KR20070086041A - Burner for a heater with improved heat shield - Google Patents

Abstract

The invention relates to a burner (10), for a heating device, in particular, for application in motor vehicles, comprising a burner nozzle (12), for the introduction of fuel and primary air, a combustion chamber (22) and a heat shield (24), between the burner nozzle and the combustion chamber, whereby the heat shield comprise openings (26), for the introduction of secondary air into the combustion chamber. According to the invention, the openings are provided with air guide elements (28, 30).

Description

Burner for a heater with improved heat shield

FIELD OF THE INVENTION The present invention relates in particular to a burner for a heater to be used for a motor vehicle, comprising a combustor nozzle for supplying fuel and first air, a combustion chamber, and a heat shield between the combustor nozzle and the combustion chamber, the heat shield being a combustion chamber. It has holes for supplying a second air into it.

Such combustors are also referred to as atomization combustors or spray combustors and are used in particular in auxiliary heaters and independent heaters for automobiles.

Especially for these combustors, there are numerous requirements with regard to reliable and large scale emission-free starting behavior and stable combustion behavior. In addition, efforts have been made to fabricate heaters that can be used at different installation locations.

With regard to the starting nature, the various operation parameters must match each other. On the one hand, it is necessary to make a relatively rich fuel-air mixture available in the starting zone while the combustor is starting, but on the other hand, it is necessary to transport the fuel from the fuel needle to the starting zone. Sufficient first combustion air is required to ensure.

The requirement of allowing different installation positions of the heater leads to problems with starting properties. In order to transfer fuel to the starting area with a small supply of first air, it has previously been allowed to direct the fuel needle with the exit hole downward, which results in mounting the entire combustor in a vertical installation position.

In order to ensure stable combustion operation of the combustor, such contradictory requirements must be met. On the one hand, good mixing of fuel and air is always required, on the other hand, in particular in the central region of the flame and during the start-up phase it is particularly important to cause excessively high temperature rates and excessively high swirling. Not desirable

It is an object of the present invention to at least partially solve the above-mentioned problems of the prior art and, in particular, to ensure low-emission starting properties with reliable and rich smoke freeness at different installation locations.

This object is achieved by the features of the independent claims.

Advantageous refinements of the invention are given in the dependent claims.

The present invention is based on a general combustor equipped with openings in the air guide member. Heat shied is basically useful for shielding the nozzle and fuel supply against the heat energy present in the combustion chamber. The second air is also supplied to the combustion space through the heat shield. This second air can be supplied in a controlled manner by providing holes in the air guide members for the second air supply so that the combustion operation can be influenced in a certain manner for both the starting operation as well as the continuous operation.

It is useful for the air guide members to be formed by tabs fabricated integrally with the heat shield and protruding in the direction of the combustion chamber. Such heat shields can be readily manufactured, for example, by forming such tabs in a v-shape with a punching tool, or by bending them out of the plane of the heat shield after or simultaneously with the punching process.

In addition, the present invention has been developed usefully in that the tabs are manufactured at different angles with respect to the surface of the heat turn and / or the radius of the heat shield. If the tabs extend almost perpendicular to the radius of the thermal debris, this conveys a strong angular momentum, while less angles relative to that radius deliver less angular momentum. Tabs that assume a small angle to the surface of the heat shield produce an air flow with a large radial component and a small axial component, while the tabs have a large tab relative to the surface of the heat shield. In the case of an angle, the axial component predominates. In this way, it is possible to direct the second air with low angular momentum to the central region of the flame formation. In this way, on the one hand the air necessary for combustion is supplied, but there is no extra angular momentum which causes an effect against the stabilization of the flame. In particular, the second air can be separated based on the alignment of the respective air guide members.

According to another embodiment, tabs are provided that are grouped at substantially the same angle with respect to the surface of the heat shield and / or the radius of the heat shield. The defined flow states in the combustion chamber are formed by the collective alignment of the tabs.

Further, according to the present invention, the combustor has a burnout zone, and the second air supplied to the exhaust zone has a higher angular momentum than the second air supplied to the starting zone. High angular momentum is required in exhausted areas. In particular, radially inside swerled backflow enhances burnout and provides a volume that can be effectively used for the combustion chamber.

The heat shield also has a hole for the ignition member to penetrate.

According to a particularly preferred embodiment of the invention, the combustor nozzle comprises a fuel needle for supplying fuel to the combustor and a first air supply for supplying combustion air to the combustor, starting the combustor by selecting the inner diameter of the fuel needle. The discharge rate of the fuel is predetermined so that fuel in the form of substantially unsprayed during the step reaches the starting zone. Reducing the inner diameter of the fuel needle compared to the fuel needle in the heaters of the prior art increases the discharge rate of the fuel equal to the fuel delivery volume. In this way, the fuel jet can reach the starting area from the discharge hole of the fuel needle at any installation position. In particular, when the amount of the first air is small, the supplied first air should have only a small amount of angular momentum, and the fuel spray which is not substantially sprayed may reach the starting region. As a result, the combustor starts reliably and clearly reduces the formation of dense smoke during startup.

The inner diameter of the fuel needle is preferably between 0.5 mm and 0.7 mm. Compared to the discharging speed for the fuel needle of the prior art in which the inner diameter is in the range of 0.8 mm, the discharging speed for the inner diameter between 0.5 mm and 0.7 mm is almost doubled or more.

It is particularly preferable that the inner diameter of the fuel needle is approximately 0.6 mm. With this internal diameter, a ejection speed of more than 0.6 m / s is possible at full load operation, ie, fuel mass flow of 0.5 kg / h, while the ejection speed is 0.8 mm. 0.35 m / s. For the corresponding selection of design properties or operating factors, the goal of substantially unsprayed jet reaching the starting area when the heater is started can also be achieved by a prior art fuel needle with an internal diameter of approximately 0.8 mm.

The starting area is advantageously made as a starting chamber in which the ignition element protrudes into it. The wall of the combustion chamber can surround the ignition member in this manner. During start-up operation, a “ballistic” fuel ejection can moisten the combustion chamber wall with the ignition member and fuel so that after they have been heated, components adjacent to the combustion chamber wall can be used as a wall vaporizer. have.

In addition, in a particularly preferred embodiment of the invention, the combustion chamber is substantially axially symmetrical, in which there is a baffle plate, the baffle plate having a given curvature in the axial direction. Because of the bending of the baffle plate, the shape of the baffle plate is independent of temperature. For flat baffle plates of the prior art, this is not a problem, among other things, since spontaneous changes in shape are possible with temperature and have a negative effect on the combustion properties of the combustor.

It is preferable that curvature exists in the direction of the exhausted region. In this way, sufficient space can be utilized in the region of the starting chamber. In addition, it was found that bending in the direction of the burnout region does not negatively affect the flow behavior in this region. In particular, the apparently swirling backflow region remains in the radially inner region of the exhausted region.

According to a preferred embodiment of the invention, the outer circumferential surface of the baffle plate partitions a plane, and the ratio between the maximum axial distance of the baffle plate and the diameter of the baffle plate from this plane is provided between 0.07 and 0.21. The most specific point of the baffle plate is preferably the substantial center of the arrangement with respect to the radial coordinates. From the plane partitioned by the outer circumferential surface of the baffle plate, this point has an axial distance partitioned by the same proportion as the diameter.

In this connection, it is particularly preferred that the ratio between the maximum axial distance of the baffle plate from the plane and the diameter of the baffle plate is approximately 0.14. For example, the round diameter of the baffle plate is approximately 40 mm, while the curvature has a value of approximately 5.7 mm.

The present invention is based on the fact that it is a novel heat shield with air guide members, in particular the combination of a novel fuel supply and a novel baffle plate can dramatically improve the operating properties of the combustor. This relates in particular to the starting properties, the stability of the combustor operation and the possibilities for the installation position of the combustor of the motor vehicle.

The invention is described in an illustrative manner with reference to the accompanying drawings, in which preferred embodiments are shown.

1 shows a sectional view of a combustor according to the invention.

2 shows a perspective view of a combustor flange with a heat shield inserted;

3 shows a perspective view of a heat shield.

<Explanation of symbols for main parts of the drawings>

10 ... Combustion 12 ... Combustion nozzle

14 Fuel needle 16 Combustion air supply

18.Starting area 20 ... Ignition member

22.Combustion chamber 24 ... Heat shield

26 holes 28 air guide member

30 Air guide member 32 Exhausted area

34 holes 36 baffle plates

38.Flame tube 40 ... Combustion pipe

42 External pipe 44 Attachment pin

46 ... Mounting pin 48 ... hole

50 ... fuel feeder 52 ... metal pipe

In the detailed description according to the preferred embodiment of the present invention, the same reference numerals denote the same or corresponding components.

1 shows a sectional view of a combustor according to the invention. The combustor 10 according to the invention has a nozzle 12 rigidly coupled to a heat shield 24. The heat shield 24, together with the combustor pipe 40 connected to the heat shield 24, partitions the combustion chamber 22. The combustion chamber pipe 40 is surrounded by an outer pipe 42 forming a combustor flange. The flame tube 38 is attached to the outer pipe 42. The connections between the heat shield 24 and the combustion chamber pipe 40 or between the combustion chamber pipe 40, the outer pipe 42 and the flame tube 38 are generally welded connections. The fuel nozzle 12 has a fuel supply 50 having a metal pipe 52 for fuel supply and a fuel needle 14 for injecting fuel into the combustion chamber 22. In addition, there are channels in the region 16 of the fuel nozzle for supplying the first combustion air to the fuel nozzle 20, the first combustion air then having the fuel nozzle 12 in the direction of the combustion chamber. Flows past the fuel needle to flow eventually along the radially widened air guide of and into the combustion chamber 22. Radial widening of the air guide can result in improved atomization due to the Venturi effect. Also within the combustion chamber 22 is a baffle plate 36 with advantageous curvature. This curvature in the direction of the burnout area 32 is beneficial because the heat-induced spontaneous shape change of the baffle plate 36 is prevented in this way. By further bending the baffle plate 36 in the direction of the burnout area 32, sufficient space for accommodating the starting chamber 18 can be utilized. The wall defining the starting chamber 18 is welded to the baffle plate 36.

2 is a diagram of a combustor flange with a heat shield inserted, and FIG. 3 is a perspective view of the heat shield. In addition, components similar to those of the combustor parts shown in FIG. 1 are given the same reference numerals. The heat shield 24 has a central hole 48 through which the fuel-air mixture that passes from the nozzle 12 and enters the combustion chamber. There is also a hole 34 arranged laterally so that the ignition member 20 penetrates. The heat shield 24 also has attachment pins 44 and 46 to which the nozzles 12 are attached. The heat shield 24 has many holes 26 through which the second air can penetrate into the combustion chamber 22. On the side of the heat shield 24 facing the combustion chamber 22 is a triangular air guide member 28, 30. These cause the dispersion of the second air based on different angles to the radius of the heat shield 24. The first group of air guide members with members partially named by reference numeral 28 are arranged at a large angle with respect to the radius of the heat shield 24, ie their arrangement substantially or substantially tangentially forms. Based on this alignment, the second air, through the corresponding holes 26, with the outlet flow direction indicated by the arrow, will overflow into the exhaust area 32 and baffle plate 36 at high angular momentum. Will pass). Such air provided with high angular momentum flows into the back of the combustion chamber 22 in the radially centered region of the exhaust area 32, ie into the area of the combustion chamber facing away from the heat shield, and then high vortex Return to the direction of the baffle plate 36 in the central region. As a result, advantageous mixing of gaseous components occurs in the exhausting region 32. In their arrangement, the second group of air guide members 30 has a smaller angle with respect to the radius of the heat shield 24. These air guide members are indicated in part by reference numeral 30. In addition, these air guide members 30 have a smaller angle than the air guide member 28 with respect to the surface of the heat shield 24. As a result, these air guide members 30 deliver the second air into the central region of the flame at low angular momentum in the outlet flow direction indicated by the second arrow, which is particularly helpful for stable combustion chamber properties.

Thus, new spray combustors can be manufactured and improved in terms of possible installation positions, starting properties, and properties in continuous operation. In addition, problems in view of the shape change of the baffle plate due to temperature-induced can be avoided.

The features of the invention have been disclosed in the foregoing detailed description, the drawings, and the claims may be important in the practice of the invention, either individually or on the basis of a combination of embodiments of the invention.

The present invention relates to a burner for a heater, in particular having a combustor nozzle for supplying fuel and first air, a combustion chamber, and a heat shield between the combustor nozzle and the combustion chamber, the heat shield into the combustion chamber. It is used in automobiles with holes for supplying second air. Such combustors are also referred to as spray combustors or spray combustors and are used in particular for auxiliary heaters and independent heaters for automobiles.

Claims (14)

Combustor nozzle 12 for supply of fuel and first air, combustion chamber 22, and apertures 26 between the combustor nozzle and the combustion chamber, for supplying second air to the combustion chamber. In a combustor for a heater to be used in an automobile having a heat shield 24 having a) Combustor for a heater, characterized in that the holes are provided in the air guide members (28, 30). The method of claim 1, And the air guide members (28) (30) are formed integrally with the heat shield and are formed by tabs protruding toward the combustion chamber (22). The method according to claim 1 or 2, And the tabs are manufactured at different angles to the surface of the heat shield and / or to the radius of the heat shield. The method according to any one of claims 1 to 3, And the tabs are grouped at an angle substantially equal to the surface of the heat shield and / or to the radius of the heat shield. The method according to any one of claims 1 to 4, The combustor has a starting region 18 and an exhausting region 32; And the second air supplied to the exhaust area (32) has a lower angular momentum than the second air supplied to the starting area (18). The method according to any one of claims 1 to 5, And the heat shield (24) further comprises a hole (34) through which the ignition member (20) can pass. The method according to any one of claims 1 to 6, The combustor nozzle 12 has a fuel needle 14 for supplying fuel to the combustor 10 and a first air supply for supplying combustion air to the combustor, By selecting the inner diameter of the fuel needle 14, the exit velocity of the fuel is predetermined so that fuel of substantially unsprayed form reaches the starting region 18 during the startup phase of the combustor 10. Combustor for heater characterized by the above-mentioned. The method of claim 7, wherein Combustor for a heater, characterized in that the inner diameter of the fuel needle (14) is between 0.5mm to 0.7mm. The method according to claim 7 or 8, And the inner diameter of the fuel needle is approximately 0.6 mm. The method according to any one of claims 5 to 9, The starting area (18) is a combustor for a heater, characterized in that it is produced as a starting chamber in which the ignition member projects into it. The method according to any one of claims 1 to 10, The combustion chamber is substantially axially symmetrical, The combustion chamber 22 has a baffle plate, And the baffle plate (36) has a curvature given in the axial direction. The method of claim 11, Combustor for the heater, characterized in that the curvature in the direction of the exhaust area (32). The method according to claim 11 or 12, wherein The outer circumferential surface of the baffle plate partitions the plane, And the ratio between the maximum axial distance of the baffle plate and the diameter of the baffle plate from the plane ranges from 0.07 to 0.21. The method of claim 13, And a ratio between the maximum axial distance of the baffle plate (36) from the plane and the diameter of the baffle plate (36) is approximately 0.14.

Images