IE980661A1 - Oil-fired stove - Google Patents

Abstract

A vapourising oil stove (10) comprises a ring type wick oil burner (26), a valve (51) for supplying oil to the burner (26), and a detector (57) for detecting during start-up if an optimum temperature has not been achieved within a required time. The valve (51) is operable to shut off the fuel supply in response to a signal from the detector (57). <Figure 1>

Description

The present invention relates to an oil-fired stove, in particular an oil-fired flame effect stove.

To date, most vapourising oil stoves have used manual lighting procedures to ignite the stove, i.e. a naked flame is introduced to light the oil vapour. Even in the case of electrically ignited stoves, the heat for providing ignition is provided by the user pressing a button until a gio-plug is hot enough to ignite the oil vapour. Such an ignition system can cause potentially dangerous situations when an attempt is made to light the stove soon after it has gone out.

When a vapourising stove is lit from cold, the flame/glo-plug ignites the oil vapour that is adjacent. As a flame is established, it spreads around the burner ring and in doing so, raises the temperature in the burner area. This rise in temperature has the effect of increasing the amount of oil vapour released from the liquid oil and thus causes the burner’s inner ring to ignite.

When a stove is shut-down, the temperatures within the burner area are still high and so there is a large quantity of oil vapour present in the stove relative to when the stove is cold. This vapour will be present even after the flame has burned out, as in burning out, only the oil in the burner rings is burned. The central reservoir will still contain a quantity of oil which will continue to vapourise due to the elevated temperatures. a. co as CM Ui 0C tZ. F Q U & Σ; Q < CD Z oo Z2 22 * Z gnition is introduced at this stage, there is a serious risk of explosion. This risk is not sent when starting from cold as the amount of vapour produced gradually increases as stove temperatures gradually increase. It is therefore desirable to prevent re-starts soon Ά· 25 * L έ qfler a stove has been extinguished. g z LU O l·o LU CZ3 e present invention provides a vapourising oil stove comprising a ring type wick oil i mer, valve means for supplying oil to the burner, means for detecting during start-up if an optimum burner temperature has not been achieved within a required time with the oil supply means being operable to shut off the fuel supply in response to a signal from the temperature detection means.

Additionally, the temperature detection means is operable to detect a steady temperature rise even if the optimum burner temperature is not achieved and in which the oil supply means is operable to delay the fuel shut off for a second set time to allow the start-up period to over-run a first set time to allow for varying draught conditions.

Advantageously, the temperature detection means is operable to detect if the burner temperature falls below a specified level during normal operation and to transmit a signal to the oil supply means to shut off the fuel supply.

Advantageously, the stove includes means for detecting spillage of fuel whereby on detection of a fuel spillage by the detection means, a signal is transmitted to the oil supply means to shut off the fuel supply.

Preferably, the stove includes means to prevent re-ignition of the burner until the burner temperature drops to a specified level, whereby the burner can be safely re-ignited following a shut off of the fuel supply by either the user or the control means.

The stove of the invention uses an electronic control system to overcome the disadvantages of the prior art problem in conjunction with monitoring the performance of the stove. The safety features of the control system include the following:• If during start-up, a sufficient temperature is not achieved within the required time span, the fuel supply is shut off and the stove shut down.

• If during normal running, the temperature within the burner falls below a certain level, the stove will shut down.

• If at any stage the spillage sensor detects spillage from the draught hood, the oil supply to the stove will be cut off and the stove will subsequently shut down.

• When the stove is turned off either by the user or by the control system, the control system will not allow a re-start until the control thermocouple senses a sufficient drop in temperature. This temperature is consistent with acceptable levels of oil vapour in the burner area.

The invention will hereinafter be more particularly described with reference to the accompanying drawings, which show by way of example only, one embodiment according to the invention. In the drawings:Figure 1 is an exploded perspective view of a stove according to the invention; and Figure 2 is wiring diagram showing the main components of the control system of the stove.

Referring to Figure 1, the stove 10 which is of cast iron construction comprises a base 11 with four legs 12, two side walls 13 and 14, a rear wall 15, a front wall 16 and a hob 17. A door 18 having a glass panel 19 is fitted to the front wall 16. An air supply spin valve 20 is fitted to the bottom of the door 18. The entire outer structure of the stove is held together by six tie-rods 21 with all the joints between surfaces being sealed with adhesive gasket tape.

Within the stove 10 is a burner carrier tray 25 into which is located a ring type oil wick burner 26 which is used in conjunction with an electronic control system to automatically light the oil burner 26 to commence the heating of the stove 10. The electronic control system constantly monitors the flame output from the burner 26 and will shut the stove down if adverse conditions are encountered. The heat output settings are manually adjusted using the air supply spin valve 20.

The oil stove 10 is a room heating appliance capable of providing 4kW (13,500 Btu/h) to the room in which it is situated. There are six heat settings which give a heat output range of 1.5kW to 4kW (5,000 to 13,500 Btu/h).

The operation of the stove 10 will now be described. Oil enters the burner 26 through the burner carrier tray 25 via a 10 mm oil line. The central reservoir 27 fills first and when the oil level reaches the level of the burner ring feed ports, oil flows first to the inner ring and from there through the outer ring feed ports 28 to the outer ring. By setting the relative height of the control valve and burner base, the pre-ignition oil level is achieved in the inner and outer burner rings 30, 31. Once a sufficient oil level is present in the rings, a gio plug 32 ignites the oil vapour in the outer ring. Flame is established in the outer ring 31 first and as the stove warms up, the flame spreads to the inner ring 30. With both rings 30, 31 alight, temperatures within the stove increase causing the rings to glow and, with the use of ceramic coals (not shown), a realistic fire effect flame pattern is established.

A flue gas baffle 40 is used to provide a back pressure within the stove which is necessary to maintain an acceptable level of efficiency. The baffle 40 also directs combustion air through the burner 26 while directing air over the glass panel 19 in the door 18 to keep it soot free. The air is pulled through the spin valve 20 on the door 18 as a result of flue pull.

A draught hood 45 is positioned on the exhaust spigot 46 which in conjunction with a temperature sensor, shuts down the stove in the event of a blocked flue or severe down draughts.

The electronic control system comprises a fuel shut-off solenoid valve 51 that is linked to z microswitch 54. Two L.E.Ds 52, 53 are included on the control board 55. A flame detector 57 and spillage sensor 58 form part of the control system but are incorporated in the burner area. A glo-plug 32, temperature vent switch 59 and thermocouple 60 are also part of the control system.

The start-up period is initiated by turning the valve 51 to its maximum setting. This activates the microswitch 54 which begins the fill timer on the control board 55. This 30 period is indicated by both L.E.Ds 52, 53 lighting. After the fill time has elapsed, the gloplug 32 is energised long enough for the outer ring to ignite. The flame detector 57 will keep the red light on until it senses that the inner ring 30 has ignited. The start up time ends when the flame detector 57 senses that the stove has warmed up sufficiently. This is indicated by the yellow L.E.D. 53 going off.

If the required temperature is not achieved by this stage, one of two things can happen: (1) If the control system does not record a steady rise in temperature, it will send the stove into shut-down mode. (2) If the required temperature is not achieved but the control system does record a steady temperature rise, it will allow the start-up period to over-run the first set time to allow for varying draught conditions. If after this over-run time the required temperature is not achieved, the stove will shut down.

Once the stove has reached a stable condition, both l.e.d.s 52 and 53 are turned off. At this stage the control valve 51 can be set to give the required heat output. To turn the stove off, the valve 51 is turned off which activates the microswitch 54. The microswitch 54 sends the stove 10 into shut-down mode where the fuel shut-off solenoid valve 51 is closed and the electronic control system will not allow the stove to be re-lit until the temperature in the burner has fallen below a safety threshold.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

Claims (6)

1. CLAIMS:1. A vapourising oil stove comprising a ring type wick oil burner, valve means for supplying oil to the burner, means for detecting during start-up if an optimum burner 5 temperature has not been achieved within a required time, with the oil supply means being operable to shut off the fuel supply in response to a signal from the temperature detection means.

2. A stove as claimed in Claim 1, in which the temperature detection means is 10 operable to detect a steady temperature rise even if the optimum burner temperature is not achieved and in which the oil supply means is operable to delay the fuel shut off for a second set time to allow the start-up period to over-run a first set time to allow for varying draught conditions. 15

3. A stove as claimed in Claim 1 or Claim 2, wherein the temperature detection means is operable to detect if the burner temperature falls below a specified level during normal operation and to transmit a signal to the oil supply means to shut off the fuel supply.

4. A stove as claimed in any one of the preceding claims, in which the stove 20 includes means for detecting spillage of fuel whereby on detection of a fuel spillage by the detection means, a signal is transmitted to the oil supply means to shut off the fuel supply.

5. A stove as claimed in any one of the preceding claims, including means to prevent 25 re-ignition of the burner until the burner temperature drops to a specified level, whereby the burner can be safely re-ignited following a shut off of the fuel supply by either the user or the control means.

6. A stove as claimed in any one of the preceding claims, substantially as herein described with reference to and as shown in the accompanying drawings.