 1': D m 1 1 M g f; Z y a 6085 A control mechanism particularly for use with an abmam l 71 sorption-type refrigerator of the kind which has provision for heating powered both by gas and by electric- -1 219/279 ity, either of which may be used to the exclusion of [58] Fieid 23 the other. The control mechanism operates both an T' B 337/3O6 electrical switch for the electricity power and a gas valve for'the gas supply by a common mechanical linkage under the influence of a temperature sensor, [56] Ref 1 C1 so that whichever heating method is selected the con- UNITED .gg zsgs lLZTENTS- I trol mechanism needs no adjustment.

8 Claims, 2 Drawing Figures I f 29 bi5gz b/49 33+ o 11 43 44 12 )K I6. 32 l5 /4/ r 7i 22- S 55 14 k 34/ 20 w/ i\ 40 PATENTEDMAY H974 I I 3.810.249-

GAS/ELECTRIC CONTROL MECHANISM This invention relates to a control mechanism arranged to operate both a gas valve and an electrical switch.

mechanical linkage operating both said gas valve and said electrical switch in response to movement of said movable means.

Preferably said mechanical linkage includes range adjusting means, whereby the sensed range of temperatures at which said valve and switch are operated may be adjusted.

Said range adjusting means may include a spring arranged to oppose operating movement of said linkage, and cam-operated means for adjusting the tension ofv said spring. Said cam of said cam-operated means may be manually operated by manual means whereby to set a desired range of temperatures. The mechanical linkage may include a snap'action device operating either on said electrical switch only or on said switch and said gas valve.

A preferred'use for the control mechanism is in an absorption type refrigerator having both an electrical heater and-a gas burner either of which may beused to the exclusion of the other. The gas valve may include a flame proving device operative to prevent gas being supplied to the burner when a flame is not present. The control mechanism in this case includes a reset ability whereby the flame proving device is overridden during initial ignition of the burner. The reset ability may be provided by a push button, which may be concentric with the manual means for rotating the range adjusting cam. I

The gas valve preferably comprises a valve member movable off a seat by a push rod which is contacted by said mechanical linkage. Said electrical switch preferably comprises a pair of contacts, one of which is movable by a push rod which is contacted by said snapaction device. j I

Specific embodiments of the invention are shown in the accompanying drawings, in which: 7

FIG. 1 is a schematic sectionthrough one form of combined control mechanism, and

FIG. 2 is a view of a modification of part of the control mechanism of FIG. 1.

Referring first to FIG. 1, the combined control mechanism is intended for use with an absorption type refrigerator. Such refrigerators operate on a cycle including a heating process which may be powered using either electrical resistance heaters or gas burners as the source of heat. The combined control shown will control the heating unit whichever form of heat source is connected without any need for internal alterations.

The control has-a gas valve 11 controlling the flow of gas from an inlet 12 to an outlet 13 which supplies the said gas burners. The valve 11 is mounted on a rod 14 which passes through ,a flexible gas-tight seal 15 into a gas-free chamber 16.

A thermal assembly, part of which is shown at 18, is of the capillary type with a temperature sensing bulb (not shown) positioned in the refrigerator or in the refrigerating fluid to sense the temperature thereof. The

fluidwhich fills the capillary tube causes a bellows l9 to expand or contract according to the sensed temperature, this moving an abutment 20 up as the temperature ture at 23 and has one arm thereof in contact with the abutment 20 so that it is pivoted about point 23 as the sensed temperature changes. The other arm thereof abuts the rod l4 of the valve 11. As the temperature rises therefore the rod 14 is continuously moved to the right as seen in FIG. 1. The valve is thereby moved off its seat allowing more gas to enter the burners. The amount of gas flowing is therefore increased as the temperature rises so as to increase the refrigerating effect and to tend to reduce the temperature. As the tempera ture drops in response to the increased refrigerating effect the rod 14 moves to the left, so gradually closing the valve. The sensed temperature is thereby kept within a predetermined range.

The control also has anelectrical control switch 25 connected to control the electrical supply to the electrical resistance heater. One of the contacts of the switch is mounted on a spring arm, which is contacted by a push rod 26 which extends into the chamber 16. L-shaped lever 22 carries an extension 28 to which is attached one end of a U-shaped snap action leaf spring 29. The other end of the spring 29 is attached to a pivoted member 30 adjacent the push rod 26. As the sensed temperature rises the lever 22 moves, carrying with it the extension 28. Theinitial movement is taken up'by flexing of the spring 29, so that pivotal member 30 is not moved. At a predetermined temperature, however, the extension 28 has moved to an overcentre position with respect to the spring 29 which therefore snaps over, moving the pivoted member rapidly to the left, to the position shown on FIG. 1. In this movement the pivoted member 30 is separated from the push rod 26 and the spring arm closes the contacts of switch 25, which has the effect of starting the refrigerating effect. When this has effected a drop in the sensed temperature, the spring 29 snaps back into its original position, urging member 30 to the right and causing the contacts to open. Pivotal member 30 has its movement limited by stops, for example formed by an opening in an outer casing as shown. In the closed position of the switch contacts, the pivotable arm 30 does not contact push rod 26. This is because during the action of the spring 29 there is a short period of uncertainty when the spring may dither and it is important that this dither should not be imparted to the contacts. When the contacts are open, however, the dither is not important, since it is not sufficient to cause the contacts to close prematurely.

It will therefore be seen that the single thermal assembly l8 and single lever 22 operate equally the gas valve 11 and the electrical switch 25. If the refrigerator is connected to a gas supply the electrical switch will be left disconnected and will therefore open and close ineffectively, while gas valve 11 is operating the refrigerator. On the other hand, if the refrigerator isconnecte'd to an electricity supply, valve 1 1' will open and close ineffectively while the electrical switch 25 effects the operation of the refrigerator. No adjustment is therefore needed to the refrigerator controls to effect changeover from a gas to an electricity supply.

The lever 22 is pivotally urged into contact with the abutment 20 by a coil spring 32 which extends between one of the arms of lever 22 and a further lever 33 pivoted at 34 to stationary structure. The free end .of lever 33 extends into contact with a rotatable cam 35 which is secured vto a rotatable range spindle 36 which extends through the outer casing of the chamber 16. A temperature index surrounds the range spindle 36, so that spindle 36 may be manually rotated to select a desired operating temperature range for the refrigerator. Rotation of the spindle rotates cam 35 which in turn pivots lever 33 to adjust the biassing tension on spring 32 and thereby the resistance to motion of lever 22 and the temperature range over which the electric switch 25 and gas valve 11 open and close. It will be noted that the single range spindle adjusts both gas valve and electric switch operation together.

Associated with the gas valve 11 is an electromagnetic flame proving valve 40. A thermocouple (not shown) is positioned adjacent the gas burners to sense the temperature rise thereof. The electrical signal from the thermocouple operates a solenoid 41 which attracts an armature 42. Secured to armature 42 is a valve plate 43 positioned adjacent a vlave seat in series with the valve 11. A coil spring 44 tends to urge the plate 43 towards the seat so as to hold the valve closed. When the presence of a flame is sensed by the thermocouple,

the solenoid is energised and the armature and valve ber 16 is pivoted at 52to stationary structure and has one arm thereof abutting both push

rods

47 and 50.

The other arm of lever 51 abuts a reset shaft 53 which extends centrally through the range spindle 36 and out from the other side thereof. A spring 54 operates between a knob fixed to the outer end of the reset shaft and the range sprindle 36 to urge the reset shaft upwardly as seeninFIG. 1. When the refrigerator is being gas-operated, for starting purposes the knob is manually depressed against this spring pressure, the one arm of lever 51 operates to open the pilot burner valve 46 and to operate the ignition switch 49. The said one arm of lever 51 also co-operates with a collar 56 on the rod I 14 to push the rod to the right to open the gas valve 11.

An extension of rod 14 engages valve 43 to push this 'valve open also, but this extension is not long enough to open the valve 43 in normal operation of valve 11 under the control of lever 22. The pilot burner is thereby lighted, and in turn ignites the main burners.

' The reset knob is held down for a few seconds to allow the burners to generate sufficient heat to operate the thermocouple and thereby to hold open the flame proving valves 40, 43. The reset knob is then released, the ignition switch is opened and the pilot valve 46 closes. The refrigerator then operates under the control of the thermal assembly 18 and the main gas valve 11. The attraction of solenoid 41 for armature 42 is not sufficient to pull the armature from the closed position, but can only hold it in the open position once it has been placed in that position by the manual operation of lever 51.

When the refrigerator is being electrically operated there is no need to depress the knob, but if by chancethis should be done, no damage is done because no gas is present.

It will be noted that in the above described embodiment the gas valve has a modulating action (i.e., it takes up positions intermediate the open and closed positions according to the sensed temperature) while the electrical switch 25 is snap action. In some types of refrigerator it is desirable that the gas valve should also be snap action (i.e., it should alternate between fully open and standby positions). FIG. 2 shows the modification to the structure of FIG. 1 necessary to effect this. Lever 22 and extension 28 operate a snap action spring 29 as in the previous embodiment. The pivoted member 30 of FIG. 1 is however replaced by a longer lever 30 which operates the push rod 26 of switch 25 in the same manner as described in relation to FIG. 1. However the lower extremity of member 30 now abuts the rod 14 to operate the gas valve 11. Accordingly the gas valve 11 is operated with a snap action at the same times as the electrical switch 25.

In one variation of the above-described embodiments, the range spindle 36 and reset shaft 53 are not concentric but are positioned side-by-side. Another variation has a flame proving valve of the mercury vapour type.

I claim:

1. A control mechanism comprising a mechanical linkage, a temperature-sensitive device which is positioned to operate said mechanical linkage, a gas-valveoperating member located to be operated by said mechanical linkage, a manually-operable lever also located to operate said gas-valve-operating member, a pilot-valve-operating member located to be operated by said manually-operable lever, an electrical-ignition operating member located to be operated by said manually-operable lever and an electric-switchoperating member located to be operated by said mechanical linkage.

2. A control mechanism as claimed in claim 1, wherein said mechanical linkage includes an L-shaped pivoted lever having one arm contacting said temperature-sensitive device and another arm contacting said gas-valve-operating member.

3. A control mechanism as claimed in claim 1, wherein said mechanical linkage includes a snap-action spring means which contacts said electric-switchoperating member.

4. A control mechanism as claimed in claim 1, including a spring means operatively connected to said mechanical linkage to oppose operation thereof by said temperature-sensitive device, tension-adjusting means operating on said spring means, and a spring resistance located to oppose manual operation of said manuallyoperable lever.

5. A control mechanism as claimed in claim 4, including a manual rotatable member operating said tension-adjusting means, and a manual push button operating said manually-operable lever, said rotatable memher and said button being concentrically arranged on the exterior of the control mechanism.

6. A control mechanism as claimed in claim 5, wherein said manual rotatable member is operatively connected to rotate a cam means comprising said tension-adjusting means.

7. A control mechanism as claimed in claim 3, wherein said gas-valve-operating member is also operated by said snap-action spring.

8. A control mechanism as claimed in claim 7, wherein said gas-valve-operating member and said electric-switch-operating member each comprise respective push rods both located to be contacted by a pivoted lever operated by said snap-action spring, said pivoted lever forming part of the mechanical linkage.

Claims

1. A control mechanism comprising a mechanical linkage, a temperature-sensitive device which is positioned to operate said mechanical linkage, a gas-valve-operating member located to be operated by said mechanical linkage, a manually-operable lever also located to operate said gas-valve-operating member, a pilotvalve-operating member located to be operated by said manuallyoperable lever, an electrical-ignition operating member located to be operated by said manually-operable lever and an electricswitch-operating member located to be operated by said mechanical linkage.

3. A control mechanism as claimed in claim 1, wherein said mechanical linkage includes a snap-action spring means which contacts said electric-switch-operating member.

4. A control mechanism as claimed in claim 1, including a spring means operatively connected to said mechanical linkage to oppose operation thereof by said temperature-sensitive device, tension-adjusting means operating on said spring means, and a spring resistance located to oppose manual operation of said manually-operable lever.

5. A control mechanism as claimed in claim 4, including a manual rotatable member operating said tension-adjusting means, and a manual push button operating said manually-operable lever, said rotatable member and said button being concentrically arranged on the exterior of the control mechanism.