The present invention relates to a device for controlling a dam¬ per regulator at heating boilers, whereby the control device controls the damper regulator to operate a butterfly damper mounted in a flue in order to completely or partially throttle flue exhausts from the heating boiler via the flue after switching off a burner in the hea¬ ting boiler.

There are many systems for operating damper regulators, but they often have a complex structure, requires vast and time-consu- ming measures when installed and are sometimes less suitable for security reasons.

The object of the present invention is to obtain operation of damper regulators by means of a simple, reliable system which meet all safety requirements. This object is arrived at which a device as defined in the following claim 1.

The invention will be further described below with reference to the accompanying drawings. In the drawings, fig. 1 schematically illustrates a device according to the invention for controlling a damper regulatory fig. 2 schematically illustrates a first alterna- tive to the device shown in fig. I fig. 3 schematically illustrates a second alternative; fig. 4 schematically illustrates a valve de¬ vice in connection with the control device; and fig. 5 illustrates a draught sensor comprised in the valve device.

In fig. 1 is schematically shown a heating boiler or heater 1, a flue 2 leading from the heater 1 to a chimney (not shown) and a damper device 3. The damper device 3 is mounted on a mounting plate 4 attached to the flue 2. A spindle 5, which is pivoted in the moun¬ ting plate 4, projects through the plate and carries a damper disc 6, an eccentric disc 7 and an arm 8. The plate 4 covers a hole (not shown) in the flue 2 and the damper disc 6 is located in the flue whereas the eccentric disc 7 and the arm 8 are positioned on the outside of the flue. The damper disc 6 is arranged to be turned be¬ tween a position in which it completely or almost completely closes the flue 2 and a position in which the flue is completely or partly open (such a position is shown in chain-dotted lines) for opening or throttle flue exhausts from the heater 1.

Turning of the damper disc 6 is effected by means of a damper regulator 9. This regulator has a cylinder-piston actuator 10, the cylinder 11 of which is pivoted in a bearing 13 on the mounting plate

4. The piston 12 of the cylinder-piston actuator 10 is pivotally connected to the arm 8 at a joint 14. A tension spring 16 is fitted as a piston retraction spring between the free end of the arm 8 • and a holder 15 on the cylinder 11. A system 32 with incombustible medium 33 is connected to the damper regulator 9 and said system comprises a power aggregate 34 mounted substantially beside and/or beneath the flue 2 for driving the damper regulator via said incombustible medium against the ac¬ tion of a resetting device, e.g. the retraction spring 16. Hereby, the damper regulator 9 itself may be mounted directly onto or adja¬ cent the flue 2, which is advantageous with regard to power trans¬ mission, _, inspection and service, while the power aggregate may be positioned at safe distance from the flue 2, so that the power aggre gate is not damaged by heat and/or may be driven by a combustible medium 31 without leading said medium close to the flue 2.

The power aggregate 34 may be driven in different ways and by different types of medium. In the embodiment illustrated in fig. 1, the power aggregate is driven by a combustible medium 31 including oil from the oil pump 18 of the heater 1. To enable this, the oil- pump 18 is connected to the power aggregate 34 by an oil conduit ^• 38, and the power aggregate is connected to the damper regulator 9 by a conduit 39 with incombustible medium.

In the embodiment of fig. 1 the power aggregate comprises a cylinder-piston actuator 34, the piston 35 of which is designed to be influenced by combustible medium 31 and affect incombustible me¬ dium 33.

If the oil pump 18 of the heater 1 does not permit return flow from the system, a return, conduit system 36 may be provided to con¬ nect, by means of an oil conduit 40, a portion of the system 30 with combustible medium 31 extending between the oil pump 18 and the power aggregate 34, with a system 24 extending from the oil pump 18 to an oil tank 25, whereby the return conduit system 36 comprises a valve device 37 which via an electric circuit 41 is controlled by a thermostat device 21 of the heater 1 to open the return conduit system 36 for resetting the damper regulator 9 but closing said sys¬ tem when the regulator is operated by influencing the system 32 with incombustible medium 33 from the system 30 with combustible medium 31.

The oil pump 18 is driven by an electric motor (not shown^rr T-m= f OKPI

nected to the mains by a feed cable 19. The feed cable 19 is routed through an electric control system 20 of the heater, which includes the thermostat device 21, a relay 22 and preferably a pyrostat 23. These components of the control system 20 determine when the heater 1 is to be started or stopped. The oil pump 18 is connected to a burner head 27 in the heater by an oil delivery pipe 26.

When the heater 1 is started, the piston 12 will be extended so that the arm 8 and by that the damper disc 6 is turned from ^" a closed to an open position. Simultaneously, the burner head 27 will be supplied with oil and put in action. When the oil pump 18 stops, the piston 12 and the damper disc 6 will be turned back to their closing position by the retracting spring 16.

The device according to fig. 1 may be used at other heaters than oil-fired heaters, e.g. gas-fired heaters, whereby the system 30 contains gas. The system 32 preferably contains incombustible liquid with lubricating properties, e.g. water mixed with incom¬ bustible cooling oil in the proportions 50 : 50.

In fig. 2 is schematically shown a heater 1 or heating boiler with a gas burner 42 fed by a gas conduit 43. The gas supply to the burner 42 is controlled by a valve device 44 which in turn is quided by an electric system 45. Said electric system comprises a security device 46, a thermostat device 47 and other arrangements 48 requi¬ red for controlling the operation of the heater, whereby the system 45 is connected to the mains by contact means 49. To the cylindrical space 50 of the damper regulator 9 on one side of the piston 51 is a power aggregate 64 (in this case a water pump unit) connected via a pressurized water system 52, which pre¬ ferably comprises a system for delivering water to a water heater 54 in the heater 1. The pressurized water system 52 includes a water conduit 55 which is connected to a pressure side 53 of the system on one hand, and another water conduit 56 connected to the damper regulator 9 and to an outlet 58 by a water conduit 57 on the other hand. Before the branch 59 between the water conduits 55, 56, 57, the conduit 55 is provided with a magnetic valve 60, and after the branch the water conduit 57 is provided with another magnetic valve 61. The magnetic valves 60, 61 are electrically controlled from the thermostat device 46 of the heater 1 via lines 62 and 63.

When the burner 42 of the heater 1 is started, the thermostat device 46 controls the magnetic valve 60 to open the water conduit

55 while at the same time the magnetic valve 61 is controlled to close the water conduit 57. Hereby, the power aggregate 64 will b connected to and generate in the conduit 56 and the cylinder spac 50 a pressure such that the piston 51 is displaced against the ac tion of the retracting spring 16. This means that the damper disc 6 is turned until it has reached the position indicated with chai dotted lines, whereby the flue 2 is substantially open to release flue gases from the heater 1.

When the burner 42 is stopped, the thermostat device 46 cont rols the magnetic valve 60 to close the conduit 55 while the magn tic valve 61 is controlled to open the conduit 57. Hereby, water may flow from the cylinder space 50 via the water conduit 57 and via the water conduit 56 to the outlet 58 (e.g. a draining gutter which means that the pressure in the cylindrical space 50 may dro so that the retracting spring 16 can return the piston 51. This r turn movement of the piston 51 means that the damper disc 6 is tu ned back to the position closing the flue 2 completely or almost completely, whereby hot flue gases are prevented from being relea sed when the burner 42 has stopped. In the embodiment according to fig. 3, the retracting spring 16 has been replaced by a return-water conduit system 65 comprisi a water conduit 66 connected to the pressurized water system 53 a connected to a water conduit 67 to a cylindrical space 68 on the other side of the piston 51 and to an outlet conduit 69 leading t an outlet 70. In the water conduit 66 there is mounted a magnetic valve 71 and another magnetic valve 72 is provided in the water c cuit 69, said magnetic valves being electrically controlled by th thermostat device 46 via lines 73 and 74.

In order to retract the piston 51, the magnetic valve 71 is controlled by the thermostat device 46 to open the water conduit

66 when the burner stops. Hereby, the power aggregate 64 will com nicate, via the pressurized water system 53, with the space 67. w means that the pressure therein increases and the piston 51 is mo in the return direction, which is possible while the magnetic val 61 opens the water conduit 57 fox discharge of water from the wat conduit 56. When the water conduit system 52 again is controlled open the damper disc 6, the thermostat device 46 controls the mag tic valve 72 to open the water conduit 69 to the outlet 70 so tha water may flow out of the water conduit 67, whereby the pressure

the space 67 decreases for forward movement of the piston 51.

The embodiments of fig. 2 and 3 are suitable for oil-fired heaters. The damper regulator may be of an entirely different type than the regulator shown and the pressurized water system need not lead to a water heater but may be a pressurized water system for another purpose. It may also be noted that the present water con¬ duit system 52 (and eventually 65) may comprise manually adjustable valves 75 (and eventually 76) for controlling the through-flow capacity of the systems or for closing thereof, which may be an advantage during service and/or if the damper disc must be turned temporarily for sweeping of the flue 2.

The heater 1 illustrated in fig. 4 has an oil pump 18 which by an oil delivery pipe 24a and an oil return pipe 24b is connec¬ ted to an oil tank 25. The burner device 77 of the heater 1 co - prises the oil pump 18 and a relay 77a and the heater comprises the thermostat device 21.

The damper disc 6 is mounted in the flue 2 and operated by the oil pump 18 via a conduit system 78 and a control system 79. The conduit system 78 comprises an oil supply line 80 connecting the oil pump 18 to an oil space 81 in a power aggregate 82 forming part of the control system 79. The conduit system 78 also comprises an oil return pipe 83 connecting the oil space 81 with the pipe 24b between the pump 18 and the tank 25.

The power aggregate 82 of the control system 79 is mounted at substantial distance from the flue 2 and comprises a piston 84, separating the oil space 81 from another space 85 containing an in¬ combustible medium, e.g. glycol. The space 85 is by a conduit 86 connected to a damper regulator 9 (schematically shown), the piston 82 of which is adapted to be affected by the oil pressure in the conduit system 78 via the conduit 86 of the control system 79 for turning the damper disc 6 when the pressure in the control system 79 increases, but be retracted for turning the damper disc 6 back by means of a retracting spring 88 when the pressure in the con¬ trol system 79 decreases. The flow of oil in the conduit system 78 is controlled by means of a valve device 89 which in turn is controlled by an elect¬ ronics unit 90 (this and other electric units are shown in chain- dotted lines) under the influence of a draught sensor 91 sensing variations in the draught through the heater 1 relative to a preset

value.

The conduit system 78 comprises three magnetic valves 92, 93 and 94, of which the valve 92 is used for controlling the flow in the conduit 80, the valve 93 in a return branch 83a of the return pipe 83 and the valve 94 in a return branch 83b of the return pipe. The magnetic valve 92 preferably closes the oil supply line 80 when said valve is in a dead condition, the valve 93 preferably closes the return branch 83a when said valve is in a dead condition but the valve 94 preferably opens the return branch 83b when said valve is in its dead condition.

The device functions such that when the burner 77 and oil pump 18 start, the magnetic valve 92 is controlled to open the oil supply line 80 while the valve 94 closes the return branch 83b and the re¬ turn pipe 83 is completely closed since the valve 93 is controlled to close the return branch 83a. The oil pump 18 increases the pres¬ sure in the oil space 81, whereby the piston 84 is moved, and the piston 82 is displaced by means of medium in the conduit system 78 so that the damper disc 6 is turned to open position. The damber disc 6 is completely open during a certain air period (5 - 30 se- conds), whereafter the burner starts and the heating period is ini¬ tiated. The magnetic valve 92 is thereafter controlled to close the oil supply line 80 and after a certain period of time, e.g. 20 se¬ conds, the draught through the heater.1 is registered by the sensor 91 and the magnetic valve 93 is controlled to open the return branch 83a as long as the pressure in the oil space 81 drops at such a rate that the damper disc 6 returns from a completely open position to a position corresponding to the draught selected as suitable for the present device by presetting the draught sensor 91. The draught sensor continuously indicates variations in the draught through the heater relative to the preset value and continuously controls the valve device 89 to open or close the pipes and lines of the conduit system 78 so that the damper disc 6 immediately reacts for reset¬ ting the draught through the heater to the preset value.

When the temperature in the heater has reached a preset value, the thermostat 21 cuts the current to a magnetic valve (not shown) on the burner and to the magnetic valves 92 -94 in the valve device 89, which means that the valves 92 and 93 closes the conduits 80 and 83a while the valve 94 opens the conduit 83b such that oil via said conduit 83b and the return pipe 83 may flow to the return pipe

24b, whereby the pressure in the oil space decreases and the damper disc 6 is closed by the spring 88.

The draught sensor 91 comprises a membrane chamber 95 separa¬ ted into two chamber portions 96 and 97 by a membrane 98. The cham- ber portion 96 communicates with the interior of the heater 1 via an opening 99, whereby variations in draught in the heater are propagated to the chamber portion 96. These draught variations in the heater 1 affects the membrane 98 which curves in one or the opposite direction and these deflections are transferred by an arm 100 with a contact plate 101 movable between contacts 102 and 103. These contacts are mounted on a sleeve 104 with a pointer 105, said sleeve being screwed into a set screw 106 for moving the sleeve in one or the opposite direction for presetting the desired draught. The draught sensor 91 generates a signal that the damper disc 6 shall be turned in one direction when a circuit (not shown) is clo¬ sed by the contact plate 101 engaging the contact 102, but generates a signal to turn the damper disc 6 in the opposite direction when another circuit (not shown) is ^' closed by the plate 101 engaging the contact 103, so that the degree of through flow in the flue 2 is continuously adjusted for maintaining the preset draught.

The illustrated device also comprises a limit switch 107, a pressure switch 108 and other components for the operation of the heater 1. The construction and function thereof are previously known and are therefore not further described. The heater 1 of fig. 4 may also comprise a gas-operated burner instead of an oil-operated. In that case, the conduit 80 is connec¬ ted to a water conduit system (not shown) instead of using the pres¬ sure therein. The return pipe 83 leads to an outlet device (not shown) for discharging water from the space 81, which thus is a space for water, not oil.

The invention is not limited to the embodiments shown in the drawings and described, but may vary within the scope of the fol¬ lowing claims. Thus, the valve device 89 may include a different number of magnetic valves or other types of valves.