JPS59219622A - Gas combustion controller - Google Patents

Abstract

PURPOSE:To improve air-fuel ratio control precision and to widen the regulation range of a combustion amount, by constituting a device such that control is effected by the use of a differential pressure sensor so that the upper stream pressure of an air throttle is normally kept equal. CONSTITUTION:Provided that a burner 15 for combustion burns a given type of gas in a normal manner and if, with this, a change is produced so that the burner 15 for combustion is increased in a combustion amount, an air amount regulating means 5 is operated so as to increase an air amount. Thus, a differential pressure force, based on a pressure difference DELTAP=PA-PG>O between an upper stream pressure PA of a variable primary air throttle 8 and an upper stream pressure PG of a regulation type nozzle 3, is produced at a differential pressure sensor 11. A differential pressure output signal therefrom is processed by an electric circuit 12 to regulate a gas amount regulating means 2 so that a gap amount is increased and to effect control making PA=PG, i.e., a pressure difference is brought to zero. If the differential pressure sensor 11 including an electric system has no error, an air-fuel ratio is kept constant even if a combustion amount is regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gas combustion control device that can improve the combustibility of a burner depending on its combustion characteristics.

Structure of Conventional Example and Its Problems As a conventional gas combustion control device of this type, the pressure equalization valve system (or zero governor system) shown in FIG. 1 is well known. That is, the air sent by the blower 1 passes through the air constrictor 2 and enters the mixing section 3, and the gas passes through the pressure equalizing valve 4 and gas constrictor 5 and enters the mixing section 3, where the air and gas are mixed. After the pressure is restored by the diffuser 6, the gas passes through a first pressure equalizing plate (not shown) in the burner 7, and is ejected from a flame hole (not shown) to be burned. On the other hand, the secondary air branched from between the blower 1 and the air constrictor 2 passes through the fixed secondary air constrictor 8 (usually installed inside the burner 7), and then passes through the secondary air outlet of the burner 7 ( (not shown). The pressure upstream of the air restrictor 2 is introduced into the back pressure chamber 9 of the pressure equalizing valve 4, and the pressure equalizing valve 4 automatically adjusts the pressure at the outlet of the pressure equalizing valve to be equal to the pressure in the back pressure chamber 9. In addition, 10 is a diaphragm, 11
is a movable knob f that is directly connected to the center portion of the diaphragm 10.

Here, the pressure of the second flow of air throttle 2 is PA, and the pressure of gas throttle 5 is
If the pressure upstream of Becomes a value.

However, in the pressure equalizing valve 4, a control error occurs that prevents PA from becoming equal to Pa due to the rigidity of the diaphragm, changes in the effective pressure receiving area, etc., and this becomes noticeable especially when the combustion amount is lowered. This made it difficult to achieve the combustion amount adjustment ratio required for household combustion equipment. Even more air! Since the 1l 12 and Ganu diaphragm 5 are fixed diaphragms, the primary air ratio is constant, and the diaphragm arranged in the burner 7 that adjusts the amount of secondary air is the fixed secondary air diaphragm 8. However, because it cannot be adjusted according to the combustion characteristics of the burner, when the combustion amount is reduced depending on the type of gas, yellowing or backing may occur, which narrows the stable combustion range of the burner. The drawback was that the combustion adjustment range could not be widened.

OBJECT OF THE INVENTION The present invention solves these conventional problems, and aims to increase the combustion amount control ratio and control the control ratio so that it remains almost constant even when the type of gas changes. .

Structure of the Invention The present invention includes a differential pressure sensor that detects the pressure difference between the upstream side of the adjustable gas nozzle and the upstream side of the variable primary air restriction, and uses the output of this differential pressure sensor to control the gas amount adjusting means or the air amount adjusting means. The device is configured to control one or both of the means, and is configured to control the amount of primary air and the amount of secondary air necessary for combustion by means of an adjustable gas nozzle, a variable primary air restrictor, and a variable secondary air restrictor. It is constructed so that it can be adjusted with an air throttle, and by improving the combustion characteristics of the burner, the combustion amount adjustment range is expanded, and the combustion amount adjustment ratio does not change even if the gas type changes.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

1 is an air side passage that supplies combustion air, 1G is a gas side passage that guides combustion gas, and 2 is a gas amount adjusting means such as a gas pressure proportional control valve. 3 is an adjustable gas nozzle configured so that the throttle opening can be variably adjusted depending on the type of gas when the rated input is flowing at a predetermined pressure, and 3a is an adjustable gas nozzle when the rated input is flowing at a predetermined pressure.
Adjustment needle/l for variably adjusting the throttle opening of I/3
/A, 4 is a blower that supplies the air necessary for combustion, 5 is an air volume adjustment means such as a damper, 6 is the primary air passage, 7 is the secondary air passage, 8 is the primary air volume at the rated input The variable primary air restrictor 9 is a mixing section configured in the shape of a Venturi tube and is used to mix gas and air with low pressure loss.

Reference numeral 10 indicates a variable secondary air throttle for adjusting the amount of secondary air disposed in the secondary air passage 7, and reference numeral 10a indicates an adjustment needle (vB) for adjusting the variable secondary air throttle.

11 is an adjustable gas nozzle/1/3 upstream pressure PG and variable 1
A differential pressure sensor 12 detects the pressure difference between the downstream air restrictor 8 and the upstream pressure member JP, and 12 is an electric circuit for driving the gas amount adjusting means 2 with the output signal of the differential pressure sensor 11.

13 is the total pipe resistance of the mixed gas system including the flame hole through which the mixed gas of gas and air flows, 14 is the total pipe resistance of the secondary air system including the secondary air nozzle, and 15 is the combustion/burner It is.

In the above configuration, the adjustable gunnozzle/L'3, the variable primary air throttle 8, and the variable secondary air throttle 10 are already set in accordance with the combustion characteristics of the combustion burner 15 for the predetermined gas type. Assume that it is burning.

In such a state, if the load on the combustion burner 15 is changed, for example to increase the amount of combustion, the air amount adjusting means 5 operates to increase the amount of air. Therefore, the differential pressure sensor 11 detects the upstream pressure PA of the variable primary air throttle 8 and the upstream pressure PG of the adjustable gas nozzle 3.
A differential pressure output is generated based on the pressure difference ΔP=Pa−Pc)o. Then, this differential pressure output signal is sent to the electric circuit section 12.
The gas amount adjusting means 2 is controlled so that the gas amount increases, and is controlled so that PA:=PG, that is, the pressure difference becomes zero. If there is no error in the differential pressure sensor 11 including the electric control system, the air-fuel ratio will be maintained constant even if the combustion amount is adjusted.

FIG. 4 is a diagram showing the air-fuel ratio control characteristics in this case.

In other words, if we take the air amount Qm on the horizontal axis and the gas amount QG on the vertical axis, we will find a limited system in which the throttle opening of the adjustable gas nozzle 3, the variable primary air throttle 8, and the variable secondary air throttle 1o are constant. , the ratio of the total air amount, which is the sum of the primary air amount and the secondary air amount, and the gas amount, that is, the air-fuel ratio control characteristic changes along a straight line b' (standard). Even if the combustion amount changes, the air-fuel ratio remains constant. Further, the relationship between the primary air amount and the gas amount in this case is a straight line b (standard).

Note that the straight lines 1' and (!/ are the characteristics when the total air volume is adjusted to the minimum qtN and maximum qtM at the rated input, and the straight lines a and c are 1 at the rated implant l-. This is the characteristic when the secondary air amount is adjusted to a minimum qIN and a maximum q1M.

Now, when the air-fuel ratio control characteristic is set for a predetermined gas (for example, city gas) is b', the gas type is changed to a gas with a high calorific value such as propane gas and a low flow rate. By adjusting the adjustable gas nozzle 3 and variable primary air throttle 8 to predetermined values in order to match the combustion characteristics of the combustion burner 15 corresponding to The ratio of the gas amount to the primary air amount and the total air amount at the maximum rated gas amount (, MAX) can be set in any combination between qlN to (hM and qtN and (ltM). For example, It is possible to maintain the quantity-order air quantity characteristic at the characteristic b and adjust the gas quantity total air quantity characteristic to a characteristic between a' and C' in response to the gas type, and vice versa. As described in the detailed description of the invention, the primary air volume characteristic can be variably adjusted to a characteristic between a and C in accordance with the gas type while maintaining the total air volume characteristic at the characteristic b'. In addition, the present invention uses a differential pressure sensor so that the upstream pressure of the adjustable gas nozzle and the upstream pressure of the variable primary air restrictor (or variable secondary air restrictor) are always equal, even when the combustion amount is adjusted. configured to control either the gas amount adjusting means or the air amount adjusting means, but not both;
In addition, in accordance with the combustion characteristics of the burner or in accordance with the gas type, an adjustable gas nozzle, a variable primary air restriction, and a variable secondary
By arranging the secondary air restriction so that it can be adjusted, the following effects can be obtained. That is, 1) air-fuel ratio control accuracy in gas combustion equipment, especially high-load burner combustion equipment, is improved, and the range of combustion amount adjustment can be made wider than before.

2) The crocodile burning characteristics of the burner can of course be arbitrarily adjusted based on the overall viewpoint of the gas combustion equipment, such as the pressure flow characteristics of the blower, combustion noise, and air-fuel ratio control accuracy.

3) Adjustment can be made to expand the stable combustion range according to the combustion characteristics of the burner.

4) Even when the gas type is changed, the combustion amount can be adjusted within a constant range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional gas combustion control device, FIG. 2 is a block diagram showing an embodiment of the gas combustion control device of the present invention, and FIG.
The figure shows the configuration of the device in terms of a pipe resistance system, and FIG. 4 shows the air-fuel ratio control characteristics of the device. 1 person...Air side passage, 1G...Gas side passage, 2...Gas amount adjustment means, 3...Adjustable gas nozzle, 4...・Blower, 5...
Air amount adjustment means, 6...Primary air passage, 7...
...Secondary air passage, 8...Variable primary air restriction, 9...Mixing section, 10...Variable secondary air restriction, 11... ...Differential pressure sensor, 15...
...Burna. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (2)

[Claims] (1) The gas side passage is provided with a gas amount adjusting means and a regulating type gas nozzle, and the air side passage is provided with a blower that supplies combustion air and an air amount adjusting means, and the wake of the air amount adjusting means is 1. The primary air passage is divided into a primary air passage and a secondary air passage, and the primary air passage has a variable primary air restriction, and the downstream of the variable primary air restriction and the adjustable gas nozzle are merged to form a gas and air passage. and a variable secondary air throttle is disposed in the secondary air passage, and the upstream pressure of the adjustable gas nozzle and the upstream pressure of the variable primary air throttle are further disposed in the secondary air passage. A gas combustion control device comprising a differential pressure sensor that outputs an electrical signal corresponding to a pressure difference, and configured to control at least one of the gas amount adjusting means and the air amount adjusting means using the output signal of the differential pressure sensor. . (2) A gas combustion control device according to claim 1, in which a part of the variable primary air throttle and the mixing section are integrated and have a venturi tube shape.