JPH1168362A - Heat dissipating structure of heat releasing part group in apparatus cabinet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen a temperature difference between heat releasing parts which are each located in the upstream side and downstream side of a convection air current, by a method wherein heat radiators are arranged in series in a wind tunnel, and outside air replenishing means which replenish the wind tunnel with fresh and cool air are each provided near the convection air current inlets of the heat radiators. SOLUTION: A wind tunnel 4 which is square in cross section is provided to a cabinet 6 to suck in outside air through on outside air inlet 4-1 located at its one edge and exhausted outside through an outside air outlet 4-2 located its other edge. Heat radiators are arranged in series in the wind tunnel 4, the heat radiating parts 1-n of the heat radiators are set nearly as large in size as the inner size of the wind tunnel 4, and heat releasing parts 3-n are each indirectly mounted on the heat receiving surfaces of the heat receiving plates 2 of the heat radiators through the intermediary of the wall of the wind tunnel 4. Furthermore, outside air replenishing means 7-n which replenish the wind tunnel 4 with fresh and cool air are each provided near the convection air current inlets of the heat radiators. By this setup, a temperature difference among the heat releasing parts 3-n which are each located in the upstream side and downstream side of a convection air current can be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat dissipating structure for a group of mounted components in an equipment cabinet, and more particularly, to miniaturizing the heat dissipating structure of the group of mounted components, and upstream and downstream of convection which is inevitably generated when heat is collectively dissipated from the component group. The present invention relates to a heat radiating structure of a heat generating component group in an equipment cabinet that can reduce a temperature difference between the components.

[0002]

[Prior art]

Conventional example (1) A conventional structure of collective heat radiation of a group of heat-generating components in an equipment cabinet generally includes a heat-generating component group 13-n as shown in FIG.
In many cases, it is difficult to arrange a wind tunnel, and the gap space between the mounting board planes 11-1 and 11-2 is used as a convection flow path as it is, that is, this gap space is used. In many cases, it is used as a heat radiation space or wind tunnel replacement. Further, it is customary that a heat radiation fin group 17-n is mounted on each of the heat generating component groups 13-n and is deployed and arranged in a heat radiation space instead of a wind tunnel.

Conventional example (2)... Another example of the collective heat radiation of the heat generating component group 13-n in the conventional equipment cabinet is as shown in FIG. The cooling fan 19 and the wind tunnels 21-1 and 21-2 are mounted on the aluminum heat sink 18.
In some cases, forced convection heat radiation is carried out by connecting the two.

[0004]

In the case of the conventional example (1), as shown in FIG. 7, each of the fins of the heat radiation fin group 17-n is included in the total amount of the convection 15 sent or sucked into the equipment cabinet. A major problem is that the ratio of the amount of air that enters the gap and actually contributes to heat dissipation is small, and the cooling efficiency is extremely poor. This is a phenomenon that a large amount of air flows into a portion of the cabinet where the fluid resistance is small, and flows into the fin gaps of the radiating fins 17-n having a large fluid resistance, so that the amount of air passing through is reduced. It was due to. In addition, the convection dispersed in the cabinet in this manner has a large interference between the dispersed flows, thereby reducing the convection utilization efficiency. For this reason, an unnecessarily large fan is used as a convection-generating fan, which has caused the equipment to be large. Further, in the case of the conventional example (2), the convection downstream heat radiating component group 13-n in FIG. 8 is radiated by the air heated on the upstream side. Is introduced on the downstream side, so that the cooling efficiency on the downstream side is significantly reduced as compared with the upstream side, and the temperature of the heat-generating components is inevitably higher on the downstream side. . Further, in the case of the conventional example (2), the aluminum heat sink 18 is large, so that the device becomes large and the weight increases, which is also a big problem.

[0005]

FIG. 1 and FIG. 2 show a basic structure of a heat radiating structure of a heat generating component group in an equipment cabinet according to the present invention as means for solving the problem. Cabinet 6
A heat radiation structure for collectively absorbing the amount of heat generated by the heat-generating component group 3-n mounted therein and transporting and discarding it in the atmosphere outside the cabinet. The first component is a wind tunnel 4 having a rectangular cross section, which is a convection flow path, which is sucked in from the air outlet 1 and discharged from the outside air outlet 4-2 at the other end. A plurality of small powerful radiators are connected in series to the wind tunnel 4. Each of the radiators or the radiator groups 1-n is shaped and sized to substantially fill the inside of the wind tunnel, and each of the heat receiving surfaces of the group of the heat receiving plates 2-n. Describes an arrangement in which the heat-generating component 3-n can be mounted indirectly via a wind tunnel wall or the heat-radiating component can be mounted directly. The natural convection or forced convection 8 flowing through the wind tunnel 4 The fresh air means is a third component, and outside air replenishing means 7 for replenishing fresh cold air into the wind tunnel is provided near the convection inlet of each of the plurality of radiators arranged in series in the wind tunnel. −n is provided for each of them, and this is the fourth component, and is characterized by including all of these four components.

FIG. 1 is a schematic longitudinal sectional view of the basic structure, and FIG.
Is a schematic partial cross-sectional view near the wind tunnel portion. In FIG. 1, the auxiliary wind tunnels 5-1 and 5-2 cannot be shown, and
It is shown turned around. Auxiliary wind tunnel 5 in wind tunnel 4
Correct relative positions of 1, 5-2 are as illustrated in FIG. 2, and the correct configuration is such that the heat generating component group 3-n is exposed in the cabinet and mounted on the heat receiving plate 2-n.

[0007]

The above four components can be summarized as follows. (1) In the wind tunnel 4, a plurality of small powerful radiators or a heat radiating portion 1-n thereof are arranged in a size and a shape substantially filling the wind tunnel, and the plurality of radiators are arranged in series in the wind tunnel. It is arranged. (2) Heatsink group 3
-N is provided so that it can be directly mounted on the heat receiving plate 2-n of the radiator as much as possible. (3) Convection is either natural convection or forced convection. (4) The convection flowing into each radiator is supplemented with fresh cold air for each radiator. The operation of each component will be described below.

(1) A small and powerful radiator makes the wind tunnel smaller. In addition, the series arrangement of radiators also makes the wind tunnel smaller,
And minimize the number of wind tunnels. Since the radiator or the radiator 1-n has a size that fills the wind tunnel 4, the convection does not disperse, and the entire flow exchanges heat without waste, thereby improving the heat radiation efficiency. When a stereo radiator having heat receiving plates 2-n on both sides is adopted as the radiator, the wind tunnel 4
, The three-dimensional mounting (three-dimensional mounting) of the in-device heat generating component 3-n becomes possible, and the in-device heat generating component 3-n is efficiently mounted. The three-dimensional mounting mentioned here does not simply mean the double-sided mounting of the radiator. A plurality of heat generating component groups 3-n are arranged in series on both sides of the wind tunnel, and the wind tunnel can be arranged in any of horizontal and vertical directions. Such three-dimensional mounting of the heat generating component group 3-n not only increases the degree of freedom in mounting design, but also greatly contributes to downsizing of the equipment cabinet.

(2) When the heat radiator is installed in combination with the wind tunnel 4, the heat radiator exposes the heat receiving plate 2-n in the cabinet 6 and arranges the heat radiator as much as possible. Because it has a structure that can be mounted directly on 2-n,
As a result, the heat resistance is reduced as a whole, and the heat dissipation performance is greatly improved, in combination with the decrease in the heat resistance and the improvement in the heat dissipation efficiency according to the item (1).

(3) Either natural convection or forced convection 8-1 can be selected as convection. As one of the effects of the item (1), the configuration is such that the convection 8-1 after heat absorption does not dissipate in the cabinet, and the interior of the wind tunnel 4 and the interior of the cabinet 6 can be completely airtightly shut off. The cabinet 6 has a completely sealed structure, and forced convection 8
Even if it is -1, the inside of the cabinet 6 can be kept clean and the reliability of the mounted components can be improved. In the case of conventional forced convection means using an axial fan or the like, airtightness is poor,
In many cases, the inside of the cabinet 6 is contaminated by absorbing an externally contaminated atmosphere or taking in dust in the cabinet 6.
Further, when the chimney effect of the wind tunnel 4 is used as the natural convection generating means instead of the fan, it is possible to effectively perform the natural convection heat radiation inside the closed cabinet of the equipment, which has been extremely difficult in the past.

(4) The wind tunnel 4 is provided with means 7-n for replenishing fresh cool air to each radiator arranged in series, so that the downstream radiator is discharged from the upstream radiator. All radiators can effectively radiate heat despite being less affected by high-temperature convection and arranged in series. Further, the outside air replenishing means 7-n is characterized in that the convection supplied to the radiator increases the flow rate of the convection 8 toward the downstream radiator, thereby increasing the flow velocity. This has the effect of preventing the temperature of the vessel from rising.

The overall operation of the four components of the heat dissipation structure of the heat generating component group in the equipment cabinet according to the present invention is as follows. In the conventional heat dissipation structure, the flow of the cooling convection in the cabinet 6 is a dispersed flow, the interference between the dispersed flows is large, and the effective use of the flow is insufficient. In the structure of the present invention, the flow is concentrated and the heat dissipation structure is improved so that the heat can be efficiently utilized.At the same time, the mutual heat interference between the component groups is reduced, and the series mounting and the three-dimensional mounting can be performed. It increases the mounting density and contributes to the reduction in size and weight of the entire device.

[0013]

【Example】

[First Embodiment] FIG. 3 shows an example of a first embodiment of a heat radiation structure of a heat generating component group in a cabinet according to the present invention. In the present embodiment, a wind tunnel 4 having a square cross-sectional shape,
Is disposed inscribed in the wall of the cabinet 6, three sides are exposed in the cabinet 6, and the other side is disposed in common with a part of one side of the cabinet. The radiator applied to the second component is a stereo radiator in which a radiating pin group or a fin group is sandwiched between heat receiving plates 2-n on both sides, and the two heat receiving plates are provided. 2-n is disposed in the wind tunnel 4 with the heat receiving surface exposed in the cabinet, and the heat radiating component group 3-n mounted on the group of heat receiving plates 2-n is connected in series to the outer surfaces on both sides of the wind tunnel. The outside air replenishing means 7-n in the fourth component is provided on a part of one side of the cabinet 6 which is shared with one side of the wind tunnel, and is provided with a low-temperature fresh outside air. The feature is that it is possible to directly incorporate To have. Numeral 9 in the figure denotes a spacer for filling the radiating portion 1-n in the convection to improve the radiating efficiency. 5-1 is an auxiliary wind tunnel for forcibly supplying outside air to all the outside air replenishing means 7-n. The figure is shown in a cross-sectional view in a state where the wind tunnel 4 is held vertically, so that only one radiating portion 1-n, a large number of heat receiving plates 2-n, heat generating component groups 3-n, etc. Although only two are shown in each case, the state where many of them are arranged in series is the same as that illustrated in FIG.

FIG. 3 shows that a heat radiator, a heat generating component group 3-n, and the like are arranged and mounted in series and three-dimensionally inside and outside the wind tunnel 4, and the heat radiating structure of the heat generating component group in the equipment cabinet according to the present invention. Clearly reduces the component mounting area and volume occupied in the cabinet. In particular, the fact that one side wall of the wind tunnel 4 and a part of one side wall of the cabinet are shared reduces the occurrence of dead space due to the wind tunnel 4, effectively utilizing the space inside the cabinet, and providing fresh cold air outside the cabinet. This has the effect of facilitating incorporation. In this embodiment, since the cool air outside the cabinet introduced to the convection downstream radiator is efficiently introduced, the auxiliary wind tunnel 5-1 may be omitted.

[Second Embodiment] FIG. 4 shows an example of a second embodiment of a heat radiation structure of a heat generating component group in a cabinet according to the present invention. In the present embodiment, the first component wind tunnel 4 having a rectangular cross-sectional shape is disposed outside the wall of the cabinet 6 so as to circumscribe the wall, and the three side faces are exposed outside the cabinet 6. The other side is shared with a part of one side of the cabinet 6, and the radiator 1-n of the radiator applied to the second component is composed of a radiating pin group or a radiating fin group. Is a heat radiating portion 1-n that is arranged and arranged on one surface of one heat receiving plate 2-n, and the heat receiving plate 2-n is configured such that one side of the wind tunnel 4 is part of one side of the cabinet. In the common part, the heating component 3-n can be mounted indirectly through the cabinet wall, or the heating component 3-n can be mounted directly. The arrangement structure is arranged, and the outside air is supplemented in the fourth component. Stage 7-n is not characterized by wind tunnel 4 are provided on the three sides are provided brought exposed to the outside of the cabinet 6

In this embodiment, since the space in the cabinet 6 is not occupied by the wind tunnel 4, there is an advantage that the space in the cabinet 6 can be widely used for other purposes. The number of mountable heat-generating component groups 3-n is reduced by half. However, the location of the outside air replenishing means 7-n is three times as large as that of the first embodiment, and a large amount of fresh cold air outside the cabinet is introduced, so that the auxiliary wind tunnel 5-1 can be omitted. Although the auxiliary wind tunnel 5-1 is omitted in FIG. 4, if necessary, the auxiliary wind tunnel 5-1 is also provided to introduce forced convection into the outside air replenishing means 7-n to further improve the cooling effect. May be.

[Third Embodiment] The inside of the wind tunnel 4 and / or the cabinet 6 which is the fourth component illustrated in each embodiment diagram is illustrated.
Although there are various means as the outside air replenishing means 7-n provided on the wall of this embodiment, in the present embodiment, the external air replenishing means 7-n is provided near the position immediately before the location of each downstream radiator provided on the wind tunnel wall and / or the cabinet wall. And a louver group or a through-hole group having a predetermined structure. These outside air replenishing means 7-n have a simple structure and are easy to form, and the outside air of the wind tunnel is easily circulated by the negative pressure generated by the flow velocity of the forced convection flowing through the wind tunnel 4, so that a plurality of downstream heat radiators are provided. Supply fresh air to the vessel. As a result, the temperature rise, which is a phenomenon in which a plurality of radiators arranged in series in the wind tunnel 4 rise in temperature toward downstream of convection, is reduced.

[Fourth Embodiment] The fourth embodiment is a means for greatly enhancing the external air replenishing ability of the external air replenishing means 7-n provided in the wind tunnel 4 and / or on the wall of the cabinet 6 by forced convection. An example is shown in FIGS. 1 and 3. The illustrated auxiliary wind tunnels 5-1 and 5-2 are provided in parallel with the wind tunnel 4, and each of the outside air replenishing means 7-
A common convection introduction flow path and a common pressure chamber are formed for each louver group or through-hole group having a predetermined structure of n. One end is closed and sealed near the downstream side of the most downstream radiator,
The other end is opened in the forced convection generated by the forced convection fan 8-2 in the wind tunnel 4. With such a configuration, the auxiliary wind tunnels 5-1 and 5-2 become pressurized chambers so that fresh forced convection can be uniformly fed into the wind tunnel 4 from all louver groups and through hole groups. Become. The fresh forced convection merges with the main forced convection flowing in the wind tunnel 4 to reduce the temperature rise of the forced convection every time the radiator passes.
Since the combined forced convection is gradually increased in speed as it reaches the radiator on the downstream side, the heat exchange efficiency increases as it reaches the radiator on the downstream side. This reliably prevents the temperature rise of each downstream heat-generating component group 3-n despite the slight rise in temperature of the convection wind.

Fifth Embodiment This embodiment is an application example in which the heat radiation structure according to the present invention is implemented by natural convection. 5 and 6 are schematic sectional views, FIG. 5 is a schematic longitudinal sectional view, and FIG. 6 is a schematic transverse sectional view thereof. In FIG. 5, since the auxiliary wind tunnels 5-1 and 5-2 and the outside air replenishing means (louvers) 7-n cannot be shown in the vertical sectional view, the mounting positions are turned 90 degrees. That is, the auxiliary wind tunnels 5-1 and 5-2 and the outside air replenishing means (louvers) 7-n with respect to the wind tunnel 4 are fixed at the positions illustrated in FIG. In this embodiment, a first component, an intake port 4-1 for the outside air of the cabinet of the wind tunnel 4 is provided to penetrate the bottom floor 6-1 of the cabinet, and an exhaust port 4-2 thereof is provided at the top of the cabinet. The convection flowing through the wind tunnel 4 having a rectangular cross-sectional shape, which is provided so as to penetrate the ceiling 6-2, is a natural body flow. The third component, the convection generating means, is characterized by a chimney effect generated when the wind tunnel 4 is held vertically.

The radiator is arranged such that the group of heat receiving plates 2-n mounted on the heat receiving surface exposes the heat generating component group 3-n in the cabinet 6. Radiator 1 of radiator
Since a plurality of n are arranged in series in the wind tunnel 4, it is necessary to allow natural convection to flow through the wind tunnel 4 effectively. Coarse and small pressure loss is applied. The outside air replenishing means (louvers) 7-n are provided near the convection suction portions of the heat radiation portions 1-n. The auxiliary wind tunnels 5-1 and 5-2 inhale fresh low-temperature outside air from the inlets 4-3 and 4-4 by a chimney effect and uniformly supply the outside air to all outside air replenishing means (louvers) 7-n. In the wind tunnel 4, the outside air sucked from the suction port 4-1 flows through while absorbing the heat quantity of each heat radiating portion 1-n by a strong chimney effect. n, fresh outside air is replenished for each heat radiating section 1-n, the convection flow rate increases, the flow velocity also increases, the heat exchange efficiency increases toward the downstream side, and each heat generating component 3-n is relatively distributed upstream and downstream. Cooled uniformly.

In this embodiment, since the convective exhaust gas after the heat exchange does not dissipate in the cabinet 6 at all, the cabinet 6 can be completely sealed, which is a great effect. In the conventional direct cooling by natural convection of the heat generating component group 3-n in the closed cabinet 6, the convective exhaust gas after the heat exchange is dissipated in the closed cabinet 6, and the air temperature in the cabinet 6 is increased. And the natural body cooling of the heat-generating component group 3-n in the closed cabinet 6 is almost impossible. Cooling of the heat generating component group 3-n in the closed cabinet 6 of the current equipment is performed by exchanging heat inside and outside the cabinet 6 with a heat exchanger provided with forced convection generating means inside and outside the closed cabinet 6 to cool the air inside the cabinet. Then, it is common to apply a very inefficient cooling means for indirectly cooling the heat generating component group 3-n.

[0022]

According to the present invention, the small and powerful radiator is arranged in series in the small wind tunnel, so that the mounting area of the heat generating components in the equipment cabinet is reduced, and the outside air replenishing means and the auxiliary wind tunnel provided in the wind tunnel are provided. Due to the action, the temperature difference between the heat-generating components between the upstream and downstream of the convection is greatly reduced, the three-dimensional mounting of the heat-generating components is facilitated, and the equipment cabinet is downsized. In addition, since the cooling convection does not dissipate in the cabinet, the cabinet can be hermetically sealed, and in particular, natural convection cooling of the heat-generating components in the closed cabinet has also become possible.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a basic structure of a heat radiation structure of a heat generating component group in an equipment cabinet of the present invention.

FIG. 2 is a schematic cross-sectional view of a wind tunnel portion showing a basic structure of a heat radiation structure of a heat generating component group in an equipment cabinet according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a first embodiment of a heat radiation structure of a heat generating component group in an equipment cabinet according to the present invention.

FIG. 4 is a schematic cross-sectional view showing a second embodiment of the heat radiation structure of the heat generating component group in the equipment cabinet of the present invention.

FIG. 5 is a schematic longitudinal sectional view showing a fifth embodiment of the heat radiation structure of the heat generating component group in the equipment cabinet of the present invention.

FIG. 6 is a schematic cross-sectional view showing a fifth embodiment of the heat radiation structure of the heat generating component group in the equipment cabinet of the present invention.

FIG. 7 is an explanatory view of an example of a conventional structure of a heat radiation structure of a heat generating component group in an equipment cabinet.

FIG. 8 is an explanatory view of another example of the conventional structure of the heat radiation structure of the heat generating component group in the equipment cabinet.

[Explanation of symbols]

 1-n radiator radiator 2-n radiator heat receiving plate 3-n heat-generating component 4 wind tunnel 4-1 outside air inlet 4-2 outside air outlet 4-3 auxiliary wind tunnel inlet 4-4 auxiliary wind tunnel inlet 5-1 Auxiliary wind tunnel 5-2 Auxiliary wind tunnel 6 Cabinet 6-1 Cabinet bottom floor 6-2 Cabinet top ceiling 7-n External air replenishment means (louver) 8-1 Forced convection 8-2 Forced convection generation means (fan) 9 Spacer 11-1 Printed circuit board 11-2 Printed circuit board 13-n Heat generating component 14-1 Support plate 14-2 Support plate 15 Forced convection 17-n Radiation fin 18 Large heat sink 19 Cooling fan 20 Cabinet 21-1 Wind tunnel 21-2 Wind tunnel

Claims (6)

[Claims] 1. A heat radiation structure for collectively absorbing heat generated by a heat generating component group mounted in an equipment cabinet and transferring and disposing the heat to an atmosphere outside the cabinet. The first component is a wind tunnel having a rectangular cross section that is a convection flow path discharged from the other end, and a plurality of small powerful radiators are arranged in series in the wind tunnel.
Each of these radiators or their radiating units should have a shape and size that almost completely fills the inside of the wind tunnel, and each heat receiving surface of those heat receiving units should be indirectly mounted with heat-generating components via the wind tunnel wall. Or the second component can be installed directly on each heat-receiving surface of the group of heat-receiving units. The means for generating natural convection or forced convection is the third component, and outside air is supplied to the wind tunnel to replenish fresh cold air into the wind tunnel from around the convection inlet of each downstream radiator arranged in series. A heat dissipating structure for a heat-generating component group in an equipment cabinet, wherein a means is provided for each of the four components, and the fourth component is used as the fourth component. 2. The first component is a rectangular wind tunnel inscribed in the cabinet wall, three sides are exposed in the cabinet, and the other side is one side of the cabinet. A plurality of radiators applied to the second component are arranged in common with a part, and each of the radiators is a stereo in which a radiating pin group or a fin group is sandwiched between two heat receiving plates on both sides. These heat receiving plates are arranged in the wind tunnel with their heat receiving surfaces exposed in the cabinet, and the heat radiating devices mounted on the heat receiving plates are arranged in series on both outer surfaces on both sides of the wind tunnel. And the outside air replenishment means in the fourth component is provided for each downstream radiator in a portion of one side of the cabinet shared with one side of the wind tunnel. The device carrier according to claim 1, wherein Heat dissipating structure of heat generating components in vignette. 3. The first component is a rectangular wind tunnel disposed circumscribing the outside of the cabinet wall, three sides exposed to the outside of the cabinet, and the other side is defined by one side of the cabinet. The heat dissipating parts of multiple radiators applied to the second component are arranged in common with a part, and the heat dissipating pins or heat dissipating fins are arranged on one side of one heat receiving plate The heat receiving surface of each of the heat receiving plates is indirectly connected to a portion of one side of the wind tunnel and one side of the cabinet through a cabinet wall. Either a heat-generating component can be mounted, or a heat-radiating component can be mounted directly, which is an arrangement structure arranged so as to be either, and the outside air replenishment means in the fourth component is: The wind tunnel was exposed outside the cabinet The heat dissipating structure of a group of heat generating components in an equipment cabinet according to claim 1, wherein the heat dissipating parts are provided on the three side surfaces for each downstream radiator. 4. The outside air replenishment means of each downstream radiator of the plurality of radiators arranged in series in the wind tunnel of the fourth component, the arrangement of each downstream radiator on the wind tunnel wall and / or the cabinet wall. 2. A louver group or a through-hole group having a predetermined structure provided immediately before the installation position.
Heat dissipating structure of the heat generating components in the cabinet described in the above. 5. The outside air replenishing means of each downstream radiator of the plurality of radiators arranged in series in the wind tunnel of the fourth component has a predetermined structure provided on a wind tunnel wall and / or a cabinet wall. 2. The heat radiating structure for a heat generating component group in an equipment cabinet according to claim 1, wherein the louver group or the through-hole group is provided with means for sending forced convection. 6. A first component of the wind tunnel, in which a suction port for the outside air of the cabinet is provided through the bottom floor of the cabinet, and a discharge port thereof is provided through the top ceiling of the cabinet. There is a convection flowing through the wind tunnel with a rectangular cross section characterized by natural convection, and the third component, convection generating means, is a chimney effect generated by the wind tunnel being held vertically. The heat radiating structure of a heat generating component group in an equipment cabinet according to claim 1, wherein: