CN1469992A - Refrigeration unit with temperature sensor - Google Patents

Abstract

A refrigerating device is equipped with a temperature sensor in the form of an infrared sensor (7), for detecting an operating temperature of the device. Said infrared sensor (7) is located on a board (5) in a non-refrigerated are of the refrigerating device, together with a control circuit.

Description

Refrigeration unit with temperature sensor

The invention relates to a refrigeration device having a temperature sensor for detecting the operating temperature of the refrigeration device.

In order to detect the operating temperature, e.g. the interior temperature or the evaporator temperature, of refrigerating devices such as refrigerators, freezers or combined refrigerating units, temperature-dependent resistors are generally used which are connected via a cable harness to the control unit for regulating the refrigerating operation. A control circuit is connected.

This long-established technique has a series of disadvantages. On the one hand, the temperature-sensitive resistor must be mounted directly on the position where its temperature is to be measured. On the contrary, the control circuit that regulates the operation of a refrigerator based on the temperature measured by the temperature sensor is usually located in an uncooled outer part of the refrigeration device, in order to avoid malfunctions caused by frost on the control circuit . This forces the control circuit and the temperature sensor to be physically separated, which makes their installation cumbersome and therefore expensive.

A wiring is required to carry the measurement signal of the temperature sensitive resistance to the control circuit. Such wiring is sensitive to interference due to electromagnetic strays. In addition, the measured temperature is not necessarily the temperature of the location to be monitored, but the temperature in the temperature-sensitive resistor. In order to avoid distortions in the temperature measurement, it must therefore be well insulated from the uncooled outer regions.

Especially if such a universal temperature sensor for monitoring the temperature of the evaporator is used, such a sensor is subject to strong temperature fluctuations, which may reach temperatures of -40°C during normal cooling operation and up to +8°C, such temperature fluctuations lead to a high mechanical load on the insulation of the temperature-sensitive resistor, which can lead to failure.

The object of the present invention is to propose a refrigeration device with a temperature sensor, wherein the installation of the temperature sensor is simplified; the sensitivity of the measurement signal of the temperature sensor to electromagnetic strays is reduced; Fault.

This object is achieved by a refrigeration device according to claim 1 .

The operating temperature measured by the infrared sensor of the refrigeration unit may be an internal chamber temperature of the refrigeration unit. In this case, a black body can be arranged in the inner chamber of the cooling device, with which the infrared sensor is in line of sight contact.

The temperature of an evaporator of the refrigeration unit is also considered as the operating temperature to be measured. In this case the infrared sensor is preferably in line-of-sight contact with a surface of the evaporator facing the interior of the refrigeration device. This allows direct measurement of the temperature of those surfaces of the evaporator which are important for the cooling of the inner chamber, which is not easily achievable when measuring with a temperature-sensitive resistor, but sometimes due to heat flow from the outside. Distorts the temperature on the back side. Since the infrared sensor does not have to be arranged in direct contact with the target whose temperature is to be measured, it can be arranged next to the control circuit, especially on a small board together with the control circuit, so the control circuit The temperature sensor and the temperature sensor can be prefabricated as a structural unit and inserted together in the refrigeration device according to the invention during assembly.

Since the temperature of the infrared sensor is not decisive for the test result, it can be installed in an uncooled outer part of the refrigeration unit. In this case it is preferably separated from a measuring surface to be monitored by an infrared-transmissive window, which blocks the unimpeded inflow of heat into the interior of the refrigeration device.

If the distance between the infrared sensor and the measuring surface to be monitored by the sensor is relatively large, then preferably a lens is arranged between the two for projecting the measuring surface onto a radiation-sensitive surface of the sensor. Such a lens can in particular simultaneously form the above-mentioned window.

For other features and advantages of the present invention, please refer to the following description of the embodiments in conjunction with the accompanying drawings. The accompanying drawings show:

Fig. 1 is a schematic sectional view of a part of the housing of the refrigeration device of the present invention according to the first design of the present invention; and

FIG. 2 is a similar sectional view of a second embodiment according to the invention.

FIG. 1 shows a very simplified sectional view through the upper front corner of the housing of a refrigeration device according to the invention. The refrigerating device comprises a thermally insulated housing, wherein in FIG. 1 a front 1 and a part of a front 2 with a door 3 attached to the front can be seen.

Above the door 3 a baffle 4 is mounted on the front side 2, which can be a simple plastic molding without good thermal insulation of its own.

In the space surrounded by the baffle plate 4 and the front surface 2, a control circuit is installed on a small plate 5, and an infrared sensor 7 is installed on its surface towards the inner cavity 6 of the refrigeration device. Such an infrared sensor can detect the intensity of infrared light in different spectral ranges and from the intensity distribution allows conclusions to be drawn about the temperature of the light source. Such an infrared sensor may, for example, be of the type similar to so-called "ear thermometers" for temperature measurement of persons. Although the infrared rays from the inside of the refrigeration device are significantly weaker than the infrared rays of the human body, and have more long waves in the middle, on the other hand, the requirements for measurement accuracy when adjusting a refrigeration device are significantly lower than those for body temperature measurement. Such an infrared sensor can therefore also be considered suitable for regulation of refrigeration installations.

The small plate 5 with the control circuit is installed on the front of the refrigeration device, and the advantage of this is that a display element, such as a light-emitting diode 8, can be installed on the small plate 5, and the user can see it through the window 9 of the baffle plate 4. They thus enable the user to be assured of the desired functioning of the refrigeration device at any time conveniently. For example, a regulator for setting the setpoint temperature of the inner chamber can also be mounted directly on the small plate 5, so that it is easily accessible to the user.

The infrared sensor 7 is located opposite a window 10 made of an infrared-permeable material inserted in the front 2, through which the characteristic thermal radiation of the black body 11 mounted in the inner chamber 6 is essentially The radiation-sensitive surface of the infrared sensor 7 can be illuminated unhindered.

The temperature at a critical point of the interior chamber 6 can be measured in a targeted manner by means of the black body 11 . It is just the front upper part of the inner chamber 6, and the black body 11 is drawn here in the accompanying drawings. This part is such a position, because here is the strongest heat flow along the edge of the door 3 in the inner chamber 6. Instead, the highest temperature in the inner chamber generally results.

However, it is also possible to move the black body 11 forward, so that the infrared sensor 7 can "see" the inside of the inner chamber 6 to a certain extent through the window 10 . In thermal equilibrium, the inner chamber 6 also has the radiation properties of a black body, so that when the black body 11 is removed, the infrared sensor 7 can be used to measure the temperature averaged over the entire field of view of the infrared sensor 7 . The peculiarity of such an arrangement is that the measured values detected by the infrared sensor 7 may be "distorted" if there is a cooling object in its field of vision, which was installed in the refrigeration unit not long ago inside, and its internal temperature has not yet been shown. The infrared radiation power of an object increases with its temperature much more strongly than linearly. This "hot" cooled object can thus "illuminate" its cold surroundings to some extent. The temperature detected by the infrared sensor is in this case higher than an arithmetic mean value of the temperature which takes into account the "hot" cooling object. However, such a distortion is entirely to be expected here, since this distortion can cause the cooling power of the refrigeration unit to be increased until the heat introduced by the new object to be cooled is diffused in the inner chamber. In this way, a heating up of the interior space is reliably prevented by the newly installed relatively hot object to be cooled, without requiring expensive circuit-technical measures.

FIG. 2 shows a section similar to that in FIG. 1 through a further developed variant of the refrigeration device according to the invention. In addition to the elements of the refrigeration device already represented in FIG. 1 and described above, FIG. 2 also shows part of the back plate 13 of its housing and part of the evaporator plate 14 arranged on this back plate. In this variant, the window 10 is replaced by a lens 15 which is made of the same material as the window 10 and which can be inserted in the front side 2 of the housing in a corresponding manner.

Compared with the technical solution shown in FIG. 1 , the function of the lens 5 is to limit the field of view 16 of the lens defined by the dashed line in FIG. 2 , and only detect a limited range 17 of the evaporator plate 14 . With this arrangement, the temperature of the evaporator plate 14 can be accurately monitored transversely through the inner chamber 6 .

Since the infrared sensor 7 itself does not bear the temperature fluctuations in the evaporator plate, its service life will not be affected, and the failure of the refrigeration device during operation is avoided.

Further developments which deviate from the exemplary embodiment described above are also possible within the scope of the invention. For example, it can be considered that many infrared sensors are installed on the small plate 5, and they monitor a viewing area in the inner chamber 6 of the refrigeration device through a window of their own. Such a differential temperature monitoring enables the control circuit to distinguish, for example, an inserted object that only locally causes an increase in the temperature measurement from a general malfunction, in the latter case due to cooling failure. The temperature of the entire inner chamber 6 is increased.

Claims (10)

1. have a kind of refrigerating plant of temperature sensor of the working temperature that is used for pick-up unit, it is characterized in that this temperature sensor is a kind of infrared sensor (7).

2. by the described refrigerating plant of claim 1, it is characterized in that this working temperature is the temperature of an inner cavity chamber of refrigerating plant (6).

3. by the described refrigerating plant of claim 2, it is characterized in that infrared sensor (7) is in sight line with a black matrix (11) that is placed on inner cavity chamber (6) lining and contacts.

4. by the described refrigerating plant of claim 1, it is characterized in that this working temperature is the temperature of an evaporator (14) of refrigerating plant.

5. by the described refrigerating plant of claim 4, infrared sensor (7) is in sight line with a surface towards refrigerating plant inner cavity chamber (6) of evaporator (14) and contacts.

6. by the described refrigerating plant of one of aforesaid right requirement, it is characterized in that infrared sensor (7) is connected with the control circuit of working temperature and is close to and is arranged in this circuit next door.

7. by the described refrigerating plant of claim 6, it is characterized in that infrared sensor (7) all is arranged on the platelet (5) with this control circuit.

8. by the described refrigerating plant of one of aforesaid right requirement, it is characterized in that this temperature sensor is installed in the foreign range of a not refrigeration of this refrigerating plant, and can see through ultrared window (10,15) with surface measurements to be monitored by one and separate.

9. by the described refrigerating plant of claim 18, it is characterized in that this temperature sensor is arranged under the front baffle plate (4) of this refrigerating plant.

10. by the described refrigerating plant of one of aforesaid right requirement, it is characterized in that a kind of radiosensitive lip-deep lens (15) that surface measurements (7) are projected in this temperature sensor.