Patent GB-379408-A (GB)
Title: Improvements in or relating to steam heating systems
IPC: F24D1/00
Filed: 1931-06-05
Abstract: 379,408. Electrically-actuated valves. JACKSON, L. MELLERSH-, 28, Southampton Buildings, London.-(Webster Tallmadge & Co., Inc. ; 50, Church Street, New York, U.S.A.) June 5, 1931, No. 16525. [Class 135.] A steam heating system preferably divided into a plurality of heating zones, comprises a distributing pipe system for each zone, a number of radiators preferably provided with an inlet orifice proportionate to the radiating surface' and offering a high resistance to the flow of steam relative to the resistance of the distributing pipe system, preferably, local thermostats to control the opening of the individual inlet orifices, and control means for each distributing pipe system which are adjustable for different percentages of the maximum steam supply to be admitted and are responsive to variations in the steam pressure to maintain the supply at the required adjustment. The adjustment of the control means may be manual but is preferably responsive to outside temperature and air pressure variations. The control means preferably operates to maintain the steam supply under pressure variations by effecting large changes in the amount of steam admitted on variation at a relatively low pressure and gradually decreasing changes as the initial pressure increases. The control means F is shown in Figs. 6, 7 and 8. The valve controlling the supply to a distributing pipe system is operated by an electric motor 7 through a train of gears 11, 12, 14, 15, the gear 15 being connected to the valve stem 32 by a spring clutch shown in detail in Fig. 9. The yoke 23 is connected to the valve by pins 29 sliding in openings 30 in a yoke 31 fixed to the valve stem 32. The angular movement of the clutch is limited in one direction by the springs 26 and in the opposite direction by a stop-pin 27 on the yoke 23 coacting with a shoulder 28 on the yoke 21. The direction of rotation of the motor 7 is controlled by a switch, Fig. 11, having two fixed contacts 33, 34 and a movable switch blade 35. The movement of the blade 35 is controlled by the steam pressure which acts on a diaphragm 37. This diaphragm is held by a spring 43 against the short arm of a bell-crank lever 40 pivoted in a block 41 secured to the outer casing. The long arm of the lever 40 acts through a link 47 on a pressure lever 48 secured to the rear end of shaft 49, Fig. 7, the levers being so related that with low steam pressure the bell crank acts on the'link 47 at a right-angle, which angle gradually approaches 180‹ as the bell crank is rocked further by increasing steam pressure, thus effecting a gradually decreasing throw of the pressure lever 48. The shaft 49 passes through the hub of a ratchet gear 50 having on its outer face a crown arcuate cam 51 with inclined end 51a rotating thereon, and fixed to its outer end is a roller block 52 carrying a lever 54. This lever has a roller 55 at its outer end riding on the cam 51 and at its inner end bears against a push-pin 56 reciprocating axially within the shaft 49. The rotation of the shaft 49 by the pressure lever 48 reciprocates the pin 56 through the cam 51 and lever 54 and this pin moves the switch blade 35 against the pull of the spring 58 which tends to hold it against the contact 34. The spring 43 is adjusted so that the diaphragm is in a neutral position with no steam pressure and is further adjusted to the desired steam pressures by the nut 44, and the opposing forces exerted by the pin 56 and the spring 58 are correlated so that when the roller 55 is halfway up the inclinedface 51a of the cam, the blade 35 is midway between the contacts 33, 34. When the control valve is fully closed or fully open, the motor is automatically stopped by the blade 35 being moved from the appropriate contact by a rocking arm 72 carrying pins 74, 74a which then engage the blade 35. This arm is actuated by a lever 68 which in turn is rocked by tappets 66, 66a set in a gear 64 which is rotated through a pinion 63 by the valve stem 32. The ratchet gear 50 is rotated to adjust the angular position of the cam thereon by means of a double relay with electromagnets 78, 78a. The armature 80 actuates the pawls 83, 83a, and is normally held so that these are out of engagement by stirrups 84, 84a connected by a spring 85. Each time one of the magnets is energized, the armature engages one of the pawls and moves the gear 50 one tooth in the appropriate direction, stops preventing movement of more than one tooth at a time. The gear 50 is held when stationary by a click-brake 89. This operation can be performed manually by operating a twoway switch or by auxiliary control means which is responsive to the conditions prevailing outside the building. This auxiliary control means G consists of a diaphragm 109 and a thermostat 103, Fig. 13, set in an opening 101 in the outside wall of the building. The movement of the diaphragm is transmitted through a lever 112, pivoted at its lower end, and a spider lever with arms 114, 117, held under tension by a spring 120, to a stiff upright wire 106a sliding in the tube 107a. The nut 118 is adjusted to give the steam flow required in the particular installation and the levers are so proportioned that variations in pressure with light wind pressure effect relatively large movements of the wire and progressively smaller movements as the wind pressure increases. Similarly the movement of the thermostat 103 actuates the upright wire 106 sliding in tube 107. To the two tubes 107, 107a is attached a floating switch blade 123 which passes at its centre through a wide transverse slot in a movable insulating block 124. The blade 123 is allowed to move vertically and rock slightly in the slot by pins 125, 125a. Two switch contacts 126, 126a are adjustably set in the block above and below the blade 123. The block 124 is attached to a vertically sliding rod 127 carrying at its upper end a rack bar 129, held in position by pins 130 and spring clicks 131. The rack bar is reciprocated vertically by a double relay similar to that described in connection with the main control gear. The effect of an increase in outside temperature or a decrease in wind pressure is to move the blade 123 against the upper contact 126, the circuit being closed through the coils of the. magnet A78 of the auxiliary control and the magnet 78a of the main control device F. The latter relay acts to move the ratchet gear 50 and cam 51 one tooth in a clockwise direction to start the motor in the direction to close the steam valve, and the former relay acts to raise the block 124 one tooth in an upward direction. If the outside variations are sufficiently great, the cycle is continued until the supply of steam is shut off sufficiently. The automatic control T for each radiator according to local conditions is shown in Fig. 20. The supply of steam is controlled by a throttling head 137 in the steam inlet pipe 135 of the radiator. This valve is operated by an electromagnet 141, the circuit of which is controlled by a local thermostat 142, By suitable adjustment of the screw 139 and of the maximum and minimum temperature to which the thermostat will respond, the device maintains the steam flow to the radiator close to the mean quantity required.