GB1560269A - Control device for a waste gas baffle - Google Patents

Description

(54) CONTROL DEVICE FOR A WASTE GAS BAFFLE (71) We, JOH. VAILLANT KG, a German company of 5630 Remscheid, Postfach 101020, Berghauser Strasse 40, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to a control device for a waste gas baffle.

It is known to provide in the supply air path of a heat source two valves parallel with respect to the supply air current whose opening cross-section is controlled by the draft itself. Both valves are rigidly connected with each other, an adjustment of the valves with respect to each other is not provided.

It is also known to provide a series connection of two waste gas valves in the waste gas path of a heat source, which are both driven by a separate servomotor. The positions of the individual waste gas valves are independent of each other, however the maximum throughput cross-sections are the same. For operation of the heat source both waste gas valves must be opened, opening of only one waste gas valves must be opened, opening of only one waste gas valve is not sufficient.

It is further known to employ a waste gas valve in which a bimetal strip is incorporated so that when the bimental responds to heat of the heat source in the waste gas line of which the waste gas valve is positioned, first a partial cross section of the waste gas line is released, whereupon finally the waste gas valve assumes the maximum open position.

It is not provided that the waste gas valve operates stably in the partial open position provided by the opening bimetal strip, rather is the immediate transmission to fully open position provided.

According to the present invention we provide a control arrangement, for a wastegas baffle, comprised of two individual waste gas valves pivotable in a waste gas channel by an electric motor, characterized in that maximum opening of both waste gas valves corresponds to a maximum heating load and that of one waste gas valve to a partial heating load said electric motor actuating the waste gas valves via gearing in such a manner that starting from a closed position of both waste gas valves first the waste gas valve that corresponds to the said partial heating load and then the other waste gas valve is opened and that in case of default of a heat requiring signal said waste gas valves are subsequently closed in an opposite sequence of operations.

The technical progress attainable by the invention resides in the increased efficiency of the heat source since only the waste gas cross-section is released which is just required, and in the operational safety provided since the fuel valves are actuated only when the respective valve has not found its open position.

The invention will be more clearly understood from the following description given with reference to the figures of the accompanying drawings, in which: Figure 1 is a schematic of a gas water heater including fuel valves and waste gas baffle; Figure 2 is a cross-section through gearing for operation of the waste gas valves: Figure 3 is a view of, and Figure 4 is a section through the waste gas valves; Figure 5 is a circuit diagram of the electrical control of the valves, and Figure 6 is a detail of the gearing.

In each of the six Figures the same reference numerals designate the same integers and details.

A heat source shown generally at 1 comprising a gas fired water heater for a circulation central heating system or for domestic water heating has a gas burner 2 supplied by a fuel supply line 3 divided into branch lines 4 and 5, in which respectively there is provided a full load solenoid valve 6 and a solenoid valve 7 each of which is adapted to be actuated by a respective solenoid 8, 9. While the full load solenoid valve 6 releases the gas throughput corresponding to the rated output of the heat source 1, the solenoid valve 7 supplies an adjustable partial load gas throughput. Both solenoids 8 and 9 are connectable respectively via power supply lines 10 and 11 to a supply voltage, the earth connections are shown respectively and 12 and 13. The heat source 1 has a heat exchanger 14 over which fuel gases of the gas burner 2 pass.The heat exchanger 14 is supplied via a return flow line 15 with fluid to be heated which is discharged via a supply flow line 16. The interior 17 of the heat source 1 is shielded by a housing 18 from which a waste gas line 19 leads to a stack 20, a flow safety device 21 being arranged between the two. In the area of the waste gas line 19 a waste gas baffle 22 is provided in the form of two concentrically arranged waste gas valves 23 and 24 of which 24 is the greater in diameter and both of which are adjustable by an operating drive 25 via a concentric double shaft 26.

In Figure 2 the operating drive 25 is seen to consist of a drive motor (not shown) and gearing shown generally at 27. The gearing 27 has a housing 28 having a bearing throughput 29 for a motor drive shaft 30.

The motor M (Figure 5) is a reversible electric motor having a connection V for the return flow (left) and a connecting V (Figure 5) for the supply flow (right) and is adapted for a.c. mains power supply. On the shaft 30 a gear wheel 32 is axially movable along a key 31 a helical compression spring 33 presses against the side of said gear wheel 32 and against the internal side 34 of the housing 28. The gear wheel 32 is positioned against a projection 38 of the housing 28 via a cam disc gear 35 comprised of control cam parts 36 and 37, and is supported in the projection via the shaft 30 provided in a recess 39 therein. The shaft 30 is thus axially and radially positionally supported within interior 40 of the gearing 27 and the gear wheel 32 is pressed against the control cam gear 35 under the influence of the spring 33 as far as possible.The manner of the axial position of the gear wheel 32 being dependent only on the position of the control cam parts 36 and 37 relative to each other. The double shaft referred to above is shown generally at 26, it consists of an inner shaft 41 and an outer sleeve 42 rotatable with respect to each other and which are introduced into the interior 40 of the gearing 27 through bearings 43 and 44. The greater waste gas valve 24 is actuated by the outer sleeve 42 and the smaller inner waste gas valve 23 by the inner shaft 41. The sleeve 42 is rigidly connected to a gear wheel 45, the inner shaft 41 to a gear wheel 46. Both gear wheels 45, 46 respectively carry cam discs 47, 48 by which contact switches 49, 50 can be controlled.

Depending on the axial position of the gear wheel 32 the same can mate either with the gear wheel 45 or with the gear wheel 46.

In Figures 3 and 4 the waste gas line 19 is seen to consist of a relatively thin-walled sheet-metal tube to which there is attached the gear housing 28 on the outside by means of brackets 52. The double shaft 26 passes through the walls of the waste gas line 19 and both elements 41, 42 of the double shaft 26 are rigidly connected with the associated valves. The full-power waste gas valve 24 has the full diameter of the waste gas line 19 in closed position, while the partial load waste gas valve 23 only fills an interior space. The full-load valve 24 is of circular shape, the interior of the circular ring being formed by the partial-load waste gas valve 23. The waste gas valve 19 can be provided with a bearing bushing 53 on the side opposite the housing 28.

In Figure 5 the power-supply line 10 referred to above passes to the full-load solenoid valve 6 leads via a connection 55 of a contact piece 57 restorable against the force of a spring 56 and whose base 58 is connected with a line point 59, which, in turn, is connected via a line 60, a contact 61, and a contact piece 62 with a line 106 of a controller supplying full-load signal.

From the switch point 59 a line 63 leads to a coil 64 of a relay which on the opposite side connects to ground via a line 65. A make contact 66 of this relay in its position of rest is connected in a line 67 of the motor 68 for adjustment of the valves, which is connected via a line 69 with the line 65 and thus to ground. From the base 70 of the contact piece 71 of the make contact 66 a line 72 leads to a contact 73 of the contact switch 49 whose contact piece 74 is adapted to be actuated by a cam 76 of the cam disc 47 against the restoring force of a spring 75. A base of the contact piece 74 is connected with an output of a controller for partial-load operation via a line 77. A line 78 is connected to a controller output 105 and is connected to the lines 65 and 69 connecting to ground via a relay coil 79 and a line 80 leads off from the line 77. Not only the contact piece 62, but also contact pieces 81 and 82 are connected with the relay coil 79. The contact piece 81 connects with the relay coil 79. The contact piece 81 connects the line 78 with a line 83 leading to a base 84 of a contact piece 85 loaded by a compression spring 86 and adapted to be actuated by cams 87 and 88 of the cam disc 48. In a position of rest the contact piece 85 is connected with a line 89 leading to the motor 68 via a switch point 90. In a condition established by one of the cams the contact piece 85 is connected with the line 11. The switch point 90 is connected with a contact 92 of the contact piece 57 via a line 91.Furthermore, the switch point 90 is connected via another line 93 with a base of the contact switch 50 whose contact piece 95 can be removed from a contact 94 of a line 97 against the restoring force of a spring 96 upon actuation by one of the cams 87 or 88, in the path of said line the contact piece 82 of the relay 79 being arranged and connected to the phase R. By a line of action 98 it is elucidated that the motor 68 drives both cam discs 47 and 48.

The cam disc gear 35 (Figures 2 and 6) possesses two control cam portions 36 and 37, one being integral with the housing 28 and the other, with the shaft 30 of the motor (M) 68 (Figure 5). The control cam 100 between the two control cam portions is designed in such a manner that starting from the position of rest 101 in which both waste gas valves assume the closed position, after rotation of the motor shaft 30 through 90" into the position 102 also the partial-load waste gas valve 23 is adjusted by 90 , i.e.

assumes the partial-load open position. When exceeding this 90" position, the control cam portion 36 rises with respect to the control cam portion 37, so that the gear wheel 32 (Figure 2) disengages from the gear wheel 45 and meshes with the teeth of the gear wheel 46. Further follow-up of the motor shaft 30 by 1800 reaches the point 103 the exceeding of which causes the cam disc gear 35 to re-assume its original position, i.e. the gear wheel 32 again leaves the teeth of the gear wheel 45 and meshes with the teeth of the gear wheel 46. The point 104 reached after further rotation through 90" corresponds to the initial position of rest 101.

The modus operandi of the arrangement is as follows:- A position of rest is started with both waste gas valves 23, 24 closed, also the two fuel valves 6, 7 are closed and no voltage is supplied to the controller outputs 105, 106. Now, it is assumed that the controller output 105 is supplied with voltage, since the associated measuring sensor detects a difference between actual value and nominal value. Since the contact 81 is open, voltage is supplied to the coil 79. The relay is energized, whereby the contacts 621 61, 81 and 82 are opened, respectively closed, however, only closure of the contact 81 is decisive since voltage is supplied to the motor 68 via the closed contact 84/85 through the line 89, 69. Consequently, the motor 68 starts a rightward rotation and the shaft 30 is carried along via the gear wheel 32.Also the gear wheel 32 mates with the gear wheel 46 and hence rotates the inner shaft 41. As a consequence thereof the partial-load waste gas valve 23 is caused to assume an open position, when the 90" position is reached the cam 87 removes the contact piece 85 from the line 89 and connects it to the line 11. Therewith the voltage of the controller output 105 connects to the solenoid valve 7/9 via the line 11 so that the valve 7 is opened, fuel is supplied to the burner 2 via the line 3, the valve 7, the line 5 and is ignited. The burner 2 consumes fuel within the scope of a partial-load quantity, and in accordance with the partial load gas quantity also the waste gas path is opened via the waste gas line 19 and the partial-load waste gas valve 23.

Now, if the partial-load heat production is not sufficient, supply voltage is switched to the line 106 from the second controller output. Since the contact piece 62 connects to the contact 61, via the lines 63 and 65 the coil of the respective relay is supplied with voltage, the relay is energized and the contact piece 66 is removed from the line 67. Furthermore, the supply voltage is supplied to the switch point 90 via the switch point 59, the contacts 57/92, so that the motor 68 is again supplied with voltage. The motor 68 starts again rotating rightwardly and now exceeds the 90" position 102. This results in an axial shifting of the gear wheel 32 which now mates with the gear wheel 45.

This means that the partial-load valve 23 remains open. Now, the full-load waste gas valve 24 is adjusted since the gear wheel 45 carries along the outer sleeve 42. After a further rotation about 90" the position according to reference numeral 107 in Figure 6 is reached. In this position the cam 76 of the cam disc 47 opens the contact 57/92, the contact piece 57 being connected to the contact 55 against the action of the spring 56. Thus, supply voltage is supplied to the line 10 signifying that the full-load solenoid valve 6/8 is opened so that the gas burnerreceived the full fuel quantity.

Now if the heat source is again switched to partial-load, the line 106 becomes currentless in default of an output signal from the second controller output 106. This also causes the coil 64 to become currentless so that the contact piece 66 is reswitched to the line 67. This line is now supplied via the line 72 and the now closed contact 49/73 via the line 105.

The contact piece 49 connects to the contact 73 since the cam 76 has meanwhile passed through 90" and controls the contact 57/55. As a consequence thereof the motor 68 starts rotating leftwardly and rotates the cam disc 47 since the gear wheel 32 is still connected with the gear wheel 45 associated to the full-load waste gas valve.

The full-load waste gas valve is re-adjusted through 90" to point 102, in which point the cam 76 lifts the contact piece 49 from the contact 73 and thus interrupts the operation of the motor 68. If a partial-load signal remains on the line 105, the burner 2 continues burning with partial load. The full-load gas supply is interrupted as soon as the cam 76 has left the contact piece 57 since then the line 10 is thus switched to become currentless. This also means that the full-load solenoid valve 8/6 had been closed before the full-load waste gas valve 24 has reached its closed position.

Now if also the signal on line 105 ceases, the coil 79 becomes currentless. Thus the contact 82 closes so that the motor 68 is supplied with voltage via the switch point 90, the line 93, the closed contact 90/96 and the closed contact 82, and restarts rotating rightwardly. If the position according to point 103 is exceeded, the cam 87 leaves the contact piece 85 so that the contact piece 85 will be connected with the line 89 and the line 11 is made currentless. Therewith the sloenoid valve 7/9 is de-energized, the fuel supply to the burner 2 is interrupted and the burner 2 is extinguished. Upon further rotation of the motor 68 also the partialload waste gas valve 24 is closed, and the closing action is terminated in that the cam 87 removes the contact piece 50 from the contact 94 and interrupts any current flow to the motor 68.

In case that from the full-load position of the two waste gas valves neither full-load nor partial-load operation is required, the lines 106 and 105 together become currentless. In such case also the relay coil 79 becomes currentless so that the motor 68 returns both waste gas valves 23, 24 into the position of rest from the position 107 according to Figure 6, since the contacts 82 and 50/96 are closed.

Thus the motor 68 is rotated into the position according to point 104 via lines 97, 93, 90 and 69 until both waste gas valves 23, 24 are closed and the cam 87 removes the contact piece 50 from the contact 96. The boiler is then switched off again so that the line 105 becomes currentless, the inner waste gas valve 23 is in open position and the switch curve in position 102 (see Figure 6).

The motor 68 startsr unning rightwardly since the contacts 82, 95 are closed, opens the large waste gas valve 24, closes the same again and subsequently closes the small valve 23. Starting from position 102 the control curve passes through the positions 107, 103 until finally reaching the end position 104. During this switching operation the return connectaion (leftwardly) of the motor 68 is not actuated, since the only actuating source 105 remains currentless.

WHAT WE CLAIM IS: 1. A control arrangement, for a wastegas baffle, comprised of two individual waste gas valves pivotable in a waste gas channel by an electric motor, characterized in that maximum opening of both waste gas valves corresponds to a maximum heating load and that of one waste gas valve to a partial heating load said electric motor actuating the waste gas valves via gearing in such a manner that starting from a closed position of both waste gas valves first the waste gas valve that corresponds to the said partial heating load and then the other waste gas valve is opened and that in case of default of a heat requiring signal said waste gas valves are subsequently closed in an opposite sequence of operations.

2. The control arrangement as claimed in claim 1 characterized in that the waste gas valves have connected thereto cam discs having electric contact switches for influencing the electir motor as well as the solenoid valves for maximum and partial heating loads.

3. The control arrangement as claimed in the claim 1 or 2, characterized in that the waste gas valves are concentrically arranged one within the other, the outer waste gas valve is supported for maximum heating load, while the inner waste gas valve is supported for partial heating load.

4. The control arrangement as claimed in any one of the claims 1 to 3, characterized in that a drive shaft of the waste gas baffle consists of an inner shaft and an outer sleeve, each connected to an associated gear wheel which is dependent on the position of a cam disc gear are caused to mate with a gear wheel which, in turn is controlled by the drive shaft of the electric motor.

5. The control arrangement as claimed in claim 1 or 4, characterized in that the cam discs are rigidly connected to the associated gear wheel.

6. A control arrangement as claimed in claim 1 constructed and arranged substantially as herein described and as shown in the Figures of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. the cam 76 lifts the contact piece 49 from the contact 73 and thus interrupts the operation of the motor 68. If a partial-load signal remains on the line 105, the burner 2 continues burning with partial load. The full-load gas supply is interrupted as soon as the cam 76 has left the contact piece 57 since then the line 10 is thus switched to become currentless. This also means that the full-load solenoid valve 8/6 had been closed before the full-load waste gas valve 24 has reached its closed position. Now if also the signal on line 105 ceases, the coil 79 becomes currentless. Thus the contact 82 closes so that the motor 68 is supplied with voltage via the switch point 90, the line 93, the closed contact 90/96 and the closed contact 82, and restarts rotating rightwardly. If the position according to point 103 is exceeded, the cam 87 leaves the contact piece 85 so that the contact piece 85 will be connected with the line 89 and the line 11 is made currentless. Therewith the sloenoid valve 7/9 is de-energized, the fuel supply to the burner 2 is interrupted and the burner 2 is extinguished. Upon further rotation of the motor 68 also the partialload waste gas valve 24 is closed, and the closing action is terminated in that the cam 87 removes the contact piece 50 from the contact 94 and interrupts any current flow to the motor 68. In case that from the full-load position of the two waste gas valves neither full-load nor partial-load operation is required, the lines 106 and 105 together become currentless. In such case also the relay coil 79 becomes currentless so that the motor 68 returns both waste gas valves 23, 24 into the position of rest from the position 107 according to Figure 6, since the contacts 82 and 50/96 are closed. Thus the motor 68 is rotated into the position according to point 104 via lines 97, 93, 90 and 69 until both waste gas valves 23, 24 are closed and the cam 87 removes the contact piece 50 from the contact 96. The boiler is then switched off again so that the line 105 becomes currentless, the inner waste gas valve 23 is in open position and the switch curve in position 102 (see Figure 6). The motor 68 startsr unning rightwardly since the contacts 82, 95 are closed, opens the large waste gas valve 24, closes the same again and subsequently closes the small valve 23. Starting from position 102 the control curve passes through the positions 107, 103 until finally reaching the end position 104. During this switching operation the return connectaion (leftwardly) of the motor 68 is not actuated, since the only actuating source 105 remains currentless. WHAT WE CLAIM IS:

1. A control arrangement, for a wastegas baffle, comprised of two individual waste gas valves pivotable in a waste gas channel by an electric motor, characterized in that maximum opening of both waste gas valves corresponds to a maximum heating load and that of one waste gas valve to a partial heating load said electric motor actuating the waste gas valves via gearing in such a manner that starting from a closed position of both waste gas valves first the waste gas valve that corresponds to the said partial heating load and then the other waste gas valve is opened and that in case of default of a heat requiring signal said waste gas valves are subsequently closed in an opposite sequence of operations.

2. The control arrangement as claimed in claim 1 characterized in that the waste gas valves have connected thereto cam discs having electric contact switches for influencing the electir motor as well as the solenoid valves for maximum and partial heating loads.

3. The control arrangement as claimed in the claim 1 or 2, characterized in that the waste gas valves are concentrically arranged one within the other, the outer waste gas valve is supported for maximum heating load, while the inner waste gas valve is supported for partial heating load.

4. The control arrangement as claimed in any one of the claims 1 to 3, characterized in that a drive shaft of the waste gas baffle consists of an inner shaft and an outer sleeve, each connected to an associated gear wheel which is dependent on the position of a cam disc gear are caused to mate with a gear wheel which, in turn is controlled by the drive shaft of the electric motor.

5. The control arrangement as claimed in claim 1 or 4, characterized in that the cam discs are rigidly connected to the associated gear wheel.

6. A control arrangement as claimed in claim 1 constructed and arranged substantially as herein described and as shown in the Figures of the accompanying drawings.