FIELD OF THE INVENTION

The present invention relates to a temperature sensor device for measuring a temperature of a liquid flowing through a pump. In particular, it relates to such a device with which it is possible to measure the temperature in a fast and precise way.

BACKGROUND OF THE INVENTION

Pumps are used in a wide range of applications including many where it is important to monitor the temperature of a liquid being pumped. Such monitoring will typically be related to the process for which the liquid is to be used, but it will also be necessary to ensure that the pump itself is not exposed to higher temperatures than what it can withstand. The temperature may be measured by sensors arranged in the pipes leading to or from the pump. Then the signals are to be transferred to a controller which may be provided inside the pump or as a separate unit, such as in a computer. The temperature may also be measured by sensors arranged inside the pump housing, but then the temperature is measured at a distance from the liquid being pumped, and the precision of the measurements will depend on how well the temperature is thermally conducted from the liquid to the location of the sensor being used. Furthermore, if the temperature of the liquid varies, there will typically be a delay in the measurements causing a lack of reaction that will be disadvantageous at least for some applications.

US 2011/293450 Al discloses a magnetically-driven fluid pump which includes a magnet housing that enables one or more sensors to be in indirect contact with the pumped fluid while avoiding the static seals normally required with sensors that are mounted to a fluid conduit or chamber and extend into the fluid pathway. Sensors may be used for monitoring the fluid or for feedback control of the pump. However, with such a design, the sensor may be negatively influenced, such as damaged, by operational vibrations due to the direct contact via bonding between the sensor and possibly vibrating solid parts of the pump.

Hence, an improved temperature sensor device would be advantageous.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a temperature sensor device with which it is possible to measure the temperature of a liquid flowing through a pump in a fast and precise way.

It is a further object of the present invention to provide a temperature sensor device which is designed to be retrofitted onto an existing pump without a need for re-designing the pump.

It is an object of at least some embodiments of the present invention to provide a temperature sensor device which has a high degree of robustness towards possible damage due to possible vibrations and impact during installation and operation of the pump.

It is a further object of the present invention to provide an alternative to the prior art.

In particular, it may be seen as an object of the present invention to provide a temperature sensor device that solves the above-mentioned problems of the prior art.

SUMMARY OF THE INVENTION

The above-described object and several other objects are intended to be obtained in a first aspect of the invention by providing a temperature sensor device for measuring a temperature of a liquid flowing through a pump, the temperature sensor device comprising :

- a temperature sensor, - at least one connector configured to electrically connect the temperature sensor to at least one printed circuit board of the pump, and

- a sensor cup comprising:

- a circumferential cup wall extending between a closed end and an open end of the sensor cup, the cup wall surrounding an inner cavity, the sensor cup being dimensioned and shaped for having the closed end arranged in physical contact with the rotor can of the pump during use, and

- a heat transfer medium present in the inner cavity, wherein the temperature sensor and the sensor cup are mutually arranged with the temperature sensor extending into the heat transfer medium so that during use of the temperature sensor device, the temperature sensor can measure the temperature of the liquid via the heat transfer medium.

The at least one connector and the temperature sensor may be integrally made e.g. by using a sensor probe which extends all the way to a printed circuit board with which it is to be connected. Alternatively, it may be two or more different components which are electrically connected.

In some embodiments of the invention, the temperature sensor is configured to be electrically connected to only one printed circuit board. However, the scope of protection also covers embodiments in which it is configured to be connected to two different printed circuit boards, such as one via which a signal representative of the temperature of the liquid is transferred to a control unit or other apparatus and one via which it is supplied with power. Such a control unit may be built into the pump. The at least one printed circuit board is also used for other purposes than the transfer of the signal from the temperature sensor to the control unit, such as for the control of the operation of the pump.

A rotor can is a component that houses the rotor of a pump for pumping liquid. During operation, at least a part of the liquid flows via the rotor can. Therefore, the temperature of the liquid flowing close to the sensor cup during use is directly related to the overall temperature of the liquid being pumped. Based on the measured temperature, it is possible to obtain the desired information, such as an average temperature in all of the liquid flowing through the pump. This may e.g. be determined from relationships determined by computer simulations taking the flow patterns into account and/or by physical tests.

The temperature of the liquid flowing through the rotor can is influenced by the heat generated by the motor of the pump and dissipated into the liquid. Thus, in some embodiments of the invention, an actual power of the motor is taken into account in the determination of the temperature of the liquid being pumped. Hereby the precision of the temperature of the liquid as determined from the measurements by the temperature sensor device may be improved.

An example of a model which has been found appropriate for a pump used for the initial tests of the invention is the following :

T _e = T _m - a + b + P _± - c + P _± - T _m ■ d + P ■ e

Where T _e is the temperature error, i.e. the difference between the temperature measured by the temperature sensor device and the actual temperature of the liquid being pumped; Pi is the power of the motor; T _m is the temperature of the liquid being pumped; and a-e are constants. For the pump being tested, the following constants were determined : a = 0.0075; b = 0; c = -0.0230; d = 0.0001; and e = -0.00015. For other specific pumps, the constants may be different and can be experimentally determined. By use of the above model and these constants, it was found possible to improve the precision of the temperature measurements by values in the order of 1.5 degrees Celsius.

The heat transfer medium may in some embodiments be air, but other types of material may provide a more efficient transfer of the temperature. Further examples will be explained below.

The temperature sensor may be partly or fully surrounded by the heat transfer medium e.g. depending on the type of sensor and the type of heat transfer medium used.

In some embodiments of the invention, the sensor cup is dimensioned and shaped for having the closed end extending in a liquid tight manner through an opening in the rotor can of the pump during use. This could alternatively be worded as: Temperature sensor device for measuring a temperature of a liquid flowing through a pump, the temperature sensor device comprising:

- a temperature sensor,

- at least one connector configured to electrically connect the temperature sensor to at least one printed circuit board of the pump, and

- a sensor cup comprising:

- a circumferential cup wall extending between a closed end and an open end of the sensor cup, the cup wall surrounding an inner cavity, the sensor cup being dimensioned and shaped for having the closed end extending in a liquid tight manner through an opening in a rotor can of the pump during use, and

- a heat transfer medium present in the inner cavity, wherein the temperature sensor and the sensor cup are mutually arranged with the temperature sensor extending into the heat transfer medium so that during use of the temperature sensor device, the temperature sensor can measure the temperature of the liquid via the heat transfer medium.

The opening in the rotor can may be an opening originally provided for the arrangement of a deblocking screw with which it is possible to release the rotor in case it has got stuck in a given position e.g. after a period of no operation. Many pumps are provided with such a deblocking screw and by designing the temperature sensor device for arrangement in the same opening, it is easy to retrofit a pump with a temperature sensor device according to the present invention.

By the sensor cup having a "closed end" is meant that it has no flow passage therethrough. This in combination with the liquid tight arrangement of the sensor cup in the opening in the rotor can means that the liquid in the rotor can cannot flow into the inner cavity of the sensor cup.

In presently preferred embodiments of the invention, the temperature sensor further comprises a sensor carrier comprising a body having an outer surface configured to be fastened in a desired position of the pump, wherein the temperature sensor is carried by and extending away from the body. An example of such an embodiment will be described in relation to the figures. The fastening may e.g. be by press fit, gluing, or welding.

In embodiments comprising a sensor carrier, the sensor carrier may be provided with guide elements on an outer surface, the guide elements being configured to engage with a mounting surface of the pump. Hereby it may be easier to ensure a correct mounting of the sensor carrier which also ensures that it stays in the intended location during operation and over time.

In embodiments comprising a sensor carrier, the only connection between the sensor carrier and the sensor cup as well as between the temperature sensor and the sensor cup may be via the heat transfer medium. In the same manner, for embodiments without a sensor carrier, the only connection between the temperature sensor and the sensor cup may be via the heat transfer medium. Hereby the temperature sensor is protected from possible damage that could otherwise arise due to interaction, such as impact forces, deformation, or thermal expansion, during assembly, installation, and operation of the pump.

Furthermore, there should preferably be a physical gap between the neighbouring surfaces of two components, the gap being filled with the heat transfer medium to ensure that there is no damaging interaction. The size of the gap for a given application will depend on the sizes, geometries, tolerances, expected vibrations, and possible mutual movements during use; it will therefore be determined as part of a design process.

In embodiments in which the sensor cup is dimensioned and shaped for having the closed end extending in a liquid tight manner through an opening in a rotor can of the pump during use, the sensor cup may comprise a sensor cup flange extending outwards from an outer surface of the cup wall, the sensor cup flange being configured to provide a liquid tight connection with the opening in the rotor can. The sensor cup flange is typically connected to the rotor can by welding.

The closed end of the sensor cup may be plane, curved, semi-spherical, or cone- shaped. Some examples will be shown in the figures. The shape is chosen to ensure a sufficient heat transfer between the liquid in the rotor can and the heat transfer medium. The amount of heat being transferred is related to the size of the area available for the transfer. Furthermore, a larger surface area will cause an increase in the flow rate of the liquid along the surface, which again will improve the transfer of heat.

In embodiments in which the sensor cup is dimensioned and shaped for having the closed end extending in a liquid tight manner through an opening in a rotor can of the pump during use, an outer surface of the closed end of the sensor cup may be provided with disrupting elements configured to create turbulence in the liquid flowing through the pump during use and thereby increase the heat conductivity between the liquid and the heat transfer medium. Hereby more precise measurements may be obtained.

The sensor cup may be made from a different material than the rotor can of the pump in which it is configured to be arranged. Hereby the material can be chosen for the sensor cup which material has a high heat conductivity so that the temperature measurements become as reliable as possible. The rotor can is typically made from metal, plastic, or fibre reinforced plastic. The sensor cup may e.g. be made from copper or aluminium which gives a good heat transfer capability. However, it may also be made from plastic or a polymer composite material.

In some embodiments of the invention, the at least one connector comprises at least one spring-loaded electrically conductive connector pin. In embodiments comprising a sensor carrier, the at least one connector may be an electrically conductive coating on an outer surface of the body surface electrically engagable with one or more terminals extending from the at least one printed circuit board of the pump in which it is configured to be arranged. Some examples will be shown in the figures.

In embodiments in which the sensor cup is dimensioned and shaped for having the closed end extending in a liquid tight manner through an opening in a rotor can of the pump during use, the closed end of the sensor cup may be configured to extend at least 3 mm, such as at least 5 mm, such as at least 10 mm, mm into the liquid flowing through the rotor can. The longer it extends into the liquid, the more precise measurements it may be possible to obtain. However, it should not extend so far that it risks being damaged e.g. due to mechanical damage caused by vibrations during use.

As mentioned above, the heat transfer medium may be air. However, it may alternatively be a gel, an elastomer, a paste, a liquid, or a combination thereof. A gel may be defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady state, although the liquid phase may still diffuse through this system. A paste may be defined as a thick, soft, moist substance typically produced by mixing dry ingredients with a liquid. For some types of materials mentioned, the viscosity is so low that some sealing will be necessary to ensure that it remains in the inner cavity during both installation and operation. When selecting a heat transfer medium for a given application, the parameters used in the determination will typically include the heat transfer coefficient and the viscosity. Furthermore, the elastic properties should be so that no harmful vibrations, stresses or deformations are transferred to the temperature sensor from the surrounding elements. At least for some of the materials mentioned, the elastic properties may be time and temperature dependent.

In a second aspect, the invention relates to a pump comprising :

- a temperature sensor device according to any of the embodiments as described above,

- a motor driving the pump,

- a rotor can housing a rotor of the motor,

- at least one printed circuit board to which the at least one connector of the temperature sensor device is connected, and

- a power supply.

In such a pump, an actual power of the motor during use may be taken into account in the determination of the temperature of the liquid. An example of this option was described above.

The first and second aspects of the present invention may be combined. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE FIGURES

The temperature sensor device according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

Figure 1 schematically shows an exploded view of an example of a prior art pump.

Figure 2 schematically shows two examples of how a temperature sensor device according to the present invention can be arranged in relation to a rotor can of a pump. Figure 2. a shows an embodiment in which the closed end of the sensor cup abuts an upper surface of the rotor can, and figure 2.b shows an embodiment in which the closed end of the sensor cup extends in a liquid tight manner through an opening in the rotor can.

Figure 3 schematically shows another example of a temperature sensor device according to the present invention arranged in a pump.

Figure 4 schematically shows the temperature sensor device of figure 3 removed from the pump.

Figure 5 schematically shows another embodiment of a temperature sensor device according to the present invention. Figures 5. a and 5.b show the sensor carrier before and after mounting of the temperature sensor, respectively. Figure 5.c shows the sensor carrier arranged so that the temperature sensor is located in the inner cavity of the sensor cup.

Figures 6. a to 6.d schematically show different examples of geometries of a sensor cup.

Figure 7 schematically shows an example of a sensor cup having an outer surface of the closed end provided with disrupting elements. DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 schematically shows an exploded view of an example of a prior art pump 1. The different components of which it is composed will be well-known to a person skilled in the art. The figure shows the location of the stator 2 of the motor driving the pump and the rotor can 3 housing the rotor 4 of the motor. It also shows a printed circuit board 5 to which the at least one connector of the temperature sensor device is connected when the pump 1 has been provided with a temperature sensor device that will be described in the following.

Figure 2 schematically shows two examples of how a temperature sensor device 6 according to the present invention can be arranged in relation to the rotor can 3 of a pump 1. Figure 2. a shows an embodiment in which the closed end 13 of the sensor cup 11 abuts an upper surface of the rotor can 3, and figure 2.b shows an embodiment in which the sensor cup 11 is dimensioned and shaped for having the closed end 13 extending in a liquid tight manner through an opening 21 in the rotor can 3 of the pump 1 during use. In both embodiments, the temperature sensor device 6 comprises a temperature sensor 7 and a sensor carrier in the form of a body 8 having an outer surface 9 configured to be fastened in a desired position of the pump 1. The temperature sensor 7 is carried by and extending away from the body 8. The temperature sensor device 6 comprises a connector configured to electrically connect the temperature sensor 7 to at least one printed circuit board 5 of the pump 1. In the two embodiments in figure 2, the upper end of the connector 10 is in the form of two spring-loaded electrically conductive connector pins. The part of the connector 10 extending between the connector pins and the temperature sensor 7 is not visible in this figure. The temperature sensor device 6 has a sensor cup 11 comprising a circumferential cup wall 12 extending between a closed end 13 and an open end 14 of the sensor cup 11. The cup wall 12 surrounds an inner cavity 15 in which a heat transfer medium 16 is present. The heat transfer medium 16 will typically be a gel, an elastomer, a paste, a liquid, or a combination thereof. However, the scope of protection also covers embodiments wherein air is used as heat transfer medium.

The temperature sensor 7 and the sensor cup 11 are mutually arranged with the temperature sensor 7 extending into the heat transfer medium 16 so that during use of the temperature sensor device 6, the temperature sensor 7 can measure the temperature of the liquid flowing through the pump 1 via the heat transfer medium 16. As explained above, at least a part of the liquid being pumped during use of the pump 1 flows via the rotor can 3. Therefore, the temperature of the liquid flowing close to the sensor cup 11, such as the liquid into which the sensor cup 11 extends, during use is directly related to the overall temperature of the liquid being pumped.

Figure 3 schematically shows another example of a temperature sensor device according to the present invention arranged in a pump; figure 4 schematically shows the temperature sensor device of figure 3 removed from the pump. In this embodiment, the temperature sensor 7 is connected to the printed circuit board 5 via a connector 10 comprising two connector pins of which one is for the sampling and transfer of temperature information and the other is for the supply of power. The body 8 of the sensor carrier 17 is provided with guide elements 18 on an outer surface 9, and the guide elements 18 are configured to engage with a mounting surface of the pump 1 as seen in figure 3. Hereby it may be easier to ensure a correct mounting of the sensor carrier 17 which also ensures that it stays in the intended location during operation also over time. However, the scope of protection also covers embodiments without such guide elements so that the fastening and guiding is obtained by the outer surface 9 of the body 8. The illustrated sensor cup 11 comprises a sensor cup flange 19 extending outwards from an outer surface of the cup wall 12, the sensor cup flange 19 being configured to provide a liquid tight connection with the opening 21 in the rotor can 3 as seen in figure 3. The sensor cup flange 19 is typically connected to the rotor can 3 by welding. The closed end 13 of the sensor cup 11 in figure 2 is plane, and the closed end 13 of the sensor cup Il in figures 3 and 4 is cone-shaped.

However, other shapes will also be covered as is shown in figure 6; see below.

Figure 5 schematically shows another embodiment of a temperature sensor device 6 according to the present invention. Figures 5. a and 5.b show the sensor carrier 17 before and after mounting of the temperature sensor 7, respectively. Figure 5.c shows the sensor carrier 17 arranged so that the temperature sensor 7 is located in the inner cavity 15 of the sensor cup 11. In this embodiment, the at least one connector 10 is an electrically conductive coating on an outer surface of the body 8 electrically engagable with one or more terminals extending from the at least one printed circuit board 5. The illustrated sensor cup 11 has a plane closed end 13 and a sensor cup flange 19. However, the sensor carrier 17 of figure 5 may also be used in combination with a sensor cup 11 with another shape, such as another shape of the closed end 13 and/or without a sensor cup flange 19.

In all of the illustrated embodiments, the only connection between the sensor carrier 17 and the sensor cup 11 is via the heat transfer medium 16. The advantages thereof are explained above. The exact location of the temperature sensor 7 with respect to the circumferential wall 12 of the sensor cup 11 may vary from what is shown in the figures.

Figures 6. a to 6.d schematically show different examples of geometries of a sensor cup 11. As explained above, the geometry should be chosen to ensure a sufficient heat transfer from the liquid to the heat transfer medium in the cavity 15 and thereby to the temperature sensor 7.

Figure 7 schematically shows an example of a sensor cup 11 having an outer surface of the closed end 13 provided with disrupting elements 20. Such disrupting elements 20 should be dimensioned and shaped so that they are configured to create turbulence in the liquid and thereby increase the heat conductivity between the liquid and the heat transfer medium 16 in the inner cavity 15. Hereby more reliable measurements can be ensured. The exact design for a given pump 1 and application thereof may e.g. be determined by use of computer simulations.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. The mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.