DEVICE IN AN OIL HEATING INSTALLATION

Technical field of the invention

The present invention relates to a device in an oil heating installation, whereby the device comprises an oil pump and an oil deaerator, the oil deaerator comprises at least one float chamber with at least one float, the float chamber is provided with a float valve which communicates with the outside of the float chamber, the float being intended to cooperate with the float valve, and the oil pump comprises a pump housing.

State of the art

A known problem with conventional oil deaerators and oil pumps is that the oil and air coming from the tank have first to go through the oil pump. This means that some of the air will pass through the oil burner and the oil nozzle. As many oil pumps/oil burners are sensitive to air, this is a problem which adversely affects the operation of oil heating installations.

Objects and features of the invention

A primary object of the present invention is to provide an oil pump of the kind defined in the introduction in which the air content of the oil is substantially reduced.

A further object of the present invention is to draw air-free oil from a bottom region of a first float chamber.

At least the primary object of the present invention is achieved by an oil pump having the features indicated in the independent claim 1 below. Preferred embodiments of the invention are defined in the dependent claims.

Brief description of the drawings

Preferred embodiments of the invention are described below with reference to the attached drawings, in which:

Fig. 1 depicts in section an oil pump with two drive sets which is assembled to an oil deaerator;

Fig. 2 shows how the combined oil deaerator and oil pump is disposed relative to the other components in an oil heating installation;

Fig. 3 depicts in section an oil pump with two drive sets and an oil deaerator, which oil pump and oil deaerator take the form of separate units; and Fig. 4 shows how the oil deaerator and the oil pump are disposed relative to the other components in an oil heating installation.

Detailed description of preferred embodiments of the invention The combined oil deaerator and oil pump according to the present invention depicted in Fig. 1 comprises an input shaft 1 driven by a power source (not depicted) which usually takes the form of an electric motor. The shaft 1 is supported for rotation in a pump housing 2 which accommodates a first drive set 5 (pump gearwheels) . The pump housing 2 has an inlet 27 connected to one end of a suction line 26 which has its other end connected to an oil tank 34 from which oil is drawn. A check valve 20 is disposed between the inlet 27 and the first drive set 5. In addition to the first drive set 5, a further second drive set 3 is mounted on the shaft 1. The second drive set 3 has its outlet side connected to a first outlet 19 of the pump housing 2 via a first duct 35. The pump housing 2 is assembled to a float housing 29, thereby forming a first float chamber 10 which is common to the pump housing 2 and the float housing 29. A first float 11 and a first float valve 12 with which the first float 11 cooperates are disposed in the first float chamber 10. The first float valve 12 is disposed in an upper wall of the float housing 29 and connects the first float chamber 10 to a second float chamber 30 in which a second float 13 is disposed. A second float valve 14 and a venting hole 21 are situated adjacent each other in an upper wall of the second float chamber 30.

The outlet side of the second drive set 3, i.e. the first duct 35, is connected to the first float chamber 10 by a second duct 16 with an intermediate first overflow valve 18.

The second drive set 3 has its inlet side connected to the bottom of the first float chamber 10 by a sixth duct 4.

The outlet side of the first drive set 5 is connected to the first float chamber 10 by a fifth duct 6. A third duct 15 in the form of a pipe which leads at the top into the second float chamber 30 is disposed in the first float chamber 10. It should be noted that despite the impression which may be given by Fig. 1 the duct/pipe 15 does not constitute a dividing wall in the first float chamber 10. The third duct 15 is provided, in the region of its lower end, with a membrane 8 made of elastic material and with a compression spring 9 acting upon the membrane 8. A membrane chamber 31 is defined on the side of the membrane 8 where the compression spring 9 is situated. The combined oil deaerator and oil pump comprises in addition a fourth duct 17 extending between the membrane 8 and the inlet side of the first drive set 5. A regulating valve in the form of a second overflow valve 7 is disposed between the first float chamber 10 and the fourth duct 17 and opens when a certain pressure occurs in the first float chamber 10. The free end of the fourth duct 17 abuts against the membrane 8 when the latter is in a position of rest. The membrane 8 and the second overflow valve 7 together constitute a regulating means 7, 8. The oil heating installation depicted in Fig. 2 comprises a combined oil deaerator and oil pump, which oil pump comprises two drive sets. The combined unit has been given the reference numeral 25. Oil is supplied to the unit 25 via the suction line 26 and leaves the unit 25 via an outlet duct 23 which leads to an oil nozzle 24 of an oil burner 22. The sole purpose of the second drive set 3 is to draw air-free oil from the bottom region of the first float chamber 10 and push this oil to the nozzle 24. Bottom region in this context means a lower portion of the oil deaerator. The oil pump with two drive sets 3, 5 functions as follows. When the oil burner 22 starts, the shaft 1 and the first drive set 5 (pump gearwheels) rotate. Oil is thus drawn from the oil tank 34 through the suction line 26 into the inlet 27, through the check valve 20 and into the first drive

set 5. On the outlet side of the first drive set 5, the oil is pushed into the fifth duct 6 which leads into the first float chamber 10, which will fill with oil until the first float valve 12 closes, causing the pressure to rise and the membrane 8 to press against the spring 9, which gives way, allowing the oil to pass through the fifth duct 17 and proceed back into the first drive set 5. In this case the first drive set 5 serves merely as a transfer pump maintaining a constant oil level in the first float chamber 10. The opposite side 31 of the membrane 8 communicates with the atmosphere via the duct 15, the second float chamber 20, the second float valve 14 and the venting hole 21. If for any reason the first float valve 12 does not close, the oil rises in the second float chamber 30, causing the second float 13 to rise and close the second float valve 14. In this situation, communication between the membrane chamber 31 and the atmosphere ceases and the membrane 8 will not function. To prevent the occurrence of harmful pressure in the float chambers 10, 20, the second overflow valve 7 opens, allowing oil to pass this way instead of via the membrane 8. The purpose of the check valve 20 is to prevent oil from running back to the tank 34 when the oil burner is off.

At the same time as the burner 24 starts, the second drive set 3 begins to draw oil from the bottom of the first float chamber 10 via the sixth duct 4 and into the second drive set 3. From there the oil is pushed through the first duct 35 and out through the first outlet 19 to the oil nozzle 24 via the outlet duct 23. The oil which is not consumed by the nozzle 24 passes the first overflow valve 18, which regulates the oil pressure to the nozzle 24, and proceeds via the second duct 16 into the first float chamber 10.

The oil which is consumed is drawn from the first float chamber 10, causing the pressure/level to drop somewhat in the first float chamber 10, whereupon the membrane 8 detects the pressure difference and retards the flow from the first float chamber 10 to the fourth duct 17, causing the first drive set 5 to draw more oil from the tank 34 until an equilibrium is reached between the oil being burnt and that being drawn from the tank 34.

Figs. 3 and 4 depict an alternative embodiment of the invention which comprises a separate oil pump with two drive sets 3, 5 and a specially adapted oil deaerator. Functionally, the embodiment according to Figs. 3 and 4 exhibits great similarities with the embodiment according to Figs. 1 and 2 but the oil pump and the oil deaerator are constructed as two units in case it is desired, e.g. for space reasons, to have them separated. In Fig. 4, the oil pump is denoted by ref. 25A, while the oil deaerator is denoted by ref. 55.

The oil pump depicted in Fig. 3 comprises an input shaft

I driven by a power source (not depicted) which usually takes the form an electric motor. The shaft 1 is supported for rotation in a pump housing 2 forming part of the oil pump and accommodating a first drive set 5 and a second drive set 3 (pump gearwheels) . The pump housing 2 has a first inlet 38 leading into a pump chamber 39 of the pump housing 2. The pump housing 2 also has a second inlet 48 which communicates with the inlet side of the second drive set 3 via a sixth duct 49. The outlet side of the second drive set 3 communicates with a first outlet 19 via a first duct 35. The first outlet 19 is connected by an outlet duct 23 to an oil nozzle 24 of an oil burner 22, see Fig. 4. The pump housing 2 also has a second outlet 42 which communicates with the first duct 35 via a second duct 16 and a first overflow valve 18. The inlet side of the first drive set 5 communicates with the pump chamber 39, and the outlet side of the first drive set communicates with the second duct 16 via a fifth duct 52.

The oil deaerator according to Figs. 3 and 4 comprises a float housing 29 with a first float chamber 10. A first float

II and a first float valve 12 with which the first float 11 cooperates are disposed in the first float chamber 10. The first float valve 12 is disposed in an upper wall of the float housing 29 and connects the first float chamber 10 to a second float chamber 30 in which a second float 13 is disposed. A second float valve 14 and a venting hole 21 are situated adjacent each other in an upper wall of the second float chamber 30.

A third duct 15 which leads at the top into the second float chamber 30 is disposed in the first float chamber 10. The third duct 15 is provided, in the region of its lower end, with a membrane 8 made of elastic material and with a compression spring 9 acting upon the membrane 8. A membrane chamber 31 is defined on the side of the membrane 8 where the compression spring 9 is situated. A fourth duct 17 of the float housing 29 extends between the membrane 8 and the seventh duct 36 which leads into a third outlet 50 of the float housing 29. A second overflow valve 7 is disposed between the first float chamber 10 and the seventh duct 36 and opens when a certain pressure occurs in the first float chamber 10. The free end of the fourth duct 17 abuts against the membrane 8 when the latter is in a position of rest. A fourth outlet 46 of the pump housing 29 communicates with the first float chamber 10. A third inlet 45 of the float housing 29 communicates with the seventh duct 36. A check valve 20 is disposed between the third inlet 45 and the seventh duct 36. A fourth inlet 44 of the float housing 29 communicates with the first float chamber 10.

A suction line 26 connects an oil tank 34 to the third inlet 45 of the oil deaerator. A first connecting line 43 extends between the second outlet 42 of the oil pump and the fourth inlet 44 of the oil deaerator. The direction of flow for the first connecting line 43 is from the oil pump to the oil deaerator. A second connecting line 47 extends between the third outlet 50 of the oil deaerator and the first inlet of the oil pump. The direction of flow for the second connecting line 47 is from the oil deaerator to the oil pump. A third connecting line 51 extends between the fourth outlet 46 and the second inlet 48. The direction of flow for the third connecting line 51 is from the oil deaerator to the oil pump.

The separate oil pump with two drive sets and the separate oil deaerator depicted in Figs. 3 and 4 function as follows. When the oil burner starts, oil is drawn from the oil tank 34 via the oil line 26 into the third inlet 45 of the oil deaerator and proceeds through the check valve 20, through the seventh duct 36, through the third outlet 50, through the

first connecting line 47, through the first inlet 38 and into the pump chamber 39 of the oil pump. When the oil level in the pump chamber 39 has risen to a certain level, the oil is drawn into the first drive set 5. From there the oil is pushed through the fifth duct 52, through the second duct 16, out through the second outlet 42, through the first connecting line 43, in through the fourth inlet 44 and into the first float chamber 10, causing the oil level to rise until the first float 11 closes and the function in the first float chamber 10 becomes as in the embodiment according to Fig. 1, i.e. the first drive set 5 serves merely as a transfer pump maintaining a uniform oil level in the first float chamber 10.

At the same time as the oil burner 22 starts, the second drive set 3 begins to draw oil from the bottom of the first float chamber 10 through the fourth outlet 46, through the third connecting line 51, in through the second inlet 48, through the sixth duct 49 and into the second drive set 3. There the oil is pushed through the first duct 35 and out through the first outlet 19 to the oil nozzle 24 via the outlet duct 23.

The oil which is not consumed by the oil nozzle 24 passes the first overflow valve 18, which regulates the oil pressure to the nozzle 24, and proceeds through the second duct 16, through the second outlet 42, through the first connecting line 43, through the fourth inlet 44 and into the first float chamber 10.

The oil which is consumed is drawn from the first float chamber 10, causing the pressure/level to drop somewhat in the first float chamber 10. The membrane 8 detects the pressure difference, which retards the flow from the first float chamber 10 via the fourth duct 17. The first drive set 5 then draws more oil from the tank 34 until an equilibrium is reached between the oil being burnt and that being drawn from the tank 34. Generally, in both of the embodiments described above, the arrangement with two separate drive sets 3, 5 of the oil pump causes only air-free oil from the bottom region of the first float chamber 10 to be supplied to the burner 24.

Conceivable modifications of the invention

In the embodiments described above, the regulating means of the first float chamber 10 takes the form of a membrane 8 in combination with a second overflow valve 7. It is nevertheless possible within the scope of the present invention to also conceive of the regulating means taking the form of the membrane 8 alone, in which case the second overflow valve 7 is omitted. Instead of using a regulating means in the form of a second overflow valve 7, it is also possible within the scope of the invention to conceive of using a regulating means in the form of a level valve, i.e. a valve which opens when the oil reaches a certain level in the first float chamber. Such a level valve is preferably controlled by a lever arm extending between the first float and the level valve. The level valve may also be combined with a membrane, in which case the regulating means takes the form of the membrane in combination with the level valve. Within the scope of the present invention it is also possible to conceive of the membrane 8 and associated components of the two oil deaerators described above being omitted, in which case the second overflow valve 7 alone will serve as regulating means and monitor the pressure in the oil deaerator, i.e. the second overflow valve 7 will assume the function of the membrane 8. In the two embodiments of the invention described above, the oil deaerator, whether combined with the oil pump or constituting a separate component, is provided with two float chambers each accommodating one float. Within the scope of the present invention, however, it is possible to conceive of the oil deaerator comprising only one float chamber in which at least one float is disposed. Such an embodiment of an oil deaerator is described in SE-B-341 231. The oil deaerator having only one float chamber makes no difference to what is stated above concerning the various types of regulating means described above. Each of the two oil deaerators described above is provided with a membrane. In cases where an oil deaerator with only one float chamber is provided with a membrane, the duct belonging to the membrane leads into the open air outside the oil deaerator.

Although the present invention primarily relates to the use of two separate drive sets in the oil pump, it should be noted that an oil deaerator with no membrane may also be used together with an oil pump with only one drive set. In the above description and in the claims set out below, the expression "drive set" means the gearwheel arrangement which constitutes the oil pump's raising means. These gearwheel arrangements may be constructed in various different ways. The expression "drive set" also covers these various types of gearwheel arrangement.

In the embodiments described above, the two drive sets 3, 5 are mounted on a common shaft 1, which is a practical version. It is also possible, however, within the scope of the present invention to conceive of each drive set being provided with a shaft of its own and these shafts having separate external power sources.