US3522661A

US3522661A - Pneumatic control system and method

Info

Publication number: US3522661A
Application number: US717586A
Authority: US
Inventors: Douglas R Scott
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1968-04-01
Filing date: 1968-04-01
Publication date: 1970-08-04
Anticipated expiration: 1987-08-04
Also published as: NL6904932A; DE1916527A1; BR6907691D0; BE730778A; FR2005293A1; GB1269084A

Description

1970 D. R. SCOTT 3,522,661

PNEUMATIC CONTROL SYSTEM AND METHOD Fild April 1, 1968 2 Shets-Shed 1 All 83 I07 I R I a4 us 82 as u? us Ii 12. Q

"5 I0 7-3 n2 I lo N 3 J8! as so 23 22 24 25- 7 w 2 lol 28 2? 7s 75 FIG 79 56 INVE/VTU/P I03 DOUGLAS R. SCOTT 74 BY 72 FIG. 3 M0 {M ATTORNEYS Aug. 4, 1970 D. R. SCOTT PNEUMATIC CONTROL SYSTEM AND METHOD 2 Sheets-Sheet 2 Filed April 1, 1968 I I07 345 I338 (I36 I28 L 5 m 4 x w dun I H A H l r l o [I25 M O B //V I/E/I/TOR DOUGLAS R. SCOTT by W ,J' M

ATTORA/E Y5 United States Patent Office 3,522,661 Patented Aug. 4, 1970 3,522,661 PNEUMATIC CONTROL SYSTEM AND METHOD Douglas R. Scott, Elkhart, Ind, assignor to Rohertshaw Controls Company, Richmond, Va., a corporation of Delaware Filed Apr. 1, 1968, Set. No. 717,586 Int. Cl. F261; 21 06' US. C]. 34-46 35 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a pneumatic control system for a clothes dryer wherein the flow of fuel to the main burner means is pneumatically controlled in such a mannor that the ignition means for the main burner means must be first pneumatically actuated before the pneumatic control system will pneumatically open the fuel supply means to the main burner means, the control system including pneumatically operated logic units to assure that the ignition means is always pneumatically operated before the main burner means can be pneumatically operated to its on condition each time there is a requirement to turn on the main burner means.

This invention relates to a pneumatic control system for a fuel burning apparatus as well as to an improved method of operating such a control system and to improved parts for such a control system or the like.

It is well known that a fuel burning apparatus, such as a clothes dryer or the like, has been provided wherein the flow of fuel to the main burner means thereof is controlled by an electric thermostat means that will not permit the flow of fuel to the main burner means until after an electrical ignition means has been electrically actuated so as to assure that the flow of fuel to the main burner means will be ignited.

However, no such control means have been provided for a pneumatically operated burner means.

Accordingly, one of the features of this invention is to provide a pneumatic control system for controlling the flow of fuel to a main burner means of an apparatus or the like in such a manner that the ignition means for the main burner means must first be pneumatically actuated each time before the control system will permit a how of fuel to the main burner means.

Another feature of this invention is to provide such a pneumatic control system and if the main burner means should not be properly ignited by such actuated ignition means after a predetermined number of ignition attempts, the control system will completely terminate the operation of the main burner means until manually reset.

In particular, the embodiment of this invention provides a pneumatically operated logic memory unit which is utilized in combination with a pneumatically operated logic not unit so that the same must each receive particular pneumatic signals from the pneumatically operated ignition means before the same can effectively direct their output signals to a pneumatically operated logic and unit which will pneumatically control the main burner means, the pneumatically operated logic not unit only causing the pneumatically operated logic and unit to interconnect a fuel source to the main burner means if the pneumatically operated ignition means has been first pneumatically actuated as will be apparent hereinafter.

In addition, the pneumatic control system of this invention provides a pneumatically operated safety interlock so that if after a predetermined number of recycling starting attempts for the control system have been provided without an operation thereof, the pneumatically operated safety interlock means will shut down the entire system and the same cannot be activated again until the pnuematically operated safely interlock means is manually reset as will be apparent hereinafter.

Accordingly, it is an object of this invention to provide an improved pneumatic control system for a fuel burning apparatus or the like, the system of this invention having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved method of operating a control system for a fuel burning apparatus or the like, the method of this invention having one or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide improved parts for such a control system or the like.

Other objects, uses of advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIG. 1 is a schematic view illustrating the improved control system and method of this invention.

FIG. 2 is an enlarged, fragmentary view of the pneumatically operated logic units of the control system of FIG. 1 with the logic units being illustrated in cross section.

FIG. 3 is a schematic view illustrating the signal path in the logic system utilized in the control system of FIG. 1.

While the various features of this invention are hereinafter described and illustrated as being particularly adapted to pneumatically control the operation of a domestic clothes dryer or the like, it is to be understood that the various features of this invention can be utilized singly in any combination thereof to provide control means for other types of apparatus as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIG. 1, the improved control system and method of this invention is generally indicated by the reference numeral 10 and is utilized for controlling the operation of a clothes dryer, generally indicated by the reference numeral 11, having a main burner means 12 adapted to be interconnected to a fuel source manifold 13 by a pneumatically operated valve means 14 in a manner hereinafter described.

The apparatus ;11 includes an electric motor 15 which rotates the clothes-receiving drum (not shown) of the apparatus 11 during the entire cycle of operation of the apparatus 11 in a conventional manner, the electric motor 15 being adapted to be interconnected to power source leads L and L in a manner hereinafter described. The electric motor is adapted to drive an eccentric cam '16 connected to its output shaft 17 as long as the electrical motor 15 is energized whereby the eccentric cam 16 will continuously move a piston rod arrangement 18 to operate a vacuum pump means 19 to provide a continuous vacuum source for the system 10 of this invention as long as the electrical motor 15 is energized, the vacuum pump 19 having its inlet 20 interconnected to a conduit means 21.

The power source lead L is interconnected to a door operated electrical switch blade 22 by a lead 23 whereby the switch blade 22 will be closed against a contact 24 only when the access door of the dryer 11 is disposed in its closed position so as to electrically interconnect the lead 23 to a lead 25 that is interconnected to one side 26 of the electrical motor 15. The other side 27 of the electrical motor is interconnected to a contact 28 by a lead 29. A normally closed, snap switch blade 30 electri- 3 cally interconnects the contact 28 to a lead 31 that is interconnected to a fixed contact 32 on an on-ofl electrical switch 33 for the apparatus 11, the switch 33 being automatically operated by a timer means of the apparatus 11 in a conventional manner.

In particular, when the housewife or the like, desires to utilize the apparatus 11, the housewife sets the timer knob (not shown) of the control system in its selected on position whereby such setting of the control knob of the timer means of the apparatus 11 will close a switch blade 34 against the contact 32 to electrically interconnect a lead 35 to the lead 31, the lead 35 being interconnected to the power source lead L whereby the other side of the electrical motor will be interconnected to the power source lead L as long as the

switch blades

34 and 30 are disposed in their closed position. Thus, if the dryer door is also disposed in its closed position, the power source lead L will be interconnected to the side 26 of the electrical motor 15 so that the electrical motor 15 will be energized to not only drive the clothes-receiving drum of the dryer 11, but also to continuously operate the vacuum pump 19 to automatically control the system 10 in a manner hereinafter described.

The pneumatically operated valve means 14 for interconnecting the fuel source 13 to the main burner means 12 of the apparatus 11 comprises a housing means having a valve seat 36 that interconnects the fuel source 13 to the burner means 12, the valve seat 36 being opened and closed by a valve member 37 that is moved between its open and closed positions by a vacuum operated actuator that is generally indicated by the reference numeral 38 in FIGS. 1 and 2 and comprises a cup-shaped housing member 39 having its open end closed by a flexible diaphragm 40 that is interconnected to the valve member 37 by a tying means 41 in a conventional manner whereby the flexible diaphragm 40 cooperates with the housing 39 to define a chamber 42 therebetween. A compression spring 43 is disposed in the chamber 42 to tend to normally move the flexible diaphragm 40 upwardly as illustrated in FIG. 1 to maintain the valve member 37 in its closed position against the valve seat 56 to prevent any flow of fuel to the main burner means 12. However, when the vacuum source 19 is interconnected to the chamber 42 in a manner hereinafter described to evacuate the chamber 42, the pressure differential acting across the diaphragm 40 moves the diaphragm 40 downwardly in opposition to the force of the compression spring 43 to move the valve member 37 to its open position so that the fuel source 13 will be interconnected to the main burner means 12 as long as the pneumatically operated actuator 48 is in its actuated condition.

The ignition means for the main burner means 12 comprises an ignition coil 44 having one side 35 thereof interconnected by a lead 46 to the lead 35 so that the side 35 of the ignition coil 34 is always interconnected to the power source lead L The other side 47 of the ignition coil 44 is interconnected by a lead 48 to a switch blade 49 that is adapted to close against a contact 50 that is electrically interconnected to the power source lead L by a lead 51 only when a vacuum operated actuator 52 is actuated.

In particular, the vacuum operated actuator 52 comprises a cup-shaped housing 53 having its open end closed by a flexible diaphragm 54 interconnected to the switch blade 49 by a tying means 55, the diaphragm 54 cooperating with the housing means 52 to define a chamber 56 therebetween which receives a compression spring 57 that normally urges the flexible diaphragm 54 upwardly to the position illustrated in FIG. 1 to open the switch blade 49 from the contact 50. However, when the chamber 56 is evacuated by being interconnected to the vacuum source 19 in the manner hereinafter described, the pressure differential acting across the diaphragm 54 moves the diaphragm 54 downwardly in opposition to the force of the compression spring 57 to close the swit h blade 49 against the contact 50 which, in effect, places the ignition coil 44 across the power source leads L and L to energize the same whereby the energized coil 44 can heat up to a temperature that will be sufficient for igniting fuel issuing from the burner means 12 in a conventional igniting manner.

An ignition coil temperature sensing means 58 is provided for the system 10 and comprises a bimetal member 59 that is interconnected to a valve member 60 by a tying means 61, the valve member 60 being disposed in a housing means 62 having a valve seat 63 interconnecting an inlet conduit 64 to an outlet conduit 65. When the bimetal member 59 senses a temperature of the ignition coil 44 below a temperature sufficient for igniting fuel issuing from the main burner means 12, the bimetal member 59 is in such a condition that the same maintains the valve member 60 away from the valve seat 63 to fluidly interconnect the

conduits

64 and 65 together. However, when the ignition coil 44 reaches an ignition temperature, the bimetal member 59 warps in such a manner that the same moves the valve member 60 against the valve seat 63 to terminate the fluid connection between the

conduits

64 and 65. In addition, when the main burner means 12 is operating, the bimetal member 59 also senses the flames at the main burner means 12 so that the same will maintain the valve member 60 in its closed position against the valve seat 63 as long as fuel is burning at the main burner means 12.

Another temperature sensing device 66 is provided for the control system 10 and is adapted to sense the temperature effect of the main burner means 12. The temperature sensing means 66 comprises a bimetal member 67 that is interconnected to a valve member 68 by a tying means 69, the valve member 68 being disposed in a housing means 70 to open and close a valve seat 71 there of that fluidly interconnects the conduit 21 to a conduit 72 that is fluidly interconnected to the conduit 64 of the ignition temperature sensing means 59.

As long as the temperature effect of the burner means 12 of the apparatus 11 is below a predetermined temperature setting of the sensing means 66, the bimetal member 67 maintains the valve member 68 away from the valve seat 71 to fluidly interconnect the

conduits

21 and 72 together whereby if the electrical motor 15 is energized, the vacuum source 19 will be interconnected to the conduit 72. However, when the temperature sensing means 66 senses a temperature eifect of the burner means 12 above the set temperature setting of the thermostatic means 66, the bimetal member 67 warps in a manner to move the valve member 68 against the valve seat 71 and, thus, disconnect the vacuum source 19 from the conduit 72 for a purpose hereinafter described. Of course, it is to be understood that the sensing device 66 could be manually adjustable for temperature selection purposes by the housewife or the like or could be factory set for an optimum drying temperature.

The conduit 72 is interconnected to a port means 73 of a pneumatically operated logic memory unit 74 later to be described, the conduit 72 also being fluidly interconnected to a conduit 75 that leads to a port means 76 of a pneumatically operated logic not unit 77 of this invention.

The conduit 65 leading from the ignition temperature sensing means 59 is interconnected to a one side 78 of a check valve 79 that has the other side 80 thereof interconnected to a conduit means 81 leading to a port means 82 of the logic memory unit 74, the conduit 81 also being interconnected to a conduit means 83 that has a restrictor 84 therein and leads to another port means 85 of the logic memory unit 74. The check valve 79 is so constructed and arranged that a valve seat 86 thereof is adapted to be opened and closed by a valve member 87 so that the valve member 87 will move away from the valve seat 86 to interconnect the

conduits

65 and 81 together when the vacuum source 19 is interconnected to the conduit 65 in a manner hereinafter described. However, when the vacuum source 19 is disconnected from the conduit 65, the valve member 87 is adapted to close the valve seat 86 to prevent fluid .communication between the

conduits

65 and 81 for a purpose hereinafter described.

The conduit 65 is fluidly interconnected to the conduit means 88 that is fluidly interconnected to the chamber 56 of the vacuum operated actuator 52., the conduit 88 also being interconnected to a conduit 89 that leads to the atmosphere by means of a restrictor 90 disposed in the conduit means 89. In addition, the conduit 88 is fluidly interconnected to a conduit 91 having a restrictor 92 therein, the conduit 91 leading to a chamber 93 of an accumulator 94 that is adapted to operate the safety interlock switch blade 30.

In particular, the accumulator 94 comprises a cupshaped housing member 95 having its open end closed by a flexible diaphragm 96 that cooperates with the housing means 95 to define the chamber 93, the flexible diaphragm 96 carrying an actuating post 97 having an elongated slot 98 receiving the switch blade 30 therethrough. A compression spring 99 is disposed in a chamber 93 of the accumulator 9'4 and nonmally tends to maintain the diaphragm 96 in the position illustrated in FIG. 1 so that the switch blade 30 can normally be disposed in its closed position against the contact 28.

However, should the chamber 93 of the accumulator 94 become evacuated in a manner hereinafter described so as to cause the resulting pressure differential across the diaphragm 96 to move the diaphragm 96 downwardly in opposition to the force of the compression spring 99 a suflicient distance, such downward movement of the diaphragm 96 will subsequently take up thelost motion between the switch blade 30 and the slot means 98 of the post means 97 so that the post means 97 will snap the switch blade 30 from its closed position to its open position as illustrated in FIG. 1 so that the switch blade 30 will remain in its open position even though the accumulator 94 can return to the condition illustrated in FIG. 1 by the chamber 93 being subsequently interconnected to the atmosphere.

'A manual reset knob 100 is interconnected to the actuating post 97 by a tying means 101 so that when the switch blade 30 is disposed in its open position as illustr'ated in FIG. 1, the housewife or the like can pull upwardly on the knob 100 and cause the actuating post 97 to move therewith a distance suflicient to snap close the switch blade 30 against the contact 28 so that when the housewife subsequently releases the reset means 100, the actuating post means 97 can return to its normal position as illustrated in FIG. 1 and the switch blade 30 will remain in its closed condition against the contact 28 until the accumulator 94 is again evacuated in a manner hereinafter described to cause an opening of the switch blade 30.

A port means 102 of the pneumatically operated logic memory unit 74 is interconnected by a conduit means 103 to a port means 104 of a pneumatically operated logic and unit 105 of this invention, the logic and unit 105 having a port means 106 thereof interconnected by a conduit means 107 to a port means 108 of the logic not unit 77. Another port means 109 of the logic and unit 105 is interconnected by a conduit means 110 to the chamber 42 of the pneumatically operated actuator 38. The remaining port means 111 of the logic and unit 105 is interconnected by a conduit means 112 to the atmosphere through restrictor 113.

The conduit 65 that leads from the ignition temperature sensing means 58 is fluidly interconnected to a conduit means 114 that leads to a port means 115 of the logic not unit 77. The remaining port means 116 of the logic not unit 77 is interconnected to a conduit means 117 that leads to the atmosphere through a restrictor 118.

As previously stated, the control system is so constructed and arranged that the ignition coil 44 for the burner means 12 must be first energized to a temperature thereof that will be suflicient for igniting fuel issuing from the burner means 12 each time before the actuator 38 will move the valve member 37 from, its closed position to its open position to cause fuel to issue from the main burner means 12.

Thus, since both temperature sensing devices 58 and 66 are disposed in their open position when the control system 10 is initially turned on by the closing of the switch blade 34 against the contact 32, either manually or automatically by a timer clock or the like, the energized electric motor 15 will operate the vacuum pump 19 and since the temperature effect of the apparatus 11 is below the temperature effect setting of the thermostatic device 66, the vacuum pump 19 is adapted to evacuate conduit 72 through the open valve means 68 as well as to evacuate

conduits

81 and 114 leading respectively to the logic memory unit 74 and logic not unit 77.

As illustrated in FIG. 3, the logic and unit will require two vacuum signals from the logic memory unit 74 and logic not unit 77 respectively through conduit means 103 and 107 to cause the logic and unit 105 to direct an output vacuum signal through the conduit means 56 to open the valve means 37 so that the fuel source 13 can be interconnected to the main burner means 12. However, the memory unit 74 must first receive a signal from the conduit means 81 that is caused by the ignition temperature sensing means 58 having its valve member 60 disposed in its open condition before the memory unit 74 will direct its output vacuum signal to the and input 105. The logic not unit 77 also receives the vacuum signal from the open setting of the valve member 60 of the temperature sensing means 58 through the conduit means 114 and will not direct its vacuum output signal through the conduit means 107 to the an unit 105 to cause opening of the valve means 37 for the main burner means 12 until after the signal through conduit 114 is terminated by the closing of the valve member 60 against the valve seat 63 of the ignition temperature sensing means 58 so that the and unit 105 cannot cause opening of the valve means 37 until after the ignition coil 44 has been raised to a temperature proper for ignition of fuel issuing from the burner means 12. Accordingly, the

logic units

74, 77 and 105 require that the valve member 60 must be first in an open position and then be moved to a closed position after each closing of the main valve member 37 before the main valve member 37 can be again opened, the valve member 60 only closing after an open condition thereof when the ignition coil 44 is at a temperature suitable for igniting fuel that will be issued from the main burner means 12.

The details of the

logic units

74, 77 and 105 for accomplishing the above function will now be described in detail whereby reference is now made to FIG. 2.

As illustrated in FIG. 2, the

logic units

74, 77 and 105 are substantially identical in construction whereby only the particular details of the logic memory unit 74 will now be described and like parts of the logic not unit 77 will be indicated by the same reference numerals followed by the reference letter A and the like parts of the logic and unit 105 will be indicated by like reference numerals followed by the reference letter B.

In this manner, it will be appreciated that the logic units of this invention can be made from the same parts in a simple and effective manner while producing different logic functions as will be apparent hereinafter so that the cost of the control system 10 of this invention is relatively small when considering prior known electrical and pneumatic control systems.

As illustrated in FIG. 2, the logic memory unit 74 comprises two

housing parts

118 and 119 suitably secured together to hold two

annular members

120 and 121 beintermediate or central outwardly directed diaphragm portion 125 provided with an outer peripheral portion 126 that is secured and sealed between the

annular members

120 and 121. An outboard smaller diaphragm portion 127 of the diaphragm member 124 has its outer periphery 128 secured and sealed between the housing member 118 and the annular member 120 to define a chamber 129 between the diaphragm portion 127 and the end wall means 122 while cooperating with the larger diaphragm portion 125 to define a chamber 130 between the diaphragm portions 127 and 125. An opposed outboard diaphragm portion 131 of the diaphragm member 124 has its outer periphery 132 secured and sealed between the annular member 121 and the housing member 119 to define a chamber 133 between the diaphragm portion 131 and the end wall means 123 of the housing member 119 while defining a chamber 134 between the

diaphragm portions

131 and 125.

The diaphragm member 124 has a bore 135 interrupting the end 127 thereof so as to receive a compression spring 136 that has one end bearing against the end wall means 122 of the housing member 118 and the other end thereof bearing against the diaphragm member 124 to urge the diaphragm portion 131 against a frusto-conical valve seat 137 that projects inwardly from the end wall means 123 of the housing member 119 into the chamber 133. The valve seat 137 of the logic memory unit 74 is interconnected to the port means 73 that leads to the conduit 72 whereas the valve seat means 137A of the not unit 77 is interconnected to the port means 116 that leads to the conduit means 117 and the valve seat means 137B of the and unit 105 is interconnected to the port means 109 that leads to the conduit means 110.

The diaphragm mmeber 124 has a passage means 138 passing through the diaphragm portion 131 in offset relation to the valve seat 137 so as to always fluidly interconnect the

chambers

133 and 129 together.

The chamber 134 of the memory unit 74 is always interconnected to the atmosphere by a port means 139 formed through the annular member 121 whereby the chamber 134A of the not unit 77 is always interconnected to the atmosphere by the port means 139A and the chamber 134B of the and unit 105 is always interconnected to the atmosphere by the port means 139B.

A frusto-conical valve seat 140 is formed on the housing member 118 so as to project inwardly from the end wall means 122 thereof into the chamber 129 so as to be adapted to be opened and closed by a cooperating portion 141 on the diaphragm member 124. However, the valve seat member 140 of the memory unit 74 has been out off so that the full movement of the diaphragm member 124 from the position illustrated in FIG. 2 toward the valve seat member 140 will never cause closing of the valve seat 140 whereas the

valve seat members

140A and 140B of the

logic units

77 and 105 will be closed off by the

diaphragm portions

141A and 141B when the

respective diaphragm members

124A and 124B are moved toward the

valve seats

140A and 140B in a manner hereinafter described.

Thus, it can be seen that the valve seat 140 of the memory unit 74 always fluidly interconnects the chamber I129 to the port means 85 which is interconnected to the conduit means 83 whereas the valve seat 140A of the not unit 77 is adapted to fluidlly interconnect the chamber 129A to the port means 76 that leads to the conduit means 75 when the diaphragm member 124A is in the position illustrated in FIG. 2 and the valve seat means 140B of the and unit 105 is adapted to interconnect the chamber 129B to the port means 111 that leads to the conduit means 112 when the diaphragm member 1248 is disposed in the position illustrated in FIG. 2.

The chamber 130 of the Memory unit 74 is always in fluid communication with the port means 82 that leads to the conduit 81 whereas the chamber 130A of the Not unit 77 is always fluidly interconnected to the port means 115 that leads to the conduit 114 and the chamber 130B of the And unit is always fluidly interconnected to the port means 105 that leads to the conduit 103.

A controlled bleed to the atmosphere for the

logic units

74, 77 and 105 can be provided in the conduit 72 or in the conduit to reset the same to the position illustrated in FIG. 2 when the valve member 68 closes against the valve seat 63 as will be apparent hereinafter. However, in the embodiment illustrated in the drawings, the conduit 110 is interconnected to the atmosphere at a controlled rate by a conduit 142 having a restrietor 143 therein.

The operation of the control system 10 of this invention will now be described.

Assuming that the dryer door is in its closed position to hold the switch blade 22 against the contact 24 and that the switch blade 30 is also in its closed position against the contact 28 with the accumulator 94 being in its deactuated position as illustrated in FIG. 1, the housewife or the like sets the selector timer knob for operating the dryer 11 for a predetermined length of time whereby the timer mechanism closes and holds the switch blade 34 against the contact 32 and will maintain the switch blade 34 against the contact 32 during the entire cycle of operation of the dryer 11 at the conclusion of which the timer means will automatically open the blade 34 away from the contact 32 to terminate the operation of the apparatus 11.

With the switch blade 34 now moved to its closed position against the contact 32, it can be seen that the electric motor 15 is placed across the power source leads L and L so that the electric motor 15 will continuously rotate the laundry receiving drum to tumble the clothes in an atmosphere to be heated by the burner means 12 for a dnying of the laundry or the like. As the output shaft 17 of the motor means 15 is continuously rotating, the same through the eccentric cam 16 reciprocates suitable pumping mechanism of the vacuum pump 19 to continuously provide a vacuum source for the control system 10.

At the initial operation of the control system 10, not only is the ignition coil 44 not at an ignition temperature, but also the temperature effect of the apparatus 11 is below the temperature setting for the thermostatic means 66 whereby both

valve members

60 and 68 are disposed in their open position as illustrated in FIG. 1 so that the vacuum source 19 will not only be directed to the vacuum operated actuator 32 to evacuate the chamber 56 thereof and close the switch blade 49 against the contact 50 to place the ignition coil 44 across the power source leads L and L but also the vacuum source 19 is interconnected to the valve seat I137 of the Memory unit 74, to chamber 129A of the Not unit 77, to chamber 130 of the Memory unit 74 through the one way check valve means 79 and to the chamber 130A of the Not unit 77.

Since the vacuum source is interconnected to the chamber 130A of the Not unit 77, the pressure differential created across the intermediate diaphragm portion thereof causes the diaphragm member 124A to move downwardly in opposition to the force of the compression spring 136A so the diaphragm portion 141A closes off the valve seat 140A and opens the valve seat 137A to interconnect the atmosphere from conduit 117 into the chamber 133A thereof and, thus, to chamber 133B of the And unit 105.

With the vacuum source :19 now being interconnected to chamber of the Memory unit 74, the resulting pressure differential across the intermediate diaphragm portion 125 thereof causes the diaphragm member 124 to move upwardly in opposite to the force of the compression spring 136 to open the valve seat 137 and thereby interconnect the vacuum source to the chamber 133 of the Memory unit 74 and, thus, by means of the conduit 103, to the chamber 130B of the And unit 105. With the vacuum source 19 now interconnected to chamber 130B of the And unit 105, the resulting pressure differential across the diaphragm portion 125B thereof moves the diaphragm member 124B of the And unit 105 downwardly in opposition to the force of the compression spring 136B so that the diaphragm portion 141B closes the valve seat 140B leading to the atmosphere through the conduit means 112 while opening the valve seat 137B. However, since the chamber 133B of the And unit 105 is now interconnected by the conduit 107 to the chamber 133A of the Not unit 77, and since chamber 133A of the Not unit 77 is interconnected to the atmosphere by the open valve seat 137A thereof, the chamber 42 of the actuator 38 remains interconnected to the atmosphere so that the valve member 37 remains in its closed position against the valve seat 36 to prevent my flow of fuel from the manifold 13 to the main burner means 12.

When the diaphragm member 124 of the Memory unit 74 is moved upwardly in FIG. 2 by the vacuum source being interconnected to the chamber 130 thereof, the part 141 of the diaphragm member 124 cannot close off the valve seat '140 and the vacuum being created in chamber 133 by the opened valve seat 137 causes evacuation of the chamber 129 of the Memory unit 74 by means of the passage means 138 in the diaphragm member 124.'The vacuum now created in the chamber 129 interconnects up with the vacuum in chamber 130 by means ofthe conduit means 83 and restrictor 84 so as to provide a holding circuit for maintaining the diaphragm member 124 of the Memory unit 74 in its up position even during the subsequent absence of a vacuum signal in the conduit 25 which will permit the check valve 79 to close and maintain the vacuum signal in the chambers 130 and 129.

In particular, it can be seen that initially when the diaphragm member 124 of the Memory unit 74 is moved to its up position, the diaphragm member 124A of the Not unit 77 is moved to its down position and the diaphragm member 124B of the And unit 105 is moved to its down position whereby the atmosphere in the chamber 133A of the Not unit 77 is elfectively interconnected to the chamber 42 of the actuator 38 so that the main valve member 37 remains closed against the valve seat 36.

Under the above described condition, the ignition coil 44 is being energized and when the same reaches a predetermined temperature that is sufiicient for ignition purposes, the ignition temperature sensing means 59 causes the valve member 60 to move to its closed position against the valve seat 66 to disconnect the vacuum source 19 from the conduit means 65 and 114 while interconnecting the atmosphere to the same by means of the restrictor 90 in the conduit means 89 so that the conduit means 65 and 114 will be bled to atmospheric pressure.

However, the check valve 87 now moves against the valve seat 86 to prevent the bleed of air into the conduit '81 that leads to the chamber 130 of the memory unit 74 so that the diaphragm member 12 4 thereof remains in its up position to still interconnect the vacuum source conduit 72 to the chamber 133 thereof and, thus, to the chamber 130B of the and unit 105 to maintain the diaphragm member 124B thereof at its down position to interconnect the chamber 133B to the chamber 42 of the actuator 38.

The bleed of air into the conduit means 114 begins to bleed air into the chamber 130A as the not unit 77 so that when the bleed of air into the chamber 130A sufliciently reduces the pressure differential across the intermediate diaphragm portion 125A thereof, the compression spring 136A moves the diaphragm member 124A back to the back position illustrated in FIG. 2. In this manner, the vacuum source in the conduit 72 is now interconnected to the chamber 129A through the opened valve seat 140A and, thus, is interconnected to the chamber 133A of the not unit 77 by the passage means 138A in the diaphragm member 124A. With vacuum source 19 now being interconnected to the chamber 133A of the not unit 77 and with the atmosphere being disconnected from the chamber 133A by the valve member 124A closing against the valve seat 137A, vacuum is source 19 is disconnected from the conduit 65 and, thus,

from the chamber 56 of the actuator 52 so that the bleed of air into the conduit 88 from the restrictor permits the chamber 56 in the actuator 52 to return to atmospheric condition and open the switch blade 49 to terminate the source of current to the coil 44. However, since the coil 44 is still at a temperature suflicient to ignite fuel issuing from the burner means 12, the now opened valve means 14 issues fuel from the burner means 12 which is ignited by the heated ignition coil 44. If the fuel from the burner means 12 is properly ignited by the ignition coil 44, the temperature sensing means '59 of the sensing device 58 maintains the valve member 60 against the valve seat 63 during the burning of fuel at the main burner means 12 whereby the main burner means 12 continues to burn until the temperature effect thereof reaches the temperature effect being sensed by the sensing means 66. At this time, the bimetal member 67 moves the valve member 68 against the valve. seat 71 to disconnect the vacuum source 19 from the conduit means 72 and 75 to cause closing of the valve member 37 in a manner now to be described.

With the vacuum source 19 now disconnected from conduit 72 by the closing of the valve member 68 against the valve seat 71, the system bleeds down by air passing through the restrictor 143 and into conduit 142 and, thus, into conduit to de-actuate the actuator 38 to close the valve member 37 against the valve seat 36 and thereby terminate the flow of fuel to the main burner means 12. Thi s'bleed of air into the conduit 110 also bleeds into chamber 133B of the and unit 105 and by conduit 107 into chamber 133A, passage 138A and chamber 129A of the not unit 77 so as to pass through the opened valve seat 140A and into

conduits

75 and 72 that lead to the chamber 133 of memory unit 74. Chamber 133 now bleeds air into chamber 129 by the passage 138 in the diaphragm member 124 and, thus, into chamber 130 through restrictor 84 and conduit means 83 to return the memory unit 74 to the condition illustrated in FIG. 2. Similarly, with atmosphere now in the chamber 133 of the memory unit 74, atmosphere is directed to chamber 130B of the and unit 105 to cause the same to return to the condition illustrated in FIG. 2 whereby the entire control system 10 is turned off except that the electric motor 15 is continuing to operate to tumble the laundry in the heated atmosphere of the dryer 11.

The temperature effect in the dryer 11 now begins to drop because of the terminated operation of the main burner means 12. When the dropping temperature eifect fails below the predetermined temperature setting of the thermostatic device 66, the bimetal member 67 again moves the valve member 58 to its open position to interconnect the conduit 21 to the conduit 72. When the flames ceased to exist at the main burner means 12 when the same was turned oif by the closing of the valve member 37 in the manner previously described, the bimetal member 59 moved the valve member 60 to its open position as illustrated in FIG. 1 whereby the previously described cycle of operation for energizing the ignition coil 44 and the subsequent opening of the valve member 37 is remated in the manner previously described to again cause operation in the main burner means 12.

Thus, it can be seen that the system 10 of this invention can cycle the main burner means 12 on and off in the manner previously described to tend to maintain the temperature effect in the dryer 11 at the temperature effect setting of the thermostatic device 66 until the timer opens the switch blade 34 to de-energize the motor 15 and, thus, turn off the vacuum source 19 whereby the entire system will bleed down through the restrictor means 45, 113, 118, and 143 in the manner previously described so that the valve means 37 will be maintained in its closed position and the switch blade 34 will be disposed in its open position.

If during the previously described ignition cycle for the main burner means 12, when the

valve members

60 and 68 of the temperature sensing device 58 and 66 are respectively disposed in their open condition to cause the actuator 52 to close the switch blade 49 across the contact 50 for energizing the coil 44, the coil 44 after having closed the valve memebr 50 against the valve seat 63 to permit subsequent opening of the main valve member 37 in the manner previously described does not cause ignition of the main burner means 12 even though the valve member 37 is now disposed in its open position, the bimetal member 59 will cool and open the valve member 60 away from the valve seat 63 because no flame is appearing at the main burner means 12 and because the ignition coil 44 is cooling whereby the vacuum source 19 is again interconnected to the actuator 52 to close the valve member 49 to energize the ignition coil 44 and repeat the ignition cycle. However, during the time the valve member 60 is open, the vacuum source is also being conected by restrictor 92 to the chamber 93 of the accumulator 94 so that after a predetermined time period, the evacuation of the chamber 93 has caused the diaphragm 96 to move downwardly in opposition to the force of the compression spring 99 and cause the actuating post 97 thereof to snap the switch blade 90 from its closed position to its open position to thereby terminate the operation of the motor means 15 and, thus, the entire system until the switch blade 30 is moved back to its closed position by the manual reset knob 100 in the manner previously described.

Thus, it can be seen that a vacuum signal is being directed to the accumulator 94 each time a vacuum signal is interconnected to the igniter actuator 52 each time the ignition coil 44 is recycled in unsuccessful ignition attempts at the main burner means 12 so that after a predetermined number of such unsuccesful attempts, the accumulator 94 will move the diaphragm 96 downwardly to open the switch blade 30 so that an adverse number of unsuccessful attempts will not be permitted by the system 10 to cause an adverse amount of raw gas to issue from the burner means 12 of the apparatus 11.

If during the normal cycle of operation of the control system 10 in the manner previously described, the housewife or the like should open and then close the access door for any reason, such opening of the door will open switch blade 22 to stop the electric motor and, thus, terminate the vacuum source 19 so that the system 10 will bleed down to the off condition of FIG. 2. However, the housewife after opening such access door may quickly shut the same to again energize the electric motor 15. When the access door is thus momentarily opened, the vacuum source 19 is terminated permitting the entire pneumatic control system to bleed down to atmospheric conditions by means of the

restrictors

35, 113, 118, and 143 in the manner previously described so that the pre viously created vacuum in the chambers 130 and 129 of the Memory unit 74 will cease to exist and the diaphragm member 124 will be moved downwardly to the position illustrated in FIG. 2 by the force of the compression spring 136, so as to prevent the occurrence of a Memory unit output vacuum signal in the chamber 133 thereof until a vacuum signal is again created in the conduit 81 in the manner previously described. The closing of the access door restarts the main motor 15 and restores the vacuum source 19. However, due to the construction and location of the bimetal member 59 of the flame sensing device 58, the bimetal member 59 is still warm because of a thermal lag therein and acts as if a main burner flame at the burner means 12 is still present so that the valve member 60 remains against the valve seat 63 during the intermittent opening and closing of the access door during the normal cycle of operation of the apparatus 11. Accordingly, the main thermostatic means 66 is now sensing a temperature effect in the apparatus 11 below the predetermined temperature effect so that the valve member 68 thereof is moved to an open position as illustrated in FIG. 1 to interconnect the vacuum source 19 to the conduit means 72 and 75 leading to the memory unit 74 and not unit 77.

However, the memory unit 74 of this invention can not move from the position illustrated in FIG. 2 to its up position to interconnect the vacuum now in the conduit 72 to the chamber 133 thereof and, thus, to move the diaphragm member 124B of the and unit downwardly from the position illustrated in FIG. 2 until a vacuum signal is directed to the chamber 130 thereof by the subsequent opening of the valve member 60 of the flame sensing means 58.

Thus, before the valve member 60 of the flame sensing means 68 opens, the vacuum being created in chamber 129A and, thus, in chamber 133A of the not unit 77, although being directed to the chamber 1333 of the and unit 105, cannot be directed to the actuator 38 to open the main valve member 37 because the memory unit 74 is not directing a vacuum signal through the con duit 103 to chamber 13013 of the and unit so that the compression spring 13613 of the and unit 105 holds the diaphragm member 124B against the valve seat 137B to prevent any vacuum to be supplied to the chamber 42 of the actuator 38.

Therefore, the main gas valve 37 will remain closed until such time as the bimetal member 69 cools so as to open the valve member 60 to furnish a vacuum signal to actuate the igniter actuator 52 while resetting the memory unit 74 to its diaphragm up position and the not unit 77 to its diaphragm down position. The actuated actuator 52 energizes the ignition coil 44 so that the bimetal member 59 will again be heated to close the valve 60 against the valve seat 63 and, thus, change the signal to the not unit 77 that permits the and unit to again open the valve member 37 in the manner previously described.

Thus, it can be seen that under any conditions of the control system 10 of this invention, in order for the main valve member 37 to be moved to its open condition to supply a flow of fuel from the fuel source 13 to the main burner means 12, the memory unit 74 must first be subjected to a pneumatic signal indicating that the valve member 60 of the flame sensing means 58 is moved to an open condition thereof after the last closing of the valve member 37 and the not unit 77 then requires the valve member '60 to move to a closed condition thereof so as to change the signal to the not unit 77 in a manner to cause the and unit 105 to open the main valve member 37. In this manner, each time before the main valve member 37 can be moved to its open condition to direct fuel to the main burner 12, the ignition actuator 52 must energize the ignition coil 44 to such a temperature that the same will cause a closing of the valve member 60 of the temperature sensing means 58.

Accordingly, it can be seen that this invention provides an improved pneumatic control system and method for operating the same as well as improved parts for such a control system or the like.

While the form of the invention now preferred has been described as required by the statutes, other forms may be utilized which come within the scope of the claims which follow.

What is claimed is:

1. A pneumatic control system for a fuel burning apparatus having burner means adapted to be interconnected to a source of fuel comprising a source of pneumatic fluid, pneumatically operated ignition means for said burner means, interconnecting means for interconnecting said fuel source to said burner means, pneumatically operated valve means for controlling the flow of fuel from said fuel source to said burner means through said interconnecting means, means for interconnecting said pneumatic source to said pneumatically operated ignition means to operate the same every time before said pneumatically operated valve means is opened, and means for interconnecting said pneumatic source to said pneumatically operated valve means to operate the same for interconnecting said fuel source to said burner means only after said ignition means has been pneumatically operated for igniting said burner means.

2. A pneumatic control system as set forth in claim 1 wherein said pneumatic source is a vacuum source.

3. A pneumatic control system as set forth in claim 1 wherein said apparatus is a clothes dryer having an electrical motor for driving a clothes receiving drum thereof, said pneumatic source comprising a vacuum pump interconnected to said motor to be driven thereby.

4. A pneumatical control system as set forth in claim 1 wherein said means for interconnecting said pneumatic source to said pneumatically operated ignition means comprises a thermostatically operated valve means.

5. A pneumatic control system as set forth in claim 4 wherein said thermostatically operated valve means closes to disconnect said source from said pneumatically operated ignition means when said ignition means is activated to a predetermined degree for subsequent ignition of fuel issuing from said burner means.

6. A pneumatic control system as set forth in claim 5 wherein said thermostatically operated valve means remains closed after ignition of said burner means as long as said thermostatically operated valve means senses flame means at said burner means.

7. A pneumatic control system as set forth in claim 1 wherein said means for interconnecting said pneumatic source to said pneumatically operated valve means comprises a thenmostatically operated valve means.

8. A pneumatic control system as set forth in claim 7 wherein said means for interconnecting said pneumatic source to said pneumatically operated ignition means comprises another thermostatically operated valve means.

9. A pneumatic control system as set forth in claim 8 wherein said other thermostatically operated valve means can interconnect said pneumatic source to said pneumatically operated ignition means only when said first-named thermostatically operated means is in an open condition to be adapted to interconnect said pneumatic source to said pneumatically operated valve means.

10. A pneumatic control system as set forth in claim 1 wherein means are provided for automatically turning olf said control system when said ignition means fails to ignite said burner means after a predetermined number of attempts to ignite the same.

11. A pneumatic control system as set forth in claim 1 wherein a pneumatically operated logic memory unit provides an output pneumatic signal from said pneumatic source only when said memory unit activated by said means interconnecting said pneumatic source to said pneumatically operated ignition means, said memory unit being deactivated each time said pneumatically operated valve means disconnects said fuel source from said burner means whereby said unit terminates its output pneumatic signal until reactivated by said means interconnecting said pneumatic source to said pneumatically operated ignition means, said output pneumatic signal being required before said means for interconnecting said pneumatic source to said pneumatically operated valve means can interconnect said pneumatic source to said pneumatically operated valve means.

12. A pneumatic control system as set forth in claim 11 wherein a pneumatically operated logic not unit provides an output signal from said pneumatic source only when said not unit is deactivated by said means for inter connecting said pneumatic source to said pneumatically operated ignition means disconnects said pneumatic source from said pneumatically operated ignition means, said not unit being activated only when said means for interconnecting said pneumatic source to said pneumatically operated ignition means is interconnecting said pneumatic source to said pneumatically operated ignition means, said output pneumatic signal from said not unit and said output pneumatic signal from said memory unit both being required before said means for interconnecting said pneumatic source to said pneumatically operated valve means can interconnect said source to said pneumatically operated valve means.

13. A pneumatic control system as set forth in claim 12 wherein said means for interconnecting said pneumatic source to said pneumatically operated valve means comprises a pneumatically operated logic and unit which receives said output pneumatic signals from said memcry and not units, said and unit only being activated when receiving said output pneumatic signal from said memory" unit and being adapted only when activated to direct said output signal from said not unit to said pneumatically operated valve means to operate the same for interconnecting said fuel source to said burner means.

14. A pneumatic control system as set forth in claim 13 wherein each logic unit has a one-piece diaphragm member provided with three spaced diaphragm portions defining four fluid receiving chambers in said unit.

15. A pneumatic control system as set forth in claim 14 wherein each diaphragm member has passage means formed therethrough for fluidly interconnecting togetherthe two out board chambers of the respective unit.

16. A method for pneumatically operating a fuel burning apparatus having burner means adapted to be interconnected to a source of fuel comprising the steps of providing a source of pneumatic fluid, providing pneumatically operated ignition means for said burner means, providing pneumatically operated valve means for controlling the flow of fuel from said fuel source to said burner means, interconnecting said pneumatic source to said pneumatically operated ignition means to operate the same every time before said pneumatically operated valve means is opened, and interconnecting said pneumatic source to said pneumatically operated valve means to operate the same for interconnecting said fuel source to said burner means only after said ignition means has been pneumatically operated for igniting said burner means.

17. A method as set forth in claim 16 wherein said pneumatic source is a vacuum source.

18. A method as set forth in claim 16 wherein said apparatus is a clothes dryer having an electrical motor for driving a clothes receiving drum thereof and including the step of interconnecting a vacuum pump to said motor to be driven thereby to provide said pneumatic source.

19. A method as set forth in claim 16 wherein said step of interconnecting said pneumatic source to said pneumatically operated ignition means comprises the step of interconnecting the same together by opening a thermostatically operated valve means.

20. A method as set forth in claim 19 and including the step of disconnecting said source from said pneumatically operated ignition means by closing said thermostatically operated valve means when said ignition means is activated to a predetermined degree for subsequent ignition of fuel issuing from said burner means.

21. A method as set forth in claim 20 and including the step of maintaining said thermostatically operated valve means in its closed condition after ignition of said burner means as long as said thermostatically operated valve means senses flame means at said burner means.

22. A method as set forth in claim 16 wherein said step of interconnecting said pneumatic source to said pneumatically operated valve means comprises the step of interconnecting the same together by opening a thermostatically operated valve means.

23. A method as set forth in claim 22 wherein said step for interconnecting said pneumatic source to said pneumatically operated ignition means comprises the step of interconnecting the same together with another thermostatically operated valve means.

24. A method as set forth in claim 23 and including the step of interconnecting said pneumatic source to said pneumatically operated ignition means by said other thermostatically operated valve means only when said first-named thermostatically operated valve means is in an open condition so as to be adapted to interconnect said pneumatic source to said pneumatically operated valve means.

25. A method as set forth in claim 16 and including the step of automatically turning off said control system when said ignition means fails to ignite said burner means after a predetermined number of attempts to ignite the same.

26. A method as set forth in claim 16 and including the step of providing an output pneumatic signal from said pneumatic source by a pneumatically operated logic memory unit only when said memory unit is activated by said step of interconnecting said pneumatic source to said pneumatically operated ignition means, and deactivating said memory unit each time said pneumatically operated valve means disconnects said fuel source from said burner means whereby said memory unit will terminate the output pneumatic signal until reactivated by said step of interconnecting said pneumatic source to said pneumatically operated ignition means, said output pneumatic signal being required before said step of interconnecting said pneumatic source to said pneumatically operated means can take place.

27. A method as set forth in claim 26 and including the step of providing an output signal from said pneumatic source by a pneumatically operated logic not unit only when said not unit is deactivated by said pneumatic source being disconnected from said pneumatically operated ignition means, and activating said not unit only when said step of interconnecting said pneumatic source to said pneumatically operated ignition means takes place, said output pneumatic signal from said not unit and said output pneumatic signal from said memory unit both being required before said step of interconnecting said pneumatic source to said pneumatically operated valve means can take place.

28. A method as set forth in claim 27 and including the step of directing said output pneumatic signal from said not unit to said pneumatically operated valve means to operate the same for interconnecting said fuel source to said burner means when a pneumatically operated logic an unit receives said output pneumatic signals from said memory and not units and is activated by receiving said output pneumatic signal from said memory unit.

29. A method as set forth in claim 28 and including the step of defining four fluid receiving chambers in each logic unit by a one-piece diaphragm member being disposed therein and being provided with three spaced diaphragm portions.

30. A method as set forth in claim 29 and including the step of forming a passage means through each diaphragm member to fluidly interconnect together the two outboard chambers of the respective unit.

31. A control means comprising a condition responsive valve means, a pneumatically operated logic unit having pneumatic signal input means separate from pneumatic signal output means, and passage defining means fluidly interconnecting said valve means with said unit, said valve means opening said passage means to said unit when sensing a certain condition and closing said passage means when sensing another condition, said logic unit being adapted to cotrol a fuel burner by the signal output means thereof and said condition responsive valve means being responsive to conditions of said fuel burner.

32. A control means as set forth in claim 31 and including a pneumatically operated actuator, and means fluidly interconnecting said actuator to said passage means intermediate said logic unit and said condition responsive means.

33. A control means as set forth in claim 31 and including a pneumatically operated valve means, and means fluidly interconnecting said logic unit to said pneumatically operated valve means.

34. A control means as set forth in claim 31 and including a pneumatic source creating device, and means fluidly interconnecting said source creating device to said valve means whereby said source creating device is interconnected to said logic unit when said valve means is opened.

35. A control means as set forth in claim 31 and including at least one other pneumatically operated logic unit, and means fluidly interconnecting said logic units together.

References Cited UNITED STATES PATENTS 2,382,216 8/1945 Eskin et a1. 43167 3,384,071 5/1968 Body et al 126-273 EDWARD G. FAVORS, Primary Examiner U.S. Cl. X.R.