Patent Application
20120288381
This invention relates to a modulating pump for liquid, in particular for fuel oil.
For illustrative purposes, this text will make reference to a modulating pump intended for use with a fuel-oil burner. However, it is understood that the modulating pump according to the invention is not limited to this particular use.
Fuel-oil burner manufacturers have long searched for a means of adapting the power of the burners to the actual heating requirements dependent on the variations in the outdoor temperature.
Burners are known which are capable of operating at two powers referred to as low and high. Such a pump is disclosed in particular by the document EP 0 715 704. It comprises a pump with internal gearing which is connected to a fuel-oil automation unit via a line kept at constant pressure by a pressure regulator and a three-way valve device. This device optionally connects the fuel-oil automation unit to either the pressure side or the return side of the pump so as to create a modulated pressure. The valve device applies the constant pressure or the modulated pressure to the automation unit, thereby enabling the burner to operate at two power levels.
However, the pumps equipping these burners cannot be operated in an intermediate mode between high power and low power.
Modulating burners are likewise known for medium and high powers, e.g., from 1,000 to 30,000 kW, the fuel-oil spraying power of which is regulated continuously by acting on an adjusting screw of a pressure regulator. The document FR 2 241 746 describes such a burner. However, this type of regulation is not suited to low-power burners, due the cost thereof and to the overall dimensions of same.
An electronically modulating pump is also known, such as the one described in European Patent EP 0 202 714, comprising a pump body with an internal chamber, an intake channel, a discharge line provided with a one-way valve, a coil arranged around a first portion of the pump body and a partially magnetisable piston housed inside said chamber and held in one position by a spring. By increasing the voltage at the coil terminals, the piston moves under the effects of the magnetic field, and the fluid is discharged. By controlling the voltage frequency of the coil, the discharge volume of the pump is varied. However, in this case, only the volume of fluid displaced is regulated and not the pressure.
The purpose of the invention is to easily enable a modulating pump to be operated continuously between a minimum pressure and a maximum pressure. By continuous operation it is understood to mean that the outlet pressure of the liquid can be controlled at any set pressure, between the minimum pressure and the maximum pressure.
The invention is based on the use of an electromagnetic pump arranged in a modulating pump and on an electric control device for regulating the travel of the piston of this electromagnetic pump.
The applicant has indeed observed that the pressure of the pressure of the liquid at the outlet of the modulating pump is a nearly linear function of the voltage of the electrical control signal applied to the electromagnetic pump.
Thus, the object of the invention is a modulating liquid pump comprising a inlet port for receiving a liquid and an outlet port for delivering said liquid, an electromagnetic pump arranged between the inlet port and the outlet port and comprising a piston for pumping said liquid, a means of regulating the pressure of the liquid, said modulating pump being characterised in that said regulating means is of the electric type and is capable of regulating the travel of said piston according to an electrical setpoint signal.
The piston travel is advantageously controlled by the voltage level of the electrical setpoint signal.
According to a preferred embodiment, the regulating means is designed to apply a modulated electrical voltage signal to an excitation winding of the electromagnetic pump.
In particular, the regulating means is designed to receive an alternating electrical voltage signal and may comprise a means of rectifying this signal, e.g., a diode bridge if it is desired to rectify the negative alternations, or a diode if it is desired to simply eliminate the negative alternations.
According to one particular embodiment, the regulating means is capable of receiving an alternating electrical signal at a frequency of 50 Hz or 60 Hz.
The modulating pump advantageously comprises an anti-backflow device for the liquid between the inlet port and the outlet port.
In particular, the anti-backflow device can include an intake valve arranged upstream from the electromagnetic pump and a discharge valve arranged downstream from the electromagnetic pump.
According to one preferred embodiment, the modulating pump includes an additional pumping means arranged between the inlet port and the electromagnetic pump.
This additional pumping means is advantageously of the gear pump type.
The modulating pump can preferably include a means of regulating the minimum pressure and/or the maximum pressure of the liquid.
The invention will be better understood in light of the following description, which is made for illustrative and non-limiting purposes, with reference to the single appended drawing in which a schematic representation has been shown of a modulating pump according to the invention for supplying a fuel-oil nozzle.
The modulating pump 2 includes an inlet port 4 intended to be connected to a fuel-oil tank 6 and an outlet port 8 intended to be connected to a nozzle 10.
An electromagnetic pump 12 is arranged between the inlet port and the outlet port. This electromagnetic pump 12 conventionally includes an excitation winding 14, which is intended to be powered by an electrical control signal, a cylindrical armature 16 linked with a pump piston 18 and a compression spring 20. The piston slides inside a cylinder 22 which communicates with the intake via an intake valve 24 and with the discharge via a discharge valve 26.
The applicant observed that, when the supply voltage on the excitation winding 14 decreases, thereby resulting in a reduction in the travel of the piston 18, the pressure of the fuel oil likewise decreases in the modulating pump, and does so almost linearly.
More precisely, the supply voltage determines the piston travel, and consequently the flow rate of the fuel oil pump by the piston and thus the pressure of the fuel oil at the outlet port 8.
This supply voltage is a modulated voltage for driving the piston in a back-and-forth movement. It is provided with a regulating means 28 which receives an electrical setpoint signal Vc. The setpoint signal, for example, is derived from an alternating voltage signal coming from the electrical network at 50 Hz or 60 Hz, and the voltage of which is adjusted according to the desired fuel-oil pressure.
In the embodiment shown, the rectifying means 30 is a diode, which eliminates the negative alternations of the signal Vc. It would likewise be possible to rectify the negative alternations by means of a diode bridge. Finally, in certain applications, it is possible to apply the alternating signal directly to the excitation winding, if the frequency of the alternating signal is chosen to be sufficiently low to enable the piston to accomplish its back-and-forth movement thereof with the desired amplitude, despite its inertia.
In certain applications, the electromagnetic pump 12 may have intake capacity which alone is insufficient to enable proper operation of the modulating pump 2, in particular when the fuel-oil tank 6 is distant from the modulating pump 2, for example, when this distance is several meters. In this case, the modulating pump 2 advantageously includes an additional pump 28, e.g., such as a gear pump, which is arranged upstream from the electromagnetic pump and which is intended to supplement the low intake capacity of the electromagnetic pump.
The modulating pump likewise further includes a minimum pressure regulator 34 and a maximum pressure regulator 36, upstream and downstream from the electromagnetic pump, respectively, these regulators also being connected to a discharge line 18 terminating in the tank 6.
As shown, on the discharge side of the electromagnetic pump 12, it may further include a pressure sensor 38, a hydro-pneumatic accumulator 40, for smoothing out the fluctuations in pressure due to the back-and-forth movement of the piston, and a solenoid safety shut-off valve 42.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0705462 | Jul 2007 | FR | national |
The present application is a continuation of U.S. patent application Ser. No. 12/670,845, which is the U.S. National Stage of International Patent Application PCT/FR2008/001107, filed on Jul. 24, 2008. Through the '845 application the present application claims priority to French Patent Application 0705462 filed on Jul. 26, 2007. Each of the aforementioned applications are encorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12951715 | Nov 2010 | US |
| Child | 13104934 | US | |
| Parent | 12670845 | US | |
| Child | 12951715 | US |
