Controlled current solenoid driver circuit

Claim 2

A fluid dispensing control for controlling the dispensing of heated fluid, comprising: a valve having a movable fluid control valving element for controlling the flow of fluid therethrough in dependence upon the position of said valving element; a solenoid having an electrical coil and a movable armature connected to said valving element for selectively positioning said valve element to control the flow of fluid through said valve, said coil being in heat transfer relationship to heated fluid flowing through said valve, and a solenoid driver circuit including (a) means for sensing the level of current flowing through said solenoid and providing an output signal correlated thereto, (b) power supply means, (c) means for generating first and second reference signals correlated to predetermined peak and hold-in currents in said solenoid, respectively, (d) means for comparing: i) said first reference signal and said sensing means output signal and generating in response thereto a solenoid peak current control signal when said solenoid current reaches said peak current, and ii) said second reference signal and said- sensing means output signal and generating in response thereto a solenoid hold-in current control signal correlated to the difference therebetween, and (e) solenoid current regulating means interconnecting said power supply means and said solenoid, said regulating means being sequentially responsive to, i) an externally applied turn-on control signal, ii) said peak current control signal, iii) said hold-in current control signal, and iv) an externally applied turn-off control signal, for initially energizing said solenoid to raise the current level therein until said peak solenoid current is reached, whereupon said solenoid current is reduced and maintained at a hold-in current level until said externally generated turn-off control signal is applied.

Claim 3

The fluid dispensing control of Claim 1 in which the comparing means and the solenoid current regulating means comprise: a comparator and amplifier circuit having a first input coupled to the current sensing means output and a second input, which is coupled to the first reference signal before the peak solenoid current is reached and which is coupled to the second reference signal after the peak solenoid current is reached; means for coupling a first voltage across the solenoid in response to the externally applied turn-on control signal and for removing the first voltage from the solenoid in response to said solenoid peak current control signal; and means for controlling the level of a second voltage coupled across the solenoid, after the removal of the first voltage, in response to said solenoid hold-in current control signal, the comparator and amplifier circuit having a first output coupled to the first voltage coupling means and a second output coupled to the second voltage controlling means, the comparator and amplifier circuit being operable to compare its inputs to produce at its first output, when the first voltage is coupled across the solenoid, the solenoid peak current control signal, and to produce at its second output, when the controlled level of the second voltage is coupled across the solenoid, the solenoid hold-in current control signal.

Claim 4

The fluid dispensing control of claim 2 which further comprises a latch circuit, which has an input coupled to the first output of the comparator and amplifier circuit to receive the solenoid peak current control signal therefrom, and which has an output coupled to the first voltage coupling means for coupling said solenoid peak current control signal to the first voltage coupling means, whereby the first voltage coupling means removes the first voltage from the solenoid, the latch circuit being operable to maintain the first voltage coupling means in this condition until the latch circuit is reset.

Claim 5

The fluid dispensing control of Claim 3 in which the latch circuit further includes a controlled switch which is responsive to the solenoid peak current control signal coupled to the input of the latch circuit to switch the reference generating means from generating the peak current reference signal to generating the hold-in current reference signal.

Claim 6

The fluid dispensing control of Claim 4 in which the reference generating means produces a hold-in current reference signal which effects a gradual transition from the peak current reference value to a hold-in current reference value in response to operation of the switch in the latch circuit.

Claim 7

The fluid dispensing control of claim 5 in which the reference generating means is responsive to said externally applied turn-off control signal to remove the hold-in current reference signal from the comparing means, which is responsive thereto to remove the hold-in current control signal from the second voltage controlling means to effect the removal of the controlled level of the second voltage from the solenoid.

Claim 8

The fluid dispensing control of claim 6 which further comprises a snubber network coupled across the solenoid which includvs a zener diode connected in series with an oppositely poled diode.

Claim 9

The fluid dispensing control of claim 1 which further comprises a snubber circuit coupled across the solenoid and operable to limit the amplitude of an induced reverse voltage across the solenoid each time said externally generated turn-off control signal is applied, whereby a portion of the magnetic energy stored in the solenoid, when each said turn-off control signal is applied, is dissipated in the snubber circuit.

Claim 10

A fluid dispensing control for controlling the dispensing of heated fluid, comprising: a valve having a movable fluid control valving element for controlling the flow of fluid therethrough in dependence upon the position of said valving element; a solenoid having an electrical coil and a movable armature connected to said valving element for selectively positioning said valve element to control the flow or fluid through said valve, said coil being in heat transfer relationship to heated fluid flowing through said valve, and a solenoid driver circuit including (a) means for sensing the level of current flowing through said solenoid and providing an output signal correlated thereto, (b) a source of electrical power providing a solenoid-energizing voltage, (c) means for connecting said source of electrical power to said solenoid to establish a current in said solenoid, (d) controlling means connected to said connecting means for controlling said solenoid current such that it reaches a first predetermined value and is thereafter changed to a second predetermined value, lesser in magnitude, in a preselected manner.

Claim 11

A fluid dispensing control for controlling the dispensing of heated fluid, comprising: a valve having a movable fluid control valving element for controlling the flow of fluid therethrough in dependence upon the position of said valving element; a solenoid having an electrical coil and a movable armature connected to said valving element for selectively positioning said valve element to control the flow or fluid through said valve, said coil being in heat transfer relationship to heated fluid flowing through said valve, and a solenoid driver circuit including (a) means for sensing the level of current flowing through said solenoid and providing an output signal correlated thereto, (b) a source of electrical power providing a solenoid-energizing voltage, (c) means for connecting said source of electrical power to said solenoid to establish a current in said solenoid, (d) controlling means connected to said connecting means for controlling said solenoid current such that it reaches a first predetermined value and is thereafter changed to a second predetermined value, lesser in magnitude, in a preselected manner.

Claim 12

The fluid dispensing control of claim 9 wherein said current controlling means comprises: sensing means for sensing the current flowing in said solenoid and generating an output signal, reflective of said current; and regulating means for regulating said voltage from said power source applied to said solenoid in response to said output signal such that solenoid current rises in magnitude to said first predetermined value and thereafter is reduced in magnitude to said second predetermined value in said predetermined manner.

Claim 13

The fluid dispensing control of claim 10 which further comprises a snubber circuit coupled across the solenoid and operable to limit the amplitude of induced reverse voltages across the solenoid when said source of electrical power is disconnected from the solenoid, whereby a portion of the magnetic energy stored in the solenoid is dissipated in the snubber circuit.

Claim 14

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid in response to a solenoid peak current control signal; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for comparing the sensed current output of the means (b) to a peak current reference value, when the first voltage is coupled across the solenoid, to produce a solenoid peak current control signal coupled to the means (a) when the sensed current reaches the peak current reference value; and (d) means for applying a second voltage to the solenoid after the removal of the first voltage.

Claim 15

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid in response to a solenoid peak current control signal; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for comparing the sensed current output of the means (b) to a peak current reference value, when the first voltage is coupled across the solenoid, to produce a solenoid peak current control signal coupled to the means (a) when the sensed current reaches the peak current reference value; and (d) means for applying a second voltage to the solenoid after the removal of the first voltage.

Claim 16

The solenoid driver circuit of claim 12 in which the means (d) includes means for controlling the level of the second voltage so that it gradually falls from a first value to a lower hold-in voltage value after a transition interval.

Claim 17

The solenoid driver circuit of claim 12 in which the means (c) comprises a comparator circuit having a first input coupled to the peak current reference value and having a second input coupled to the sensed current output of the means (b), the comparator circuit being operable to compare the signals at the two inputs to produce a solenoid peak current control signal at an output when the input signals are equal.

Claim 18

The solenoid driver circuit of claim 14 which further includes a latch circuit coupled between the output of the comparator circuit and the means (a) for coupling the solenoid peak current control signal to the means (a) until the latch is reset.

Claim 19

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid in response to a solenoid peak current control signal; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for comparing the sensed current output of the means (b) to a peak current reference value, when the first voltage is coupled across the solenoid, to produce a solenoid peak current control signal coupled to the means (a) when the sensed current reaches the peak current reference value; and (d) means for controlling the current through the solenoid after the removal of the first voltage from the solenoid.

Claim 20

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid in response to a solenoid peak current control signal; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for comparing the sensed current output of the means (b) to a peak current reference value, when the first voltage is coupled across the solenoid, to produce a solenoid peak current control signal coupled to the means (a) when the sensed current reaches the peak current reference value; and (d) means for controlling the current through the solenoid after the removal of the first voltage from the solenoid.

Claim 21

1 7 . The solenoid driver circuit of claim 16 in which the means (d) includes means for controlling the solenoid current to make a gradual transition from the level of current in the solenoid when the first voltage is removed to a lower, substantially constant, hold-in current.

Claim 22

The solenoid driver circuit of claim 17 in which the means (d) controls the level of a second voltage applied to the solenoid after the removal of the first voltage in response to a solenoid hold-in current control signal and further comprising means (e) for comparing the sensed current output of the means (b) to a hold-in current reference signal while the second voltage is coupled to the solenoid to produce the solenoid hold-in current control signal which is coupled to the means (d), and means (f) for producing the hold-in current reference signal which comprises a resistor-capacitor parallel combination which is connected in series with a resistance, the series combination being coupled across a d-c supply at the time that the first voltage is removed from the solenoid, the hold-in current reference signal output being taken at the connection between the resistor-capacitor parallel network and the series resistance.

Claim 23

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for controlling the level of a second voltage coupled across the solenoid after the removal of the first voltage in response to a solenoid hold-in current control signal; and (d) means for comparing the sensed current output of the means (b) to a hold-in current reference signal, when the second voltage is applied to the solenoid, to produce a solenoid hold-in current control signal coupled to the means (c).

Claim 24

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal and for removing the first voltage from the solenoid; (b) means for sensing the current flowing in the solenoid to produce a sensed current output; (c) means for controlling the level of a second voltage coupled across the solenoid after the removal of the first voltage in response to a solenoid hold-in current control signal; and (d) means for comparing the sensed current output of the means (b) to a hold-in current reference signal, when the second voltage is applied to the solenoid, to produce a solenoid hold-in current control signal coupled to the means (c).

Claim 25

The solenoid driver circuit of claim 19 in which the means (d) comprises a comparator and amplifier circuit having a first input coupled to the sensed current output of the means (b) and having a second input coupled to a hold-in current reference signal when the controlled level of the second voltage is applied to the solenoid, and having an output coupled to the means (c), the comparator and amplifier circuit being operable to compare the sensed solenoid current and the hold-in current reference signal to produce at its output the solenoid hold-in current control signal.

Claim 26

The solenoid driver circuit of claim 20 which further comprises means (e) for producing a hold-in current reference signal coupled to the second input of the comparator and amplifier circuit, the means (e) being responsive to a turn-off control signal to remove the hold in current reference signal from the comparator and amplifier circuit, the comparator and amplifier circuit being responsive to the removal of the hold-in current reference signal to remove the solenoid hold-in current control signal from the means (c), whereby the second voltage is removed from the solenoid.

Claim 27

The solenoid driver circuit of claim 21 in which the means (e) produces a hold-in current reference signal which effects a gradual transition from a first current reference value to a hold-in current reference value.

Claim 28

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for sensing the current flowing in the solenoid to produce a sensed current output; (b) means for controlling the level of a voltage coupled across the solenoid in response to a solenoid hold in current control signal, and (c) means for comparing the sensed current output of the means (a) to a hold-in current reference signal to produce a hold-in current control signal which is coupled -to the means (b).

Claim 29

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operable to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for sensing the current flowing in the solenoid to produce a sensed current output; (b) means for controlling the level of a voltage coupled across the solenoid in response to a solenoid hold in current control signal, and (c) means for comparing the sensed current output of the means (a) to a hold-in current reference signal to produce a hold-in current control signal which is coupled -to the means (b).

Claim 30

The solenoid driver circuit of claim 23 in which the means (c) comprises a comparator and amplifier circuit having a first input coupled to the sensed current output of the means (a) and a second input coupled to a hold-in current reference signal, and having an output coupled to the means (b), the comparator and amplifier circuit being operable to compare the sensed current output of the means (a) and the hold-in current reference signal to produce at its output a solenoid hold-in current control signal.

Claim 31

The solenoid driver circuit of claim 24 which further comprises means (d) for producing a hold-in current reference signal coupled to the means (c), the means (d) being responsive to a turn-off control signal to remove the hold-in current reference signal from the means (c), the means (c) being responsive to the removal of the hold-in current reference signal to remove the solenoid hold-in current control signal from the means (b), whereby the voltage is removed from the solenoid.

Claim 32

The solenoid driver circuit of claim 23 in which the means (d) further includes means for providing a hold-in current reference signal which has a first value corresponding to a relatively high solenoid current and a second value corresponding to a relatively low solenoid current and a gradual transition interval in which the hold in current reference signal decreases gradually from the first value to the second value.

Claim 33

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operatble to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal; (b) means for changing the voltage applied to the solenoid when the solenoid current reaches a selected peak current level; and (c) means for controlling the voltage applied to the solenoid after the peak current is reached in order to control the current through the solenoid until a turn-off control signal is externally applied.

Claim 34

In a solenoid-operated heated-fluid dispensing arrangement having a valve which is operatble to dispense a heated fluid and a solenoid energizable to operate the valve, an improved driver circuit to energize the solenoid in response to externally applied turn-on and turn-off control signals, comprising: (a) means for coupling a first voltage across the solenoid in response to an externally applied turn-on control signal; (b) means for changing the voltage applied to the solenoid when the solenoid current reaches a selected peak current level; and (c) means for controlling the voltage applied to the solenoid after the peak current is reached in order to control the current through the solenoid until a turn-off control signal is externally applied.

Claim 37

The method fo claim 28 which further includes, prior to the step (d), the additional step of controlling the solenoid current to gradually decrease from the preselected peak value to a hold-in current value.

Claim 38

The method of claim 29 which further includes, after the step (d), the additional step of: permitting the current in the solenoid to decay to zero in response to'an externally supplied turn-off signal.

Claim 39

The solenoid driver circuit of either of claims 15 or 18 in which the means (a) comprises an electronic switch coupled in series between an end of the solenoid and a voltage source.

Claim 40

The solenoid driver circuit of claim 22 in which the means for controlling the level of a second voltage is a transistor coupled between an end of the solenoid and a voltage source.

Claim 41

The solenoid driver circuit of any of claims 15, 18 or 22 in which the means (b) comprises a current sensing resistance connected in series with the solenoid.

Claim 42

The solenoid driver circuit of claim 33 in which a snubber circuit is coupled across the solenoid.

Claim 43

The solenoid driver circuit of claim 34 in which the snubber circuit comprises a zener diode connected in series with an oppositely poled diode.

Claim 44

The solenoid driver circuit of claim 34 in which the snubber circuit is connected in parallel with the series connected solenoid and current sensing resistance.

Claim 45

A fluid dispensing control for controlling the dispensing of heated fluid, comprising: a valve having a movable fluid control valving element for controlling the flow of fluid therethrough in dependence upon the position of said valving element; a solenoid having an electrical coil and a movable armature connected to said valving element for selectively positioning said valve element to control the flow of fluid through said valve, said coil being in heat transfer relationship to heated fluid flowing through said valve, and a solenoid driver circuit including (a) means for generating turn-on and turn-off control signals, (b) means for generating first and second voltages, (c) application means for applying said first voltage to the solenoid in response to said turn-on control signal, (d) means for conductively connecting said application means to said turn-on control signal generating means and to said first voltage generating means, (e) means for sensing the current flowing in said solenoid to produce a sensed current output signal, (f) terminating means for terminating the application of said first voltage to said solenoid, . (g) means for conductively connecting the terminating means to the sensing means such that said terminating means removes said first voltage from said solenoid in response to said sensed current output signal reflecting that the current flowing in said solenoid has reached a first predetermined value, ( h ) means for applying said second voltage to said solenoid, (i) means for conductively connecting said application means of said second voltage to said terminating means such that said second voltage is not applied to said solenoid until after the termination of said first voltage, (j) means for regulating said second voltage applied to said solenoid, (k) means for conductively connecting said sensed output signal to said regulating means such that the current in said solenoid is reduced from said first predetermined value to a second predetermined value, lesser in magnitude, in a predetermined manner, (1) means for terminating the application of said second voltage to said solenoid, (m) means for conductively connecting said second voltage terminating means to said turn-off control signal generating means, such that said second voltage is removed from said solenoid in response to said turn-off control signal, (n) means for dissipating the current in said solenoid, and (o) means for conductively connecting said dissipating means to said solenoid such that said current in said solenoid is dissipated after the termination of said second voltage by the second voltage terminating means.

Claim 46

A fluid dispensing control for controlling the dispensing of heated fluid, comprising: a valve having a movable fluid control valving element for controlling the flow of fluid therethrough in dependence upon the position of said valving element; a solenoid having an electrical coil and a movable armature connected to said valving element for selectively positioning said valve element to control the flow of fluid through said valve, said coil being in heat transfer relationship to heated fluid flowing through said valve, and a solenoid driver circuit including (a) means for generating turn-on and turn-off control signals, (b) means for generating first and second voltages, (c) application means for applying said first voltage to the solenoid in response to said turn-on control signal, (d) means for conductively connecting said application means to said turn-on control signal generating means and to said first voltage generating means, (e) means for sensing the current flowing in said solenoid to produce a sensed current output signal, (f) terminating means for terminating the application of said first voltage to said solenoid, . (g) means for conductively connecting the terminating means to the sensing means such that said terminating means removes said first voltage from said solenoid in response to said sensed current output signal reflecting that the current flowing in said solenoid has reached a first predetermined value, ( h ) means for applying said second voltage to said solenoid, (i) means for conductively connecting said application means of said second voltage to said terminating means such that said second voltage is not applied to said solenoid until after the termination of said first voltage, (j) means for regulating said second voltage applied to said solenoid, (k) means for conductively connecting said sensed output signal to said regulating means such that the current in said solenoid is reduced from said first predetermined value to a second predetermined value, lesser in magnitude, in a predetermined manner, (1) means for terminating the application of said second voltage to said solenoid, (m) means for conductively connecting said second voltage terminating means to said turn-off control signal generating means, such that said second voltage is removed from said solenoid in response to said turn-off control signal, (n) means for dissipating the current in said solenoid, and (o) means for conductively connecting said dissipating means to said solenoid such that said current in said solenoid is dissipated after the termination of said second voltage by the second voltage terminating means.

Claim 47

The fluid dispensing control of claim 3 7 wherein said regulating means comprises:- means for generating a preselected changing reference voltage; comparison means; means for conductively connecting said comparison means to said reference voltage generating means and said sensed current output signal from the current sensing means; controlling means, conductively connected to said second voltage application means, for controlling the amount of said second voltage applied to said solenoid by said second voltage application means; and generating means conductively connected and interposed between said comparison means and said second voltage control means, for providing a control signal to said control means in response to said comparison means.

Claim 48

The fluid dispensing control of claim 38 wherein said comparison means further comprises means for controlling said terminating means.

Claim 49

The fluid dispensing control of claim 39 wherein said means for generating a preselected reference voltage comprises: means for generating a third voltage; voltage divider means conductively connected to said third voltage generating means, for dividing said voltage between a first and second resistor; a capacitor connected in parallel with the second resistor; means for conductively connecting said comparison means to said voltage divider, such that said comparison means receives a divided voltage; and voltage divider control means, interposed between and conductively connected to said voltage divider means and said comparison means such that said voltage divider means is turned on in response to said comparison means identifying as identical the voltage across the second resistor and the sensed current output signal of said current sensing means.