Pump control device

Abstract

 An interface supply device (7) for controlling an electric motor (2'), comprises a pair of input terminals (7"), to which supply means (10) can be connected, and a pair of output terminals (7'), which can be connected to the supply terminals of said electric motor (2'); the device further comprises detection means (11) for generation of one or more electrical signals proportional to measurements of physical parameters external to said device (7) or of parameters of operation of said electric motor (2'), and processing and control means (8), connected to said detection means (11); said processing and control means (8) process said one or more electrical signals coming from said detection means (11) and compare them with one or more pre-set thresholds, following upon overstepping of one or more of said thresholds, said processing and control means (8) varying the supply of said electric motor (2').

Description

[0001] The present invention relates to an interface supply device for control of an electric motor.

[0002] In greater detail, the invention regards a device capable of controlling in an automatic and continuous way operation of an electric motor, and in particular of varying the r.p.m. and/or power thereof, according to the detection of physical quantities (pressure, temperature, speed, force, etc.) and/or according to a series of parameters (time, cycles, levels, alarms, etc.), which can be appropriately set.

[0003] In what follows, the description will refer to control of permanent-magnet d.c. electric motors, with particular application to the area of hydraulics and water-supply systems, but it is clearly evident that the invention is not to be considered as in any way limited to this specific use.

[0004] As is well known, currently electric motors are very widespread both in the industrial field and in the domestic field. They are used in various systems for water distribution, systems for hydraulic pumping for controlling pistons, or systems for driving vehicles.

[0005] However, electric motors require a control of the power and/or of the r.p.m. during use. There are, in fact, known and available on the market many solutions for this purpose.

[0006] If we consider, for example, an autoclave system for pumping in the water-distribution circuit inside a dwelling, the electric motor is associated to a hydraulic pump and is provided with a pressure switch and an expansion vessel. These elements enable limitation of the troublesome effects when a tap in the dwelling is suddenly opened or closed.

[0007] In particular, the pressure switch is connected to a servo mechanism, which de-activates the electric pump (assembly made up of an electric motor and a hydraulic pump) in order to maintain the pressure of the circuit below a pre-set limit to prevent any overpressure and hence any failure of the system. In this case, however, if the expansion vessel were not also added to the system, there would be the troublesome effect of continuous activations and de-activations of the electric pump and an irregular flow of water.

[0008] Furthermore, in high-pressure hydraulic circuits, it is often necessary to carry out appropriate checks on the temperature, installing servo mechanisms for modulation of the power of the electric motor.

[0009] The main problem of the solutions according to the known art is the fact that they are generally solutions exclusively suited to specific systems and circuits.

[0010] Consequently, the purpose of the present invention is to make available an interface supply device for control of electric motors that will be able to adapt parameters of operation of the electric motor itself to achieve the best conditions of use and that will be programmable and versatile.

[0011] Consequently, a specific subject of the present invention is an interface supply device for control of an electric motor, comprising a pair of input terminals, to which supply means can be connected, and a pair of output terminals, which can be connected to the supply terminals of said electric motor, said supply device being characterized in that it comprises: detection means for generation of one or more electrical signals proportional to measurements of physical parameters external to said device or of parameters of operation of said electric motor; processing and control means connected to said detection means, said processing and control means processing said one or more electrical signals coming from said detection means and comparing them with one or more pre-set thresholds, following upon overstepping of one or more of said thresholds, said processing and control means varying the supply of said electric motor.

[0012] Once again according to the invention, said processing and control means can comprise a programmable microcontroller.

[0013] Once again according to the invention, said device can comprise a connector for programming said microcontroller.

[0014] Advantageously according to the invention, said processing and control means can comprise a storage module.

[0015] Furthermore according to the invention, said detection means can comprise a pressure sensor and/or a voltage sensor and/or a temperature sensor.

[0016] Once again according to the invention, said detection means can comprise a counter for measuring the r.p.m. of said electric motor. Again according to the invention, said device can comprise user-interface means. Preferably according to the invention, said interface means can comprise one or more LEDs. Advantageously according to the invention, said device can be connected to an alarm, and, following upon overstepping of one or more of said thresholds, said processing and control means activate said alarm.

[0017] Once again according to the invention, said supply means can be of the d.c. type.

[0018] Preferably according to the invention, said supply means can comprise a battery.

[0019] Forming a further subject of the present invention is an autoclave system having at least one intake pipe connected to a storage tank filled with a liquid fluid, a delivery pipe connected to a water-supply system, said autoclave system further comprising an electric motor, a pump connected to said electric motor and designed to pump said fluid in said water-supply system, and supply means, and being characterized in that installed between said supply means and said electric motor is an interface supply device as defined above.

[0020] Once again according to the invention, said interface device can activate or de-activate said electric motor by gradually varying the r.p.m. thereof.

[0021] Once again according to the invention, said interface device can maintain the pressure of said water-supply system in a range comprised between a first threshold P_min and a second threshold P_max.

[0022] Furthermore according to the invention, said first threshold P_min can be 1.8 bar and said second threshold P_max can be 13 bar.

[0023] Advantageously according to the invention, said interface device can de-activate the supply of said electric motor if the voltage supplied by said battery rises above a first threshold V_max or drops below a second threshold V_min.

[0024] The present invention will now be described by way of non-limiting illustration, according to preferred embodiments thereof, with particular reference to the figures of the attached plate of drawings, in which:

• Figure 1 shows an autoclave system according to the known art;
• Figure 2 shows an autoclave system comprising the interface supply device forming the subject of the present invention;
• Figure 3 shows a block diagram of the interface supply device for controlling an electric motor according to the present invention; and
• Figure 4 shows a block diagram of the possible connections of the interface supply device for controlling an electric motor according to Figure 3.

[0025] With reference to Figure 1, visible therein is an autoclave system 1 according to the known art. This is normally made up of the following elements:

• an electric pump 2 (hydraulic pump and electric motor) ;
• an expansion vessel 3;
• a pressure switch 4;
• a starting relay;
• a flexible hose 5 (for connection of the electric pump to the expansion vessel); and
• a non-return valve 6.

[0026] An intake pipe (not shown in the figure) of the electric pump 2 is connected to a tank for storage of the water (not shown in the figure). A delivery pipe (not shown in the figure) is connected to the water-supply system, for example, a domestic system (showers, toilets, bathroom facilities, taps, etc.). Said water-supply system is provided also with a discharge, in this case without pressure.

[0027] Following upon electric supply of the autoclave system 1, the pressure switch 4 closes the supply circuit of the starting relay, which in turn supplies the electric motor 2'. This starts at the maximum r.p.m., pumping water into the water-supply system by the pump 2".

[0028] In the state of closing of all the water-using facilities, the water flows out into the expansion vessel 3, filling it. Once the pre-set maximum pressure P_max has been reached, the pressure switch 4 removes supply to the starting relay, which, in turn, stops the pump 2".

[0029] When a tap of the water circuit is opened, the pressure will start to drop, until the minimum value P_min at which the pressure switch 4 has been calibrated is reached. Upon overstepping of the minimum pressure threshold P_min, the electric motor 2' starts again, once again at the maximum r.p.m., and the pressure P again increases.

[0030] Consequently, from the description it emerges that:

• the electric pump 2 pumps the water into the system and increases the pressure P in the circuit;
• the pressure switch 4 starts or stops, via the starting relay (in order not to damage the electric contacts of the pressure switch), the electric pump 2; and
• the flexible hose 5 connects the expansion vessel 3 to the water-supply system and to the electric pump 2.

[0031] The expansion vessel 3 enables accumulation of a certain amount of water under pressure in order to maintain a certain pressure immediately available following upon opening of a tap. This prevents the harmful effect known as "water-hammer effect" in the water-supply system when a water-using facility is suddenly closed. In addition, simultaneously, it prevents continuous starting and stopping of the motor 2' (this, once started, remains in operation for a time that varies according to the volume of the expansion vessel 3).

[0032] The non-return valve 6 prevents the water under pressure, when the electric pump 2 stops, from flowing back into the storage tank.

[0033] As may be readily appreciated, the apparatuses provided for control of the system 1, such as the expansion vessel, the pressure switch, and the relay, are specific for the system under consideration. In other words, they cannot be applied to any other system other than the one for which they have been pre-arranged and calibrated.

[0034] Figure 2 shows an autoclave system 1' comprised in which is an interface device 7 for supply of the electric motor 2' according to the present invention.

[0035] In particular, said autoclave system 1' is made up of:

• an electric pump 2;
• an interface device 7; and
• a non-return valve 6.

[0036] It is immediately evident how the number of the components necessary for operation is very reduced. In fact, it has been possible to replace the pressure switch 4, the expansion vessel 3, the starting relay, and the flexible hose 5 with the interface device 7.

[0037] Provided hereinafter is a description of operation of the system 1'. When the interface device 7 is supplied, a pressure sensor detects the pressure of the water-supply system and, according to the value detected and the pre-set calibration parameters, will start the motor 2' of the electric pump 2.

[0038] The motor 2' is activated initially at a pre-set r.p.m. and not immediately at the maximum possible r.p.m. as in the case of traditional systems.

[0039] In particular, starting envisages that the r.p.m. N of the motor will start at a first starting value N_start, for example 1000 r.p.m., corresponding to a certain power supplied to said motor 2' through said interface device 7. The r.p.m. of the motor 2' is increased gradually of N_incr, for example, 500 r.p.m. The parameters N_start and N_incr can be modified.

[0040] Hence, gradually the motor 2' reaches the maximum r.p.m. N_max, according to the amount of water required in order to maintain a pressure of the system at a value of normal running conditions P_{water sys} generally approximately equal to 1.8/1.9 bar (modifiable parameter).

[0041] When water is no longer taken from the system, the interface device 7 reduces the r.p.m. of the electric motor, by gradually reducing the power of supply of the motor 2' until a minimum r.p.m. N_min is reached, enabling limitation of troublesome effects in the piping.

[0042] The r.p.m. N_min is maintained for a time TN_min of a few seconds. Also TN_min is a modifiable parameter.

[0043] Next, said interface device 7, by modulating the power of supply of the motor 2', will increase the r.p.m. gradually until a maximum desired pressure P_max of, for example, 3 bar is reached, so as to pressurize the system prior to arrest of the motor 2'. Once the pressure P_max has been reached, the interface device.7 stops the motor. 2' interrupting supply, and the system 1' will remain in the wait state until a water-using facility is again opened; this will cause a drop in the pressure P of the water-supply system.

[0044] When a water-using facility is opened, the pressure of the system will tend to decrease from P_max. Once a pressure P_{water sys} has been reached, in the case in point fixed at 1.8 bar, the interface device 7 starts the electric pump 2 again, by supplying the motor 2'.

[0045] The interface device 7 applied in an autoclave system, in the embodiment described in what follows is mounted inside a purposely provided plastic container and fixed on the electric motor 2' in order to contain the overall dimensions.

[0046] It should be considered that the above is not the only possibility of installation. In fact, said interface device 7 can also be set within of the electric motor 2' or housed in a spatially independent way.

[0047] The interface device 7 comprises an electronic board, on which signalling devices are present, which in the present embodiment are five LEDs (Light Emitting Diodes), which display the state of operation of the interface device 7, for example, according to the table given below:

Diode colour	Function
Green	Power-Supply
Green	Pressure OK
Yellow	Pump running
Red	No water
Flashing red	Error-Alarm-Count number of flashes

[0048] Along with the other functions, said interface device 7 performs various important tasks, amongst which:

• not enabling operation of the electric pump 2 in the absence of water (dry running), preventing any damage to the mechanical tightness of the water-supply system and of the pump 2"; in particular, if the interface device 7 does not detect the minimum pressure P_min for a pre-set time (modifiable parameters), it sets itself in the alarm condition, stopping the motor 2' and turning on a red LED;
• not enabling operation of the electric pump 2 in the case of supply voltage V_supply below or above certain thresholds V_min or V_max; in the case where V_supply exceeds V_max or drops below V_min the interface device 7 stops the pump 2" in order not to run down the batteries (not shown in the figure) any further; a signal is issued by turning on the flashing red LED.

[0049] The interface device 7 is provided also with an input for a level switch (e.g., a float, not shown in the figures), which can be used for stopping the pump 2" in the case where the water-storage tank were to reach an excessively high level.

[0050] The interface device 7 is moreover provided with an electric output for signalling a state of alarm, which can be connected to an alarm of a visual or acoustic type.

[0051] By means of the interface device 7 it is possible to manage operation of any d.c. electric motor, for example at 12, 24, 48 V with a power of up to 1000 W, and at 220 V, 50/60 Hz with a power of up to 3000 W.

[0052] Figure 3 shows a block diagram of the interface device 7. This principally comprises a central control unit 8, generally constituted by a programmable microcontroller, and a storage unit 9. The control unit 8 is connected to the electric motor 2' by means of a pair of terminals 7'.

[0053] The control unit 8 is supplied by a battery 10, to which it is connected via a further pair of terminals 7".

[0054] Said control unit 8 is moreover connected to a plurality of sensors 11 for detecting operating parameters, such as for example:

• the pressure of the system;
• the voltage of the battery 10; and
• the r.p.m. of the motor 2'.

[0055] With reference to Figure 4, it is possible to recognize all the apparatuses or devices to which the interface device 7 can be connected. Amongst these, in addition to the already mentioned motor 2', battery 10, and sensors 11, possible alarm devices 12, and level-detection devices 13 are shown, as well as a programming console 14, which can be connected by means of a connector 14' located on the interface device itself, for entering the operating thresholds for control of the motor 2' according to the parameters that can be detected by the sensors 11.

[0056] On the basis of the above description, it may be noted that the fundamental characteristic of the present invention is the possibility of controlling operation of an electric motor by detecting parameters according to programmable thresholds and according to preferred procedures.

[0057] An advantage of the present invention is the possibility of applying said device to any type of system that uses electric motors and in particular d.c. electric motors.

[0058] The present invention has been described purely by way of non-limiting illustration according to its preferred embodiments, but it is to be understood that variations and/or modifications may be made by persons skilled in the branch, without thereby departing from the corresponding sphere of protection, as defined by the annexed claims.

Claims

1. An interface supply device (7) for controlling an electric motor (2'), comprising a pair of input terminals (7'), to which supply means can be connected (10), and a pair of output terminals (7'), which can be connected to the supply terminals of said electric motor (2'), characterized in that it comprises detection means (11) for generation of one or more electrical signals proportional to measurements of physical parameters external to said device (7) or of parameters of operation of said electric motor (2'); processing and control means (8) connected to said detection means (11), said processing and control means (8) processing said one or more electrical signals coming from said detection means (11) and comparing them with one or more pre-set thresholds, following upon overstepping of one or more of said thresholds, said processing and control means (8) varying the supply of said electric motor (2').

2. The device (7) according to Claim 1, characterized in that said processing and control means (8) comprise a programmable microcontroller.

3. The device (7) according to Claim 2, characterized in that it comprises a connector (14') for programming said microcontroller.

4. The device (7) according to any one of the preceding claims, characterized in that said processing and control means (8) comprise a storage module (9).

5. The device according to any one of the preceding claims, characterized in that said detection means (11) comprise a pressure sensor and/or a voltage sensor and/or a temperature sensor.

6. The device (7) according to any one of the preceding claims, characterized in that said detection means (11) comprise a counter for measuring the r.p.m. of said electric motor (2').

7. The device (7) according to any one of the preceding claims, characterized in that it comprises user-interface means.

8. The device (7) according to Claim 6, characterized in that said interface means comprise one or more LEDs.

9. The device (7) according to any one of the preceding claims, characterized in that it is connected to an alarm (12) and, following upon overstepping of one or more of said thresholds, said processing and control means (8) activate said alarm (12).

10. The device (7) according to any one of the preceding claims, characterized in that said supply means (10) are of the d.c.-voltage type.

11. The device (7) according to any one of the preceding claims, characterized in that said supply means (10) comprise a battery.

12. An autoclave system (1') having at least one intake pipe connected to a storage tank filled with a liquid fluid, and a delivery pipe connected to a water-supply system, said system (1') further comprising an electric motor (2'), a pump (2") connected to said electric motor (2') and designed to pump said fluid in said water-supply system, and supply means (10), said autoclave system being characterized in that installed between said supply means (10) and said electric motor (2') is an interface supply device (7) as defined in any one of Claims 1 to 11.

13. The system (1') according to Claim 12, characterized in that said interface device (7) activates or de-activates said electric motor (2') by gradually varying the r.p.m. thereof.

14. The system (1') according to either Claim 12 or Claim 13, characterized in that said interface device (7) maintains the pressure of said water-supply system in a range comprised between a first threshold P_min and a second threshold P_max.

15. The system (1') according to Claim 12, characterized in that said first threshold P_min is 1.8 bar and said second threshold P_max is 13 bar.

16. The system (1') according to any one of Claims 12-15, characterized in that said interface device (7) de-activates supply of said electric motor (2') if the voltage supplied by said battery (10) rises above a first threshold V_max or drops below a second threshold V_min.

17. A device (7) and a system (1') according to any one of the preceding claims, substantially as illustrated and described herein.

Drawing