JPH07243640A - Combustion controller - Google Patents

Abstract

PURPOSE:To provide a combustion device capable of performing slow ignitions such as ignition, transfer of fire, etc., under a proper air/fuel ratio condition to any of a plurality of kinds of fuels. CONSTITUTION:Upon combustion of a burner, the heating value ratio alpha=FR/F of a real output heating value FR to a target output heating value F is obtained. Output heating values upon ignition ad transfer of fire which are initialized in calculation storing parts 59 and 61 are corrected and stored based on the heating value ratio alpha. Upon next feed of a molten metal. the corrected output heating values upon ignition and transfer of fire which have been stored are read by correcting parts 65 and 67. Thus, the opening degree of a proportional valve 15 is controlled based thereon. Accordingly, the air/fuel ratio upon ignition and transfer of fire is adjusted based on the heating value ratio alpha. The heating value ratio alpha is learned every feed of a molten metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a combustion device such as a gas water heater, and more particularly to improvement of air-fuel ratio control during ignition.

[0002]

2. Description of the Related Art In a gas water heater, it has been known to control the air-fuel ratio to a gas-rich side as compared with that during normal combustion in order to ignite reliably during ignition such as ignition or transfer. For example, as shown in FIG. 1, when the ideal levels of the gas amount adjusting proportional valve current and the air amount adjusting fan rotation speed with respect to the required combustion output (heat amount) F are represented by solid line graphs A and B, normal combustion is performed. At times, the proportional valve current and the fan speed are controlled to the points b and c on the ideal graphs A and B, respectively, with respect to the required heat amount at the point a. However, at the time of slow ignition, the proportional valve current is set to the point e on the ideal graph A with respect to the required heat amount at the point d, but the fan rotation speed is set to the f point on the lower level side than the ideal graph B, so that the gas rich Ignition and transfer are performed with a certain air-fuel ratio.

[0003]

By the way, the gas water heater needs to be able to handle various kinds of gas, because the gas type varies depending on the area where it is used. For example, propane gas and butane gas having different Wobbe indices of 15% must be combustible in the same model.

When there is a possibility of using a plurality of kinds of gases having greatly different calorific values per unit mass as described above, if the slow ignition is performed under a uniform air-fuel ratio condition, it may be incomplete depending on the kind of gas. Combustion may occur or ignition failure may occur. For example, assuming that proper conditions are set for propane gas, if butane gas having a significantly higher Wobbe index is used, air may become too small and soot and CO may be generated. If proper conditions are set for butane gas, there is a possibility that ignition failure will occur due to excess air when using propane gas.

The same problem exists not only in the gas water heater but also in various combustion devices that burn a mixture of air and fuel.

Accordingly, an object of the present invention is to provide a combustion control device capable of performing a slow ignition operation such as ignition, transfer of fire, etc., under proper air-fuel ratio conditions for any of a plurality of fuel types.

[0007]

The combustion control device according to the first aspect of the present invention is based on an actual combustion state, means for calculating an index reflecting the exothermic ability of the fuel used, and the calculated exothermic ability. And means for adjusting the air-fuel ratio at the time of subsequent slow ignition.

A combustion control device according to a second aspect of the present invention is the device according to the first aspect, wherein the index calculating means comprises:
Each time combustion is performed, the index is calculated, and the air-fuel ratio adjusting means adjusts the air-fuel ratio at the time of slow ignition at the time of the current combustion based on the index calculated at the time of the previous combustion.

A combustion control apparatus according to a third aspect of the present invention is the apparatus according to the first aspect, wherein the heat quantity ratio between the target output heat quantity and the actual output heat quantity at the time of actual combustion, or the target output heat quantity and the required heat quantity. It is characterized in that a heat quantity ratio is calculated as the index.

A combustion control device according to a fourth aspect of the present invention is the device according to the third aspect, wherein the air-fuel ratio adjusting means has an output heat amount during slow ignition which is initially set in accordance with the heat amount ratio as the index. Is corrected, and the fuel supply amount is adjusted to match the corrected output heat amount at the time of slow ignition, or the air supply amount at the time of slow ignition initially set according to the heat amount ratio is corrected, and this correction is performed. It is characterized in that the fan rotation speed is adjusted so as to supply the air supply amount.

[0011]

With the combustion control device according to the first aspect of the present invention, when different types of fuel are used, an index reflecting the heat generation capacity of the used fuel is calculated, and in the case of slow ignition, the index is calculated. The air-fuel ratio of is adjusted. In general, a fuel having a high heat generating ability has a proper air-fuel ratio on the air rich side as compared with a fuel having a low heat generating ability. Therefore, by controlling the air-fuel ratio at the time of slow ignition with an index according to the heat generation capability, it is possible to perform slow ignition at an appropriate air-fuel ratio (slightly richer than the air-fuel ratio during normal combustion) for any type of fuel. It

According to the combustion control device of the second aspect of the present invention, the index is learned each time combustion occurs, and the next air-fuel ratio adjustment is performed based on the learned value. Therefore, even if the type of fuel used changes, or the performance of the device changes slightly due to the environment in which the device is placed or changes over time, an air-fuel ratio suitable for the used fuel is automatically set.

According to the combustion control device of the third aspect of the present invention, the heat quantity ratio between the target output heat quantity and the actual output heat quantity during actual combustion or the heat quantity ratio between the target output heat quantity and the required heat quantity is used as the index. Used. This heat quantity ratio is a value that reflects the difference in heat generation capability between the fuel type initially planned for the device and the fuel type actually used. Therefore, if the air-fuel ratio condition initially set in the device is adjusted based on this heat quantity ratio, the air-fuel ratio suitable for the actual fuel type used can be obtained.

According to the combustion control device of the fourth aspect of the present invention, at least one of the fuel supply amount and the air supply amount corresponding to the initial setting condition at the time of slow ignition is adjusted according to the heat quantity ratio. Therefore, the air-fuel ratio is adjusted according to the heat quantity ratio, and as a result, an appropriate air-fuel ratio according to the fuel type is obtained.

In the preferred embodiment, as a method of adjusting the air-fuel ratio, a method of adjusting the fuel supply amount or the air supply amount as a linear function of the heat quantity ratio, and whether the heat quantity ratio is larger than a predetermined threshold value (for example, 1) are used. A method is adopted in which the fuel supply amount or the air supply amount is adjusted in predetermined steps depending on whether the amount is small.

In the latter method, since the magnitude of the amount of adjustment is not directly related to the value of the heat quantity ratio, it is possible to properly adjust the air-fuel ratio by properly setting the adjustment step. However, when the heat generating capacities of a plurality of types of fuels used are significantly different, it is difficult to give an appropriate air-fuel ratio to all the fuel types in a uniform adjustment step. In such a case, several stages of adjustment may be prepared and selected according to the magnitude of the heat quantity ratio. On the other hand, in the former method, since the magnitude of the amount of adjustment is directly related to the value of the heat quantity ratio, by appropriately setting both functions,
Appropriate air-fuel ratio adjustment is possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a schematic structure of a main part of an embodiment of a gas water heater to which the present invention is applied.

As shown in FIG. 2, this water heater is equipped with two-stage burners 1 and 3, and solenoid valves 5 are respectively provided in branched gas supply pipes 5 and 7 to the two burners 1 and 3, respectively. , 7 are provided, and the original gas pipe 1 from which the gas supply pipes 5, 7 are branched
3 is provided with a proportional valve 15 for adjusting the gas amount. Further, an intake fan 29 is provided to send necessary air to the burners 1 and 3.

A heat exchanger 17 is arranged opposite to the burners 1 and 3, and a water supply pipe 19 and a hot water supply pipe 23 are connected thereto. A water inlet temperature sensor 21 for measuring the water inlet temperature TC is attached to the water supply pipe 19, and a hot water outlet temperature sensor 25 for measuring the hot water outlet temperature TM and a flow rate sensor 27 for measuring the hot water outlet flow rate Q are attached to the hot water supply pipe 23. These sensors 2
The outputs of 1, 25 and 27 are sent to the control device 31. As will be described later, the control device 31 uses the information TC, TM, Q from these sensors, the set hot water temperature TS from the hot water temperature setter (not shown), and the like to supply gas control valves 9 and 1 described above.
It controls the driving of the intake fans 1, 13, the intake fan 27, an igniter (not shown), and the like.

FIG. 3 shows a functional configuration of a portion of the control device 31 related to the present invention.

In FIG. 3, the required heat amount calculation unit 43, based on the set temperature TS, the incoming water temperature TC and the flow rate Q, the required heat amount F1 = (TS-TC) for turning the incoming water into the hot water of the set temperature.
Calculate Q. This required heat amount F1 is sent to the comparison unit 51, and the comparison unit 51 outputs the required heat amount F1 to the minimum ignition number (for example, No. 2) which is the ignition condition of the first stage burner stored in advance in the minimum ignition number storage unit 49. ) And the number of required fire transfer, which is the ignition condition of the second stage burner, and output the comparison results.

The comparison unit 55 compares the flow rate Q with the minimum ignition flow rate, which is the ignition condition of the first stage burner stored in advance in the minimum ignition flow rate storage unit 53, and outputs the result.

The output of the comparison unit 51 and the output of the comparison unit 55 are combined to form the first-stage solenoid valve 9, the igniter 69, the second-stage solenoid valve 11, the present ignition air-fuel ratio correction unit 67, and the present ignition transfer air-fuel ratio. It is given to the correction unit 65.

The first-stage solenoid valve 9 and the igniter 69 operate when the required heat quantity F1 exceeds the minimum ignition number and the flow rate Q exceeds the minimum ignition flow rate, and ignites the first-stage burner 1. At this time, the current ignition air-fuel ratio correction unit 67 operates to control the opening of the gas proportional valve 15 and the rotation speed of the fan 29,
As a result, slow ignition is performed with an air-fuel ratio suitable for ignition and with the number of the ignition.

Further, the second-stage solenoid valve 11 operates when the required heat quantity F1 exceeds the required number of fire transfer after ignition, and causes the first-stage burner 1 to transfer to the second-stage burner 3. At this time, the fire transfer air-fuel ratio correction unit 67 is activated this time,
By controlling the opening degree of the gas proportional valve 15 and the rotation speed of the fan 29, the transfer of the fire to the second stage burner is performed with the air-fuel ratio suitable for the transfer of fire and the number at the time of transfer. It should be noted that the igniter 69 may be operated in order to ensure this during a fire transfer.

The flow rate stability detecting section 35 and the tapping temperature stability detecting section 37 respectively calculate the flow rate Q and the tapping temperature TM when the flow rate Q and the tapping temperature TM are stable.
Send to.

The actual output calculation unit 45 calculates the actual output heat quantity FR = (TM-TC) Q actually output from the burner based on the incoming water temperature TC, the stabilized flow rate Q and the hot water temperature TM.
Is calculated.

The output calculation unit 41 sets the set temperature TS, the incoming water temperature TC and the flow rate Q, and the output heat amount correction coefficient K which is the calculation result of the feedforward feedback control calculation of the output heat amount given from the output heat amount correction unit 39. Based on this, the target output heat quantity F that the burner should actually output is calculated.

The comparison unit 47 inputs the actual output heat amount FR and the target output heat amount F, and the heat amount ratio α = FR /
Find F. This heat quantity ratio α is an index indicating whether or not the current combustion conditions of the device are suitable for the type of gas used, and if α = 1, it means that it is suitable, and α <1 means that the equipment condition is set to a gas type having a Wobbe index lower than that of the gas type being used,
If α> 1, it means the opposite. Therefore, the present control device adjusts the air-fuel ratio at the time of ignition and transfer in accordance with the value of this heat quantity ratio α so as to match the gas species in use, by the configuration described below.

The next slow ignition output calculation storage unit 61 stores the reciprocal 1 / α of the heat quantity ratio α from the comparison unit 47 in the initial value storage unit 63.
It is corrected for use at the next ignition of the first-stage burner by multiplying it by the initial setting slow-ignition heat amount FK0 (for example, No. 4) which is the amount of heat at the time of slow ignition (ignition) of the first-stage burner that is initially set The slow ignition heat amount FK = FK0 / α is calculated and stored.

The next ignition transfer output storage unit 59 stores the reciprocal 1 / α of the heat quantity ratio α from the comparison unit 47 into the initial value storage unit 57.
The corrected heat transfer heat quantity FU = FU0 / α for use at the next heat transfer by multiplying the initial heat transfer heat quantity FU0 (for example No. 10) which is the output heat quantity at the time of heat transfer Is calculated and stored.

The current ignition air-fuel ratio correction unit 67 controls the air-fuel ratio at the time of the first stage burner ignition as described above. At that time, the next slow ignition output calculation unit 61 calculates it at the time of the previous combustion. Stored corrected slow ignition heat quantity FK (= FKO /
α) is read out, the gas proportional valve 15 is controlled so that the gas flow rate corresponds to this FK, and the fan rotation speed corresponds to the initial setting slow ignition heat quantity FK0. At point f, when point d is set to FK0, control is performed. As a result, the air-fuel ratio at ignition is adjusted according to the heat quantity ratio α from the set conditions of the device. That is, if α = 1, the air-fuel ratio is the same as the set condition, but if α <1, the air-fuel ratio is controlled to the gas rich side further than the set condition, and it is appropriate for gas types with a lower Wobbe index. On the other hand, when α> 1, on the other hand, when α> 1, the air-fuel ratio is controlled to the air rich side from the set condition, and the gas rich state is appropriate for the gas type having a higher Wobbe index.

The current transfer heat air-fuel ratio correction unit 65 controls the air-fuel ratio at the time of transfer of heat to the second stage burner, as described above. At that time, the next transfer transfer output calculation unit 59 calculates it. The gas proportional valve 15 is controlled so that the gas flow rate corresponds to the stored corrected transfer heat quantity FU (= FUO / α), and the fan rotation speed is a value corresponding to the initial setting FU0 (for example, FIG. 1). F when d point is FU0 in
Control). As a result, the air-fuel ratio at the time of fire transfer is adjusted according to the heat quantity ratio α from the set condition of the device, as in the case of ignition, and as a result, it is in a proper gas rich state for the gas species in use. .

FIG. 4 shows the flow of the control operation of the air-fuel ratio performed under the above functional configuration.

First, the required heat quantity F1 = (TS-TC) Q is calculated (step 100), and then the required heat quantity F1 exceeds the minimum number of ignitions (for example, 2) and the flow rate Q is the minimum ignition flow rate ( For example, it is checked whether it exceeds 2 liters / minute (step 101).

If the check result in step 101 changes from NO to YES, it means that the hot water has started.
Proceed to 02 to perform the ignition operation of the first stage burner. That is,
Open the gas proportional valve 15 to the opening corresponding to the corrected slow ignition heat quantity FK calculated at the previous combustion (initial setting slow ignition heat quantity FK0 only for the first time), open the solenoid valve 9 of the first stage burner, and change the fan speed. The engine speed is controlled to a value corresponding to the initially set slow ignition heat quantity FK0, and the igniter 69 is energized.
As a result, the first-stage burner 1 is ignited, but in this case, slow ignition is performed in an appropriate gas rich state according to the gas type.

Next, by comparing the required heat quantity F1 with the necessary heat transfer quantity, it is judged whether or not the second stage burner 3 needs to be ignited (step 103). If the result is no, the routine proceeds to step 105, where normal combustion is started, and if the result is yes, the routine proceeds to step 104 where the transfer operation to the second stage burner 3 is performed, and then step 1
Proceed to 05 normal combustion.

In the transfer operation of step 104, the gas proportional valve 1 is opened at the opening corresponding to the corrected transfer heat quantity FU calculated at the previous combustion (initially set transfer heat quantity FU0 only for the first time).
5 is opened, the solenoid valve 11 of the second stage burner is opened, and the fan rotation speed is controlled to the rotation speed at the time of the fire transfer corresponding to the initial setting heat transfer heat FU0. The igniter 69 may be further energized. As a result, the second-stage burner 3 is ignited by the transfer from the first-stage burner 1, but in that case, the transfer is performed in an appropriate gas-rich state according to the gas type as in the case of ignition.

In the normal combustion of step 105, the target output heat quantity F is set by the feedforward feedback control.
Is calculated, the proportional valve 15 is controlled to an opening corresponding to this, and the fan rotational speed corresponding to this proportional valve opening (for example, point c when point a in FIG. 1 is set to F) is controlled. To be done.

When this normal combustion is started, the outlet heated water temperature T
It is checked whether both M and the flow rate Q are stable (step 106). If so, the actual output heat amount F at that time is checked.
R = (TM-TC) Q is calculated (step 107), and the heat quantity ratio α = FR / F between the actual output heat quantity FR and the target output heat quantity F at that time is calculated (step 108).

Next, by dividing this heat quantity ratio α into the initial set slow ignition heat quantity FK0 and the initial set fire transfer heat quantity FU0, the corrected slow ignition heat quantity FK (= FK0 / α) and the corrected fire transfer heat quantity FU (= FU0) are calculated. / Α) is calculated (step 109).
The corrected slow ignition heat quantity FK and the corrected fire transfer heat quantity FU are stored for use in steps 102 and 104 at the next hot water discharge.

As described above, the difference in the output calorific value between the gas type scheduled for the initial setting condition of the apparatus and the gas type actually used is learned each time combustion is performed, and based on the learned contents. Since the air-fuel ratio at the time of ignition or transfer is adjusted from the set condition, even if different gas types are used, it is possible to automatically perform ignition and transfer operation accurately in an appropriate gas rich state. .

Further, although not shown, F in the state of α> 1
Corrected slow ignition with K and FU, α is 1 when misfire due to fire transfer
It is also possible to reset to and try again in the initial state.

FIG. 5 shows a functional configuration of the control device according to the second embodiment of the present invention.

The difference of this functional configuration from that shown in FIG. 3 is that when the comparison unit 47 obtains the heat quantity ratio α, it is calculated from the target output heat quantity F and the required heat quantity F1 by the formula α = F1 / F. Is. For the target output heat quantity F, feedback calculation (usually PI
Since the calculation result is included, the ratio between the target output heat amount F and the required heat amount F1 also reflects the difference in the output heat amount between the gas type initially planned by the device and the actual gas type used. It can be used to adjust the air-fuel ratio according to the gas type.

The control operation of this embodiment is exactly the same as that of FIG. 4 if the processing of step 108 in the flow chart of FIG. 4 is α = F1 / F as shown in parentheses. .

FIG. 6 shows a functional configuration of the control device according to the third embodiment of the present invention.

This functional configuration differs from that shown in FIG. 3 in the way of utilizing the heat quantity ratio α = FR / F calculated by the comparison section 47. That is, the comparison unit 75 receives the heat quantity ratio α,
The threshold value (= 1) stored in the threshold value storage unit 75 is compared with the heat quantity ratio α, and the result (that is, α = 1 or α <1 or α
> 1) is output. Then, the next slow ignition output calculation storage unit 61 and the next ignition transfer output calculation storage unit 59 respectively receive the comparison results, and when α = 1, the initial setting slow ignition and the heat transfer heat amounts FK0 and FU0 are directly corrected and corrected. Although the heat transfer heat amounts FK and FU are stored, when α> 1 or α <1, the initial set heat amounts FK0 and FU0 are corrected as follows.

(1) When α> 1 FK = FK0−ΔFK FU = FU0−ΔFU (2) When α <1 FK = FK0 + ΔFK FU = FU0 + ΔFU Here, ΔFK and ΔFU are predetermined FK and FU, respectively.
Is the adjustment amount of.

On the basis of the correction heat quantities FK and FU thus obtained, the air-fuel ratio control at the time of the next ignition and fire transfer is performed as already described.

Regarding the threshold value of α, for example, α ≧ 1.
1, 1.1> α ≧ 0.9, α ≦ 0.9 may be set.

The flow of the control operation of this embodiment is the same as that shown in FIG. However, the correction calculation in step 109 is performed as described above.

FIG. 7 is a flow chart showing the control operation of the fourth embodiment of the present invention.

The difference between this embodiment and the first to third embodiments already described is that the fan rotation speed is adjusted instead of the proportional valve opening according to the heat quantity ratio α. That is, in step 110 of igniting the first stage burner, the proportional valve 15
Is opened to an opening degree corresponding to the initially set slow ignition heat amount FK, and the fan speed is controlled to the corrected slow ignition air amount AK. Further, in step 111 where the transfer of heat is performed, the proportional valve 15 is opened to an opening corresponding to the initial set transfer heat quantity FU, and the fan speed is controlled to the corrected transfer heat quantity AU. Here, the corrected slow ignition and the transfer air flow rates AK and AU are the values obtained in step 1 of the previous combustion.
12, the reciprocal of the heat quantity ratio α is set to the initial setting slow ignition and the transfer air volume AK0, AU0 (for example, point d in FIG.
By multiplying f point when FU0 is set, AK = AK
It is calculated and stored as 0 / α and AU = AU0 / α.

The other processing is exactly the same as in FIG.

In this embodiment also, the heat quantity ratio α is set to α
= F1 / F, or the correction calculation in step 112 may be performed as follows based on the comparison result between α and the threshold value 1.

(1) When α> 1, AK = AK0 + ΔAK AU = AU0 + ΔAU (2) When α <1 AK = AK0−ΔAK AU = AU0−ΔAU Here, ΔAK and ΔAU are predetermined AK and AU, respectively.
Is the adjustment amount of.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment and can be implemented in various other modes. For example, the present invention can be applied to a combustion device of a type that injects liquid fuel as fuel.

[0059]

According to the present invention, since the air-fuel ratio at the time of slow ignition is controlled on the basis of the index reflecting the exothermic ability of the fuel used, at the time of proper slow ignition for a plurality of different fuels. The air-fuel ratio of can be set.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional method for controlling an air-fuel ratio at ignition and transfer to be gas rich.

FIG. 2 is a block diagram showing a schematic configuration of a main part of an embodiment of a gas water heater to which the present invention is applied.

FIG. 3 is a block diagram showing a functional configuration of a control device of the same embodiment.

FIG. 4 is a flowchart showing a control operation of the embodiment.

FIG. 5 is a block diagram showing a functional configuration of a control device according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a functional configuration of a control device according to a third embodiment of the present invention.

FIG. 7 is a flowchart showing the control operation of the fourth embodiment of the present invention.

[Explanation of symbols]

 1 First Stage Burner 3 Second Stage Burner 9 First Stage Solenoid Valve 11 Second Stage Solenoid Valve 15 Proportional Valve 21 Inlet Water Temperature Sensor 25 Outlet Water Temperature Sensor 27 Flow Rate Sensor 29 Intake Fan 31 Control Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuaki Baba 43-1, Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Nihon Yupro Co., Ltd. No. 1 Nihon Yupro Co., Ltd. (72) Inventor Toru Tsuruta 43-1 Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Nihon Yupro Co., Ltd.

Claims (6)

[Claims] 1. A combustion control device for adjusting an air-fuel ratio at the time of slow ignition, a means for calculating an index showing a heat-generating ability of a fuel used based on an actual combustion state, and a means for calculating a heat-generating ability of the fuel used thereafter. And a means for adjusting the air-fuel ratio at the time of slow ignition of the combustion control device. 2. The apparatus according to claim 1, wherein the index calculating means calculates the index each time combustion is performed, and the air-fuel ratio adjusting means calculates the index based on the index calculated at the previous combustion. A combustion control device characterized by adjusting the air-fuel ratio at the time of slow ignition during the current combustion. 3. The combustion control device according to claim 1, wherein the index calculation means calculates a heat quantity ratio between a target output heat quantity and an actual output heat quantity during actual combustion as the index. 4. The combustion control device according to claim 1, wherein the index calculation means calculates a heat quantity ratio between a target output heat quantity and a required heat quantity during actual combustion as the index. 5. The apparatus according to claim 3, wherein the air-fuel ratio adjusting means corrects the output heat quantity at the time of slow ignition which is initially set according to the heat quantity ratio, and the corrected output at the time of slow ignition. A combustion control device characterized in that the fuel supply amount is adjusted to match the heat amount. 6. The apparatus according to claim 3 or 4, wherein the air-fuel ratio adjusting means corrects an air supply amount at the time of slow ignition which is initially set according to the heat amount ratio, and uses the corrected air supply amount. A combustion control device characterized in that the fan speed is adjusted so as to supply it.