DEVICE FOR HEAT DISPENSING AND USE OF SUCH A DEVICE

Description

[0001] The present invention relates to a heat dissipation device comprising a heat source, a heat sink, and a heat-conducting element. The invention further relates to the use of such a heat dissipation device in a video endoscope.

[0002] In medical technology, monitoring and controlling temperature and heat, known as thermal management, presents a major challenge, especially with surgical instruments. Electrical components and the necessary lighting generate waste heat in confined spaces, which can only be dissipated with considerable design effort due to the limited space.

[0003] US 2017 / 0258309 A1 discloses an endoscopic instrument with a heat-generating component that is thermally coupled to a heat sink via a movable contact structure. The movable contact structure accommodates the relative movement between the heat conductor and the heat sink in order to maintain the thermal coupling between these elements and to prevent damage to such thermal coupling when the instrument is exposed to elevated temperatures, for example, during autoclaving.

[0004] US 3,391,728 discloses a heat source and a heat sink separated by liquid metal contained in a sealed housing which includes a bellows and contacts the heat source and the heat sink, and means which respond to the temperature of the heat source to physically control the pressure on the liquid metal, whereby a reduced pressure causes the liquid heat conductor to be moved away from the interface between the heat source and the heat sink.

[0005] The object of the present invention is to provide a heat dissipation device that ensures reliable alignment of several electronic components relative to one another, even in confined spaces. Furthermore, a corresponding application is to be demonstrated.

[0006] According to a first aspect of the invention, the problem is solved by a device for heat dissipation comprising a heat source, a heat sink and a heat conducting element, wherein the heat conducting element carries heat energy from the heat source to the heat sink along a heat conduction path, and wherein the heat conducting element is arranged at the heat source and the heat sink in such a way that a) a first cross-sectional area between the heat source and the heat conducting element and / or a second cross-sectional area between the heat conducting element and the heat sink increases, and / or b) the length of the heat conduction path decreases.

[0007] In connection with the invention, the inventors recognized that there are particular challenges involved in dissipating heat from two components that need to be positioned precisely relative to each other. With known devices, heat dissipation can be achieved by removing heat from both components, but it is not guaranteed that the components will remain at approximately the same temperature. Such a temperature difference can arise, for example, if the heat flow from the first component (the heat source) to a corresponding heat sink differs from the heat flow from the second component to the heat sink. Furthermore, it is possible that the two components, even if identical in construction, heat up differently. This presents a new challenge, especially for multi-channel endoscopes or exoscopes, where the optimal alignment and adjustment of the two optical channels relative to each other is crucial.

[0008] A special feature of the invention is that heat dissipation is controlled by a passive design. This utilizes the physical principle that the heat flow between a heat source and a heat sink is greater the larger the cross-sectional area A of the heat path between the heat source at temperature T1 and the heat sink at temperature T2, and / or the shorter the length d of the heat path. This physical principle is described by the following formula: Q ˙ = α ⋅ A d ⋅ T 1 − T 2

[0009] In this context, the cross-sectional area should be understood specifically as the effective cross-sectional area, and the length specifically as the effective length. This means that the cross-sectional area and / or the length that influences the heat flow according to the formula mentioned above should be considered.

[0010] Since the device can be implemented using only passive elements, it is particularly suitable for use in confined spaces. Furthermore, the absence of active components allows for exceptionally long periods of trouble-free operation. It is, of course, possible to equip the device with additional active components for monitoring and control, such as a temperature sensor or a temperature controller for the heat sink. However, for certain applications, the fact that the passive design alone can provide temperature control is considered advantageous.

[0011] The temperature control works in principle as follows: If the temperature at the heat source rises, the heat transfer element also heats up. The physical properties of the heat transfer element, including its spatial configuration, are chosen such that its physical changes either increase the cross-sectional area of ​​the heat path or shorten the effective length of the heat path. Increasing the cross-section and / or shortening the length of the heat path leads to an increased heat flow from the heat source to the heat sink. This slows down, prevents, or reverses further heating of the heat source.

[0012] When the heat source cools down, the heat transfer element also cools down. Due to its physical change, the cross-section of the heat transfer path decreases and / or the length of the heat transfer path increases. This reduces the heat flow from the heat source to the heat sink. In this way, further cooling of the heat source can be slowed down, prevented, or even reversed into heating.

[0013] Ideally, the materials used and the physical dimensions are chosen so that the heat-conducting element reacts even to slight temperature fluctuations. This makes it possible to keep the temperature of the heat source at least approximately constant or within a specified tolerance range. Since another component can, in principle, be cooled with the same device, heat dissipation from the first component occurs independently of the cooling of the second component. However, the device ensures that both components are cooled to at least approximately the same temperature.

[0014] In some designs, temperature control can be achieved by selectively utilizing expansion due to temperature changes. This temperature control maintains the temperature in components requiring precise positioning at a specific temperature or within a specific temperature range. Thus, changes in length due to temperature fluctuations, which could alter the positioning or adjustment of these components, can be reduced or prevented.

[0015] In some embodiments, the heat-conducting element rests flat against the heat source and / or heat sink. Preferably, one surface of the heat-conducting element rests against a surface of the heat source. In particular, the surface of the heat-conducting element is then arranged to slide over the surface of the heat source, with the two surfaces remaining in physical contact even during temperature changes.

[0016] The task is now completely solved.

[0017] In a preferred embodiment, the heat conducting element has a heat pipe or is permeated by a fluid to increase heat dissipation.

[0018] This design allows the heat flow from the heat source to the heat sink to be increased.

[0019] In a further advantageous embodiment, the heat source has a first recess in which a first section of the heat-conducting element is arranged, or the heat-conducting element has a first recess in which a first section of the heat source is arranged.

[0020] This design allows for a structurally simple arrangement of the heat source and the heat-conducting element in such a way that this contact is maintained even under temperature changes. The heat-conducting element preferably expands along the depth of the recess, while a continuous surface contact between the heat-conducting element and the heat source is maintained at the sides of the recess. The first recess is preferably elongated, particularly in the shape of a prism, a cylinder, or a cuboid.

[0021] In a further advantageous embodiment, the heat sink has a second recess in which a second section of the heat-conducting element is arranged, or the heat-conducting element has a second recess in which a second section of the heat sink is arranged.

[0022] As previously described regarding the first recess in the interaction between the heat source and the heat conducting element, this design also offers a good way to ensure continuous physical contact between the heat conducting element and the heat sink, even with changing temperatures.

[0023] In a further advantageous embodiment, the second recess is guided through the heat sink and the heat conducting element in the second recess is guided through the heat sink.

[0024] In this design, the heat-conducting element can also slide across the inner surface of the heat sink recess. Additionally, the heat-conducting element can now be attached to a support at its end facing away from the heat source.

[0025] In a further advantageous embodiment, the heat source, the heat sink and the heat conducting element are arranged along a straight line, in particular along a common longitudinal center axis.

[0026] This design makes it easy to establish a physical interaction between the heat source, the heat sink, and the heat-conducting element. In particular, it can be achieved that an expansion of the heat source leads to a shortening of the heat-conducting element and / or a shortening of the heat source leads to an expansion of the heat-conducting element.

[0027] In a further advantageous embodiment, the heat source, the heat sink and the heat conducting element are arranged within a housing, wherein a side of the heat source facing away from the heat conducting element and / or a side of the heat sink facing away from the heat conducting element is arranged on the housing.

[0028] This design provides a support for the heat source and / or the heat sink. In this way, a fixed point can be created for the heat source and / or the heat sink. Therefore, the effect of a change in the length of the heat source on the heat-conducting element can be precisely controlled.

[0029] In a further advantageous embodiment, an image sensor is formed on the side of the heat source facing away from the heat-conducting element. This image sensor has a viewing axis that extends out of the housing through an opening in a wall of the housing. This embodiment allows the image sensor to be kept at a substantially constant temperature or within a specific temperature range. As a result, the viewing axis of the image sensor remains essentially constant. Furthermore, if a second image sensor forms part of the heat source, or if a second image sensor forms a second heat source of a second such device, the first and second image sensors undergo identical temperature control. This allows the first and second image sensors to be kept at essentially the same temperature, even if they emit different amounts of heat.

[0030] In a further advantageous embodiment, the device also has a control element that absorbs heat energy from the heat source and exerts an increasing pressure on the heat-conducting element as the temperature rises.

[0031] This design allows for a reduction in the length of the heat transfer path between the heat source and the heat sink. This is achieved by the pressure exerted by the control element, which compresses the heat transfer element. Shortening the heat transfer path increases the heat flow. In this way, heating of the heat source is slowed down, suppressed, or reversed into cooling. When the heat source cools, the control element also cools down, and the pressure on the heat transfer element is reduced. This causes the heat transfer element to expand towards its original shape, thus increasing the length of the heat transfer path. This, in turn, slows down, suppresses, or reverses the cooling of the heat source.

[0032] In a further advantageous embodiment, the device has a lever with a first lever arm and a second lever arm, wherein the control element exerts an increasing pressure on the first lever arm as the temperature increases, so that the second lever arm exerts pressure on the heat conducting element via the heat sink.

[0033] This design makes it possible to increase the pressure that the control element indirectly exerts on the heat-conducting element. In preferred embodiments, the ratio of the second length of the second lever arm to the first length of the first lever arm is at least 1, preferably at least 1.5, particularly preferably at least 2, and especially at least 2.5.

[0034] In a further advantageous embodiment, the device also has a control element that absorbs heat energy from the heat source, and at least a section of the control element moves towards the heat-conducting element as the temperature increases, or pressure on the heat-conducting element is increased.

[0035] In this design, the control element acts directly on the heat-conducting element. This simplifies the construction.

[0036] In a further advantageous embodiment, the control element is designed as a first strip and has a counter element which is fixedly arranged as a second strip on the control element, wherein the counter element consists of a material that has a different coefficient of thermal expansion than the control element, wherein the control element is arranged with the counter element such that the control element presses against the heat-conducting element with increasing pressure as the temperature increases.

[0037] This design utilizes a physical principle similar to that of a bimetallic strip. Since the counter-element has a different coefficient of thermal expansion, and remains essentially unchanged, particularly within the operating temperature range of the device, the rigid connection between the control element and the counter-element leads to deformation of the control element, specifically curvature. This resulting force is used to exert pressure against the heat-conducting element. The pressure compresses the heat-conducting element, thus shortening the heat conduction path. In advantageous embodiments, the control element and the counter-element form a bimetallic strip.

[0038] In a further advantageous embodiment, the heat conducting element is designed as a thermal pad, the thickness of which decreases with increasing pressure through the control element.

[0039] This design is very robust. The thermal pad can be compressed under increasing pressure and expands back to its original shape when the pressure is released.

[0040] In a further advantageous embodiment, the heat-conducting element has a first comb-like element and a second comb-like element which are complementary to each other and comb together, wherein the first comb-like element is arranged at the control element and the second comb-like element is arranged at the heat sink, wherein the first comb-like element and the second comb-like element slide further into each other when the pressure increases through the control element.

[0041] This design allows us to take advantage of the fact that the cross-sectional area of ​​the heat conduction path increases as the comb-like elements are pushed further into each other or as they comb together.

[0042] According to a further aspect of the invention, a video endoscope with a device according to one of the preceding claims is shown, wherein the heat source comprises an image sensor. In some preferred embodiments, the heat source is configured as an image sensor. In further preferred embodiments, the heat source is configured as a first image sensor and a second image sensor, or the heat source comprises a first image sensor and a second image sensor. In other preferred embodiments of the video endoscope, the video endoscope, in addition to the aforementioned first device, comprises a second device in which the heat source is configured as a second image sensor.

[0043] A third aspect demonstrates the use of a previously described device for heat dissipation in a video endoscope.

[0044] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0045] An embodiment of the invention is shown in the drawings and is explained in more detail in the following description. The drawings show: Fig. 1 shows a first embodiment of a device at a lower temperature; Fig. 2 shows the first embodiment at a higher temperature; Fig. 3 shows a second embodiment of a device; Fig. 4 shows a third embodiment of a device; Fig. 5 shows a fourth embodiment of a device at a lower temperature; Fig. 6 shows the fourth embodiment at a higher temperature; Fig. 7 shows a fifth embodiment of a device at a lower temperature; Fig. 8 shows the fifth embodiment at a higher temperature; Fig. 9 shows a sixth embodiment of a device at a lower temperature; Fig. 10 shows the fifth embodiment at a higher temperature; Fig. 11 shows a first embodiment of a video endoscope; Fig. 12 shows a second embodiment of a video endoscope; and Fig. 13 shows a third embodiment of a video endoscope.

[0046] Fig. 1 Figure 1 shows a first embodiment of a device 10 for heat dissipation with a heat source 12, a heat sink 14 and a heat conducting element 16. The heat conducting element carries heat energy E from the heat source 12 to the heat sink 14 along a heat conduction path 18.

[0047] The heat conducting element 16 is arranged at the heat source 12 and the heat sink 14 in such a way that, with increasing temperature of the heat conducting element 16, it changes physically in such a way that at least one of the following two changes occurs: a) a first cross-sectional area A between the heat source increases and / or a second cross-sectional area between the heat conducting element 16 and the heat sink 14 increases (not shown here); b) a length d of the heat conduction path 18 decreases.

[0048] The heat source 12 has a first recess 20 in which a first section 22 of the heat conducting element 16 is arranged.

[0049] In this first embodiment, the main focus is on the fact that the first cross-sectional area A increases with rising temperature. In this first embodiment, the heat-conducting element 16 is connected to the heat sink 14 via an optional thermal pad 24.

[0050] Fig. 2 This illustrates the situation when, in the first embodiment, according to Fig. 1 The temperature of the heat source 12, and consequently the temperature of the heat-conducting element 16, increases. It can be seen that the heat-conducting element 16 has extended into the recess 20 of the heat source 12. Physical, planar contact between the heat-conducting element 16 and the heat source 12 continues.

[0051] Since the first cross-sectional area A between the heat source 12 and the heat conducting element 16 has now increased, a greater heat flow also arises between the heat source 12 and the heat sink 14. In other words, the heat source 12 is now cooled more effectively.

[0052] Fig. 3 Figure 10 shows a second embodiment of the device. Here and in the following, reference numerals already introduced for the same or functionally similar elements are used again and are not explained again.

[0053] In the second embodiment, the heat-conducting element 16 has a heat pipe 26 to increase heat dissipation. Alternatively, the heat-conducting element 16 can also be permeated by a fluid (not shown). Here, the heat sink 14 has a second recess 28 in which a second section 30 of the heat-conducting element 16 is arranged. Specifically, the second recess 28 extends through the heat sink 14, and the heat-conducting element 16 is guided through the heat sink 14 in the second recess 28.

[0054] Unlike the first embodiment, the heat-conducting element 16 here does not have a heat-conducting pad 24. Instead, the heat-conducting element 16 is arranged here on a static support 32, which is to be understood as remaining stationary even in the event of a temperature change with respect to the heat source 12, the heat sink 14 and the heat-conducting element 16.

[0055] Fig. 4 Figure 1 shows a third embodiment of the device 10, wherein the heat source 12, the heat sink 14 and the heat conducting element 16 are arranged along a straight line, in particular along a common longitudinal center axis 34. The heat source 12, the heat sink 14 and the heat conducting element 16 are arranged within a housing 36, wherein a side 38 of the heat source 12 facing away from the heat conducting element 16 and / or a side 40 of the heat sink 14 facing away from the heat conducting element 16 is arranged on the housing 36.

[0056] The thermal interface element 16 is designed as a compressible thermal pad. When the heat source 12 heats up and expands, it compresses the thermal interface element 16, thus shortening the length d of the heat path 18. This increases the heat flow from the heat source 12 to the heat sink 14, resulting in greater cooling of the heat source 12 as the temperature rises. Conversely, when the heat source 12 cools and contracts, the thermal interface element 16 expands again, increasing the length d of the heat path 18. This decreases the heat flow from the heat source 12 to the heat sink 14, resulting in less cooling of the heat source 12 as the temperature falls.

[0057] In this third embodiment, an image sensor 42 is formed on the side 38 of the heat source 12 facing away from the heating element 16. The image sensor 42 has a viewing axis 44 which is directed out of the housing 36 through an opening 46 in a wall 48 of the housing 36.

[0058] Fig. 5 Figure 1 shows a fourth embodiment in which the device 10 further comprises a control element 50 that absorbs heat energy from the heat source 12 and exerts increasing pressure on the heat-conducting element 16 as the temperature rises. As already explained, this causes the elastic heat-conducting element 16 to be compressed as the temperature rises, thus shortening the length d of the heat-conducting path 18.

[0059] In the fourth embodiment, a lever 52 is used for this purpose, which has a first lever arm 54 and a second lever arm 56. Here, the lever 52 is arranged at a lever abutment 58. As the temperature rises, the control element 50 exerts an increasing pressure on the first lever arm 54, so that the second lever arm 56 exerts pressure on the heat-conducting element 16 via the heat sink 14. The pressure is transmitted, by way of example, via a rigid rod 60.

[0060] Fig. 6 Figure 4 shows the situation in the fourth embodiment when the heat source 12 has heated up and the control element 50 has expanded as a result. It can be seen that the control element 50 has pressed against the first lever arm 54, which in turn causes the second lever arm 56, via the rod 60, to push the heat sink 14 towards the heat source 12. Due to the pressure, the heat-conducting element 16 was compressed, thus shortening the length d of the heat-conducting path 18.

[0061] Fig. 7 Figure 1 shows a fifth embodiment in which the device 10 further comprises a control element 62 which absorbs heat energy from the heat source 12 and at least a section of the control element 62 moves towards the heat conducting element 16 as the temperature increases or increases pressure on the heat conducting element 16.

[0062] In this fifth embodiment, the control element 62 is designed as a first strip 64 and also has a counter element 66, which is fixedly arranged as a second strip on the control element 62. The counter element 66 is made of a material that has a higher coefficient of thermal expansion than the control element 62. The control element 62 is arranged with the counter element 66 such that, with increasing temperature and pressure, the control element 62 presses against the heat element 16.

[0063] A reverse arrangement is also possible, in which the positions of control element 62, i.e., the first strip 64, and the counter element 66 are interchanged. The counter element 66 then consists of a material that has a lower coefficient of thermal expansion than the control element 62, for example, carbon.

[0064] Fig. 8 Figure 5 illustrates the situation in the fifth embodiment when the temperature of the heat source 12 has increased and the control element 62 has compressed the heat-conducting element 16. In this embodiment, the heat-conducting element 16 is preferably designed as an elastic thermal pad whose thickness decreases with increasing pressure from the control element 62.

[0065] Fig. 9 A sixth embodiment is shown, in which a control element 62 is again connected to a counter element 66, as in Fig. 7 described, used.

[0066] In the sixth embodiment, the heat-conducting element 16 has a first comb-like element 68 and a second comb-like comb element 70, which are complementary to each other and interlock. The first comb-like element 68 is arranged on the control element 62, and the second comb-like element 70 is arranged on the heat sink 14. As the pressure through the control element 62 increases, i.e., as the temperature of the heat source 12 increases, the first comb-like element 68 and the second comb-like element 70 slide further into each other.

[0067] Fig. 11 Figure 1 shows a first embodiment of a video endoscope 80. A heat source 12, which has an image sensor 42, a heat sink 14 and a heat conducting element 16 are arranged in a housing 36.

[0068] Fig. 12 Figure 1 shows a second embodiment of a video endoscope 80, wherein the heat source 12 has a first image sensor 42 and a second image sensor 42'.

[0069] Fig. 13 Figure 1 shows a third embodiment of a video endoscope 80, which has a first heat source 12 with an image sensor 42 and a second heat source 12' with a second image sensor 42'. In addition to the first heat-conducting element 16, a second heat-conducting element 16' is also shown.

Claims

1. Apparatus (10) for heat dissipation, comprising a heat source (12), a heat sink (14) and a heat conducting element (16), wherein the heat conducting element guides heat energy (E) along a heat conducting path (18) from the heat source to the heat sink, and wherein the heat conducting element (16) is arranged on the heat source (12) and on the heat sink (14) in such a way, and changes physically as the temperature of the heat conducting element (16) increases in such a way that a) a first cross-sectional area (A) between the heat source (12) and the heat conducting element (16) and / or a second cross-sectional area between the heat conducting element (16) of the heat sink (14) increases, and / or b) the length (d) of the heat conducting path (18) becomes shorter.

2. Apparatus according to claim 1, wherein the heat conducting element (16) has a heat pipe (26) or is passed through by a fluid, in order to increase heat dissipation.

3. Apparatus according to either of the preceding claims, wherein the heat source (12) has a first recess (20) in which a first portion (22) of the heat conducting element (16) is arranged, or the heat conducting element has a first recess in which a first portion of the heat source is arranged.

4. Apparatus according to any of the preceding claims, wherein the heat sink (14) has a second recess (28) in which a second portion (30) of the heat conducting element (16) is arranged, or the heat conducting element (16) has a second recess in which a second portion of the heat sink (14) is arranged.

5. Apparatus according to claim 4, wherein the second recess (28) is guided through the heat sink (14) and the heat conducting element (16) is guided through the heat sink (14) in the second recess (28).

6. Apparatus according to any of the preceding claims, wherein the heat source (12), the heat sink (14) and the heat conducting element (16) are arranged in a straight line, in particular along a common longitudinal central axis (34).

7. Apparatus according to any of the preceding claims, wherein the heat source (12), the heat sink (14) and the heat conducting element (16) are arranged within a housing, wherein a face (38) of the heat source (12) facing away from the heat conducting element (16) and / or a face (40) of the heat sink (14) facing away from the heat conducting element (16) is arranged on the housing (36).

8. Apparatus according to claim 7, wherein an image sensor (42) is formed on the face (38) of the heat source (12) facing away from the heat conducting element (16), which image sensor has a visual axis (44) which is directed out of the housing through an opening (46) in a wall (48) of the housing (36).

9. Apparatus according to any of the preceding claims, wherein the apparatus (10) further has a control element (50) which absorbs heat energy from the heat source (12) and exerts increasing pressure on the heat conducting element (16) as the temperature increases.

10. Apparatus according to claim 9, wherein the apparatus (10) comprises a lever (52) having a first lever arm (54) and a second lever arm (56), wherein the control element (50) exerts increasing pressure on the first lever arm (54) as the temperature increases, so that the second lever arm (56) exerts pressure on the heat conducting element (16) by means of the heat sink (14).

11. Apparatus according to any of claims 1 to 8, wherein the apparatus (10) further comprises a control element (62) which absorbs heat energy from the heat source (12) and, as the temperature increases, at least a portion of the control element (62) moves toward the heat conducting element (16) or increases pressure on the heat conducting element (16).

12. Apparatus according to any of claims 9 to 11, wherein the control element (62) is designed as a first strip (64) and has a counterpart element (66) which is fixedly arranged as a second strip on the control element (62), wherein the counterpart element (66) is made of a material which has a different heat expansion coefficient than the control element (62), wherein the control element (62) is arranged together with the counterpart element (66) in such a way that the control element (62) presses against the heat conducting element (16) with increasing pressure as the temperature increases, and the heat conducting element (16) is optionally designed as a heat conducting pad, the thickness of which decreases as pressure exerted by the control element (62) increases.

13. Apparatus according to claim 12 or 13, wherein the heat conducting element (16) has a first comb-like element (68) and a second comb-like element (70) which are complementary to one another and mesh with one another, wherein the first comb-like element (68) is arranged on the control element (62) and the second comb-like element (70) is arranged on the heat sink (14), wherein the first comb-like element (68) and the second comb-like element (70) push further into one another as pressure from the control element (62) increases.

14. Video endoscope (80) comprising an apparatus (10) according to any of the preceding claims, wherein the heat source (12) has an image sensor (42).

15. Use of an apparatus (10) according to any of the preceding claims for heat dissipation in a video endoscope (80).