JPS60188731A - Combustion control device - Google Patents

Abstract

PURPOSE:To eliminate generation of hunting by a method wherein control of decreasing or increasing of the supplying amount of fuel is prohibited for a given time after generation of one transient response even when either one of overshoot transient response or undershoot transient response is generated and the other transient response is detected. CONSTITUTION:The outputs E, F, G, H, of respective comparators A3, A4, which are detecting overshoot and undershoot, and respective comparators A7, A8, as changing speed deciding means, are being inputted in a hunting preventing circuit 5 while the output V of PID control circuit 1 is controlled so as to maintain it in one of predetermined amounts VL, VH, corresponding respectively, in case overshoot and undershoot are detected. In this case, the hunting preventing circuit 5 starts a timer 5a and prohibits the output generation thereof so that the other output O2 will never become ''L'' level by the detection of undershoot until the given time, corresponding to one period of hunting generated in case the hunting preventing circuit 5 is not equipped.

Description

[Detailed description of the invention]

The present invention provides a combustion control device for proportionally controlling the combustion of combustion equipment, specifically a 2i combustion control device for maintaining hot water temperature at a set temperature.
The present invention relates to a combustion control device including a control means including at least an integrating means for proportionally controlling a fuel supply amount based on a comparison result with a humidity detection degree. Conventionally, in this type of combustion control device, proportional control means that can automatically adjust the amount of fuel supply, that is, the amount of heat supplied, in response to the deviation between the set temperature and the detected temperature has been increasingly adopted from the viewpoint of energy conservation. ing. The above-mentioned proportional control means can freely adjust the hot water temperature and can perform stable temperature control without supplying unnecessary fuel. If this occurs, a transient response such as overshoot or undershoot will occur in the control, and the temperature will fluctuate significantly relative to the set temperature, resulting in the output of C, which requires a means to prevent this transient response. . As a means to prevent this divine transient response, for example, Japanese Patent Application Laid-Open No. 57-81722-Li (Japanese Patent Application No. 55-105710
No.) There is a combustion control device disclosed in the publication, but this means is not sufficient and has the following disadvantages. That is, as shown in FIG. 4, the subsource ν'A', 8:(V
cc) is resistor-divided reference voltage (Vl)') and 771
The deviation from the output 'F1 pressure (Va) of the thermistor (Rγ) as a means for determining
)K to determine the opening degree of the proportional valve (2') that adjusts the fuel supply (1) (configured to control eight drive currents, and with respect to the reference voltage (vb') An over-V! , the input level of the integral 91 (AI') is shifted depending on the output of this overshoot detection circuit (c, PID).
By forcibly lowering the control cycle (1 control amount force (V'), the proportional valves (two) are returned to the minimum opening degree that maintains combustion. However, the overshoe) m output 1 m path (four are configured to detect the occurrence of overshoot based only on the deviation of the detected voltage (Va') from the amount of temperature change, that is, the reference voltage (■♂), and the integrator (Temporarily -tJ by shifting the AI input)
Since the PID control circuit operates to reduce one output (V), it has the following drawbacks. There was a drawback that the return of the integrator to the active state after the shoot occurred was delayed, and open neat and homogeneous undershoots occurred newly, and it took time for the temperature to stabilize. In order to solve this problem, the applicant has already proposed a combustion control device equipped with a means for preventing transient response by checking both the temperature deviation and the rate of temperature change. is not sufficient to effectively prevent both transients;
There was room for improvement. In other words, each transient response of overshoot and undershoot is detected and the output of the control device is adjusted to a corresponding predetermined M'K.
Although it is configured to make m n. For example, when an overshoot occurs, the output drops rapidly, causing the same operation as when an undershoot occurs, causing the control to easily fall into a hunting state. The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide combustion control with a control means that does not cause hunting in response to sudden load changes and has less transient response of overshoot or undershoot. The goal is to provide equipment. In order to achieve this on a regular basis, the combustion control device according to the present invention has the following features:
Transient response detection means for detecting whether a transient response, overshoot or undershoot, has occurred in temperature control, and when a transient response is detected by the transient response detection means, the output of the control means regardless of the detected temperature; The operation of the control means is regulated to maintain one of the predetermined values set in advance in response to overshoot and undershoot, respectively, and once one of the transient responses is detected, The present invention is characterized in that hunting prevention means is provided for inhibiting control to maintain the output at the other predetermined value even if the other transient response is detected until a certain period of time has elapsed. The above ()ij configuration will be explained below based on the block diagram shown in FIG. Figure 1 is a block diagram of a combustion control device for adjusting the hot water temperature by proportionally controlling the amount of burnt water, such as in an Differentiator (A1) and an integrator (
The PID control means (11) equipped with aluminum is configured to proportionally control the opening degree of the proportional valve (2) as means for adjusting the fuel supply mechanism.Furthermore, the detected temperature (

) and the set temperature (t), the detected temperature b) is at least a predetermined ratio to the set temperature (t), that is, the deviation (Δt) is a preset predetermined value (α1)
If the above conditions are met, and the rate of change (vertical) of the detected temperature (tl) is greater than or equal to a predetermined value (ag), it is detected that a transient response has occurred to the altitude change, and the PID control means fxl
A transient response detection means (4) for generating (N) for controlling the fuel supply tf to decrease or increase by temporarily stopping the operation of the fuel supply tf; The operation of the means (1) is regulated so that the output (V) of the means (1) is temporarily held at one of predetermined values (ML) and (VH), which are preset in response to overshoot and undershoot, respectively. With,
After the excessive leakage response of either the overshoot or undershoot is extracted, a certain period of time (
Hunting prevention means (6) may be provided to prevent the control for maintaining the output (v) at the other of the predetermined values (VL) and (Vll) until the time period τ) elapses even if the other transient response is detected. be. The transient response detection means (4) includes a detection temperature (
tl and the set temperature (deviation CΔt of t) are set to the predetermined value (
α1) Overshoot judgment temperature set high (
An overshoot detection means (4a) for detecting whether 4) or tongue is above t') and an undershoot by setting a predetermined value jfI (α1) lower than the set temperature (t).
Temperature deviation detection means (6) consisting of undershoot detection means (4b) for detecting whether it is less than 1 degree (tO), detection crystal J!j (change rate of tl (8))
Differential value construction means (4c) for detecting, and 1lt
A comparator (as a rate of change determining means) for determining whether the differential value (AG) is greater than or equal to a predetermined value dα2) set as the upper limit (to) 2) and lower limit (-ag) of the rate of change. 4d) and (4e), and is configured to output a transient response detection signal corresponding to the temperature law difference (Δt), its rate of change (f), and its direction. When the hunting prevention means (5) is configured as an FA, one of the timers (5a, 5b) is activated based on the transient response detection signal output from the transient response detection means (4), and this timer (5a) is activated. , 5b) is started, the other timer (5b
, 5a) are provided. Then, when overshoot or undershoot occurs, the hunting prevention] hite s(6+) output (
A resistor (RL) is connected to the input of the control means (+I) in order to forcibly maintain the output (OI), Cot) K and therefore #+J output) at one of the corresponding predetermined values (VL) and (VH), respectively. , CRn). In other words, when overshoot occurs, one output (0,)K of the hunting prevention means (5) causes
A predetermined voltage corresponding to the resistor (RH) K is determined by a differentiator (AI).
) is added to the input of the controller ff (II) to lower the output (V) of the controller ff (II) to the predetermined value (VL) K, which is the lower limit value for maintaining combustion, and the timer (5a) is added to the input of the controller ff (II) for a certain period of time (τ ) until the time elapses, the output of the other force (Og) of the hunting prevention means (5) is prohibited, and the PI
This is to prevent hunting in the operation of the D control means (1). Similarly, when undershoot occurs, the other output (02
), a predetermined voltage corresponding to the resistor (phase) K is added to the input of the integrator (A2), and the output (V
In addition to raising l to the predetermined value (VH), which is the upper limit value, the timer (513) controls the time (
τ), the output (01) of the hunting prevention means (5) is stopped. The above-mentioned number of configurations has achieved the excellent effect as described below.In other words, even if either overshoot or undershoot transient response occurs due to sudden fluctuations in the hot spring temperature, the amount of fluctuation and the change in Regardless of the speed, the fuel supply amount is automatically decreased or increased in accordance with the direction, and for a certain period of time after one transient response occurs, even if the other transient response is detected. Since control of the decrease or increase in the amount is prohibited, it is possible to minimize the transient response without causing hunting.Specific embodiments of the present invention will be described below with reference to the drawings. As shown in Figure 2, there is a trap, a resistor (R+) between the power supply (Vcc) and the ground point, and a thermistor (RT) as a temperature detection means.
), a correction resistor (R8), and a variable resistor (VR) as a temperature setting means are connected in series, and a power supply (Vc
c) and the ground point, there is a resistance (Rg). (R@), (R4), (Rs) and the adjustment resistor (VR,) are connected in series.
The detection voltage (v8) obtained from the connection point between R+) and thermistor (RT) is passed through a buffer circuit (All) to a PID in which a differentiator (AI) and an integrator (A) are connected in series.
Overshoot/detection means (4a) that inputs to the control circuit (1) and constitutes the temperature deviation detection means (6)
Both the comparator (A8) and the undershoot detection means (4b) are manually operated. - horn, the resistance of the horn (R2), (
Rs), (R4) 5 (R6) connection points (C1,
(Bl, each reference voltage (VC) obtained from (D+),
(vb), (vd) are husband 4 PID control 1 + il path 11
)> and both comparators (As) and (Ag) are input as reference voltages. (Va)
By comparing the set temperature Cto), the temperature (to') at which the difference (8 tons) of the detected temperature (tl) increases or decreases by a predetermined value (crystal) with respect to the set temperature (Lo), (to
It operates to output "L" level outputs (E) and (F) when the voltage rises or falls by more than I). Also, IJ: written as J - Minuta CRT) and Kaga resistor (VR).
) The detected "suitable pressure (VS) obtained from the connection point (Sl) is a means of detecting the velocity of temperature change -j, that is, the differential value (depression). (A6)
The differentiator (4L) is manually operated. Then C1 this minute Ls'ax < /J s /7) Il, L -1'
l ru=)fy -6il um' freezing degree determination means (
4d), comparator (Ay) as (4e),
Three resistances (R@), (Ry) by (As)
, (Rg) and the adjustment resistor (■2), the power supply (
By comparing it with a predetermined value (±α2), which is the reference for the rate of change, obtained by resistor-dividing Vcc), the differential value of the 'L' level corresponding to the direction of temperature change is determined.
(G+, (Hl). Each comparator (A, a), (AI) detects the overshoot F and undershoot, and each comparator l< rater (
A7), (A8) outputs (E), (F),
(Gl, ()υ) is input to the hunting prevention circuit (5) configured as described later, and when overshoot and undershoot as described in C69 and Ail are detected, Fi+
The control circuit (11) is controlled to maintain the output (v) at one of the corresponding predetermined values (aK (VL), (V)I). The hunting prevention circuit (5) includes seven O
R gates (G1) to (G4) and two timers (6a
), (5b) are provided, and when both the output (El) of the overshoot detection comparator (A8) and the output (Gl) of the differential value discrimination converter (A7) become "L & level, that is, the detected temperature is 14iF+ If the difference (Δt) is greater than or equal to the predetermined value (4-a l ), and the transformation rate (ga) is greater than or equal to the predetermined value (-+-a♀), O
A predetermined voltage (伽) corresponding to the resistor (Rn) is output (OI) at the level 1.
is added to the input of the differentiator (At) to obtain the detected voltage (va
) Lower limit value (VL) that maintains combustion at output (V) regardless of
At the same time, the timer (58) is started to prevent the other output (Os) from being understated until a certain period of time (τ) corresponding to one period of hunting that occurs without the anti-hunting circuit (5) has elapsed. “L” by shot detection
Similarly, the output (F) of each comparator (A4) for undershoot (C1) '* (As) is
, @ is input to the O, R gate (G), and when an undershoot is detected, the other timer (5b) is started and the one output (01) is prohibited until a certain period of time (τ) has elapsed. A predetermined voltage (VH) corresponding to the resistor (Rn) is added to the input of the integrator (A2) by the "L" level output (02), and the output (VH) of the control circuit ill is added to the input of the integrator (A2).
This is to set l to the upper limit value (VH) corresponding to the maximum supply amount. It should be noted that the integrator (At) has a mechanism that when the 19iJ output (V) is lowered to the lower limit value (vL), its operation is saturated and the integrator returns to its normal operating state in °C. In order to prevent delays, a limiter (A9) is provided as a saturation prevention means to control the output (V) so that it does not fall below the predetermined fat (VL) regardless of the input voltage μ. In addition, the diodes connected to the outputs of the limiter (A9), output (V), and OR (Gs) (Gs) and (G4) are used to prevent backflow to prevent malfunctions. In addition, in Figure 2, (2) is a proportional valve, and (3) is a PID system.
This is a proportional valve drive circuit that outputs a drive signal that determines the opening degree of the proportional valve (2) in response to the output (V) of circuit 1+11. Moreover, FIGS. 8(a) and 8(b) are time charts showing the operation of this embodiment explained above, in which FIG. 8(a) shows the case where overshoot occurs first, and FIG. ) indicates the case where undershoot occurs first. Another embodiment of the present invention will be described below. Each output (0+) of the henching prevention circuit (6). (02) are connected individually to each input of the differentiator (At) and integrator (A2) [and the output (0
+), (If the polarity of (h) matches the operating polarity of the differentiator (At) and integrator 4(A), the differentiator (A
1) or the above-mentioned both outputs (0+) to one of the integrator (A2)
. (02) may be connected, and its output (0+)
. The connection point (02) may be replaced. Furthermore, instead of outputting the outputs (0+) and C0t) independently, they may be combined into one output to generate outputs corresponding to 78I for overshoot and undershoot, respectively. Similarly, timer (5m), (5m)
b) may be configured to be shared by seven timers instead of being provided individually. In addition to using an operational amplifier as the N-sum prevention means (A9) described in II, any device such as a resistor or Zener diode that can operate as a limiter of the feedback shell may be used (PID control circuit (A9)). ) output (the upper limit value of Vl (Viθ) may also be configured to be regulated.Furthermore, the control circuit+11 or the entire combustion control device may be drawn by a microcomputer, and various configurations are possible. be.

[Brief explanation of the drawing]

1M is a block diagram showing the 1'14 configuration of the present invention, FIG. 2 is a circuit diagram showing the specific configuration of the combustion control device according to the present invention, and FIGS. 8(a) and (b) show its operation. A time chart and FIG. 4 are block diagrams showing the configuration of a conventional example. +11... Proportional control means, (4)... Transient response detection means, (6)... Hunting prevention means, (■1...]... Fuel supply amount, CAs ), (/
h)...Integrator, (to) Old...Set temperature, (t)...Detected temperature, (Δ[)...
Temperature deviation, (standing)... Rate of change, (C1), (
αri, (VL), (VH)...predetermined value, (τ)...predetermined time. Agent Patent Attorney Osamu Kitamura

Claims (1)

[Claims] (Li) In order to maintain the IIj temperature at the set temperature (to), the fuel supply it (Vl is proportionally Transient response detection means for detecting whether a convex transient response, overshoot or undershoot, has occurred in temperature control in a combustion control device in which the number of control means fl+ including at least an integrating means (AI) is increased to 6°. (4) If a transient response is detected by the transient response detection means (4) described in 0++, the output (V
), predetermined values (VL), (
The operation of the control means 11) is regulated to maintain one of the transient responses VH), and once one of the transient responses is detected, the other transient response is not detected until a certain period of time (τ) has elapsed. Even if the output (■) is set to the predetermined value (Vl
, ), (VH). ■ The transient response detection means (4) detects the set temperature (t
o) is configured to detect whether an overshoot or undershoot transient response has occurred based on the magnitude and direction of the deviation (Δ[) of the detected temperature (tl) and its direction. The combustion control device according to range 0. ■ The transient response detection means (4) is configured to detect the detected temperature (1).
) The combustion control according to claim 0 or 0, wherein the combustion control is configured to detect the occurrence of a transient response based on the magnitude of the ashing rate (ΔG) of Device. ■ The -foot time (τ) is determined by the hunting prevention means (
6) The combustion control device according to Claims 0 to 5, wherein the combustion control device is set to one cycle or more of hunting that would occur in the absence of 6).