JPS5931648B2 - fuel supply control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply control device that attempts to maintain a nearly constant temperature rise by supplying a fuel needle to a burner in accordance with the flow rate of a fluid to be heated. This invention relates to a gas water heater, and its first purpose is to easily set the ratio between the flow rate of the heated body and the amount of fuel supplied, that is, the temperature rise.

A second object of the present invention is to enable easy remote control of the setting of the temperature rise from the outside.

A third object of the present invention is to enable the temperature rise setting to be changed without substantially changing the flow rate of the fluid to be heated.

It is already known in instantaneous gas water heaters to supply a gas quantity proportional to the water supply.

For example, in Utility Model Publication No. 51-34724, the temperature setting is changed by a regulating valve installed in the middle of the water circuit, but since the entire amount of water is flowing through the regulating valve, it becomes large (and the pressure loss This is accompanied by an increase in water supply and fluctuations in water supply.

In Japanese Patent Publication No. 37-14002 and Utility Model Publication No. 49-38623, a control valve is provided in the bypass passage of the ventuto pipe to change the setting of the ratio, but the ratio is set thicker (compared to the bypass passage in order to change it). A large flow rate of fluid must be flowed, and the flow rate changes considerably when the settings are changed.

As mentioned above, among conventional devices that supply fuel in proportion to the amount of water supplied, there is no device that can easily change the proportional ratio without changing the amount of water supplied, and that is small.

The present invention eliminates these conventional drawbacks, and embodiments thereof will be described below with reference to the drawings.

One embodiment of the present invention will be described in the case of an instantaneous gas water heater in which the fluid to be heated is water and the fuel is gas, but the present invention is not particularly limited to this.

In the figure, water enters from a water pipe 1, passes through a pressure difference generator 4 having a constriction part 2 and an enlarged part 3 connected thereto, is heated by a heat exchanger 7, and is discharged from a faucet 8.

The water pressure just before the throttle part 2 of the pressure difference generator 4 is detected from the high pressure tap 5, and the water pressure at the throttle part 2 is detected from the low pressure tap 6, respectively, and the pressure is introduced to the force generator 13 and the on-off valve drive part 29, which will be described later. It will be destroyed.

Next, the gas enters from the gas pipe 9, passes through the on-off valve 10, is controlled by the fuel pressure controller 11 to a supply gas pressure that has a certain relationship with the amount of water, and then reaches the burner 12 where it is combusted.

Reference numeral 13 denotes a force generating body, in which a main diaphragm 14 and two balance diaphragms 16.degree. 15 having a slightly smaller diameter and arranged concentrically are fixed together by a shaft 19.

One chamber sandwiched between three diaphragms constitutes a high pressure chamber 17 and communicates with the high pressure tap 5 through a pressure conduit 30, and the other chamber serves as a low pressure chamber 18 and communicates with the low pressure tap 6 and a pressure conduit. It communicates with 31.

These pressure conduits 30 and 31 are connected to each other and the control valve 3
The outsides of the balance diaphragms 15 and 16 into which the balance diaphragms 2 are inserted are both open to atmospheric pressure.

A spring 20 acts on the upper end 19a of the shaft 19 in the direction from the low pressure chamber 18 to the high pressure chamber 17.

Further, since the shaft 19 engages with the lever 21 near the upper end 19a, the displacement of the shaft 19 is magnified at the lever free end side due to the positional relationship with the lever fulcrum 22.

Next, the fuel pressure controller 11 has an actuator 23 that adjusts the opening degree of a control hole 24 in the gas passage, and this actuator 23 is fixed to a fuel diaphragm 25.

A control spring 26 is attached to the fuel diaphragm 25, and the control spring 26 always acts in the direction of opening the actuator 23.
The other end is supported by a support screw 27 fitted into an internal thread of a slide body 28 that is slidable in the opening/closing direction of the actuator 23.

Since the effective pressure receiving area of the fuel diaphragm 25 is designed to be approximately equal to the area of the control hole 24, the gas supply source pressure acts on the fuel diaphragm 25 to cause a force in the direction of closing the actuator 23 and a force acting on the actuator 23. A force is generated in the direction of opening the actuator 23, but since the two forces are equal and opposite in direction, as a result, no force is generated to move the actuator 23.

on the other hand. The pressure supplied to the burner that has passed through the control hole 24 acts on the actuator 23, and the position of the actuator 23 is determined by the balance point between this force and the force of the control spring 26.

If the slide body 28 does not move, the force of the control spring 26 will not change, so even if the gas supply source pressure changes, the gas pressure supplied to the burner 12 will remain almost constant, just like a normal gas pressure regulator. It has the function of maintaining

Since the slide body 28 is supported by the free end of the aforementioned lever 21, the displacement of the lever 21 results in a change in the load on the control spring 26, which in turn causes a change in the gas pressure.

Reference numeral 29 denotes a drive unit to which the high pressure tap 5 and low pressure tap 6 of the pressure difference generator 4 are connected, and which generates force by the pressure difference to open and close the on-off valve 10 of the gas circuit.

This part has the same mechanism as a normal instantaneous gas water heater, so a detailed explanation will be omitted.

The present invention attempts to make the amount of water and the amount of gas proportional.

In the pressure difference generator 4 of FIG. 1, the relationship between the change ΔPw in the pressure difference between the high pressure tap 5 and the low pressure tap 6 due to the water amount change ΔQw is as follows: ΔPw=kwΔQ W'
(1) Here, kw is a constant determined by the shape and dimensions of the pressure difference generating body 4 such as the throttle part.

This water pressure is guided to the high pressure chamber 17 and low pressure chamber 18 of the force generator 13, so if the effective area of the main diaphragm is S and the effective area of the balance diaphragm is S, the change in force in the force generator 13 is as follows. It will be as follows.

(S-s)ΔPW ・・・・・・・・・・・・
(2) Here, if S−s is expressed as ΔS, a force change of 3832w will occur.

This force change causes the lever 21 to change its position.

In FIG. 1, let X be the distance from the position where the shaft 19 abuts the lever to the lever fulcrum 22, and let Y be the distance from the lever fulcrum 22 to the position where the free end abuts the slide body 28.

Then, the amount of lever movement due to the water amount change ΔQw is set to Δy at the free end, and 9 shafts per shaft.

Further, when the spring constant of the spring 20 is expressed as K and the spring constant of the control spring 26 is expressed as k, and the balance condition of the rotational moment acting on the lever 21 is determined, ΔSΔPwX=ΔXKX+
Δyk Y ・−・−・−(3) Here, since the lever 21 is a rigid body, α is called the lever ratio.

Then, the third equation becomes ΔSΔPw=ΔxK+αΔyk, and Δy...
...(5) is obtained.

Now, the movement of the free end of the lever Δy results in a change in the force of the control spring, which in turn results in a change in the gas supply pressure to the burner 12, ΔPg.

The relationship is as follows: ΔPgA=Δyk ・・・・・・・・・
(6) However, A is the effective area of the fuel diaphragm 25, which is approximately equal to the area of the control hole 24 as described above.

becomes.

It is generally known that gas pressure and gas amount have the following relationship, where the constant between them is Kg.

However, the change in gas is expressed as ΔQg. In this equation (8), (1
) and (7), the equation a is integrated, and when Qw-0, Qg=O(, so the water amount Qw and the gas amount Qg are proportional.

Next, a method of changing the temperature setting by changing the proportional relationship of equation 00) will be described.

Since the control valve 32 is located at a position that short-circuits the high pressure chamber 1γ and the low pressure chamber 18, even if the flow rate does not change and the differential pressure at the differential pressure generator remains the same, the differential pressure acting on the force generator 13 will be the same as that of the control valve 32. It changes depending on the opening degree.

For this reason, the value of kW in equation (1) changes depending on the opening degree of the control valve 32, and as is clear in the test a, the proportional relationship between the water amount and the gas flow also changes, making it possible to change the temperature setting.

Since the pressure conduits 30 and 31 only transmit pressure, they can be small diameter pipes (therefore, the control valve 32 can also be small.

Since the configuration is as described above, in the present invention, the control valve 32
It is possible to vary the set temperature without changing the flow rate of the heated object depending on the opening degree, which is not only convenient to use, but also eliminates the need to provide the control valve 32 in the pressure differential generator 4 since it is in the pressure conduit system. Therefore, it has the effect of reducing the size of the valve.

[Brief explanation of the drawing]

The figure is a configuration diagram of an instantaneous gas water heater in one embodiment of the present invention. 1... Water piping, 4... Pressure difference generator,
5... High pressure tap, 6... Low pressure tap, 7... Heat exchanger, 8... Faucet, 9...
...Gas piping, 11...Fuel pressure controller,
13... Force generator, 14... Main diaphragm, 15, 16... Balance diaphragm, 19... Shaft, 20... Spring , 21・
...Lever, 23... Actuator, 25...
...Fuel diaphragm, 26...Control spring, 28...-Slide body, 30°31...
... Pressure conduit, 32 ... Control valve.

Claims (1)

[Claims] 1. A heat exchanger through which the heated fluid passes, a burner that heats the heat exchanger, a fuel pressure controller that controls the fuel supply pressure to the burner to control the amount of combustion in the burner, and a fuel pressure controller that controls the fuel supply pressure to the burner to control the amount of combustion of the burner. a pressure difference generator that generates a pressure difference; a force generator that applies the pressure of the pressure difference generator to both sides of the diaphragm through a pressure conduit and generates a force corresponding to the pressure difference; and a control unit that controls the fuel pressure controller in accordance with the force of the force generator so that the force is approximately proportional to A fuel supply control device that adjusts the proportional ratio between the heating fluid flow rate and the burner combustion amount.