PUMP DRIVING VALVE DEVICE

Abstract

 A pump driving valve device for driving a valve (13) by means of hydraulic pressure produced by an electromagnetic pump (12), comprising an actuator for concurrently driving a plurality of loads such as valves. This device can open or close a plurality of valves (13) connected in series with a main passage via a single valve driving device, can control an arbitrary valve proportionally, and can obtain a safe pump operation.

Description

FIELD OF ART

[0001] This invention relates to an actuator which uses fluid pressure generated by means of an electromagnetic pump to drive valves or the like, and more particularly, to a pump drive valve device for simultaneously driving a plurality of loads.

BACKGROUND OF ART

[0002] In the past, for example, in a gas combustor, it has been necessary that a main valve and a main gas valve are provided in series in a gas supply system leading to a main burner, and a pilot gas valve is provided in a gas supply system leading to a pilot burner branched from the intermediate portion therebetween. In the conventional systems, independent electromagnetic valves have to be used for the main valve, the main gas valve and the pilot gas valve, respectively, and piping and a circuit for performing control in accordance with the determined sequence become complicated. For the main valve, a directly moving type proportional electromagnetic valve is used but this valve requires a great stroke so that an axially lengthy magnetic coil must be used and there poses an inconvenience in that the reliability of the operation is poor.

[0003] Further, there is a composite actuator wherein two pressure chambers are provided, each chamber being provided with responsive members which are different in actuating pressure from each other whereby during the process that pressure on the discharge side of the electromagnetic pump increases, the first responsive member is first driven and then the second responsive member is proportionally actuated. In this composite actuator, the range of pressure at which the second responsive member is proportionally actuated is limited to the range from the actuating pressure of the first responsive member to the maximum discharge pressure of the electromagnetic pump, and a large capacity electromagnetic pump has to be used in order to increase said proportional range.

DISCLOSURE OF THE INVENTION

[0004] It is an object of the present invention to provide a pump drive valve device wherein two valve means provided in a main flow passage in a mutually series relation are redundantly actuated to be opened and closed by means of a single valve drive device, and a suitable valve means can be proportionally controlled.

[0005] It is a further object of the present invention to provide a pump drive valve device which can always assure that an on/off valve is open or closed.

[0006] According to one aspect of the present invention, there is provided a pump drive valve device comprising a first chamber and a second chamber in communication with a suction side and a discharge side, respectively, of an electromagnetic pump, a communicating passage to communicate said first and second chambers with each other, a flow control member provided on said communicating passage to maintain pressure within said second chamber at a predetermined value, a responsive member displaced in sense to the pressure within said second chamber, and a first valve device actuated to be opened and closed by displacement of said responsive member, wherein said first valve device is maintained at its open position by maintaining the pressure within said second chamber at a predetermined value when said electromagnetic pump is actuated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] 

Fig. 1 is a block diagram of a combustor to which a control valve according to one embodiment of the present invention is applied.

Fig. 2 is a chart showing the corresponding relation between pressure within a pressure chamber of the control valve and the operation of each of valves.

Fig. 3 is a circuit diagram of a control circuit for controlling the same.

Fig. 4 illustrates voltage waveforms of output signals in the control circuit of Fig. 3.

Fig. 5 is a plan view showing a part of the control valve in accordance with one embodiment of the present invention.

Fig. 6 is a sectional view taken on line A-A of Fig. 5.

Fig. 7 is a plan view showing two valve actuating mechanism of the control valve.

Figs. 8 and 9 are longitudinal sectional views of the other part in Fig. 5.

Fig. 10 is a longitudinal sectional view showing a gas flow control device in accordance with another embodiment of the present invention.

Fig. 11 is a block diagram of a gas combustor including the gas flow control device of Fig. 10.

Fig. 12 illustrates the operating sequence of the gas combustor in Fig. 11.

Fig. 13 is a block diagram showing a gas combustor to which a gas flow control device in accordance with the present invention is applied.

Figs. 14a and 14b are graphs showing the relation between the drive signal of the gas flow control device and the pressure.

Fig. 15 is a longitudinal sectional view of a flow control device provided with an actuator in accordance with another embodiment of the present invention.

Fig. 16 is a longitudinal sectional view showing a valve of the actuator in Fig. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The embodiments of the present invention will now be described with reference to the drawings. Fig. 1 shows the construction of a gas hot water supply device to which a control valve of the present invention is applied, the device comprising a pilot burner 1, a main burner 2 and a heat exchanger 3. A controller 4 receives a heat demand signal and after a predetermined period of prepurge time, transmits an actuating signal to an igniter 5 and a control valve CV. The control valve CV comprises three valves Vl, V2 and V3, which correspond to a main valve, a pilot gas valve and a main gas valve, respectively, and a valve drive device for driving said valves, that is, an actuator VA. When a first actuating signal is received, the actuator VA first causes the first and second valves Vl and V2 to open whereby gas is supplied to the pilot burner 1 to provide an ignition trial by means of a spark generated by the output of the igniter 5 which has been actuated. When the pilot burner 1 takes place the ignition within a preselected period of ignition trial time, a flame detector 6 detects such ignition to feed an ignition detection signal to the controller 4. When said ignition detection signal is received, the controller 4 transmits a second actuating signal to the control valve CV whereby the third valve V3 is opened by the actuator VA.

[0009] The actuator VA, while being supplied with the first actuating signal from the controller 4, maintains pressure within a pressure chamber which will be described in detail later at a first value to thereby open the first and second valves Vl and V2. When a second actuating signal is supplied to the actuator, the actuator causes the pressure within the pressure chamber to elevate from the first value to a second value to open the third valve V3 while maintaining the first and second valves Vl and V2 in their open state. Fig. 2 shows the relationship between the pressure within the pressure chamber and the opening operation of the valves Vl, V2 and V3. When the ignition is taken place after the prepurge time Tl from the start time and the ignition is detected within the next time T2, the third valve V3 opens.

[0010] An example of a drive circuit for the control valve CV is shown in Fig. 3. In Fig. 3, the reference character E denotes an AC power source, Sl a start switch, Dl a diode, Rl a resistor and S2 a changeover contact. The start switch Sl and the contact S2 can be mechanical such as relay contacts or can be semiconductor switches such as a thyristor. The contact S2 is controlled so that it is turned on at a low pressure Pl while being turned off at a high pressure P2.

[0011] In the operating sequence shown in Fig. 2, when the prepurge time is terminated into the ignition trial time, the start switch Sl and contact S2 are simultaneously turned on. In this state, a positive voltage corresponding to a half wave on the positive side of an alternating current rectified by the diode Dl and a negative voltage applied through the resistor Rl and contact S2 in a period corresponding to a half wave on the negative side are alternately applied to the input end of the control valve CV. This voltage waveform is shown in Fig. 4(A). In case that the first actuating signal having the voltage of such waveform is supplied, when a plunger of an electromagnetic pump of the control valve CV is moved, after moved in one direction by the voltage on the positive side, in a direction opposite thereto, the speed of the plunger is increased by the voltage on the negative side to thereby reduce an output pressure of the electromagnetic pump. A crest value of the voltage on the negative side is determined by the magnitude of the resistor Rl connected in parallel with the diode Dl, and thus, by suitably selecting said value, the output pressure in the low output pressure state of the electromagnetic pump may be suitably set. Also, when the ignition trial time is terminated, at which time the flame is detected, the contact S2 is turned off and the second actuating signal of the voltage corresponding to a half wave of an alternating current of the waveform as shown in Fig. 4(B) is supplied to the input end of the control valve CV.

[0012] It is noted that the first and second actuating signals can be signals which are different in frequency from each other. In this case, a pressure differential is produced by a difference of the moving speed of the plunger of the electromagnetic pump.

[0013] An example of the detailed construction of the control valve CV is shown in Figs. 5 to 9. Housed in a casing indicated as at 11 are an electromagnetic pump 12, three valves 13, 14, 15 which constitute a first, second and third valve Vl, V2, V3, respectively, and two responsive members 16, 17.

[0014] The electromagnetic pump 12 comprises a coil 18 to which an actuating signal from the controller 4 is supplied, and a plunger 19 for reciprocal movement in a center portion of the coil 18, and two check valves 21 and 22 are provided within a communicating hole 20 which extends through the center of the plunger 19. Thus, upon reciprocal movement of the plunger 19, fluid (for example, oil) within a first chamber 23 in communication with the suction side is moved to a pressure chamber, that is, a second chamber 24 in communication with the discharge side to increase pressure therein. The second chamber 24 is also communicated with a third chamber 25 through a communicating passage 26 (Fig. 5) and thus the pressure within the third chamber 25 also increases. The second chamber 24 is further communicated with the first chamber 23 independently of the communicating hole 20 within the plunger 19 through a communicating passage not shown which is provided with a flow control member 27 for maintaining pressure within the second chamber 24 at a predetermined value. This flow control member 27 can be of a needle valve which manually or automatically adjusts an opening area of the communicating passage or can be an orifice having a predetermined opening.

[0015] The first responsive member 16 displaced in sense to pressure within the second chamber 24 is connected to the valve 13 by means of a shaft 31. The valve 13 is normally urged against a valve seat 33 by the action of a spring 32 disposed in the casing 11 but as the responsive member 16 moves downwardly as viewed in Fig. 6 by increase in pressure within the second chamber 24, the valve 13 is moved away from the valve seat 33 against the spring 32, and in this condition, the gas introduced into an inlet passage 34 flows into a distribution passage 35.

[0016] During the movement of the shaft 31 along with the responsive member 16, the shaft 31 causes a first valve actuating mechanism to be actuated. As shown in Figs. 7 and 8, the valve actuating mechanism 41 is rotatable about the shaft 42 supported on the casing 11 and has a lever 44 urged by means of a spring 43 for pivotal movement clockwise in Fig. 8. The lever 44 engages the shaft 31 at one end and supports the second valve 14 at the other end. Thus, when the lever is pivotally moved counterclockwise in Fig.8 during the downward movement of the shaft 31, a pilot passage 45 formed in the casing 11 comes into communication with the distribution passage 35 to supply the gas to the pilot burner. When the pressure within the second chamber 24 lowers, the responsive member 16 is returned to its original position by the action of the spring 32 and the valves 13 and 14 are also returned to their closed position.

[0017] On the other hand, the second responsive member 17 displaced in sense to pressure of the third chamber 25 is secured to one end of a shaft 51, to the other end of which is secured a movable member 54 which is movable within a dash pot 52 filled with oil and urged by means of a spring 53. The movable member 54 has a small hole 55 through which oil within the dash pot 52 can flow in a limited flow rate and therefore, the member 54 is moved slowly within the dash pot 52. For this reason, when pressure within the third chamber.25 increases and the responsive member 17 is moved downwardly, the movement of the movable member is effected at a low speed. This delaying action is also effected when the movable member is returned to its original position by the action of the spring 53.

[0018] Further, a valve actuating mechanism 61 is provided which includes a lever 62 engaging a stepped portion 51a of the shaft 51 during the downward movement in Fig. 6 of the shaft 51. As shown in detail in Figs. 7 and 9, the lever 62 is pivotable about a shaft 63 supported on the casing 11 and urged for clockwise pivotal movement in Fig. 9 by means of a spring 64 disposed in the casing 11, said lever 62 supporting a valve 15 at one end. Thus, if the responsive member 17 is at a position where the former moved up to its upper limit, the valve 15 is urged against a valve seat 65. When pressure within the third chamber 25 increases, the responsive member 17 and the shaft 51 move down at a low speed and the stepped portion 51a comes to contact with the upper surface of the lever 62, then the thereafter downward movement of the shaft 51 causes the lever 62 to be pivotally moved counterclockwise (Fig. 9), the valve 15 is gradually moved away from the valve seat 65 to bring a main passage 66 in communication with the main burner into communication with the distribution passage 35.

[0019] In the control valve constructed as described above, when the first actuating signal is transmitted to the coil 18 of the electromagnetic pump 12, the plunger 19 feeds under pressure the fluid within the first chamber 23 to the second chamber 24 and the third chamber 25, and said fluid is circulated in such a manner that the fluid is returned to the first chamber 23 while receiving a determined resistance whereby the pressure of the second chamber 24 and third chamber 25 increases up to the first value. Pressure developed within the second chamber 24 acts to force the responsive member 16 downwardly in Fig. 6 whereby the valves 13 and 14 are simultaneously opened to supply gas to the pilot burner. While pressure developed within the third chamber 25 acts to force the responsive member 17 downwardly, the responsive member 17 is not displaced by said pressure. However, when the pressure within the third chamber 25 increases up to the second value by transmitting the second actuating signal to the coil 18, the responsive member 17 begins its gradual downward movement under the decelerating action of the dash pot 52 and the valve 15 begins to open at the time when the stepped portion 51a of the shaft 51 is moved down to the position in which the stepped portion engages the lever 62 to begin the gradual supply of gas to the main burner. Such an operation can be positively effected by selecting the spring constant of the returning springs 32 and 53 which act on the responsive members 16 and 17, respectively, to a suitable value.

[0020] Fig. 10 shows a gas flow control device in accordance with another embodiment of this invention, in which an electromagnetic pump 12 is housed in a casing as indicated at 11. The electromagnetic pump 12 comprises a coil 18 to which a drive signal is transmitted and a plunger 19 for reciprocal movement in the center portion of the coil 18 whereby upon the reciprocal movement of the plunger 19, fluid (for example, oil) within the first chamber 23 in communication with the suction side is fed under pressure into the second chamber 24 in communication with the discharge side under the action of two check valves 21 and 22. The second chamber 24 is communicated with the interior of the first chamber 23 through two communicating passages 109 and 110, one communicating passage being preferably provided with a flow control member such as an orifice or a needle 111 for maintaining the pressure within the second chamber 24 at a predetermined value.

[0021] Housed within the casing 11 are two responsive members 112 and 113 displaced in sense to the pressure within the second chamber 24, one responsive member 112. being provided to control a valve member 114 and the other responsive member l13 to control a proportional valve 115. That is, the first responsive member 112 is secured to the forward end of a rod 116, which is in turn engaged with one end of a lever 118 supported by a shaft 117, the valve member 114 being supported on the other end of the lever 118. The valve member 114 is urged by means of a spring 122 so as to be urged against a valve seat 121 formed between an inlet passage 119 and a communicating passage 120. Accordingly, in the state where the fluid is not fed under pressure into the second chamber 24, the responsive member 112 is held at a position in which said member is moved up to its upper limit by the action of the spring 122 whereas when the pressure within the second chamber 24 increases to the first set value, the responsive member l12 is moved down against the spring 122 whereby the lever 118 is pivotally moved counterclockwise in Fig.10 so that the valve member 114 is moved away from the valve seat 121 and the gas within the inlet passage 119 flows into the communicating passage 120.

[0022] On the other hand, the second responsive member 113 is connected to the proportional valve 115 through the rod 123. This proportional valve 115 comprises a combination of a disk-like first valve 124 and an annular second valve 125, the first valve 124 being biased towards the second valve 125 by means of a spring 126, the second valve 125 being urged against a valve seat 129 disposed between a communicating passage 120 and an outlet passage 128 by means of a spring 127 retained between the second valve 125 and the first valve 124. In the illustrated embodiment, when the pressure within the second chamber 24 increases up to the aforesaid first set value, the responsive member 113 is displaced to a predetermined position to first move only the first valve 124. With this, the first valve 124 is moved away from the second valve 126 and the gas within the communicating passage 120 flows into the outlet passage 128 in a limited flow rate passing through a clearance formed therebetween. When the pressure within the second chamber 24 increases higher than the first set value, the responsive member 113 and the rod 123 are further moved down to engage with an engageable portion 123a whereby the second valve 125 is forced down and moved away from a valve seat 129, and the gas flows into the outlet passage 128 at a flow rate according to an opening degree thereof.

[0023] A regulator indicated as at 130 is of the general construction to place constant the flow rate of gas flowing from the inlet passage 119 to the outlet passage 128 through the communicating passage 120. The regulator 130 comprises a diaphragm 132 disposed between a chamber 131 connected to the inlet passage 119 through a passage not shown and the communicating passage, and a limit member 133 supported on said diaphragm 132.

[0024] Fig. 11 shows the construction of a gas combustor into which a gas flow control device including a flow control valve 140 is incorporated. In this embodiment, fuel gas is supplied, for example, to a first burner 142 for hot water supply through an on/off valve 141 constituted by the valve member 114 of the flow control device 140, the regulator 130 and the proportional valve 115. Another on/off valve 144 is provided within a system for supplying the fuel gas branched from the back of the regulator, for example, to a second burner 143 for bath. The fuel gas branched from the back of the on/off valve 141 is supplied to a pilot burner 145 provided for ignition of the first burner 142 and the second burner 143. A control circuit 146 is provided to control various elements necessary to ignite the pilot burner 145 and transmit a necessary drive signal to the gas flow control device 140, similar to that provided on a well-known gas combustor, when receiving a control input representative of the presence of and magnitude of heat demand.

[0025] The operating sequence of the gas flow control device shown in Fig. 11 is shown in Fig. 12. First, when the heat demand is present, a drive signal at a first level is transmitted from the control circuit 146 to the gas flow control valve 140. Thereby, pressure within the second chamber 24 increases up to a first value Pi to move the valve member 114 to its open position so that the combustion gas is supplied to the pilot burner 145. From this time, the ignition of the pilot burner 145 is tried only during a predetermined period of ignition trial, and if the ignition is not provided during such a period, the drive signal is immediately cut off. On the other hand, if the ignition is provided during a period of ignition trial, a drive signal at a level proportional to the magnitude of heat demand is transmitted to the gas flow control valve 140 from the control circuit 146. The pressure within the second chamber 24 is increased by the action of the device for feeding fluid under pressure which is actuated upon receipt of said drive signal, and when said pressure reaches a second value P2, the first valve 124 of the proportional valve 115 is opened to supply a minimal amount of fuel gas to the first burner 142, and then the second valve 125 is opened to a predetermined opening degree in accordance with the pressure within the second chamber 24.

[0026] Fig. 13 shows a further embodiment of the present invention in which a gas flow control device X is applied to a hot water supply device including a pilot burner 161, a main burner 162 and a heat exchanger 163. The detailed construction of the gas flow control device X is totally the same as that of Fig. 10. The gas flow control device X comprises an on/off valve 165 and a proportional valve 166, which are inserted in a mutually series relation into a pipe 164 for supplying gas to the main burner 162, an actuator for driving said valves, and a switch 168 for detection of the opening of the on/off valve 165, wherein gas is supplied to the pilot burner 161 via a pipe 169 branched from a position between the on/off valve 165 and the proportional valve 166. A control circuit 150 transmits a drive signal to the actuator 167 under the preset condition using, as the input, temperature signals from temperature detectors 151 and 152 provided on the inlet and outlet sides, respectively, of the heat exchanger 163.

[0027] Fig. 14a shows, in the flow control device shown in Fig. 10, the relationship between the level of the drive signal transmitted to the coil 18 and the pressure within the second chamber 24, and at pressure Pl, the valve 114 is open to actuate the switch 135. In case of Fig. 14b, the proportional valve 166 is actuated after a preset delay time Tb from the time at which pressure Pl is reached.

[0028] Fig. 15 shows a flow control device in accordance with a still another embodiment of the present invention, which device comprises a pressure generating portion A for generating oil pressure, a conversion portion B for converting said oil pressure into displacement, and a control portion C driven by said conversion portion B. This embodiment shows the flow control device designed so as to control the flow rate of fuel gas supplied to the combustor as in the hot water supply device.

[0029] The pressure generating portion A has an electromagnetic pump 173 composed of a coil 171 and an actuating portion 172 which extends through a center hole thereof. The electromagnetic pump 173 has a function to suck an actuating oil received within a reservoir 174 into the actuating portion 172 from a passage 175 and then to feed under pressure the oil into a pressure chamber 177 via a passage 176. This pressure chamber 177 is communicated with a second pressure chamber 180 through a passage 179 having a valve 178, said pressure chamber 180 being connected to the reservoir 174 through a passage 181 provided with an orifice having a suitable opening area. In operation of the electromagnetic pump 173, therefore, the actuating oil is fed under pressure from the reservoir 174 to the pressure chamber 177 via the passage 175, the actuating portion 172 and the passage 176 and if the valve 178 is open, reaches the pressure chamber 189 through the passage 179 and thence returned to the reservoir via the passage 181, and the oil is circulated in a route as described. Pressure according to the discharge flow rate of the electromagnetic pump 173 is generated within the pressure chambers 177 and 180 by the action of an orifice provided in the passage 181. The construction and operation of the valve 178 will be described hereinafter.

[0030] On the other hand, a bypass passage 182 is formed to connect the passage 175 on the sunction side of the electromagnetic pump 173 with the passage 176 on the discharge side thereof, and a bypass valve 183 is provided within the bypass passage 182, the bypass valve 183 being held at a closed position only during the normal operation of the electromagnetic pump 173. Thus, when the operation of the electromagnetic pump 173 is stopped after the pressure within the pressure chamber 177 has increased, the bypass valve 183 is immediately moved to its open position to thereby instantaneously release the pressure within the pressure chamber 177.

[0031] The conversion portion B provided adjacent to the pressure generating portion A has two responsive members 191 and 192. The first responsive member 191 is in contact with the interior of the pressure chamber 177 through a bellofram and secured to the forward end of an axially movable rod 193, the responsive member being urged towards the interior of the pressure chamber 177 by means of a spring 194. The second responsive member 192 is in contact with the pressure chamber 180 through a bellofram and urged towards the interior of the pressure chamber 180 by means of a spring 196 while being supported on the forward end of an axially movable rod 195. Thus, when pressure within the pressure chambers 177 and 180 increases, the responsive members 191 and 192 are moved against the springs 194 and 196, respectively, and when the pressure decreases, they are returned to their original position, whereby the pressure-displacement conversion is effected. The second responsive member 192 has a smaller pressure receiving area than that of the first responsive member 191, and hence, pressure at which the second responsive member 192 begins to be displaced is higher than that of the first responsive member 191.

[0032] The control portion C has an inlet passage 201, a communicating passage 202 and an outlet passage 203, the communicating passage 202 being preferably provided with a regulator (not shown) therein. The inlet passage 201 and communicating passage 202 are mutually communicated through a center hole of a valve seat 204, and an opening and closing valve 205 is provided urged against the valve seat 204 by the action of a spring 206. A valve rod 207 supporting the opening and closing valve 205 is in abutment with the forward end of the rod 193. The communicating passage 202 and 'outlet passage 203 are mutually communicated through a center hole of a valve seat 208, and a proportional valve 210 is provided urged against the valve seat by means of a spring 209. A valve rod 211 provided in the center of the proportional valve 210 is at one end in abutment with the forward end of the rod 196. This proportional valve 210 may be moved within the range between the totally closed position in close contact with the valve seat 208 and the totally open position in which the valve is moved away therefrom to its farthest limit to thereby proportionally control the flow rate of controlled fluid, for example, fuel gas flowing from the communicating passage 202 to the outlet passage 203.

[0033] Fig. 16 shows an example of the detailed construction of the valve 178. A housing 221 is interiorly provided with a diaphragm 223 for supporting a valve member 222 in the central portion thereof, the valve member 222 being urged against a valve seat 225 provided on the housing 221 by the action of a spring 224 retained between the housing 221 and the diaphragm 223. Thus, in this state, an inlet port 226 in communication with the pressure chamber 177 is cut off from a diaphragm chamber 227. Since the pressure on the side of the inlet port 226 exerts on the pressure receiving surface of the valve member 222 in a direction of biasing the spring 221, when said pressure reaches a preset value, the valve member 222 is moved away from the valve seat 225 against the spring 221, whereby the actuating fluid within the inlet port 226 enters the diaphragm chamber 227 and then flows into the pressure chamber 180 via the outlet port 228. Since the pressure receiving area of the diaphragm 223 is extremely larger than that of the valve member 222 under the condition that the latter is in contact with the valve seat 225, at the same time the valve member 22 is slightly moved away from the valve seat 225, the diaphragm 223 is abruptly displaced to move the valve member 222 in a direction in which the latter is moved away from the valve seat 225, which condition is maintained until pressure reaches an extremely lower level than the pressure at which the valve member 222 begins to open.

[0034] That is, when the pressure reaches the first set value during the process in which the electromagnetic pump 173 is actuated to increase the pressure within the pressure chamber 177, the first responsive member 191 is first displaced to move the opening and closing valve 205 to its open position. Thereby, the fuel gas flows from the inlet passage 201 to the communicating passage 202 and then flows into the pilot burner for ignition thereof. However, in this state, since the valve 178 is closed, the pressure within the second pressure chamber 180 is low. Next, when the pressure within the pressure chamber 177 further increases up to the pressure for opening the valve 178, the valve member 222 is held at this position after it has moved abruptly to its open position as previously described, and therefore, the actuating fluid flows into the pressure chamber 180 through the passages 176 and 179 and is returned to the reservoir 174 via the passage 181 to thereby develope pressure substantially equal to that within the pressure chamber 177. Accordingly, the responsive member 192 is displaced according to the pressure within the pressure chamber 180 to proportionally actuate the proportional valve 210 so that the flow rate of the fuel gas supplied from the communicating passage 202 to the main burner via the outlet passage 203 is proportionally controlled. Conversely, during the process in which pressure within the pressure chamber 177 decreases, the valve 178 remains opened until said pressure reaches a substantially zero.

[0035] As described above, in accordance with the present invention, two valves provided in a main flow passage in a mutually series relation can be operated to be opened and closed by means of a single valve drive device including an electromagnetic pump, which arrangement is simple in piping and compact in the entire structure as compared with the case where two independent electromagnetic valves are provided. Furthermore, mechanical delaying means including a dash pot provided in the responsive member can provide a necessary differential with the operating timing of two valves and therefore is suitable for the operation of the valve when the main burner is ignited in a given time after the ignition of the pilot burner, for example.

[0036] In addition, in case a plurality of communicating passages are provided in a mutually parallel relation between the first and second chambers, even if either of the communicating passages is lodged with dust or the like, the second chamber never remains kept at high pressure even after stoppage of the electromagnetic pump and there occurs no inconvenience in that the valves or the like remain opened.

[0037] Moreover, in accordance with the present invention, a plurality of valve means can be opened and closed by means of a single valve drive device at the desired time and in the predetermined order. Thus, in case that the control valve is applied to control the gas in the combustor shown in Fig. 1, high reliability may be obtained by the positive operation and the entire structure may be designed compactly.

[0038] Furthermore, in accordance with the present invention, a plurality of valve means can be controlled by means of a single electromagnetic pressure feed device, and each of the valve devices can be on/off controlled or proportionally controlled. Accordingly, it becomes easy to control the flow rate of fuel gas of the gas combustor, and the positiveness of operation may be enhanced.

[0039] Besides, in the present invention, it is designed so that the on/off valve and proportional valve inserted in series in the gas flow passage are driven by means of a single actuator, and the switch is used to detect if the on/off valve is open. Thus, the stabilized control may be performed even if the operating regions of the on/off valve and proportional valve are brought into closer.

[0040] Finally, in accordance with the present invention, in an arrangement wherein the first responsive member and the second responsive member actuated at a higher pressure than that of the first responsive member are actuated under the pressure from an electromagnetic pump common thereto, a valve, which is open at a higher pressure than the actuating pressure of the first responsive member but is.not closed until the pressure decreases to a level lower than said pressure, is inserted into a passage of the actuating oil for exerting the pressure, which exerts on the first responsive member, on the second responsive member, and therefore, even if the lower limit value in the range of pressure at which the second responsive member is actuated proportionally is set to the same value as the actuating pressure of the first responsive member or to the value close thereto, there occurs no inconvenience in that the second responsive member is displaced prior to the first responsive member. For this reason, it is possible to increase the range of pressure at which the second responsive member is actuated proportionally, thus realizing an actuator which is small in size and excellent in controllability.

Claims

1. A pump drive valve device comprising a first chamber and a second chamber in communication with a suction side and a discharge side, respectively, of an electromagnetic pump, a communicating passage to communicate said first and second chambers with each other, a flow control member provided on said communicating passage to maintain pressure within said second chamber at a predetermined value, a responsive member displaced in sense to the pressure within said second chamber, and a first valve device actuated to be opened and closed by displacement of said responsive member, wherein said first valve device is maintained at its open position by maintaining the pressure within said second chamber at a predetermined value when said electromagnetic pump is actuated.

2. The pump drive valve device according to Claim 1 further comprising connecting means for operatively connecting said responsive member to said first valve device, and a second valve device connected to said connecting means through a lever and opened and closed by displacement of said responsive member.

3. A pump drive valve device comprising a single valve drive device for supplying suction fluid to a pressure chamber through a pressure electromagnetic pump to maintain the interior thereof at a-predetermined pressure, a responsive member displaced in response to pressure within said pressure chamber, and a plurality of valve means actuated to be opened and closed by displacement of said responsive member, wherein the opening of each of said valve means is adjusted by varying the pressure within said pressure chamber by said pressure electromagnetic pump.

4. A pump drive valve device comprising a first chamber and a second chamber in communication with a suction side and a discharge side, respectively, of a single electromagnetic pump, a communicating passage to communicate said first and second chambers with each other, a flow control member provided on said communicating passage to maintain pressure within said second chamber at a predetermined value, a plurality of responsive members displaced in sense to pressure within said second chamber, and a plurality of valve means actuated to be opened and closed by displacement of each of said responsive members, wherein each of said valve means is maintained at its open position by maintaining the pressure within said second chamber at a predetermined value when said electromagnetic pump is actuated.

5. The pump drive valve device according to Claim 4 wherein at least one of said responsive members is connected to a mechanical delay device for controlling the operating time for opening and closing the valve means actuated to be opened and closed by displacement of said responsive member, and each of said valve means is sequentially operated in a predetermined order from the time said electromagnetic pump is actuated.

6. A pump drive valve device comprising a single valve drive device for supplying suction fluid to a pressure chamber through a pressure electromagnetic . pump to maintain the interior thereof at a predetermined pressure, a first and second responsive members displaced in response to pressure within said pressure chamber, a first valve means actuated to be opened and closed by displacement of the first responsive member, and a second valve means actuated to be opened and closed by displacement of the second responsive member, wherein the opening degree of the first and second valve means is sequentially adjusted by varying pressure within said pressure chamber in said electromagnetic pump.

7. The pump drive valve device according to Claim 4, wherein said second valve means has a mechanical delay device.

8. The pump drive valve device according to Claim 4, wherein said first and second valve means are a pilot gas valve and a main gas valve, respectively, so that when pressure within said pressure chamber is a first .pressure, only said pilot gas valve is open, and when said pressure chamber is a second pressure, both the pilot gas valve and main gas valve are open.

9. A pump drive valve device comprising a single valve drive device for supplying suction fluid to a pressure chamber through a pressure electromagnetic pump to maintain the interior thereof at a predetermined pressure, a first and second responsive members displaced in response to the pressure within said pressure chamber, a valve means for controlling a main valve and a pilot gas valve by displacement of said first responsive member, and a main gas valve means actuated to be opened and closed by displacement of said second responsive member, wherein the opening of said main valve, said pilot gas valve and said main gas valve by varying pressure within said pressure chamber in said electromagnetic pump.

10. A pump drive valve device comprising a single valve drive device for supplying suction fluid to a pressure chamber through a pressure electromagnetic pump to maintain the interior thereof at a predetermined pressure, a first and second responsive members displaced in response to pressure within said pressure chamber, a first valve means actuated to be opened and closed by displacement of the first responsive member, and a second valve means proportionally actuated by displacement of the second responsive member, wherein the opening degree of said first and second valve means is sequentially adjusted by varying pressure within said pressure chamber in said electromagnetic pump.

11. The pump drive valve device according to Claim 10, wherein said first and second valve means are a gas safety valve and a main gas proportional valve, respectively, so that when pressure within said pressure chamber is a first pressure, only said gas safety valve is open, and when said pressure chamber is a second pressure, both the gas safety valve and main gas proportional valve are open.

12. The pump drive valve device according to Claim 11, wherein said proportional valve comprises a first valve which is open when pressure within said pressure chamber is below a preset value to secure a minimum flow rate, and a second valve the opening degree of which is varied in proportional to the pressure when such pressure is above the preset value.

13. The pump drive valve device according to Claim 12, wherein said valve device further comprises switch means for detecting the state that said on/off valve is open, and a control circuit for performing said proportional control only when said switch means has detected that said on/off valve is open.

14. The pump drive valve device according to Claim 13, wherein said control circuit comprises a delay means for actuating said proportional valve after a lapse of predetermined set time after said switch has detected that said on/off valve is open.

Drawing