Heat Storage Means, More Especially a Latent Heat Storage Means

The invention relates to a heat storage means, more especially a latent heat storage means for motor vehicle heating systems using waste engine heat, comprising an inner housing enclosing a storage core, an outer housing enclosing the inner housing with a clearance therebetween, thermal insulation between the inner and the outer housings, a supply duct and a drain duct for a fluid to transport heat, such ducts extending through the thermal insulation to the inner housing.

In order to prevent losses of the stored heat to the greatest possible extent it is necessary to have a highly efficient insulation between the inner and the outer housings, there being more especially the requirement for a comparatively small volume of the insulation to ensure that the overall volume of the heat storage means may be kept small, as is more especially required for installation in motor vehicles, because only a small amount of space is available for additional equipment. In order not to additionally increase the weight of the vehicle, the weight of such a heat storage means should also be kept as low as possible.

An insulation which is more especially suitable for meeting all these needs is a vacuum gap between the inner housing and the outer housing. In this respect it is necessary to anchor the inner housing within the outer one, which for its part should have a minimum weight and cause only minimum heat losses.

Accordingly, the object of the invention is to design a heat storage means for the initially mentioned type such that the inner housing is located in the outer housing in the simplest possible and reliable manner, such anchoring means furthermore fulfilling the requirements of the least possible weight, the lowest possible thermal losses and allowance for thermal expansion taking place with fluctuations in temperature.

In order to achieve this object in the invention the inner housing is supported on two end faces facing away from each other by means of respective a group of ribs with a small cross section on the outer housing and in that between end wall of the inner housing and the outer housing at least one spring is so mounted that it tends to change the distance between opposite end walls of the inner and of the outer housing.

The anchoring in place of the inner housing within the outer one by suspension means offers the advantage the essentially only tensile forces have to be transmitted so that small cross sections are possible which on the one hand mean that the necessary weight on the one hand the thermal losses occurring on the other hand may be kept low. Each group of ribs comprises at least two and preferably about three or four ribs in order to oppose lateral displacement of the housing.

In accordance with an advantageous development of the invention the supply and drain ducts emerge at least in the proximity of the end wall of the inner housing with which the spring is in engagement. Owing to this a relative motion of the inner and of the outer housing adjacent to the pipe ducts is reduced and the tubes are relieved of mechanical loads.

In accordance with a particularly expedient for the invention the ribs of at least one group are united as a single suspension element so that assembly becomes particularly simple.

A further convenient development is such that at least one suspending means is connected in a torsionally stiff manner with the inner housing, there preferably being two spaced attachment points on one end wall of the inner housing in a symmetrical arrangement for the suspending means. In this respect a further convenient development then becomes possible inasfar as the suspending means has two connection points associated with the attachment points on the inner housing, and from such connection points there extend two ribs placed respectively V-like manner to an outer frame, which enclose the other connection point on their bisector between them so that the two pairs of ribs arranged in the form of a letter V intersect with the formation of a diamond-like inner frame.

The spring may be mounted either between mutually opposite end walls of the inner housing and of the outer one or between the end wall of the inner housing and the suspending element, associated with this end wall. Preferably, the spring engages the center of the end surface of the inner housing.

As a further convenient development of the invention the suspending element may be provided on the end wall, cooperating with the spring, of the inner housing with a central connection point, at which the ribs are united.

Preferably there is a guide sleeve on the end surface acted upon by the spring, for the spring and the central connection point of the suspending means is in the form of a ring fitting around this guide sleeve.

A further convenient development of the invention is such that the effective length of the spring is able to be adjusted.

Preferably the suspending elements are in the form of stampings.

On the basis the following description an account in more detail will now be given of the invention with reference to the working example shown in the drawing

FIG. 1 shows an axial section taken through a heat storage means designed in accordance with the invention with a cylindrical shape of housing.

FIG. 2 shows a modification of the left hand end of the heat storage means of FIG. 1.

FIG. 3 is a view of the suspension element arranged on the left in FIG. 1.

FIG. 4 is a view of the suspension element arranged on the right in FIG. 1.

The heat storage means shown consists of an inner housing 10 and an outer housing 12, between which a vacuum chamber 14 is formed. A supply duct 16 and a drain duct 18 are connected in the upper part of an end wall 20 of the inner housing 10 and extend vertically through the vacuum chamber 14 downwards out of the outer housing 12.

The outer housing 12 consists of a cylindrical casing 24 reinforced by grooves 22 and two end walls 26 and 28 mounted in this casing 24. Adjacent to the left hand end wall 26 (see FIG. 1) there is a suspension element 30 on the inner side of the outer housing 12, it being attached for instance by welding. Adjacent to the right hand wall 28 there is a further suspension element 32 which is attached to the inner surface of the casing 24.

In the center of the left hand end wall 20 of the inner housing 10 there is mounted a guide sleeve 34 for a helical compression spring 26, same being held so as to be coaxial to the housings 10 and 12 between the inner housing 10 and outer one 12. The end wall 26, opposite to the end wall 20, of the outer housing also has a guide sleeve 38 for the compression spring 36, which is provided with an axially adjustable inert 40 for changing the effective length of the compression spring 36.

The suspension element 30 (see FIG. 3) possesses a inner annular frame 42, from which there extend four radial ribs 44, each offset from the next one by 90.degree., which at there ends are provided with attachment flanges 46 for connection with the casing 24. The ribs 44 are in this respect so bent in relation to the plane of the inner frame 42 that they make an acute angle with the axis of the inner frame and are constantly kept stressed by the compression spring 36. In order to attach the inner frame 42 on the end wall 20 it is possible to employ a thrust plate 48, which also fits in an annular manner around the guide sleeve 34 and which is connected with the end wall 20 of the inner housing 10.

At the other end wall 50 of the inner housing 10 for connection of the suspension element 32 there is a bracket 52, on which in the vertical plane of symmetry of the inner housing 10 with the same spacing from the axis of this housing 10 two connection pins 54 and 56 are arranged with which on an inner frame 58 of the suspending element 32 two holes 60 and 62 are associated. Ribs 68 and 70 and, respectively, 72 and 74 extend in pairs from the sections 64 and 66, respectively, surrounding these holes 60 and 62, of the inner frame. The ribs 68 and 70 and, respectively, 72 and 74 of each pair of ribs are in each case arranged in the form of a letter V so that they unite in the section 64, and, respectively, 64 and the hole 62 or 60, respectively, arranged in the other respective section 66 and 64 is on its bisector and is enclosed by them. The two pairs of ribs 68 and 70 and, respectively 72 and 74 thus intersect with each other so that the inner frame 58 is diamond-shaped. The outer ends of the ribs 68 through 74 are connected with each other by an annular outer frame 76 with each other which has a bent part 78 able to be connected with the inner surface of the casing 24.

In this arrangement the suspending element 30 functions primarily to axially locate the inner housing 10 in relation to the outer housing 12, whereas the suspending element 32 serves primarily to maintain the set radial distance between the two housings 10 and 12 and at the same time prevents twisting of the two housings 10 and 12 in relation to each other.

In lieu of placing the compression spring 36 directly between the inner housing 10 and the outer one 12, it is possible, as shown in FIG. 2, for instance to place the spring 36 directly on the inner housing 10 and for it to be indirectly connected with the outer housing 12 by causing one end of the compression spring 36 to bear on the end wall 20 of the inner housing 10 while its other end bears on the suspending element, the compression spring 36 having a guide pin 80 extending through it which is connected with the end wall 20 and on the pin 80 there is an adjustable nut 82 on the side of the suspending element 30 remote from the inner housing 10.